From b78ad5cd6feea006986869506f33aab84c37398a Mon Sep 17 00:00:00 2001
From: Florian Verdonck <florian.verdonck@outlook.com>
Date: Wed, 12 Oct 2022 15:00:32 +0200
Subject: [PATCH 1/8] Add SynType.Or. (#14058)

* Add SynType.Or for generic constrains in the form (^A or ^B):...
---
 src/Compiler/Checking/CheckExpressions.fs     |   8 +-
 src/Compiler/FSComp.txt                       |   1 +
 src/Compiler/Service/ServiceParseTreeWalk.fs  |   3 +-
 src/Compiler/Service/ServiceParsedInputOps.fs |  14 +-
 src/Compiler/SyntaxTree/SyntaxTree.fs         |   9 +-
 src/Compiler/SyntaxTree/SyntaxTree.fsi        |   7 +-
 src/Compiler/SyntaxTree/SyntaxTreeOps.fs      |   9 +
 src/Compiler/SyntaxTree/SyntaxTreeOps.fsi     |   2 +
 src/Compiler/SyntaxTree/SyntaxTrivia.fs       |   3 +
 src/Compiler/SyntaxTree/SyntaxTrivia.fsi      |   8 +
 src/Compiler/pars.fsy                         |  25 ++-
 src/Compiler/xlf/FSComp.txt.cs.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.de.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.es.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.fr.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.it.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.ja.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.ko.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.pl.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.pt-BR.xlf         |   5 +
 src/Compiler/xlf/FSComp.txt.ru.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.tr.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.zh-Hans.xlf       |   5 +
 src/Compiler/xlf/FSComp.txt.zh-Hant.xlf       |   5 +
 ...erService.SurfaceArea.netstandard.expected |  30 +++-
 tests/service/SyntaxTreeTests/SynTypeTests.fs | 156 ++++++++++++++++++
 26 files changed, 311 insertions(+), 29 deletions(-)

diff --git a/src/Compiler/Checking/CheckExpressions.fs b/src/Compiler/Checking/CheckExpressions.fs
index 9e21c434270..a83ef7d669b 100644
--- a/src/Compiler/Checking/CheckExpressions.fs
+++ b/src/Compiler/Checking/CheckExpressions.fs
@@ -3953,7 +3953,7 @@ let rec TcTyparConstraint ridx (cenv: cenv) newOk checkConstraints occ (env: TcE
     | SynTypeConstraint.WhereTyparIsDelegate(tp, synTys, m) ->
         TcConstraintWhereTyparIsDelegate cenv env newOk checkConstraints occ tpenv tp synTys m
 
-    | SynTypeConstraint.WhereTyparSupportsMember(synSupportTys, synMemberSig, m) ->
+    | SynTypeConstraint.WhereTyparSupportsMember(TypesForTypar synSupportTys, synMemberSig, m) ->
         TcConstraintWhereTyparSupportsMember cenv env newOk tpenv synSupportTys synMemberSig m
 
     | SynTypeConstraint.WhereSelfConstrained(ty, m) ->
@@ -4361,6 +4361,10 @@ and TcTypeOrMeasure kindOpt (cenv: cenv) newOk checkConstraints occ (iwsam: Warn
     | SynType.Paren(innerType, _)
     | SynType.SignatureParameter(usedType = innerType) ->
         TcTypeOrMeasure kindOpt cenv newOk checkConstraints occ iwsam env tpenv innerType
+    
+    | SynType.Or(range = m) ->
+        // The inner types are expected to be collected by (|TypesForTypar|) at this point.
+        error(Error((FSComp.SR.tcSynTypeOrInvalidInDeclaration()), m))
 
 and CheckIWSAM (cenv: cenv) (env: TcEnv) checkConstraints iwsam m tcref =
     let g = cenv.g
@@ -5651,7 +5655,7 @@ and TcExprUndelayed (cenv: cenv) (overallTy: OverallTy) env tpenv (synExpr: SynE
         TcNonControlFlowExpr env <| fun env ->
         TcExprNamedIndexPropertySet cenv overallTy env tpenv (synLongId, synExpr1, synExpr2, mStmt)
 
-    | SynExpr.TraitCall (tps, synMemberSig, arg, m) ->
+    | SynExpr.TraitCall (TypesForTypar tps, synMemberSig, arg, m) ->
         TcNonControlFlowExpr env <| fun env ->
         TcExprTraitCall cenv overallTy env tpenv (tps, synMemberSig, arg, m)
 
diff --git a/src/Compiler/FSComp.txt b/src/Compiler/FSComp.txt
index 80c356d31db..2e3267b01a7 100644
--- a/src/Compiler/FSComp.txt
+++ b/src/Compiler/FSComp.txt
@@ -1656,3 +1656,4 @@ reprStateMachineInvalidForm,"The state machine has an unexpected form"
 3546,parsExpectingPatternInTuple,"Expecting pattern"
 3547,parsExpectedPatternAfterToken,"Expected a pattern after this point"
 3548,matchNotAllowedForUnionCaseWithNoData,"Pattern discard is not allowed for union case that takes no data."
+3549,tcSynTypeOrInvalidInDeclaration,"SynType.Or is not permitted in this declaration"
\ No newline at end of file
diff --git a/src/Compiler/Service/ServiceParseTreeWalk.fs b/src/Compiler/Service/ServiceParseTreeWalk.fs
index f3443fd95ff..274d2741365 100755
--- a/src/Compiler/Service/ServiceParseTreeWalk.fs
+++ b/src/Compiler/Service/ServiceParseTreeWalk.fs
@@ -821,7 +821,8 @@ module SyntaxTraversal =
                 | SynType.WithGlobalConstraints (ty, _, _)
                 | SynType.Array (_, ty, _) -> traverseSynType path ty
                 | SynType.StaticConstantNamed (ty1, ty2, _)
-                | SynType.MeasureDivide (ty1, ty2, _) -> [ ty1; ty2 ] |> List.tryPick (traverseSynType path)
+                | SynType.MeasureDivide (ty1, ty2, _)
+                | SynType.Or (ty1, ty2, _, _) -> [ ty1; ty2 ] |> List.tryPick (traverseSynType path)
                 | SynType.Tuple (path = segments) -> getTypeFromTuplePath segments |> List.tryPick (traverseSynType path)
                 | SynType.StaticConstantExpr (expr, _) -> traverseSynExpr [] expr
                 | SynType.Paren (innerType = t)
diff --git a/src/Compiler/Service/ServiceParsedInputOps.fs b/src/Compiler/Service/ServiceParsedInputOps.fs
index ef194965b34..3ff647478a8 100644
--- a/src/Compiler/Service/ServiceParsedInputOps.fs
+++ b/src/Compiler/Service/ServiceParsedInputOps.fs
@@ -607,7 +607,7 @@ module ParsedInput =
             | SynTypeConstraint.WhereTyparIsComparable (t, _) -> walkTypar t
             | SynTypeConstraint.WhereTyparIsEquatable (t, _) -> walkTypar t
             | SynTypeConstraint.WhereTyparSubtypeOfType (t, ty, _) -> walkTypar t |> Option.orElseWith (fun () -> walkType ty)
-            | SynTypeConstraint.WhereTyparSupportsMember (ts, sign, _) ->
+            | SynTypeConstraint.WhereTyparSupportsMember (TypesForTypar ts, sign, _) ->
                 List.tryPick walkType ts |> Option.orElseWith (fun () -> walkMemberSig sign)
             | SynTypeConstraint.WhereTyparIsEnum (t, ts, _) -> walkTypar t |> Option.orElseWith (fun () -> List.tryPick walkType ts)
             | SynTypeConstraint.WhereTyparIsDelegate (t, ts, _) -> walkTypar t |> Option.orElseWith (fun () -> List.tryPick walkType ts)
@@ -668,7 +668,8 @@ module ParsedInput =
             | SynType.Fun (argType = t1; returnType = t2) -> walkType t1 |> Option.orElseWith (fun () -> walkType t2)
             | SynType.WithGlobalConstraints (t, _, _) -> walkType t
             | SynType.HashConstraint (t, _) -> walkType t
-            | SynType.MeasureDivide (t1, t2, _) -> walkType t1 |> Option.orElseWith (fun () -> walkType t2)
+            | SynType.MeasureDivide (t1, t2, _)
+            | SynType.Or (t1, t2, _, _) -> walkType t1 |> Option.orElseWith (fun () -> walkType t2)
             | SynType.MeasurePower (t, _, _) -> walkType t
             | SynType.Paren (t, _)
             | SynType.SignatureParameter (usedType = t) -> walkType t
@@ -838,7 +839,7 @@ module ParsedInput =
 
             | SynExpr.DoBang (e, _) -> walkExprWithKind parentKind e
 
-            | SynExpr.TraitCall (ts, sign, e, _) ->
+            | SynExpr.TraitCall (TypesForTypar ts, sign, e, _) ->
                 List.tryPick walkType ts
                 |> Option.orElseWith (fun () -> walkMemberSig sign)
                 |> Option.orElseWith (fun () -> walkExprWithKind parentKind e)
@@ -1621,7 +1622,7 @@ module ParsedInput =
             | SynTypeConstraint.WhereTyparIsDelegate (t, ts, _) ->
                 walkTypar t
                 List.iter walkType ts
-            | SynTypeConstraint.WhereTyparSupportsMember (ts, sign, _) ->
+            | SynTypeConstraint.WhereTyparSupportsMember (TypesForTypar ts, sign, _) ->
                 List.iter walkType ts
                 walkMemberSig sign
             | SynTypeConstraint.WhereSelfConstrained (ty, _) -> walkType ty
@@ -1673,7 +1674,8 @@ module ParsedInput =
             | SynType.Paren (t, _)
             | SynType.SignatureParameter (usedType = t) -> walkType t
             | SynType.Fun (argType = t1; returnType = t2)
-            | SynType.MeasureDivide (t1, t2, _) ->
+            | SynType.MeasureDivide (t1, t2, _)
+            | SynType.Or (t1, t2, _, _) ->
                 walkType t1
                 walkType t2
             | SynType.LongIdent ident -> addLongIdentWithDots ident
@@ -1820,7 +1822,7 @@ module ParsedInput =
                     walkExpr eAndBang
 
                 walkExpr e2
-            | SynExpr.TraitCall (ts, sign, e, _) ->
+            | SynExpr.TraitCall (TypesForTypar ts, sign, e, _) ->
                 List.iter walkType ts
                 walkMemberSig sign
                 walkExpr e
diff --git a/src/Compiler/SyntaxTree/SyntaxTree.fs b/src/Compiler/SyntaxTree/SyntaxTree.fs
index 7ef394a67f0..051bb1e7af8 100644
--- a/src/Compiler/SyntaxTree/SyntaxTree.fs
+++ b/src/Compiler/SyntaxTree/SyntaxTree.fs
@@ -330,7 +330,7 @@ type SynTypeConstraint =
 
     | WhereTyparSubtypeOfType of typar: SynTypar * typeName: SynType * range: range
 
-    | WhereTyparSupportsMember of typars: SynType list * memberSig: SynMemberSig * range: range
+    | WhereTyparSupportsMember of typars: SynType * memberSig: SynMemberSig * range: range
 
     | WhereTyparIsEnum of typar: SynTypar * typeArgs: SynType list * range: range
 
@@ -441,6 +441,8 @@ type SynType =
 
     | SignatureParameter of attributes: SynAttributes * optional: bool * id: Ident option * usedType: SynType * range: range
 
+    | Or of lhsType: SynType * rhsType: SynType * range: range * trivia: SynTypeOrTrivia
+
     member x.Range =
         match x with
         | SynType.App (range = m)
@@ -459,7 +461,8 @@ type SynType =
         | SynType.MeasureDivide (range = m)
         | SynType.MeasurePower (range = m)
         | SynType.Paren (range = m)
-        | SynType.SignatureParameter (range = m) -> m
+        | SynType.SignatureParameter (range = m)
+        | SynType.Or (range = m) -> m
         | SynType.LongIdent lidwd -> lidwd.Range
 
 [<NoEquality; NoComparison; RequireQualifiedAccess>]
@@ -647,7 +650,7 @@ type SynExpr =
 
     | AddressOf of isByref: bool * expr: SynExpr * opRange: range * range: range
 
-    | TraitCall of supportTys: SynType list * traitSig: SynMemberSig * argExpr: SynExpr * range: range
+    | TraitCall of supportTys: SynType * traitSig: SynMemberSig * argExpr: SynExpr * range: range
 
     | JoinIn of lhsExpr: SynExpr * lhsRange: range * rhsExpr: SynExpr * range: range
 
diff --git a/src/Compiler/SyntaxTree/SyntaxTree.fsi b/src/Compiler/SyntaxTree/SyntaxTree.fsi
index 8d977a4c027..4ecffe92ef4 100644
--- a/src/Compiler/SyntaxTree/SyntaxTree.fsi
+++ b/src/Compiler/SyntaxTree/SyntaxTree.fsi
@@ -405,7 +405,7 @@ type SynTypeConstraint =
     | WhereTyparSubtypeOfType of typar: SynTypar * typeName: SynType * range: range
 
     /// F# syntax is ^T: (static member MemberName: ^T * int -> ^T)
-    | WhereTyparSupportsMember of typars: SynType list * memberSig: SynMemberSig * range: range
+    | WhereTyparSupportsMember of typars: SynType * memberSig: SynMemberSig * range: range
 
     /// F# syntax is 'typar: enum<'UnderlyingType>
     | WhereTyparIsEnum of typar: SynTypar * typeArgs: SynType list * range: range
@@ -518,6 +518,9 @@ type SynType =
         usedType: SynType *
         range: range
 
+    /// F# syntax: ^a or ^b, used in trait calls
+    | Or of lhsType: SynType * rhsType: SynType * range: range * trivia: SynTypeOrTrivia
+
     /// Gets the syntax range of this construct
     member Range: range
 
@@ -817,7 +820,7 @@ type SynExpr =
     | AddressOf of isByref: bool * expr: SynExpr * opRange: range * range: range
 
     /// F# syntax: ((type1 or ... or typeN): (member-dig) expr)
-    | TraitCall of supportTys: SynType list * traitSig: SynMemberSig * argExpr: SynExpr * range: range
+    | TraitCall of supportTys: SynType * traitSig: SynMemberSig * argExpr: SynExpr * range: range
 
     /// F# syntax: ... in ...
     /// Computation expressions only, based on JOIN_IN token from lex filter
diff --git a/src/Compiler/SyntaxTree/SyntaxTreeOps.fs b/src/Compiler/SyntaxTree/SyntaxTreeOps.fs
index aefc238d10e..fda76bc0e47 100644
--- a/src/Compiler/SyntaxTree/SyntaxTreeOps.fs
+++ b/src/Compiler/SyntaxTree/SyntaxTreeOps.fs
@@ -1082,3 +1082,12 @@ let (|MultiDimensionArrayType|_|) (t: SynType) =
         else
             None
     | _ -> None
+
+let (|TypesForTypar|) (t: SynType) =
+    let rec visit continuation t =
+        match t with
+        | SynType.Paren (innerT, _) -> visit continuation innerT
+        | SynType.Or (lhsT, rhsT, _, _) -> visit (fun lhsTs -> [ yield! lhsTs; yield rhsT ] |> continuation) lhsT
+        | _ -> continuation [ t ]
+
+    visit id t
diff --git a/src/Compiler/SyntaxTree/SyntaxTreeOps.fsi b/src/Compiler/SyntaxTree/SyntaxTreeOps.fsi
index b78563d4bce..bb72345971e 100644
--- a/src/Compiler/SyntaxTree/SyntaxTreeOps.fsi
+++ b/src/Compiler/SyntaxTree/SyntaxTreeOps.fsi
@@ -357,3 +357,5 @@ val desugarGetSetMembers: memberDefns: SynMemberDefns -> SynMemberDefns
 val getTypeFromTuplePath: path: SynTupleTypeSegment list -> SynType list
 
 val (|MultiDimensionArrayType|_|): t: SynType -> (int * SynType * range) option
+
+val (|TypesForTypar|): t: SynType -> SynType list
diff --git a/src/Compiler/SyntaxTree/SyntaxTrivia.fs b/src/Compiler/SyntaxTree/SyntaxTrivia.fs
index fa4ebc784c8..7c15170e74f 100644
--- a/src/Compiler/SyntaxTree/SyntaxTrivia.fs
+++ b/src/Compiler/SyntaxTree/SyntaxTrivia.fs
@@ -265,3 +265,6 @@ type SynMemberGetSetTrivia =
 
 [<NoEquality; NoComparison>]
 type SynArgPatsNamePatPairsTrivia = { ParenRange: range }
+
+[<NoEquality; NoComparison>]
+type SynTypeOrTrivia = { OrKeyword: range }
diff --git a/src/Compiler/SyntaxTree/SyntaxTrivia.fsi b/src/Compiler/SyntaxTree/SyntaxTrivia.fsi
index b6f0532d73c..c52cacea7b2 100644
--- a/src/Compiler/SyntaxTree/SyntaxTrivia.fsi
+++ b/src/Compiler/SyntaxTree/SyntaxTrivia.fsi
@@ -384,3 +384,11 @@ type SynArgPatsNamePatPairsTrivia =
         /// The syntax range from the beginning of the `(` token till the end of the `)` token.
         ParenRange: range
     }
+
+/// Represents additional information for SynType.Or
+[<NoEquality; NoComparison>]
+type SynTypeOrTrivia =
+    {
+        /// The syntax range of the `or` keyword
+        OrKeyword: range
+    }
diff --git a/src/Compiler/pars.fsy b/src/Compiler/pars.fsy
index 4b5888bf2f4..1dc110accee 100644
--- a/src/Compiler/pars.fsy
+++ b/src/Compiler/pars.fsy
@@ -2226,10 +2226,12 @@ typeConstraint:
 
   | typar COLON LPAREN classMemberSpfn rparen 
      { let tp = $1
-       SynTypeConstraint.WhereTyparSupportsMember([ SynType.Var(tp, tp.Range) ], $4, lhs parseState) }
+       SynTypeConstraint.WhereTyparSupportsMember(SynType.Var(tp, tp.Range), $4, lhs parseState) }
 
   | LPAREN typeAlts rparen COLON LPAREN classMemberSpfn rparen 
-     { SynTypeConstraint.WhereTyparSupportsMember(List.rev($2), $6, lhs parseState) }
+     { let mParen = rhs2 parseState 1 3
+       let t = SynType.Paren($2, mParen)
+       SynTypeConstraint.WhereTyparSupportsMember(t, $6, lhs parseState) }
 
   | typar COLON DELEGATE typeArgsNoHpaDeprecated
      { let _ltm, _gtm, args, _commas, mWhole = $4
@@ -2254,10 +2256,12 @@ typeConstraint:
 
 typeAlts:
   | typeAlts OR appType
-     { $3 :: $1 }
+     { let mOr = rhs parseState 2
+       let m = unionRanges $1.Range $3.Range
+       SynType.Or($1, $3, m, { OrKeyword = mOr }) }
 
   | appType
-     { [$1] }	
+     { $1 }
 
 /* The core of a union type definition */
 unionTypeRepr:
@@ -4485,17 +4489,20 @@ parenExprBody:
 
 typars:
   | typar 
-      { [SynType.Var($1, rhs parseState 1)] }
+      { SynType.Var($1, rhs parseState 1) }
 
-  | LPAREN typarAlts rparen 
-      { List.rev $2 }
+  | LPAREN typarAlts rparen
+      { let m = rhs2 parseState 1 3
+        SynType.Paren($2, m) }
 
 typarAlts:
   | typarAlts OR appType
-      {$3 :: $1}
+      { let mOr = rhs parseState 2
+        let m = unionRanges $1.Range $3.Range
+        SynType.Or($1, $3, m, { OrKeyword = mOr }) }
 
   | typar
-      { [SynType.Var($1, rhs parseState 1)] }
+      { SynType.Var($1, rhs parseState 1) }
 
 braceExpr:
   | LBRACE braceExprBody rbrace 
diff --git a/src/Compiler/xlf/FSComp.txt.cs.xlf b/src/Compiler/xlf/FSComp.txt.cs.xlf
index 7cccaaa5d29..1489085bcb7 100644
--- a/src/Compiler/xlf/FSComp.txt.cs.xlf
+++ b/src/Compiler/xlf/FSComp.txt.cs.xlf
@@ -977,6 +977,11 @@
         <target state="translated">Tento výraz implicitně převede typ {0} na typ {1}. Přečtěte si téma https://aka.ms/fsharp-implicit-convs.</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcSynTypeOrInvalidInDeclaration">
+        <source>SynType.Or is not permitted in this declaration</source>
+        <target state="new">SynType.Or is not permitted in this declaration</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcTraitHasMultipleSupportTypes">
         <source>The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</source>
         <target state="new">The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.de.xlf b/src/Compiler/xlf/FSComp.txt.de.xlf
index 159319c2da5..00da1cbd6af 100644
--- a/src/Compiler/xlf/FSComp.txt.de.xlf
+++ b/src/Compiler/xlf/FSComp.txt.de.xlf
@@ -977,6 +977,11 @@
         <target state="translated">Dieser Ausdruck konvertiert den Typ "{0}" implizit in den Typ "{1}". Siehe https://aka.ms/fsharp-implicit-convs.</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcSynTypeOrInvalidInDeclaration">
+        <source>SynType.Or is not permitted in this declaration</source>
+        <target state="new">SynType.Or is not permitted in this declaration</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcTraitHasMultipleSupportTypes">
         <source>The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</source>
         <target state="new">The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.es.xlf b/src/Compiler/xlf/FSComp.txt.es.xlf
index 92090c2cfb0..f6cdcdddad2 100644
--- a/src/Compiler/xlf/FSComp.txt.es.xlf
+++ b/src/Compiler/xlf/FSComp.txt.es.xlf
@@ -977,6 +977,11 @@
         <target state="translated">Esta expresión convierte implícitamente el tipo '{0}' al tipo '{1}'. Consulte https://aka.ms/fsharp-implicit-convs.</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcSynTypeOrInvalidInDeclaration">
+        <source>SynType.Or is not permitted in this declaration</source>
+        <target state="new">SynType.Or is not permitted in this declaration</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcTraitHasMultipleSupportTypes">
         <source>The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</source>
         <target state="new">The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.fr.xlf b/src/Compiler/xlf/FSComp.txt.fr.xlf
index eef8d9e96dd..ec74d45bf45 100644
--- a/src/Compiler/xlf/FSComp.txt.fr.xlf
+++ b/src/Compiler/xlf/FSComp.txt.fr.xlf
@@ -977,6 +977,11 @@
         <target state="translated">Cette expression convertit implicitement le type « {0} » en type « {1} ». Voir https://aka.ms/fsharp-implicit-convs.</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcSynTypeOrInvalidInDeclaration">
+        <source>SynType.Or is not permitted in this declaration</source>
+        <target state="new">SynType.Or is not permitted in this declaration</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcTraitHasMultipleSupportTypes">
         <source>The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</source>
         <target state="new">The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.it.xlf b/src/Compiler/xlf/FSComp.txt.it.xlf
index 46fe0bfdf02..4a810e60fcc 100644
--- a/src/Compiler/xlf/FSComp.txt.it.xlf
+++ b/src/Compiler/xlf/FSComp.txt.it.xlf
@@ -977,6 +977,11 @@
         <target state="translated">Questa espressione converte in modo implicito il tipo '{0}' nel tipo '{1}'. Vedere https://aka.ms/fsharp-implicit-convs.</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcSynTypeOrInvalidInDeclaration">
+        <source>SynType.Or is not permitted in this declaration</source>
+        <target state="new">SynType.Or is not permitted in this declaration</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcTraitHasMultipleSupportTypes">
         <source>The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</source>
         <target state="new">The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.ja.xlf b/src/Compiler/xlf/FSComp.txt.ja.xlf
index 58341cfee8b..0fc08e21cfe 100644
--- a/src/Compiler/xlf/FSComp.txt.ja.xlf
+++ b/src/Compiler/xlf/FSComp.txt.ja.xlf
@@ -977,6 +977,11 @@
         <target state="translated">この式は、型 '{0}' を型 '{1}' に暗黙的に変換します。https://aka.ms/fsharp-implicit-convs を参照してください。</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcSynTypeOrInvalidInDeclaration">
+        <source>SynType.Or is not permitted in this declaration</source>
+        <target state="new">SynType.Or is not permitted in this declaration</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcTraitHasMultipleSupportTypes">
         <source>The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</source>
         <target state="new">The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.ko.xlf b/src/Compiler/xlf/FSComp.txt.ko.xlf
index f17e7a6e178..9a5deaa0421 100644
--- a/src/Compiler/xlf/FSComp.txt.ko.xlf
+++ b/src/Compiler/xlf/FSComp.txt.ko.xlf
@@ -977,6 +977,11 @@
         <target state="translated">이 식은 암시적으로 '{0}' 형식을 '{1}' 형식으로 변환 합니다. https://aka.ms/fsharp-implicit-convs 참조</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcSynTypeOrInvalidInDeclaration">
+        <source>SynType.Or is not permitted in this declaration</source>
+        <target state="new">SynType.Or is not permitted in this declaration</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcTraitHasMultipleSupportTypes">
         <source>The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</source>
         <target state="new">The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.pl.xlf b/src/Compiler/xlf/FSComp.txt.pl.xlf
index 90f31614688..7f869a057f2 100644
--- a/src/Compiler/xlf/FSComp.txt.pl.xlf
+++ b/src/Compiler/xlf/FSComp.txt.pl.xlf
@@ -977,6 +977,11 @@
         <target state="translated">To wyrażenie bezwzględnie konwertuje typ "{0}" na typ "{1}". Zobacz https://aka.ms/fsharp-implicit-convs.</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcSynTypeOrInvalidInDeclaration">
+        <source>SynType.Or is not permitted in this declaration</source>
+        <target state="new">SynType.Or is not permitted in this declaration</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcTraitHasMultipleSupportTypes">
         <source>The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</source>
         <target state="new">The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.pt-BR.xlf b/src/Compiler/xlf/FSComp.txt.pt-BR.xlf
index 31ba7d3299e..165404290f0 100644
--- a/src/Compiler/xlf/FSComp.txt.pt-BR.xlf
+++ b/src/Compiler/xlf/FSComp.txt.pt-BR.xlf
@@ -977,6 +977,11 @@
         <target state="translated">Essa expressão converte implicitamente o tipo '{0}' ao tipo '{1}'. Consulte https://aka.ms/fsharp-implicit-convs.</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcSynTypeOrInvalidInDeclaration">
+        <source>SynType.Or is not permitted in this declaration</source>
+        <target state="new">SynType.Or is not permitted in this declaration</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcTraitHasMultipleSupportTypes">
         <source>The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</source>
         <target state="new">The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.ru.xlf b/src/Compiler/xlf/FSComp.txt.ru.xlf
index 3af5738e4d1..52876a45a7d 100644
--- a/src/Compiler/xlf/FSComp.txt.ru.xlf
+++ b/src/Compiler/xlf/FSComp.txt.ru.xlf
@@ -977,6 +977,11 @@
         <target state="translated">Это выражение неявно преобразует тип "{0}" в тип "{1}". См. сведения на странице https://aka.ms/fsharp-implicit-convs.</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcSynTypeOrInvalidInDeclaration">
+        <source>SynType.Or is not permitted in this declaration</source>
+        <target state="new">SynType.Or is not permitted in this declaration</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcTraitHasMultipleSupportTypes">
         <source>The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</source>
         <target state="new">The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.tr.xlf b/src/Compiler/xlf/FSComp.txt.tr.xlf
index c74d382e716..1c7303bf2fb 100644
--- a/src/Compiler/xlf/FSComp.txt.tr.xlf
+++ b/src/Compiler/xlf/FSComp.txt.tr.xlf
@@ -977,6 +977,11 @@
         <target state="translated">Bu ifade '{0}' türünü örtülü olarak '{1}' türüne dönüştürür. https://aka.ms/fsharp-implicit-convs adresine bakın.</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcSynTypeOrInvalidInDeclaration">
+        <source>SynType.Or is not permitted in this declaration</source>
+        <target state="new">SynType.Or is not permitted in this declaration</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcTraitHasMultipleSupportTypes">
         <source>The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</source>
         <target state="new">The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.zh-Hans.xlf b/src/Compiler/xlf/FSComp.txt.zh-Hans.xlf
index a1860f2bedc..45189c5d7dd 100644
--- a/src/Compiler/xlf/FSComp.txt.zh-Hans.xlf
+++ b/src/Compiler/xlf/FSComp.txt.zh-Hans.xlf
@@ -977,6 +977,11 @@
         <target state="translated">此表达式将类型“{0}”隐式转换为类型“{1}”。请参阅 https://aka.ms/fsharp-implicit-convs。</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcSynTypeOrInvalidInDeclaration">
+        <source>SynType.Or is not permitted in this declaration</source>
+        <target state="new">SynType.Or is not permitted in this declaration</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcTraitHasMultipleSupportTypes">
         <source>The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</source>
         <target state="new">The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.zh-Hant.xlf b/src/Compiler/xlf/FSComp.txt.zh-Hant.xlf
index 41e6735e44d..27040f48efe 100644
--- a/src/Compiler/xlf/FSComp.txt.zh-Hant.xlf
+++ b/src/Compiler/xlf/FSComp.txt.zh-Hant.xlf
@@ -977,6 +977,11 @@
         <target state="translated">此運算式將類型 '{0}' 隱含轉換為類型 '{1}'。請參閱 https://aka.ms/fsharp-implicit-convs。</target>
         <note />
       </trans-unit>
+      <trans-unit id="tcSynTypeOrInvalidInDeclaration">
+        <source>SynType.Or is not permitted in this declaration</source>
+        <target state="new">SynType.Or is not permitted in this declaration</target>
+        <note />
+      </trans-unit>
       <trans-unit id="tcTraitHasMultipleSupportTypes">
         <source>The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</source>
         <target state="new">The trait '{0}' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance.</target>
diff --git a/tests/FSharp.Compiler.Service.Tests/FSharp.CompilerService.SurfaceArea.netstandard.expected b/tests/FSharp.Compiler.Service.Tests/FSharp.CompilerService.SurfaceArea.netstandard.expected
index 9045f24ab29..d7f8a490d26 100644
--- a/tests/FSharp.Compiler.Service.Tests/FSharp.CompilerService.SurfaceArea.netstandard.expected
+++ b/tests/FSharp.Compiler.Service.Tests/FSharp.CompilerService.SurfaceArea.netstandard.expected
@@ -6744,10 +6744,10 @@ FSharp.Compiler.Syntax.SynExpr+TraitCall: FSharp.Compiler.Syntax.SynExpr argExpr
 FSharp.Compiler.Syntax.SynExpr+TraitCall: FSharp.Compiler.Syntax.SynExpr get_argExpr()
 FSharp.Compiler.Syntax.SynExpr+TraitCall: FSharp.Compiler.Syntax.SynMemberSig get_traitSig()
 FSharp.Compiler.Syntax.SynExpr+TraitCall: FSharp.Compiler.Syntax.SynMemberSig traitSig
+FSharp.Compiler.Syntax.SynExpr+TraitCall: FSharp.Compiler.Syntax.SynType get_supportTys()
+FSharp.Compiler.Syntax.SynExpr+TraitCall: FSharp.Compiler.Syntax.SynType supportTys
 FSharp.Compiler.Syntax.SynExpr+TraitCall: FSharp.Compiler.Text.Range get_range()
 FSharp.Compiler.Syntax.SynExpr+TraitCall: FSharp.Compiler.Text.Range range
-FSharp.Compiler.Syntax.SynExpr+TraitCall: Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynType] get_supportTys()
-FSharp.Compiler.Syntax.SynExpr+TraitCall: Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynType] supportTys
 FSharp.Compiler.Syntax.SynExpr+TryFinally: FSharp.Compiler.Syntax.DebugPointAtFinally finallyDebugPoint
 FSharp.Compiler.Syntax.SynExpr+TryFinally: FSharp.Compiler.Syntax.DebugPointAtFinally get_finallyDebugPoint()
 FSharp.Compiler.Syntax.SynExpr+TryFinally: FSharp.Compiler.Syntax.DebugPointAtTry get_tryDebugPoint()
@@ -7030,7 +7030,7 @@ FSharp.Compiler.Syntax.SynExpr: FSharp.Compiler.Syntax.SynExpr NewRecord(Microso
 FSharp.Compiler.Syntax.SynExpr: FSharp.Compiler.Syntax.SynExpr NewSequential(FSharp.Compiler.Syntax.DebugPointAtSequential, Boolean, FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynExpr: FSharp.Compiler.Syntax.SynExpr NewSequentialOrImplicitYield(FSharp.Compiler.Syntax.DebugPointAtSequential, FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynExpr: FSharp.Compiler.Syntax.SynExpr NewSet(FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Text.Range)
-FSharp.Compiler.Syntax.SynExpr: FSharp.Compiler.Syntax.SynExpr NewTraitCall(Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynType], FSharp.Compiler.Syntax.SynMemberSig, FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Text.Range)
+FSharp.Compiler.Syntax.SynExpr: FSharp.Compiler.Syntax.SynExpr NewTraitCall(FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Syntax.SynMemberSig, FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynExpr: FSharp.Compiler.Syntax.SynExpr NewTryFinally(FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Text.Range, FSharp.Compiler.Syntax.DebugPointAtTry, FSharp.Compiler.Syntax.DebugPointAtFinally, FSharp.Compiler.SyntaxTrivia.SynExprTryFinallyTrivia)
 FSharp.Compiler.Syntax.SynExpr: FSharp.Compiler.Syntax.SynExpr NewTryWith(FSharp.Compiler.Syntax.SynExpr, Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynMatchClause], FSharp.Compiler.Text.Range, FSharp.Compiler.Syntax.DebugPointAtTry, FSharp.Compiler.Syntax.DebugPointAtWith, FSharp.Compiler.SyntaxTrivia.SynExprTryWithTrivia)
 FSharp.Compiler.Syntax.SynExpr: FSharp.Compiler.Syntax.SynExpr NewTuple(Boolean, Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynExpr], Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Text.Range], FSharp.Compiler.Text.Range)
@@ -8512,6 +8512,14 @@ FSharp.Compiler.Syntax.SynType+MeasurePower: FSharp.Compiler.Syntax.SynType base
 FSharp.Compiler.Syntax.SynType+MeasurePower: FSharp.Compiler.Syntax.SynType get_baseMeasure()
 FSharp.Compiler.Syntax.SynType+MeasurePower: FSharp.Compiler.Text.Range get_range()
 FSharp.Compiler.Syntax.SynType+MeasurePower: FSharp.Compiler.Text.Range range
+FSharp.Compiler.Syntax.SynType+Or: FSharp.Compiler.Syntax.SynType get_lhsType()
+FSharp.Compiler.Syntax.SynType+Or: FSharp.Compiler.Syntax.SynType get_rhsType()
+FSharp.Compiler.Syntax.SynType+Or: FSharp.Compiler.Syntax.SynType lhsType
+FSharp.Compiler.Syntax.SynType+Or: FSharp.Compiler.Syntax.SynType rhsType
+FSharp.Compiler.Syntax.SynType+Or: FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia get_trivia()
+FSharp.Compiler.Syntax.SynType+Or: FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia trivia
+FSharp.Compiler.Syntax.SynType+Or: FSharp.Compiler.Text.Range get_range()
+FSharp.Compiler.Syntax.SynType+Or: FSharp.Compiler.Text.Range range
 FSharp.Compiler.Syntax.SynType+Paren: FSharp.Compiler.Syntax.SynType get_innerType()
 FSharp.Compiler.Syntax.SynType+Paren: FSharp.Compiler.Syntax.SynType innerType
 FSharp.Compiler.Syntax.SynType+Paren: FSharp.Compiler.Text.Range get_range()
@@ -8550,6 +8558,7 @@ FSharp.Compiler.Syntax.SynType+Tags: Int32 LongIdent
 FSharp.Compiler.Syntax.SynType+Tags: Int32 LongIdentApp
 FSharp.Compiler.Syntax.SynType+Tags: Int32 MeasureDivide
 FSharp.Compiler.Syntax.SynType+Tags: Int32 MeasurePower
+FSharp.Compiler.Syntax.SynType+Tags: Int32 Or
 FSharp.Compiler.Syntax.SynType+Tags: Int32 Paren
 FSharp.Compiler.Syntax.SynType+Tags: Int32 SignatureParameter
 FSharp.Compiler.Syntax.SynType+Tags: Int32 StaticConstant
@@ -8584,6 +8593,7 @@ FSharp.Compiler.Syntax.SynType: Boolean IsLongIdent
 FSharp.Compiler.Syntax.SynType: Boolean IsLongIdentApp
 FSharp.Compiler.Syntax.SynType: Boolean IsMeasureDivide
 FSharp.Compiler.Syntax.SynType: Boolean IsMeasurePower
+FSharp.Compiler.Syntax.SynType: Boolean IsOr
 FSharp.Compiler.Syntax.SynType: Boolean IsParen
 FSharp.Compiler.Syntax.SynType: Boolean IsSignatureParameter
 FSharp.Compiler.Syntax.SynType: Boolean IsStaticConstant
@@ -8602,6 +8612,7 @@ FSharp.Compiler.Syntax.SynType: Boolean get_IsLongIdent()
 FSharp.Compiler.Syntax.SynType: Boolean get_IsLongIdentApp()
 FSharp.Compiler.Syntax.SynType: Boolean get_IsMeasureDivide()
 FSharp.Compiler.Syntax.SynType: Boolean get_IsMeasurePower()
+FSharp.Compiler.Syntax.SynType: Boolean get_IsOr()
 FSharp.Compiler.Syntax.SynType: Boolean get_IsParen()
 FSharp.Compiler.Syntax.SynType: Boolean get_IsSignatureParameter()
 FSharp.Compiler.Syntax.SynType: Boolean get_IsStaticConstant()
@@ -8620,6 +8631,7 @@ FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType NewLongIdent(FSha
 FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType NewLongIdentApp(FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Syntax.SynLongIdent, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynType], Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType NewMeasureDivide(FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType NewMeasurePower(FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Syntax.SynRationalConst, FSharp.Compiler.Text.Range)
+FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType NewOr(FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia)
 FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType NewParen(FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType NewSignatureParameter(Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynAttributeList], Boolean, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.Ident], FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType NewStaticConstant(FSharp.Compiler.Syntax.SynConst, FSharp.Compiler.Text.Range)
@@ -8638,6 +8650,7 @@ FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType+LongIdent
 FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType+LongIdentApp
 FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType+MeasureDivide
 FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType+MeasurePower
+FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType+Or
 FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType+Paren
 FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType+SignatureParameter
 FSharp.Compiler.Syntax.SynType: FSharp.Compiler.Syntax.SynType+StaticConstant
@@ -8715,10 +8728,10 @@ FSharp.Compiler.Syntax.SynTypeConstraint+WhereTyparSubtypeOfType: FSharp.Compile
 FSharp.Compiler.Syntax.SynTypeConstraint+WhereTyparSubtypeOfType: FSharp.Compiler.Text.Range range
 FSharp.Compiler.Syntax.SynTypeConstraint+WhereTyparSupportsMember: FSharp.Compiler.Syntax.SynMemberSig get_memberSig()
 FSharp.Compiler.Syntax.SynTypeConstraint+WhereTyparSupportsMember: FSharp.Compiler.Syntax.SynMemberSig memberSig
+FSharp.Compiler.Syntax.SynTypeConstraint+WhereTyparSupportsMember: FSharp.Compiler.Syntax.SynType get_typars()
+FSharp.Compiler.Syntax.SynTypeConstraint+WhereTyparSupportsMember: FSharp.Compiler.Syntax.SynType typars
 FSharp.Compiler.Syntax.SynTypeConstraint+WhereTyparSupportsMember: FSharp.Compiler.Text.Range get_range()
 FSharp.Compiler.Syntax.SynTypeConstraint+WhereTyparSupportsMember: FSharp.Compiler.Text.Range range
-FSharp.Compiler.Syntax.SynTypeConstraint+WhereTyparSupportsMember: Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynType] get_typars()
-FSharp.Compiler.Syntax.SynTypeConstraint+WhereTyparSupportsMember: Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynType] typars
 FSharp.Compiler.Syntax.SynTypeConstraint+WhereTyparSupportsNull: FSharp.Compiler.Syntax.SynTypar get_typar()
 FSharp.Compiler.Syntax.SynTypeConstraint+WhereTyparSupportsNull: FSharp.Compiler.Syntax.SynTypar typar
 FSharp.Compiler.Syntax.SynTypeConstraint+WhereTyparSupportsNull: FSharp.Compiler.Text.Range get_range()
@@ -8757,7 +8770,7 @@ FSharp.Compiler.Syntax.SynTypeConstraint: FSharp.Compiler.Syntax.SynTypeConstrai
 FSharp.Compiler.Syntax.SynTypeConstraint: FSharp.Compiler.Syntax.SynTypeConstraint NewWhereTyparIsUnmanaged(FSharp.Compiler.Syntax.SynTypar, FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynTypeConstraint: FSharp.Compiler.Syntax.SynTypeConstraint NewWhereTyparIsValueType(FSharp.Compiler.Syntax.SynTypar, FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynTypeConstraint: FSharp.Compiler.Syntax.SynTypeConstraint NewWhereTyparSubtypeOfType(FSharp.Compiler.Syntax.SynTypar, FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Text.Range)
-FSharp.Compiler.Syntax.SynTypeConstraint: FSharp.Compiler.Syntax.SynTypeConstraint NewWhereTyparSupportsMember(Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynType], FSharp.Compiler.Syntax.SynMemberSig, FSharp.Compiler.Text.Range)
+FSharp.Compiler.Syntax.SynTypeConstraint: FSharp.Compiler.Syntax.SynTypeConstraint NewWhereTyparSupportsMember(FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Syntax.SynMemberSig, FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynTypeConstraint: FSharp.Compiler.Syntax.SynTypeConstraint NewWhereTyparSupportsNull(FSharp.Compiler.Syntax.SynTypar, FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynTypeConstraint: FSharp.Compiler.Syntax.SynTypeConstraint+Tags
 FSharp.Compiler.Syntax.SynTypeConstraint: FSharp.Compiler.Syntax.SynTypeConstraint+WhereSelfConstrained
@@ -9594,6 +9607,11 @@ FSharp.Compiler.SyntaxTrivia.SynTypeFunTrivia: FSharp.Compiler.Text.Range ArrowR
 FSharp.Compiler.SyntaxTrivia.SynTypeFunTrivia: FSharp.Compiler.Text.Range get_ArrowRange()
 FSharp.Compiler.SyntaxTrivia.SynTypeFunTrivia: System.String ToString()
 FSharp.Compiler.SyntaxTrivia.SynTypeFunTrivia: Void .ctor(FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia
+FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia: FSharp.Compiler.Text.Range OrKeyword
+FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia: FSharp.Compiler.Text.Range get_OrKeyword()
+FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia: System.String ToString()
+FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia: Void .ctor(FSharp.Compiler.Text.Range)
 FSharp.Compiler.SyntaxTrivia.SynUnionCaseTrivia
 FSharp.Compiler.SyntaxTrivia.SynUnionCaseTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] BarRange
 FSharp.Compiler.SyntaxTrivia.SynUnionCaseTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_BarRange()
diff --git a/tests/service/SyntaxTreeTests/SynTypeTests.fs b/tests/service/SyntaxTreeTests/SynTypeTests.fs
index 1ab5ed12e94..7f18521a995 100644
--- a/tests/service/SyntaxTreeTests/SynTypeTests.fs
+++ b/tests/service/SyntaxTreeTests/SynTypeTests.fs
@@ -49,3 +49,159 @@ type T =
       ])) ->
         assertRange (3, 14) (3, 56) mTuple
     | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``SynType.Or inside SynExpr.TraitCall`` () =
+    let parseResults =
+        getParseResults
+             """
+let inline (!!) (x: ^a) : ^b = ((^a or ^b): (static member op_Implicit: ^a -> ^b) x)
+ """
+
+    match parseResults with
+    | ParsedInput.ImplFile (ParsedImplFileInput (contents = [ SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+        SynModuleDecl.Let(bindings = [
+            SynBinding(expr =
+                SynExpr.Typed(expr =
+                    SynExpr.Paren(expr =
+                        SynExpr.TraitCall(supportTys =
+                            SynType.Paren(
+                                SynType.Or(
+                                    SynType.Var(range = mVar1),
+                                    SynType.Var(range = mVar2),
+                                    mOrType,
+                                    { OrKeyword = mOrWord }),
+                            mParen))
+                    )))
+        ]) ]) ])) ->
+        assertRange (2, 33) (2, 35) mVar1
+        assertRange (2, 36) (2, 38) mOrWord
+        assertRange (2, 39) (2, 41) mVar2
+        assertRange (2, 33) (2, 41) mOrType
+        assertRange (2, 32) (2, 42) mParen
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``SynType.Or inside SynTypeConstraint.WhereTyparSupportsMember`` () =
+    let parseResults =
+        getParseResults
+             """
+let inline f_StaticMethod<'T1, 'T2 when ('T1 or 'T2) : (static member StaticMethod: int -> int) >() : int = 
+    ()
+ """
+
+    match parseResults with
+    | ParsedInput.ImplFile (ParsedImplFileInput (contents = [ SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+        SynModuleDecl.Let(bindings = [
+            SynBinding(headPat =
+                SynPat.LongIdent(typarDecls = Some (SynValTyparDecls(typars = Some (SynTyparDecls.PostfixList(constraints = [
+                    SynTypeConstraint.WhereTyparSupportsMember(typars = SynType.Paren(
+                        SynType.Or(
+                            SynType.Var(range = mVar1),
+                            SynType.Var(range = mVar2),
+                            mOrType,
+                            { OrKeyword = mOrWord }),
+                        mParen
+                    ))
+                ]))))))
+        ]) ]) ])) ->
+        assertRange (2, 41) (2, 44) mVar1
+        assertRange (2, 45) (2, 47) mOrWord
+        assertRange (2, 48) (2, 51) mVar2
+        assertRange (2, 41) (2, 51) mOrType
+        assertRange (2, 40) (2, 52) mParen
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``Nested SynType.Or inside SynExpr.TraitCall`` () =
+    let parseResults =
+        getParseResults
+             """
+let inline (!!) (x: ^a * ^b) : ^c = ((^a or ^b or ^c): (static member op_Implicit: ^a * ^b -> ^c) x)
+ """
+
+    match parseResults with
+    | ParsedInput.ImplFile (ParsedImplFileInput (contents = [ SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+        SynModuleDecl.Let(bindings = [
+            SynBinding(expr =
+                SynExpr.Typed(expr =
+                    SynExpr.Paren(expr =
+                        SynExpr.TraitCall(supportTys =
+                            SynType.Paren(
+                                SynType.Or(
+                                    SynType.Or(
+                                        SynType.Var(range = mVarA),
+                                        SynType.Var(range = mVarB),
+                                        mOrType1,
+                                        { OrKeyword = mOrWord1 }
+                                    ),
+                                    SynType.Var(range = mVarC),
+                                    mOrType2,
+                                    { OrKeyword = mOrWord2 }),
+                            mParen))
+                    )))
+        ]) ]) ])) ->
+        assertRange (2, 38) (2, 40) mVarA
+        assertRange (2, 41) (2, 43) mOrWord1
+        assertRange (2, 44) (2, 46) mVarB
+        assertRange (2, 38) (2, 46) mOrType1
+        assertRange (2, 47) (2, 49) mOrWord2
+        assertRange (2, 50) (2, 52) mVarC
+        assertRange (2, 38) (2, 52) mOrType2
+        assertRange (2, 37) (2, 53) mParen
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+    
+[<Test>]
+let ``Single SynType inside SynExpr.TraitCall`` () =
+    let parseResults =
+        getParseResults
+             """
+type X =
+    static member inline replace< ^a, ^b, ^c when ^b: (static member replace: ^a * ^b -> ^c)>(a: ^a, f: ^b) =
+        (^b : (static member replace: ^a * ^b -> ^c) (a, f))
+ """
+
+    match parseResults with
+    | ParsedInput.ImplFile (ParsedImplFileInput (contents = [ SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+        SynModuleDecl.Types(typeDefns = [
+            SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                SynMemberDefn.Member(memberDefn =
+                    SynBinding(expr =
+                            SynExpr.Paren(expr =
+                                SynExpr.TraitCall(supportTys =
+                                    SynType.Var(range = mVar))
+                    )))
+            ]))
+        ]) ]) ])) ->
+        assertRange (4, 9) (4, 11) mVar
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``SynType.Or with appType on the right hand side`` () =
+    let parseResults =
+        getParseResults
+             """
+let inline f (x: 'T) = ((^T or int) : (static member A: int) ())
+ """
+
+    match parseResults with
+    | ParsedInput.ImplFile (ParsedImplFileInput (contents = [ SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+        SynModuleDecl.Let(bindings = [
+            SynBinding(expr =
+                    SynExpr.Paren(expr =
+                        SynExpr.TraitCall(supportTys =
+                            SynType.Paren(
+                                SynType.Or(
+                                    SynType.Var(range = mVar),
+                                    (SynType.LongIdent _ as appType),
+                                    mOrType,
+                                    { OrKeyword = mOrWord }),
+                            mParen))
+                    ))
+        ]) ]) ])) ->
+        assertRange (2, 25) (2,27) mVar
+        assertRange (2, 28) (2, 30) mOrWord
+        assertRange (2, 31) (2, 34) appType.Range
+        assertRange (2,25) (2, 34) mOrType
+        assertRange (2,24) (2, 35) mParen
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"

From 889709d8e506e6b707c6eaec5c310edda9c2be65 Mon Sep 17 00:00:00 2001
From: Rustam <rstm.sf@gmail.com>
Date: Wed, 12 Oct 2022 16:43:47 +0300
Subject: [PATCH 2/8] Change ty1.Equals(ty2) to call static op_Equality
 (#13028)

Co-authored-by: Vlad Zarytovskii <vzaritovsky@hotmail.com>
Co-authored-by: Don Syme <dsyme@users.noreply.github.com>
---
 src/Compiler/AbstractIL/ilreflect.fs          |   5 +-
 src/Compiler/TypedTree/TypeProviders.fs       |   2 +-
 src/Compiler/Utilities/sformat.fs             |   4 +-
 src/Compiler/Utilities/sr.fs                  |   2 +-
 src/FSharp.Build/FSharpEmbedResourceText.fs   |   2 +-
 src/FSharp.Core/Linq.fs                       |  11 +-
 src/FSharp.Core/Query.fs                      |  44 +--
 src/FSharp.Core/prim-types.fs                 | 319 +++++++++---------
 src/FSharp.Core/quotations.fs                 |   2 +-
 src/FSharp.Core/reflect.fs                    |   4 +-
 .../FSharp.DependencyManager.fs               |   2 +-
 tests/service/data/TestTP/ProvidedTypes.fs    |   2 +-
 12 files changed, 202 insertions(+), 197 deletions(-)

diff --git a/src/Compiler/AbstractIL/ilreflect.fs b/src/Compiler/AbstractIL/ilreflect.fs
index 0fc3e73e247..5cf3ec58222 100644
--- a/src/Compiler/AbstractIL/ilreflect.fs
+++ b/src/Compiler/AbstractIL/ilreflect.fs
@@ -412,7 +412,7 @@ module Zmap =
         | Some y -> y
         | None -> failwithf "Zmap.force: %s: x = %+A" str x
 
-let equalTypes (s: Type) (t: Type) = s.Equals t
+let equalTypes (s: Type) (t: Type) = Type.op_Equality (s, t)
 
 let equalTypeLists (tys1: Type list) (tys2: Type list) =
     List.lengthsEqAndForall2 equalTypes tys1 tys2
@@ -820,7 +820,8 @@ let TypeBuilderInstantiationT =
     ty
 
 let typeIsNotQueryable (ty: Type) =
-    (ty :? TypeBuilder) || ((ty.GetType()).Equals(TypeBuilderInstantiationT))
+    (ty :? TypeBuilder)
+    || Type.op_Equality (ty.GetType(), TypeBuilderInstantiationT)
 
 let queryableTypeGetField _emEnv (parentT: Type) (fref: ILFieldRef) =
     let res =
diff --git a/src/Compiler/TypedTree/TypeProviders.fs b/src/Compiler/TypedTree/TypeProviders.fs
index 662081a1f45..02f6fafd05d 100644
--- a/src/Compiler/TypedTree/TypeProviders.fs
+++ b/src/Compiler/TypedTree/TypeProviders.fs
@@ -415,7 +415,7 @@ type ProvidedType (x: Type, ctxt: ProvidedTypeContext) =
     member _.ApplyStaticArguments(provider: ITypeProvider, fullTypePathAfterArguments, staticArgs: obj[]) = 
         provider.ApplyStaticArguments(x, fullTypePathAfterArguments,  staticArgs) |> ProvidedType.Create ctxt
 
-    member _.IsVoid = (typeof<Void>.Equals x || (x.Namespace = "System" && x.Name = "Void"))
+    member _.IsVoid = (Type.op_Equality(x, typeof<Void>) || (x.Namespace = "System" && x.Name = "Void"))
 
     member _.IsGenericParameter = x.IsGenericParameter
 
diff --git a/src/Compiler/Utilities/sformat.fs b/src/Compiler/Utilities/sformat.fs
index 42b13e28ff9..303e2f968b5 100644
--- a/src/Compiler/Utilities/sformat.fs
+++ b/src/Compiler/Utilities/sformat.fs
@@ -455,9 +455,9 @@ module ReflectUtils =
         isNamedType (ty1)
         && if ty1.IsGenericType then
                ty2.IsGenericType
-               && (ty1.GetGenericTypeDefinition()).Equals(ty2.GetGenericTypeDefinition())
+               && Type.op_Equality (ty1.GetGenericTypeDefinition(), ty2.GetGenericTypeDefinition())
            else
-               ty1.Equals(ty2)
+               Type.op_Equality (ty1, ty2)
 
     let option = typedefof<obj option>
 
diff --git a/src/Compiler/Utilities/sr.fs b/src/Compiler/Utilities/sr.fs
index 245ed9841c2..77552a03b90 100644
--- a/src/Compiler/Utilities/sr.fs
+++ b/src/Compiler/Utilities/sr.fs
@@ -37,7 +37,7 @@ module internal DiagnosticMessage =
     let isFunctionType (ty1: System.Type) =
         isNamedType (ty1)
         && ty1.IsGenericType
-        && (ty1.GetGenericTypeDefinition()).Equals(funTyC)
+        && System.Type.op_Equality (ty1.GetGenericTypeDefinition(), funTyC)
 
     let rec destFunTy (ty: System.Type) =
         if isFunctionType ty then
diff --git a/src/FSharp.Build/FSharpEmbedResourceText.fs b/src/FSharp.Build/FSharpEmbedResourceText.fs
index 77002aa4f54..d8a3848ba27 100644
--- a/src/FSharp.Build/FSharpEmbedResourceText.fs
+++ b/src/FSharp.Build/FSharpEmbedResourceText.fs
@@ -289,7 +289,7 @@ open Printf
 
     static let isNamedType(ty:System.Type) = not (ty.IsArray ||  ty.IsByRef ||  ty.IsPointer)
     static let isFunctionType (ty1:System.Type)  =
-        isNamedType(ty1) && getTypeInfo(ty1).IsGenericType && (ty1.GetGenericTypeDefinition()).Equals(funTyC)
+        isNamedType(ty1) && getTypeInfo(ty1).IsGenericType && System.Type.op_Equality(ty1.GetGenericTypeDefinition(), funTyC)
 
     static let rec destFunTy (ty:System.Type) =
         if isFunctionType ty then
diff --git a/src/FSharp.Core/Linq.fs b/src/FSharp.Core/Linq.fs
index 33a1dd18265..6b62eccb93e 100644
--- a/src/FSharp.Core/Linq.fs
+++ b/src/FSharp.Core/Linq.fs
@@ -44,9 +44,9 @@ module LeafExpressionConverter =
     let equivHeadTypes (ty1:Type) (ty2:Type) =
         isNamedType(ty1) &&
         if ty1.IsGenericType then
-            ty2.IsGenericType && (ty1.GetGenericTypeDefinition()).Equals(ty2.GetGenericTypeDefinition())
+            ty2.IsGenericType && Type.op_Equality(ty1.GetGenericTypeDefinition(), ty2.GetGenericTypeDefinition())
         else
-            ty1.Equals(ty2)
+            Type.op_Equality(ty1, ty2)
 
     let isFunctionType typ = equivHeadTypes typ (typeof<(int -> int)>)
 
@@ -458,7 +458,7 @@ module LeafExpressionConverter =
             let converted = ConvExprToLinqInContext env x
 
             // Most of conversion scenarios in C# are covered by Expression.Convert
-            if x.Type.Equals toTy then converted // source and target types match - do nothing
+            if Type.op_Equality(x.Type, toTy) then converted // source and target types match - do nothing
             elif not (x.Type.IsValueType || toTy.IsValueType) && toTy.IsAssignableFrom x.Type then converted // converting reference type to supertype - do nothing
             else Expression.Convert(converted, toTy) |> asExpr // emit Expression.Convert
 
@@ -522,7 +522,10 @@ module LeafExpressionConverter =
                 Expression.New(ctor, argsR, [| for p in props -> (p :> MemberInfo) |]) |> asExpr
 
             // Do the same thing as C# compiler for string addition
-            | PlusQ (_, GenericArgs [|ty1; ty2; ty3|], [x1; x2]) when ty1 = typeof<string> && ty2 = typeof<string> && ty3 = typeof<string> ->
+            | PlusQ (_, GenericArgs [|ty1; ty2; ty3|], [x1; x2])
+                when Type.op_Equality(ty1, typeof<string>) &&
+                     Type.op_Equality(ty2, typeof<string>) &&
+                     Type.op_Equality(ty3, typeof<string>) ->
                  Expression.Add(ConvExprToLinqInContext env x1, ConvExprToLinqInContext env x2, StringConcat) |> asExpr
 
             // LanguagePrimitives.PhysicalEquality's generic constraint of both sides being the same reference type is already sufficient for Linq Expressions' requirements
diff --git a/src/FSharp.Core/Query.fs b/src/FSharp.Core/Query.fs
index ae11d3835a1..28a460619f6 100644
--- a/src/FSharp.Core/Query.fs
+++ b/src/FSharp.Core/Query.fs
@@ -440,7 +440,7 @@ module Query =
     let IsIEnumerableTy (ty: System.Type) = ty.IsGenericType && ty.GetGenericTypeDefinition() = IEnumerableTypeDef
 
     // Check a tag type on QuerySource is IQueryable
-    let qTyIsIQueryable (ty : System.Type) = not (ty.Equals(typeof<IEnumerable>))
+    let qTyIsIQueryable (ty : System.Type) = not (Type.op_Equality(ty, typeof<IEnumerable>))
 
     let FuncExprToDelegateExpr (srcTy, targetTy, v, body) =
         Expr.NewDelegate (Linq.Expressions.Expression.GetFuncType [| srcTy; targetTy |], [v], body)
@@ -588,21 +588,21 @@ module Query =
                 let selector = MakeImplicitExpressionConversion selector
                 let maker =
                     match resTyNoNullable with
-                    | ty when ty = typeof<double>  -> mq_double
-                    | ty when ty = typeof<single>  -> mq_single
-                    | ty when ty = typeof<decimal> -> mq_decimal
-                    | ty when ty = typeof<int32>   -> mq_int32
-                    | ty when ty = typeof<int64>   -> mq_int64
+                    | ty when Type.op_Equality(ty, typeof<double>)  -> mq_double
+                    | ty when Type.op_Equality(ty, typeof<single>)  -> mq_single
+                    | ty when Type.op_Equality(ty, typeof<decimal>) -> mq_decimal
+                    | ty when Type.op_Equality(ty, typeof<int32>)   -> mq_int32
+                    | ty when Type.op_Equality(ty, typeof<int64>)   -> mq_int64
                     | _ -> failDueToUnsupportedInputTypeInSumByOrAverageBy()
                 maker ([srcItemTy], [src; selector])
             else
                 // Try to dynamically invoke a LINQ method if one exists, since these may be optimized over arrays etc.
                 match resTyNoNullable with
-                | ty when ty = typeof<double>  -> me_double ([srcItemTy], [src; selector])
-                | ty when ty = typeof<single>  -> me_single ([srcItemTy], [src; selector])
-                | ty when ty = typeof<decimal> -> me_decimal ([srcItemTy], [src; selector])
-                | ty when ty = typeof<int32>   -> me_int32 ([srcItemTy], [src; selector])
-                | ty when ty = typeof<int64>   -> me_int64 ([srcItemTy], [src; selector])
+                | ty when Type.op_Equality(ty, typeof<double>)  -> me_double ([srcItemTy], [src; selector])
+                | ty when Type.op_Equality(ty, typeof<single>)  -> me_single ([srcItemTy], [src; selector])
+                | ty when Type.op_Equality(ty, typeof<decimal>) -> me_decimal ([srcItemTy], [src; selector])
+                | ty when Type.op_Equality(ty, typeof<int32>)   -> me_int32 ([srcItemTy], [src; selector])
+                | ty when Type.op_Equality(ty, typeof<int64>)   -> me_int64 ([srcItemTy], [src; selector])
                 | _ ->
                     // The F# implementation needs a QuerySource as a parameter.
                     let qTy = typeof<IEnumerable>
@@ -617,22 +617,22 @@ module Query =
                 let selector = FuncExprToLinqFunc2Expression (srcItemTy, resTy, v, res)
                 let caller =
                     match resTyNoNullable with
-                    | ty when ty = typeof<double>  -> cq_double
-                    | ty when ty = typeof<single>  -> cq_single
-                    | ty when ty = typeof<decimal> -> cq_decimal
-                    | ty when ty = typeof<int32>   -> cq_int32
-                    | ty when ty = typeof<int64>   -> cq_int64
+                    | ty when Type.op_Equality(ty, typeof<double>)  -> cq_double
+                    | ty when Type.op_Equality(ty, typeof<single>)  -> cq_single
+                    | ty when Type.op_Equality(ty, typeof<decimal>) -> cq_decimal
+                    | ty when Type.op_Equality(ty, typeof<int32>)   -> cq_int32
+                    | ty when Type.op_Equality(ty, typeof<int64>)   -> cq_int64
                     | _ -> failDueToUnsupportedInputTypeInSumByOrAverageBy()
                 caller ([srcItemTy], [src; box selector]) : obj
             else
                 // Try to dynamically invoke a LINQ method if one exists, since these may be optimized over arrays etc.
                 let linqMethOpt =
                     match resTyNoNullable with
-                    | ty when ty = typeof<double>  -> Some ce_double
-                    | ty when ty = typeof<single>  -> Some ce_single
-                    | ty when ty = typeof<decimal> -> Some ce_decimal
-                    | ty when ty = typeof<int32>   -> Some ce_int32
-                    | ty when ty = typeof<int64>   -> Some ce_int64
+                    | ty when Type.op_Equality(ty, typeof<double>)  -> Some ce_double
+                    | ty when Type.op_Equality(ty, typeof<single>)  -> Some ce_single
+                    | ty when Type.op_Equality(ty, typeof<decimal>) -> Some ce_decimal
+                    | ty when Type.op_Equality(ty, typeof<int32>)   -> Some ce_int32
+                    | ty when Type.op_Equality(ty, typeof<int64>)   -> Some ce_int64
                     | _ -> None
                 match linqMethOpt with
                 | Some ce ->
@@ -1617,7 +1617,7 @@ module Query =
                 let IQueryableTySpec = MakeIQueryableTy tyArg
                 // if result type of nested query is derived from IQueryable but not IQueryable itself (i.e. IOrderedQueryable)
                 // then add coercion to IQueryable so result type will match expected signature of QuerySource.Run
-                if (IQueryableTySpec.IsAssignableFrom replNestedQuery.Type) && not (IQueryableTySpec.Equals replNestedQuery.Type) then
+                if (IQueryableTySpec.IsAssignableFrom replNestedQuery.Type) && not (Type.op_Equality(IQueryableTySpec, replNestedQuery.Type)) then
                     Expr.Coerce (replNestedQuery, IQueryableTySpec)
                 else
                     replNestedQuery
diff --git a/src/FSharp.Core/prim-types.fs b/src/FSharp.Core/prim-types.fs
index 0489528c062..85befedcb4b 100644
--- a/src/FSharp.Core/prim-types.fs
+++ b/src/FSharp.Core/prim-types.fs
@@ -606,7 +606,7 @@ namespace Microsoft.FSharp.Core
                 then TypeNullnessSemantics_NullNever else
                 if not (typeof<'T>.IsDefined(typeof<CompilationMappingAttribute>, false))
                 then TypeNullnessSemantics_NullIsExtraValue
-                elif typeof<'T>.Equals(typeof<unit>) then 
+                elif Type.op_Equality (typeof<'T>, typeof<unit>) then 
                     TypeNullnessSemantics_NullTrueValue
                 elif typeof<Delegate>.IsAssignableFrom(typeof<'T>) then 
                     TypeNullnessSemantics_NullIsExtraValue
@@ -2098,22 +2098,22 @@ namespace Microsoft.FSharp.Core
         type FastGenericEqualityComparerTable<'T>() = 
             static let f : IEqualityComparer<'T> = 
                 match typeof<'T> with 
-                | ty when ty.Equals(typeof<bool>)       -> unboxPrim (box BoolIEquality)
-                | ty when ty.Equals(typeof<byte>)       -> unboxPrim (box ByteIEquality)
-                | ty when ty.Equals(typeof<int32>)      -> unboxPrim (box Int32IEquality)
-                | ty when ty.Equals(typeof<uint32>)     -> unboxPrim (box UInt32IEquality)
-                | ty when ty.Equals(typeof<char>)       -> unboxPrim (box CharIEquality)
-                | ty when ty.Equals(typeof<sbyte>)      -> unboxPrim (box SByteIEquality)
-                | ty when ty.Equals(typeof<int16>)      -> unboxPrim (box Int16IEquality)
-                | ty when ty.Equals(typeof<int64>)      -> unboxPrim (box Int64IEquality)
-                | ty when ty.Equals(typeof<nativeint>)  -> unboxPrim (box IntPtrIEquality)
-                | ty when ty.Equals(typeof<uint16>)     -> unboxPrim (box UInt16IEquality)
-                | ty when ty.Equals(typeof<uint64>)     -> unboxPrim (box UInt64IEquality)
-                | ty when ty.Equals(typeof<unativeint>) -> unboxPrim (box UIntPtrIEquality)
-                | ty when ty.Equals(typeof<float>)      -> unboxPrim (box FloatIEquality)
-                | ty when ty.Equals(typeof<float32>)    -> unboxPrim (box Float32IEquality)
-                | ty when ty.Equals(typeof<decimal>)    -> unboxPrim (box DecimalIEquality)
-                | ty when ty.Equals(typeof<string>)     -> unboxPrim (box StringIEquality)
+                | ty when Type.op_Equality(ty, typeof<bool>)       -> unboxPrim (box BoolIEquality)
+                | ty when Type.op_Equality(ty, typeof<byte>)       -> unboxPrim (box ByteIEquality)
+                | ty when Type.op_Equality(ty, typeof<int32>)      -> unboxPrim (box Int32IEquality)
+                | ty when Type.op_Equality(ty, typeof<uint32>)     -> unboxPrim (box UInt32IEquality)
+                | ty when Type.op_Equality(ty, typeof<char>)       -> unboxPrim (box CharIEquality)
+                | ty when Type.op_Equality(ty, typeof<sbyte>)      -> unboxPrim (box SByteIEquality)
+                | ty when Type.op_Equality(ty, typeof<int16>)      -> unboxPrim (box Int16IEquality)
+                | ty when Type.op_Equality(ty, typeof<int64>)      -> unboxPrim (box Int64IEquality)
+                | ty when Type.op_Equality(ty, typeof<nativeint>)  -> unboxPrim (box IntPtrIEquality)
+                | ty when Type.op_Equality(ty, typeof<uint16>)     -> unboxPrim (box UInt16IEquality)
+                | ty when Type.op_Equality(ty, typeof<uint64>)     -> unboxPrim (box UInt64IEquality)
+                | ty when Type.op_Equality(ty, typeof<unativeint>) -> unboxPrim (box UIntPtrIEquality)
+                | ty when Type.op_Equality(ty, typeof<float>)      -> unboxPrim (box FloatIEquality)
+                | ty when Type.op_Equality(ty, typeof<float32>)    -> unboxPrim (box Float32IEquality)
+                | ty when Type.op_Equality(ty, typeof<decimal>)    -> unboxPrim (box DecimalIEquality)
+                | ty when Type.op_Equality(ty, typeof<string>)     -> unboxPrim (box StringIEquality)
                 | _ -> MakeGenericEqualityComparer<'T>()
             static member Function : IEqualityComparer<'T> = f
 
@@ -2193,42 +2193,42 @@ namespace Microsoft.FSharp.Core
             // REVIEW: in a future version we could extend this to include additional types 
             static let fCanBeNull : IComparer<'T>  = 
                 match typeof<'T> with 
-                | ty when ty.Equals(typeof<nativeint>)  -> unboxPrim (box IntPtrComparer)
-                | ty when ty.Equals(typeof<unativeint>) -> unboxPrim (box UIntPtrComparer)
-                | ty when ty.Equals(typeof<byte>)       -> null    
-                | ty when ty.Equals(typeof<char>)       -> null    
-                | ty when ty.Equals(typeof<sbyte>)      -> null     
-                | ty when ty.Equals(typeof<int16>)      -> null    
-                | ty when ty.Equals(typeof<int32>)      -> null    
-                | ty when ty.Equals(typeof<int64>)      -> null    
-                | ty when ty.Equals(typeof<uint16>)     -> null    
-                | ty when ty.Equals(typeof<uint32>)     -> null    
-                | ty when ty.Equals(typeof<uint64>)     -> null    
-                | ty when ty.Equals(typeof<float>)      -> null    
-                | ty when ty.Equals(typeof<float32>)    -> null    
-                | ty when ty.Equals(typeof<decimal>)    -> null    
-                | ty when ty.Equals(typeof<string>)     -> unboxPrim (box StringComparer)
-                | ty when ty.Equals(typeof<bool>)       -> null
+                | ty when Type.op_Equality(ty, typeof<nativeint>)  -> unboxPrim (box IntPtrComparer)
+                | ty when Type.op_Equality(ty, typeof<unativeint>) -> unboxPrim (box UIntPtrComparer)
+                | ty when Type.op_Equality(ty, typeof<byte>)       -> null
+                | ty when Type.op_Equality(ty, typeof<char>)       -> null
+                | ty when Type.op_Equality(ty, typeof<sbyte>)      -> null
+                | ty when Type.op_Equality(ty, typeof<int16>)      -> null
+                | ty when Type.op_Equality(ty, typeof<int32>)      -> null
+                | ty when Type.op_Equality(ty, typeof<int64>)      -> null
+                | ty when Type.op_Equality(ty, typeof<uint16>)     -> null
+                | ty when Type.op_Equality(ty, typeof<uint32>)     -> null
+                | ty when Type.op_Equality(ty, typeof<uint64>)     -> null
+                | ty when Type.op_Equality(ty, typeof<float>)      -> null
+                | ty when Type.op_Equality(ty, typeof<float32>)    -> null
+                | ty when Type.op_Equality(ty, typeof<decimal>)    -> null
+                | ty when Type.op_Equality(ty, typeof<string>)     -> unboxPrim (box StringComparer)
+                | ty when Type.op_Equality(ty, typeof<bool>)       -> null
                 | _ -> MakeGenericComparer<'T>()
 
             static let f : IComparer<'T>  = 
                 match typeof<'T> with 
-                | ty when ty.Equals(typeof<byte>)       -> unboxPrim (box ByteComparer)
-                | ty when ty.Equals(typeof<char>)       -> unboxPrim (box CharComparer)
-                | ty when ty.Equals(typeof<sbyte>)      -> unboxPrim (box SByteComparer)
-                | ty when ty.Equals(typeof<int16>)      -> unboxPrim (box Int16Comparer)
-                | ty when ty.Equals(typeof<int32>)      -> unboxPrim (box Int32Comparer)
-                | ty when ty.Equals(typeof<int64>)      -> unboxPrim (box Int64Comparer)
-                | ty when ty.Equals(typeof<nativeint>)  -> unboxPrim (box IntPtrComparer)
-                | ty when ty.Equals(typeof<uint16>)     -> unboxPrim (box UInt16Comparer)
-                | ty when ty.Equals(typeof<uint32>)     -> unboxPrim (box UInt32Comparer)
-                | ty when ty.Equals(typeof<uint64>)     -> unboxPrim (box UInt64Comparer)
-                | ty when ty.Equals(typeof<unativeint>) -> unboxPrim (box UIntPtrComparer)
-                | ty when ty.Equals(typeof<float>)      -> unboxPrim (box FloatComparer)
-                | ty when ty.Equals(typeof<float32>)    -> unboxPrim (box Float32Comparer)
-                | ty when ty.Equals(typeof<decimal>)    -> unboxPrim (box DecimalComparer)
-                | ty when ty.Equals(typeof<string>)     -> unboxPrim (box StringComparer)
-                | ty when ty.Equals(typeof<bool>)       -> unboxPrim (box BoolComparer)
+                | ty when Type.op_Equality(ty, typeof<byte>)       -> unboxPrim (box ByteComparer)
+                | ty when Type.op_Equality(ty, typeof<char>)       -> unboxPrim (box CharComparer)
+                | ty when Type.op_Equality(ty, typeof<sbyte>)      -> unboxPrim (box SByteComparer)
+                | ty when Type.op_Equality(ty, typeof<int16>)      -> unboxPrim (box Int16Comparer)
+                | ty when Type.op_Equality(ty, typeof<int32>)      -> unboxPrim (box Int32Comparer)
+                | ty when Type.op_Equality(ty, typeof<int64>)      -> unboxPrim (box Int64Comparer)
+                | ty when Type.op_Equality(ty, typeof<nativeint>)  -> unboxPrim (box IntPtrComparer)
+                | ty when Type.op_Equality(ty, typeof<uint16>)     -> unboxPrim (box UInt16Comparer)
+                | ty when Type.op_Equality(ty, typeof<uint32>)     -> unboxPrim (box UInt32Comparer)
+                | ty when Type.op_Equality(ty, typeof<uint64>)     -> unboxPrim (box UInt64Comparer)
+                | ty when Type.op_Equality(ty, typeof<unativeint>) -> unboxPrim (box UIntPtrComparer)
+                | ty when Type.op_Equality(ty, typeof<float>)      -> unboxPrim (box FloatComparer)
+                | ty when Type.op_Equality(ty, typeof<float32>)    -> unboxPrim (box Float32Comparer)
+                | ty when Type.op_Equality(ty, typeof<decimal>)    -> unboxPrim (box DecimalComparer)
+                | ty when Type.op_Equality(ty, typeof<string>)     -> unboxPrim (box StringComparer)
+                | ty when Type.op_Equality(ty, typeof<bool>)       -> unboxPrim (box BoolComparer)
                 | _ -> 
                     // Review: There are situations where we should be able
                     // to return Generic.Comparer<'T>.Default here.
@@ -2450,46 +2450,46 @@ namespace Microsoft.FSharp.Core
         type GenericZeroDynamicImplTable<'T>() = 
             static let result : 'T = 
                 // The dynamic implementation
-                let aty = typeof<'T>
-                if   aty.Equals(typeof<sbyte>)      then unboxPrim<'T> (box 0y)
-                elif aty.Equals(typeof<int16>)      then unboxPrim<'T> (box 0s)
-                elif aty.Equals(typeof<int32>)      then unboxPrim<'T> (box 0)
-                elif aty.Equals(typeof<int64>)      then unboxPrim<'T> (box 0L)
-                elif aty.Equals(typeof<nativeint>)  then unboxPrim<'T> (box 0n)
-                elif aty.Equals(typeof<byte>)       then unboxPrim<'T> (box 0uy)
-                elif aty.Equals(typeof<uint16>)     then unboxPrim<'T> (box 0us)
-                elif aty.Equals(typeof<char>)       then unboxPrim<'T> (box '\000')
-                elif aty.Equals(typeof<uint32>)     then unboxPrim<'T> (box 0u)
-                elif aty.Equals(typeof<uint64>)     then unboxPrim<'T> (box 0UL)
-                elif aty.Equals(typeof<unativeint>) then unboxPrim<'T> (box 0un)
-                elif aty.Equals(typeof<decimal>)    then unboxPrim<'T> (box 0M)
-                elif aty.Equals(typeof<float>)      then unboxPrim<'T> (box 0.0)
-                elif aty.Equals(typeof<float32>)    then unboxPrim<'T> (box 0.0f)
+                let ty = typeof<'T>
+                if   Type.op_Equality(ty, typeof<sbyte>)      then unboxPrim<'T> (box 0y)
+                elif Type.op_Equality(ty, typeof<int16>)      then unboxPrim<'T> (box 0s)
+                elif Type.op_Equality(ty, typeof<int32>)      then unboxPrim<'T> (box 0)
+                elif Type.op_Equality(ty, typeof<int64>)      then unboxPrim<'T> (box 0L)
+                elif Type.op_Equality(ty, typeof<nativeint>)  then unboxPrim<'T> (box 0n)
+                elif Type.op_Equality(ty, typeof<byte>)       then unboxPrim<'T> (box 0uy)
+                elif Type.op_Equality(ty, typeof<uint16>)     then unboxPrim<'T> (box 0us)
+                elif Type.op_Equality(ty, typeof<char>)       then unboxPrim<'T> (box '\000')
+                elif Type.op_Equality(ty, typeof<uint32>)     then unboxPrim<'T> (box 0u)
+                elif Type.op_Equality(ty, typeof<uint64>)     then unboxPrim<'T> (box 0UL)
+                elif Type.op_Equality(ty, typeof<unativeint>) then unboxPrim<'T> (box 0un)
+                elif Type.op_Equality(ty, typeof<decimal>)    then unboxPrim<'T> (box 0M)
+                elif Type.op_Equality(ty, typeof<float>)      then unboxPrim<'T> (box 0.0)
+                elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<'T> (box 0.0f)
                 else 
-                   let pinfo = aty.GetProperty("Zero")
+                   let pinfo = ty.GetProperty("Zero")
                    unboxPrim<'T> (pinfo.GetValue(null,null))
             static member Result : 'T = result
                    
         type GenericOneDynamicImplTable<'T>() = 
             static let result : 'T = 
                 // The dynamic implementation
-                let aty = typeof<'T>
-                if   aty.Equals(typeof<sbyte>)      then unboxPrim<'T> (box 1y)
-                elif aty.Equals(typeof<int16>)      then unboxPrim<'T> (box 1s)
-                elif aty.Equals(typeof<int32>)      then unboxPrim<'T> (box 1)
-                elif aty.Equals(typeof<int64>)      then unboxPrim<'T> (box 1L)
-                elif aty.Equals(typeof<nativeint>)  then unboxPrim<'T> (box 1n)
-                elif aty.Equals(typeof<byte>)       then unboxPrim<'T> (box 1uy)
-                elif aty.Equals(typeof<uint16>)     then unboxPrim<'T> (box 1us)
-                elif aty.Equals(typeof<char>)       then unboxPrim<'T> (box '\001')
-                elif aty.Equals(typeof<uint32>)     then unboxPrim<'T> (box 1u)
-                elif aty.Equals(typeof<uint64>)     then unboxPrim<'T> (box 1UL)
-                elif aty.Equals(typeof<unativeint>) then unboxPrim<'T> (box 1un)
-                elif aty.Equals(typeof<decimal>)    then unboxPrim<'T> (box 1M)
-                elif aty.Equals(typeof<float>)      then unboxPrim<'T> (box 1.0)
-                elif aty.Equals(typeof<float32>)    then unboxPrim<'T> (box 1.0f)
+                let ty = typeof<'T>
+                if   Type.op_Equality(ty, typeof<sbyte>)      then unboxPrim<'T> (box 1y)
+                elif Type.op_Equality(ty, typeof<int16>)      then unboxPrim<'T> (box 1s)
+                elif Type.op_Equality(ty, typeof<int32>)      then unboxPrim<'T> (box 1)
+                elif Type.op_Equality(ty, typeof<int64>)      then unboxPrim<'T> (box 1L)
+                elif Type.op_Equality(ty, typeof<nativeint>)  then unboxPrim<'T> (box 1n)
+                elif Type.op_Equality(ty, typeof<byte>)       then unboxPrim<'T> (box 1uy)
+                elif Type.op_Equality(ty, typeof<uint16>)     then unboxPrim<'T> (box 1us)
+                elif Type.op_Equality(ty, typeof<char>)       then unboxPrim<'T> (box '\001')
+                elif Type.op_Equality(ty, typeof<uint32>)     then unboxPrim<'T> (box 1u)
+                elif Type.op_Equality(ty, typeof<uint64>)     then unboxPrim<'T> (box 1UL)
+                elif Type.op_Equality(ty, typeof<unativeint>) then unboxPrim<'T> (box 1un)
+                elif Type.op_Equality(ty, typeof<decimal>)    then unboxPrim<'T> (box 1M)
+                elif Type.op_Equality(ty, typeof<float>)      then unboxPrim<'T> (box 1.0)
+                elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<'T> (box 1.0f)
                 else 
-                   let pinfo = aty.GetProperty("One")
+                   let pinfo = ty.GetProperty("One")
                    unboxPrim<'T> (pinfo.GetValue(null,null))
 
             static member Result : 'T = result
@@ -2604,7 +2604,7 @@ namespace Microsoft.FSharp.Core
 
                     let ameth = aty.GetSingleStaticMethodByTypes(opName, [| aty; bty |])
                     let bmeth = 
-                        if aty.Equals(bty) then null else 
+                        if Type.op_Equality(aty, bty) then null else
                         bty.GetSingleStaticMethodByTypes(opName, [| aty; bty |])
                     match ameth, bmeth with
                     | null, null -> raise (NotSupportedException (SR.GetString(SR.dyInvOpAddCoerce)))
@@ -4175,7 +4175,7 @@ namespace Microsoft.FSharp.Core
         let Failure message = new Exception(message)
         
         [<CompiledName("FailurePattern")>]
-        let (|Failure|_|) (error: exn) = if error.GetType().Equals(typeof<Exception>) then Some error.Message else None
+        let (|Failure|_|) (error: exn) = if Type.op_Equality(error.GetType(), typeof<Exception>) then Some error.Message else None
 
         let inline (<) x y = GenericLessThan x y
 
@@ -5002,7 +5002,7 @@ namespace Microsoft.FSharp.Core
                 when ^T : string     = not (# "clt" (String.CompareOrdinal((# "" x : string #),(# "" y : string #))) 0 : bool #)             
                 when ^T : ^T = ((^T or ^U): (static member (>=) : ^T * ^U -> bool) (x,y))
 
-            /// Static greater-than-or-equal with static optimizations for some well-known cases.
+            /// Static equal with static optimizations for some well-known cases.
             let inline (=) (x:^T) (y:^T) = 
                 EqualityDynamic<(^T), (^T), bool> x y
                 when ^T : bool    = (# "ceq" x y : bool #)
@@ -5023,6 +5023,7 @@ namespace Microsoft.FSharp.Core
                 when ^T : decimal = Decimal.op_Equality((# "" x:decimal #), (# "" y:decimal #))
                 when ^T : ^T = (^T : (static member (=) : ^T * ^T -> bool) (x,y))
 
+            /// Static unequal with static optimizations for some well-known cases.
             let inline (<>) (x:^T) (y:^T) = 
                 InequalityDynamic<(^T), (^T), bool> x y
                 when ^T : bool    = not (# "ceq" x y : bool #)
@@ -6472,181 +6473,181 @@ namespace Microsoft.FSharp.Core
 
             type AbsDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if   aty.Equals(typeof<sbyte>)      then unboxPrim<_>(fun (x:sbyte)     -> absImpl x)
-                    elif aty.Equals(typeof<int16>)      then unboxPrim<_>(fun (x:int16)     -> absImpl x)
-                    elif aty.Equals(typeof<int32>)      then unboxPrim<_>(fun (x:int32)     -> absImpl x)
-                    elif aty.Equals(typeof<int64>)      then unboxPrim<_>(fun (x:int64)     -> absImpl x)
-                    elif aty.Equals(typeof<nativeint>)  then unboxPrim<_>(fun (x:nativeint) -> absImpl x)
-                    elif aty.Equals(typeof<float>)      then unboxPrim<_>(fun (x:float)     -> absImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> absImpl x)
-                    elif aty.Equals(typeof<decimal>)    then unboxPrim<_>(fun (x:decimal)   -> absImpl x)
+                    let ty = typeof<'T>
+                    if   Type.op_Equality(ty, typeof<sbyte>)      then unboxPrim<_>(fun (x:sbyte)     -> absImpl x)
+                    elif Type.op_Equality(ty, typeof<int16>)      then unboxPrim<_>(fun (x:int16)     -> absImpl x)
+                    elif Type.op_Equality(ty, typeof<int32>)      then unboxPrim<_>(fun (x:int32)     -> absImpl x)
+                    elif Type.op_Equality(ty, typeof<int64>)      then unboxPrim<_>(fun (x:int64)     -> absImpl x)
+                    elif Type.op_Equality(ty, typeof<nativeint>)  then unboxPrim<_>(fun (x:nativeint) -> absImpl x)
+                    elif Type.op_Equality(ty, typeof<float>)      then unboxPrim<_>(fun (x:float)     -> absImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> absImpl x)
+                    elif Type.op_Equality(ty, typeof<decimal>)    then unboxPrim<_>(fun (x:decimal)   -> absImpl x)
                     else UnaryDynamicImpl "Abs" 
                 static member Result : ('T -> 'T) = result
 
             type AcosDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> acosImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> acosImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> acosImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> acosImpl x)
                     else UnaryDynamicImpl "Acos" 
                 static member Result : ('T -> 'T) = result
 
             type AsinDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> asinImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> asinImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> asinImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> asinImpl x)
                     else UnaryDynamicImpl "Asin" 
                 static member Result : ('T -> 'T) = result
 
             type AtanDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> atanImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> atanImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> atanImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> atanImpl x)
                     else UnaryDynamicImpl "Atan" 
                 static member Result : ('T -> 'T) = result
 
             type Atan2DynamicImplTable<'T,'U>() = 
                 static let result : ('T -> 'T -> 'U) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)  (y:float)   -> atan2Impl x y)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32) (y:float32)  -> atan2Impl x y)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)  (y:float)      -> atan2Impl x y)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32) (y:float32)   -> atan2Impl x y)
                     else BinaryDynamicImpl "Atan2"
                 static member Result : ('T -> 'T -> 'U) = result
 
             type CeilingDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> ceilImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> ceilImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> ceilImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> ceilImpl x)
                     else UnaryDynamicImpl "Ceiling" 
                 static member Result : ('T -> 'T) = result
 
             type ExpDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> expImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> expImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> expImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> expImpl x)
                     else UnaryDynamicImpl "Exp" 
                 static member Result : ('T -> 'T) = result
 
             type FloorDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> floorImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> floorImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> floorImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> floorImpl x)
                     else UnaryDynamicImpl "Floor" 
                 static member Result : ('T -> 'T) = result
 
             type TruncateDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> truncateImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> truncateImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> truncateImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> truncateImpl x)
                     else UnaryDynamicImpl "Truncate" 
                 static member Result : ('T -> 'T) = result
 
             type RoundDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> roundImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> roundImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> roundImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> roundImpl x)
                     else UnaryDynamicImpl "Round" 
                 static member Result : ('T -> 'T) = result
 
             type SignDynamicImplTable<'T>() = 
                 static let result : ('T -> int) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> signImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> signImpl x)
-                    elif aty.Equals(typeof<nativeint>)    then unboxPrim<_>(fun (x:nativeint)   -> signImpl x)
-                    elif aty.Equals(typeof<decimal>)    then unboxPrim<_>(fun (x:decimal)   -> signImpl x)
-                    elif aty.Equals(typeof<int16>)    then unboxPrim<_>(fun (x:int16)   -> signImpl x)
-                    elif aty.Equals(typeof<int32>)    then unboxPrim<_>(fun (x:int32)   -> signImpl x)
-                    elif aty.Equals(typeof<int64>)    then unboxPrim<_>(fun (x:int64)   -> signImpl x)
-                    elif aty.Equals(typeof<sbyte>)    then unboxPrim<_>(fun (x:sbyte)   -> signImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)       -> signImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)     -> signImpl x)
+                    elif Type.op_Equality(ty, typeof<nativeint>)  then unboxPrim<_>(fun (x:nativeint)   -> signImpl x)
+                    elif Type.op_Equality(ty, typeof<decimal>)    then unboxPrim<_>(fun (x:decimal)     -> signImpl x)
+                    elif Type.op_Equality(ty, typeof<int16>)      then unboxPrim<_>(fun (x:int16)       -> signImpl x)
+                    elif Type.op_Equality(ty, typeof<int32>)      then unboxPrim<_>(fun (x:int32)       -> signImpl x)
+                    elif Type.op_Equality(ty, typeof<int64>)      then unboxPrim<_>(fun (x:int64)       -> signImpl x)
+                    elif Type.op_Equality(ty, typeof<sbyte>)      then unboxPrim<_>(fun (x:sbyte)       -> signImpl x)
                     else UnaryDynamicImpl "Sign" 
                 static member Result : ('T -> int) = result
 
             type LogDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> logImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> logImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> logImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> logImpl x)
                     else UnaryDynamicImpl "Log" 
                 static member Result : ('T -> 'T) = result
 
             type Log10DynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> log10Impl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> log10Impl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> log10Impl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> log10Impl x)
                     else UnaryDynamicImpl "Log10" 
                 static member Result : ('T -> 'T) = result
 
             type SqrtDynamicImplTable<'T,'U>() = 
                 static let result : ('T -> 'U) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> sqrtImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> sqrtImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> sqrtImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> sqrtImpl x)
                     else UnaryDynamicImpl "Sqrt" 
                 static member Result : ('T -> 'U) = result
 
             type CosDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> cosImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> cosImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> cosImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> cosImpl x)
                     else UnaryDynamicImpl "Cos" 
                 static member Result : ('T -> 'T) = result
 
             type CoshDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> coshImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> coshImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> coshImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> coshImpl x)
                     else UnaryDynamicImpl "Cosh" 
                 static member Result : ('T -> 'T) = result
 
             type SinDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> sinImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> sinImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> sinImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> sinImpl x)
                     else UnaryDynamicImpl "Sin" 
                 static member Result : ('T -> 'T) = result
 
             type SinhDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> sinhImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> sinhImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> sinhImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> sinhImpl x)
                     else UnaryDynamicImpl "Sinh" 
                 static member Result : ('T -> 'T) = result
 
             type TanDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> tanImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> tanImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> tanImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> tanImpl x)
                     else UnaryDynamicImpl "Tan" 
                 static member Result : ('T -> 'T) = result
 
             type TanhDynamicImplTable<'T>() = 
                 static let result : ('T -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)     -> tanhImpl x)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> tanhImpl x)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)     -> tanhImpl x)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32)   -> tanhImpl x)
                     else UnaryDynamicImpl "Tanh" 
                 static member Result : ('T -> 'T) = result
 
             type PowDynamicImplTable<'T,'U>() = 
                 static let result : ('T -> 'U -> 'T) = 
-                    let aty = typeof<'T>
-                    if aty.Equals(typeof<float>)        then unboxPrim<_>(fun (x:float)   (y:float)  -> powImpl x y)
-                    elif aty.Equals(typeof<float32>)    then unboxPrim<_>(fun (x:float32) (y:float32)  -> powImpl x y)
+                    let ty = typeof<'T>
+                    if Type.op_Equality(ty, typeof<float>)        then unboxPrim<_>(fun (x:float)   (y:float)    -> powImpl x y)
+                    elif Type.op_Equality(ty, typeof<float32>)    then unboxPrim<_>(fun (x:float32) (y:float32)  -> powImpl x y)
                     else BinaryDynamicImpl "Pow" 
                 static member Result : ('T -> 'U -> 'T) = result
 
diff --git a/src/FSharp.Core/quotations.fs b/src/FSharp.Core/quotations.fs
index c3c7317e522..20f2e8ca06b 100644
--- a/src/FSharp.Core/quotations.fs
+++ b/src/FSharp.Core/quotations.fs
@@ -1403,7 +1403,7 @@ module Patterns =
         | Ambiguous of 'R
 
     let typeEquals (ty1: Type) (ty2: Type) =
-        ty1.Equals ty2
+        Type.op_Equality (ty1, ty2)
 
     let typesEqual (tys1: Type list) (tys2: Type list) =
         (tys1.Length = tys2.Length) && List.forall2 typeEquals tys1 tys2
diff --git a/src/FSharp.Core/reflect.fs b/src/FSharp.Core/reflect.fs
index 76dbb87c490..e9522f68c99 100644
--- a/src/FSharp.Core/reflect.fs
+++ b/src/FSharp.Core/reflect.fs
@@ -43,9 +43,9 @@ module internal Impl =
         isNamedType ty1
         && if ty1.IsGenericType then
                ty2.IsGenericType
-               && (ty1.GetGenericTypeDefinition()).Equals(ty2.GetGenericTypeDefinition())
+               && Type.op_Equality (ty1.GetGenericTypeDefinition(), ty2.GetGenericTypeDefinition())
            else
-               ty1.Equals ty2
+               Type.op_Equality (ty1, ty2)
 
     let func = typedefof<(obj -> obj)>
 
diff --git a/src/FSharp.DependencyManager.Nuget/FSharp.DependencyManager.fs b/src/FSharp.DependencyManager.Nuget/FSharp.DependencyManager.fs
index 294cf2df55d..0740f5aa753 100644
--- a/src/FSharp.DependencyManager.Nuget/FSharp.DependencyManager.fs
+++ b/src/FSharp.DependencyManager.Nuget/FSharp.DependencyManager.fs
@@ -132,7 +132,7 @@ module FSharpDependencyManager =
                 | Some "timeout", None -> raise (ArgumentException(SR.missingTimeoutValue ()))
                 | Some "timeout", value ->
                     match value with
-                    | Some v when v.GetType() = typeof<string> ->
+                    | Some v when Type.op_Equality (v.GetType(), typeof<string>) ->
                         let parsed, value = Int32.TryParse(v)
 
                         if parsed && value >= 0 then
diff --git a/tests/service/data/TestTP/ProvidedTypes.fs b/tests/service/data/TestTP/ProvidedTypes.fs
index c13961cbc27..4e7a7604c6b 100644
--- a/tests/service/data/TestTP/ProvidedTypes.fs
+++ b/tests/service/data/TestTP/ProvidedTypes.fs
@@ -76,7 +76,7 @@ module Utils =
     /// General implementation of .Equals(Type) logic for System.Type over symbol types. You can use this with other types too.
     let rec eqTypes (ty1: Type) (ty2: Type) =
         if Object.ReferenceEquals(ty1, ty2) then true
-        elif ty1.IsGenericTypeDefinition then ty2.IsGenericTypeDefinition && ty1.Equals(ty2)
+        elif ty1.IsGenericTypeDefinition then ty2.IsGenericTypeDefinition && Type.op_Equality(ty1, ty2)
         elif ty1.IsGenericType then ty2.IsGenericType && not ty2.IsGenericTypeDefinition && eqTypes (ty1.GetGenericTypeDefinition()) (ty2.GetGenericTypeDefinition()) && lengthsEqAndForall2 (ty1.GetGenericArguments()) (ty2.GetGenericArguments()) eqTypes
         elif ty1.IsArray then ty2.IsArray && ty1.GetArrayRank() = ty2.GetArrayRank() && eqTypes (ty1.GetElementType()) (ty2.GetElementType())
         elif ty1.IsPointer then ty2.IsPointer && eqTypes (ty1.GetElementType()) (ty2.GetElementType())

From 434391e887c0dbb12093243ebcba4e88066d708d Mon Sep 17 00:00:00 2001
From: Tomas Grosup <tomasgrosup@microsoft.com>
Date: Thu, 13 Oct 2022 10:23:46 +0200
Subject: [PATCH 3/8] FsharpCompilerService benchmark for changes in a cascade
 of files referencing each other (#14096)

* Generating cascading project
* Benchmark attributes added
---
 .../FSharp.Compiler.Benchmarks.fsproj         |   1 +
 .../FileCascadeBenchmarks.fs                  | 118 ++++++++++++++++++
 2 files changed, 119 insertions(+)
 create mode 100644 tests/benchmarks/FCSBenchmarks/CompilerServiceBenchmarks/FileCascadeBenchmarks.fs

diff --git a/tests/benchmarks/FCSBenchmarks/CompilerServiceBenchmarks/FSharp.Compiler.Benchmarks.fsproj b/tests/benchmarks/FCSBenchmarks/CompilerServiceBenchmarks/FSharp.Compiler.Benchmarks.fsproj
index 4bdb142e62b..d1187649935 100644
--- a/tests/benchmarks/FCSBenchmarks/CompilerServiceBenchmarks/FSharp.Compiler.Benchmarks.fsproj
+++ b/tests/benchmarks/FCSBenchmarks/CompilerServiceBenchmarks/FSharp.Compiler.Benchmarks.fsproj
@@ -17,6 +17,7 @@
     <Compile Include="SourceText.fs" />
     <Compile Include="DecentlySizedStandAloneFileBenchmark.fs" />
     <Compile Include="CompilerServiceBenchmarks.fs" />
+    <Compile Include="FileCascadeBenchmarks.fs" />
     <Compile Include="Program.fs" />
   </ItemGroup>
 
diff --git a/tests/benchmarks/FCSBenchmarks/CompilerServiceBenchmarks/FileCascadeBenchmarks.fs b/tests/benchmarks/FCSBenchmarks/CompilerServiceBenchmarks/FileCascadeBenchmarks.fs
new file mode 100644
index 00000000000..746f81065b7
--- /dev/null
+++ b/tests/benchmarks/FCSBenchmarks/CompilerServiceBenchmarks/FileCascadeBenchmarks.fs
@@ -0,0 +1,118 @@
+namespace FSharp.Compiler.Benchmarks
+
+open System
+open System.IO
+open System.Text
+open FSharp.Compiler.CodeAnalysis
+open FSharp.Compiler.Diagnostics
+open FSharp.Compiler.EditorServices
+open FSharp.Compiler.Text
+open FSharp.Compiler.AbstractIL.IL
+open FSharp.Compiler.AbstractIL.ILBinaryReader
+open BenchmarkDotNet.Attributes
+open FSharp.Compiler.Benchmarks
+open Microsoft.CodeAnalysis.Text
+open BenchmarkDotNet.Order
+open BenchmarkDotNet.Mathematics
+
+[<AutoOpen>]
+module private CascadeProjectHelpers =
+        
+    let createProject files projectFilename =       
+        {
+            ProjectFileName = projectFilename
+            ProjectId = None
+            SourceFiles = files
+            OtherOptions =  [|"--optimize+" |] 
+            ReferencedProjects = [||]
+            IsIncompleteTypeCheckEnvironment = false
+            UseScriptResolutionRules = false
+            LoadTime = DateTime()
+            UnresolvedReferences = None
+            OriginalLoadReferences = []
+            Stamp = Some 0L (* set the stamp to 0L on each run so we don't evaluate the whole project again *)
+        }
+
+    let baselineModule =
+        $"""
+module Benchmark0
+let returnValue = 5
+let myFunc0 () = 5"""
+
+    let generateSourceCode number =
+        $"""
+module Benchmark%i{number}
+open Benchmark%i{number-1}
+let myFunc%i{number} () = myFunc%i{number-1}()
+//$COMMENTAREA$"""
+
+[<MemoryDiagnoser>]
+[<LongRunJob>]
+[<Orderer(SummaryOrderPolicy.FastestToSlowest)>]
+[<RankColumn(NumeralSystem.Roman)>]
+type FileCascadeBenchmarks() = 
+    let mutable project : FSharpProjectOptions option = None
+
+    let getProject() = project.Value
+    
+    let checker = FSharpChecker.Create(projectCacheSize = 5, enableParallelCheckingWithSignatureFiles = true, parallelReferenceResolution = true)
+    let filesToCreate = 64
+
+    let mutable finalFileContents = SourceText.ofString ""
+        
+    [<GlobalSetup>]
+    member _.Setup() =
+        let projectFolder = Directory.CreateDirectory(Path.Combine(Directory.GetCurrentDirectory(),"CascadeBenchmarkProject"))                    
+        if(projectFolder.Exists) then
+            do projectFolder.Delete(recursive=true)
+        do Directory.CreateDirectory(projectFolder.FullName) |> ignore
+
+        let inProjectFolder fileName = Path.Combine(projectFolder.FullName,fileName)
+
+        File.WriteAllText(inProjectFolder "Benchmark0.fs",baselineModule)
+        for i = 1 to filesToCreate do
+            File.WriteAllText(inProjectFolder $"Benchmark%i{i}.fs", generateSourceCode i)
+
+        let dllFileName = inProjectFolder "CascadingBenchMark.dll"
+        let allSourceCodeFiles = [| for i in 0 .. filesToCreate -> inProjectFolder $"Benchmark%i{i}.fs"|]
+        let x = createProject allSourceCodeFiles dllFileName
+        project <- Some x
+        finalFileContents <- generateSourceCode filesToCreate |> SourceText.ofString
+
+
+    member x.ChangeFile(fileIndex:int, action) = 
+        let project = getProject()
+        let fileName = project.SourceFiles.[fileIndex]
+        let fullOriginalSource = File.ReadAllText(fileName)
+        try
+            File.WriteAllText(fileName, fullOriginalSource.Replace("$COMMENTAREA$","$FILEMODIFIED"))
+            action()
+        finally
+            File.WriteAllText(fileName,fullOriginalSource)
+
+    member x.CheckFinalFile () =
+        let project = getProject()
+        let lastFile = project.SourceFiles |> Array.last
+        checker.ParseAndCheckFileInProject(lastFile,999,finalFileContents,project)
+               
+    [<Benchmark>]
+    member x.ParseProjectAsIs() =
+        x.CheckFinalFile()
+
+    [<Benchmark(Baseline=true)>]
+    member x.ParseProjectWithFullCacheClear() =
+        checker.ClearCache([getProject()])
+        checker.InvalidateConfiguration(getProject())
+        x.CheckFinalFile()
+
+    [<Benchmark>]
+    member x.ParseProjectWithChangingFirstFile() =
+        x.ChangeFile(fileIndex=0, action= fun () -> x.CheckFinalFile())  
+
+    [<Benchmark>]
+    member x.ParseProjectWithChanging25thPercentileFile() =
+        x.ChangeFile(fileIndex=filesToCreate/4, action= fun () -> x.CheckFinalFile())  
+
+    [<Benchmark>]
+    member x.ParseProjectWithChangingMiddleFile() =
+        x.ChangeFile(fileIndex=filesToCreate/2, action= fun () -> x.CheckFinalFile())  
\ No newline at end of file

From 5f54b69c67b3bae7321906ea35874ff33457cdb9 Mon Sep 17 00:00:00 2001
From: Martin521 <29605222+Martin521@users.noreply.github.com>
Date: Thu, 13 Oct 2022 12:11:37 +0200
Subject: [PATCH 4/8] Fixed bug in examples for pick and tryPick (#14080)

Co-authored-by: Kevin Ransom (msft) <codecutter@hotmail.com>
---
 src/FSharp.Core/list.fsi | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/FSharp.Core/list.fsi b/src/FSharp.Core/list.fsi
index db6a16c2bcb..782a035e891 100644
--- a/src/FSharp.Core/list.fsi
+++ b/src/FSharp.Core/list.fsi
@@ -1674,7 +1674,7 @@ module List =
     /// <code lang="fsharp">
     /// let input = [1; 2; 3]
     ///
-    /// input |> List.pick (fun n -> if n > 3 = 0 then Some (string n) else None)
+    /// input |> List.pick (fun n -> if n > 3 then Some (string n) else None)
     /// </code>
     /// Throws <c>KeyNotFoundException</c>.
     /// </example>
@@ -2300,7 +2300,7 @@ module List =
     /// <code lang="fsharp">
     /// let input = [1; 2; 3]
     ///
-    /// input |> List.tryPick (fun n -> if n > 3 = 0 then Some (string n) else None)
+    /// input |> List.tryPick (fun n -> if n > 3 then Some (string n) else None)
     /// </code>
     /// Evaluates to <c>None</c>.
     /// </example>

From 80c3d34989a79dbde8fb797ac32a5a465d33ee51 Mon Sep 17 00:00:00 2001
From: Edgar Gonzalez <edgar.gonzalez@fundourselves.com>
Date: Thu, 13 Oct 2022 13:08:14 +0200
Subject: [PATCH 5/8] Compiler error for signature/implementation files when
 declaring multiple parameters with the same name in abstract methods (#14084)

---
 src/Compiler/Checking/CheckDeclarations.fs    |  31 +++-
 src/Compiler/FSComp.txt                       |   3 +-
 src/Compiler/xlf/FSComp.txt.cs.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.de.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.es.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.fr.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.it.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.ja.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.ko.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.pl.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.pt-BR.xlf         |   5 +
 src/Compiler/xlf/FSComp.txt.ru.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.tr.xlf            |   5 +
 src/Compiler/xlf/FSComp.txt.zh-Hans.xlf       |   5 +
 src/Compiler/xlf/FSComp.txt.zh-Hant.xlf       |   5 +
 .../MethodsAndProperties.fs                   | 159 ++++++++++++++++++
 16 files changed, 254 insertions(+), 4 deletions(-)

diff --git a/src/Compiler/Checking/CheckDeclarations.fs b/src/Compiler/Checking/CheckDeclarations.fs
index ac0080ca829..3bb776b2399 100644
--- a/src/Compiler/Checking/CheckDeclarations.fs
+++ b/src/Compiler/Checking/CheckDeclarations.fs
@@ -395,7 +395,22 @@ let CheckDuplicates (idf: _ -> Ident) k elems =
                 errorR (Duplicate(k, id1.idText, id1.idRange))))
     elems
 
-
+let private CheckDuplicatesArgNames (synVal: SynValSig) m =
+    let argNames = synVal.SynInfo.ArgNames |> List.duplicates
+    for name in argNames do
+        errorR(Error((FSComp.SR.chkDuplicatedMethodParameter(name), m)))
+
+let private CheckDuplicatesAbstractMethodParmsSig (typeSpecs:  SynTypeDefnSig list) =
+    for SynTypeDefnSig(typeRepr= trepr) in typeSpecs do 
+        match trepr with 
+        | SynTypeDefnSigRepr.ObjectModel(_, synMemberSigs, _) ->
+         for sms in synMemberSigs do
+             match sms with
+             | SynMemberSig.Member(synValSig, _, m) ->
+                CheckDuplicatesArgNames synValSig m
+             | _ -> ()
+        | _ -> ()
+        
 module TcRecdUnionAndEnumDeclarations =
 
     let CombineReprAccess parent vis = 
@@ -3946,6 +3961,14 @@ module TcDeclarations =
              | SynMemberDefn.NestedType (range=m) :: _ -> errorR(Error(FSComp.SR.tcTypesCannotContainNestedTypes(), m))
              | _ -> ()
         | ds ->
+             // Check for duplicated parameters in abstract methods
+            for slot in ds do
+                if isAbstractSlot slot then
+                    match slot with
+                    | SynMemberDefn.AbstractSlot (synVal, _, m) ->
+                        CheckDuplicatesArgNames synVal m
+                    | _ -> ()
+                    
             // Classic class construction 
             let _, ds = List.takeUntil (allFalse [isMember;isAbstractSlot;isInterface;isInherit;isField;isTycon]) ds
             match ds with
@@ -4351,7 +4374,8 @@ let rec TcSignatureElementNonMutRec (cenv: cenv) parent typeNames endm (env: TcE
             let _, _, _, env = TcExceptionDeclarations.TcExnSignature cenv env parent emptyUnscopedTyparEnv (edef, scopem)
             return env
 
-        | SynModuleSigDecl.Types (typeSpecs, m) -> 
+        | SynModuleSigDecl.Types (typeSpecs, m) ->
+            CheckDuplicatesAbstractMethodParmsSig typeSpecs
             let scopem = unionRanges m endm
             let mutRecDefns = typeSpecs |> List.map MutRecShape.Tycon
             let env = TcDeclarations.TcMutRecSignatureDecls cenv env parent typeNames emptyUnscopedTyparEnv m scopem None mutRecDefns
@@ -4521,7 +4545,8 @@ and TcSignatureElementsMutRec cenv parent typeNames m mutRecNSInfo envInitial (d
           let rec loop isNamespace moduleRange defs: MutRecSigsInitialData = 
             ((true, true), defs) ||> List.collectFold (fun (openOk, moduleAbbrevOk) def -> 
                 match def with 
-                | SynModuleSigDecl.Types (typeSpecs, _) -> 
+                | SynModuleSigDecl.Types (typeSpecs, _) ->
+                    CheckDuplicatesAbstractMethodParmsSig typeSpecs
                     let decls = typeSpecs |> List.map MutRecShape.Tycon
                     decls, (false, false)
 
diff --git a/src/Compiler/FSComp.txt b/src/Compiler/FSComp.txt
index 2e3267b01a7..f79a7068cf6 100644
--- a/src/Compiler/FSComp.txt
+++ b/src/Compiler/FSComp.txt
@@ -1656,4 +1656,5 @@ reprStateMachineInvalidForm,"The state machine has an unexpected form"
 3546,parsExpectingPatternInTuple,"Expecting pattern"
 3547,parsExpectedPatternAfterToken,"Expected a pattern after this point"
 3548,matchNotAllowedForUnionCaseWithNoData,"Pattern discard is not allowed for union case that takes no data."
-3549,tcSynTypeOrInvalidInDeclaration,"SynType.Or is not permitted in this declaration"
\ No newline at end of file
+3549,tcSynTypeOrInvalidInDeclaration,"SynType.Or is not permitted in this declaration"
+3550,chkDuplicatedMethodParameter,"Duplicate parameter. The parameter '%s' has been used more that once in this method."
diff --git a/src/Compiler/xlf/FSComp.txt.cs.xlf b/src/Compiler/xlf/FSComp.txt.cs.xlf
index 1489085bcb7..9ecac5b6c31 100644
--- a/src/Compiler/xlf/FSComp.txt.cs.xlf
+++ b/src/Compiler/xlf/FSComp.txt.cs.xlf
@@ -12,6 +12,11 @@
         <target state="translated">Soubor {0} má nerozpoznanou příponu. Zdrojové soubory musí mít příponu .fs, .fsi, .fsx nebo .fsscript.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDuplicatedMethodParameter">
+        <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
+        <target state="new">Duplicate parameter. The parameter '{0}' has been used more that once in this method.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkFeatureNotLanguageSupported">
         <source>Feature '{0}' is not available in F# {1}. Please use language version {2} or greater.</source>
         <target state="translated">Funkce {0} není v jazyce F# {1} dostupná. Použijte prosím jazyk verze {2} nebo vyšší.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.de.xlf b/src/Compiler/xlf/FSComp.txt.de.xlf
index 00da1cbd6af..4f7c728edf8 100644
--- a/src/Compiler/xlf/FSComp.txt.de.xlf
+++ b/src/Compiler/xlf/FSComp.txt.de.xlf
@@ -12,6 +12,11 @@
         <target state="translated">Die Dateierweiterung von „{0}“ wurde nicht erkannt. Quelldateien müssen die Erweiterung .fs, .fsi, .fsx oder .fsscript haben</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDuplicatedMethodParameter">
+        <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
+        <target state="new">Duplicate parameter. The parameter '{0}' has been used more that once in this method.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkFeatureNotLanguageSupported">
         <source>Feature '{0}' is not available in F# {1}. Please use language version {2} or greater.</source>
         <target state="translated">Das Feature "{0}" ist in F# {1} nicht verfügbar. Verwenden Sie Sprachversion {2} oder höher.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.es.xlf b/src/Compiler/xlf/FSComp.txt.es.xlf
index f6cdcdddad2..e57459c4a2b 100644
--- a/src/Compiler/xlf/FSComp.txt.es.xlf
+++ b/src/Compiler/xlf/FSComp.txt.es.xlf
@@ -12,6 +12,11 @@
         <target state="translated">No se reconoce la extensión de archivo de '{0}'. Los archivos de código fuente deben tener las extensiones .fs, .fsi, .fsx o .fsscript</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDuplicatedMethodParameter">
+        <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
+        <target state="new">Duplicate parameter. The parameter '{0}' has been used more that once in this method.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkFeatureNotLanguageSupported">
         <source>Feature '{0}' is not available in F# {1}. Please use language version {2} or greater.</source>
         <target state="translated">La característica "{0}" no está disponible en F# {1}. Use la versión {2} del lenguaje o una posterior.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.fr.xlf b/src/Compiler/xlf/FSComp.txt.fr.xlf
index ec74d45bf45..b93761c594a 100644
--- a/src/Compiler/xlf/FSComp.txt.fr.xlf
+++ b/src/Compiler/xlf/FSComp.txt.fr.xlf
@@ -12,6 +12,11 @@
         <target state="translated">L'extension de fichier de '{0}' n'est pas reconnue. Les fichiers sources doivent avoir l'extension .fs, .fsi, .fsx, ou .fsscript.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDuplicatedMethodParameter">
+        <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
+        <target state="new">Duplicate parameter. The parameter '{0}' has been used more that once in this method.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkFeatureNotLanguageSupported">
         <source>Feature '{0}' is not available in F# {1}. Please use language version {2} or greater.</source>
         <target state="translated">La fonctionnalité '{0}' n'est pas disponible en F# {1}. Utilisez la version de langage {2} ou une version ultérieure.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.it.xlf b/src/Compiler/xlf/FSComp.txt.it.xlf
index 4a810e60fcc..1801e06c6f6 100644
--- a/src/Compiler/xlf/FSComp.txt.it.xlf
+++ b/src/Compiler/xlf/FSComp.txt.it.xlf
@@ -12,6 +12,11 @@
         <target state="translated">Estensione di file di '{0}' non riconosciuta. I file di origine devono avere estensione .fs, .fsi, .fsx or .fsscript</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDuplicatedMethodParameter">
+        <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
+        <target state="new">Duplicate parameter. The parameter '{0}' has been used more that once in this method.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkFeatureNotLanguageSupported">
         <source>Feature '{0}' is not available in F# {1}. Please use language version {2} or greater.</source>
         <target state="translated">La funzionalità '{0}' non è disponibile in F# {1}. Usare la versione {2} o versioni successive del linguaggio.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.ja.xlf b/src/Compiler/xlf/FSComp.txt.ja.xlf
index 0fc08e21cfe..b3d3c99155b 100644
--- a/src/Compiler/xlf/FSComp.txt.ja.xlf
+++ b/src/Compiler/xlf/FSComp.txt.ja.xlf
@@ -12,6 +12,11 @@
         <target state="translated">'{0}' のファイル拡張子は認識されません。ソース ファイルの拡張子は .fs、.fsi、.fsx、または .fsscript にする必要があります。</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDuplicatedMethodParameter">
+        <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
+        <target state="new">Duplicate parameter. The parameter '{0}' has been used more that once in this method.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkFeatureNotLanguageSupported">
         <source>Feature '{0}' is not available in F# {1}. Please use language version {2} or greater.</source>
         <target state="translated">機能 '{0}' は F# {1} では使用できません。{2} 以上の言語バージョンをお使いください。</target>
diff --git a/src/Compiler/xlf/FSComp.txt.ko.xlf b/src/Compiler/xlf/FSComp.txt.ko.xlf
index 9a5deaa0421..cfa2326e06a 100644
--- a/src/Compiler/xlf/FSComp.txt.ko.xlf
+++ b/src/Compiler/xlf/FSComp.txt.ko.xlf
@@ -12,6 +12,11 @@
         <target state="translated">'{0}'의 파일 확장명을 인식할 수 없습니다. 원본 파일의 확장명은 .fs, .fsi, .fsx 또는 .fsscript여야 합니다.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDuplicatedMethodParameter">
+        <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
+        <target state="new">Duplicate parameter. The parameter '{0}' has been used more that once in this method.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkFeatureNotLanguageSupported">
         <source>Feature '{0}' is not available in F# {1}. Please use language version {2} or greater.</source>
         <target state="translated">'{0}' 기능은 F# {1}에서 사용할 수 없습니다. {2} 이상의 언어 버전을 사용하세요.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.pl.xlf b/src/Compiler/xlf/FSComp.txt.pl.xlf
index 7f869a057f2..b530606c2b9 100644
--- a/src/Compiler/xlf/FSComp.txt.pl.xlf
+++ b/src/Compiler/xlf/FSComp.txt.pl.xlf
@@ -12,6 +12,11 @@
         <target state="translated">Rozszerzenie pliku "{0}" nie zostało rozpoznane. Pliki źródłowe muszą mieć rozszerzenie .fs, .fsi, .fsx lub .fsscript</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDuplicatedMethodParameter">
+        <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
+        <target state="new">Duplicate parameter. The parameter '{0}' has been used more that once in this method.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkFeatureNotLanguageSupported">
         <source>Feature '{0}' is not available in F# {1}. Please use language version {2} or greater.</source>
         <target state="translated">Funkcja „{0}” nie jest dostępna w języku F# {1}. Użyj języka w wersji {2} lub nowszej.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.pt-BR.xlf b/src/Compiler/xlf/FSComp.txt.pt-BR.xlf
index 165404290f0..f7379662f5a 100644
--- a/src/Compiler/xlf/FSComp.txt.pt-BR.xlf
+++ b/src/Compiler/xlf/FSComp.txt.pt-BR.xlf
@@ -12,6 +12,11 @@
         <target state="translated">A extensão do arquivo de '{0}' não foi reconhecida. Os arquivos de origem devem ter a extensão .fs, .fsi, .fsx or .fsscript</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDuplicatedMethodParameter">
+        <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
+        <target state="new">Duplicate parameter. The parameter '{0}' has been used more that once in this method.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkFeatureNotLanguageSupported">
         <source>Feature '{0}' is not available in F# {1}. Please use language version {2} or greater.</source>
         <target state="translated">O recurso '{0}' não está disponível no F# {1}. Use a versão da linguagem {2} ou superior.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.ru.xlf b/src/Compiler/xlf/FSComp.txt.ru.xlf
index 52876a45a7d..f0d9472c167 100644
--- a/src/Compiler/xlf/FSComp.txt.ru.xlf
+++ b/src/Compiler/xlf/FSComp.txt.ru.xlf
@@ -12,6 +12,11 @@
         <target state="translated">Расширение файла "{0}" не распознано. Исходные файлы должны иметь расширения FS, FSI, FSX или FSSCRIPT</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDuplicatedMethodParameter">
+        <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
+        <target state="new">Duplicate parameter. The parameter '{0}' has been used more that once in this method.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkFeatureNotLanguageSupported">
         <source>Feature '{0}' is not available in F# {1}. Please use language version {2} or greater.</source>
         <target state="translated">Компонент "{0}" недоступен в F# {1}. Используйте версию языка {2} или выше.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.tr.xlf b/src/Compiler/xlf/FSComp.txt.tr.xlf
index 1c7303bf2fb..4cbfd16f9fa 100644
--- a/src/Compiler/xlf/FSComp.txt.tr.xlf
+++ b/src/Compiler/xlf/FSComp.txt.tr.xlf
@@ -12,6 +12,11 @@
         <target state="translated">'{0}' kaynak dosyasının dosya uzantısı tanınmadı. Kaynak dosyaların uzantısı .fs, .fsi, .fsx veya .fsscript olmalıdır.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDuplicatedMethodParameter">
+        <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
+        <target state="new">Duplicate parameter. The parameter '{0}' has been used more that once in this method.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkFeatureNotLanguageSupported">
         <source>Feature '{0}' is not available in F# {1}. Please use language version {2} or greater.</source>
         <target state="translated">'{0}' özelliği F# {1} sürümünde kullanılamıyor. Lütfen {2} veya daha yüksek bir dil sürümünü kullanın.</target>
diff --git a/src/Compiler/xlf/FSComp.txt.zh-Hans.xlf b/src/Compiler/xlf/FSComp.txt.zh-Hans.xlf
index 45189c5d7dd..499dbad9df2 100644
--- a/src/Compiler/xlf/FSComp.txt.zh-Hans.xlf
+++ b/src/Compiler/xlf/FSComp.txt.zh-Hans.xlf
@@ -12,6 +12,11 @@
         <target state="translated">无法识别“{0}”的文件扩展名。源文件必须具有扩展名 .fs、.fsi、.fsx 或 .fsscript</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDuplicatedMethodParameter">
+        <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
+        <target state="new">Duplicate parameter. The parameter '{0}' has been used more that once in this method.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkFeatureNotLanguageSupported">
         <source>Feature '{0}' is not available in F# {1}. Please use language version {2} or greater.</source>
         <target state="translated">功能“{0}”在 F# {1} 中不可用。请使用 {2} 或更高的语言版本。</target>
diff --git a/src/Compiler/xlf/FSComp.txt.zh-Hant.xlf b/src/Compiler/xlf/FSComp.txt.zh-Hant.xlf
index 27040f48efe..aba607cb582 100644
--- a/src/Compiler/xlf/FSComp.txt.zh-Hant.xlf
+++ b/src/Compiler/xlf/FSComp.txt.zh-Hant.xlf
@@ -12,6 +12,11 @@
         <target state="translated">無法辨識 '{0}' 的副檔名。來源檔案的副檔名必須是 .fs、.fsi、.fsx 或 .fsscript。</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDuplicatedMethodParameter">
+        <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
+        <target state="new">Duplicate parameter. The parameter '{0}' has been used more that once in this method.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkFeatureNotLanguageSupported">
         <source>Feature '{0}' is not available in F# {1}. Please use language version {2} or greater.</source>
         <target state="translated">F# {1} 中無法使用 '{0}' 功能。請使用語言版本 {2} 或更新的版本。</target>
diff --git a/tests/FSharp.Compiler.ComponentTests/Conformance/DeclarationElements/MemberDefinitions/MethodsAndProperties/MethodsAndProperties.fs b/tests/FSharp.Compiler.ComponentTests/Conformance/DeclarationElements/MemberDefinitions/MethodsAndProperties/MethodsAndProperties.fs
index 363e045f26a..fee65b3ad49 100644
--- a/tests/FSharp.Compiler.ComponentTests/Conformance/DeclarationElements/MemberDefinitions/MethodsAndProperties/MethodsAndProperties.fs
+++ b/tests/FSharp.Compiler.ComponentTests/Conformance/DeclarationElements/MemberDefinitions/MethodsAndProperties/MethodsAndProperties.fs
@@ -414,4 +414,163 @@ module MethodsAndProperties =
         |> verifyCompileAndRun
         |> shouldSucceed
 
+    [<Fact>]
+    let ``Error in implementation file with abstract methods when reusing parameters`` () =
+            Fsx """
+namespace Foo
+type I =
+    // Tupled.
+    abstract M : i:int * i:int -> int
+    // Curried.
+    abstract N : i:int -> i:int -> int
+    // More than two.
+    abstract O : i:int * i: int * i:int -> int
+    // Multiple distinct names repeated.
+    abstract P : i:int * j:int * i:int * j:int -> int
+            """
+            |> compile
+            |> shouldFail
+            |> withDiagnostics [
+            (Error 3550, Line 5, Col 5, Line 5, Col 38, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 7, Col 5, Line 7, Col 39, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 9, Col 5, Line 9, Col 47, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 11, Col 5, Line 11, Col 54, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 11, Col 5, Line 11, Col 54, "Duplicate parameter. The parameter 'j' has been used more that once in this method.")
+        ]
+        
+    [<Fact>]
+    let ``Error in signature file with no implementation file with abstract methods when reusing parameters`` () =
+        let encodeFsi =
+            Fsi """
+namespace Foo
+type I =
+    // Tupled.
+    abstract M : i:int * i:int -> int
+    // Curried.
+    abstract N : i:int -> i:int -> int
+    // More than two.
+    abstract O : i:int * i: int * i:int -> int
+    // Multiple distinct names repeated.
+    abstract P : i:int * j:int * i:int * j:int -> int
+    """
+        encodeFsi
+        |> verifyCompile
+        |> shouldFail
+        |> withDiagnostics [
+            (Error 3550, Line 5, Col 5, Line 5, Col 38, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 7, Col 5, Line 7, Col 39, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 9, Col 5, Line 9, Col 47, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 11, Col 5, Line 11, Col 54, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 11, Col 5, Line 11, Col 54, "Duplicate parameter. The parameter 'j' has been used more that once in this method.")
+            (Error 240, Line 2, Col 1, Line 11, Col 54, "The signature file 'Test' does not have a corresponding implementation file. If an implementation file exists then check the 'module' and 'namespace' declarations in the signature and implementation files match.")
+        ]
+
+    [<Fact>]
+    let ``Error in signature file with not implementation file with abstract methods when reusing parameters in recursive namespace`` () =
+        let encodeFsi =
+            Fsi """
+namespace rec Foo
+type I =
+    // Tupled.
+    abstract M : i:int * i:int -> int
+    // Curried.
+    abstract N : i:int -> i:int -> int
+    // More than two.
+    abstract O : i:int * i: int * i:int -> int
+    // Multiple distinct names repeated.
+    abstract P : i:int * j:int * i:int * j:int -> int
+    """
+        encodeFsi
+        |> verifyCompile
+        |> shouldFail
+        |> withDiagnostics [
+            (Error 3550, Line 5, Col 5, Line 5, Col 38, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 7, Col 5, Line 7, Col 39, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 9, Col 5, Line 9, Col 47, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 11, Col 5, Line 11, Col 54, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 11, Col 5, Line 11, Col 54, "Duplicate parameter. The parameter 'j' has been used more that once in this method.")
+            (Error 240, Line 2, Col 1, Line 11, Col 54, "The signature file 'Test' does not have a corresponding implementation file. If an implementation file exists then check the 'module' and 'namespace' declarations in the signature and implementation files match.")
+        ]
+
+    [<Fact>]
+    let ``Errors in signature and implementation files with abstract methods when reusing parameters`` () =
+        let encodeFsi =
+            Fsi """
+namespace Foo
+type I =
+    // Tupled.
+    abstract M : i:int * i:int -> int
+    // Curried.
+    abstract N : i:int -> i:int -> int
+    // More than two.
+    abstract O : i:int * i: int * i:int -> int
+    // Multiple distinct names repeated.
+    abstract P : i:int * j:int * i:int * j:int -> int
+    """
+        let encodeFs =
+            FsSource """
+namespace Foo
+type I =
+    abstract M : i:int * i:int -> int
+    abstract N : i:int -> i:int -> int
+    abstract O : i:int * i: int * i:int -> int
+    abstract P : i:int * j:int * i:int * j:int -> int
+        """
+        encodeFsi
+        |> withAdditionalSourceFile encodeFs
+        |> compile
+        |> shouldFail
+        |> withDiagnostics [
+            (Error 3550, Line 5, Col 5, Line 5, Col 38, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 7, Col 5, Line 7, Col 39, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 9, Col 5, Line 9, Col 47, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 11, Col 5, Line 11, Col 54, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 11, Col 5, Line 11, Col 54, "Duplicate parameter. The parameter 'j' has been used more that once in this method.")
+            (Error 3550, Line 4, Col 5, Line 4, Col 38, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 5, Col 5, Line 5, Col 39, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 6, Col 5, Line 6, Col 47, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 7, Col 5, Line 7, Col 54, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 7, Col 5, Line 7, Col 54, "Duplicate parameter. The parameter 'j' has been used more that once in this method.")
+        ]
+
+    [<Fact>]
+    let ``Errors in signature and implementation files with abstract methods when reusing parameters in recursive namespaces`` () =
+        let encodeFsi =
+            Fsi """
+namespace rec Foo
+type I =
+    // Tupled.
+    abstract M : i:int * i:int -> int
+    // Curried.
+    abstract N : i:int -> i:int -> int
+    // More than two.
+    abstract O : i:int * i: int * i:int -> int
+    // Multiple distinct names repeated.
+    abstract P : i:int * j:int * i:int * j:int -> int
+    """
+        let encodeFs =
+            FsSource """
+namespace rec Foo
+type I =
+    abstract M : i:int * i:int -> int
+    abstract N : i:int -> i:int -> int
+    abstract O : i:int * i: int * i:int -> int
+    abstract P : i:int * j:int * i:int * j:int -> int
+        """
+        encodeFsi
+        |> withAdditionalSourceFile encodeFs
+        |> compile
+        |> shouldFail
+        |> withDiagnostics [
+            (Error 3550, Line 5, Col 5, Line 5, Col 38, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 7, Col 5, Line 7, Col 39, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 9, Col 5, Line 9, Col 47, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 11, Col 5, Line 11, Col 54, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 11, Col 5, Line 11, Col 54, "Duplicate parameter. The parameter 'j' has been used more that once in this method.")
+            (Error 3550, Line 4, Col 5, Line 4, Col 38, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 5, Col 5, Line 5, Col 39, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 6, Col 5, Line 6, Col 47, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 7, Col 5, Line 7, Col 54, "Duplicate parameter. The parameter 'i' has been used more that once in this method.")
+            (Error 3550, Line 7, Col 5, Line 7, Col 54, "Duplicate parameter. The parameter 'j' has been used more that once in this method.")
+        ]
 

From 05201993cfaac663c72b6431d81f543e3d001dfe Mon Sep 17 00:00:00 2001
From: Florian Verdonck <florian.verdonck@outlook.com>
Date: Thu, 13 Oct 2022 15:47:45 +0200
Subject: [PATCH 6/8] Leading keyword synbinding (#14056)

* Add SynLeadingKeyword

* Add StaticLet and StaticLetRec.

* Add Do and StaticDo.

* Trigger CI

* Format SyntaxTrivia.

* Update Surface area.

* Trigger CI

Co-authored-by: Tomas Grosup <tomasgrosup@microsoft.com>
---
 .../Checking/AugmentWithHashCompare.fs        |   7 +-
 src/Compiler/Checking/CheckDeclarations.fs    |  20 +-
 src/Compiler/Checking/CheckExpressions.fs     |   4 +-
 .../Checking/CheckIncrementalClasses.fs       |   9 +-
 .../Service/ServiceInterfaceStubGenerator.fs  |   2 +-
 src/Compiler/Service/ServiceNavigation.fs     |  14 +-
 src/Compiler/Service/ServiceParseTreeWalk.fs  |   2 +-
 src/Compiler/Service/ServiceParsedInputOps.fs |   8 +-
 src/Compiler/Service/ServiceStructure.fs      |   4 +-
 src/Compiler/SyntaxTree/ParseHelpers.fs       |  60 +-
 src/Compiler/SyntaxTree/ParseHelpers.fsi      |  17 +-
 src/Compiler/SyntaxTree/SyntaxTree.fs         |  11 +-
 src/Compiler/SyntaxTree/SyntaxTree.fsi        |  12 +-
 src/Compiler/SyntaxTree/SyntaxTreeOps.fs      |  97 +--
 src/Compiler/SyntaxTree/SyntaxTreeOps.fsi     |  31 +-
 src/Compiler/SyntaxTree/SyntaxTrivia.fs       | 103 +++-
 src/Compiler/SyntaxTree/SyntaxTrivia.fsi      |  94 ++-
 src/Compiler/TypedTree/TypedTreePickle.fs     |   4 +-
 src/Compiler/pars.fsy                         | 180 +++---
 .../FSharp.Compiler.Service.Tests.fsproj      |   3 +
 ...erService.SurfaceArea.netstandard.expected | 291 +++++++--
 tests/service/SyntaxTreeTests/BindingTests.fs |   7 +-
 tests/service/SyntaxTreeTests/ExternTests.fs  |   2 +-
 .../SyntaxTreeTests/LeadingKeywordTests.fs    | 561 ++++++++++++++++++
 .../SyntaxTreeTests/MemberFlagTests.fs        |  71 ++-
 tests/service/SyntaxTreeTests/MemberTests.fs  |   6 +-
 .../SyntaxTreeTests/SignatureTypeTests.fs     |   3 +-
 tests/service/TreeVisitorTests.fs             |   2 +-
 28 files changed, 1236 insertions(+), 389 deletions(-)
 create mode 100644 tests/service/SyntaxTreeTests/LeadingKeywordTests.fs

diff --git a/src/Compiler/Checking/AugmentWithHashCompare.fs b/src/Compiler/Checking/AugmentWithHashCompare.fs
index 59d74eb0335..dd81dc0a575 100644
--- a/src/Compiler/Checking/AugmentWithHashCompare.fs
+++ b/src/Compiler/Checking/AugmentWithHashCompare.fs
@@ -7,7 +7,6 @@ open Internal.Utilities.Library
 open FSharp.Compiler.AbstractIL.IL
 open FSharp.Compiler.DiagnosticsLogger
 open FSharp.Compiler.Syntax
-open FSharp.Compiler.SyntaxTrivia
 open FSharp.Compiler.Xml
 open FSharp.Compiler.TcGlobals
 open FSharp.Compiler.TypedTree
@@ -856,8 +855,7 @@ let slotImplMethod (final, c, slotsig) : ValMemberInfo =
           IsFinal=final
           IsOverrideOrExplicitImpl=true
           GetterOrSetterIsCompilerGenerated=false
-          MemberKind=SynMemberKind.Member
-          Trivia=SynMemberFlagsTrivia.Zero}
+          MemberKind=SynMemberKind.Member }
     IsImplemented=false
     ApparentEnclosingEntity=c} 
 
@@ -868,8 +866,7 @@ let nonVirtualMethod c : ValMemberInfo =
                   IsFinal=false
                   IsOverrideOrExplicitImpl=false
                   GetterOrSetterIsCompilerGenerated=false
-                  MemberKind=SynMemberKind.Member
-                  Trivia=SynMemberFlagsTrivia.Zero}
+                  MemberKind=SynMemberKind.Member }
     IsImplemented=false
     ApparentEnclosingEntity=c} 
 
diff --git a/src/Compiler/Checking/CheckDeclarations.fs b/src/Compiler/Checking/CheckDeclarations.fs
index 3bb776b2399..11a372bb5c5 100644
--- a/src/Compiler/Checking/CheckDeclarations.fs
+++ b/src/Compiler/Checking/CheckDeclarations.fs
@@ -452,13 +452,13 @@ module TcRecdUnionAndEnumDeclarations =
         | _ -> ()
         rfspec
 
-    let TcAnonFieldDecl cenv env parent tpenv nm (SynField(Attributes attribs, isStatic, idOpt, ty, isMutable, xmldoc, vis, m)) =
+    let TcAnonFieldDecl cenv env parent tpenv nm (SynField(Attributes attribs, isStatic, idOpt, ty, isMutable, xmldoc, vis, m, _)) =
         let mName = m.MakeSynthetic()
         let id = match idOpt with None -> mkSynId mName nm | Some id -> id
         let xmlDoc = xmldoc.ToXmlDoc(true, Some [])
         TcFieldDecl cenv env parent false tpenv (isStatic, attribs, id, idOpt.IsNone, ty, isMutable, xmlDoc, vis, m)
 
-    let TcNamedFieldDecl cenv env parent isIncrClass tpenv (SynField(Attributes attribs, isStatic, id, ty, isMutable, xmldoc, vis, m)) =
+    let TcNamedFieldDecl cenv env parent isIncrClass tpenv (SynField(Attributes attribs, isStatic, id, ty, isMutable, xmldoc, vis, m, _)) =
         match id with 
         | None -> error (Error(FSComp.SR.tcFieldRequiresName(), m))
         | Some id ->
@@ -494,10 +494,10 @@ module TcRecdUnionAndEnumDeclarations =
             match seen.TryGetValue f.LogicalName with
             | true, synField ->
                 match sf, synField with
-                | SynField(_, _, Some id, _, _, _, _, _), SynField(_, _, Some _, _, _, _, _, _) ->
+                | SynField(idOpt = Some id), SynField(idOpt = Some _) ->
                     error(Error(FSComp.SR.tcFieldNameIsUsedModeThanOnce(id.idText), id.idRange))
-                | SynField(_, _, Some id, _, _, _, _, _), SynField(_, _, None, _, _, _, _, _)
-                | SynField(_, _, None, _, _, _, _, _), SynField(_, _, Some id, _, _, _, _, _) ->
+                | SynField(idOpt = Some id), SynField(idOpt = None)
+                | SynField(idOpt = None), SynField(idOpt = Some id) ->
                     error(Error(FSComp.SR.tcFieldNameConflictsWithGeneratedNameForAnonymousField(id.idText), id.idRange))
                 | _ -> assert false
             | _ ->
@@ -2377,7 +2377,7 @@ module EstablishTypeDefinitionCores =
               for SynUnionCase (caseType=args; range=m) in unionCases do 
                 match args with
                 | SynUnionCaseKind.Fields flds -> 
-                    for SynField(_, _, _, ty, _, _, _, m) in flds do 
+                    for SynField(fieldType = ty; range = m) in flds do 
                         let tyR, _ = TcTypeAndRecover cenv NoNewTypars NoCheckCxs ItemOccurence.UseInType WarnOnIWSAM.Yes env tpenv ty
                         yield (tyR, m)
 
@@ -2394,7 +2394,7 @@ module EstablishTypeDefinitionCores =
 
           | SynTypeDefnSimpleRepr.General (_, _, _, fields, _, _, implicitCtorSynPats, _) when tycon.IsFSharpStructOrEnumTycon -> // for structs
               for field in fields do 
-                  let (SynField(_, isStatic, _, ty, _, _, _, m)) = field
+                  let (SynField(isStatic = isStatic; fieldType = ty; range = m)) = field
                   if not isStatic then 
                       let tyR, _ = TcTypeAndRecover cenv NoNewTypars NoCheckCxs ItemOccurence.UseInType WarnOnIWSAM.Yes env tpenv ty
                       yield (tyR, m)
@@ -2414,7 +2414,7 @@ module EstablishTypeDefinitionCores =
                       yield (ty, m)
 
           | SynTypeDefnSimpleRepr.Record (_, fields, _) -> 
-              for SynField(_, _, _, ty, _, _, _, m) in fields do 
+              for SynField(fieldType = ty; range = m) in fields do 
                   let tyR, _ = TcTypeAndRecover cenv NoNewTypars NoCheckCxs ItemOccurence.UseInType WarnOnIWSAM.Yes env tpenv ty
                   yield (tyR, m)
 
@@ -3998,7 +3998,7 @@ module TcDeclarations =
         | SynTypeDefnRepr.ObjectModel(kind, cspec, m) ->
             let cspec = desugarGetSetMembers cspec
             CheckMembersForm cspec
-            let fields = cspec |> List.choose (function SynMemberDefn.ValField (f, _) -> Some f | _ -> None)
+            let fields = cspec |> List.choose (function SynMemberDefn.ValField (fieldInfo = f) -> Some f | _ -> None)
             let implements2 = cspec |> List.choose (function SynMemberDefn.Interface (interfaceType=ty) -> Some(ty, ty.Range) | _ -> None)
             let inherits =
                 cspec |> List.choose (function 
@@ -4056,7 +4056,7 @@ module TcDeclarations =
                 // Convert auto properties to member bindings in the post-list
                 let rec postAutoProps memb =
                     match memb with 
-                    | SynMemberDefn.AutoProperty(attributes=Attributes attribs; isStatic=isStatic; ident=id; typeOpt=tyOpt; propKind=propKind; memberFlags=memberFlags; memberFlagsForSet=memberFlagsForSet; xmlDoc=xmlDoc; accessibility=access; getSetRange=mGetSetOpt) ->
+                    | SynMemberDefn.AutoProperty(attributes=Attributes attribs; isStatic=isStatic; ident=id; typeOpt=tyOpt; propKind=propKind; memberFlags=memberFlags; memberFlagsForSet=memberFlagsForSet; xmlDoc=xmlDoc; accessibility=access; trivia = { GetSetKeyword = mGetSetOpt }) ->
                         let mMemberPortion = id.idRange
                         // Only the keep the non-field-targeted attributes
                         let attribs = attribs |> List.filter (fun a -> match a.Target with Some t when t.idText = "field" -> false | _ -> true)
diff --git a/src/Compiler/Checking/CheckExpressions.fs b/src/Compiler/Checking/CheckExpressions.fs
index a83ef7d669b..9e6524f2627 100644
--- a/src/Compiler/Checking/CheckExpressions.fs
+++ b/src/Compiler/Checking/CheckExpressions.fs
@@ -6705,7 +6705,7 @@ and TcObjectExprBinding (cenv: cenv) (env: TcEnv) implTy tpenv (absSlotInfo, bin
             | SynPat.Named (SynIdent(id,_), _, _, _), None ->
                 let bindingRhs = PushOnePatternToRhs cenv true (mkSynThisPatVar (ident (CompilerGeneratedName "this", id.idRange))) bindingRhs
                 let logicalMethId = id
-                let memberFlags = OverrideMemberFlags SynMemberFlagsTrivia.Zero SynMemberKind.Member
+                let memberFlags = OverrideMemberFlags SynMemberKind.Member
                 bindingRhs, logicalMethId, memberFlags
 
             | SynPat.InstanceMember(thisId, memberId, _, _, _), Some memberFlags ->
@@ -8579,7 +8579,7 @@ and TcImplicitOpItemThen (cenv: cenv) overallTy env id sln tpenv mItem delayed =
 
     let vs, ves = argTys |> List.mapi (fun i ty -> mkCompGenLocal mItem ("arg" + string i) ty) |> List.unzip
 
-    let memberFlags = StaticMemberFlags SynMemberFlagsTrivia.Zero SynMemberKind.Member
+    let memberFlags = StaticMemberFlags SynMemberKind.Member
     let logicalCompiledName = ComputeLogicalName id memberFlags
     let traitInfo = TTrait(argTys, logicalCompiledName, memberFlags, argTys, Some retTy, sln)
 
diff --git a/src/Compiler/Checking/CheckIncrementalClasses.fs b/src/Compiler/Checking/CheckIncrementalClasses.fs
index c58414dfb00..893cdc4e193 100644
--- a/src/Compiler/Checking/CheckIncrementalClasses.fs
+++ b/src/Compiler/Checking/CheckIncrementalClasses.fs
@@ -14,7 +14,6 @@ open FSharp.Compiler.CompilerGlobalState
 open FSharp.Compiler.DiagnosticsLogger
 open FSharp.Compiler.NameResolution
 open FSharp.Compiler.Syntax
-open FSharp.Compiler.SyntaxTrivia
 open FSharp.Compiler.SyntaxTreeOps
 open FSharp.Compiler.Text
 open FSharp.Compiler.Xml
@@ -122,7 +121,7 @@ let TcImplicitCtorLhs_Phase2A(cenv: cenv, env, tpenv, tcref: TyconRef, vis, attr
 
         // NOTE: no attributes can currently be specified for the implicit constructor 
         let attribs = TcAttributes cenv env (AttributeTargets.Constructor ||| AttributeTargets.Method) attrs
-        let memberFlags = CtorMemberFlags SynMemberFlagsTrivia.Zero
+        let memberFlags = CtorMemberFlags
                                   
         let synArgInfos = List.map (SynInfo.InferSynArgInfoFromSimplePat []) spats
         let valSynData = SynValInfo([synArgInfos], SynInfo.unnamedRetVal)
@@ -150,8 +149,8 @@ let TcImplicitCtorLhs_Phase2A(cenv: cenv, env, tpenv, tcref: TyconRef, vis, attr
             let cctorTy = mkFunTy g g.unit_ty g.unit_ty
             let valSynData = SynValInfo([[]], SynInfo.unnamedRetVal)
             let id = ident ("cctor", m)
-            CheckForNonAbstractInterface ModuleOrMemberBinding tcref (ClassCtorMemberFlags SynMemberFlagsTrivia.Zero) id.idRange
-            let memberInfo = MakeMemberDataAndMangledNameForMemberVal(g, tcref, false, [], [], (ClassCtorMemberFlags SynMemberFlagsTrivia.Zero), valSynData, id, false)
+            CheckForNonAbstractInterface ModuleOrMemberBinding tcref ClassCtorMemberFlags id.idRange
+            let memberInfo = MakeMemberDataAndMangledNameForMemberVal(g, tcref, false, [], [], ClassCtorMemberFlags, valSynData, id, false)
             let prelimValReprInfo = TranslateSynValInfo m (TcAttributes cenv env) valSynData
             let prelimTyschemeG = GeneralizedType(copyOfTyconTypars, cctorTy)
             let valReprInfo = InferGenericArityFromTyScheme prelimTyschemeG prelimValReprInfo
@@ -323,7 +322,7 @@ type IncrClassReprInfo =
                 let tps, _, argInfos, _, _ = GetValReprTypeInCompiledForm g valReprInfo 0 v.Type v.Range
 
                 let valSynInfo = SynValInfo(argInfos |> List.mapSquared (fun (_, argInfo) -> SynArgInfo([], false, argInfo.Name)), SynInfo.unnamedRetVal)
-                let memberFlags = (if isStatic then StaticMemberFlags else NonVirtualMemberFlags) SynMemberFlagsTrivia.Zero SynMemberKind.Member
+                let memberFlags = (if isStatic then StaticMemberFlags else NonVirtualMemberFlags) SynMemberKind.Member
                 let id = mkSynId v.Range name
                 let memberInfo = MakeMemberDataAndMangledNameForMemberVal(g, tcref, false, [], [], memberFlags, valSynInfo, mkSynId v.Range name, true)
 
diff --git a/src/Compiler/Service/ServiceInterfaceStubGenerator.fs b/src/Compiler/Service/ServiceInterfaceStubGenerator.fs
index bf28a121d43..a5a3f8d844a 100644
--- a/src/Compiler/Service/ServiceInterfaceStubGenerator.fs
+++ b/src/Compiler/Service/ServiceInterfaceStubGenerator.fs
@@ -841,7 +841,7 @@ module InterfaceStubGenerator =
                     | None, Some binding -> walkBinding binding
                     | Some getBinding, Some setBinding -> walkBinding getBinding |> Option.orElseWith (fun () -> walkBinding setBinding)
                 | SynMemberDefn.NestedType (typeDef, _access, _range) -> walkSynTypeDefn typeDef
-                | SynMemberDefn.ValField (_field, _range) -> None
+                | SynMemberDefn.ValField _ -> None
                 | SynMemberDefn.LetBindings (bindings, _isStatic, _isRec, _range) -> List.tryPick walkBinding bindings
                 | SynMemberDefn.Open _
                 | SynMemberDefn.ImplicitCtor _
diff --git a/src/Compiler/Service/ServiceNavigation.fs b/src/Compiler/Service/ServiceNavigation.fs
index c38ce9793e2..8f5a4acb2b1 100755
--- a/src/Compiler/Service/ServiceNavigation.fs
+++ b/src/Compiler/Service/ServiceNavigation.fs
@@ -118,7 +118,7 @@ module NavigationImpl =
         match fldspec with
         | SynUnionCaseKind.Fields (flds) ->
             flds
-            |> List.fold (fun st (SynField (_, _, _, _, _, _, _, m)) -> unionRangesChecked m st) range.Zero
+            |> List.fold (fun st (SynField (range = m)) -> unionRangesChecked m st) range.Zero
         | SynUnionCaseKind.FullType (ty, _) -> ty.Range
 
     let bodyRange mBody decls =
@@ -292,7 +292,7 @@ module NavigationImpl =
                 | SynTypeDefnSimpleRepr.Record (_, fields, mBody) ->
                     let fields =
                         [
-                            for SynField (_, _, id, _, _, _, _, m) in fields do
+                            for SynField (idOpt = id; range = m) in fields do
                                 match id with
                                 | Some ident -> yield createMember (ident, NavigationItemKind.Field, FSharpGlyph.Field, m, NavigationEntityKind.Record, false, access)
                                 | _ -> ()
@@ -328,7 +328,7 @@ module NavigationImpl =
                      | SynMemberDefn.GetSetMember (Some bind, None, _, _)
                      | SynMemberDefn.GetSetMember (None, Some bind, _, _)
                      | SynMemberDefn.Member (bind, _) -> processBinding true enclosingEntityKind false bind
-                     | SynMemberDefn.ValField (SynField (_, _, Some (rcid), _, _, _, access, range), _) ->
+                     | SynMemberDefn.ValField(fieldInfo = SynField (idOpt = Some rcid; accessibility = access; range = range)) ->
                          [
                              createMember (rcid, NavigationItemKind.Field, FSharpGlyph.Field, range, enclosingEntityKind, false, access)
                          ]
@@ -534,7 +534,7 @@ module NavigationImpl =
                     | SynTypeDefnSimpleRepr.Record (_, fields, mBody) ->
                         let fields =
                             [
-                                for SynField (_, _, id, _, _, _, _, m) in fields do
+                                for SynField (idOpt = id; range = m) in fields do
                                     match id with
                                     | Some ident -> yield createMember (ident, NavigationItemKind.Field, FSharpGlyph.Field, m, NavigationEntityKind.Record, false, access)
                                     | _ -> ()
@@ -559,7 +559,7 @@ module NavigationImpl =
                     match memb with
                     | SynMemberSig.Member (SynValSig.SynValSig (ident = SynIdent (id, _); accessibility = access; range = m), _, _) ->
                         createMember (id, NavigationItemKind.Method, FSharpGlyph.Method, m, NavigationEntityKind.Class, false, access)
-                    | SynMemberSig.ValField (SynField (_, _, Some (rcid), ty, _, _, access, _), _) ->
+                    | SynMemberSig.ValField (SynField (idOpt = Some rcid; fieldType = ty; accessibility = access), _) ->
                         createMember (rcid, NavigationItemKind.Field, FSharpGlyph.Field, ty.Range, NavigationEntityKind.Class, false, access)
                     | _ -> ()
             ]
@@ -767,7 +767,7 @@ module NavigateTo =
             addIdent kind id isSig container
 
         let addField synField isSig container =
-            let (SynField (_, _, id, _, _, _, _, _)) = synField
+            let (SynField (idOpt = id)) = synField
 
             match id with
             | Some id -> addIdent NavigableItemKind.Field id isSig container
@@ -993,7 +993,7 @@ module NavigateTo =
                 Option.iter (fun b -> addBinding b None container) getBinding
                 Option.iter (fun b -> addBinding b None container) setBinding
             | SynMemberDefn.NestedType (typeDef, _, _) -> walkSynTypeDefn typeDef container
-            | SynMemberDefn.ValField (field, _) -> addField field false container
+            | SynMemberDefn.ValField (fieldInfo = field) -> addField field false container
             | SynMemberDefn.LetBindings (bindings, _, _, _) ->
                 bindings
                 |> List.iter (fun binding -> addBinding binding (Some NavigableItemKind.Field) container)
diff --git a/src/Compiler/Service/ServiceParseTreeWalk.fs b/src/Compiler/Service/ServiceParseTreeWalk.fs
index 274d2741365..25e7544fb03 100755
--- a/src/Compiler/Service/ServiceParseTreeWalk.fs
+++ b/src/Compiler/Service/ServiceParseTreeWalk.fs
@@ -941,7 +941,7 @@ module SyntaxTraversal =
                         |> pick x
                 | ok -> ok
             | SynMemberDefn.Inherit (synType, _identOption, range) -> traverseInherit (synType, range)
-            | SynMemberDefn.ValField (_synField, _range) -> None
+            | SynMemberDefn.ValField _ -> None
             | SynMemberDefn.NestedType (synTypeDefn, _synAccessOption, _range) -> traverseSynTypeDefn path synTypeDefn
 
         and traverseSynMatchClause origPath mc =
diff --git a/src/Compiler/Service/ServiceParsedInputOps.fs b/src/Compiler/Service/ServiceParsedInputOps.fs
index 3ff647478a8..7317df67378 100644
--- a/src/Compiler/Service/ServiceParsedInputOps.fs
+++ b/src/Compiler/Service/ServiceParsedInputOps.fs
@@ -857,7 +857,7 @@ module ParsedInput =
             | _ -> None
 
         and walkField synField =
-            let (SynField (Attributes attrs, _, _, t, _, _, _, _)) = synField
+            let (SynField (attributes = Attributes attrs; fieldType = t)) = synField
             List.tryPick walkAttribute attrs |> Option.orElseWith (fun () -> walkType t)
 
         and walkValSig synValSig =
@@ -906,7 +906,7 @@ module ParsedInput =
 
             | SynMemberDefn.Inherit (t, _, _) -> walkType t
 
-            | SynMemberDefn.ValField (field, _) -> walkField field
+            | SynMemberDefn.ValField (fieldInfo = field) -> walkField field
 
             | SynMemberDefn.NestedType (tdef, _, _) -> walkTypeDefn tdef
 
@@ -1853,7 +1853,7 @@ module ParsedInput =
                 walkType t
             | _ -> ()
 
-        and walkField (SynField (Attributes attrs, _, _, t, _, _, _, _)) =
+        and walkField (SynField (attributes = Attributes attrs; fieldType = t)) =
             List.iter walkAttribute attrs
             walkType t
 
@@ -1904,7 +1904,7 @@ module ParsedInput =
                 walkType t
                 members |> Option.iter (List.iter walkMember)
             | SynMemberDefn.Inherit (t, _, _) -> walkType t
-            | SynMemberDefn.ValField (field, _) -> walkField field
+            | SynMemberDefn.ValField (fieldInfo = field) -> walkField field
             | SynMemberDefn.NestedType (tdef, _, _) -> walkTypeDefn tdef
             | SynMemberDefn.AutoProperty (attributes = Attributes attrs; typeOpt = t; synExpr = e) ->
                 List.iter walkAttribute attrs
diff --git a/src/Compiler/Service/ServiceStructure.fs b/src/Compiler/Service/ServiceStructure.fs
index 210f3f4f9e8..5e381130ed8 100644
--- a/src/Compiler/Service/ServiceStructure.fs
+++ b/src/Compiler/Service/ServiceStructure.fs
@@ -639,7 +639,7 @@ module Structure =
             | SynTypeDefnSimpleRepr.Record (_, fields, rr) ->
                 rcheck Scope.RecordDefn Collapse.Same rr rr
 
-                for SynField (attrs, _, _, _, _, _, _, fr) in fields do
+                for SynField (attributes = attrs; range = fr) in fields do
                     rcheck Scope.RecordField Collapse.Below fr fr
                     parseAttributes attrs
 
@@ -893,7 +893,7 @@ module Structure =
             | SynMemberSig.Member (valSigs, _, r) ->
                 let collapse = Range.endToEnd valSigs.RangeOfId r
                 rcheck Scope.Member Collapse.Below r collapse
-            | SynMemberSig.ValField (SynField (attrs, _, _, _, _, _, _, fr), mFull) ->
+            | SynMemberSig.ValField (SynField (attributes = attrs; range = fr), mFull) ->
                 let collapse = Range.endToEnd fr mFull
                 rcheck Scope.Val Collapse.Below mFull collapse
                 parseAttributes attrs
diff --git a/src/Compiler/SyntaxTree/ParseHelpers.fs b/src/Compiler/SyntaxTree/ParseHelpers.fs
index ca0b858a0ba..b97bfe2f7c8 100644
--- a/src/Compiler/SyntaxTree/ParseHelpers.fs
+++ b/src/Compiler/SyntaxTree/ParseHelpers.fs
@@ -428,7 +428,7 @@ let mkSynMemberDefnGetSet
     (propertyNameBindingPat: SynPat)
     (optPropertyType: SynReturnInfo option)
     (visNoLongerUsed: SynAccess option)
-    (memFlagsBuilder: SynMemberKind -> SynMemberFlags)
+    flagsBuilderAndLeadingKeyword
     (attrs: SynAttributeList list)
     (rangeStart: range)
     : SynMemberDefn list =
@@ -436,6 +436,7 @@ let mkSynMemberDefnGetSet
     let mutable hasGet = false
     let mutable hasSet = false
 
+    let memFlagsBuilder, leadingKeyword = flagsBuilderAndLeadingKeyword
     let xmlDoc = grabXmlDocAtRangeStart (parseState, attrs, rangeStart)
 
     let tryMkSynMemberDefnMember
@@ -467,9 +468,8 @@ let mkSynMemberDefnGetSet
 
         let trivia: SynBindingTrivia =
             {
-                LetKeyword = None
+                LeadingKeyword = leadingKeyword
                 EqualsRange = mEquals
-                ExternKeyword = None
             }
 
         let binding =
@@ -540,13 +540,6 @@ let mkSynMemberDefnGetSet
                 | _ -> optReturnType
 
             // REDO with the correct member kind
-            let trivia: SynBindingTrivia =
-                {
-                    LetKeyword = None
-                    EqualsRange = mEquals
-                    ExternKeyword = None
-                }
-
             let binding =
                 mkSynBinding
                     (PreXmlDoc.Empty, bindingPat)
@@ -627,14 +620,6 @@ let mkSynMemberDefnGetSet
             // replacing the get/set identifier. A little gross.
 
             let (bindingPatAdjusted, getOrSetIdentOpt), xmlDocAdjusted =
-
-                let trivia: SynBindingTrivia =
-                    {
-                        LetKeyword = None
-                        EqualsRange = mEquals
-                        ExternKeyword = None
-                    }
-
                 let bindingOuter =
                     mkSynBinding
                         (xmlDoc, propertyNameBindingPat)
@@ -894,7 +879,7 @@ let mkUnderscoreRecdField m =
 let mkRecdField (lidwd: SynLongIdent) = lidwd, true
 
 // Used for 'do expr' in a class.
-let mkSynDoBinding (vis: SynAccess option, expr, m) =
+let mkSynDoBinding (vis: SynAccess option, mDo, expr, m) =
     match vis with
     | Some vis -> errorR (Error(FSComp.SR.parsDoCannotHaveVisibilityDeclarations (vis.ToString()), m))
     | None -> ()
@@ -912,7 +897,10 @@ let mkSynDoBinding (vis: SynAccess option, expr, m) =
         expr,
         m,
         DebugPointAtBinding.NoneAtDo,
-        SynBindingTrivia.Zero
+        {
+            LeadingKeyword = SynLeadingKeyword.Do mDo
+            EqualsRange = None
+        }
     )
 
 let mkSynExprDecl (e: SynExpr) = SynModuleDecl.Expr(e, e.Range)
@@ -997,6 +985,30 @@ let mkClassMemberLocalBindings
     if isUse then
         errorR (Error(FSComp.SR.parsUseBindingsIllegalInImplicitClassConstructors (), mWhole))
 
+    let decls =
+        match initialRangeOpt, decls with
+        | _, [] -> []
+        | Some mStatic, SynBinding (a0, k, il, im, a, x, v, h, ri, e, m, dp, trivia) :: rest ->
+            // prepend static keyword to existing leading keyword.
+            let trivia =
+                match trivia.LeadingKeyword with
+                | SynLeadingKeyword.LetRec (mLet, mRec) ->
+                    { trivia with
+                        LeadingKeyword = SynLeadingKeyword.StaticLetRec(mStatic, mLet, mRec)
+                    }
+                | SynLeadingKeyword.Let mLet ->
+                    { trivia with
+                        LeadingKeyword = SynLeadingKeyword.StaticLet(mStatic, mLet)
+                    }
+                | SynLeadingKeyword.Do mDo ->
+                    { trivia with
+                        LeadingKeyword = SynLeadingKeyword.StaticDo(mStatic, mDo)
+                    }
+                | _ -> trivia
+
+            SynBinding(a0, k, il, im, a, x, v, h, ri, e, m, dp, trivia) :: rest
+        | None, decls -> decls
+
     SynMemberDefn.LetBindings(decls, isStatic, isRec, mWhole)
 
 let mkLocalBindings (mWhole, BindingSetPreAttrs (_, isRec, isUse, declsPreAttrs, _), mIn, body: SynExpr) =
@@ -1056,3 +1068,11 @@ let checkForMultipleAugmentations m a1 a2 =
 let rangeOfLongIdent (lid: LongIdent) =
     System.Diagnostics.Debug.Assert(not lid.IsEmpty, "the parser should never produce a long-id that is the empty list")
     (lid.Head.idRange, lid) ||> unionRangeWithListBy (fun id -> id.idRange)
+
+let appendValToLeadingKeyword mVal leadingKeyword =
+    match leadingKeyword with
+    | SynLeadingKeyword.StaticMember (mStatic, mMember) -> SynLeadingKeyword.StaticMemberVal(mStatic, mMember, mVal)
+    | SynLeadingKeyword.Member mMember -> SynLeadingKeyword.MemberVal(mMember, mVal)
+    | SynLeadingKeyword.Override mOverride -> SynLeadingKeyword.OverrideVal(mOverride, mVal)
+    | SynLeadingKeyword.Default (mDefault) -> SynLeadingKeyword.DefaultVal(mDefault, mVal)
+    | _ -> leadingKeyword
diff --git a/src/Compiler/SyntaxTree/ParseHelpers.fsi b/src/Compiler/SyntaxTree/ParseHelpers.fsi
index b5f9bac57f9..1192608dbfb 100644
--- a/src/Compiler/SyntaxTree/ParseHelpers.fsi
+++ b/src/Compiler/SyntaxTree/ParseHelpers.fsi
@@ -4,6 +4,7 @@ module internal FSharp.Compiler.ParseHelpers
 
 open FSharp.Compiler.AbstractIL.IL
 open FSharp.Compiler.Syntax
+open FSharp.Compiler.SyntaxTrivia
 open FSharp.Compiler.Features
 open FSharp.Compiler.Text
 open FSharp.Compiler.Xml
@@ -84,7 +85,7 @@ module LexbufIfdefStore =
 
     val SaveEndIfHash: lexbuf: UnicodeLexing.Lexbuf * lexed: string * range: range -> unit
 
-    val GetTrivia: lexbuf: UnicodeLexing.Lexbuf -> SyntaxTrivia.ConditionalDirectiveTrivia list
+    val GetTrivia: lexbuf: UnicodeLexing.Lexbuf -> ConditionalDirectiveTrivia list
 
 module LexbufCommentStore =
 
@@ -92,7 +93,7 @@ module LexbufCommentStore =
 
     val SaveBlockComment: lexbuf: UnicodeLexing.Lexbuf * startRange: range * endRange: range -> unit
 
-    val GetComments: lexbuf: UnicodeLexing.Lexbuf -> SyntaxTrivia.CommentTrivia list
+    val GetComments: lexbuf: UnicodeLexing.Lexbuf -> CommentTrivia list
 
     val ClearComments: lexbuf: UnicodeLexing.Lexbuf -> unit
 
@@ -171,10 +172,10 @@ val mkSynMemberDefnGetSet:
     propertyNameBindingPat: SynPat ->
     optPropertyType: SynReturnInfo option ->
     visNoLongerUsed: SynAccess option ->
-    memFlagsBuilder: (SynMemberKind -> SynMemberFlags) ->
-    attrs: SynAttributeList list ->
-    rangeStart: range ->
-        SynMemberDefn list
+    flagsBuilderAndLeadingKeyword: (SynMemberKind -> SynMemberFlags) * SynLeadingKeyword ->
+        attrs: SynAttributeList list ->
+        rangeStart: range ->
+            SynMemberDefn list
 
 /// Incorporate a '^' for an qualified access to a generic type parameter
 val adjustHatPrefixToTyparLookup: mFull: range -> rightExpr: SynExpr -> SynExpr
@@ -201,7 +202,7 @@ val mkUnderscoreRecdField: m: range -> SynLongIdent * bool
 
 val mkRecdField: lidwd: SynLongIdent -> SynLongIdent * bool
 
-val mkSynDoBinding: vis: SynAccess option * expr: SynExpr * m: range -> SynBinding
+val mkSynDoBinding: vis: SynAccess option * mDo: range * expr: SynExpr * m: range -> SynBinding
 
 val mkSynExprDecl: e: SynExpr -> SynModuleDecl
 
@@ -233,3 +234,5 @@ val idOfPat: parseState: IParseState -> m: range -> p: SynPat -> Ident
 val checkForMultipleAugmentations: m: range -> a1: 'a list -> a2: 'a list -> 'a list
 
 val rangeOfLongIdent: lid: LongIdent -> range
+
+val appendValToLeadingKeyword: mVal: range -> leadingKeyword: SynLeadingKeyword -> SynLeadingKeyword
diff --git a/src/Compiler/SyntaxTree/SyntaxTree.fs b/src/Compiler/SyntaxTree/SyntaxTree.fs
index 051bb1e7af8..bdbf10665d0 100644
--- a/src/Compiler/SyntaxTree/SyntaxTree.fs
+++ b/src/Compiler/SyntaxTree/SyntaxTree.fs
@@ -1082,8 +1082,6 @@ type SynMemberFlags =
         GetterOrSetterIsCompilerGenerated: bool
 
         MemberKind: SynMemberKind
-
-        Trivia: SynMemberFlagsTrivia
     }
 
     override this.Equals other =
@@ -1273,7 +1271,8 @@ type SynField =
         isMutable: bool *
         xmlDoc: PreXmlDoc *
         accessibility: SynAccess option *
-        range: range
+        range: range *
+        trivia: SynFieldTrivia
 
 [<NoEquality; NoComparison>]
 type SynComponentInfo =
@@ -1440,11 +1439,9 @@ type SynMemberDefn =
         memberFlagsForSet: SynMemberFlags *
         xmlDoc: PreXmlDoc *
         accessibility: SynAccess option *
-        equalsRange: range *
         synExpr: SynExpr *
-        withKeyword: range option *
-        getSetRange: range option *
-        range: range
+        range: range *
+        trivia: SynMemberDefnAutoPropertyTrivia
 
     member d.Range =
         match d with
diff --git a/src/Compiler/SyntaxTree/SyntaxTree.fsi b/src/Compiler/SyntaxTree/SyntaxTree.fsi
index 4ecffe92ef4..eeee35985e0 100644
--- a/src/Compiler/SyntaxTree/SyntaxTree.fsi
+++ b/src/Compiler/SyntaxTree/SyntaxTree.fsi
@@ -1232,9 +1232,6 @@ type SynMemberFlags =
 
         /// The kind of the member
         MemberKind: SynMemberKind
-
-        /// Additional information
-        Trivia: SynMemberFlagsTrivia
     }
 
 /// Note the member kind is actually computed partially by a syntax tree transformation in tc.fs
@@ -1429,7 +1426,8 @@ type SynField =
         isMutable: bool *
         xmlDoc: PreXmlDoc *
         accessibility: SynAccess option *
-        range: range
+        range: range *
+        trivia: SynFieldTrivia
 
 /// Represents the syntax tree associated with the name of a type definition or module
 /// in signature or implementation.
@@ -1623,11 +1621,9 @@ type SynMemberDefn =
         memberFlagsForSet: SynMemberFlags *
         xmlDoc: PreXmlDoc *
         accessibility: SynAccess option *
-        equalsRange: range *
         synExpr: SynExpr *
-        withKeyword: range option *
-        getSetRange: range option *
-        range: range
+        range: range *
+        trivia: SynMemberDefnAutoPropertyTrivia
 
     /// Gets the syntax range of this construct
     member Range: range
diff --git a/src/Compiler/SyntaxTree/SyntaxTreeOps.fs b/src/Compiler/SyntaxTree/SyntaxTreeOps.fs
index fda76bc0e47..56eb08fee4f 100644
--- a/src/Compiler/SyntaxTree/SyntaxTreeOps.fs
+++ b/src/Compiler/SyntaxTree/SyntaxTreeOps.fs
@@ -172,10 +172,10 @@ let inline unionRangeWithXmlDoc (xmlDoc: PreXmlDoc) range =
         unionRanges xmlDoc.Range range
 
 let mkSynAnonField (ty: SynType, xmlDoc) =
-    SynField([], false, None, ty, false, xmlDoc, None, unionRangeWithXmlDoc xmlDoc ty.Range)
+    SynField([], false, None, ty, false, xmlDoc, None, unionRangeWithXmlDoc xmlDoc ty.Range, SynFieldTrivia.Zero)
 
 let mkSynNamedField (ident, ty: SynType, xmlDoc, m) =
-    SynField([], false, Some ident, ty, false, xmlDoc, None, m)
+    SynField([], false, Some ident, ty, false, xmlDoc, None, m, SynFieldTrivia.Zero)
 
 let mkSynPatVar vis (id: Ident) =
     SynPat.Named(SynIdent(id, None), false, vis, id.idRange)
@@ -690,7 +690,7 @@ let mkSynBinding
     let mBind = unionRangeWithXmlDoc xmlDoc mBind
     SynBinding(vis, SynBindingKind.Normal, isInline, isMutable, attrs, xmlDoc, info, headPat, retTyOpt, rhsExpr, mBind, spBind, trivia)
 
-let NonVirtualMemberFlags trivia k : SynMemberFlags =
+let NonVirtualMemberFlags k : SynMemberFlags =
     {
         MemberKind = k
         IsInstance = true
@@ -698,10 +698,9 @@ let NonVirtualMemberFlags trivia k : SynMemberFlags =
         IsOverrideOrExplicitImpl = false
         IsFinal = false
         GetterOrSetterIsCompilerGenerated = false
-        Trivia = trivia
     }
 
-let CtorMemberFlags trivia : SynMemberFlags =
+let CtorMemberFlags: SynMemberFlags =
     {
         MemberKind = SynMemberKind.Constructor
         IsInstance = false
@@ -709,10 +708,9 @@ let CtorMemberFlags trivia : SynMemberFlags =
         IsOverrideOrExplicitImpl = false
         IsFinal = false
         GetterOrSetterIsCompilerGenerated = false
-        Trivia = trivia
     }
 
-let ClassCtorMemberFlags trivia : SynMemberFlags =
+let ClassCtorMemberFlags: SynMemberFlags =
     {
         MemberKind = SynMemberKind.ClassConstructor
         IsInstance = false
@@ -720,10 +718,9 @@ let ClassCtorMemberFlags trivia : SynMemberFlags =
         IsOverrideOrExplicitImpl = false
         IsFinal = false
         GetterOrSetterIsCompilerGenerated = false
-        Trivia = trivia
     }
 
-let OverrideMemberFlags trivia k : SynMemberFlags =
+let OverrideMemberFlags k : SynMemberFlags =
     {
         MemberKind = k
         IsInstance = true
@@ -731,10 +728,9 @@ let OverrideMemberFlags trivia k : SynMemberFlags =
         IsOverrideOrExplicitImpl = true
         IsFinal = false
         GetterOrSetterIsCompilerGenerated = false
-        Trivia = trivia
     }
 
-let AbstractMemberFlags isInstance trivia k : SynMemberFlags =
+let AbstractMemberFlags isInstance k : SynMemberFlags =
     {
         MemberKind = k
         IsInstance = isInstance
@@ -742,10 +738,9 @@ let AbstractMemberFlags isInstance trivia k : SynMemberFlags =
         IsOverrideOrExplicitImpl = false
         IsFinal = false
         GetterOrSetterIsCompilerGenerated = false
-        Trivia = trivia
     }
 
-let StaticMemberFlags trivia k : SynMemberFlags =
+let StaticMemberFlags k : SynMemberFlags =
     {
         MemberKind = k
         IsInstance = false
@@ -753,10 +748,9 @@ let StaticMemberFlags trivia k : SynMemberFlags =
         IsOverrideOrExplicitImpl = false
         IsFinal = false
         GetterOrSetterIsCompilerGenerated = false
-        Trivia = trivia
     }
 
-let ImplementStaticMemberFlags trivia k : SynMemberFlags =
+let ImplementStaticMemberFlags k : SynMemberFlags =
     {
         MemberKind = k
         IsInstance = false
@@ -764,79 +758,6 @@ let ImplementStaticMemberFlags trivia k : SynMemberFlags =
         IsOverrideOrExplicitImpl = true
         IsFinal = false
         GetterOrSetterIsCompilerGenerated = false
-        Trivia = trivia
-    }
-
-let MemberSynMemberFlagsTrivia (mMember: range) : SynMemberFlagsTrivia =
-    {
-        MemberRange = Some mMember
-        OverrideRange = None
-        AbstractRange = None
-        StaticRange = None
-        DefaultRange = None
-    }
-
-let OverrideSynMemberFlagsTrivia (mOverride: range) : SynMemberFlagsTrivia =
-    {
-        MemberRange = None
-        OverrideRange = Some mOverride
-        AbstractRange = None
-        StaticRange = None
-        DefaultRange = None
-    }
-
-let StaticMemberSynMemberFlagsTrivia (mStatic: range) (mMember: range) : SynMemberFlagsTrivia =
-    {
-        MemberRange = Some mMember
-        OverrideRange = None
-        AbstractRange = None
-        StaticRange = Some mStatic
-        DefaultRange = None
-    }
-
-let DefaultSynMemberFlagsTrivia (mDefault: range) : SynMemberFlagsTrivia =
-    {
-        MemberRange = None
-        OverrideRange = None
-        AbstractRange = None
-        StaticRange = None
-        DefaultRange = Some mDefault
-    }
-
-let AbstractSynMemberFlagsTrivia (mAbstract: range) : SynMemberFlagsTrivia =
-    {
-        MemberRange = None
-        OverrideRange = None
-        AbstractRange = Some mAbstract
-        StaticRange = None
-        DefaultRange = None
-    }
-
-let AbstractMemberSynMemberFlagsTrivia (mAbstract: range) (mMember: range) : SynMemberFlagsTrivia =
-    {
-        MemberRange = Some mMember
-        OverrideRange = None
-        AbstractRange = Some mAbstract
-        StaticRange = None
-        DefaultRange = None
-    }
-
-let StaticAbstractSynMemberFlagsTrivia mStatic mAbstract =
-    {
-        MemberRange = None
-        OverrideRange = None
-        AbstractRange = Some mAbstract
-        StaticRange = Some mStatic
-        DefaultRange = None
-    }
-
-let StaticAbstractMemberSynMemberFlagsTrivia mStatic mAbstract mMember =
-    {
-        MemberRange = Some mMember
-        OverrideRange = None
-        AbstractRange = Some mAbstract
-        StaticRange = Some mStatic
-        DefaultRange = None
     }
 
 let inferredTyparDecls = SynValTyparDecls(None, true)
diff --git a/src/Compiler/SyntaxTree/SyntaxTreeOps.fsi b/src/Compiler/SyntaxTree/SyntaxTreeOps.fsi
index bb72345971e..5c9df2c48d7 100644
--- a/src/Compiler/SyntaxTree/SyntaxTreeOps.fsi
+++ b/src/Compiler/SyntaxTree/SyntaxTreeOps.fsi
@@ -288,36 +288,19 @@ val mkSynBinding:
         trivia: SynBindingTrivia ->
             SynBinding
 
-val NonVirtualMemberFlags: trivia: SynMemberFlagsTrivia -> k: SynMemberKind -> SynMemberFlags
+val NonVirtualMemberFlags: k: SynMemberKind -> SynMemberFlags
 
-val CtorMemberFlags: trivia: SynMemberFlagsTrivia -> SynMemberFlags
+val CtorMemberFlags: SynMemberFlags
 
-val ClassCtorMemberFlags: trivia: SynMemberFlagsTrivia -> SynMemberFlags
+val ClassCtorMemberFlags: SynMemberFlags
 
-val OverrideMemberFlags: trivia: SynMemberFlagsTrivia -> k: SynMemberKind -> SynMemberFlags
+val OverrideMemberFlags: k: SynMemberKind -> SynMemberFlags
 
-val AbstractMemberFlags: isInstance: bool -> trivia: SynMemberFlagsTrivia -> k: SynMemberKind -> SynMemberFlags
+val AbstractMemberFlags: isInstance: bool -> k: SynMemberKind -> SynMemberFlags
 
-val StaticMemberFlags: trivia: SynMemberFlagsTrivia -> k: SynMemberKind -> SynMemberFlags
+val StaticMemberFlags: k: SynMemberKind -> SynMemberFlags
 
-val ImplementStaticMemberFlags: SynMemberFlagsTrivia -> k: SynMemberKind -> SynMemberFlags
-
-val MemberSynMemberFlagsTrivia: mMember: range -> SynMemberFlagsTrivia
-
-val OverrideSynMemberFlagsTrivia: mOverride: range -> SynMemberFlagsTrivia
-
-val StaticMemberSynMemberFlagsTrivia: mStatic: range -> mMember: range -> SynMemberFlagsTrivia
-
-val DefaultSynMemberFlagsTrivia: mDefault: range -> SynMemberFlagsTrivia
-
-val AbstractSynMemberFlagsTrivia: mAbstract: range -> SynMemberFlagsTrivia
-
-val AbstractMemberSynMemberFlagsTrivia: mAbstract: range -> mMember: range -> SynMemberFlagsTrivia
-
-val StaticAbstractSynMemberFlagsTrivia: mStatic: range -> mAbstract: range -> SynMemberFlagsTrivia
-
-val StaticAbstractMemberSynMemberFlagsTrivia:
-    mStatic: range -> mAbstract: range -> mMember: range -> SynMemberFlagsTrivia
+val ImplementStaticMemberFlags: k: SynMemberKind -> SynMemberFlags
 
 val inferredTyparDecls: SynValTyparDecls
 
diff --git a/src/Compiler/SyntaxTree/SyntaxTrivia.fs b/src/Compiler/SyntaxTree/SyntaxTrivia.fs
index 7c15170e74f..5fe77d929a1 100644
--- a/src/Compiler/SyntaxTree/SyntaxTrivia.fs
+++ b/src/Compiler/SyntaxTree/SyntaxTrivia.fs
@@ -155,40 +155,77 @@ type SynTypeDefnSigTrivia =
             WithKeyword = None
         }
 
+[<NoEquality; NoComparison; RequireQualifiedAccess>]
+type SynLeadingKeyword =
+    | Let of letRange: range
+    | LetRec of letRange: range * recRange: range
+    | And of andRange: range
+    | Use of useRange: range
+    | UseRec of useRange: range * recRange: range
+    | Extern of externRange: range
+    | Member of memberRange: range
+    | MemberVal of memberRange: range * valRange: range
+    | Override of overrideRange: range
+    | OverrideVal of overrideRange: range * valRange: range
+    | Abstract of abstractRange: range
+    | AbstractMember of abstractRange: range * memberRange: range
+    | StaticMember of staticRange: range * memberRange: range
+    | StaticMemberVal of staticRange: range * memberRange: range * valRange: range
+    | StaticAbstract of staticRange: range * abstractRange: range
+    | StaticAbstractMember of staticRange: range * abstractMember: range * memberRange: range
+    | StaticVal of staticRange: range * valRange: range
+    | StaticLet of staticRange: range * letRange: range
+    | StaticLetRec of staticRange: range * letRange: range * recRange: range
+    | StaticDo of staticRange: range * doRange: range
+    | Default of defaultRange: range
+    | DefaultVal of defaultRange: range * valRange: range
+    | Val of valRange: range
+    | New of newRange: range
+    | Do of doRange: range
+    | Synthetic
+
+    member this.Range =
+        match this with
+        | Let m
+        | And m
+        | Use m
+        | Extern m
+        | Member m
+        | Override m
+        | Abstract m
+        | Default m
+        | Val m
+        | New m
+        | Do m -> m
+        | LetRec (m1, m2)
+        | UseRec (m1, m2)
+        | AbstractMember (m1, m2)
+        | StaticMember (m1, m2)
+        | StaticAbstract (m1, m2)
+        | StaticAbstractMember (m1, _, m2)
+        | StaticVal (m1, m2)
+        | StaticLet (m1, m2)
+        | StaticLetRec (m1, _, m2)
+        | StaticDo (m1, m2)
+        | DefaultVal (m1, m2)
+        | MemberVal (m1, m2)
+        | OverrideVal (m1, m2)
+        | StaticMemberVal (m1, _, m2) -> Range.unionRanges m1 m2
+        | Synthetic -> Range.Zero
+
 [<NoEquality; NoComparison>]
 type SynBindingTrivia =
     {
-        LetKeyword: range option
-        ExternKeyword: range option
+        LeadingKeyword: SynLeadingKeyword
         EqualsRange: range option
     }
 
     static member Zero: SynBindingTrivia =
         {
-            LetKeyword = None
-            ExternKeyword = None
+            LeadingKeyword = SynLeadingKeyword.Synthetic
             EqualsRange = None
         }
 
-[<NoEquality; NoComparison>]
-type SynMemberFlagsTrivia =
-    {
-        MemberRange: range option
-        OverrideRange: range option
-        AbstractRange: range option
-        StaticRange: range option
-        DefaultRange: range option
-    }
-
-    static member Zero: SynMemberFlagsTrivia =
-        {
-            MemberRange = None
-            OverrideRange = None
-            AbstractRange = None
-            StaticRange = None
-            DefaultRange = None
-        }
-
 [<NoEquality; NoComparison>]
 type SynExprAndBangTrivia =
     {
@@ -239,14 +276,14 @@ type SynModuleOrNamespaceSigTrivia =
 [<NoEquality; NoComparison>]
 type SynValSigTrivia =
     {
-        ValKeyword: range option
+        LeadingKeyword: SynLeadingKeyword
         WithKeyword: range option
         EqualsRange: range option
     }
 
     static member Zero: SynValSigTrivia =
         {
-            ValKeyword = None
+            LeadingKeyword = SynLeadingKeyword.Synthetic
             WithKeyword = None
             EqualsRange = None
         }
@@ -267,4 +304,20 @@ type SynMemberGetSetTrivia =
 type SynArgPatsNamePatPairsTrivia = { ParenRange: range }
 
 [<NoEquality; NoComparison>]
+type SynMemberDefnAutoPropertyTrivia =
+    {
+        LeadingKeyword: SynLeadingKeyword
+        WithKeyword: range option
+        EqualsRange: range option
+        GetSetKeyword: range option
+    }
+
+[<NoEquality; NoComparison>]
+type SynFieldTrivia =
+    {
+        LeadingKeyword: SynLeadingKeyword option
+    }
+
+    static member Zero: SynFieldTrivia = { LeadingKeyword = None }
+
 type SynTypeOrTrivia = { OrKeyword: range }
diff --git a/src/Compiler/SyntaxTree/SyntaxTrivia.fsi b/src/Compiler/SyntaxTree/SyntaxTrivia.fsi
index c52cacea7b2..cae5db553e6 100644
--- a/src/Compiler/SyntaxTree/SyntaxTrivia.fsi
+++ b/src/Compiler/SyntaxTree/SyntaxTrivia.fsi
@@ -239,15 +239,44 @@ type SynTypeDefnSigTrivia =
 
     static member Zero: SynTypeDefnSigTrivia
 
+/// Represents the leading keyword in a SynBinding or SynValSig
+[<NoEquality; NoComparison; RequireQualifiedAccess>]
+type SynLeadingKeyword =
+    | Let of letRange: range
+    | LetRec of letRange: range * recRange: range
+    | And of andRange: range
+    | Use of useRange: range
+    | UseRec of useRange: range * recRange: range
+    | Extern of externRange: range
+    | Member of memberRange: range
+    | MemberVal of memberRange: range * valRange: range
+    | Override of overrideRange: range
+    | OverrideVal of overrideRange: range * valRange: range
+    | Abstract of abstractRange: range
+    | AbstractMember of abstractRange: range * memberRange: range
+    | StaticMember of staticRange: range * memberRange: range
+    | StaticMemberVal of staticRange: range * memberRange: range * valRange: range
+    | StaticAbstract of staticRange: range * abstractRange: range
+    | StaticAbstractMember of staticRange: range * abstractMember: range * memberRange: range
+    | StaticVal of staticRange: range * valRange: range
+    | StaticLet of staticRange: range * letRange: range
+    | StaticLetRec of staticRange: range * letRange: range * recRange: range
+    | StaticDo of staticRange: range * doRange: range
+    | Default of defaultRange: range
+    | DefaultVal of defaultRange: range * valRange: range
+    | Val of valRange: range
+    | New of newRange: range
+    | Do of doRange: range
+    | Synthetic
+
+    member Range: range
+
 /// Represents additional information for SynBinding
 [<NoEquality; NoComparison>]
 type SynBindingTrivia =
     {
-        /// The syntax range of the `let` keyword.
-        LetKeyword: range option
-
-        /// The syntax range of the `extern` keyword.
-        ExternKeyword: range option
+        /// Used leading keyword of SynBinding
+        LeadingKeyword: SynLeadingKeyword
 
         /// The syntax range of the `=` token.
         EqualsRange: range option
@@ -255,28 +284,6 @@ type SynBindingTrivia =
 
     static member Zero: SynBindingTrivia
 
-/// Represents additional information for SynMemberFlags
-[<NoEquality; NoComparison>]
-type SynMemberFlagsTrivia =
-    {
-        /// The syntax range of the `member` keyword
-        MemberRange: range option
-
-        /// The syntax range of the `override` keyword
-        OverrideRange: range option
-
-        /// The syntax range of the `abstract` keyword
-        AbstractRange: range option
-
-        /// The syntax range of the `member` keyword
-        StaticRange: range option
-
-        /// The syntax range of the `default` keyword
-        DefaultRange: range option
-    }
-
-    static member Zero: SynMemberFlagsTrivia
-
 /// Represents additional information for SynExprAndBang
 [<NoEquality; NoComparison>]
 type SynExprAndBangTrivia =
@@ -340,8 +347,10 @@ type SynModuleOrNamespaceSigTrivia =
 [<NoEquality; NoComparison>]
 type SynValSigTrivia =
     {
-        /// The syntax range of the `val` keyword
-        ValKeyword: range option
+        /// Used leading keyword of SynValSig
+        /// In most cases this will be `val`,
+        /// but in case of `SynMemberDefn.AutoProperty` or `SynMemberDefn.AbstractSlot` it could be something else.
+        LeadingKeyword: SynLeadingKeyword
 
         /// The syntax range of the `with` keyword
         WithKeyword: range option
@@ -385,6 +394,33 @@ type SynArgPatsNamePatPairsTrivia =
         ParenRange: range
     }
 
+/// Represents additional information for SynMemberDefn.AutoProperty
+[<NoEquality; NoComparison>]
+type SynMemberDefnAutoPropertyTrivia =
+    {
+        /// Used leading keyword of AutoProperty
+        LeadingKeyword: SynLeadingKeyword
+
+        /// The syntax range of the `with` keyword
+        WithKeyword: range option
+
+        /// The syntax range of the `=` token
+        EqualsRange: range option
+
+        /// The syntax range of 'get, set'
+        GetSetKeyword: range option
+    }
+
+/// Represents additional information for SynField
+[<NoEquality; NoComparison>]
+type SynFieldTrivia =
+    {
+        /// Used leading keyword of SynField
+        LeadingKeyword: SynLeadingKeyword option
+    }
+
+    static member Zero: SynFieldTrivia
+
 /// Represents additional information for SynType.Or
 [<NoEquality; NoComparison>]
 type SynTypeOrTrivia =
diff --git a/src/Compiler/TypedTree/TypedTreePickle.fs b/src/Compiler/TypedTree/TypedTreePickle.fs
index c367865dbc2..90fd15fa1e2 100644
--- a/src/Compiler/TypedTree/TypedTreePickle.fs
+++ b/src/Compiler/TypedTree/TypedTreePickle.fs
@@ -21,7 +21,6 @@ open FSharp.Compiler.DiagnosticsLogger
 open FSharp.Compiler.Text.Position
 open FSharp.Compiler.Text.Range
 open FSharp.Compiler.Syntax
-open FSharp.Compiler.SyntaxTrivia
 open FSharp.Compiler.SyntaxTreeOps
 open FSharp.Compiler.Text
 open FSharp.Compiler.Xml
@@ -1500,8 +1499,7 @@ let u_MemberFlags st : SynMemberFlags=
       IsOverrideOrExplicitImpl=x5
       IsFinal=x6
       GetterOrSetterIsCompilerGenerated=false
-      MemberKind=x7
-      Trivia = SynMemberFlagsTrivia.Zero }
+      MemberKind=x7 }
 
 let fill_u_Expr_hole, u_expr_fwd = u_hole()
 let fill_p_Expr_hole, p_expr_fwd = p_hole()
diff --git a/src/Compiler/pars.fsy b/src/Compiler/pars.fsy
index 1dc110accee..3114c476616 100644
--- a/src/Compiler/pars.fsy
+++ b/src/Compiler/pars.fsy
@@ -702,7 +702,8 @@ valSpfn:
                 | None -> m
                 | Some e -> unionRanges m e.Range
         let mVal = rhs parseState 3
-        let valSpfn = SynValSig((attr1@attr2), id, explicitValTyparDecls, ty, arity, isInline, isMutable, doc, vis2, konst, m, { ValKeyword = Some mVal; WithKeyword = None; EqualsRange = mEquals }) 
+        let trivia: SynValSigTrivia = { LeadingKeyword = SynLeadingKeyword.Val mVal; WithKeyword = None; EqualsRange = mEquals }
+        let valSpfn = SynValSig((attr1@attr2), id, explicitValTyparDecls, ty, arity, isInline, isMutable, doc, vis2, konst, m, trivia) 
         SynModuleSigDecl.Val(valSpfn, m)
       }
 
@@ -832,7 +833,7 @@ tyconSpfnRhs:
   | DELEGATE OF topType
      { let m = lhs parseState 
        let ty, arity = $3
-       let flags = AbstractMemberFlags true SynMemberFlagsTrivia.Zero SynMemberKind.Member
+       let flags = AbstractMemberFlags true SynMemberKind.Member
        let valSig = SynValSig([], (SynIdent(mkSynId m "Invoke", None)), inferredTyparDecls, ty, arity, false, false, PreXmlDoc.Empty, None, None, m, SynValSigTrivia.Zero)
        let invoke = SynMemberSig.Member(valSig, flags, m) 
        (fun nameRange nameInfo mEquals augmentation -> 
@@ -921,9 +922,11 @@ classMemberSpfn:
                match optLiteralValue with
                | None -> m
                | Some e -> unionRanges m e.Range
-       let trivia = { ValKeyword = None; WithKeyword = mWith; EqualsRange = mEquals }
+       
+       let flags, leadingKeyword = $3
+       let flags = flags (getSetAdjuster arity)
+       let trivia = { LeadingKeyword = leadingKeyword; WithKeyword = mWith; EqualsRange = mEquals }
        let valSpfn = SynValSig($1, id, explicitValTyparDecls, ty, arity, isInline, false, doc, vis2, optLiteralValue, mWhole, trivia)
-       let flags = $3 (getSetAdjuster arity)
        SynMemberSig.Member(valSpfn, flags, mWhole) }
 
   | opt_attributes opt_access interfaceMember appType  
@@ -937,14 +940,17 @@ classMemberSpfn:
   | opt_attributes opt_access VAL fieldDecl 
      { let mWhole = rhs2 parseState 1 4
        if Option.isSome $2 then errorR (Error (FSComp.SR.parsVisibilityDeclarationsShouldComePriorToIdentifier (), rhs parseState 2))
-       let (SynField(_, _, _, _, _, xmlDoc, _, _)) as field = $4 $1 false mWhole
+       let mVal = rhs parseState 3
+       let (SynField(xmlDoc = xmlDoc)) as field = $4 $1 false mWhole (Some (SynLeadingKeyword.Val mVal))
        let mWhole = unionRangeWithXmlDoc xmlDoc mWhole
        SynMemberSig.ValField (field, mWhole) }
 
   | opt_attributes opt_access STATIC VAL fieldDecl 
      { let mWhole = rhs2 parseState 1 5
        if Option.isSome $2 then errorR (Error (FSComp.SR.parsVisibilityDeclarationsShouldComePriorToIdentifier (), rhs parseState 2))
-       let (SynField(_, _, _, _, _, xmlDoc, _, _)) as field = $5 $1 true mWhole
+       let mStatic = rhs parseState 3
+       let mVal = rhs parseState 4
+       let (SynField(xmlDoc = xmlDoc)) as field = $5 $1 true mWhole (Some (SynLeadingKeyword.StaticVal(mStatic, mVal)))
        let mWhole = unionRangeWithXmlDoc xmlDoc mWhole
        SynMemberSig.ValField(field, mWhole) }
 
@@ -954,10 +960,12 @@ classMemberSpfn:
 
   | opt_attributes opt_access NEW COLON topTypeWithTypeConstraints  
      { let vis, doc, (ty, valSynInfo) = $2, grabXmlDoc(parseState, $1, 1), $5
+       let mNew = rhs parseState 3
        let m = unionRanges (rhs parseState 1) ty.Range |> unionRangeWithXmlDoc doc
-       let isInline = false 
-       let valSpfn = SynValSig ($1, (SynIdent(mkSynId (rhs parseState 3) "new", None)), noInferredTypars, ty, valSynInfo, isInline, false, doc, vis, None, m, SynValSigTrivia.Zero)
-       SynMemberSig.Member(valSpfn, CtorMemberFlags SynMemberFlagsTrivia.Zero, m) }
+       let isInline = false
+       let trivia: SynValSigTrivia = { LeadingKeyword = SynLeadingKeyword.New mNew; WithKeyword = None; EqualsRange = None }
+       let valSpfn = SynValSig ($1, (SynIdent(mkSynId (rhs parseState 3) "new", None)), noInferredTypars, ty, valSynInfo, isInline, false, doc, vis, None, m, trivia)
+       SynMemberSig.Member(valSpfn, CtorMemberFlags, m) }
 
 
 /* The optional "with get, set" on a member in a signature */
@@ -1438,16 +1446,16 @@ memberFlags:
   | STATIC MEMBER 
       { let mStatic = rhs parseState 1
         let mMember = rhs parseState 2
-        StaticMemberFlags(StaticMemberSynMemberFlagsTrivia mStatic mMember) }  
+        StaticMemberFlags, (SynLeadingKeyword.StaticMember(mStatic, mMember)) }  
   | MEMBER
       { let mMember = rhs parseState 1
-        NonVirtualMemberFlags(MemberSynMemberFlagsTrivia mMember) }
+        NonVirtualMemberFlags, (SynLeadingKeyword.Member mMember) }
   | OVERRIDE
       { let mOverride = rhs parseState 1
-        OverrideMemberFlags(OverrideSynMemberFlagsTrivia mOverride) }
+        OverrideMemberFlags, (SynLeadingKeyword.Override mOverride) }
   | DEFAULT
       { let mDefault = rhs parseState 1
-        OverrideMemberFlags(DefaultSynMemberFlagsTrivia mDefault) }
+        OverrideMemberFlags, (SynLeadingKeyword.Default mDefault) }
 
 /* The name of a type in a signature or implementation, possibly with type parameters and constraints */
 typeNameInfo: 
@@ -1584,7 +1592,7 @@ tyconDefnRhs:
        let ty, arity = $3
        (fun nameRange augmentation -> 
            let valSig = SynValSig([], (SynIdent(mkSynId m "Invoke", None)), inferredTyparDecls, ty, arity, false, false, PreXmlDoc.Empty, None, None, m, SynValSigTrivia.Zero) 
-           let flags = AbstractMemberFlags true SynMemberFlagsTrivia.Zero SynMemberKind.Member
+           let flags = AbstractMemberFlags true SynMemberKind.Member
            let invoke = SynMemberDefn.AbstractSlot(valSig, flags, m) 
            if not (isNil augmentation) then raiseParseErrorAt m (FSComp.SR.parsAugmentationsIllegalOnDelegateType())
            SynTypeDefnRepr.ObjectModel (SynTypeDefnKind.Delegate (ty, arity), [invoke], m), []) }
@@ -1702,12 +1710,13 @@ memberCore:
        let optReturnType = $3
        let mEquals = rhs parseState 4
        let bindingPat, mBindLhs = $2 
-       (fun vis memFlagsBuilder attrs rangeStart ->
+       (fun vis flagsBuilderAndLeadingKeyword attrs rangeStart ->
             let xmlDoc = grabXmlDocAtRangeStart(parseState, attrs, rangeStart)
-            let memberFlags = Some (memFlagsBuilder SynMemberKind.Member)
+            let memFlagsBuilder, leadingKeyword = flagsBuilderAndLeadingKeyword 
+            let memberFlags = memFlagsBuilder SynMemberKind.Member
             let mWholeBindLhs = (mBindLhs, attrs) ||> unionRangeWithListBy (fun (a: SynAttributeList) -> a.Range)
-            let trivia: SynBindingTrivia = { LetKeyword = None; EqualsRange = Some mEquals; ExternKeyword = None }
-            let binding = mkSynBinding (xmlDoc, bindingPat) (vis, $1, false, mWholeBindLhs, DebugPointAtBinding.NoneAtInvisible, optReturnType, $5, mRhs, [], attrs, memberFlags, trivia)
+            let trivia: SynBindingTrivia = { LeadingKeyword = leadingKeyword; EqualsRange = Some mEquals }
+            let binding = mkSynBinding (xmlDoc, bindingPat) (vis, $1, false, mWholeBindLhs, DebugPointAtBinding.NoneAtInvisible, optReturnType, $5, mRhs, [], attrs, Some memberFlags, trivia)
             let memberRange = unionRanges rangeStart mRhs |> unionRangeWithXmlDoc xmlDoc
             [ SynMemberDefn.Member (binding, memberRange) ]) }
 
@@ -1717,17 +1726,26 @@ memberCore:
        let mWhole = (rhs parseState 2, classDefnMemberGetSetElements) ||> unionRangeWithListBy (fun (_, _, _, _, _, _, m2) -> m2) 
        let propertyNameBindingPat, _ = $2 
        let optPropertyType = $3
-       mkSynMemberDefnGetSet parseState $1 mWith classDefnMemberGetSetElements mAnd mWhole propertyNameBindingPat optPropertyType }
+
+       mkSynMemberDefnGetSet
+           parseState 
+           $1 
+           mWith 
+           classDefnMemberGetSetElements 
+           mAnd 
+           mWhole 
+           propertyNameBindingPat 
+           optPropertyType }
 
 abstractMemberFlags: 
   | ABSTRACT
       { let mAbstract = rhs parseState 1
-        AbstractMemberFlags true (AbstractSynMemberFlagsTrivia mAbstract) }
+        AbstractMemberFlags true, SynLeadingKeyword.Abstract mAbstract }
 
   | ABSTRACT MEMBER
       { let mAbstract = rhs parseState 1
         let mMember = rhs parseState 2
-        AbstractMemberFlags true (AbstractMemberSynMemberFlagsTrivia mAbstract mMember) }
+        AbstractMemberFlags true, SynLeadingKeyword.AbstractMember(mAbstract, mMember) }
 
   | STATIC ABSTRACT
       { let mWhole = rhs2 parseState 1 2
@@ -1736,7 +1754,7 @@ abstractMemberFlags:
             warning(Error(FSComp.SR.tcUsingInterfacesWithStaticAbstractMethods(), mWhole))
         let mStatic = rhs parseState 1
         let mAbstract = rhs parseState 2
-        AbstractMemberFlags false (StaticAbstractSynMemberFlagsTrivia mStatic mAbstract) }
+        AbstractMemberFlags false, SynLeadingKeyword.StaticAbstract(mStatic, mAbstract) }
 
   | STATIC ABSTRACT MEMBER
       { let mWhole = rhs2 parseState 1 2
@@ -1746,7 +1764,7 @@ abstractMemberFlags:
         let mStatic = rhs parseState 1
         let mAbstract = rhs parseState 2
         let mMember = rhs parseState 3
-        AbstractMemberFlags false (StaticAbstractMemberSynMemberFlagsTrivia mStatic mAbstract mMember) }
+        AbstractMemberFlags false, SynLeadingKeyword.StaticAbstractMember(mStatic, mAbstract, mMember) }
 
 /* A member definition */
 classDefnMember:
@@ -1786,9 +1804,11 @@ classDefnMember:
            | Some m2 -> unionRanges m m2
            |> unionRangeWithXmlDoc doc
        if Option.isSome $2 then errorR(Error(FSComp.SR.parsAccessibilityModsIllegalForAbstract(), mWhole))
-       let trivia = { ValKeyword = None; WithKeyword = mWith; EqualsRange = None }
+       let mkFlags, leadingKeyword = $3
+       let trivia = { LeadingKeyword = leadingKeyword; WithKeyword = mWith; EqualsRange = None }
        let valSpfn = SynValSig($1, id, explicitValTyparDecls, ty, arity, isInline, false, doc, None, None, mWhole, trivia)
-       [ SynMemberDefn.AbstractSlot(valSpfn, $3 (getSetAdjuster arity), mWhole) ] }
+       
+       [ SynMemberDefn.AbstractSlot(valSpfn, mkFlags (getSetAdjuster arity), mWhole) ] }
        
   | opt_attributes opt_access inheritsDefn
      {  if not (isNil $1) then errorR(Error(FSComp.SR.parsAttributesIllegalOnInherit(), rhs parseState 1))
@@ -1798,12 +1818,13 @@ classDefnMember:
   | opt_attributes opt_access valDefnDecl opt_ODECLEND
      {  if Option.isSome $2 then errorR(Error(FSComp.SR.parsVisibilityDeclarationsShouldComePriorToIdentifier(), rhs parseState 2))
         let rangeStart = rhs parseState 1
-        $3 rangeStart $1 false }
+        $3 rangeStart $1 None }
         
   | opt_attributes opt_access STATIC valDefnDecl opt_ODECLEND
      {  if Option.isSome $2 then errorR(Error(FSComp.SR.parsVisibilityDeclarationsShouldComePriorToIdentifier(), rhs parseState 2))
+        let mStatic = rhs parseState 3
         let rangeStart = rhs parseState 1
-        $4 rangeStart $1 true  }
+        $4 rangeStart $1 (Some mStatic)  }
 
   | opt_attributes opt_access memberFlags autoPropsDefnDecl opt_ODECLEND
      { let rangeStart = rhs parseState 1 
@@ -1814,16 +1835,17 @@ classDefnMember:
 
   | opt_attributes opt_access NEW  atomicPattern optAsSpec EQUALS typedSequentialExprBlock opt_ODECLEND
      {  let mWholeBindLhs = rhs2 parseState 1 (if Option.isSome $5 then 5 else 4)
+        let mNew = rhs parseState 3
         let xmlDoc = grabXmlDoc(parseState, $1, 1)
         let m = unionRanges mWholeBindLhs $7.Range |> unionRangeWithXmlDoc xmlDoc
         let mEquals = rhs parseState 6
         let expr = $7
-        let valSynData = SynValData (Some (CtorMemberFlags SynMemberFlagsTrivia.Zero), SynValInfo([SynInfo.InferSynArgInfoFromPat $4], SynInfo.unnamedRetVal), $5) 
+        let valSynData = SynValData (Some CtorMemberFlags, SynValInfo([SynInfo.InferSynArgInfoFromPat $4], SynInfo.unnamedRetVal), $5) 
         let vis = $2 
         let declPat = SynPat.LongIdent (SynLongIdent([mkSynId (rhs parseState 3) "new"], [], [None]), None, Some noInferredTypars, SynArgPats.Pats [$4], vis, rhs parseState 3)
         // Check that 'SynPatForConstructorDecl' matches this correctly
         assert (match declPat with SynPatForConstructorDecl _ -> true | _ -> false)
-        let synBindingTrivia: SynBindingTrivia = { LetKeyword = None; EqualsRange = Some mEquals; ExternKeyword = None }
+        let synBindingTrivia: SynBindingTrivia = { LeadingKeyword = SynLeadingKeyword.New mNew; EqualsRange = Some mEquals }
         [ SynMemberDefn.Member(SynBinding (None, SynBindingKind.Normal, false, false, $1, xmlDoc, valSynData, declPat, None, expr, mWholeBindLhs, DebugPointAtBinding.NoneAtInvisible, synBindingTrivia), m) ] }
         
   | opt_attributes opt_access STATIC typeKeyword tyconDefn 
@@ -1834,29 +1856,39 @@ classDefnMember:
 /* A 'val' definition in an object type definition */
 valDefnDecl:
   | VAL opt_mutable opt_access ident COLON  typ 
-     {  let mRhs = rhs2 parseState 4 6
+     {  let mVal = rhs parseState 1
+        let mRhs = rhs2 parseState 4 6
         let mValDecl = rhs2 parseState 1 6
-        (fun rangeStart attribs isStatic ->
+        (fun rangeStart attribs mStaticOpt ->
+            let isStatic = Option.isSome mStaticOpt
             let xmlDoc = grabXmlDocAtRangeStart(parseState, attribs, rangeStart)
             let mValDecl = unionRanges rangeStart mValDecl |> unionRangeWithXmlDoc xmlDoc
-            let fld = SynField(attribs, isStatic, Some $4, $6, $2, xmlDoc, $3, mRhs)
+            let leadingKeyword = 
+                match mStaticOpt with
+                | None -> SynLeadingKeyword.Val mVal
+                | Some mStatic -> SynLeadingKeyword.StaticVal(mStatic, mVal)
+            let fld = SynField(attribs, isStatic, Some $4, $6, $2, xmlDoc, $3, mRhs, { LeadingKeyword = Some leadingKeyword })
             [ SynMemberDefn.ValField(fld, mValDecl) ]) }
 
 
 /* An auto-property definition in an object type definition */
 autoPropsDefnDecl:
   | VAL opt_mutable opt_access ident opt_typ EQUALS typedSequentialExprBlock classMemberSpfnGetSet
-     { let mWith, mGetSetOpt, getSet = $8
+     { let mVal = rhs parseState 1
+       let mWith, mGetSetOpt, getSet = $8
        let mEquals = rhs parseState 6
        if $2 then
            errorR (Error (FSComp.SR.parsMutableOnAutoPropertyShouldBeGetSet (), rhs parseState 3))
        (fun attribs flags rangeStart ->
            let xmlDoc = grabXmlDocAtRangeStart(parseState, attribs, rangeStart)
            let memberRange = unionRanges rangeStart $7.Range |> unionRangeWithXmlDoc xmlDoc
+           let flags, leadingKeyword = flags
+           let leadingKeyword = appendValToLeadingKeyword mVal leadingKeyword
            let memberFlags = flags SynMemberKind.Member
            let memberFlagsForSet = flags SynMemberKind.PropertySet
            let isStatic = not memberFlags.IsInstance
-           [ SynMemberDefn.AutoProperty(attribs, isStatic, $4, $5, getSet, memberFlags, memberFlagsForSet, xmlDoc, $3, mEquals, $7, mWith, mGetSetOpt, memberRange) ]) }
+           let trivia = { LeadingKeyword = leadingKeyword; WithKeyword = mWith; EqualsRange = Some mEquals; GetSetKeyword = mGetSetOpt }
+           [ SynMemberDefn.AutoProperty(attribs, isStatic, $4, $5, getSet, memberFlags, memberFlagsForSet, xmlDoc, $3, $7, memberRange, trivia) ]) }
 
 /* An optional type on an auto-property definition */
 opt_typ:
@@ -2026,13 +2058,13 @@ staticMemberOrMemberOrOverride:
   | STATIC MEMBER
       { let mStatic = rhs parseState 1
         let mMember = rhs parseState 2
-        ImplementStaticMemberFlags(StaticMemberSynMemberFlagsTrivia mStatic mMember) }  
+        ImplementStaticMemberFlags, (SynLeadingKeyword.StaticMember(mStatic, mMember)) }  
   | MEMBER 
       { let mMember = rhs parseState 1
-        OverrideMemberFlags(MemberSynMemberFlagsTrivia mMember) }
+        OverrideMemberFlags, (SynLeadingKeyword.Member mMember) }
   | OVERRIDE 
       { let mOverride = rhs parseState 1
-        OverrideMemberFlags(OverrideSynMemberFlagsTrivia mOverride) }
+        OverrideMemberFlags, (SynLeadingKeyword.Override mOverride) }
 
 
 /* The core of the right-hand-side of a simple type definition */
@@ -2415,18 +2447,18 @@ recdFieldDeclList:
 recdFieldDecl: 
   | opt_attributes fieldDecl
      { let mWhole = rhs2 parseState 1 2
-       let fld = $2 $1 false mWhole
-       let (SynField (a, b, c, d, e, xmlDoc, vis, mWhole)) = fld
+       let fld = $2 $1 false mWhole None
+       let (SynField (a, b, c, d, e, xmlDoc, vis, mWhole, trivia)) = fld
        if Option.isSome vis then errorR (Error (FSComp.SR.parsRecordFieldsCannotHaveVisibilityDeclarations (), rhs parseState 2))
        let mWhole = unionRangeWithXmlDoc xmlDoc mWhole
-       SynField (a, b, c, d, e, xmlDoc, None, mWhole) }
+       SynField (a, b, c, d, e, xmlDoc, None, mWhole, trivia) }
 
 /* Part of a field or val declaration in a record type or object type */
 fieldDecl: 
   | opt_mutable opt_access ident COLON  typ 
-     { fun attrs stat mWhole ->
+     { fun attrs stat mWhole leadingKeyword ->
            let xmlDoc = grabXmlDocAtRangeStart(parseState, attrs, mWhole)
-           SynField(attrs, stat, Some $3, $5, $1, xmlDoc, $2, mWhole) }
+           SynField(attrs, stat, Some $3, $5, $1, xmlDoc, $2, mWhole, { LeadingKeyword = leadingKeyword }) }
 
 /* An exception definition */
 exconDefn: 
@@ -2465,7 +2497,13 @@ defnBindings:
   | LET opt_rec localBindings 
       { let mLetKwd = rhs parseState 1 
         let isUse = $1
-        let isRec = $2 
+        let isRec = $2
+        let leadingKeyword =
+            if isRec then
+                SynLeadingKeyword.LetRec(mLetKwd, rhs parseState 2)
+            else
+                SynLeadingKeyword.Let(mLetKwd)
+
         let localBindingsLastRangeOpt, localBindingsBuilder = $3
         
         // Calculate the precise range of the binding set, up to the end of the last r.h.s. expression
@@ -2479,7 +2517,7 @@ defnBindings:
             (fun attrs vis ->
                 let xmlDoc = grabXmlDoc(parseState, attrs, 1)
                 // apply the builder
-                let binds = localBindingsBuilder xmlDoc attrs vis mLetKwd
+                let binds = localBindingsBuilder xmlDoc attrs vis leadingKeyword
                 if not isRec && not (isNilOrSingleton binds) then 
                       reportParseErrorAt mLetKwd (FSComp.SR.parsLetAndForNonRecBindings())
                 [], binds),
@@ -2497,7 +2535,7 @@ doBinding:
         let mWhole = unionRanges mDoKwd $2.Range
         // any attributes prior to the 'let' are left free, e.g. become top-level attributes 
         // associated with the module, 'main' function or assembly depending on their target 
-        BindingSetPreAttrs(mDoKwd, false, false, (fun attrs vis -> attrs, [mkSynDoBinding (vis, $2, mWhole)]), mWhole) }
+        BindingSetPreAttrs(mDoKwd, false, false, (fun attrs vis -> attrs, [mkSynDoBinding (vis, mDoKwd, $2, mWhole)]), mWhole) }
 
 
 /* A 'let ....' binding in the #light syntax */
@@ -2506,6 +2544,16 @@ hardwhiteLetBindings:
       { let mLetKwd = rhs parseState 1 
         let isUse = $1
         let isRec = $2
+        let leadingKeyword =
+            if not isUse && isRec then
+                SynLeadingKeyword.LetRec(mLetKwd, rhs parseState 2)
+            elif isUse && not isRec then
+                SynLeadingKeyword.Use mLetKwd
+            elif isUse && isRec then
+                SynLeadingKeyword.UseRec(mLetKwd, rhs parseState 2)
+            else
+                SynLeadingKeyword.Let(mLetKwd)
+
         let report, mIn = $4
         report (if isUse then "use" else "let") mLetKwd  // report unterminated error 
         
@@ -2521,7 +2569,7 @@ hardwhiteLetBindings:
         BindingSetPreAttrs(mLetKwd, isRec, isUse,
           (fun attrs vis ->
             let xmlDoc = grabXmlDoc(parseState, attrs, 1)
-            let binds = localBindingsBuilder xmlDoc attrs vis mLetKwd
+            let binds = localBindingsBuilder xmlDoc attrs vis leadingKeyword
             if not isRec && not (isNilOrSingleton binds) then
                 reportParseErrorAt mLetKwd (FSComp.SR.parsLetAndForNonRecBindings())
             [], binds),
@@ -2533,12 +2581,12 @@ hardwhiteLetBindings:
 /* A 'do ...' statement */
 hardwhiteDoBinding: 
   | ODO typedSequentialExprBlock hardwhiteDefnBindingsTerminator          
-      { let mLetKwd = rhs parseState 1 
-        let bindingSetRange = unionRanges mLetKwd $2.Range 
+      { let mDoKwd = rhs parseState 1 
+        let bindingSetRange = unionRanges mDoKwd $2.Range 
         let seqPt = DebugPointAtBinding.NoneAtDo 
         // any attributes prior to the 'let' are left free, e.g. become top-level attributes 
         // associated with the module, 'main' function or assembly depending on their target 
-        BindingSetPreAttrs(mLetKwd, false, false, (fun attrs vis -> attrs, [mkSynDoBinding (vis, $2, bindingSetRange)]), bindingSetRange), $2 }
+        BindingSetPreAttrs(mDoKwd, false, false, (fun attrs vis -> attrs, [mkSynDoBinding (vis, mDoKwd, $2, bindingSetRange)]), bindingSetRange), $2 }
 
 
 /* The bindings in a class type definition */
@@ -2595,7 +2643,7 @@ cPrototype:
             let bindingPat = SynPat.LongIdent (SynLongIdent([nm], [], [None]), None, Some noInferredTypars, SynArgPats.Pats [SynPat.Tuple(false, args, argsm)], vis, nmm)
             let mWholeBindLhs = (mBindLhs, attrs) ||> unionRangeWithListBy (fun (a: SynAttributeList) -> a.Range)
             let xmlDoc = grabXmlDoc(parseState, attrs, 1)
-            let trivia = { LetKeyword = None; ExternKeyword = Some mExtern; EqualsRange = None }
+            let trivia = { LeadingKeyword = SynLeadingKeyword.Extern mExtern; EqualsRange = None }
             let binding =
                 mkSynBinding 
                     (xmlDoc, bindingPat) 
@@ -2673,19 +2721,19 @@ localBindings:
                match moreLocalBindingsLastRange with 
                | None -> localBindingRange 
                | Some m -> m
-           Some lastRange, (fun xmlDoc attrs vis mLetKwd -> attrLocalBindingBuilder xmlDoc attrs vis mLetKwd true ::  moreBindings)
+           Some lastRange, (fun xmlDoc attrs vis leadingKeyword -> attrLocalBindingBuilder xmlDoc attrs vis leadingKeyword true ::  moreBindings)
         | None -> 
-           moreLocalBindingsLastRange, (fun _xmlDoc _attrs _vis _letm -> moreBindings) }
+           moreLocalBindingsLastRange, (fun _xmlDoc _attrs _vis _leadingKeyword -> moreBindings) }
 
 
 moreLocalBindings: 
   | AND attr_localBinding moreLocalBindings 
-      { let mLetKwd = rhs parseState 1
+      { let leadingKeyword = SynLeadingKeyword.And(rhs parseState 1)
         (match $2 with 
          | Some (localBindingRange, attrLocalBindingBuilder) ->
             let xmlDoc = grabXmlDoc(parseState, [], 1)
             let xmlDoc = if xmlDoc.IsEmpty then grabXmlDoc(parseState, [], 2) else xmlDoc
-            (attrLocalBindingBuilder xmlDoc [] None mLetKwd false, localBindingRange) :: $3
+            (attrLocalBindingBuilder xmlDoc [] None leadingKeyword false, localBindingRange) :: $3
          | None -> $3) }
 
   | %prec prec_no_more_attr_bindings 
@@ -2697,7 +2745,7 @@ attr_localBinding:
   | opt_attributes localBinding 
       { let attrs2 = $1
         let localBindingRange, localBindingBuilder = $2
-        let attrLocalBindingBuilder = (fun xmlDoc attrs vis mLetKwd _ -> localBindingBuilder xmlDoc (attrs@attrs2) vis mLetKwd)
+        let attrLocalBindingBuilder = (fun xmlDoc attrs vis leadingKeyword _ -> localBindingBuilder xmlDoc (attrs@attrs2) vis leadingKeyword)
         Some(localBindingRange, attrLocalBindingBuilder) }
 
   | error 
@@ -2714,11 +2762,11 @@ localBinding:
         let bindingPat, mBindLhs = $3 
         let localBindingRange = unionRanges (rhs2 parseState 1 5) mRhs
         let localBindingBuilder = 
-          (fun xmlDoc attrs vis mLetKwd ->
-            let mWhole = (unionRanges mLetKwd mRhs, attrs) ||> unionRangeWithListBy (fun (a: SynAttributeList) -> a.Range)
+          (fun xmlDoc attrs vis (leadingKeyword: SynLeadingKeyword) ->
+            let mWhole = (unionRanges leadingKeyword.Range mRhs, attrs) ||> unionRangeWithListBy (fun (a: SynAttributeList) -> a.Range)
             let spBind = if IsDebugPointBinding bindingPat expr then DebugPointAtBinding.Yes mWhole else DebugPointAtBinding.NoneAtLet
             let mWholeBindLhs = (mBindLhs, attrs) ||> unionRangeWithListBy (fun (a: SynAttributeList) -> a.Range)
-            let trivia: SynBindingTrivia = { LetKeyword = Some mLetKwd; EqualsRange = Some mEquals; ExternKeyword = None }
+            let trivia: SynBindingTrivia = { LeadingKeyword = leadingKeyword; EqualsRange = Some mEquals }
             mkSynBinding (xmlDoc, bindingPat) (vis, $1, $2, mWholeBindLhs, spBind, optReturnType, expr, mRhs, opts, attrs, None, trivia))
         localBindingRange, localBindingBuilder }
 
@@ -2728,12 +2776,12 @@ localBinding:
         let optReturnType = $4 
         let bindingPat, mBindLhs = $3
         let localBindingBuilder = 
-          (fun xmlDoc attrs vis mLetKwd ->
+          (fun xmlDoc attrs vis leadingKeyword ->
             let mEquals = rhs parseState 5
             let zeroWidthAtEnd = mEquals.EndRange
             let rhsExpr = arbExpr("localBinding1", zeroWidthAtEnd)
             let spBind = if IsDebugPointBinding bindingPat rhsExpr then DebugPointAtBinding.Yes mWhole else DebugPointAtBinding.NoneAtLet
-            let trivia: SynBindingTrivia = { LetKeyword = Some mLetKwd; EqualsRange = Some mEquals; ExternKeyword = None }
+            let trivia: SynBindingTrivia = { LeadingKeyword = leadingKeyword; EqualsRange = Some mEquals }
             mkSynBinding (xmlDoc, bindingPat) (vis, $1, $2, mBindLhs, spBind, optReturnType, rhsExpr, mRhs, [], attrs, None, trivia))
         mWhole, localBindingBuilder }
 
@@ -2744,9 +2792,9 @@ localBinding:
         let mRhs = mWhole.EndRange  // zero-width range at end of last good token
         let bindingPat, mBindLhs = $3 
         let localBindingBuilder = 
-          (fun xmlDoc attrs vis mLetKwd ->
-            let spBind = DebugPointAtBinding.Yes (unionRanges mLetKwd mRhs)
-            let trivia = { LetKeyword = Some mLetKwd; EqualsRange = None; ExternKeyword = None }
+          (fun xmlDoc attrs vis (leadingKeyword: SynLeadingKeyword) ->
+            let spBind = DebugPointAtBinding.Yes (unionRanges leadingKeyword.Range mRhs)
+            let trivia = { LeadingKeyword = leadingKeyword; EqualsRange = None }
             let rhsExpr = arbExpr("localBinding2", mRhs)
             mkSynBinding (xmlDoc, bindingPat) (vis, $1, $2, mBindLhs, spBind, optReturnType, rhsExpr, mRhs, [], attrs, None, trivia))
         mWhole, localBindingBuilder }
@@ -4793,12 +4841,12 @@ objExprBindings:
   | WITH localBindings 
       { let mWithKwd = (rhs parseState 1)
         let _localBindingsLastRange, localBindingsBuilder = $2 
-        mWithKwd, (localBindingsBuilder PreXmlDoc.Empty [] None mWithKwd), [] }
+        mWithKwd, (localBindingsBuilder PreXmlDoc.Empty [] None SynLeadingKeyword.Synthetic), [] }
 
   | OWITH localBindings OEND
       { let mWithKwd = (rhs parseState 1)
         let _localBindingsLastRange, localBindingsBuilder = $2 
-        mWithKwd, (localBindingsBuilder PreXmlDoc.Empty [] None mWithKwd), [] }
+        mWithKwd, (localBindingsBuilder PreXmlDoc.Empty [] None SynLeadingKeyword.Synthetic), [] }
 
   | WITH objectImplementationBlock opt_declEnd
       { let mWithKwd = rhs parseState 1
@@ -5252,7 +5300,7 @@ atomTypeOrAnonRecdType:
      { let flds, isStruct = $1
        let flds2 = 
            flds |> List.choose (function 
-             | (SynField([], false, Some id, ty, false, _xmldoc, None, _m)) -> Some (id, ty) 
+             | (SynField([], false, Some id, ty, false, _xmldoc, None, _m, _trivia)) -> Some (id, ty) 
              | _ -> reportParseErrorAt (rhs parseState 1) (FSComp.SR.parsInvalidAnonRecdType()); None)
        SynType.AnonRecd (isStruct, flds2, rhs parseState 1) }  
 
diff --git a/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.Tests.fsproj b/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.Tests.fsproj
index c5b206ed9e6..279296ec02c 100644
--- a/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.Tests.fsproj
+++ b/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.Tests.fsproj
@@ -128,6 +128,9 @@
     <Compile Include="..\service\SyntaxTreeTests\ExternTests.fs">
       <Link>SyntaxTree\ExternTests.fs</Link>
     </Compile>
+    <Compile Include="..\service\SyntaxTreeTests\LeadingKeywordTests.fs">
+      <Link>SyntaxTree\LeadingKeywordTests.fs</Link>
+    </Compile>
     <Compile Include="..\service\FileSystemTests.fs">
       <Link>FileSystemTests.fs</Link>
     </Compile>
diff --git a/tests/FSharp.Compiler.Service.Tests/FSharp.CompilerService.SurfaceArea.netstandard.expected b/tests/FSharp.Compiler.Service.Tests/FSharp.CompilerService.SurfaceArea.netstandard.expected
index d7f8a490d26..66c52c10aed 100644
--- a/tests/FSharp.Compiler.Service.Tests/FSharp.CompilerService.SurfaceArea.netstandard.expected
+++ b/tests/FSharp.Compiler.Service.Tests/FSharp.CompilerService.SurfaceArea.netstandard.expected
@@ -7157,9 +7157,11 @@ FSharp.Compiler.Syntax.SynField: Boolean get_isMutable()
 FSharp.Compiler.Syntax.SynField: Boolean get_isStatic()
 FSharp.Compiler.Syntax.SynField: Boolean isMutable
 FSharp.Compiler.Syntax.SynField: Boolean isStatic
-FSharp.Compiler.Syntax.SynField: FSharp.Compiler.Syntax.SynField NewSynField(Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynAttributeList], Boolean, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.Ident], FSharp.Compiler.Syntax.SynType, Boolean, FSharp.Compiler.Xml.PreXmlDoc, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynAccess], FSharp.Compiler.Text.Range)
+FSharp.Compiler.Syntax.SynField: FSharp.Compiler.Syntax.SynField NewSynField(Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynAttributeList], Boolean, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.Ident], FSharp.Compiler.Syntax.SynType, Boolean, FSharp.Compiler.Xml.PreXmlDoc, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynAccess], FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynFieldTrivia)
 FSharp.Compiler.Syntax.SynField: FSharp.Compiler.Syntax.SynType fieldType
 FSharp.Compiler.Syntax.SynField: FSharp.Compiler.Syntax.SynType get_fieldType()
+FSharp.Compiler.Syntax.SynField: FSharp.Compiler.SyntaxTrivia.SynFieldTrivia get_trivia()
+FSharp.Compiler.Syntax.SynField: FSharp.Compiler.SyntaxTrivia.SynFieldTrivia trivia
 FSharp.Compiler.Syntax.SynField: FSharp.Compiler.Text.Range get_range()
 FSharp.Compiler.Syntax.SynField: FSharp.Compiler.Text.Range range
 FSharp.Compiler.Syntax.SynField: FSharp.Compiler.Xml.PreXmlDoc get_xmlDoc()
@@ -7374,8 +7376,8 @@ FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: FSharp.Compiler.Syntax.SynMem
 FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: FSharp.Compiler.Syntax.SynMemberFlags memberFlagsForSet
 FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: FSharp.Compiler.Syntax.SynMemberKind get_propKind()
 FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: FSharp.Compiler.Syntax.SynMemberKind propKind
-FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: FSharp.Compiler.Text.Range equalsRange
-FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: FSharp.Compiler.Text.Range get_equalsRange()
+FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia get_trivia()
+FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia trivia
 FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: FSharp.Compiler.Text.Range get_range()
 FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: FSharp.Compiler.Text.Range range
 FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: FSharp.Compiler.Xml.PreXmlDoc get_xmlDoc()
@@ -7386,10 +7388,6 @@ FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: Microsoft.FSharp.Core.FSharpO
 FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynAccess] get_accessibility()
 FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynType] get_typeOpt()
 FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynType] typeOpt
-FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] getSetRange
-FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_getSetRange()
-FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_withKeyword()
-FSharp.Compiler.Syntax.SynMemberDefn+AutoProperty: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] withKeyword
 FSharp.Compiler.Syntax.SynMemberDefn+GetSetMember: FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia get_trivia()
 FSharp.Compiler.Syntax.SynMemberDefn+GetSetMember: FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia trivia
 FSharp.Compiler.Syntax.SynMemberDefn+GetSetMember: FSharp.Compiler.Text.Range get_range()
@@ -7495,7 +7493,7 @@ FSharp.Compiler.Syntax.SynMemberDefn: Boolean get_IsNestedType()
 FSharp.Compiler.Syntax.SynMemberDefn: Boolean get_IsOpen()
 FSharp.Compiler.Syntax.SynMemberDefn: Boolean get_IsValField()
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewAbstractSlot(FSharp.Compiler.Syntax.SynValSig, FSharp.Compiler.Syntax.SynMemberFlags, FSharp.Compiler.Text.Range)
-FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewAutoProperty(Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynAttributeList], Boolean, FSharp.Compiler.Syntax.Ident, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynType], FSharp.Compiler.Syntax.SynMemberKind, FSharp.Compiler.Syntax.SynMemberFlags, FSharp.Compiler.Syntax.SynMemberFlags, FSharp.Compiler.Xml.PreXmlDoc, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynAccess], FSharp.Compiler.Text.Range, FSharp.Compiler.Syntax.SynExpr, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], FSharp.Compiler.Text.Range)
+FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewAutoProperty(Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynAttributeList], Boolean, FSharp.Compiler.Syntax.Ident, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynType], FSharp.Compiler.Syntax.SynMemberKind, FSharp.Compiler.Syntax.SynMemberFlags, FSharp.Compiler.Syntax.SynMemberFlags, FSharp.Compiler.Xml.PreXmlDoc, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynAccess], FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia)
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewGetSetMember(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynBinding], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynBinding], FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia)
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewImplicitCtor(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynAccess], Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynAttributeList], FSharp.Compiler.Syntax.SynSimplePats, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.Ident], FSharp.Compiler.Xml.PreXmlDoc, FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewImplicitInherit(FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Syntax.SynExpr, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.Ident], FSharp.Compiler.Text.Range)
@@ -7538,11 +7536,9 @@ FSharp.Compiler.Syntax.SynMemberFlags: Boolean get_IsInstance()
 FSharp.Compiler.Syntax.SynMemberFlags: Boolean get_IsOverrideOrExplicitImpl()
 FSharp.Compiler.Syntax.SynMemberFlags: FSharp.Compiler.Syntax.SynMemberKind MemberKind
 FSharp.Compiler.Syntax.SynMemberFlags: FSharp.Compiler.Syntax.SynMemberKind get_MemberKind()
-FSharp.Compiler.Syntax.SynMemberFlags: FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia Trivia
-FSharp.Compiler.Syntax.SynMemberFlags: FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia get_Trivia()
 FSharp.Compiler.Syntax.SynMemberFlags: Int32 GetHashCode()
 FSharp.Compiler.Syntax.SynMemberFlags: System.String ToString()
-FSharp.Compiler.Syntax.SynMemberFlags: Void .ctor(Boolean, Boolean, Boolean, Boolean, Boolean, FSharp.Compiler.Syntax.SynMemberKind, FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia)
+FSharp.Compiler.Syntax.SynMemberFlags: Void .ctor(Boolean, Boolean, Boolean, Boolean, Boolean, FSharp.Compiler.Syntax.SynMemberKind)
 FSharp.Compiler.Syntax.SynMemberKind
 FSharp.Compiler.Syntax.SynMemberKind+Tags: Int32 ClassConstructor
 FSharp.Compiler.Syntax.SynMemberKind+Tags: Int32 Constructor
@@ -9417,14 +9413,12 @@ FSharp.Compiler.SyntaxTrivia.SynArgPatsNamePatPairsTrivia: Void .ctor(FSharp.Com
 FSharp.Compiler.SyntaxTrivia.SynBindingTrivia
 FSharp.Compiler.SyntaxTrivia.SynBindingTrivia: FSharp.Compiler.SyntaxTrivia.SynBindingTrivia Zero
 FSharp.Compiler.SyntaxTrivia.SynBindingTrivia: FSharp.Compiler.SyntaxTrivia.SynBindingTrivia get_Zero()
+FSharp.Compiler.SyntaxTrivia.SynBindingTrivia: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword LeadingKeyword
+FSharp.Compiler.SyntaxTrivia.SynBindingTrivia: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword get_LeadingKeyword()
 FSharp.Compiler.SyntaxTrivia.SynBindingTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] EqualsRange
-FSharp.Compiler.SyntaxTrivia.SynBindingTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] ExternKeyword
-FSharp.Compiler.SyntaxTrivia.SynBindingTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] LetKeyword
 FSharp.Compiler.SyntaxTrivia.SynBindingTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_EqualsRange()
-FSharp.Compiler.SyntaxTrivia.SynBindingTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_ExternKeyword()
-FSharp.Compiler.SyntaxTrivia.SynBindingTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_LetKeyword()
 FSharp.Compiler.SyntaxTrivia.SynBindingTrivia: System.String ToString()
-FSharp.Compiler.SyntaxTrivia.SynBindingTrivia: Void .ctor(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range])
+FSharp.Compiler.SyntaxTrivia.SynBindingTrivia: Void .ctor(FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range])
 FSharp.Compiler.SyntaxTrivia.SynEnumCaseTrivia
 FSharp.Compiler.SyntaxTrivia.SynEnumCaseTrivia: FSharp.Compiler.Text.Range EqualsRange
 FSharp.Compiler.SyntaxTrivia.SynEnumCaseTrivia: FSharp.Compiler.Text.Range get_EqualsRange()
@@ -9503,6 +9497,234 @@ FSharp.Compiler.SyntaxTrivia.SynExprTryWithTrivia: FSharp.Compiler.Text.Range ge
 FSharp.Compiler.SyntaxTrivia.SynExprTryWithTrivia: FSharp.Compiler.Text.Range get_WithToEndRange()
 FSharp.Compiler.SyntaxTrivia.SynExprTryWithTrivia: System.String ToString()
 FSharp.Compiler.SyntaxTrivia.SynExprTryWithTrivia: Void .ctor(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynFieldTrivia
+FSharp.Compiler.SyntaxTrivia.SynFieldTrivia: FSharp.Compiler.SyntaxTrivia.SynFieldTrivia Zero
+FSharp.Compiler.SyntaxTrivia.SynFieldTrivia: FSharp.Compiler.SyntaxTrivia.SynFieldTrivia get_Zero()
+FSharp.Compiler.SyntaxTrivia.SynFieldTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword] LeadingKeyword
+FSharp.Compiler.SyntaxTrivia.SynFieldTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword] get_LeadingKeyword()
+FSharp.Compiler.SyntaxTrivia.SynFieldTrivia: System.String ToString()
+FSharp.Compiler.SyntaxTrivia.SynFieldTrivia: Void .ctor(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword])
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Abstract: FSharp.Compiler.Text.Range abstractRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Abstract: FSharp.Compiler.Text.Range get_abstractRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+AbstractMember: FSharp.Compiler.Text.Range abstractRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+AbstractMember: FSharp.Compiler.Text.Range get_abstractRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+AbstractMember: FSharp.Compiler.Text.Range get_memberRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+AbstractMember: FSharp.Compiler.Text.Range memberRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+And: FSharp.Compiler.Text.Range andRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+And: FSharp.Compiler.Text.Range get_andRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Default: FSharp.Compiler.Text.Range defaultRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Default: FSharp.Compiler.Text.Range get_defaultRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+DefaultVal: FSharp.Compiler.Text.Range defaultRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+DefaultVal: FSharp.Compiler.Text.Range get_defaultRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+DefaultVal: FSharp.Compiler.Text.Range get_valRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+DefaultVal: FSharp.Compiler.Text.Range valRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Do: FSharp.Compiler.Text.Range doRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Do: FSharp.Compiler.Text.Range get_doRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Extern: FSharp.Compiler.Text.Range externRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Extern: FSharp.Compiler.Text.Range get_externRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Let: FSharp.Compiler.Text.Range get_letRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Let: FSharp.Compiler.Text.Range letRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+LetRec: FSharp.Compiler.Text.Range get_letRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+LetRec: FSharp.Compiler.Text.Range get_recRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+LetRec: FSharp.Compiler.Text.Range letRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+LetRec: FSharp.Compiler.Text.Range recRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Member: FSharp.Compiler.Text.Range get_memberRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Member: FSharp.Compiler.Text.Range memberRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+MemberVal: FSharp.Compiler.Text.Range get_memberRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+MemberVal: FSharp.Compiler.Text.Range get_valRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+MemberVal: FSharp.Compiler.Text.Range memberRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+MemberVal: FSharp.Compiler.Text.Range valRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+New: FSharp.Compiler.Text.Range get_newRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+New: FSharp.Compiler.Text.Range newRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Override: FSharp.Compiler.Text.Range get_overrideRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Override: FSharp.Compiler.Text.Range overrideRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+OverrideVal: FSharp.Compiler.Text.Range get_overrideRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+OverrideVal: FSharp.Compiler.Text.Range get_valRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+OverrideVal: FSharp.Compiler.Text.Range overrideRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+OverrideVal: FSharp.Compiler.Text.Range valRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticAbstract: FSharp.Compiler.Text.Range abstractRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticAbstract: FSharp.Compiler.Text.Range get_abstractRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticAbstract: FSharp.Compiler.Text.Range get_staticRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticAbstract: FSharp.Compiler.Text.Range staticRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticAbstractMember: FSharp.Compiler.Text.Range abstractMember
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticAbstractMember: FSharp.Compiler.Text.Range get_abstractMember()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticAbstractMember: FSharp.Compiler.Text.Range get_memberRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticAbstractMember: FSharp.Compiler.Text.Range get_staticRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticAbstractMember: FSharp.Compiler.Text.Range memberRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticAbstractMember: FSharp.Compiler.Text.Range staticRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticDo: FSharp.Compiler.Text.Range doRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticDo: FSharp.Compiler.Text.Range get_doRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticDo: FSharp.Compiler.Text.Range get_staticRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticDo: FSharp.Compiler.Text.Range staticRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticLet: FSharp.Compiler.Text.Range get_letRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticLet: FSharp.Compiler.Text.Range get_staticRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticLet: FSharp.Compiler.Text.Range letRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticLet: FSharp.Compiler.Text.Range staticRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticLetRec: FSharp.Compiler.Text.Range get_letRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticLetRec: FSharp.Compiler.Text.Range get_recRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticLetRec: FSharp.Compiler.Text.Range get_staticRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticLetRec: FSharp.Compiler.Text.Range letRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticLetRec: FSharp.Compiler.Text.Range recRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticLetRec: FSharp.Compiler.Text.Range staticRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticMember: FSharp.Compiler.Text.Range get_memberRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticMember: FSharp.Compiler.Text.Range get_staticRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticMember: FSharp.Compiler.Text.Range memberRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticMember: FSharp.Compiler.Text.Range staticRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticMemberVal: FSharp.Compiler.Text.Range get_memberRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticMemberVal: FSharp.Compiler.Text.Range get_staticRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticMemberVal: FSharp.Compiler.Text.Range get_valRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticMemberVal: FSharp.Compiler.Text.Range memberRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticMemberVal: FSharp.Compiler.Text.Range staticRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticMemberVal: FSharp.Compiler.Text.Range valRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticVal: FSharp.Compiler.Text.Range get_staticRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticVal: FSharp.Compiler.Text.Range get_valRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticVal: FSharp.Compiler.Text.Range staticRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticVal: FSharp.Compiler.Text.Range valRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 Abstract
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 AbstractMember
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 And
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 Default
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 DefaultVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 Do
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 Extern
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 Let
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 LetRec
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 Member
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 MemberVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 New
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 Override
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 OverrideVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 StaticAbstract
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 StaticAbstractMember
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 StaticDo
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 StaticLet
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 StaticLetRec
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 StaticMember
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 StaticMemberVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 StaticVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 Synthetic
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 Use
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 UseRec
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags: Int32 Val
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Use: FSharp.Compiler.Text.Range get_useRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Use: FSharp.Compiler.Text.Range useRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+UseRec: FSharp.Compiler.Text.Range get_recRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+UseRec: FSharp.Compiler.Text.Range get_useRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+UseRec: FSharp.Compiler.Text.Range recRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+UseRec: FSharp.Compiler.Text.Range useRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Val: FSharp.Compiler.Text.Range get_valRange()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Val: FSharp.Compiler.Text.Range valRange
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsAbstract
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsAbstractMember
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsAnd
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsDefault
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsDefaultVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsDo
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsExtern
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsLet
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsLetRec
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsMember
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsMemberVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsNew
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsOverride
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsOverrideVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsStaticAbstract
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsStaticAbstractMember
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsStaticDo
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsStaticLet
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsStaticLetRec
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsStaticMember
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsStaticMemberVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsStaticVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsSynthetic
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsUse
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsUseRec
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean IsVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsAbstract()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsAbstractMember()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsAnd()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsDefault()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsDefaultVal()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsDo()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsExtern()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsLet()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsLetRec()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsMember()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsMemberVal()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsNew()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsOverride()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsOverrideVal()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsStaticAbstract()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsStaticAbstractMember()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsStaticDo()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsStaticLet()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsStaticLetRec()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsStaticMember()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsStaticMemberVal()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsStaticVal()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsSynthetic()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsUse()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsUseRec()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Boolean get_IsVal()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewAbstract(FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewAbstractMember(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewAnd(FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewDefault(FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewDefaultVal(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewDo(FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewExtern(FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewLet(FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewLetRec(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewMember(FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewMemberVal(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewNew(FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewOverride(FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewOverrideVal(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewStaticAbstract(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewStaticAbstractMember(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewStaticDo(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewStaticLet(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewStaticLetRec(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewStaticMember(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewStaticMemberVal(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewStaticVal(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewUse(FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewUseRec(FSharp.Compiler.Text.Range, FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword NewVal(FSharp.Compiler.Text.Range)
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword Synthetic
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword get_Synthetic()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Abstract
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+AbstractMember
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+And
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Default
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+DefaultVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Do
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Extern
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Let
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+LetRec
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Member
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+MemberVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+New
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Override
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+OverrideVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticAbstract
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticAbstractMember
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticDo
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticLet
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticLetRec
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticMember
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticMemberVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+StaticVal
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Tags
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Use
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+UseRec
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword+Val
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.Text.Range Range
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: FSharp.Compiler.Text.Range get_Range()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Int32 Tag
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: Int32 get_Tag()
+FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword: System.String ToString()
 FSharp.Compiler.SyntaxTrivia.SynMatchClauseTrivia
 FSharp.Compiler.SyntaxTrivia.SynMatchClauseTrivia: FSharp.Compiler.SyntaxTrivia.SynMatchClauseTrivia Zero
 FSharp.Compiler.SyntaxTrivia.SynMatchClauseTrivia: FSharp.Compiler.SyntaxTrivia.SynMatchClauseTrivia get_Zero()
@@ -9512,21 +9734,17 @@ FSharp.Compiler.SyntaxTrivia.SynMatchClauseTrivia: Microsoft.FSharp.Core.FSharpO
 FSharp.Compiler.SyntaxTrivia.SynMatchClauseTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_BarRange()
 FSharp.Compiler.SyntaxTrivia.SynMatchClauseTrivia: System.String ToString()
 FSharp.Compiler.SyntaxTrivia.SynMatchClauseTrivia: Void .ctor(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range])
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia Zero
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia get_Zero()
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] AbstractRange
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] DefaultRange
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] MemberRange
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] OverrideRange
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] StaticRange
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_AbstractRange()
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_DefaultRange()
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_MemberRange()
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_OverrideRange()
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_StaticRange()
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: System.String ToString()
-FSharp.Compiler.SyntaxTrivia.SynMemberFlagsTrivia: Void .ctor(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range])
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword LeadingKeyword
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword get_LeadingKeyword()
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] EqualsRange
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] GetSetKeyword
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] WithKeyword
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_EqualsRange()
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_GetSetKeyword()
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_WithKeyword()
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: System.String ToString()
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: Void .ctor(FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range])
 FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia
 FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia: FSharp.Compiler.Text.Range WithKeyword
 FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia: FSharp.Compiler.Text.Range get_WithKeyword()
@@ -9608,8 +9826,13 @@ FSharp.Compiler.SyntaxTrivia.SynTypeFunTrivia: FSharp.Compiler.Text.Range get_Ar
 FSharp.Compiler.SyntaxTrivia.SynTypeFunTrivia: System.String ToString()
 FSharp.Compiler.SyntaxTrivia.SynTypeFunTrivia: Void .ctor(FSharp.Compiler.Text.Range)
 FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia
+FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia: Boolean Equals(FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia)
+FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia: Boolean Equals(System.Object)
+FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia: Boolean Equals(System.Object, System.Collections.IEqualityComparer)
 FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia: FSharp.Compiler.Text.Range OrKeyword
 FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia: FSharp.Compiler.Text.Range get_OrKeyword()
+FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia: Int32 GetHashCode()
+FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia: Int32 GetHashCode(System.Collections.IEqualityComparer)
 FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia: System.String ToString()
 FSharp.Compiler.SyntaxTrivia.SynTypeOrTrivia: Void .ctor(FSharp.Compiler.Text.Range)
 FSharp.Compiler.SyntaxTrivia.SynUnionCaseTrivia
@@ -9618,16 +9841,16 @@ FSharp.Compiler.SyntaxTrivia.SynUnionCaseTrivia: Microsoft.FSharp.Core.FSharpOpt
 FSharp.Compiler.SyntaxTrivia.SynUnionCaseTrivia: System.String ToString()
 FSharp.Compiler.SyntaxTrivia.SynUnionCaseTrivia: Void .ctor(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range])
 FSharp.Compiler.SyntaxTrivia.SynValSigTrivia
+FSharp.Compiler.SyntaxTrivia.SynValSigTrivia: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword LeadingKeyword
+FSharp.Compiler.SyntaxTrivia.SynValSigTrivia: FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword get_LeadingKeyword()
 FSharp.Compiler.SyntaxTrivia.SynValSigTrivia: FSharp.Compiler.SyntaxTrivia.SynValSigTrivia Zero
 FSharp.Compiler.SyntaxTrivia.SynValSigTrivia: FSharp.Compiler.SyntaxTrivia.SynValSigTrivia get_Zero()
 FSharp.Compiler.SyntaxTrivia.SynValSigTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] EqualsRange
-FSharp.Compiler.SyntaxTrivia.SynValSigTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] ValKeyword
 FSharp.Compiler.SyntaxTrivia.SynValSigTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] WithKeyword
 FSharp.Compiler.SyntaxTrivia.SynValSigTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_EqualsRange()
-FSharp.Compiler.SyntaxTrivia.SynValSigTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_ValKeyword()
 FSharp.Compiler.SyntaxTrivia.SynValSigTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_WithKeyword()
 FSharp.Compiler.SyntaxTrivia.SynValSigTrivia: System.String ToString()
-FSharp.Compiler.SyntaxTrivia.SynValSigTrivia: Void .ctor(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range])
+FSharp.Compiler.SyntaxTrivia.SynValSigTrivia: Void .ctor(FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range])
 FSharp.Compiler.Text.ISourceText
 FSharp.Compiler.Text.ISourceText: Boolean ContentEquals(FSharp.Compiler.Text.ISourceText)
 FSharp.Compiler.Text.ISourceText: Boolean SubTextEquals(System.String, Int32)
diff --git a/tests/service/SyntaxTreeTests/BindingTests.fs b/tests/service/SyntaxTreeTests/BindingTests.fs
index 95ea6685947..5a05af975e2 100644
--- a/tests/service/SyntaxTreeTests/BindingTests.fs
+++ b/tests/service/SyntaxTreeTests/BindingTests.fs
@@ -2,6 +2,7 @@ module FSharp.Compiler.Service.Tests.SyntaxTreeTests.BindingTestsTests
 
 open FSharp.Compiler.Service.Tests.Common
 open FSharp.Compiler.Syntax
+open FSharp.Compiler.SyntaxTrivia
 open NUnit.Framework
 
 [<Test>]
@@ -329,7 +330,7 @@ let ``Range of let keyword should be present in SynModuleDecl.Let binding`` () =
 
     match parseResults with
     | ParsedInput.ImplFile (ParsedImplFileInput (contents = [ SynModuleOrNamespace.SynModuleOrNamespace(decls = [
-        SynModuleDecl.Let(bindings = [SynBinding(trivia={ LetKeyword = Some mLet })])
+        SynModuleDecl.Let(bindings = [SynBinding(trivia={ LeadingKeyword = SynLeadingKeyword.Let mLet })])
     ]) ])) ->
         assertRange (1, 0) (1, 3) mLet
     | _ -> Assert.Fail "Could not get valid AST"
@@ -346,7 +347,7 @@ let v = 12
 
     match parseResults with
     | ParsedInput.ImplFile (ParsedImplFileInput (contents = [ SynModuleOrNamespace.SynModuleOrNamespace(decls = [
-        SynModuleDecl.Let(bindings = [SynBinding(trivia={ LetKeyword = Some mLet })])
+        SynModuleDecl.Let(bindings = [SynBinding(trivia={ LeadingKeyword = SynLeadingKeyword.Let mLet })])
     ]) ])) ->
         assertRange (5, 0) (5, 3) mLet
     | _ -> Assert.Fail "Could not get valid AST"
@@ -362,7 +363,7 @@ let a =
 
     match parseResults with
     | ParsedInput.ImplFile (ParsedImplFileInput (contents = [ SynModuleOrNamespace.SynModuleOrNamespace(decls = [
-        SynModuleDecl.Let(bindings = [SynBinding(expr=SynExpr.LetOrUse(bindings=[SynBinding(trivia={ LetKeyword = Some mLet })]))])
+        SynModuleDecl.Let(bindings = [SynBinding(expr=SynExpr.LetOrUse(bindings=[SynBinding(trivia={ LeadingKeyword = SynLeadingKeyword.Let mLet })]))])
     ]) ])) ->
         assertRange (3, 4) (3, 7) mLet
     | _ -> Assert.Fail "Could not get valid AST"
diff --git a/tests/service/SyntaxTreeTests/ExternTests.fs b/tests/service/SyntaxTreeTests/ExternTests.fs
index 0599307d994..43ea6e5435a 100644
--- a/tests/service/SyntaxTreeTests/ExternTests.fs
+++ b/tests/service/SyntaxTreeTests/ExternTests.fs
@@ -13,7 +13,7 @@ let ``extern keyword is present in trivia`` () =
     | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
                 SynModuleOrNamespace.SynModuleOrNamespace(decls = [
                     SynModuleDecl.Let(bindings = [
-                        SynBinding(trivia = { ExternKeyword = Some mExtern  })
+                        SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.Extern mExtern  })
                     ])
                 ])
             ])) ->
diff --git a/tests/service/SyntaxTreeTests/LeadingKeywordTests.fs b/tests/service/SyntaxTreeTests/LeadingKeywordTests.fs
new file mode 100644
index 00000000000..c247376436b
--- /dev/null
+++ b/tests/service/SyntaxTreeTests/LeadingKeywordTests.fs
@@ -0,0 +1,561 @@
+module FSharp.Compiler.Service.Tests.SyntaxTreeTests.LeadingKeywordTests
+
+open FSharp.Compiler.Service.Tests.Common
+open FSharp.Compiler.Syntax
+open FSharp.Compiler.SyntaxTrivia
+open NUnit.Framework
+
+[<Test>]
+let ``let keyword`` () =
+    let parseResults = getParseResults "let a b = b + 1"
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Let(bindings = [
+                        SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.Let mLet  })
+                    ])
+                ])
+            ])) ->
+        assertRange (1, 0) (1, 3) mLet
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``let rec keyword`` () =
+    let parseResults = getParseResults "let rec a b = b + 1"
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Let(bindings = [
+                        SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.LetRec(mLet, mRec)  })
+                    ])
+                ])
+            ])) ->
+        assertRange (1, 0) (1, 3) mLet
+        assertRange (1, 4) (1, 7) mRec
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``and keyword`` () =
+    let parseResults =
+        getParseResults """
+let rec a b = b + 1
+and d e = e + 1
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Let(bindings = [
+                        SynBinding _
+                        SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.And mAnd  })
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 0) (3, 3) mAnd
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``use keyword`` () =
+    let parseResults =
+        getParseResults """
+do
+    use x = X()
+    ()
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Expr(expr =
+                        SynExpr.Do(expr =
+                            SynExpr.LetOrUse(bindings = [
+                                SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.Use mUse })
+                            ])
+                        )
+                    )
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 7) mUse
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``use rec keyword`` () =
+    let parseResults =
+        getParseResults """
+do
+    use rec x = X()
+    ()
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Expr(expr =
+                        SynExpr.Do(expr =
+                            SynExpr.LetOrUse(bindings = [
+                                SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.UseRec(mUse, mRec) })
+                            ])
+                        )
+                    )
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 7) mUse
+        assertRange (3, 8) (3, 11) mRec
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``extern keyword`` () =
+    let parseResults = getParseResults "extern void Meh()"
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Let(bindings = [
+                        SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.Extern mExtern  })
+                    ])
+                ])
+            ])) ->
+        assertRange (1, 0) (1, 6) mExtern
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``member keyword`` () =
+    let parseResults = getParseResults """
+type X =
+    member this.Y ()  = ()
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.Member(memberDefn = SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.Member mMember }))
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 10) mMember
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``member val keyword`` () =
+    let parseResults = getParseResults  """
+type X =
+    member val Y : int = 1
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.AutoProperty(trivia = { LeadingKeyword = SynLeadingKeyword.MemberVal(mMember, mVal) })
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 10) mMember
+        assertRange (3, 11) (3, 14) mVal
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``override keyword`` () =
+    let parseResults = getParseResults  """
+type D =
+    override E : string = ""
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.Member(memberDefn = SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.Override(mOverride) }))
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 12) mOverride
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``override val keyword`` () =
+    let parseResults = getParseResults  """
+type X =
+    override val Y : int = 1
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.AutoProperty(trivia = { LeadingKeyword = SynLeadingKeyword.OverrideVal(mOverride, mVal) })
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 12) mOverride
+        assertRange (3, 13) (3, 16) mVal
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``abstract keyword`` () =
+    let parseResults = getParseResults """
+type X =
+    abstract Y : int
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.AbstractSlot(slotSig = SynValSig(trivia = { LeadingKeyword = SynLeadingKeyword.Abstract mAbstract }))
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 12) mAbstract
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``abstract member keyword`` () =
+    let parseResults = getParseResults """
+type X =
+    abstract member Y : int
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.AbstractSlot(slotSig = SynValSig(trivia = { LeadingKeyword = SynLeadingKeyword.AbstractMember(mAbstract, mMember) }))
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 12) mAbstract
+        assertRange (3, 13) (3, 19) mMember
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``static member keyword`` () =
+    let parseResults = getParseResults """
+type X =
+    static member Y : int = 1
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.Member(memberDefn = SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.StaticMember(mStatic, mMember) }))
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 10) mStatic
+        assertRange (3, 11) (3, 17) mMember
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``static member val keyword`` () =
+    let parseResults = getParseResults """
+type X =
+    static member val Y : int = 1
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.AutoProperty(trivia = { LeadingKeyword = SynLeadingKeyword.StaticMemberVal(mStatic, mMember, mVal) })
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 10) mStatic
+        assertRange (3, 11) (3, 17) mMember
+        assertRange (3, 18) (3, 21) mVal
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``static abstract keyword`` () =
+    let parseResults = getParseResults """
+type X =
+    static abstract Y : int -> int
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.AbstractSlot(slotSig = SynValSig(trivia = { LeadingKeyword = SynLeadingKeyword.StaticAbstract(mStatic, mAbstract) }))
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 10) mStatic
+        assertRange (3, 11) (3, 19) mAbstract
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``static abstract member keyword`` () =
+    let parseResults = getParseResults """
+type X =
+    static abstract member Y : int -> int
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.AbstractSlot(slotSig = SynValSig(trivia = {
+                                LeadingKeyword = SynLeadingKeyword.StaticAbstractMember(mStatic, mAbstract, mMember)
+                            }))
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 10) mStatic
+        assertRange (3, 11) (3, 19) mAbstract
+        assertRange (3,20) (3, 26) mMember 
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``static val keyword`` () =
+    let parseResults = getParseResultsOfSignatureFile """
+namespace Meh
+
+type X =
+    static val Y : int -> int
+"""
+
+    match parseResults with
+    | ParsedInput.SigFile(ParsedSigFileInput(contents = [
+                SynModuleOrNamespaceSig(decls = [
+                    SynModuleSigDecl.Types(types = [
+                        SynTypeDefnSig(typeRepr = SynTypeDefnSigRepr.ObjectModel(memberSigs = [
+                            SynMemberSig.ValField(field =
+                                SynField(trivia = { LeadingKeyword = Some (SynLeadingKeyword.StaticVal(mStatic, mVal)) }))
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (5, 4) (5, 10) mStatic
+        assertRange (5, 11) (5, 14) mVal
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``default keyword`` () =
+    let parseResults = 
+        getParseResultsOfSignatureFile
+            """
+namespace X
+
+type Y =
+    default F : int
+"""
+
+    match parseResults with
+    | ParsedInput.SigFile (ParsedSigFileInput (contents = [ SynModuleOrNamespaceSig(decls = [
+        SynModuleSigDecl.Types(types =[
+            SynTypeDefnSig(typeRepr=SynTypeDefnSigRepr.ObjectModel(memberSigs=[
+                SynMemberSig.Member(memberSig = SynValSig(trivia = { LeadingKeyword = SynLeadingKeyword.Default mDefault }))
+            ]))
+        ])
+    ]) ])) ->
+        assertRange (5, 4) (5, 11) mDefault
+    | _ -> Assert.Fail "Could not get valid AST"
+
+[<Test>]
+let ``default val keyword`` () =
+    let ast = """
+type Foo =
+    default val A : int = 1
+"""
+                    |> getParseResults
+
+    match ast with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+        SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+            SynModuleDecl.Types ([
+                SynTypeDefn.SynTypeDefn (typeRepr = SynTypeDefnRepr.ObjectModel (members=[
+                    SynMemberDefn.AutoProperty(trivia = { LeadingKeyword = SynLeadingKeyword.DefaultVal(mDefault , mVal) })
+                ]))
+            ], _)
+        ])
+      ])) ->        
+        assertRange (3, 4) (3, 11) mDefault
+        assertRange (3, 12) (3, 15) mVal
+    | _ ->
+        Assert.Fail "Could not get valid AST"
+
+[<Test>]
+let ``val keyword`` () =
+    let parseResults = 
+        getParseResultsOfSignatureFile
+            """
+namespace X
+
+type Y =
+    val F : int
+"""
+
+    match parseResults with
+    | ParsedInput.SigFile (ParsedSigFileInput (contents = [ SynModuleOrNamespaceSig(decls = [
+        SynModuleSigDecl.Types(types =[
+            SynTypeDefnSig(typeRepr=SynTypeDefnSigRepr.ObjectModel(memberSigs=[
+                SynMemberSig.ValField(field = SynField(trivia = { LeadingKeyword = Some (SynLeadingKeyword.Val mVal) }))
+            ]))
+        ])
+    ]) ])) ->
+        assertRange (5, 4) (5, 7) mVal
+    | _ -> Assert.Fail "Could not get valid AST"
+
+[<Test>]
+let ``new keyword`` () =
+    let parseResults = getParseResults """
+type Y() =
+    new (message:string) = Y()
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.ImplicitCtor _
+                            SynMemberDefn.Member(memberDefn = SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.New mNew }))
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 7) mNew
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let ``synthetic keyword`` () =
+    let parseResults =
+        getParseResults """
+{ new ISomething with
+    a = () }
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Expr(expr =
+                        SynExpr.ObjExpr(bindings = [
+                            SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.Synthetic })
+                        ])
+                    )
+                ])
+            ])) ->
+        Assert.Pass()
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let `` static let keyword`` () =
+    let parseResults =
+        getParseResults """
+type X =
+    static let PI = 3.14
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.LetBindings(bindings = [
+                                SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.StaticLet(mStatic, mLet) })
+                            ])
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 10) mStatic
+        assertRange (3, 11) (3, 14) mLet
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let `` static let rec keyword`` () =
+    let parseResults =
+        getParseResults """
+type X =
+    static let rec forever () = forever()
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.LetBindings(bindings = [
+                                SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.StaticLetRec(mStatic, mLet, mRec) })
+                            ])
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 10) mStatic
+        assertRange (3, 11) (3, 14) mLet
+        assertRange (3, 15) (3, 18) mRec
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let `` do keyword`` () =
+    let parseResults =
+        getParseResults """
+type X =
+    do ()
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.LetBindings(bindings = [
+                                SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.Do(mDo) })
+                            ])
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 6) mDo
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
+
+[<Test>]
+let `` do static keyword`` () =
+    let parseResults =
+        getParseResults """
+type X =
+    static do ()
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
+                SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+                    SynModuleDecl.Types(typeDefns = [
+                        SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [
+                            SynMemberDefn.LetBindings(bindings = [
+                                SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.StaticDo(mStatic, mDo) })
+                            ])
+                        ]))
+                    ])
+                ])
+            ])) ->
+        assertRange (3, 4) (3, 10) mStatic
+        assertRange (3, 11) (3, 13) mDo
+    | _ -> Assert.Fail $"Could not get valid AST, got {parseResults}"
diff --git a/tests/service/SyntaxTreeTests/MemberFlagTests.fs b/tests/service/SyntaxTreeTests/MemberFlagTests.fs
index c29aad29300..c1c55b3a07c 100644
--- a/tests/service/SyntaxTreeTests/MemberFlagTests.fs
+++ b/tests/service/SyntaxTreeTests/MemberFlagTests.fs
@@ -2,6 +2,7 @@ module FSharp.Compiler.Service.Tests.SyntaxTreeTests.MemberFlagTestsTests
 
 open FSharp.Compiler.Service.Tests.Common
 open FSharp.Compiler.Syntax
+open FSharp.Compiler.SyntaxTrivia
 open NUnit.Framework
 
 
@@ -25,14 +26,12 @@ type Y =
     | ParsedInput.SigFile (ParsedSigFileInput (contents = [ SynModuleOrNamespaceSig(decls = [
         SynModuleSigDecl.Types(types =[
             SynTypeDefnSig(typeRepr=SynTypeDefnSigRepr.ObjectModel(memberSigs=[
-                SynMemberSig.Member(flags={ Trivia= { AbstractRange = Some mAbstract1 } })
-                SynMemberSig.Member(flags={ Trivia= { AbstractRange = Some mAbstract2
-                                                      MemberRange = Some mMember1 } })
-                SynMemberSig.Member(flags={ Trivia= { StaticRange = Some mStatic3
-                                                      MemberRange = Some mMember3 } })
-                SynMemberSig.Member(flags={ Trivia= { MemberRange = Some mMember4 } })
-                SynMemberSig.Member(flags={ Trivia= { OverrideRange = Some mOverride5 } })
-                SynMemberSig.Member(flags={ Trivia= { DefaultRange = Some mDefault6 } })
+                SynMemberSig.Member(memberSig = SynValSig(trivia = { LeadingKeyword = SynLeadingKeyword.Abstract mAbstract1 }))
+                SynMemberSig.Member(memberSig = SynValSig(trivia = { LeadingKeyword = SynLeadingKeyword.AbstractMember(mAbstract2, mMember1) }))
+                SynMemberSig.Member(memberSig = SynValSig(trivia = { LeadingKeyword = SynLeadingKeyword.StaticMember(mStatic3, mMember3) }))
+                SynMemberSig.Member(memberSig = SynValSig(trivia = { LeadingKeyword = SynLeadingKeyword.Member mMember4 }))
+                SynMemberSig.Member(memberSig = SynValSig(trivia = { LeadingKeyword = SynLeadingKeyword.Override mOverride5 }))
+                SynMemberSig.Member(memberSig = SynValSig(trivia = { LeadingKeyword = SynLeadingKeyword.Default mDefault6 }))
             ]))
         ])
     ]) ])) ->
@@ -60,9 +59,8 @@ type Foo =
         SynModuleOrNamespace.SynModuleOrNamespace(decls = [
             SynModuleDecl.Types ([
                 SynTypeDefn.SynTypeDefn (typeRepr = SynTypeDefnRepr.ObjectModel (members=[
-                    SynMemberDefn.AbstractSlot(flags={ Trivia = { AbstractRange = Some mAbstract1 } })
-                    SynMemberDefn.AbstractSlot(flags={ Trivia = { AbstractRange = Some mAbstract2
-                                                                  MemberRange = Some mMember2 } })
+                    SynMemberDefn.AbstractSlot(slotSig = SynValSig(trivia = { LeadingKeyword = SynLeadingKeyword.Abstract mAbstract1 }))
+                    SynMemberDefn.AbstractSlot(slotSig = SynValSig(trivia = { LeadingKeyword = SynLeadingKeyword.AbstractMember(mAbstract2, mMember2) }))
                 ]))
             ], _)
         ])
@@ -84,31 +82,36 @@ type Foo =
 """
                     |> getParseResults
 
+    let (|LeadingKeyword|_|) md =
+        match md with
+        | SynMemberDefn.AutoProperty(trivia = { LeadingKeyword = lk }) -> Some lk
+        | _ -> None
+    
     match ast with
     | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
         SynModuleOrNamespace.SynModuleOrNamespace(decls = [
             SynModuleDecl.Types ([
                 SynTypeDefn.SynTypeDefn (typeRepr = SynTypeDefnRepr.ObjectModel (members=[
-                    SynMemberDefn.AutoProperty(memberFlags= flags1)
-                    SynMemberDefn.AutoProperty(memberFlags= flags2)
-                    SynMemberDefn.AutoProperty(memberFlags= flags3)
-                    SynMemberDefn.AutoProperty(memberFlags= flags4)
+                    LeadingKeyword(SynLeadingKeyword.StaticMemberVal(mStatic1, mMember1, mVal1))
+                    LeadingKeyword(SynLeadingKeyword.MemberVal(mMember2, mVal2))
+                    LeadingKeyword(SynLeadingKeyword.OverrideVal(mOverride3, mVal3))
+                    LeadingKeyword(SynLeadingKeyword.DefaultVal(mDefault4, mVal4))
                 ]))
             ], _)
         ])
       ])) ->
-        let ({ Trivia = flagsTrivia1 } : SynMemberFlags) = flags1
-        assertRange (3, 4) (3, 10) flagsTrivia1.StaticRange.Value
-        assertRange (3, 11) (3, 17) flagsTrivia1.MemberRange.Value
+        assertRange (3, 4) (3, 10) mStatic1
+        assertRange (3, 11) (3, 17) mMember1
+        assertRange (3, 18) (3, 21) mVal1
 
-        let ({ Trivia = flagsTrivia2 } : SynMemberFlags) = flags2
-        assertRange (4, 4) (4, 10) flagsTrivia2.MemberRange.Value
+        assertRange (4, 4) (4, 10) mMember2
+        assertRange (4, 11) (4, 14) mVal2
         
-        let ({ Trivia = flagsTrivia3 } : SynMemberFlags) = flags3
-        assertRange (5, 4) (5, 12) flagsTrivia3.OverrideRange.Value
+        assertRange (5, 4) (5, 12) mOverride3
+        assertRange (5, 13) (5, 16) mVal3
         
-        let ({ Trivia = flagsTrivia4 } : SynMemberFlags) = flags4
-        assertRange (6, 4) (6, 11) flagsTrivia4.DefaultRange.Value
+        assertRange (6, 4) (6, 11) mDefault4
+        assertRange (6, 12) (6, 15) mVal4
     | _ ->
         Assert.Fail "Could not get valid AST"
 
@@ -123,16 +126,20 @@ type Foo =
 """
                     |> getParseResults
 
+    let (|LeadingKeyword|_|) md =
+        match md with
+        | SynMemberDefn.Member(memberDefn = SynBinding(trivia = { LeadingKeyword = lk })) -> Some lk
+        | _ -> None
+    
     match ast with
     | ParsedInput.ImplFile(ParsedImplFileInput(contents = [
         SynModuleOrNamespace.SynModuleOrNamespace(decls = [
             SynModuleDecl.Types ([
                 SynTypeDefn.SynTypeDefn (typeRepr = SynTypeDefnRepr.ObjectModel (members=[
-                    SynMemberDefn.Member(memberDefn=SynBinding(valData=SynValData(memberFlags=Some { Trivia = { StaticRange = Some mStatic1
-                                                                                                                MemberRange = Some mMember1 } })))
-                    SynMemberDefn.Member(memberDefn=SynBinding(valData=SynValData(memberFlags=Some { Trivia = { MemberRange = Some mMember2 } })))
-                    SynMemberDefn.Member(memberDefn=SynBinding(valData=SynValData(memberFlags=Some { Trivia = { OverrideRange = Some mOverride3 } })))
-                    SynMemberDefn.Member(memberDefn=SynBinding(valData=SynValData(memberFlags=Some { Trivia = { DefaultRange = Some mDefaultRange4 } })))
+                    LeadingKeyword(SynLeadingKeyword.StaticMember(mStatic1, mMember1))
+                    LeadingKeyword(SynLeadingKeyword.Member(mMember2))
+                    LeadingKeyword(SynLeadingKeyword.Override(mOverride3))
+                    LeadingKeyword(SynLeadingKeyword.Default mDefaultRange4)
                 ]))
             ], _)
         ])
@@ -163,11 +170,11 @@ let meh =
             SynModuleDecl.Let (bindings = [
                 SynBinding(expr=SynExpr.ObjExpr(
                     members=[
-                        SynMemberDefn.Member(memberDefn=SynBinding(valData=SynValData(memberFlags=Some { Trivia = { OverrideRange = Some mOverride1 } })))
-                        SynMemberDefn.Member(memberDefn=SynBinding(valData=SynValData(memberFlags=Some { Trivia = { MemberRange = Some mMember2 } })))
+                        SynMemberDefn.Member(memberDefn=SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.Override mOverride1 }))
+                        SynMemberDefn.Member(memberDefn=SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.Member mMember2 }))
                     ]
                     extraImpls=[ SynInterfaceImpl(members=[
-                        SynMemberDefn.Member(memberDefn=SynBinding(valData=SynValData(memberFlags=Some { Trivia = { MemberRange = Some mMember3 } })))
+                        SynMemberDefn.Member(memberDefn=SynBinding(trivia = { LeadingKeyword = SynLeadingKeyword.Member mMember3 }))
                     ]) ]))
             ])
       ]) ])) ->
diff --git a/tests/service/SyntaxTreeTests/MemberTests.fs b/tests/service/SyntaxTreeTests/MemberTests.fs
index 084af4bff85..24693fd12bc 100644
--- a/tests/service/SyntaxTreeTests/MemberTests.fs
+++ b/tests/service/SyntaxTreeTests/MemberTests.fs
@@ -19,7 +19,7 @@ type Person(name : string, age : int) =
     match parseResults with
     | ParsedInput.ImplFile (ParsedImplFileInput (contents = [ SynModuleOrNamespace.SynModuleOrNamespace(decls = [
         SynModuleDecl.Types(
-            typeDefns = [ SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [_ ; SynMemberDefn.AutoProperty(equalsRange = mEquals)])) ]
+            typeDefns = [ SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [_ ; SynMemberDefn.AutoProperty(trivia = { EqualsRange = Some mEquals })])) ]
         )
     ]) ])) ->
         assertRange (5, 20) (5, 21) mEquals
@@ -39,8 +39,8 @@ type Foo() =
     | ParsedInput.ImplFile (ParsedImplFileInput (contents = [ SynModuleOrNamespace.SynModuleOrNamespace(decls = [
         SynModuleDecl.Types(
             typeDefns = [ SynTypeDefn(typeRepr = SynTypeDefnRepr.ObjectModel(members = [_
-                                                                                        SynMemberDefn.AutoProperty(withKeyword=Some mWith)
-                                                                                        SynMemberDefn.AutoProperty(withKeyword=None)])) ]
+                                                                                        SynMemberDefn.AutoProperty(trivia = { WithKeyword = Some mWith })
+                                                                                        SynMemberDefn.AutoProperty(trivia = { WithKeyword = None })])) ]
         )
     ]) ])) ->
         assertRange (3, 39) (3, 43) mWith
diff --git a/tests/service/SyntaxTreeTests/SignatureTypeTests.fs b/tests/service/SyntaxTreeTests/SignatureTypeTests.fs
index 7532e835ca2..8d1d94d450f 100644
--- a/tests/service/SyntaxTreeTests/SignatureTypeTests.fs
+++ b/tests/service/SyntaxTreeTests/SignatureTypeTests.fs
@@ -2,6 +2,7 @@ module FSharp.Compiler.Service.Tests.SyntaxTreeTests.SignatureTypeTests
 
 open FSharp.Compiler.Service.Tests.Common
 open FSharp.Compiler.Syntax
+open FSharp.Compiler.SyntaxTrivia
 open NUnit.Framework
 
 [<Test>]
@@ -378,7 +379,7 @@ val a : int
     match parseResults with
     | ParsedInput.SigFile (ParsedSigFileInput (contents=[
         SynModuleOrNamespaceSig(decls=[
-            SynModuleSigDecl.Val(valSig = SynValSig(trivia = { ValKeyword = Some mVal }))
+            SynModuleSigDecl.Val(valSig = SynValSig(trivia = { LeadingKeyword = SynLeadingKeyword.Val mVal }))
         ] ) ])) ->
         assertRange (6, 0) (6, 3) mVal
     | _ -> Assert.Fail "Could not get valid AST"
diff --git a/tests/service/TreeVisitorTests.fs b/tests/service/TreeVisitorTests.fs
index f9a56bdd16c..9bcfa47796a 100644
--- a/tests/service/TreeVisitorTests.fs
+++ b/tests/service/TreeVisitorTests.fs
@@ -31,7 +31,7 @@ let ``Visit record definition test`` () =
     let parseTree = parseSourceCode("C:\\test.fs", source)
 
     match SyntaxTraversal.Traverse(pos0, parseTree, visitor) with
-    | Some [ SynField (_, _, Some id1, _, _, _, _, _); SynField (_, _, Some id2, _, _, _, _, _) ] when id1.idText = "A" && id2.idText = "B" -> ()
+    | Some [ SynField (idOpt = Some id1); SynField (idOpt = Some id2) ] when id1.idText = "A" && id2.idText = "B" -> ()
     | _ -> failwith "Did not visit record definition"
 
 [<Test>]

From 5d69143fbe992d8fa33d5b83d5fdd5f4ed7bb4fc Mon Sep 17 00:00:00 2001
From: "Kevin Ransom (msft)" <codecutter@hotmail.com>
Date: Thu, 13 Oct 2022 09:43:32 -0700
Subject: [PATCH 7/8] update versions (#14099)

---
 eng/Versions.props | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/eng/Versions.props b/eng/Versions.props
index 0054e122a6a..3670270fcc9 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -15,7 +15,7 @@
     <!-- F# Version components -->
     <FSMajorVersion>6</FSMajorVersion>
     <FSMinorVersion>0</FSMinorVersion>
-    <FSBuildVersion>6</FSBuildVersion>
+    <FSBuildVersion>7</FSBuildVersion>
     <FSRevisionVersion>0</FSRevisionVersion>
     <!-- -->
     <!-- F# Language version -->
@@ -32,14 +32,14 @@
     <!-- FSharp.Compiler.Service version -->
     <FCSMajorVersion>41</FCSMajorVersion>
     <FCSMinorVersion>0</FCSMinorVersion>
-    <FCSBuildVersion>6</FCSBuildVersion>
+    <FCSBuildVersion>7</FCSBuildVersion>
     <FCSRevisionVersion>$(FSRevisionVersion)</FCSRevisionVersion>
     <FSharpCompilerServicePackageVersion>$(FCSMajorVersion).$(FCSMinorVersion).$(FCSBuildVersion)</FSharpCompilerServicePackageVersion>
     <FSharpCompilerServiceVersion>$(FCSMajorVersion).$(FCSMinorVersion).$(FCSBuildVersion).$(FCSRevisionVersion)</FSharpCompilerServiceVersion>
     <FSharpCompilerServiceReleaseNotesVersion>$(FCSMajorVersion)$(FCSMinorVersion)$(FCSBuildVersion)</FSharpCompilerServiceReleaseNotesVersion>
     <!-- -->
     <!-- The current published nuget package -->
-    <FSharpCoreShippedPackageVersionValue>6.0.3</FSharpCoreShippedPackageVersionValue>
+    <FSharpCoreShippedPackageVersionValue>6.0.6</FSharpCoreShippedPackageVersionValue>
     <!-- -->
     <!-- The pattern for specifying the preview package -->
     <FSharpCorePreviewPackageVersionValue>$(FSCorePackageVersionValue)-$(PreReleaseVersionLabel).*</FSharpCorePreviewPackageVersionValue>
@@ -47,7 +47,7 @@
     <!-- FSharp tools for Visual Studio version number -->
     <FSToolsMajorVersion>12</FSToolsMajorVersion>
     <FSToolsMinorVersion>0</FSToolsMinorVersion>
-    <FSToolsBuildVersion>4</FSToolsBuildVersion>
+    <FSToolsBuildVersion>5</FSToolsBuildVersion>
     <FSToolsRevisionVersion>$(FSRevisionVersion)</FSToolsRevisionVersion>
     <FSProductVersionPrefix>$(FSToolsMajorVersion).$(FSToolsMinorVersion).$(FSToolsBuildVersion)</FSProductVersionPrefix>
     <FSProductVersionReleaseNotesVersion>$(FSToolsMajorVersion)-$(FSToolsMinorVersion)-$(FSToolsBuildVersion)</FSProductVersionReleaseNotesVersion>

From 823f7d5c55245954f468f1b239a189c3b88af34b Mon Sep 17 00:00:00 2001
From: Theodore Tsirpanis <teo@tsirpanis.gr>
Date: Fri, 14 Oct 2022 12:24:05 +0300
Subject: [PATCH 8/8] Use MSBuild's logging facilities instead of writing to
 console. (#13896)

* Use MSBuild's logging facilities instead of writing to console.

* Changing usage of WriteCodeFragment in tests

* Applying cleaner formatting

Co-authored-by: Tomas Grosup <tomasgrosup@microsoft.com>
---
 src/FSharp.Build/FSharpEmbedResXSource.fs     |  44 +++----
 src/FSharp.Build/FSharpEmbedResourceText.fs   |  89 +++++++------
 src/FSharp.Build/SubstituteText.fs            | 118 ++++++++----------
 src/FSharp.Build/WriteCodeFragment.fs         | 113 ++++++++---------
 .../WriteCodeFragmentTests.fs                 |   6 +-
 5 files changed, 177 insertions(+), 193 deletions(-)

diff --git a/src/FSharp.Build/FSharpEmbedResXSource.fs b/src/FSharp.Build/FSharpEmbedResXSource.fs
index 4b34660b2a8..29a2ceefd19 100644
--- a/src/FSharp.Build/FSharpEmbedResXSource.fs
+++ b/src/FSharp.Build/FSharpEmbedResXSource.fs
@@ -10,14 +10,20 @@ open System.Xml.Linq
 open Microsoft.Build.Framework
 open Microsoft.Build.Utilities
 
-type FSharpEmbedResXSource() =
-    let mutable _buildEngine: IBuildEngine MaybeNull = null
-    let mutable _hostObject: ITaskHost MaybeNull = null
+type FSharpEmbedResXSource() as this =
+    inherit Task()
     let mutable _embeddedText: ITaskItem[] = [||]
     let mutable _generatedSource: ITaskItem[] = [||]
     let mutable _outputPath: string = ""
     let mutable _targetFramework: string = ""
 
+    let failTask fmt =
+        Printf.ksprintf
+            (fun msg ->
+                this.Log.LogError msg
+                raise TaskFailed)
+            fmt
+
     let boilerplate =
         @"// <auto-generated>
 
@@ -36,7 +42,7 @@ module internal {1} =
 
     let generateSource (resx: string) (fullModuleName: string) (generateLegacy: bool) (generateLiteral: bool) =
         try
-            let printMessage = printfn "FSharpEmbedResXSource: %s"
+            let printMessage fmt = Printf.ksprintf this.Log.LogMessage fmt
             let justFileName = Path.GetFileNameWithoutExtension(resx)
             let sourcePath = Path.Combine(_outputPath, justFileName + ".fs")
 
@@ -46,7 +52,7 @@ module internal {1} =
                 && File.Exists(sourcePath)
                 && File.GetLastWriteTimeUtc(resx) <= File.GetLastWriteTimeUtc(sourcePath)
             then
-                printMessage (sprintf "Skipping generation: '%s' since it is up-to-date." sourcePath)
+                printMessage "Skipping generation: '%s' since it is up-to-date." sourcePath
                 Some(sourcePath)
             else
                 let namespaceName, moduleName =
@@ -63,7 +69,7 @@ module internal {1} =
                         || _targetFramework.StartsWith("netcoreapp1.")
                     )
 
-                printMessage (sprintf "Generating code for target framework %s" _targetFramework)
+                printMessage "Generating code for target framework %s" _targetFramework
 
                 let sb =
                     StringBuilder()
@@ -72,7 +78,7 @@ module internal {1} =
                 if generateGetObject then
                     sb.AppendLine(boilerplateGetObject) |> ignore
 
-                printMessage <| sprintf "Generating: %s" sourcePath
+                printMessage "Generating: %s" sourcePath
 
                 let body =
                     let xname = XName.op_Implicit
@@ -82,12 +88,12 @@ module internal {1} =
                         (fun (sb: StringBuilder) (node: XElement) ->
                             let name =
                                 match node.Attribute(xname "name") with
-                                | null -> failwith (sprintf "Missing resource name on element '%s'" (node.ToString()))
+                                | null -> failTask "Missing resource name on element '%O'" node
                                 | attr -> attr.Value
 
                             let docComment =
                                 match node.Elements(xname "value").FirstOrDefault() with
-                                | null -> failwith <| sprintf "Missing resource value for '%s'" name
+                                | null -> failTask "Missing resource value for '%s'" name
                                 | element -> element.Value.Trim()
 
                             let identifier =
@@ -118,7 +124,7 @@ module internal {1} =
                         sb
 
                 File.WriteAllText(sourcePath, body.ToString())
-                printMessage <| sprintf "Done: %s" sourcePath
+                printMessage "Done: %s" sourcePath
                 Some(sourcePath)
         with e ->
             printf "An exception occurred when processing '%s'\n%s" resx (e.ToString())
@@ -141,16 +147,8 @@ module internal {1} =
     [<Output>]
     member _.GeneratedSource = _generatedSource
 
-    interface ITask with
-        member _.BuildEngine
-            with get () = _buildEngine
-            and set (value) = _buildEngine <- value
-
-        member _.HostObject
-            with get () = _hostObject
-            and set (value) = _hostObject <- value
-
-        member this.Execute() =
+    override this.Execute() =
+        try
             let getBooleanMetadata (metadataName: string) (defaultValue: bool) (item: ITaskItem) =
                 match item.GetMetadata(metadataName) with
                 | value when String.IsNullOrWhiteSpace(value) -> defaultValue
@@ -158,7 +156,7 @@ module internal {1} =
                     match value.ToLowerInvariant() with
                     | "true" -> true
                     | "false" -> false
-                    | _ -> failwith (sprintf "Expected boolean value for '%s' found '%s'" metadataName value)
+                    | _ -> failTask "Expected boolean value for '%s' found '%s'" metadataName value
 
             let mutable success = true
 
@@ -181,4 +179,6 @@ module internal {1} =
                 |]
 
             _generatedSource <- generatedSource
-            success
+            success && not this.Log.HasLoggedErrors
+        with TaskFailed ->
+            false
diff --git a/src/FSharp.Build/FSharpEmbedResourceText.fs b/src/FSharp.Build/FSharpEmbedResourceText.fs
index d8a3848ba27..71dbc791a0c 100644
--- a/src/FSharp.Build/FSharpEmbedResourceText.fs
+++ b/src/FSharp.Build/FSharpEmbedResourceText.fs
@@ -6,24 +6,32 @@ open System.IO
 open Microsoft.Build.Framework
 open Microsoft.Build.Utilities
 
-type FSharpEmbedResourceText() =
-    let mutable _buildEngine: IBuildEngine MaybeNull = null
-    let mutable _hostObject: ITaskHost MaybeNull = null
+/// A special exception that when thrown signifies that
+/// the task should end with failure. It is assumed that
+/// the task has already emitted the error message.
+exception TaskFailed
+
+type FSharpEmbedResourceText() as this =
+    inherit Task()
     let mutable _embeddedText: ITaskItem[] = [||]
     let mutable _generatedSource: ITaskItem[] = [||]
     let mutable _generatedResx: ITaskItem[] = [||]
     let mutable _outputPath: string = ""
 
     let PrintErr (fileName, line, msg) =
-        printfn "%s(%d): error : %s" fileName line msg
+        this.Log.LogError(null, null, null, fileName, line, 0, 0, 0, msg, Array.empty)
 
     let Err (fileName, line, msg) =
         PrintErr(fileName, line, msg)
-        printfn "Note that the syntax of each line is one of these three alternatives:"
-        printfn "# comment"
-        printfn "ident,\"string\""
-        printfn "errNum,ident,\"string\""
-        failwith (sprintf "there were errors in the file '%s'" fileName)
+
+        let hint =
+            "Note that the syntax of each line is one of these three alternatives:
+# comment
+ident,\"string\"
+errNum,ident,\"string\""
+
+        this.Log.LogMessage(MessageImportance.High, hint)
+        raise TaskFailed
 
     let xmlBoilerPlateString =
         @"<?xml version=""1.0"" encoding=""utf-8""?>
@@ -192,7 +200,7 @@ type FSharpEmbedResourceText() =
         if s.StartsWith "\"" && s.EndsWith "\"" then
             s.Substring(1, s.Length - 2)
         else
-            failwith "error message string should be quoted"
+            Err(null, 0, "error message string should be quoted")
 
     let ParseLine fileName lineNum (txt: string) =
         let mutable errNum = None
@@ -361,8 +369,7 @@ open Printf
 
     let generateResxAndSource (fileName: string) =
         try
-            let printMessage message =
-                printfn "FSharpEmbedResourceText: %s" message
+            let printMessage fmt = Printf.ksprintf this.Log.LogMessage fmt
 
             let justFileName = Path.GetFileNameWithoutExtension(fileName) // .txt
 
@@ -391,35 +398,33 @@ open Printf
                 && (File.GetLastWriteTimeUtc(fileName) <= File.GetLastWriteTimeUtc(outXmlFileName))
 
             if condition5 then
-                printMessage (sprintf "Skipping generation of %s and %s from %s since up-to-date" outFileName outXmlFileName fileName)
+                printMessage "Skipping generation of %s and %s from %s since up-to-date" outFileName outXmlFileName fileName
 
                 Some(fileName, outFileName, outXmlFileName)
             else
-                printMessage (
-                    sprintf
-                        "Generating %s and %s from %s, because condition %d is false, see FSharpEmbedResourceText.fs in the F# source"
-                        outFileName
-                        outXmlFileName
-                        fileName
-                        (if not condition1 then 1
-                         elif not condition2 then 2
-                         elif not condition3 then 3
-                         elif not condition4 then 4
-                         else 5)
-                )
-
-                printMessage (sprintf "Reading %s" fileName)
+                printMessage
+                    "Generating %s and %s from %s, because condition %d is false, see FSharpEmbedResourceText.fs in the F# source"
+                    outFileName
+                    outXmlFileName
+                    fileName
+                    (if not condition1 then 1
+                     elif not condition2 then 2
+                     elif not condition3 then 3
+                     elif not condition4 then 4
+                     else 5)
+
+                printMessage "Reading %s" fileName
 
                 let lines =
                     File.ReadAllLines(fileName)
                     |> Array.mapi (fun i s -> i, s) // keep line numbers
                     |> Array.filter (fun (i, s) -> not (s.StartsWith "#")) // filter out comments
 
-                printMessage (sprintf "Parsing %s" fileName)
+                printMessage "Parsing %s" fileName
                 let stringInfos = lines |> Array.map (fun (i, s) -> ParseLine fileName i s)
                 // now we have array of (lineNum, ident, str, holes, netFormatString)  // str has %d, netFormatString has {0}
 
-                printMessage (sprintf "Validating %s" fileName)
+                printMessage "Validating %s" fileName
                 // validate that all the idents are unique
                 let allIdents = new System.Collections.Generic.Dictionary<string, int>()
 
@@ -436,7 +441,7 @@ open Printf
 
                     allIdents.Add(ident, line)
 
-                printMessage (sprintf "Validating uniqueness of %s" fileName)
+                printMessage "Validating uniqueness of %s" fileName
                 // validate that all the strings themselves are unique
                 let allStrs = new System.Collections.Generic.Dictionary<string, (int * string)>()
 
@@ -456,7 +461,7 @@ open Printf
 
                     allStrs.Add(str, (line, ident))
 
-                printMessage (sprintf "Generating %s" outFileName)
+                printMessage "Generating %s" outFileName
                 use outStream = File.Create outFileName
                 use out = new StreamWriter(outStream)
                 fprintfn out "// This is a generated file; the original input is '%s'" fileName
@@ -466,7 +471,7 @@ open Printf
                 let theResourceName = justFileName
                 fprintfn out "%s" (StringBoilerPlate theResourceName)
 
-                printMessage (sprintf "Generating resource methods for %s" outFileName)
+                printMessage "Generating resource methods for %s" outFileName
                 // gen each resource method
                 stringInfos
                 |> Seq.iter (fun (lineNum, (optErrNum, ident), str, holes, netFormatString) ->
@@ -520,7 +525,7 @@ open Printf
                         justPercentsFromFormatString
                         (actualArgs.ToString()))
 
-                printMessage (sprintf "Generating .resx for %s" outFileName)
+                printMessage "Generating .resx for %s" outFileName
                 fprintfn out ""
                 // gen validation method
                 fprintfn out "    /// Call this method once to validate that all known resources are valid; throws if not"
@@ -548,7 +553,7 @@ open Printf
 
                 use outXmlStream = File.Create outXmlFileName
                 xd.Save outXmlStream
-                printMessage (sprintf "Done %s" outFileName)
+                printMessage "Done %s" outFileName
                 Some(fileName, outFileName, outXmlFileName)
         with e ->
             PrintErr(fileName, 0, sprintf "An exception occurred when processing '%s'\n%s" fileName (e.ToString()))
@@ -570,17 +575,9 @@ open Printf
     [<Output>]
     member _.GeneratedResx = _generatedResx
 
-    interface ITask with
-        member _.BuildEngine
-            with get () = _buildEngine
-            and set (value) = _buildEngine <- value
-
-        member _.HostObject
-            with get () = _hostObject
-            and set (value) = _hostObject <- value
-
-        member this.Execute() =
+    override this.Execute() =
 
+        try
             let generatedFiles =
                 this.EmbeddedText
                 |> Array.choose (fun item -> generateResxAndSource item.ItemSpec)
@@ -609,4 +606,6 @@ open Printf
 
             _generatedSource <- generatedSource
             _generatedResx <- generatedResx
-            generatedResult
+            generatedResult && not this.Log.HasLoggedErrors
+        with TaskFailed ->
+            false
diff --git a/src/FSharp.Build/SubstituteText.fs b/src/FSharp.Build/SubstituteText.fs
index 0f036da0a86..2e4950a62b3 100644
--- a/src/FSharp.Build/SubstituteText.fs
+++ b/src/FSharp.Build/SubstituteText.fs
@@ -5,11 +5,10 @@ namespace FSharp.Build
 open System
 open System.IO
 open Microsoft.Build.Framework
+open Microsoft.Build.Utilities
 
 type SubstituteText() =
-
-    let mutable _buildEngine: IBuildEngine MaybeNull = null
-    let mutable _hostObject: ITaskHost MaybeNull = null
+    inherit Task()
 
     let mutable copiedFiles = new ResizeArray<ITaskItem>()
     let mutable embeddedResources: ITaskItem[] = [||]
@@ -22,74 +21,65 @@ type SubstituteText() =
     [<Output>]
     member _.CopiedFiles = copiedFiles.ToArray()
 
-    interface ITask with
-        member _.BuildEngine
-            with get () = _buildEngine
-            and set (value) = _buildEngine <- value
-
-        member _.HostObject
-            with get () = _hostObject
-            and set (value) = _hostObject <- value
-
-        member _.Execute() =
-            copiedFiles.Clear()
-
-            if not (isNull embeddedResources) then
-                for item in embeddedResources do
-                    // Update ITaskItem metadata to point to new location
-                    let sourcePath = item.GetMetadata("FullPath")
-
-                    let pattern1 = item.GetMetadata("Pattern1")
-                    let pattern2 = item.GetMetadata("Pattern2")
-
-                    // Is there any replacement to do?
-                    if not (String.IsNullOrWhiteSpace(pattern1) && String.IsNullOrWhiteSpace(pattern2)) then
-                        if not (String.IsNullOrWhiteSpace(sourcePath)) then
-                            try
-                                let getTargetPathFrom key =
-                                    let md = item.GetMetadata(key)
-                                    let path = Path.GetDirectoryName(md)
-                                    let fileName = Path.GetFileName(md)
-                                    let target = Path.Combine(path, @"..\resources", fileName)
+    override _.Execute() =
+        copiedFiles.Clear()
+
+        if not (isNull embeddedResources) then
+            for item in embeddedResources do
+                // Update ITaskItem metadata to point to new location
+                let sourcePath = item.GetMetadata("FullPath")
+
+                let pattern1 = item.GetMetadata("Pattern1")
+                let pattern2 = item.GetMetadata("Pattern2")
+
+                // Is there any replacement to do?
+                if not (String.IsNullOrWhiteSpace(pattern1) && String.IsNullOrWhiteSpace(pattern2)) then
+                    if not (String.IsNullOrWhiteSpace(sourcePath)) then
+                        try
+                            let getTargetPathFrom key =
+                                let md = item.GetMetadata(key)
+                                let path = Path.GetDirectoryName(md)
+                                let fileName = Path.GetFileName(md)
+                                let target = Path.Combine(path, @"..\resources", fileName)
+                                target
+
+                            // Copy from the location specified in Identity
+                            let sourcePath = item.GetMetadata("Identity")
+
+                            // Copy to the location specified in TargetPath unless no TargetPath is provided, then use Identity
+                            let targetPath =
+                                let identityPath = getTargetPathFrom "Identity"
+                                let intermediateTargetPath = item.GetMetadata("IntermediateTargetPath")
+
+                                if not (String.IsNullOrWhiteSpace(intermediateTargetPath)) then
+                                    let fileName = Path.GetFileName(identityPath)
+                                    let target = Path.Combine(intermediateTargetPath, fileName)
                                     target
+                                else
+                                    identityPath
 
-                                // Copy from the location specified in Identity
-                                let sourcePath = item.GetMetadata("Identity")
-
-                                // Copy to the location specified in TargetPath unless no TargetPath is provided, then use Identity
-                                let targetPath =
-                                    let identityPath = getTargetPathFrom "Identity"
-                                    let intermediateTargetPath = item.GetMetadata("IntermediateTargetPath")
-
-                                    if not (String.IsNullOrWhiteSpace(intermediateTargetPath)) then
-                                        let fileName = Path.GetFileName(identityPath)
-                                        let target = Path.Combine(intermediateTargetPath, fileName)
-                                        target
-                                    else
-                                        identityPath
-
-                                item.ItemSpec <- targetPath
+                            item.ItemSpec <- targetPath
 
-                                // Transform file
-                                let mutable contents = File.ReadAllText(sourcePath)
+                            // Transform file
+                            let mutable contents = File.ReadAllText(sourcePath)
 
-                                if not (String.IsNullOrWhiteSpace(pattern1)) then
-                                    let replacement = item.GetMetadata("Replacement1")
-                                    contents <- contents.Replace(pattern1, replacement)
+                            if not (String.IsNullOrWhiteSpace(pattern1)) then
+                                let replacement = item.GetMetadata("Replacement1")
+                                contents <- contents.Replace(pattern1, replacement)
 
-                                if not (String.IsNullOrWhiteSpace(pattern2)) then
-                                    let replacement = item.GetMetadata("Replacement2")
-                                    contents <- contents.Replace(pattern2, replacement)
+                            if not (String.IsNullOrWhiteSpace(pattern2)) then
+                                let replacement = item.GetMetadata("Replacement2")
+                                contents <- contents.Replace(pattern2, replacement)
 
-                                let directory = Path.GetDirectoryName(targetPath)
+                            let directory = Path.GetDirectoryName(targetPath)
 
-                                if not (Directory.Exists(directory)) then
-                                    Directory.CreateDirectory(directory) |> ignore
+                            if not (Directory.Exists(directory)) then
+                                Directory.CreateDirectory(directory) |> ignore
 
-                                File.WriteAllText(targetPath, contents)
-                            with _ ->
-                                ()
+                            File.WriteAllText(targetPath, contents)
+                        with _ ->
+                            ()
 
-                    copiedFiles.Add(item)
+                copiedFiles.Add(item)
 
-            true
+        true
diff --git a/src/FSharp.Build/WriteCodeFragment.fs b/src/FSharp.Build/WriteCodeFragment.fs
index ab390ae4a59..7df19fad327 100644
--- a/src/FSharp.Build/WriteCodeFragment.fs
+++ b/src/FSharp.Build/WriteCodeFragment.fs
@@ -9,14 +9,20 @@ open System.Text
 open Microsoft.Build.Framework
 open Microsoft.Build.Utilities
 
-type WriteCodeFragment() =
-    let mutable _buildEngine: IBuildEngine MaybeNull = null
-    let mutable _hostObject: ITaskHost MaybeNull = null
+type WriteCodeFragment() as this =
+    inherit Task()
     let mutable _outputDirectory: ITaskItem MaybeNull = null
     let mutable _outputFile: ITaskItem MaybeNull = null
     let mutable _language: string = ""
     let mutable _assemblyAttributes: ITaskItem[] = [||]
 
+    let failTask fmt =
+        Printf.ksprintf
+            (fun msg ->
+                this.Log.LogError msg
+                raise TaskFailed)
+            fmt
+
     static let escapeString (str: string) =
         let sb =
             str.ToCharArray()
@@ -37,7 +43,7 @@ type WriteCodeFragment() =
 
         sb.Append("\"").ToString()
 
-    static member GenerateAttribute(item: ITaskItem, language: string) =
+    member _.GenerateAttribute(item: ITaskItem, language: string) =
         let attributeName = item.ItemSpec
 
         let args =
@@ -70,7 +76,7 @@ type WriteCodeFragment() =
 
                     match Int32.TryParse indexString with
                     | (true, index) -> (index, value)
-                    | (false, _) -> failwith (sprintf "Unable to parse '%s' as an index" indexString))
+                    | (false, _) -> failTask "Unable to parse '%s' as an index" indexString)
                 |> List.sortBy fst
             // assign ordered parameters to array
             let orderedParametersArray =
@@ -96,7 +102,7 @@ type WriteCodeFragment() =
         | "f#" -> sprintf "[<assembly: %s(%s)>]" attributeName args
         | "c#" -> sprintf "[assembly: %s(%s)]" attributeName args
         | "vb" -> sprintf "<Assembly: %s(%s)>" attributeName args
-        | _ -> failwith "Language name must be one of F#, C# or VB"
+        | _ -> failTask "Language name must be one of F#, C# or VB"
 
     // adding this property to maintain API equivalence with the MSBuild task
     member _.Language
@@ -116,56 +122,45 @@ type WriteCodeFragment() =
         with get () = _outputFile
         and set (value) = _outputFile <- value
 
-    interface ITask with
-        member _.BuildEngine
-            with get () = _buildEngine
-            and set (value) = _buildEngine <- value
-
-        member _.HostObject
-            with get () = _hostObject
-            and set (value) = _hostObject <- value
-
-        member _.Execute() =
-            try
-                match _outputFile with
-                | Null -> failwith "Output location must be specified"
-                | NonNull outputFile ->
-                    let boilerplate =
-                        match _language.ToLowerInvariant() with
-                        | "f#" ->
-                            "// <auto-generated>\n//     Generated by the FSharp WriteCodeFragment class.\n// </auto-generated>\nnamespace FSharp\n\nopen System\nopen System.Reflection\n"
-                        | "c#" ->
-                            "// <auto-generated>\n//     Generated by the FSharp WriteCodeFragment class.\n// </auto-generated>\n\nusing System;\nusing System.Reflection;"
-                        | "vb" ->
-                            "'------------------------------------------------------------------------------\n' <auto-generated>\n'     Generated by the FSharp WriteCodeFragment class.\n' </auto-generated>\n'------------------------------------------------------------------------------\n\nOption Strict Off\nOption Explicit On\n\nImports System\nImports System.Reflection"
-                        | _ -> failwith "Language name must be one of F#, C# or VB"
-
-                    let sb = StringBuilder().AppendLine(boilerplate).AppendLine()
-
-                    let code =
-                        (sb, _assemblyAttributes)
-                        ||> Array.fold (fun (sb: StringBuilder) (item: ITaskItem) ->
-                            sb.AppendLine(WriteCodeFragment.GenerateAttribute(item, _language.ToLowerInvariant())))
-
-                    if _language.ToLowerInvariant() = "f#" then
-                        code.AppendLine("do()") |> ignore
-
-                    let fileName = outputFile.ItemSpec
-
-                    let outputFileItem =
-                        match _outputDirectory with
-                        | Null -> outputFile
-                        | NonNull outputDirectory ->
-                            if Path.IsPathRooted(fileName) then
-                                outputFile
-                            else
-                                TaskItem(Path.Combine(outputDirectory.ItemSpec, fileName)) :> ITaskItem
-
-                    let codeText = code.ToString()
-                    File.WriteAllText(fileName, codeText)
-                    _outputFile <- outputFileItem
-                    true
-
-            with e ->
-                printf "Error writing code fragment: %s" (e.ToString())
-                false
+    override this.Execute() =
+        try
+            match _outputFile with
+            | Null -> failTask "Output location must be specified"
+            | NonNull outputFile ->
+                let boilerplate =
+                    match _language.ToLowerInvariant() with
+                    | "f#" ->
+                        "// <auto-generated>\n//     Generated by the FSharp WriteCodeFragment class.\n// </auto-generated>\nnamespace FSharp\n\nopen System\nopen System.Reflection\n"
+                    | "c#" ->
+                        "// <auto-generated>\n//     Generated by the FSharp WriteCodeFragment class.\n// </auto-generated>\n\nusing System;\nusing System.Reflection;"
+                    | "vb" ->
+                        "'------------------------------------------------------------------------------\n' <auto-generated>\n'     Generated by the FSharp WriteCodeFragment class.\n' </auto-generated>\n'------------------------------------------------------------------------------\n\nOption Strict Off\nOption Explicit On\n\nImports System\nImports System.Reflection"
+                    | _ -> failTask "Language name must be one of F#, C# or VB"
+
+                let sb = StringBuilder().AppendLine(boilerplate).AppendLine()
+
+                let code =
+                    (sb, _assemblyAttributes)
+                    ||> Array.fold (fun (sb: StringBuilder) (item: ITaskItem) ->
+                        sb.AppendLine(this.GenerateAttribute(item, _language.ToLowerInvariant())))
+
+                if _language.ToLowerInvariant() = "f#" then
+                    code.AppendLine("do()") |> ignore
+
+                let fileName = outputFile.ItemSpec
+
+                let outputFileItem =
+                    match _outputDirectory with
+                    | Null -> outputFile
+                    | NonNull outputDirectory ->
+                        if Path.IsPathRooted(fileName) then
+                            outputFile
+                        else
+                            TaskItem(Path.Combine(outputDirectory.ItemSpec, fileName)) :> ITaskItem
+
+                let codeText = code.ToString()
+                File.WriteAllText(fileName, codeText)
+                _outputFile <- outputFileItem
+                not this.Log.HasLoggedErrors
+        with TaskFailed ->
+            false
diff --git a/tests/FSharp.Build.UnitTests/WriteCodeFragmentTests.fs b/tests/FSharp.Build.UnitTests/WriteCodeFragmentTests.fs
index d295f60f4ee..49ad920c449 100644
--- a/tests/FSharp.Build.UnitTests/WriteCodeFragmentTests.fs
+++ b/tests/FSharp.Build.UnitTests/WriteCodeFragmentTests.fs
@@ -13,7 +13,7 @@ type WriteCodeFragmentFSharpTests() =
     let verifyAttribute (attributeName:string) (parameters:(string*string) list) (expectedAttributeText:string) =
         let taskItem = TaskItem(attributeName)
         parameters |> List.iter (fun (key, value) -> taskItem.SetMetadata(key, value))
-        let actualAttributeText = WriteCodeFragment.GenerateAttribute (taskItem :> ITaskItem, "f#")
+        let actualAttributeText = (new WriteCodeFragment()).GenerateAttribute (taskItem :> ITaskItem, "f#")
         let fullExpectedAttributeText = "[<assembly: " + expectedAttributeText + ">]"
         Assert.AreEqual(fullExpectedAttributeText, actualAttributeText)
 
@@ -43,7 +43,7 @@ type WriteCodeFragmentCSharpTests() =
     let verifyAttribute (attributeName:string) (parameters:(string*string) list) (expectedAttributeText:string) =
         let taskItem = TaskItem(attributeName)
         parameters |> List.iter (fun (key, value) -> taskItem.SetMetadata(key, value))
-        let actualAttributeText = WriteCodeFragment.GenerateAttribute (taskItem :> ITaskItem, "c#")
+        let actualAttributeText = (new WriteCodeFragment()).GenerateAttribute (taskItem :> ITaskItem, "c#")
         let fullExpectedAttributeText = "[assembly: " + expectedAttributeText + "]"
         Assert.AreEqual(fullExpectedAttributeText, actualAttributeText)
 
@@ -75,7 +75,7 @@ type WriteCodeFragmentVisualBasicTests() =
     let verifyAttribute (attributeName:string) (parameters:(string*string) list) (expectedAttributeText:string) =
         let taskItem = TaskItem(attributeName)
         parameters |> List.iter (fun (key, value) -> taskItem.SetMetadata(key, value))
-        let actualAttributeText = WriteCodeFragment.GenerateAttribute (taskItem :> ITaskItem, "vb")
+        let actualAttributeText = (new WriteCodeFragment()).GenerateAttribute (taskItem :> ITaskItem, "vb")
         let fullExpectedAttributeText = "<Assembly: " + expectedAttributeText + ">"
         Assert.AreEqual(fullExpectedAttributeText, actualAttributeText)