Put long multiline constrained SRTP on separate lines. (#2263)

* Put long multiline constrained SRTP on separate lines. Fixes #2230.

* Reuse genTypeList in genConstraints.

CHANGELOG.md

@@ -6,6 +6,9 @@
 * Idempotency problem with ParsedHashDirective in signature file. [#2258](https://github.com/fsprojects/fantomas/issues/2258)
 * Keyword 'override' gets changed to 'member'. [#2221](https://github.com/fsprojects/fantomas/issues/2221)
 
+### Changed
+* Formatting of multi-constrained SRTP functions needs improvement. [#2230](https://github.com/fsprojects/fantomas/issues/2230)
+
 ## [5.0.0-alpha-007] - 2022-05-16
 
 ### Changed

src/Fantomas.Core.Tests/SignatureTests.fs

@@ -735,8 +735,9 @@ module Foo =
 namespace Blah
 
 module Foo =
-    val inline sum: ('a -> ^value) -> 'a Foo -> ^value
-        when ^value: (static member (+): ^value * ^value -> ^value) and ^value: (static member Zero: ^value)
+    val inline sum:
+        ('a -> ^value) -> 'a Foo -> ^value
+            when ^value: (static member (+): ^value * ^value -> ^value) and ^value: (static member Zero: ^value)
 """
 
 [<Test>]
@@ -1909,6 +1910,128 @@ namespace Microsoft.FSharp.Control
 [<Sealed>]
 [<CompiledName("FSharpAsync")>]
 type Async =
-    static member AwaitEvent: event: IEvent<'Del, 'T> * ?cancelAction: (unit -> unit) -> Async<'T>
-        when 'Del: delegate<'T, unit> and 'Del :> System.Delegate
+    static member AwaitEvent:
+        event: IEvent<'Del, 'T> * ?cancelAction: (unit -> unit) -> Async<'T>
+            when 'Del: delegate<'T, unit> and 'Del :> System.Delegate
+"""
+
+[<Test>]
+let ``multi-constrained SRTP functions, 2230`` () =
+    formatSourceString
+        true
+        """
+/// Throws <c>ArgumentException</c>
+/// </example>
+[<CompiledName("Average")>]
+val inline average   : array:^T[] -> ^T   
+                            when ^T : (static member ( + ) : ^T * ^T -> ^T) 
+                            and  ^T : (static member DivideByInt : ^T*int -> ^T) 
+                            and  ^T : (static member Zero : ^T)
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+/// Throws <c>ArgumentException</c>
+/// </example>
+[<CompiledName("Average")>]
+val inline average:
+    array: ^T[] -> ^T
+        when ^T: (static member (+): ^T * ^T -> ^T)
+        and ^T: (static member DivideByInt: ^T * int -> ^T)
+        and ^T: (static member Zero: ^T)
+"""
+
+[<Test>]
+let ``long curried value with constraints`` () =
+    formatSourceString
+        true
+        """
+[<CompiledName("Average")>]
+val inline average: array: ^T[] -> array: ^T[] -> array: ^T[] -> array: ^T[] -> array: ^T[] -> array: ^T[] -> array: ^T[] -> array: ^T[] -> array: ^T[] -> ^T
+    when ^T: (static member (+): ^T * ^T -> ^T)
+    and ^T: (static member DivideByInt: ^T * int -> ^T)
+    and ^T: (static member Zero: ^T)
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+[<CompiledName("Average")>]
+val inline average:
+    array: ^T[] ->
+    array: ^T[] ->
+    array: ^T[] ->
+    array: ^T[] ->
+    array: ^T[] ->
+    array: ^T[] ->
+    array: ^T[] ->
+    array: ^T[] ->
+    array: ^T[] ->
+        ^T
+        when ^T: (static member (+): ^T * ^T -> ^T)
+        and ^T: (static member DivideByInt: ^T * int -> ^T)
+        and ^T: (static member Zero: ^T)
+"""
+
+[<Test>]
+let ``long tupled value with constraints`` () =
+    formatSourceString
+        true
+        """
+[<CompiledName("Average")>]
+val inline average: array: ^T[] * array: ^T[] * array: ^T[] * array: ^T[] * array: ^T[] * array: ^T[] * array: ^T[] * array: ^T[] * array: ^T[] -> ^T
+    when ^T: (static member (+): ^T * ^T -> ^T)
+    and ^T: (static member DivideByInt: ^T * int -> ^T)
+    and ^T: (static member Zero: ^T)
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+[<CompiledName("Average")>]
+val inline average:
+    array: ^T[] *
+    array: ^T[] *
+    array: ^T[] *
+    array: ^T[] *
+    array: ^T[] *
+    array: ^T[] *
+    array: ^T[] *
+    array: ^T[] *
+    array: ^T[] ->
+        ^T
+        when ^T: (static member (+): ^T * ^T -> ^T)
+        and ^T: (static member DivideByInt: ^T * int -> ^T)
+        and ^T: (static member Zero: ^T)
+"""
+
+[<Test>]
+let ``long mixed curried and tuple value with constraints`` () =
+    formatSourceString
+        true
+        """
+[<CompiledName("Average")>]
+val inline average: array: ^T[] * array: ^T[] * array: ^T[] -> array: ^T[] * array: ^T[] * array: ^T[] -> array: ^T[] * array: ^T[] * array: ^T[] -> ^T
+    when ^T: (static member (+): ^T * ^T -> ^T)
+    and ^T: (static member DivideByInt: ^T * int -> ^T)
+    and ^T: (static member Zero: ^T)
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+[<CompiledName("Average")>]
+val inline average:
+    array: ^T[] * array: ^T[] * array: ^T[] ->
+        array: ^T[] * array: ^T[] * array: ^T[] ->
+            array: ^T[] * array: ^T[] * array: ^T[] ->
+                ^T
+        when ^T: (static member (+): ^T * ^T -> ^T)
+        and ^T: (static member DivideByInt: ^T * int -> ^T)
+        and ^T: (static member Zero: ^T)
 """

src/Fantomas.Core/CodePrinter.fs

@@ -4092,43 +4092,23 @@ and genConstraints astContext (t: SynType) (vi: SynValInfo) =
     match t with
     | TWithGlobalConstraints (ti, tcs) ->
         let genType =
-            match ti, vi with
-            | TFuns ts, SynValInfo (curriedArgInfos, returnType) ->
-                let namedArgInfos =
-                    [ yield! curriedArgInfos
-                      yield [ returnType ] ]
-
-                let args = List.zip namedArgInfos ts
-
-                col sepArrow args (fun (argInfo, t) ->
-                    match argInfo, t with
-                    | [], _ -> genType astContext false t
-                    | [ SynArgInfo (_, isOptional, Some ident) ], _ ->
-                        onlyIf isOptional (!- "?")
-                        +> genIdent ident
-                        +> sepColon
-                        +> genType astContext false t
-                    | [ SynArgInfo _ ], _ -> genType astContext false t
-                    | multipleArgInfo, TTuple ts ->
-                        let combined = List.zip multipleArgInfo ts
-
-                        col sepStar combined (fun (argInfo, (_, t)) ->
-                            let genNamed =
-                                match argInfo with
-                                | SynArgInfo (_, isOptional, Some ident) ->
-                                    onlyIf isOptional (!- "?")
-                                    +> genIdent ident
-                                    +> sepColon
-                                | _ -> sepNone
-
-                            genNamed +> genType astContext false t)
-                    | _ -> sepNone)
-            | _ -> genType astContext false ti
-
-        genType
-        +> sepSpaceOrIndentAndNlnIfExpressionExceedsPageWidth (
-            ifElse (List.isNotEmpty tcs) (!- "when ") sepSpace
-            +> col wordAnd tcs (genTypeConstraint astContext)
+            let (FunType namedArgs) = (ti, vi)
+            genTypeList astContext namedArgs
+
+        let genConstraints =
+            let short =
+                ifElse (List.isNotEmpty tcs) (!- "when ") sepSpace
+                +> col wordAnd tcs (genTypeConstraint astContext)
+
+            let long =
+                ifElse (List.isNotEmpty tcs) (!- "when ") sepSpace
+                +> col (sepNln +> wordAndFixed +> sepSpace) tcs (genTypeConstraint astContext)
+
+            expressionFitsOnRestOfLine short long
+
+        autoIndentAndNlnIfExpressionExceedsPageWidth (
+            genType
+            +> sepSpaceOrIndentAndNlnIfExpressionExceedsPageWidth genConstraints
         )
     | _ -> sepNone
 
@@ -4839,7 +4819,6 @@ and genMemberDefn astContext node =
             (match t with
              | TWithGlobalConstraints _ -> true
              | _ -> false)
-            autoIndentAndNlnIfExpressionExceedsPageWidth
             (genConstraints astContext t vi)
 
     | md -> failwithf "Unexpected member definition: %O" md

src/Fantomas.Core/Context.fs

@@ -650,6 +650,7 @@ let internal rep n (f: Context -> Context) (ctx: Context) =
     [ 1..n ] |> List.fold (fun c _ -> f c) ctx
 
 let internal wordAnd = !- " and "
+let internal wordAndFixed = !- "and"
 let internal wordOr = !- " or "
 let internal wordOf = !- " of "
 // Separator functions