From b910496974ad349aac444ca9cefd0f96dc1490d7 Mon Sep 17 00:00:00 2001
From: dawe <dawedawe@posteo.de>
Date: Tue, 9 Nov 2021 22:34:41 +0100
Subject: [PATCH 1/2] Fix 1954: val mutable in signature loses 'mutable'

---
 src/Fantomas.Tests/SignatureTests.fs | 18 ++++++++++++++++++
 src/Fantomas/CodePrinter.fs          |  5 +++--
 src/Fantomas/SourceParser.fs         |  4 ++--
 3 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/src/Fantomas.Tests/SignatureTests.fs b/src/Fantomas.Tests/SignatureTests.fs
index 8f1ee43040..4094f5f933 100644
--- a/src/Fantomas.Tests/SignatureTests.fs
+++ b/src/Fantomas.Tests/SignatureTests.fs
@@ -171,6 +171,24 @@ module Tainted
 val GetHashCodeTainted: (Tainted<'T> -> int) when 'T: equality
 """
 
+[<Test>]
+let ``should keep mutable in type signature`` () =
+    formatSourceString
+        true
+        """
+module Tainted
+val mutable showParserStackOnParseError: bool
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+module Tainted
+
+val mutable showParserStackOnParseError: bool
+"""
+
 [<Test>]
 let ``should keep access modifiers in signatures seperated`` () =
     formatSourceString
diff --git a/src/Fantomas/CodePrinter.fs b/src/Fantomas/CodePrinter.fs
index b41aee054e..d5c18d0289 100644
--- a/src/Fantomas/CodePrinter.fs
+++ b/src/Fantomas/CodePrinter.fs
@@ -923,7 +923,7 @@ and genMemberFlagsForMemberBinding astContext (mf: SynMemberFlags) (rangeOfBindi
             |> Option.defaultValue (!- "override ")
         <| ctx
 
-and genVal astContext (Val (ats, px, ao, s, identRange, t, vi, isInline, tds, eo, range)) =
+and genVal astContext (Val (ats, px, ao, s, identRange, t, vi, isInline, isMutable, tds, eo, range)) =
     let typeName = genTypeAndParam astContext s tds []
 
     let (FunType namedArgs) = (t, vi)
@@ -933,6 +933,7 @@ and genVal astContext (Val (ats, px, ao, s, identRange, t, vi, isInline, tds, eo
     +> genAttributes astContext ats
     +> (!- "val "
         +> onlyIf isInline (!- "inline ")
+        +> onlyIf isMutable (!- "mutable ")
         +> opt sepSpace ao genAccess
         +> typeName
         |> genTriviaFor Ident_ identRange)
@@ -4195,7 +4196,7 @@ and genMemberSig astContext node =
         | SynMemberSig.NestedType (_, r) -> r, SynMemberSig_NestedType
 
     match node with
-    | MSMember (Val (ats, px, ao, s, _, t, vi, isInline, tds, eo, _), mf) ->
+    | MSMember (Val (ats, px, ao, s, _, t, vi, isInline, _, tds, eo, _), mf) ->
         let (FunType namedArgs) = (t, vi)
 
         let isFunctionProperty =
diff --git a/src/Fantomas/SourceParser.fs b/src/Fantomas/SourceParser.fs
index d0cef9fb47..e6457ec90b 100644
--- a/src/Fantomas/SourceParser.fs
+++ b/src/Fantomas/SourceParser.fs
@@ -1565,13 +1565,13 @@ let (|Val|)
                 t,
                 vi,
                 isInline,
-                _,
+                isMutable,
                 px,
                 ao,
                 eo,
                 range))
     =
-    (ats, px, ao, s, ident.idRange, t, vi, isInline, typars, eo, range)
+    (ats, px, ao, s, ident.idRange, t, vi, isInline, isMutable, typars, eo, range)
 
 // Misc
 

From 7ab04773a89c850bcb24eaa63485629ddda029a9 Mon Sep 17 00:00:00 2001
From: dawe <dawedawe@posteo.de>
Date: Tue, 9 Nov 2021 22:56:02 +0100
Subject: [PATCH 2/2] Add issue number to test name

---
 src/Fantomas.Tests/SignatureTests.fs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Fantomas.Tests/SignatureTests.fs b/src/Fantomas.Tests/SignatureTests.fs
index 4094f5f933..bc645c0182 100644
--- a/src/Fantomas.Tests/SignatureTests.fs
+++ b/src/Fantomas.Tests/SignatureTests.fs
@@ -172,7 +172,7 @@ val GetHashCodeTainted: (Tainted<'T> -> int) when 'T: equality
 """
 
 [<Test>]
-let ``should keep mutable in type signature`` () =
+let ``should keep mutable in type signature, 1954`` () =
     formatSourceString
         true
         """