Fix 944 (#967)

* Preserve the abstract keyword instead of the member for signature type members. Fixes #944

* Bumped alpha version and corrected unit test.

* Preserve both keywords

Author: nojaf

RELEASE_NOTES.md

@@ -1,4 +1,4 @@
-### 4.0.0-alpha-013 - 07/2020
+### 4.0.0-alpha-014 - 07/2020
 * WIP for [#705](https://github.com/fsprojects/fantomas/issues/705)
 * FCS 36.0.3
 * Replaced json configuration with .editorconfig

src/Fantomas.CoreGlobalTool.Tests/Fantomas.CoreGlobalTool.Tests.fsproj

@@ -4,7 +4,7 @@
     <TargetFramework>netcoreapp3.1</TargetFramework>
     <IsPackable>false</IsPackable>
     <GenerateProgramFile>false</GenerateProgramFile>
-    <Version>4.0.0-alpha-013</Version>
+    <Version>4.0.0-alpha-014</Version>
     <NoWarn>FS0988</NoWarn>
   </PropertyGroup>
   <ItemGroup>

src/Fantomas.CoreGlobalTool/Fantomas.CoreGlobalTool.fsproj

@@ -4,7 +4,7 @@
     <TargetFramework>netcoreapp3.1</TargetFramework>
     <ToolCommandName>fantomas</ToolCommandName>
     <PackAsTool>True</PackAsTool>
-    <Version>4.0.0-alpha-013</Version>
+    <Version>4.0.0-alpha-014</Version>
     <AssemblyName>fantomas-tool</AssemblyName>
   </PropertyGroup>
   <ItemGroup>

src/Fantomas.Tests/Fantomas.Tests.fsproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <Import Project="..\netfx.props" />
   <PropertyGroup>
-    <Version>4.0.0-alpha-013</Version>
+    <Version>4.0.0-alpha-014</Version>
     <NoWarn>FS0988</NoWarn>
     <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>

src/Fantomas.Tests/SignatureTests.fs

@@ -524,7 +524,7 @@ type internal Foo2 =
 namespace Foo
 
 type internal Foo2 =
-    member Bar<'k> : unit -> unit when 'k: comparison
+    abstract member Bar<'k> : unit -> unit when 'k: comparison
 """
 
 [<Test>]
@@ -663,3 +663,23 @@ namespace B
 type Foo =
     member Item : 't -> unit when 't : comparison with set
 """
+
+[<Test>]
+let ``preserve abstract member in type, 944`` () =
+    formatSourceString true """
+namespace Baz
+
+type Foo =
+    abstract member Bar : Type
+    abstract Bar2 : Type
+    member Bar3 : Type
+"""  { config with SpaceBeforeColon = true }
+    |> prepend newline
+    |> should equal """
+namespace Baz
+
+type Foo =
+    abstract member Bar : Type
+    abstract Bar2 : Type
+    member Bar3 : Type
+"""

src/Fantomas/CodePrinter.fs

@@ -860,7 +860,7 @@ and genMemberFlagsForMemberBinding astContext (mf:MemberFlags) (rangeOfBindingAn
                     tn.ContentItself
                     |> Option.bind (fun tc ->
                         match tc with
-                        | Keyword({ Content = ("override" | "default" | "member" | "abstract") as kw }) -> Some (!- (kw + " "))
+                        | Keyword({ Content = ("override" | "default" | "member" | "abstract" | "abstract member") as kw }) -> Some (!- (kw + " "))
                         | _ -> None
                     )
                 )

src/Fantomas/Fantomas.fsproj

@@ -4,7 +4,7 @@
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
     <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies>
-    <Version>4.0.0-alpha-013</Version>
+    <Version>4.0.0-alpha-014</Version>
     <Description>Source code formatter for F#</Description>
   </PropertyGroup>
   <ItemGroup>

src/Fantomas/Trivia.fs

@@ -282,7 +282,25 @@ let private addTriviaToTriviaNode
 
     | { Item = Keyword({ Content = keyword} as kw); Range = range } when (keyword = "override" || keyword = "default" || keyword = "member" || keyword = "abstract") ->
         findMemberDefnMemberNodeOnLine triviaNodes range.StartLine
-        |> updateTriviaNode (fun tn -> tn.ContentItself <- Some (Keyword(kw))) triviaNodes
+        |> updateTriviaNode (fun tn ->
+            match tn.Type, tn.ContentItself with
+            | MainNode ("SynMemberSig.Member"), Some (Keyword ({ Content = existingKeywordContent } as token)) when existingKeywordContent =
+                                                                                                                        "abstract"
+                                                                                                                    && keyword =
+                                                                                                                        "member" ->
+                // Combine the two tokens to appear as one
+                let tokenInfo =
+                    { token.TokenInfo with
+                          RightColumn = kw.TokenInfo.RightColumn }
+
+                let combinedKeyword =
+                    { token with
+                          Content = "abstract member"
+                          TokenInfo = tokenInfo }
+
+                tn.ContentItself <- Some(Keyword(combinedKeyword))
+            | _ -> tn.ContentItself <- Some(Keyword(kw))
+        ) triviaNodes
 
     | { Item = Keyword({ TokenInfo = {TokenName = tn}} as kw); Range = range } when (tn = "QMARK") ->
         findConstNodeAfter triviaNodes range