Disallow abstract member with access modifiers in sig file

docs/release-notes/.FSharp.Compiler.Service/9.0.200.md

@@ -3,7 +3,8 @@
 * Fix false negatives for passing null to "obj" arguments. Only "obj | null" can now subsume any type ([PR #17757](https://github.com/dotnet/fsharp/pull/17757))
 * Fix internal error when calling 'AddSingleton' and other overloads only differing in generic arity ([PR #17804](https://github.com/dotnet/fsharp/pull/17804))
 * Fix extension methods support for non-reference system assemblies ([PR #17799](https://github.com/dotnet/fsharp/pull/17799))
-* Ensure `frameworkTcImportsCache` mutations are thread-safe. ([PR #17795](https://github.com/dotnet/fsharp/pull/17795))
+* Ensure `frameworkTcImportsCache` mutations are threadsafe. ([PR #17795](https://github.com/dotnet/fsharp/pull/17795))
+* Disallow abstract member with access modifiers in sig file. ([PR #17802](https://github.com/dotnet/fsharp/pull/17802))
 * Fix concurrency issue in `ILPreTypeDefImpl`  ([PR #17812](https://github.com/dotnet/fsharp/pull/17812))
 
 ### Added

src/Compiler/Service/FSharpSource.fsi

@@ -26,7 +26,7 @@ type internal FSharpSource =
     abstract TimeStamp: DateTime
 
     /// Gets the internal text container. Text may be on-disk, in a stream, or a source text.
-    abstract internal GetTextContainer: unit -> Async<TextContainer>
+    abstract GetTextContainer: unit -> Async<TextContainer>
 
     /// Creates a FSharpSource from disk. Only used internally.
     static member internal CreateFromFile: filePath: string -> FSharpSource

src/Compiler/SyntaxTree/ParseHelpers.fs

@@ -1228,3 +1228,11 @@ let mkValField
         mkSynField parseState idOpt typ isMutable access attribs mStaticOpt rangeStart (Some leadingKeyword)
 
     SynMemberDefn.ValField(field, field.Range)
+
+let leadingKeywordIsAbstract =
+    function
+    | SynLeadingKeyword.Abstract _
+    | SynLeadingKeyword.AbstractMember _
+    | SynLeadingKeyword.StaticAbstract _
+    | SynLeadingKeyword.StaticAbstractMember _ -> true
+    | _ -> false

src/Compiler/SyntaxTree/ParseHelpers.fsi

@@ -302,3 +302,5 @@ val mkSynField:
     rangeStart: range ->
     leadingKeyword: SynLeadingKeyword option ->
         SynField
+
+val leadingKeywordIsAbstract: SynLeadingKeyword -> bool

src/Compiler/pars.fsy

@@ -985,8 +985,11 @@ classMemberSpfn:
                match optLiteralValue with
                | None -> m
                | Some e -> unionRanges m e.Range
-
+        
        let flags, leadingKeyword = $3
+       if leadingKeywordIsAbstract leadingKeyword && (Option.isSome $5 || Option.isSome getterAccess || Option.isSome setterAccess)
+       then errorR(Error(FSComp.SR.parsAccessibilityModsIllegalForAbstract(), mWhole))
+
        let flags = flags (getSetAdjuster arity)
        let trivia = { LeadingKeyword = leadingKeyword; InlineKeyword = $4; WithKeyword = mWith; EqualsRange = mEquals }
        let valSpfn = SynValSig($1, id, explicitValTyparDecls, ty, arity, isInline, false, doc, vis2, optLiteralValue, mWhole, trivia)

tests/FSharp.Compiler.ComponentTests/Conformance/BasicGrammarElements/AccessibilityAnnotations/PermittedLocations/PermittedLocations.fs

@@ -160,3 +160,30 @@ module AccessibilityAnnotations_PermittedLocations =
         |> withDiagnostics [
             (Error 531, Line 8, Col 13, Line 8, Col 20, "Accessibility modifiers should come immediately prior to the identifier naming a construct")
         ]
+
+    [<Fact>]
+    let ``Signature File Test: abstract member cannot have access modifiers`` () =
+        Fsi """module Program
+
+type A =
+    abstract internal B: int ->int
+    abstract member internal E: int ->int
+    abstract member C: int with internal get, private set
+    abstract internal D: int with get, set
+    static abstract internal B2: int ->int
+    static abstract member internal E2: int ->int
+    static abstract member C2: int with internal get, private set
+    static abstract internal D2: int with get, set""" 
+        |> withOptions ["--nowarn:3535"]
+        |> verifyCompile
+        |> shouldFail
+        |> withDiagnostics [
+            (Error 0561, Line 4, Col 5, Line 4, Col 35, "Accessibility modifiers are not allowed on this member. Abstract slots always have the same visibility as the enclosing type.")
+            (Error 0561, Line 5, Col 5, Line 5, Col 42, "Accessibility modifiers are not allowed on this member. Abstract slots always have the same visibility as the enclosing type.")
+            (Error 0561, Line 6, Col 5, Line 6, Col 58, "Accessibility modifiers are not allowed on this member. Abstract slots always have the same visibility as the enclosing type.")
+            (Error 0561, Line 7, Col 5, Line 7, Col 43, "Accessibility modifiers are not allowed on this member. Abstract slots always have the same visibility as the enclosing type.")
+            (Error 0561, Line 8, Col 5, Line 8, Col 43, "Accessibility modifiers are not allowed on this member. Abstract slots always have the same visibility as the enclosing type.")
+            (Error 0561, Line 9, Col 5, Line 9, Col 50, "Accessibility modifiers are not allowed on this member. Abstract slots always have the same visibility as the enclosing type.")
+            (Error 0561, Line 10, Col 5, Line 10, Col 66, "Accessibility modifiers are not allowed on this member. Abstract slots always have the same visibility as the enclosing type.")
+            (Error 0561, Line 11, Col 5, Line 11, Col 51, "Accessibility modifiers are not allowed on this member. Abstract slots always have the same visibility as the enclosing type.")
+        ]

tests/FSharp.Compiler.ComponentTests/Conformance/BasicGrammarElements/MemberDefinitions/MethodsAndProperties/AutoPropsWithModifierBeforeGetSet.fs

@@ -132,7 +132,7 @@ type A =
     |> verifyCompile
     |> shouldFail
     |> withDiagnostics [
-        (Error 240, Line 1, Col 1, Line 9, Col 42, "The signature file 'Program' 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.")
+        (Error 0561, Line 9, Col 5, Line 9, Col 42, "Accessibility modifiers are not allowed on this member. Abstract slots always have the same visibility as the enclosing type.")
     ]
 
 [<Fact>]