Fix 13926 - Disallow using base to invoke an abstract base method.

docs/release-notes/.FSharp.Compiler.Service/8.0.300.md

@@ -15,6 +15,7 @@
 * Fix release inline optimization, which leads to MethodAccessException if used with `assembly:InternalsVisibleTo`` attribute. ([Issue #16105](https://github.com/dotnet/fsharp/issues/16105), ([PR #16737](https://github.com/dotnet/fsharp/pull/16737))
 * Enforce AttributeTargets on let values and functions. ([PR #16692](https://github.com/dotnet/fsharp/pull/16692))
 * Enforce AttributeTargets on union case declarations. ([PR #16764](https://github.com/dotnet/fsharp/pull/16764))
+* Disallow using base to invoke an abstract base method. ([Issue #13926](https://github.com/dotnet/fsharp/issues/13926), [PR #16773](https://github.com/dotnet/fsharp/pull/16773))
 
 ### Added
 

docs/release-notes/.Language/8.0.md

@@ -1,3 +1,7 @@
-### Added
+### Fixed
 
-* `while!` ([Language suggestion #1038](https://github.com/fsharp/fslang-suggestions/issues/1038), [PR #14238](https://github.com/dotnet/fsharp/pull/14238))
+* Disallow using base to invoke an abstract base method ([Issue #13926](https://github.com/dotnet/fsharp/issues/13926), [PR #16773](https://github.com/dotnet/fsharp/pull/16773))
+
+### Added
+
+* `while!` ([Language suggestion #1038](https://github.com/fsharp/fslang-suggestions/issues/1038), [PR #14238](https://github.com/dotnet/fsharp/pull/14238))

src/Compiler/AbstractIL/il.fs

@@ -5640,10 +5640,8 @@ let resolveILMethodRefWithRescope r (td: ILTypeDef) (mref: ILMethodRef) =
         possibles
         |> List.filter (fun md ->
             mref.CallingConv = md.CallingConv
-            &&
-            // REVIEW: this uses equality on ILType. For CMOD_OPTIONAL this is not going to be correct
-            (md.Parameters, argTypes)
-            ||> List.lengthsEqAndForall2 (fun p1 p2 -> r p1.Type = p2)
+            && (md.Parameters, argTypes)
+               ||> List.lengthsEqAndForall2 (fun p1 p2 -> r p1.Type = p2)
             &&
             // REVIEW: this uses equality on ILType. For CMOD_OPTIONAL this is not going to be correct
             r md.Return.Type = retType)

src/Compiler/Checking/PostInferenceChecks.fs

@@ -1307,14 +1307,14 @@ and CheckILBaseCall cenv env (ilMethRef, enclTypeInst, methInst, retTypes, tyarg
     match tryTcrefOfAppTy g baseVal.Type with
     | ValueSome tcref when tcref.IsILTycon ->
         try
-            // This is awkward - we have to explicitly re-resolve back to the IL metadata to determine if the method is abstract.
-            // We believe this may be fragile in some situations, since we are using the Abstract IL code to compare
-            // type equality, and it would be much better to remove any F# dependency on that implementation of IL type
-            // equality. It would be better to make this check in tc.fs when we have the Abstract IL metadata for the method to hand.
-            let mdef = resolveILMethodRef tcref.ILTyconRawMetadata ilMethRef
+            let mdef =
+                match tcref.ILTyconInfo with
+                | TILObjectReprData(scoref, _, _) ->
+                    resolveILMethodRefWithRescope (rescopeILType scoref) tcref.ILTyconRawMetadata ilMethRef
+
             if mdef.IsAbstract then
                 errorR(Error(FSComp.SR.tcCannotCallAbstractBaseMember(mdef.Name), m))
-        with _ -> () // defensive coding
+        with _ -> ()
     | _ -> ()
 
     CheckTypeInstNoByrefs cenv env m tyargs

src/Compiler/FSharp.Compiler.Service.fsproj

@@ -76,8 +76,8 @@
     <InternalsVisibleTo Include="LanguageServiceProfiling" />
     <InternalsVisibleTo Include="FSharp.Compiler.Benchmarks" />
     <InternalsVisibleTo Include="HistoricalBenchmark" />
-	<InternalsVisibleTo Include="FSharp.Test.Utilities" />
-	<InternalsVisibleTo Include="FSharp.Editor" />
+    <InternalsVisibleTo Include="FSharp.Test.Utilities" />
+    <InternalsVisibleTo Include="FSharp.Editor" />
   </ItemGroup>
 
   <ItemGroup>
@@ -365,8 +365,8 @@
     <Compile Include="Checking\CheckIncrementalClasses.fs" />
     <Compile Include="Checking\CheckDeclarations.fsi" />
     <Compile Include="Checking\CheckDeclarations.fs" />
-	<Compile Include="Checking\SignatureHash.fsi" />
-	<Compile Include="Checking\SignatureHash.fs" />
+    <Compile Include="Checking\SignatureHash.fsi" />
+    <Compile Include="Checking\SignatureHash.fs" />
     <Compile Include="Optimize\Optimizer.fsi" />
     <Compile Include="Optimize\Optimizer.fs" />
     <Compile Include="Optimize\DetupleArgs.fsi" />
@@ -504,12 +504,12 @@
     <Compile Include="Service\QuickParse.fsi" />
     <Compile Include="Service\QuickParse.fs" />
     <Compile Include="Service\FSharpCheckerResults.fsi" />
-	  <Compile Include="Service\FSharpCheckerResults.fs" />
-	  <Compile Include="Service\FSharpProjectSnapshot.fs" />
-	  <Compile Include="Service\BackgroundCompiler.fsi" />
-	  <Compile Include="Service\BackgroundCompiler.fs" />
-	  <Compile Include="Service\TransparentCompiler.fsi" />
-	  <Compile Include="Service\TransparentCompiler.fs" />
+    <Compile Include="Service\FSharpCheckerResults.fs" />
+    <Compile Include="Service\FSharpProjectSnapshot.fs" />
+    <Compile Include="Service\BackgroundCompiler.fsi" />
+    <Compile Include="Service\BackgroundCompiler.fs" />
+    <Compile Include="Service\TransparentCompiler.fsi" />
+    <Compile Include="Service\TransparentCompiler.fs" />
     <Compile Include="Service\service.fsi" />
     <Compile Include="Service\service.fs" />
     <Compile Include="Service\ServiceInterfaceStubGenerator.fsi" />

tests/FSharp.Compiler.ComponentTests/Conformance/BasicGrammarElements/ImportDeclarations/ImportDeclarations.fs

@@ -107,4 +107,75 @@ module ImportDeclarations =
         |> verifyCompileAndRun
         |> shouldSucceed
 
+    [<FactForNETCOREAPP>]
+    let ImplementImportedAbstractBaseMethodsFailsIfUsed ()=
+        FSharp """
+module Testing
 
+open System.Text.Json
+open System.Text.Json.Serialization
+
+type StringTrimJsonSerializer(o: JsonSerializerOptions) =
+    inherit JsonConverter<string>()
+
+    override this.Read(reader, _, _) =
+        match reader.TokenType with
+        | JsonTokenType.String -> reader.GetString().Trim()
+        | _ -> JsonException("Type is not a string") |> raise
+
+    override this.Write(writer, objectToWrite, options) = base.Write(writer, objectToWrite, options)
+
+type SomeType = { AField: string }
+
+let serialize item =
+    let options = JsonSerializerOptions()
+    StringTrimJsonSerializer options |> options.Converters.Add
+    JsonSerializer.Serialize(item, options)
+
+[<EntryPoint>]
+let main _ =
+    { AField = "a" }
+    |> serialize
+    |> ignore
+    0"""
+        |> verifyCompile
+        |> shouldFail
+        |> withDiagnostics [
+            (Error 1201, Line 15, Col 59, Line 15, Col 101, "Cannot call an abstract base member: 'Write'")
+        ]
+
+
+    [<FactForNETCOREAPP>]
+    let ImplementImportedAbstractBaseMethodsFailsIfNotUsed ()=
+        FSharp """
+module Testing
+
+open System.Text.Json
+open System.Text.Json.Serialization
+
+type StringTrimJsonSerializer(o: JsonSerializerOptions) =
+    inherit JsonConverter<string>()
+    override this.Read(reader, _, _) =
+        match reader.TokenType with
+        | JsonTokenType.String -> reader.GetString().Trim()
+        | _ -> JsonException("Type is not a string") |> raise
+    override this.Write(writer, objectToWrite, options) = base.Write(writer, objectToWrite, options)
+
+type SomeType = { AField: int }
+
+let serialize item =
+    let options = JsonSerializerOptions()
+    StringTrimJsonSerializer options |> options.Converters.Add
+    JsonSerializer.Serialize(item, options)
+
+[<EntryPoint>]
+let main _ =
+    { AField = 1 }
+    |> serialize
+    |>ignore
+    0"""
+        |> verifyCompile
+        |> shouldFail
+        |> withDiagnostics [
+            (Error 1201, Line 13, Col 59, Line 13, Col 101, "Cannot call an abstract base member: 'Write'")
+        ]

tests/FSharp.Compiler.ComponentTests/ErrorMessages/SuggestionsTests.fs

@@ -139,12 +139,12 @@ open Collectons
     [<Fact>]
     let ``Suggest Namespaces`` () =
         FSharp """
-open System.Collectons
+open System.Lema
         """
         |> typecheck
         |> shouldFail
-        |> withSingleDiagnostic (Error 39, Line 2, Col 13, Line 2, Col 23,
-                                 "The namespace 'Collectons' is not defined.")
+        |> withSingleDiagnostic (Error 39, Line 2, Col 13, Line 2, Col 17,
+                                 "The namespace 'Lema' is not defined.")
 
     [<Fact>]
     let ``Suggest Record Labels`` () =

tests/FSharp.Compiler.ComponentTests/FSharp.Compiler.ComponentTests.fsproj

@@ -19,7 +19,7 @@
     <DefineConstants Condition="'$(Configuration)'=='debug'">$(DefineConstants);DEBUG</DefineConstants>
     <!-- allow testing of static methods in interfaces on .NET 6  -->
     <EnablePreviewFeatures>true</EnablePreviewFeatures>
-	  <EnableUnsafeBinaryFormatterSerialization>true</EnableUnsafeBinaryFormatterSerialization>
+    <EnableUnsafeBinaryFormatterSerialization>true</EnableUnsafeBinaryFormatterSerialization>
 </PropertyGroup>
 
 <PropertyGroup Condition="'$(BUILDING_USING_DOTNET)' == 'true'">
@@ -228,9 +228,9 @@
     <Compile Include="Language\SequenceExpressionTests.fs" />
     <Compile Include="Language\StaticClassTests.fs" />
     <Compile Include="Language\PrintfFormatTests.fs" />
-  	<Compile Include="Language\InterfaceTests.fs" />
-	  <Compile Include="Language\CopyAndUpdateTests.fs" />
-	  <Compile Include="Language\ConstraintIntersectionTests.fs" />
+    <Compile Include="Language\InterfaceTests.fs" />
+    <Compile Include="Language\CopyAndUpdateTests.fs" />
+    <Compile Include="Language\ConstraintIntersectionTests.fs" />
     <Compile Include="Language\BooleanReturningAndReturnTypeDirectedPartialActivePatternTests.fs" />
     <Compile Include="ConstraintSolver\PrimitiveConstraints.fs" />
     <Compile Include="ConstraintSolver\MemberConstraints.fs" />
@@ -280,7 +280,7 @@
     <Compile Include="CompilerService\RangeModule.fs" />
     <Compile Include="CompilerService\LruCache.fs" />
     <Compile Include="CompilerService\AsyncLock.fs" />
-	  <Compile Include="CompilerService\AsyncMemoize.fs" />
+    <Compile Include="CompilerService\AsyncMemoize.fs" />
     <Compile Include="Debugger\PortablePdbs.fs" />
     <Compile Include="Diagnostics\async.fs" />
     <Compile Include="Diagnostics\General.fs" />
@@ -313,14 +313,12 @@
     <Compile Include="FSharpChecker\TransparentCompiler.fs" />
     <Compile Include="FSharpChecker\SymbolUse.fs" />
     <Compile Include="FSharpChecker\FindReferences.fs" />
-    <None Include="**\*.cs;**\*.fs;**\*.fsx;**\*.fsi" Exclude="@(Compile)">
-	    <Link>%(RelativeDir)TestSource\%(Filename)%(Extension)</Link>
-    </None>
   </ItemGroup>
 
-  <ItemGroup />
-
   <ItemGroup>
+    <None Include="**\*.cs;**\*.fs;**\*.fsx;**\*.fsi" Exclude="@(Compile)">
+      <Link>%(RelativeDir)TestSource\%(Filename)%(Extension)</Link>
+    </None>
     <None Include="**\*.bsl">
       <Link>%(RelativeDir)\BaseLine\%(Filename)%(Extension)</Link>
     </None>
@@ -331,6 +329,7 @@
     <EmbeddedResource Remove="Properties\**" />
     <Content Include="xunit.runner.json" CopyToOutputDirectory="PreserveNewest" />
   </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="$(FSharpSourcesRoot)\Compiler\FSharp.Compiler.Service.fsproj" />
     <ProjectReference Include="$(FSharpSourcesRoot)\FSharp.Compiler.Interactive.Settings\FSharp.Compiler.Interactive.Settings.fsproj" />