Fix managed IID_PPV_ARGS overloads for native COM out pointers

src/Microsoft.Windows.CsWin32/Generator.FriendlyOverloads.cs

@@ -154,6 +154,7 @@ private IEnumerable<MethodDeclarationSyntax> DeclareFriendlyOverload(
         int iidPpvRiidOrigIndex = -1;
         int iidPpvPpvOrigIndex = -1;
         bool iidPpvMarshalingMode = false;
+        bool iidPpvUseNativeOutMarshaling = false;
 
         if (this.options.FriendlyOverloads.ComOutPtrGenericOverloads)
         {
@@ -186,10 +187,12 @@ private IEnumerable<MethodDeclarationSyntax> DeclareFriendlyOverload(
                     // Skip if ppv is typed as IntPtr (UseIntPtrForComOutPointers mode).
                     if (ppvExtern.Type is not IdentifierNameSyntax { Identifier.ValueText: nameof(IntPtr) })
                     {
+                        bool ppvExternIsObjectOut = ppvExtern.Modifiers.Any(SyntaxKind.OutKeyword)
+                            && ppvExtern.Type is PredefinedTypeSyntax { Keyword.RawKind: (int)SyntaxKind.ObjectKeyword };
                         iidPpvRiidOrigIndex = riidOrig;
                         iidPpvPpvOrigIndex = ppvOrig;
-                        iidPpvMarshalingMode = ppvExtern.Modifiers.Any(SyntaxKind.OutKeyword)
-                            && ppvExtern.Type is PredefinedTypeSyntax { Keyword.RawKind: (int)SyntaxKind.ObjectKeyword };
+                        iidPpvMarshalingMode = this.options.AllowMarshaling;
+                        iidPpvUseNativeOutMarshaling = iidPpvMarshalingMode && !ppvExternIsObjectOut;
                     }
                 }
             }
@@ -248,28 +251,66 @@ private IEnumerable<MethodDeclarationSyntax> DeclareFriendlyOverload(
             {
                 signatureChanged = true;
                 IdentifierNameSyntax tName = IdentifierName("T");
+                ParameterSyntax ppvExternParam = externMethodDeclaration.ParameterList.Parameters[paramIndex];
+                IdentifierNameSyntax ppvName = IdentifierName(ppvExternParam.Identifier.ValueText);
 
                 if (iidPpvMarshalingMode)
                 {
-                    parameters[paramIndex] = StripAttributes(externMethodDeclaration.ParameterList.Parameters[paramIndex])
+                    parameters[paramIndex] = StripAttributes(ppvExternParam)
                         .WithType(tName.WithTrailingTrivia(TriviaList(Space)))
                         .WithModifiers([TokenWithSpace(SyntaxKind.OutKeyword)]);
 
-                    arguments[paramIndex] = Argument(DeclarationExpression(
-                        PredefinedType(TokenWithSpace(SyntaxKind.ObjectKeyword)),
-                        SingleVariableDesignation(Identifier("__ppv"))))
-                        .WithRefKindKeyword(TokenWithSpace(SyntaxKind.OutKeyword));
+                    if (iidPpvUseNativeOutMarshaling)
+                    {
+                        IdentifierNameSyntax nativeLocal = IdentifierName("__ppv");
+                        leadingOutsideTryStatements.Add(
+                            LocalDeclarationStatement(VariableDeclaration(
+                                PointerType(PredefinedType(Token(SyntaxKind.VoidKeyword))),
+                                [VariableDeclarator(nativeLocal.Identifier, EqualsValueClause(LiteralExpression(SyntaxKind.NullLiteralExpression)))])));
 
-                    IdentifierNameSyntax ppvName = IdentifierName(externMethodDeclaration.ParameterList.Parameters[paramIndex].Identifier.ValueText);
-                    trailingStatements.Add(ExpressionStatement(
-                        AssignmentExpression(
-                            SyntaxKind.SimpleAssignmentExpression,
-                            ppvName,
-                            CastExpression(tName, IdentifierName("__ppv")))));
+                        arguments[paramIndex] = Argument(PrefixUnaryExpression(SyntaxKind.AddressOfExpression, nativeLocal));
+
+                        ExpressionSyntax toManagedExpression = this.useSourceGenerators ?
+                            InvocationExpression(
+                                MemberAccessExpression(
+                                    SyntaxKind.SimpleMemberAccessExpression,
+                                    GenericName($"global::System.Runtime.InteropServices.Marshalling.ComInterfaceMarshaller", [tName]),
+                                    IdentifierName("ConvertToManaged")),
+                                [Argument(nativeLocal)]) :
+                            ParenthesizedExpression(ConditionalExpression(
+                                BinaryExpression(SyntaxKind.NotEqualsExpression, nativeLocal, LiteralExpression(SyntaxKind.NullLiteralExpression)),
+                                CastExpression(tName, InvocationExpression(
+                                    MemberAccessExpression(
+                                        SyntaxKind.SimpleMemberAccessExpression,
+                                        ParseTypeName($"global::System.Runtime.InteropServices.Marshal"),
+                                        IdentifierName("GetObjectForIUnknown")),
+                                    [Argument(CastExpression(ParseName("nint"), nativeLocal))])),
+                                LiteralExpression(SyntaxKind.NullLiteralExpression)));
+
+                        trailingStatements.Add(ExpressionStatement(
+                            AssignmentExpression(
+                                SyntaxKind.SimpleAssignmentExpression,
+                                ppvName,
+                                toManagedExpression)));
+                        finallyStatements.Add(this.COMFreeNativePointerStatement(nativeLocal, tName));
+                    }
+                    else
+                    {
+                        arguments[paramIndex] = Argument(DeclarationExpression(
+                            PredefinedType(TokenWithSpace(SyntaxKind.ObjectKeyword)),
+                            SingleVariableDesignation(Identifier("__ppv"))))
+                            .WithRefKindKeyword(TokenWithSpace(SyntaxKind.OutKeyword));
+
+                        trailingStatements.Add(ExpressionStatement(
+                            AssignmentExpression(
+                                SyntaxKind.SimpleAssignmentExpression,
+                                ppvName,
+                                CastExpression(tName, IdentifierName("__ppv")))));
+                    }
                 }
                 else
                 {
-                    parameters[paramIndex] = StripAttributes(externMethodDeclaration.ParameterList.Parameters[paramIndex])
+                    parameters[paramIndex] = StripAttributes(ppvExternParam)
                         .WithType(PointerType(tName).WithTrailingTrivia(TriviaList(Space)))
                         .WithModifiers([TokenWithSpace(SyntaxKind.OutKeyword)]);
 
@@ -280,7 +321,6 @@ private IEnumerable<MethodDeclarationSyntax> DeclareFriendlyOverload(
 
                     arguments[paramIndex] = Argument(PrefixUnaryExpression(SyntaxKind.AddressOfExpression, IdentifierName("__ppv")));
 
-                    IdentifierNameSyntax ppvName = IdentifierName(externMethodDeclaration.ParameterList.Parameters[paramIndex].Identifier.ValueText);
                     trailingStatements.Add(ExpressionStatement(
                         AssignmentExpression(
                             SyntaxKind.SimpleAssignmentExpression,

test/GenerationSandbox.BuildTask.Tests/COMTests.cs

@@ -18,6 +18,7 @@
 using Windows.Win32.Graphics.Direct2D.Common;
 using Windows.Win32.Graphics.Direct3D;
 using Windows.Win32.Graphics.Direct3D11;
+using Windows.Win32.Graphics.Direct3D12;
 using Windows.Win32.Graphics.Dxgi.Common;
 using Windows.Win32.NetworkManagement.WindowsFirewall;
 using Windows.Win32.Storage.FileSystem;
@@ -33,6 +34,8 @@ namespace GenerationSandbox.BuildTask.Tests;
 [Trait("WindowsOnly", "true")]
 public partial class COMTests(ITestOutputHelper outputHelper)
 {
+    private delegate void CreateCommittedResourceGenericOverloadCompileDelegate(ID3D12Device device, in D3D12_HEAP_PROPERTIES heapProperties, in D3D12_RESOURCE_DESC resourceDesc);
+
     private ITestOutputHelper outputHelper = outputHelper;
 
     [Fact]
@@ -108,6 +111,25 @@ public void IsSHGetFileInfoEasilyCalled()
             SHGFI_FLAGS.SHGFI_DISPLAYNAME);
     }
 
+    [Fact]
+    public void ID3D12Device_CreateCommittedResource_GenericOverloadsCompile()
+    {
+        CreateCommittedResourceGenericOverloadCompileDelegate compileOnly = CompileOnlyCreateCommittedResourceGenericOverload;
+        Assert.NotNull(compileOnly);
+    }
+
+    private static void CompileOnlyCreateCommittedResourceGenericOverload(ID3D12Device device, in D3D12_HEAP_PROPERTIES heapProperties, in D3D12_RESOURCE_DESC resourceDesc)
+    {
+        device.CreateCommittedResource<ID3D12Resource>(
+            in heapProperties,
+            D3D12_HEAP_FLAGS.D3D12_HEAP_FLAG_NONE,
+            in resourceDesc,
+            D3D12_RESOURCE_STATES.D3D12_RESOURCE_STATE_COMMON,
+            null,
+            out ID3D12Resource resource);
+        GC.KeepAlive(resource);
+    }
+
 
     [Fact]
     [Trait("TestCategory", "RequiresHardware")] // D3D APIs fail in cloud VMs

test/GenerationSandbox.BuildTask.Tests/NativeMethods.txt

@@ -25,6 +25,8 @@ HMENU
 ICompositorInterop
 ID2D1HwndRenderTarget
 ID2D1RenderTarget
+ID3D12Device
+ID3D12Resource
 IDebugProperty
 IDispatch
 IEventSubscription
@@ -85,4 +87,4 @@ IEnumVARIANT
 INetFwAuthorizedApplication
 SetupDiGetClassDevs
 SetupDiEnumDeviceInfo
-SetupDiGetDeviceInstanceId
+SetupDiGetDeviceInstanceId

test/Microsoft.Windows.CsWin32.Tests/COMTests.cs

@@ -483,6 +483,46 @@ public void ComOutPtrGenericOverload_D3D12_CreateCommandQueue(bool allowMarshali
             m => m.TypeParameterList?.Parameters.Count == 1);
     }
 
+    /// <summary>
+    /// Regression test for <see href="https://github.com/microsoft/CsWin32/issues/1608">#1608</see>.
+    /// Optional IID_PPV_ARGS out parameters should still get managed generic overloads.
+    /// </summary>
+    [Theory, PairwiseData]
+    public void ComOutPtrGenericOverload_D3D12_OptionalOutCreateCommittedResource(bool useComSourceGenerators)
+    {
+        const string methodName = "CreateCommittedResource";
+        if (useComSourceGenerators)
+        {
+            this.compilation = this.starterCompilations["net10.0"];
+            this.parseOptions = this.parseOptions.WithLanguageVersion(GetLanguageVersionForTfm("net10.0") ?? LanguageVersion.Latest);
+        }
+
+        this.generator = this.CreateGenerator(new GeneratorOptions
+        {
+            AllowMarshaling = true,
+            ComInterop = new GeneratorOptions.ComInteropOptions { UseComSourceGenerators = useComSourceGenerators },
+        });
+        Assert.True(this.generator.TryGenerate("ID3D12Device", CancellationToken.None));
+        this.CollectGeneratedCode(this.generator);
+        this.AssertNoDiagnostics(
+            this.compilation,
+            logAllGeneratedCode: false,
+            acceptable: d => useComSourceGenerators && (d.Id is "CS8795" or "CS1574"));
+
+        List<MethodDeclarationSyntax> genericOverloads = this.FindGeneratedMethod(methodName)
+            .Where(m => m.TypeParameterList?.Parameters.Count == 1
+                && m.ParameterList.Parameters.FirstOrDefault() is { } first
+                && first.Modifiers.Any(SyntaxKind.ThisKeyword)
+                && first.Type?.ToString().Contains("ID3D12Device") == true)
+            .ToList();
+
+        Assert.Contains(genericOverloads, m =>
+            IsClassConstrainedGeneric(m)
+            && m.ParameterList.Parameters.All(p => p.Identifier.ValueText != "riidResource")
+            && m.ParameterList.Parameters.Last() is { Identifier.ValueText: "ppvResource", Type: IdentifierNameSyntax { Identifier.ValueText: "T" } } ppv
+            && ppv.Modifiers.Any(SyntaxKind.OutKeyword));
+    }
+
     /// <summary>
     /// Regression test for <see href="https://github.com/microsoft/CsWin32/issues/374">#374</see>.
     /// IMoniker.BindToObject should get a generic overload.
@@ -1096,6 +1136,9 @@ public void COMStructWrappers_ClsPragmaSuppressionsAreLoadBearing_Issue1703()
     private static string StripWarningDisablePragmas(string code) =>
         string.Join("\n", code.Split('\n').Where(line => !line.TrimStart().StartsWith("#pragma warning disable", StringComparison.Ordinal)));
 
+    private static bool IsClassConstrainedGeneric(MethodDeclarationSyntax method) =>
+        method.ConstraintClauses.Any(cc => cc.Constraints.Any(c => c is ClassOrStructConstraintSyntax { ClassOrStructKeyword.RawKind: (int)SyntaxKind.ClassKeyword }));
+
     private static string? GetDocumentationComment(MemberDeclarationSyntax member) =>
         member.GetLeadingTrivia()
             .Select(t => t.GetStructure())