Add implicit IntPtr casts to void* typedefs (#1521)

* Add regression test

* Add helpers for void* typedefs

Author: jevansaks

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

@@ -173,6 +173,35 @@ private StructDeclarationSyntax DeclareTypeDefStruct(TypeDefinition typeDef, Typ
                     .WithSemicolonToken(SemicolonWithLineFeed));
             }
         }
+        else if (fieldInfo.FieldType is PointerTypeSyntax pts && IsVoid(pts.ElementType))
+        {
+            // void* typedefs should still get IntPtr conversions for convenience like their HANDLE counterparts.
+
+            // public static implicit operator IntPtr(PSID value) => new IntPtr(value.Value);
+            ExpressionSyntax valueValueArg = MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, valueParameter, fieldIdentifierName);
+            members = members.Add(ConversionOperatorDeclaration(Token(SyntaxKind.ImplicitKeyword), IntPtrTypeSyntax)
+                .AddParameterListParameters(Parameter(valueParameter.Identifier).WithType(name.WithTrailingTrivia(TriviaList(Space))))
+                .WithExpressionBody(ArrowExpressionClause(
+                    ObjectCreationExpression(IntPtrTypeSyntax).AddArgumentListArguments(Argument(valueValueArg))))
+                .AddModifiers(TokenWithSpace(SyntaxKind.PublicKeyword), TokenWithSpace(SyntaxKind.StaticKeyword)) // operators MUST be public
+                .WithSemicolonToken(SemicolonWithLineFeed));
+
+            // public static explicit operator PSID(IntPtr value) => new PSID(value.ToPointer());
+            members = members.Add(ConversionOperatorDeclaration(Token(SyntaxKind.ExplicitKeyword), name)
+                .AddParameterListParameters(Parameter(valueParameter.Identifier).WithType(IntPtrTypeSyntax.WithTrailingTrivia(TriviaList(Space))))
+                .WithExpressionBody(ArrowExpressionClause(ObjectCreationExpression(name).AddArgumentListArguments(
+                    Argument(CastExpression(fieldInfo.FieldType, InvocationExpression(MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, valueParameter, IdentifierName(nameof(IntPtr.ToPointer)))))))))
+                .AddModifiers(TokenWithSpace(SyntaxKind.PublicKeyword), TokenWithSpace(SyntaxKind.StaticKeyword)) // operators MUST be public
+                .WithSemicolonToken(SemicolonWithLineFeed));
+
+            // public static explicit operator PSID(UIntPtr value) => new PSID(value.ToPointer());
+            members = members.Add(ConversionOperatorDeclaration(Token(SyntaxKind.ExplicitKeyword), name)
+                .AddParameterListParameters(Parameter(valueParameter.Identifier).WithType(UIntPtrTypeSyntax.WithTrailingTrivia(TriviaList(Space))))
+                .WithExpressionBody(ArrowExpressionClause(ObjectCreationExpression(name).AddArgumentListArguments(
+                    Argument(CastExpression(fieldInfo.FieldType, InvocationExpression(MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, valueParameter, IdentifierName(nameof(IntPtr.ToPointer)))))))))
+                .AddModifiers(TokenWithSpace(SyntaxKind.PublicKeyword), TokenWithSpace(SyntaxKind.StaticKeyword)) // operators MUST be public
+                .WithSemicolonToken(SemicolonWithLineFeed));
+        }
 
         foreach (string alsoUsableForValue in this.GetAlsoUsableForValues(typeDef))
         {

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

@@ -156,4 +156,16 @@ public void ReleaseMethodGeneratedWithUncommonReturnType(string api)
     [Theory]
     [InlineData("HDC")]
     public void InterestingHandles(string api) => this.GenerateApi(api);
+
+    [Theory]
+    [InlineData("HWND")]
+    [InlineData("PSID")]
+    public void VerifyHandlesHaveImplicitIntPtrCast(string api)
+    {
+        this.GenerateApi(api);
+        BaseTypeDeclarationSyntax type = Assert.Single(this.FindGeneratedType(api));
+        IEnumerable<string> methods = type.DescendantNodes().OfType<ConversionOperatorDeclarationSyntax>()
+            .Select(x => x.Type).OfType<IdentifierNameSyntax>().Select(x => x.Identifier.ValueText);
+        Assert.Contains("IntPtr", methods);
+    }
 }