Project IReference of TypeName/HResult as Type/Exception#2461
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Project IReference of TypeName/HResult as Type/Exception#2461Sergio0694 wants to merge 3 commits into
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Add members to TestComponentCSharp exercising the scalar IReference<T> projection for the two WinRT value types that map to .NET reference types: IReference<Windows.UI.Xaml.Interop.TypeName> -> System.Type and IReference<Windows.Foundation.HResult> -> System.Exception. Each adds a native-boxed property (BoxedTypeName / BoxedHResult) and a round-trip method (RoundtripTypeName / RoundtripHResult), with matching UnitTest coverage including the null case. These tests fail to build until the projection writer stops emitting the invalid Nullable<Type> / Nullable<Exception> for these instantiations. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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…able<> Windows.UI.Xaml.Interop.TypeName and Windows.Foundation.HResult are Windows Runtime value types that project to the .NET reference types System.Type and System.Exception. IReference<T> of those must project to the inner type directly (Type / Exception), not the invalid System.Nullable<Type/Exception> (the type argument of Nullable<T> must be a non-nullable value type). Generalize the TypedefNameWriter IReference special-case to drop the Nullable<> wrapper whenever the inner argument projects to a .NET reference type (TypeName -> Type, HResult -> Exception, or a literal System.Type). The runtime marshalling was already in place (TypeMarshaller / ExceptionMarshaller BoxToUnmanaged / UnboxToManaged); only the projected type name was wrong. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Add IVector<IReference<TypeName>> and IVector<IReference<HResult>> members to TestComponentCSharp (return and parameter, exercised in isolation) plus matching UnitTest coverage, to verify the generic projection compiles and to capture the runtime round-trip behavior. The public type collapses to IList<Type> / IList<Exception> via the scalar fix, while the ABI marshaller keeps the Nullable<T> element marker and so targets the IVector<IReference<T>> IID with per-element box/unbox. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Summary
Fix the C# projection of
IReference<T>for the two Windows Runtime value types that map to .NET reference types:Windows.UI.Xaml.Interop.TypeName->System.TypeandWindows.Foundation.HResult->System.Exception. These now project toType/Exceptioninstead of the invalidSystem.Nullable<Type>/System.Nullable<Exception>.Motivation
IReference<T>normally projects toSystem.Nullable<T>, which is correct for value-type inners. ButTypeNameandHResultare Windows Runtime value types that project to the .NET reference typesSystem.TypeandSystem.Exception.Nullable<Type>/Nullable<Exception>are not valid C# (the type argument ofNullable<T>must be a non-nullable value type), so any metadata containingIReference<TypeName>orIReference<HResult>produced a projection that failed to compile. A reference type is already nullable, so the projection should simply be the inner type. This mirrors the equivalent CsWinRT 2.x fix (#2103).The marshalling itself was already fully supported by the runtime (
TypeMarshaller/ExceptionMarshallerBoxToUnmanaged/UnboxToManagedviaIID_IReferenceOfType/IID_IReferenceOfException); only the projected type name was wrong.Changes
src/WinRT.Projection.Writer/Helpers/TypedefNameWriter.cs: when projectingWindows.Foundation.IReference<T>, detect inners whose projection is a .NET reference type (TypeName->Type,HResult->Exception, plus a literalSystem.Type) and emit the inner type directly instead of wrapping it inSystem.Nullable<>.src/Tests/TestComponentCSharp/(TestComponentCSharp.idl,Class.h,Class.cpp): add scalarIReference<TypeName>andIReference<HResult>members - a native-boxed property (BoxedTypeName/BoxedHResult) and a round-trip method (RoundtripTypeName/RoundtripHResult).src/Tests/UnitTest/TestComponentCSharp_Tests.cs: addReferenceTypeNameProjectsAsTypeandReferenceHResultProjectsAsException, covering both marshalling directions and the null case.Notes
The test members and the projection-writer fix are committed separately so CI can demonstrate the tests failing to build (invalid
Nullable<Type>/Nullable<Exception>) before the fix lands, then passing afterward. Collections of these types (IVector<IReference<TypeName>>etc.) are intentionally out of scope: sinceType/Exceptionare reference types there is no distinctNullable<>managed shape, so such a collection is indistinguishable fromIVector<TypeName>/IVector<HResult>at the interop layer.