[ComInterfaceGenerator] Trailing trivia after GeneratedComInterfaceAttribute included in generated files #88798
Description
Consider the following declaration of an interface designed to be multi-targeted against .NET 8 and earlier versions of .NET
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
[Guid("7DAC8207-D3AE-4C75-9B67-92801A497D44")]
#if !GENERATED_MARSHALLING
[ComImport]
#else
[GeneratedComInterface]
#endif
public partial interface IFoo
{
void Foo();
}Attempting to compile this results in the following error:
error CS1028: Unexpected preprocessor directive
In the generated source code, we can see the #ifdef directive has erroneously been carried over to two locations
// MyProject.IFoo.cs
namespace MyProject
{
[System.Runtime.InteropServices.Marshalling.IUnknownDerivedAttribute<InterfaceInformation, InterfaceImplementation>]
#endif
public partial interface IFoo
{
}
}
namespace MyProject
{
#endif
public partial interface IFoo
{
}
}If we flip our #if directive around to the following
#if GENERATED_MARSHALLING
[GeneratedComInterface]
#else
[ComImport]
#endif
public partial interface IFoothen the #else, [ComImport] and #endif lines are all copied over to the generated source file.
You can "work around" this by moving the interface header into the #if statement, as follows
#if !GENERATED_MARSHALLING
[ComImport]
public partial interface IFoo
#else
[GeneratedComInterface]
public partial interface IFoo
#endifHowever I would present that users attempting to multi-target by applying an #if around which attribute to use is a reasonable scenario; I would imagine upon reading the GeneratedComInterfaceAttribute AttributeSyntax the source generator should just trim all trailing trivia