SafeHandle generation for NTSTATUS-returning release method doesn't find constants across multiple ProjectionMetadataWinmd inputs

[MasonBergstrom]

Actual behavior

When generating a SafeHandle for a handle type whose release method returns NTSTATUS, CsWin32 fails during source generation:

PInvoke000: An internal error occurred: Failed while generating extern method: MySubscribeFunction.
Failed while generating SafeHandle for MyReleaseFunction.
Unable to find expected constant: STATUS_SUCCESS.

This occurs when the release method is defined in a custom ProjectionMetadataWinmd, while STATUS_SUCCESS is defined in the standard Win32Metadata winmd. Both winmds are loaded as ProjectionMetadataWinmd items.

In Generator.Handle.cs, the case "NTSTATUS" block calls this.TryGenerateConstantOrThrow("STATUS_SUCCESS") on the individual Generator instance, which only searches its own MetadataIndex. SuperGenerator provides cross-metadata search for types, methods, and enums,
but not for constants — so STATUS_SUCCESS from Win32Metadata is invisible during SafeHandle generation.

Expected behavior

CsWin32 should find STATUS_SUCCESS in Win32Metadata when generating a SafeHandle, since it's loaded as a ProjectionMetadataWinmd input alongside the custom winmd.

Repro steps

1. NativeMethods.txt content:

   MyReleaseFunction

2. NativeMethods.json content (if present):

    {
      "$schema": "https://aka.ms/CsWin32.schema.json",
      "emitSingleFile": true
    }

3. Any of your own code that should be shared?

   Create a custom winmd (via WinmdGenerator) containing:

   • A handle typedef mapped via autoTypes.json with a release method that returns NTSTATUS
   • Do NOT define STATUS_SUCCESS in the custom winmd

   Reference both the custom winmd and Win32Metadata as ProjectionMetadataWinmd items in the consuming project:

   Workaround: Define STATUS_SUCCESS in the custom winmd's source header so it gets scraped into the custom winmd:

   #ifndef STATUS_SUCCESS
   #define STATUS_SUCCESS ((NTSTATUS)0x00000000L)
   #endif

Context

• CsWin32 version: 0.3.213 and 0.3.269 (both reproduce)
• Win32Metadata version: default (via CsWin32 dependency)
• Target Framework: netstandard2.0
• LangVersion: not explicitly set

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This issue was drafted with the assistance of GitHub Copilot.