Fix WinForms stackTrace E_NOINTERFACE by tolerating non-IL managed frames

[govert]

Fixes #215

AHub link

N/A

Summary

This change prevents stackTrace from failing with 0x80004002 when a managed frame does not expose ICorDebugILFrame (observed in WinForms load-event call paths).

Root cause

WalkFrames() treated a failed IID_ICorDebugILFrame QI as fatal for managed frames. In the failing WinForms path, that QI fails for some frames, and the whole stack walk aborted.

Fix

In src/debugger/frames.cpp:

• If IID_ICorDebugILFrame QI fails, do not return failure.
• Try IID_ICorDebugInternalFrame and emit FrameCLRInternal when available.
• Otherwise emit FrameUnknown.
• Continue walking remaining frames.

This keeps stackTrace successful while preserving frame visibility.

Tests

Added a targeted regression test:

• test-suite/VSCodeTestStackTraceWinForms
• helper target app test-suite/TestAppWinFormsStackTrace

The test:

1. Launches WinForms target.
2. Breaks in constructor (Form1), asserts stackTrace success.
3. Continues to Form1_Load, asserts stackTrace success on the previously failing path.
4. Terminates/disconnects cleanly.

Registered in:

• test-suite/run_tests.ps1
• test-suite/run_tests.sh
• test-suite/sdb_run_tests.ps1
• test-suite/sdb_run_tests.sh

Local verification

Ran:

dotnet run --project TestRunner -- --local ../bin/netcoredbg.exe --proto vscode --test VSCodeTestStackTraceWinForms --sources VSCodeTestStackTraceWinForms/Program.cs --assembly VSCodeTestStackTraceWinForms/bin/Debug/netcoreapp3.1/VSCodeTestStackTraceWinForms.dll

Result: Success: Test case "VSCodeTestStackTraceWinForms" is passed!!!

Posted by Codex on behalf of @govert.

[viewizard]

Thanks! I just check this fix manually, changes in debugger's code looks good for me. Will move this PR into our internal CI for testing.

[21Beagle]

Hi, can I politely ask if is there any update on this? I am finding myself coming back here daily to see if this has been added to the latest version of netcoredbg

Thanks

[gbalykov]

@21Beagle this looks good. We've moved this to internal repo, will be part of next release here (probably in May). For now, as a workaround you can build from source code.