LLVM 21.1.0-rc3 breaks CGO cross-compilation for Windows ARM64

[yngvar]

Description

The latest docker-go-mingw image (using LLVM 21.1.0-rc3) fails to build Go applications with CGO for Windows ARM64 targets.

Error

cgo: cannot parse $WORK/b826/cgo.o as ELF, Mach-O, PE or XCOFF

Root Cause

Regression introduced in LLVM 21.1.0-rc3 (between v1.24.4 and v1.24.6 of your image).

Tested Versions

• ✅ v1.24.4 (LLVM 19.1.7) - Works
• ✅ LLVM 20.1.8 (manual test) - Works
• ❌ v1.24.6 (LLVM 21.1.0-rc3) - Fails

Recommendation

Downgrade to stable LLVM 20.1.8 until LLVM 21.1.0 final release fixes the CGO object file generation bug, which means reverting from LLVM-MinGW 20250812 to 20250709.

[x1unix]

@yngvar thank you for reporting the issue and suggesting a fix. I'll fix the image today.

[x1unix]

@yngvar I've re-pushed images for 1.24.6 and 1.25.0 with a correct llvm version 20250709.