Support Go modules for gccgo compilers

[partouf]

The go_library_builder.py currently skips gccgo compilers because modules don't work with our GCC installations.

Root Cause

The go tool bundled with gccgo has hardcoded build staging paths that don't exist in the deployed environment:

$ GOROOT=/opt/compiler-explorer/gcc-14.2.0 LD_LIBRARY_PATH=/opt/compiler-explorer/gcc-14.2.0/lib64 \
  /opt/compiler-explorer/gcc-14.2.0/bin/go build .
cmd/go: gccgo: exec: "/opt/compiler-explorer/gcc-build/staging/bin/gccgo": stat /opt/compiler-explorer/gcc-build/staging/bin/gccgo: no such file or directory

The go binary works for basic operations but looks for gccgo at the original build path rather than the installation path.

Potential Solutions

1. Rebuild GCC with correct installation paths (configure --prefix to match deployment location)
2. Build a wrapper script that sets up the environment correctly
3. Patch the go binary post-build to fix the hardcoded paths

References

• gccgo does support modules when properly configured: https://forum.golangbridge.org/t/building-modules-with-gccgo/17522
• Current skip list in go_library_builder.py: SKIP_COMPILERS = ["gotip", "go-tip", "gccgo"]

[partouf]

The fix likely needs to go in https://github.com/compiler-explorer/gcc-builder/blob/main/build/build.sh

Currently it builds with:

STAGING_DIR=$(pwd)/staging
--prefix="${STAGING_DIR}"

The gccgo go tool gets this staging path baked in. Options:

1. Use final prefix - Build with --prefix=/opt/compiler-explorer/gcc-${VERSION} since CE uses predictable paths
2. GOROOT_FINAL - The standard Go toolchain supports building in one location and deploying to another via $GOROOT_FINAL, but unclear if gccgo respects this
3. Post-build sed - Patch the binary to replace staging paths with final paths before tarball creation

Option 1 is probably cleanest if it doesn't break other aspects of the build.

[TechWizard9999]

Hi @partouf

I'd love to work on this issue. Is it still open for contribution?

Also, are there any channels (like Slack or Discord) where contributors usually discuss approaches or ask questions? I’d appreciate any help or guidance as I work through this.

Thanks in advance!

[partouf]

because the Go modules are still under construction, let's hold off on this for now

[TechWizard9999]

Hi @partouf,

I'm interested in contributing to the project and would like to gain a deeper understanding of the codebase. Are there any open issues suitable for newcomers that I could work on?
Thanks in Advance