Run tests with GCC backend

[GuillaumeGomez]

Part of rust-lang/compiler-team#891.

r? @Kobzol

[Kobzol]

We can also specify the doc_url of the job (

rust/src/ci/github-actions/jobs.yml

Line 345 in 5d41f7c

doc_url: https://rustc-dev-guide.rust-lang.org/tests/rust-for-linux.html

) to this: https://rustc-dev-guide.rust-lang.org/tests/codegen-backend-tests/cg_gcc.html

[GuillaumeGomez]

Error in ui tests:

2025-09-10T20:29:55.1757480Z -	error: couldn't load codegen backend /checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/codegen-backends/librustc_codegen_gcc-1.91.0-nightly.so: libgccjit.so.0: cannot open shared object file: No such file or directory
2025-09-10T20:29:55.1758929Z +	error: couldn't load codegen backend $BUILD_DIR/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/codegen-backends/librustc_codegen_gcc-1.91.0-nightly.so: libgccjit.so.0: cannot open shared object file: No such file or directory

Seems like something went wrong with the build/install of libgccjit. Any idea @Kobzol? I thought libgccjit was built with bootstrap if download-ci-gcc was set to false but maybe I misunderstood something.

[tgross35]

Is the .so actually in the load path? For some reason the GCC backend works differently than clif for me locally and I often find I need to manually append LD_LIBRARY_PATH, wonder if it could be something similar here.

[GuillaumeGomez]

Arf, it's the usual case of "it works locally for me". :-/

Gonna try to investigate if it's something wrong with paths.

[GuillaumeGomez]

Seems like we don't copy the .so files when we build gcc unlike when we download it.

[rustbot]

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.