Add linker_static_archive_order lint for -Clink-arg archives placed before referenced dynamic libs

[cezarbbb]

See issue #154975

When a static archive is passed via -Clink-arg, rustc appends it after its own native libraries. With --as-needed, strict left-to-right linkers like GNU ld.bfd (unlike lld, which tolerates back-references) can then drop a dynamic library that only that archive references, leaving unresolved symbols.

rustc can't tell whether the back-reference actually exists without resolving the archive's symbols, so this is a heuristic lint rather than a fix to the ordering itself. It's Allow by default and carries ignore_deny_warnings, so it stays silent unless explicitly requested with -Wlinker-static-archive-order, and -D warnings won't promote a possible false positive into an error — only -Dlinker-static-archive-order will.

The lint fires for GNU ld-family linkers that don't use lld (bare ld or cc-driven), excluding Windows and Darwin where the --as-needed model doesn't apply. The diagnostic points at three workarounds: -l static=, -Zpre-link-arg=, and wrapping the dynamic library in --no-as-needed/--as-needed.

r? @bjorn3

[bjorn3]

I think we should only point to -l static. -Zpre-link-args is unstable and --no-as-needed wouldn't help with for exanple fixing libc references when libc is statically linked. Maybe we can emit it even with lld? That way you don't suddenly get surprises if you have to disable the lld default in the future for whatever reason.

[cezarbbb]

Maybe we can emit it even with lld? That way you don't suddenly get surprises if you have to disable the lld default in the future for whatever reason.

That makes sense. I'll do it.

[rustbot]

This PR was rebased onto a different main 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.

[bjorn3]

Passing static libraries using -Clink-arg rather than -l feels iffy to me even ignoring the symbol resolution order issue. Maybe put less emphasis on the exact issue and instead say that -Clink-arg for static libraries is not idiomatic and what way should be used instead. You can leave a note about -Clink-arg playing badly with symbol resolution order as a concrete example about why you should avoid it.

View changes since the review

[cezarbbb]

Rewrote the lint docs to lead with -Clink-arg not being the idiomatic way to pass static libraries and -l static= being the alternative, with the ordering issue kept as a concrete example.

[bjorn3]

Even if it isn't strictly needed, I think the lint should still fire.

View changes since the review

[cezarbbb]

OK.