Add rlib digest to identify Rust object files

[mehdiakiki]

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This adds a metadata entry to rlib archives that lists which members are Rust object files instead of relying on the filename heuristic in looks_like_rust_object.file. I also added a fallback to the old behavior for rlibs built by older compilers.

Part of #138243.

[rustbot]

r? @mati865

rustbot has assigned @mati865.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

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Why was this reviewer chosen?

The reviewer was selected based on:

• Owners of files modified in this PR: codegen, compiler
• codegen, compiler expanded to 69 candidates
• Random selection from 11 candidates

[mati865]

Got too much on my plate already.

@rustbot reroll

[mehdiakiki]

Will address the review comments by tomorrow!

[rustbot]

Some changes occurred in compiler/rustc_codegen_gcc

cc @antoyo, @GuillaumeGomez

[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.

[mehdiakiki]

Ok will complete the name changes today.

[mehdiakiki]

@rustbot ready

[petrochenkov]

@bors r+

[rust-bors]

📌 Commit 9606b0b has been approved by petrochenkov

It is now in the queue for this repository.

[rust-log-analyzer]

The job x86_64-gnu-llvm-21-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

test expr_store::tests::body::async_fn_weird_param_patterns ... ok
test expr_store::scope::tests::while_let_adds_binding ... ok
test expr_store::tests::body::array_element_cfg ... ok
test expr_store::tests::body::block::inner_item_smoke ... ok
error: test failed, to rerun pass `-p hir-def --lib`

Caused by:
  process didn't exit successfully: `/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/hir_def-c439368f2b64a049 '--skip=tests::smoke_test_real_sysroot_cargo' --skip=check_code_formatting -Z unstable-options --format json` (signal: 11, SIGSEGV: invalid memory reference)
Bootstrap failed while executing `--stage 2 test --skip tests --skip coverage-map --skip coverage-run --skip library --skip tidyselftest`
Build completed unsuccessfully in 1:01:16
  local time: Tue May  5 12:54:17 UTC 2026
  network time: Tue, 05 May 2026 12:54:18 GMT
##[error]Process completed with exit code 1.

[rust-bors]

💔 Test for ee26d47 failed: CI. Failed job:

• auto - x86_64-gnu-llvm-21-1 (web logs, enhanced plaintext logs)

[JonathanBrouwer]

@bors retry

[rust-bors]

☀️ Test successful - CI
Approved by: petrochenkov
Duration: 3h 8m 44s
Pushing 740679e to main...

[github-actions]

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing 4feb722 (parent) -> 740679e (this PR)

Test differences

Show 2 test diffs

2 doctest diffs were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 740679e1f5554a3c1695317e084809e3fceb9825 --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

1. test-various: 1h 29m -> 1h 56m (+31.4%)
2. dist-x86_64-msvc-alt: 2h 8m -> 2h 42m (+25.9%)
3. x86_64-msvc-2: 2h 33m -> 2h (-21.6%)
4. x86_64-gnu-debug: 1h 55m -> 1h 30m (-21.4%)
5. dist-powerpc64le-linux-gnu: 1h 34m -> 1h 16m (-19.5%)
6. dist-armhf-linux: 1h 28m -> 1h 11m (-18.8%)
7. dist-loongarch64-musl: 1h 47m -> 1h 28m (-17.9%)
8. dist-x86_64-musl: 2h 11m -> 1h 48m (-17.5%)
9. dist-i686-msvc: 2h 22m -> 1h 59m (-16.3%)
10. dist-x86_64-netbsd: 1h 22m -> 1h 10m (-14.9%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

[rust-timer]

Finished benchmarking commit (740679e): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.4%	[0.3%, 0.6%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -2.2%, secondary 0.8%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.8%	[0.6%, 0.9%]	2
Improvements ✅ (primary)	-2.2%	[-2.2%, -2.2%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.2%	[-2.2%, -2.2%]	1

Cycles

Results (primary 0.1%, secondary 0.8%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.3%	[2.3%, 2.3%]	1
Regressions ❌ (secondary)	1.2%	[0.5%, 2.5%]	6
Improvements ✅ (primary)	-2.1%	[-2.1%, -2.1%]	1
Improvements ✅ (secondary)	-0.5%	[-0.6%, -0.4%]	2
All ❌✅ (primary)	0.1%	[-2.1%, 2.3%]	2

Binary size

Results (primary 0.1%, secondary 0.7%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	0.1%	[0.0%, 0.2%]	65
Regressions ❌ (secondary)	0.7%	[0.0%, 4.1%]	84
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[0.0%, 0.2%]	65

Bootstrap: 495.518s -> 495.494s (-0.00%)
Artifact size: 394.42 MiB -> 394.42 MiB (0.00%)