remap OUT_DIR paths to fix build script path leakage in crate metadata. by paradoxicalguy · Pull Request #155935 · rust-lang/rust

paradoxicalguy · 2026-04-28T15:42:49Z

problem:

build script outputs (OUT_DIR) leak absolute paths into crate metadata causing non-determinism across identical builds.
bootstrap remaps source paths (self.build.src) and registry sources but doesn't not remap self.build.out used by OUT_DIR

fix:

adding --remap-path-prefix for self.build.out , mapping it to a stable virtual prefix, consistent with existing remappings

result:

removes path-based non-determinism from build script outputs
verified via stage 2 reproducibility testing.

r? @Urgau

Urgau

Looks good to me.

View changes since this review

Urgau · 2026-04-28T16:52:04Z

r=me once the typo is resolved and CI is happy

@bors delegate+

rust-bors · 2026-04-28T16:52:07Z

✌️ @paradoxicalguy, you can now approve this pull request!

If @Urgau told you to "r=me" after making some further change, then please make that change and post @bors r=Urgau.

View changes since this delegation.

…tifacts

paradoxicalguy · 2026-04-28T17:01:54Z

i was not able to find what the problem was 😭
thanks, changed and pushed again

Co-authored-by: bjorn3 <17426603+bjorn3@users.noreply.github.com>

Urgau · 2026-04-28T17:05:36Z

i was not able to find what the problem was 😭

Yeah, the backtrace is a red herring, I've asked for it to be removed when tidy fails, #t-infra/bootstrap > Stop priting a backtrace when tidy failed @ 💬.

paradoxicalguy · 2026-04-28T19:22:49Z

@bors r=Urgau, all CI tests green

rust-bors · 2026-04-28T19:22:52Z

📌 Commit 26ce8a9 has been approved by Urgau,

It is now in the queue for this repository.

⚠️ The following reviewer(s) could not be found: ``

🌲 The tree is currently closed for pull requests below priority 1000. This pull request will be tested once the tree is reopened.

@Urgau

remap OUT_DIR paths to fix build script path leakage in crate metadata. ### problem: - build script outputs (`OUT_DIR`) leak absolute paths into crate metadata causing non-determinism across identical builds. - bootstrap remaps source paths (`self.build.src`) and registry sources but doesn't not remap `self.build.out` used by `OUT_DIR` ### fix: - adding `--remap-path-prefix` for `self.build.out` , mapping it to a stable virtual prefix, consistent with existing remappings ### result: - removes path-based non-determinism from build script outputs - verified via stage 2 reproducibility testing. r? @Urgau

rust-bors · 2026-04-28T23:13:29Z

💔 Test for a6fbdb7 failed: CI. Failed job:

auto - x86_64-gnu-distcheck (web logs, enhanced plaintext logs)

Urgau · 2026-04-29T05:31:39Z

Seems spurious.

@bors retry

@Urgau

…r=Urgau, remap OUT_DIR paths to fix build script path leakage in crate metadata. ### problem: - build script outputs (`OUT_DIR`) leak absolute paths into crate metadata causing non-determinism across identical builds. - bootstrap remaps source paths (`self.build.src`) and registry sources but doesn't not remap `self.build.out` used by `OUT_DIR` ### fix: - adding `--remap-path-prefix` for `self.build.out` , mapping it to a stable virtual prefix, consistent with existing remappings ### result: - removes path-based non-determinism from build script outputs - verified via stage 2 reproducibility testing. r? @Urgau

@Urgau

…r=Urgau, remap OUT_DIR paths to fix build script path leakage in crate metadata. ### problem: - build script outputs (`OUT_DIR`) leak absolute paths into crate metadata causing non-determinism across identical builds. - bootstrap remaps source paths (`self.build.src`) and registry sources but doesn't not remap `self.build.out` used by `OUT_DIR` ### fix: - adding `--remap-path-prefix` for `self.build.out` , mapping it to a stable virtual prefix, consistent with existing remappings ### result: - removes path-based non-determinism from build script outputs - verified via stage 2 reproducibility testing. r? @Urgau

Rollup of 9 pull requests Successful merges: - #151742 (Remove redundant information in `rustc_abi::Variants`) - #155856 (std_detect: support detecting more features on aarch64 Windows) - #155861 (Suggest `[const] Trait` bounds in more places) - #155899 (`dlltool`: Set the working directory to workaround `--temp-prefix` bug) - #155916 (Update with new LLVM 22 target for `wasm32-wali-linux-musl` target) - #155935 (remap OUT_DIR paths to fix build script path leakage in crate metadata. ) - #155950 (use the new `//@ needs-asm-mnemonic: ret` more) - #155949 (Update `opt_ast_lowering_delayed_lints` query to allow "stealing" lints, allowing to use `FnOnce` instead of `Fn`) - #155951 (Make `FlatMapInPlaceVec` an unsafe trait.)

@Urgau

…r=Urgau, remap OUT_DIR paths to fix build script path leakage in crate metadata. ### problem: - build script outputs (`OUT_DIR`) leak absolute paths into crate metadata causing non-determinism across identical builds. - bootstrap remaps source paths (`self.build.src`) and registry sources but doesn't not remap `self.build.out` used by `OUT_DIR` ### fix: - adding `--remap-path-prefix` for `self.build.out` , mapping it to a stable virtual prefix, consistent with existing remappings ### result: - removes path-based non-determinism from build script outputs - verified via stage 2 reproducibility testing. r? @Urgau

paradoxicalguy · 2026-04-29T14:14:54Z

is there any issue regarding merge/rollups?

Urgau · 2026-04-29T16:06:53Z

is there any issue regarding merge/rollups?

Not that I know of, this PR is currently being tested in #155964. It can take up to a few days for a PR to be merged, our CI is not very fast and we have a bunch of PRs to merge.

paradoxicalguy · 2026-04-29T16:45:58Z

is there any issue regarding merge/rollups?

Not that I know of, this PR is currently being tested in #155964. It can take up to a few days for a PR to be merged, our CI is not very fast and we have a bunch of PRs to merge.

understandable, i was asking in addition to bors build failing too, this pr's and last rollup's, both.

…uwer Rollup of 12 pull requests Successful merges: - #155189 (simd_reduce_min/max: remove float support) - #155721 (When archive format is wrong produce an error instead of ICE) - #155794 (privacy: share effective visibility initialization) - #155856 (std_detect: support detecting more features on aarch64 Windows) - #155861 (Suggest `[const] Trait` bounds in more places) - #155899 (`dlltool`: Set the working directory to workaround `--temp-prefix` bug) - #155916 (Update with new LLVM 22 target for `wasm32-wali-linux-musl` target) - #155935 (remap OUT_DIR paths to fix build script path leakage in crate metadata. ) - #155950 (use the new `//@ needs-asm-mnemonic: ret` more) - #155958 (ci(free-disk-space): remove more tools and fix warnings) - #155949 (Update `opt_ast_lowering_delayed_lints` query to allow "stealing" lints, allowing to use `FnOnce` instead of `Fn`) - #155951 (Make `FlatMapInPlaceVec` an unsafe trait.)

@Urgau

…r=Urgau, remap OUT_DIR paths to fix build script path leakage in crate metadata. ### problem: - build script outputs (`OUT_DIR`) leak absolute paths into crate metadata causing non-determinism across identical builds. - bootstrap remaps source paths (`self.build.src`) and registry sources but doesn't not remap `self.build.out` used by `OUT_DIR` ### fix: - adding `--remap-path-prefix` for `self.build.out` , mapping it to a stable virtual prefix, consistent with existing remappings ### result: - removes path-based non-determinism from build script outputs - verified via stage 2 reproducibility testing. r? @Urgau

rustbot assigned Urgau Apr 28, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-bootstrap Relevant to the bootstrap subteam: Rust's build system (x.py and src/bootstrap) labels Apr 28, 2026

paradoxicalguy force-pushed the fix-out-dir-remap branch from acad38e to 1f2c826 Compare April 28, 2026 15:58

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Urgau approved these changes Apr 28, 2026

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bootstrap: remap OUT_DIR paths to fix build script path leakage in ar…

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paradoxicalguy force-pushed the fix-out-dir-remap branch from 1f2c826 to e743a4d Compare April 28, 2026 16:59

bjorn3 reviewed Apr 28, 2026

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Comment thread src/bootstrap/src/core/builder/cargo.rs Outdated

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26ce8a9

Co-authored-by: bjorn3 <17426603+bjorn3@users.noreply.github.com>

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rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 29, 2026

jhpratt mentioned this pull request Apr 29, 2026

Rollup of 7 pull requests #155956

Closed

jhpratt mentioned this pull request Apr 29, 2026

Rollup of 9 pull requests #155960

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JonathanBrouwer mentioned this pull request Apr 29, 2026

Rollup of 12 pull requests #155964

Closed

JonathanBrouwer mentioned this pull request Apr 29, 2026

Rollup of 22 pull requests #155976

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paradoxicalguy commented Apr 28, 2026

problem:

fix:

result:

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