Tracking Issue for trim-paths RFC 3127

[ehuss]

Summary

RFC: #3127
Documentation: https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#profile-trim-paths-option
Issues: Z-trim-paths Nightly: path sanitization
rustc tracking issue: rust-lang/rust#111540

This adds a new profile setting (among other things) to control how paths are sanitized in the resulting binary.

Unresolved Issues

• Should make --remap-path-prefix work with rustdoc and doctest?
  • Yes as rustdoc supports both
    • rustdoc: Add support for --remap-path-prefix rust#107099
    • Fix rustdoc missing handling of remap-path-prefix option rust#128736
  • Integrate --remap-path-prefix in rustdoc invocations (cargo doc) feat(trim-paths): rustdoc supports trim-paths for diagnostics  #14389
  • Integrate --remap-path-prefix and -Zremap-path-scope in doctest (cargo test --doc)
• Determine the remap rules: trim-paths: Remap rules for different dependency kinds #13171
  • A cross-platform stable hash for CARGO_HOME layout?
    • On Windows the local path contains prefix component e.g.C:/, which essentially results in a different hash result from what on other platforms.
    • benchmark BLAKE3, BLAKE2s, and rustc-stable-hasher
      • See result in feat!: use stable hash from rustc-stable-hash #14116 (comment)
      • rustc-stable-hash is on par with the original siphash, while blake3 is 2-3x slower. The total spent in stable hashing for a cargo build invocation may be unimportant. It took 500μs-1500μs for buidling cargo itself.

Future Extensions

No response

About tracking issues

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They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
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Implementation history

• feat: implement RFC 3127 -Ztrim-paths #12625
• feat(trim-paths): set env CARGO_TRIM_PATHS for build scripts #12900
• fix: merge trim-paths from different profiles  #12908
• feat(trim-paths): rustdoc supports trim-paths for diagnostics  #14389

[epage]

Last status update I'm aware of

https://rust-lang.zulipchat.com/#narrow/stream/246057-t-cargo/topic/trim-paths.20testing/near/401425246

[joshtriplett]

Is this working on Linux, well enough that we could ship it for Linux without promising macOS support?

[weihanglo]

This is the latest status of it on rustc side: rust-lang/rust#111540 (comment), which the new remap rule in the conclusion is implemented. I've updated the unresolved issues section in this tracking issue.

[weihanglo]

Status update:

• This change rustdoc: Add support for --remap-path-prefix rust#107099 should make -Ztrim-paths also work for rustdoc
• A stable hasher extracting from rustc is on its way. See also
  • Extract rustc stable hasher into it's own crate compiler-team#755
  • Bootstrap the rustc-stable-hash crate rustc-stable-hash#1

[weihanglo]

rust-lang/rust#107099 is just merged, so should be able to support for rustdoc.

Edit: need to adjust cargo to pass --remap-path-prefix to rustdoc invocations.

[weihanglo]

Updated:

• doctest has supported remapping: Simplify trim-paths feature by merging all debuginfo options together rust#122450
• rustdoc diagnostics hasn't: rustdoc: use remap-path-prefix rust#69264 (comment)

That potentially blocks this, if we would like to see -Ztrim-paths supports also for rustdoc invocations.

[liciana24]

Updated:

• doctest has supported remapping: Simplify trim-paths feature by merging all debuginfo options together rust#122450
• rustdoc diagnostics hasn't: rustdoc: use remap-path-prefix rust#69264 (comment)

That potentially blocks this, if we would like to see -Ztrim-paths supports also for rustdoc invocations.

both of those linked are closed/merged what is left blocking to get trimpaths working?

[weihanglo]

both of those linked are closed/merged what is left blocking to get trimpaths working?

@liciana24 There are some unresolved issues listed in the PR description I just updated.

It should minimally work. Any feedback of it not working?

[lina9992006]

status?

[weihanglo]

@lina9992006
Just posted benchmark results here for different stable hash algorithms: #14116 (comment)

If you'd like to move this forward, here are areas we need helps:

• Resolving issues mentioned in the PR description.
• Testing out the current implementation and provide feedback.

[lina9992006]

why is hashing relevant here?

[weihanglo]

A stable cross-platform hash algorithm helps -Ztrim-paths finding sources from the same path when debugging. See #13171 (comment) and other comments around.