Stabilize --remap-path-prefix in rustdoc

[Urgau]

Stabilization report of --remap-path-prefix in rustdoc

Summary

rustc supports remapping source paths prefixes as a best effort in all compiler generated output, including compiler diagnostics, debugging information, macro expansions, documentation, doctests, etc.

This is useful for normalizing build products, for example, by removing the current directory out of the paths emitted into object files.

This stabilization stabilize the same flag used by rustc in rustdoc.

There are no tracking issue.

Stabilization was discussed at the last meeting, #t-rustdoc/meetings > 2026-04-13 @ 💬.

What is stabilized

The rustdoc --remap-path-prefix flag is being stabilized by this PR. (It's equivalent to rustc flag)

It permits remapping (as a best effort) source path prefixes in all output, including diagnostics, debug information, macro expansions, generated documentation, etc.

It takes a value of the form FROM=TO where a path prefix equal to FROM is rewritten to the value TO.

Example

rustdoc src/lib.rs --remap-path-prefix="$PWD=/foo"

What isn't stabilized

Neither --remap-path-scope (soon to be added as unstable in rustdoc) or the already unstable in rustc documentation scope are being stabilized or added here.

Design

Implementation history

• rustdoc: Add support for --remap-path-prefix #107099

Unresolved questions

There are no unresolved questions.

Post-implementation changes

The implementation has evolved with rustc, but no changes to the flag it-self have been made.

Nightly extensions

The documentation scope, which currently can only be set from rustc, as we need to add an equivalent to the --remap-path-scope flag, which is planned, but not required, the current --remap-path-prefix defaults to the all scope, like rustc.

Doors closed

We are committing to having to having a flag that permits remapping paths. The compiler team already made the same commitment.

Feedback

Call for testing

No call for testing has been done.

Nightly use

Unable to determine. A GitHub search only seems to only reveals the rustc usage (over 6k though).

Rust-for-Linux is using the flag.

Implementation

Major parts

• rustdoc: Add support for --remap-path-prefix #107099
• Overhaul filename handling for cross-compiler consistency #149709
• Handle remapped paths correctly when generating "Source" links #150172
• Add a documentation remapping path scope for rustdoc usage #151589

Coverage

• tests/rustdoc-ui/remap-path-prefix-failed-doctest-output.rs
• tests/rustdoc-ui/remap-path-prefix-invalid-doctest.rs
• tests/rustdoc-ui/remap-path-prefix-macro.rs
• tests/rustdoc-ui/remap-path-prefix-passed-doctest-output.rs
• tests/rustdoc-ui/lints/remap-path-prefix-lint.rs
• tests/rustdoc-html/import-remapped-paths.rs
• tests/rustdoc-html/macro/external-macro-src.rs

Outstanding bugs

There are no outstanding bugs regarding --remap-path-prefix in rustdoc.

There are caveats and limitation in rustc, but they mostly concern generated object files, which we don't really have.

Outstanding FIXMEs

There are no FIXME regarding --remap-path-prefix.

Acknowledgments

• @edward-shen
• @Urgau

@rustbot labels +T-rustdoc +F-trim-paths
cc @ojeda (for Rust-for-Linux)
r? rustdoc

[GuillaumeGomez]

@rfcbot fcp merge rustdoc-internals

[rust-rfcbot]

Team member @GuillaumeGomez has proposed to merge this. The next step is review by the rest of the tagged team members:

• @GuillaumeGomez
• @Manishearth
• @Urgau
• @camelid
• @fmease
• @lolbinarycat
• @notriddle
• @yotamofek

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

[lolbinarycat]

there seems to be a bit of an issue in the description

The rustdoc --remap-path-scope flag is being stabilized by this PR. (It's equivalent to rustc flag)

Neither --remap-path-scope (soon to be added as unstable in rustdoc) or the already unstable in rustc documentation scope are being stabilized or added here.

[Urgau]

Sorry about that, I based this report on the one I did for the scope variant in the compiler. Fixed.

[rust-bors]

☔ The latest upstream changes (presumably #155380) made this pull request unmergeable. Please resolve the merge conflicts.