False positive regression for `unused_crate_dependencies`
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- Dominant language
- Rust
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Description
In beta (1.91.0-beta.3 (24bb93c38 2025-09-10)), there is a false positive from the unused_crate_dependencies lint that does not happen on 1.90.
To reproduce:
- clone https://github.com/unicode-org/icu4x at
292384d6a04746164faee7d660e75a5c7ca2b89c RUSTFLAGS="-D unused_crate_dependencies" cargo check --all-features --manifest-path components/properties/Cargo.toml- ✅
RUSTFLAGS="-D unused_crate_dependencies" cargo +beta check --all-features --manifest-path components/properties/Cargo.toml
error: extern crate `icu_locale_core` is unused in crate `icu_properties`
--> components/properties/src/lib.rs:5:1
|
5 | //! Definitions of [Unicode Properties] and APIs for
| ^
|
= help: remove the dependency or add `use icu_locale_core as _;` to the crate root
= note: requested on the command line with `-D unused-crate-dependencies`
error: could not compile `icu_properties` (lib) due to 1 previous error
This crate is used, so it's regression, not a bug fix.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Reproduce the regression with RUSTFLAGS="-D unused_crate_dependencies" cargo +beta check --all-features --manifest-path components/properties/Cargo.toml, comparing it with the non-beta command. Start from components/properties/src/lib.rs and the unused_crate_dependencies lint; done means the used icu_locale_core dependency is no longer reported while the lint still detects genuinely unused dependencies.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 48/100