https://github.com/cpg314/cargo-workspace-unused-pub
Detect unused pub methods in a Rust workspace
https://github.com/cpg314/cargo-workspace-unused-pub
cargo lint rust unused-code
Last synced: 10 months ago
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Detect unused pub methods in a Rust workspace
- Host: GitHub
- URL: https://github.com/cpg314/cargo-workspace-unused-pub
- Owner: cpg314
- License: apache-2.0
- Created: 2024-04-21T10:40:34.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2025-02-25T21:13:22.000Z (over 1 year ago)
- Last Synced: 2025-09-20T14:23:21.311Z (10 months ago)
- Topics: cargo, lint, rust, unused-code
- Language: Rust
- Homepage: https://c.pgdm.ch/code
- Size: 18.6 KB
- Stars: 40
- Watchers: 3
- Forks: 1
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# cargo-workspace-unused-pub
This cargo subcommand tries to detect `pub` methods that are unused in an entire workspace, by performing workspace-wide analysis.
The [`dead_code` Rust compiler lint](https://doc.rust-lang.org/rust-by-example/attribute/unused.html) ignores `pub` methods, given that:
- The linter operates crate-by-crate.
- Unused `pub` methods could be used in another workspace crate, or be part of a public API.
See also the following discussions about this problem:
- https://github.com/rust-lang/rust-clippy/issues/5828 (closed as Clippy does not perform workspace-level analyses).
- https://users.rust-lang.org/t/would-pub-workspace-be-possible/105503/2
## Usage
```console
$ cargo workspace-unused-pub --help
Detect unused pub methods in a workspace
Usage: cargo workspace-unused-pub [OPTIONS] [WORKSPACE]
Arguments:
[WORKSPACE] [default: current workspace]
Options:
--scip
--extensions [default: rs,html]
-h, --help Print help
-V, --version Print version
```
## Implementation
Detection is performed in multiple phases:
1. Open [an SCIP code index](https://sourcegraph.com/blog/announcing-scip), or generate one with [rust-analyzer](https://rust-analyzer.github.io/).
```
Opened SCIP file with 806 documents
```
Note that the index generation can take a significant amount of time on large workspaces.
2. Record methods and traits declarations.
```
Found 6722 declarations and 286 traits
```
3. Phase 1: Find all methods that are seem never used. The following phases aim at removing false positives.
```
Pass 1: 1419 candidates
```
4. Phase 2: Remove false positives stemming from `main`, tests and trait methods.
```
Pass 2 (mains, tests, trait methods): 189 candidates
```
5. Phase 3: Perform a text search to remove false positives due to e.g. use in HTML templates:
```
Pass 3 (search): 43 candidates
Found 43 possibly unused functions
```
The extensions that are searched are defined by the `--extensions` flag.
6. Display results: \
The output of each phase (in the format above) can be viewed by setting the `RUST_LOG=debug` environment variable.
## Alternatives
- https://github.com/est31/warnalyzer. When `cargo-workspace-unused-pub` was developed, `warnalyzer` relied on the removed nightly `save-analysis` feature, and therefore required an older nightly compiler (see https://github.com/est31/warnalyzer/issues/9). This issue is now addressed, and `warnanalyzer` has a SCIP backend.
## TODO
- Automatically remove the unused functions (assuming a clean git repository is found).
- Build an approximate SCIP index with tree-sitter instead of rust-analyzer, for faster execution (e.g. in CI).
- Allow ignoring false positives with a special code comment or attribute.
- Support other objects than only methods (e.g. constants).
- Robustify the detection of test/main functions.