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docs(guide): Point out tools for reducing dependencies #16078

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18 changes: 18 additions & 0 deletions src/doc/src/guide/build-performance.md
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Expand Up @@ -86,6 +86,24 @@ Trade-offs:
- ✅ Faster build times
- ❌ **Requires using nightly Rust and an [unstable Rust feature][parallel-frontend-issue]**

## Reducing built code

### Removing unused dependencies

Recommendation: Periodically review unused dependencies for removal using third-party tools like
[cargo-machete](https://crates.io/crates/cargo-machete),
[cargo-udeps](https://crates.io/crates/cargo-udeps),
[cargo-shear](https://crates.io/crates/cargo-shear).

When changing code,
it can be easy to miss that a dependency is no longer used and can be removed.

> *Note:* native support for this in Cargo is being tracked in [#15813](https://github.com/rust-lang/cargo/issues/15813).
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nit: We normally use bold for note


Trade-offs:
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I'm not sure how much the trade-offs section makes sense here, as it's not a config that you would apply and it then affects your crate, but rather you just use a tool that might have false negatives/positives, and that's about it. But I also don't think it's super important.

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It provided a nice place to

  • Call out the benefits
  • Call out false positives and false negatives

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Sure, fair enough :)

- ✅ Faster full build and link times
- ❌ May incorrectly flag dependencies as unused or miss some

[parallel-frontend-blog]: https://blog.rust-lang.org/2023/11/09/parallel-rustc/
[parallel-frontend-issue]: https://github.com/rust-lang/rust/issues/113349
[build.rustflags]: ../reference/config.md#buildrustflags