Tracking Issue for `-Z hint-mostly-unused`

This is a tracking issue for the compiler flag -Z hint-mostly-unused

About tracking issues

Tracking issues are used to record the overall progress of implementation.
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.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.
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Steps

• Open an MCP.
  • cf. https://github.com/rust-lang/compiler-team/issues/829
  • Superseded by https://github.com/rust-lang/compiler-team/issues/883
• Implement initially as an unstable compiler flag: https://github.com/rust-lang/rust/pull/135656
• Adjust documentation
  • Unstable book entry: https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/hint-mostly-unused.html
• Style updates for any new syntax (nightly-style-procedure) N/A
• Stabilization PR (see instructions on rustc-dev-guide)

Unresolved Questions

TODO

Implementation history

• https://github.com/rust-lang/rust/pull/135656

Start with the stabilization guide linked in this tracking issue and review the existing unstable book entry for -Z hint-mostly-unused. Check the completed implementation and documentation links, then prepare the stabilization PR requested by the remaining checklist item.