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

[jieyouxu]

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. Add -C hint-mostly-unused option compiler-team#829
  • Superseded by Add -Z hint-mostly-unused option to hint that most of a crate's API surface will be unused compiler-team#883
• Implement initially as an unstable compiler flag: Add -Z hint-mostly-unused to tell rustc that most of a crate will go unused #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

• Add -Z hint-mostly-unused to tell rustc that most of a crate will go unused #135656