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feat: Add -Zhint-msrv flag#17106

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feat: Add -Zhint-msrv flag#17106
clubby789 wants to merge 1 commit into
rust-lang:masterfrom
clubby789:lint-rust-version

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@clubby789 clubby789 commented Jun 16, 2026 •
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Pass -Zhint-msrv={package.rust-version} to rustc when -Zhint-msrv is passed to Cargo, and the rust-version field is set.
This flag was implemented at rust-lang/rust#157707, renamed in rust-lang/rust#158134

Tracking issue: rust-lang/rust#157574

@rustbot rustbot added the A-build-execution Area: anything dealing with executing the compiler label Jun 16, 2026
@rustbot rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 16, 2026
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rustbot commented Jun 16, 2026

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Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @weihanglo (or someone else) some time within the next two weeks.

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@clubby789 clubby789 force-pushed the lint-rust-version branch from 2486c65 to 701d42c Compare June 16, 2026 11:02
epage
epage reviewed Jun 16, 2026
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Comment thread src/cargo/core/compiler/mod.rs Outdated
}

if let Some(version) = unit.pkg.manifest().rust_version()
&& bcx.gctx.nightly_features_allowed

@epage epage Jun 16, 2026 •
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I don't think we normally implicitly opt-in to unstable features based on the channel (note the name "allowed"). If/when we do, it is part of pre-stabilization.

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@clubby789 clubby789 Jun 16, 2026 •
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I could put this behind a cargo unstable flag, the only worry would be that that wouldn't result in a lot of real world testing of the flag.

@weihanglo weihanglo Jun 17, 2026

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the only worry would be that that wouldn't result in a lot of real world testing of the flag.

That is a valid concern, as this is less likely a flag people would opt-in. I knew you implemented it. How confident are you in the implementation and do we have a clear schedule of incoming stabilization?

The other approach we have is crater run. While the actual lint report varies, crater at least ensure things is not broken.

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The implementation is reasonably simple. I think the main concerns WRT stabilisation would be

  • Applying MSRV to a wider set of lints
  • More discussion around the exact semantics of the flag (i.e. the linked comment in the tracking issue)

@epage epage Jun 17, 2026

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Encouraging use of this through config would make it easier for more people to opt-in

@clubby789 clubby789 force-pushed the lint-rust-version branch from 701d42c to 96724af Compare June 16, 2026 12:11
@rustbot rustbot added the A-unstable Area: nightly unstable support label Jun 16, 2026
@clubby789 clubby789 changed the title feat: Set -Zlint-rust-version on nightly feat: Add -Zlint-rust-version flag Jun 16, 2026
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Comment thread src/cargo/core/features.rs Outdated
@rustbot rustbot added the A-documenting-cargo-itself Area: Cargo's documentation label Jun 16, 2026
@clubby789

clubby789 commented Jun 16, 2026

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It might be good to wait on possible renaming (rust-lang/rust#157574 (comment)) before I push this forward

@clubby789 clubby789 marked this pull request as draft June 16, 2026 17:40
@rustbot rustbot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 16, 2026
@weihanglo

weihanglo commented Jun 17, 2026

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Would love to see some tests when you get back on this :)

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@rustbot rustbot added the S-waiting-on-author Status: The marked PR is awaiting some action (such as code changes) from the PR author. label Jun 18, 2026
@clubby789 clubby789 force-pushed the lint-rust-version branch 3 times, most recently from cc59ffa to 24c8147 Compare June 22, 2026 18:49
@clubby789 clubby789 changed the title feat: Add -Zlint-rust-version flag feat: Add -Zhint-msrv flag Jun 22, 2026
@clubby789 clubby789 marked this pull request as ready for review June 22, 2026 18:50
@rustbot rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 22, 2026
@clubby789

clubby789 commented Jun 22, 2026

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I couldn't figure out how to test what args are passed, and right now no lints make use of this flag

@weihanglo

weihanglo commented Jun 22, 2026

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I couldn't figure out how to test what args are passed, and right now no lints make use of this flag

Passing --verbose. For example, this

@clubby789 clubby789 force-pushed the lint-rust-version branch from 24c8147 to a5d4476 Compare June 22, 2026 20:18
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