feat: Add lint for global use of `hint-mostly-unused` #15995

Muscraft · 2025-09-21T21:34:49Z

This PR adds a lint that checks for global use of hint-mostly-unused. This also adds a "workspace lint pass", since we only want to lint on the workspace's [profile], as all other [profile] are ignored. This new pass uses [workspace.lints.cargo] for configuration if [workspace] exists, and [lints] if it doesn't¹.

Note: This lint will get emitted if -Zprofile-hint-mostly-unused is set, regardless of whether -Zcargo-lints is set.

CC @joshtriplett

We can change the behavior in the future if it is not correct ↩

rustbot · 2025-09-21T21:34:54Z

r? @weihanglo

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joshtriplett · 2025-09-22T01:13:59Z

src/cargo/util/lints.rs

+        if lint_level.is_error() {
+            *error_count += 1;
+        }
+        let title = "use of `hint-mostly-unused` in a global context";


Suggested change

let title = "use of `hint-mostly-unused` in a global context";

let title = "`hint-mostly-unused` should not be applied globally";

FYI I just noticed that my suggestion was the inverse of your
#15995 (comment)

joshtriplett · 2025-09-22T01:16:35Z

Looks great, thank you! I posted one minor wording tweak (which needs corresponding updates to the test output), but otherwise, r=me.

Muscraft · 2025-09-22T03:01:49Z

Looks great, thank you! I posted one minor wording tweak (which needs corresponding updates to the test output), but otherwise, r=me.

I can't r=me on your behalf, as the merge queue requires the PR to be approved by some other than the author

tests/testsuite/lints/global_hint_mostly_unused.rs

src/cargo/core/workspace.rs

src/cargo/util/lints.rs

tests/testsuite/lints/blanket_hint_mostly_unused.rs

src/cargo/core/workspace.rs

tests/testsuite/lints/blanket_hint_mostly_unused.rs

epage · 2025-09-23T00:58:11Z

This looks great! Thank you for your patience through the many back-and-forths!

Update cargo submodule 17 commits in 966f94733bbc94ca51ff9f1e4c49ad250ebbdc50..f2932725b045d361ff5f18ba02b1409dd1f44e71 2025-09-16 17:24:45 +0000 to 2025-09-24 11:31:26 +0000 - fix: use `host-tuple` for host target subsitution (rust-lang/cargo#16003) - test(build-std): move away from panic_immediate_abort (rust-lang/cargo#16006) - fix: Sparse URLs in `TomlLockfileSourceId` (rust-lang/cargo#15990) - refactor(gctx): extract toml dotted keys validation (rust-lang/cargo#15998) - feat: Add lint for global use of `hint-mostly-unused` (rust-lang/cargo#15995) - Make GlobalContext Sync (rust-lang/cargo#15967) - chore(deps): update cargo-semver-checks to v0.44.0 (rust-lang/cargo#15993) - fix(frontatter): Only allow horizontal whitespace after fences (rust-lang/cargo#15975) - docs: Add Lockfile schemas docs (rust-lang/cargo#15989) - Add parallel frontend to the build performance guide (rust-lang/cargo#15970) - chore(deps): update msrv (3 versions) to v1.88 (rust-lang/cargo#15988) - chore(deps): update msrv (1 version) to 45C0 v1.90 (rust-lang/cargo#15984) - feat(cargo-util-schemas): Move lockfile schemas (rust-lang/cargo#15980) - Clarify multiple version requirement behavior (rust-lang/cargo#15979) - Adds ghostty as supported terminal for term integration (OSC 9;4) (rust-lang/cargo#15977) - docs(team): Fixed broken office hours link (rust-lang/cargo#15976) - docs: Clarify git sources vs git registries in source replacement documentation (rust-lang/cargo#15974) r? ghost

Update cargo submodule 17 commits in 966f94733bbc94ca51ff9f1e4c49ad250ebbdc50..f2932725b045d361ff5f18ba02b1409dd1f44e71 2025-09-16 17:24:45 +0000 to 2025-09-24 11:31:26 +0000 - fix: use `host-tuple` for host target subsitution (rust-lang/cargo#16003) - test(build-std): move away from panic_immediate_abort (rust-lang/cargo#16006) - fix: Sparse URLs in `TomlLockfileSourceId` (rust-lang/cargo#15990) - refactor(gctx): extract toml dotted keys validation (rust-lang/cargo#15998) - feat: Add lint for global use of `hint-mostly-unused` (rust-lang/cargo#15995) - Make GlobalContext Sync (rust-lang/cargo#15967) - chore(deps): update cargo-semver-checks to v0.44.0 (rust-lang/cargo#15993) - fix(frontatter): Only allow horizontal whitespace after fences (rust-lang/cargo#15975) - docs: Add Lockfile schemas docs (rust-lang/cargo#15989) - Add parallel frontend to the build performance guide (rust-lang/cargo#15970) - chore(deps): update msrv (3 versions) to v1.88 (rust-lang/cargo#15988) - chore(deps): update msrv (1 version) to v1.90 (rust-lang/cargo#15984) - feat(cargo-util-schemas): Move lockfile schemas (rust-lang/cargo#15980) - Clarify multiple version requirement behavior (rust-lang/cargo#15979) - Adds ghostty as supported terminal for term integration (OSC 9;4) (rust-lang/cargo#15977) - docs(team): Fixed broken office hours link (rust-lang/cargo#15976) - docs: Clarify git sources vs git registries in source replacement documentation (rust-lang/cargo#15974) r? ghost

rustbot assigned weihanglo Sep 21, 2025

rustbot added A-documenting-cargo-itself Area: Cargo's documentation A-workspaces Area: workspaces S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 21, 2025

joshtriplett reviewed Sep 22, 2025

View reviewed changes

Muscraft force-pushed the global-mostly-unused-lint branch from 6110bb8 to 3a1de15 Compare September 22, 2025 01:59