Improve irrefutable let-else lint wording by ozankenangungor · Pull Request #153048 · rust-lang/rust

ozankenangungor · 2026-02-24T14:37:14Z

Update the irrefutable_let_patterns wording for let-else to better reflect that the else clause is unreachable when the LHS pattern always matches.

Closes #152938

rustbot · 2026-02-24T14:37:20Z

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tests/ui/let-else/let-else-irrefutable.stderr

tests/ui/let-else/let-else-irrefutable-152938.stderr

rustbot · 2026-02-24T18:39:53Z

Some changes occurred in match checking

cc @Nadrieril

estebank · 2026-02-24T19:10:30Z

compiler/rustc_mir_build/src/errors.rs

    *[other] these patterns
-} will always match, so the `else` clause is useless"
+} will always succeed, so the `else` clause is unreachable"
 )]


Can we turn this into a span_label pointing at the pattern (in most cases, a binding)? It might even make sense to detect when it is an identifier binding to explain in a note that all let bindings are patterns.

Thanks, good idea. Right now the primary span already points at the pattern, and I tried to keep the wording generic to avoid extra logic. I would prefer to keep this pr small, I can follow up separately if we want to explore a span label binding specific note.

compiler/rustc_mir_build/src/errors.rs

Kivooeo · 2026-02-25T21:56:56Z

I don't think that creating a new field just for this is reasonable, I think it would make more much sense to pass else_span as argument

ozankenangungor · 2026-02-26T08:49:32Z

I don't think that creating a new field just for this is reasonable, I think it would make more much sense to pass else_span as argument

Thanks, that makes sense. I will switch this to pass else_span through as an argument instead of storing it on MatchVisitor.

tests/ui/let-else/let-else-irrefutable-152938.stderr

rustbot · 2026-02-28T18:30:28Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

ozankenangungor · 2026-03-01T02:02:11Z

@rustbot ready

rustbot · 2026-03-03T00:40:10Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

Kivooeo

nice! thanks for the effort you put into addressing all the feedback and going through multiple rounds of review

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Kivooeo · 2026-03-03T21:34:37Z

@bors r+ rollup

rust-bors · 2026-03-03T21:34:39Z

📌 Commit a8d4eee has been approved by Kivooeo

It is now in the queue for this repository.

Rollup of 8 pull requests Successful merges: - #153280 (Add regression test for `doc(fake_variadic)` on reexports) - #153302 (x86: reserve `bl` and `bh` registers to match `rbx`) - #153358 (Boundary tests for various Duration-float operations) - #153048 (Improve irrefutable let-else lint wording) - #153258 (diag: Suppress `.clone()` suggestion inside derive macro expansions) - #153272 (Add `Path::absolute` method as alias for `std::path::absolute`) - #153295 (update panicking() docs for panic=abort) - #153352 (Migration of `LintDiagnostic` - part 6)

Rollup merge of #153048 - ozankenangungor:fix-irrefutable-let-else-wording, r=Kivooeo Improve irrefutable let-else lint wording Update the `irrefutable_let_patterns` wording for let-else to better reflect that the `else` clause is unreachable when the LHS pattern always matches. Closes #152938

rustbot assigned davidtwco Feb 24, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Feb 24, 2026

Kivooeo reviewed Feb 24, 2026

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Kivooeo assigned Kivooeo and unassigned davidtwco Feb 24, 2026

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ozankenangungor force-pushed the fix-irrefutable-let-else-wording branch from 1af1bc9 to 8f4b39f Compare February 24, 2026 18:39

ozankenangungor force-pushed the fix-irrefutable-let-else-wording branch from 8f4b39f to 92c4925 Compare February 24, 2026 19:00

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ozankenangungor requested a review from fmease February 25, 2026 16:27

ozankenangungor force-pushed the fix-irrefutable-let-else-wording branch from 92c4925 to eba9297 Compare February 26, 2026 08:29

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ozankenangungor force-pushed the fix-irrefutable-let-else-wording branch from eba9297 to db88aa2 Compare February 26, 2026 10:46

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ozankenangungor requested a review from Kivooeo March 1, 2026 02:01

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Mar 1, 2026

Improve irrefutable let-else lint wording

a8d4eee

ozankenangungor force-pushed the fix-irrefutable-let-else-wording branch from 906e74b to a8d4eee Compare March 3, 2026 00:40

Kivooeo approved these changes Mar 3, 2026

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Zalathar mentioned this pull request Mar 4, 2026

Rollup of 8 pull requests #153377

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rust-bors bot merged commit 70287b9 into rust-lang:main Mar 4, 2026
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rustbot added this to the 1.96.0 milestone Mar 4, 2026

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