Use `let...else` instead of `match foo { ... _ => return };` and `if let ... else return` #148837

estebank · 2025-11-11T20:12:42Z

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rustbot · 2025-11-11T20:12:46Z

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

Some changes occurred in compiler/rustc_codegen_ssa

cc @WaffleLapkin

HIR ty lowering was modified

cc @fmease

Some changes occurred in compiler/rustc_codegen_gcc

cc @antoyo, @GuillaumeGomez

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

rustbot · 2025-11-11T20:12:48Z

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bjorn3 · 2025-11-11T21:21:30Z

compiler/rustc_codegen_gcc/src/intrinsic/simd.rs

Maybe skip this for now to avoid conflicts with #148481?

chenyukang · 2025-11-12T06:30:18Z

do we have a style check for this?

estebank · 2025-11-12T18:35:42Z

@chenyukang there's a pedantic clippy lint that we could enable: https://rust-lang.github.io/rust-clippy/master/index.html#/let-else

Kivooeo

Thanks for taking time on this, looks good on compiler side, would this reasonable to split compiler and library parts? I'm not sure if I privileged enough to review the library part

There is some places that looks better with the if let guard feature to remove nesting

View changes since this review

compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs

rustbot · 2025-12-09T00:58:50Z

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

Kivooeo · 2025-12-09T18:39:44Z

compiler/rustc_ast/src/lib.rs


 // tidy-alphabetical-start
 #![cfg_attr(bootstrap, feature(array_windows))]
+#![deny(clippy::manual_let_else)]


let's not add this lint anywhere yet, I think CI will never stop complain about it :D

I'm finding them instructive :)

ah, so feel free to «r=me» once CI passed

…bilee Use `let`...`else` instead of `match foo { ... _ => return };` and `if let ... else return` in std Split off rust-lang#148837.

Rollup merge of #149795 - estebank:let-else-std, r=workingjubilee Use `let`...`else` instead of `match foo { ... _ => return };` and `if let ... else return` in std Split off #148837.

Use `let`...`else` instead of `match foo { ... _ => return };` and `if let ... else return` in std Split off rust-lang/rust#148837.

compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs

bors · 2025-12-12T01:36:33Z

☔ The latest upstream changes (presumably #149645) made this pull request unmergeable. Please resolve the merge conflicts.

…let ... else return`

rustbot · 2025-12-12T17:55:45Z

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.

estebank · 2025-12-12T19:09:32Z

@bors r=Kivooeo

bors · 2025-12-12T19:09:35Z

📌 Commit 97c7742 has been approved by Kivooeo

It is now in the queue for this repository.

Use `let...else` instead of `match foo { ... _ => return };` and `if let ... else return`

rustbot assigned wesleywiser Nov 11, 2025

estebank force-pushed the let-else branch from 008fdbd to 7afd776 Compare November 11, 2025 20:17

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estebank mentioned this pull request Dec 9, 2025

Use let...else instead of match foo { ... _ => return }; and if let ... else return in std #149795

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estebank force-pushed the let-else branch from 7afd776 to 5d9d399 Compare December 9, 2025 00:11

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estebank force-pushed the let-else branch 2 times, most recently from f61284d to 9c1998b Compare December 9, 2025 00:43

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estebank force-pushed the let-else branch from cbfd1b3 to 02b6715 Compare December 9, 2025 17:30

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estebank force-pushed the let-else branch from 02b6715 to 446e275 Compare December 9, 2025 23:26

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estebank force-pushed the let-else branch from 446e275 to d2f050d Compare December 10, 2025 00:59

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rust-timer added a commit that referenced this pull request Dec 10, 2025

Unrolled build for #149795

c2d36f8

Rollup merge of #149795 - estebank:let-else-std, r=workingjubilee Use `let`...`else` instead of `match foo { ... _ => return };` and `if let ... else return` in std Split off #148837.

estebank force-pushed the let-else branch from d2f050d to 5f4a6cd Compare December 11, 2025 16:37

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estebank force-pushed the let-else branch from d794edb to a9d898c Compare December 11, 2025 21:39

estebank added 3 commits December 12, 2025 17:52

Use let...else instead of match foo { ... _ => return }; and `if …

146711f

…let ... else return`

#![deny(clippy::manual_let_else)] in some rustc modules

a49c175

revert one change from rustc_next_trait_solver

97c7742

estebank force-pushed the let-else branch from a9d898c to 97c7742 Compare December 12, 2025 17:55

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 12, 2025

jhpratt added a commit to jhpratt/rust that referenced this pull request Dec 13, 2025

Rollup merge of rust-lang#148837 - estebank:let-else, r=Kivooeo

4ed48d8

Use `let...else` instead of `match foo { ... _ => return };` and `if let ... else return`

jhpratt mentioned this pull request Dec 13, 2025

Rollup of 11 pull requests #149940

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Use let...else instead of match foo { ... _ => return }; and if let ... else return #148837

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Use let...else instead of match foo { ... _ => return }; and if let ... else return #148837

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Use `let...else` instead of `match foo { ... _ => return };` and `if let ... else return` #148837

Use `let...else` instead of `match foo { ... _ => return };` and `if let ... else return` #148837

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