On unused binding or binding not present in all patterns, suggest potential typo of unit struct/variant or const #145827

estebank · 2025-08-24T19:23:02Z

When encountering an or-pattern with a binding not available in all patterns, look for consts and unit struct/variants that have similar names as the binding to detect typos.

error[E0408]: variable `Ban` is not bound in all patterns
  --> $DIR/binding-typo.rs:22:9
   |
LL |         (Foo, _) | (Ban, Foo) => {}
   |         ^^^^^^^^    --- variable not in all patterns
   |         |
   |         pattern doesn't bind `Ban`
   |
help: you might have meant to use the similarly named unit variant `Bar`
   |
LL -         (Foo, _) | (Ban, Foo) => {}
LL +         (Foo, _) | (Bar, Foo) => {}
   |

For items that are not in the immedate scope, suggest the full path for them:

error[E0408]: variable `Non` is not bound in all patterns
  --> $DIR/binding-typo-2.rs:51:16
   |
LL |         (Non | Some(_))=> {}
   |          ---   ^^^^^^^ pattern doesn't bind `Non`
   |          |
   |          variable not in all patterns
   |
help: you might have meant to use the similarly named unit variant `None`
   |
LL -         (Non | Some(_))=> {}
LL +         (core::option::Option::None | Some(_))=> {}
   |

When encountering a typo in a pattern that gets interpreted as an unused binding, look for unit struct/variant of the same type as the binding:

error: unused variable: `Non`
  --> $DIR/binding-typo-2.rs:36:9
   |
LL |         Non => {}
   |         ^^^
   |
help: if this is intentional, prefix it with an underscore
   |
LL |         _Non => {}
   |         +
help: you might have meant to pattern match on the similarly named variant `None`
   |
LL -         Non => {}
LL +         std::prelude::v1::None => {}
   |

Suggest constant on unused binding in a pattern

error: unused variable: `Batery`
  --> $DIR/binding-typo-2.rs:110:9
   |
LL |         Batery => {}
   |         ^^^^^^
   |
help: if this is intentional, prefix it with an underscore
   |
LL |         _Batery => {}
   |         +
help: you might have meant to pattern match on the similarly named constant `Battery`
   |
LL |         Battery => {}
   |            +

Fix #51976.

rustbot · 2025-08-24T19:23:06Z

r? @fee1-dead

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``` error[E0408]: variable `Ban` is not bound in all patterns --> f12.rs:9:9 | 9 | (Foo,Bar)|(Ban,Foo) => {} | ^^^^^^^^^ --- variable not in all patterns | | | pattern doesn't bind `Ban` | help: you might have meant to use the similarly named previously used binding `Bar` | 9 - (Foo,Bar)|(Ban,Foo) => {} 9 + (Foo,Bar)|(Bar,Foo) => {} | ```

fee1-dead · 2025-08-27T13:32:45Z

Hmmm. I'm not entirely sure whether this actually fixes the original issue as the original issue is about a variant in scope. I would like to see the original issue in a test.

…ts/variants for suggestions When encountering an or-pattern with a binding not available in all patterns, look for consts and unit struct/variants that have similar names as the binding to detect typos. ``` error[E0408]: variable `Ban` is not bound in all patterns --> $DIR/binding-typo.rs:22:9 | LL | (Foo, _) | (Ban, Foo) => {} | ^^^^^^^^ --- variable not in all patterns | | | pattern doesn't bind `Ban` | help: you might have meant to use the similarly named unit variant `Bar` | LL - (Foo, _) | (Ban, Foo) => {} LL + (Foo, _) | (Bar, Foo) => {} | ``` For items that are not in the immedate scope, suggest the full path for them: ``` error[E0408]: variable `Non` is not bound in all patterns --> $DIR/binding-typo-2.rs:51:16 | LL | (Non | Some(_))=> {} | --- ^^^^^^^ pattern doesn't bind `Non` | | | variable not in all patterns | help: you might have meant to use the similarly named unit variant `None` | LL - (Non | Some(_))=> {} LL + (core::option::Option::None | Some(_))=> {} | ```

…r name When encountering a typo in a pattern that gets interpreted as an unused binding, look for unit struct/variant of the same type as the binding: ``` error: unused variable: `Non` --> $DIR/binding-typo-2.rs:36:9 | LL | Non => {} | ^^^ | help: if this is intentional, prefix it with an underscore | LL | _Non => {} | + help: you might have meant to pattern match on the similarly named variant `None` | LL - Non => {} LL + std::prelude::v1::None => {} | ```

``` error: unused variable: `Batery` --> $DIR/binding-typo-2.rs:110:9 | LL | Batery => {} | ^^^^^^ | help: if this is intentional, prefix it with an underscore | LL | _Batery => {} | + help: you might have meant to pattern match on the similarly named constant `Battery` | LL | Battery => {} | + ```

tests/ui/resolve/resolve-inconsistent-names.stderr

estebank · 2025-08-30T18:00:45Z

tests/ui/fn/mut-arg-of-borrowed-type-meant-to-be-arg-of-mut-borrow.rs

@@ -1,5 +1,5 @@
 //@ run-rustfix
-#![deny(unused_assignments, unused_variables)]
+#![deny(unused_assignments)]


Changed because that lint now emits:

error: variable `object` is assigned to, but never used --> $DIR/mut-arg-of-borrowed-type-meant-to-be-arg-of-mut-borrow.rs:11:23 | LL | fn change_object2(mut object: &Object) { | ^^^^^^ | = note: consider using `_object` instead note: the lint level is defined here --> $DIR/mut-arg-of-borrowed-type-meant-to-be-arg-of-mut-borrow.rs:2:29 | LL | #![deny(unused_assignments, unused_variables)] | ^^^^^^^^^^^^^^^^ help: you might have meant to pattern match on the similarly named struct `Object` (notice the capitalization) | LL - fn change_object2(mut object: &Object) { LL + fn change_object2(mut Object: &Object) { |

which would make this test no longer run-rustfixable.

estebank · 2025-08-31T23:40:32Z

tests/ui/or-patterns/binding-typo.rs

+fn foo(x: (Lol, Lol)) {
+    use Lol::*;
+    match &x {
+        (Foo, Bar) | (Ban, Foo) => {}


This is the original case in the ticket, where it was a simple typo and the binding was available in the other or-pattern.

estebank · 2025-08-31T23:40:56Z

tests/ui/or-patterns/binding-typo.rs

+        _ => {}
+    }
+    match &x {
+        (Foo, _) | (Ban, Foo) => {}


This is the case where the typo'd variant is not even present in the other or-pattern.

estebank · 2025-08-31T23:41:28Z

tests/ui/or-patterns/binding-typo-2.rs

+    }
+    match Some(42) {
+        Some(_) => {}
+        Non => {}


Test when an or-pattern isn't involved.

fee1-dead · 2025-09-01T19:32:57Z

Sorry, I lack capacity at the moment and have to reroll.

r? compiler

jackh726 · 2025-09-03T16:44:03Z

@bors r+

bors · 2025-09-03T16:44:05Z

📌 Commit 86085b4 has been approved by jackh726

It is now in the queue for this repository.

On unused binding or binding not present in all patterns, suggest potential typo of unit struct/variant or const When encountering an or-pattern with a binding not available in all patterns, look for consts and unit struct/variants that have similar names as the binding to detect typos. ``` error[E0408]: variable `Ban` is not bound in all patterns --> $DIR/binding-typo.rs:22:9 | LL | (Foo, _) | (Ban, Foo) => {} | ^^^^^^^^ --- variable not in all patterns | | | pattern doesn't bind `Ban` | help: you might have meant to use the similarly named unit variant `Bar` | LL - (Foo, _) | (Ban, Foo) => {} LL + (Foo, _) | (Bar, Foo) => {} | ``` For items that are not in the immedate scope, suggest the full path for them: ``` error[E0408]: variable `Non` is not bound in all patterns --> $DIR/binding-typo-2.rs:51:16 | LL | (Non | Some(_))=> {} | --- ^^^^^^^ pattern doesn't bind `Non` | | | variable not in all patterns | help: you might have meant to use the similarly named unit variant `None` | LL - (Non | Some(_))=> {} LL + (core::option::Option::None | Some(_))=> {} | ``` When encountering a typo in a pattern that gets interpreted as an unused binding, look for unit struct/variant of the same type as the binding: ``` error: unused variable: `Non` --> $DIR/binding-typo-2.rs:36:9 | LL | Non => {} | ^^^ | help: if this is intentional, prefix it with an underscore | LL | _Non => {} | + help: you might have meant to pattern match on the similarly named variant `None` | LL - Non => {} LL + std::prelude::v1::None => {} | ``` Suggest constant on unused binding in a pattern ``` error: unused variable: `Batery` --> $DIR/binding-typo-2.rs:110:9 | LL | Batery => {} | ^^^^^^ | help: if this is intentional, prefix it with an underscore | LL | _Batery => {} | + help: you might have meant to pattern match on the similarly named constant `Battery` | LL | Battery => {} | + ``` Fix rust-lang#51976.

Rollup of 24 pull requests Successful merges: - #140459 (Add `read_buf` equivalents for positioned reads) - #143725 (core: add Peekable::next_if_map) - #145209 (Stabilize `path_add_extension`) - #145342 (fix drop scope for `super let` bindings within `if let`) - #145750 (raw_vec.rs: Remove superfluous fn alloc_guard) - #145827 (On unused binding or binding not present in all patterns, suggest potential typo of unit struct/variant or const) - #145932 (Allow `inline(always)` with a target feature behind a unstable feature `target_feature_inline_always`.) - #145962 (Ensure we emit an allocator shim when only some crate types need one) - #145963 (Add LSX accelerated implementation for source file analysis) - #146054 (add `#[must_use]` to `array::repeat`) - #146090 (Derive `PartialEq` for `InvisibleOrigin`) - #146112 (don't uppercase error messages) - #146120 (Correct typo in `rustc_errors` comment) - #146124 (Test `rustc-dev` in `distcheck`) - #146127 (Rename `ToolRustc` to `ToolRustcPrivate`) - #146131 (rustdoc-search: add test case for indexing every item type) - #146134 (llvm: nvptx: Layout update to match LLVM) - #146136 (docs(std): add missing closing code block fences in doc comments) - #146137 (Disallow frontmatter in `--cfg` and `--check-cfg` arguments) - #146140 (compiletest: cygwin follows windows in using PATH for dynamic libraries) - #146150 (fix(rustdoc): match rustc `--emit` precedence ) - #146155 (Make bootstrap self test parallel) - #146161 ([rustdoc] Uncomment code to add scraped rustdoc examples in loaded paths) - #146172 (triagebot: configure some pings when certain attributes are used) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #145827 - estebank:issue-51976, r=jackh726 On unused binding or binding not present in all patterns, suggest potential typo of unit struct/variant or const When encountering an or-pattern with a binding not available in all patterns, look for consts and unit struct/variants that have similar names as the binding to detect typos. ``` error[E0408]: variable `Ban` is not bound in all patterns --> $DIR/binding-typo.rs:22:9 | LL | (Foo, _) | (Ban, Foo) => {} | ^^^^^^^^ --- variable not in all patterns | | | pattern doesn't bind `Ban` | help: you might have meant to use the similarly named unit variant `Bar` | LL - (Foo, _) | (Ban, Foo) => {} LL + (Foo, _) | (Bar, Foo) => {} | ``` For items that are not in the immedate scope, suggest the full path for them: ``` error[E0408]: variable `Non` is not bound in all patterns --> $DIR/binding-typo-2.rs:51:16 | LL | (Non | Some(_))=> {} | --- ^^^^^^^ pattern doesn't bind `Non` | | | variable not in all patterns | help: you might have meant to use the similarly named unit variant `None` | LL - (Non | Some(_))=> {} LL + (core::option::Option::None | Some(_))=> {} | ``` When encountering a typo in a pattern that gets interpreted as an unused binding, look for unit struct/variant of the same type as the binding: ``` error: unused variable: `Non` --> $DIR/binding-typo-2.rs:36:9 | LL | Non => {} | ^^^ | help: if this is intentional, prefix it with an underscore | LL | _Non => {} | + help: you might have meant to pattern match on the similarly named variant `None` | LL - Non => {} LL + std::prelude::v1::None => {} | ``` Suggest constant on unused binding in a pattern ``` error: unused variable: `Batery` --> $DIR/binding-typo-2.rs:110:9 | LL | Batery => {} | ^^^^^^ | help: if this is intentional, prefix it with an underscore | LL | _Batery => {} | + help: you might have meant to pattern match on the similarly named constant `Battery` | LL | Battery => {} | + ``` Fix #51976.

Zalathar · 2025-09-04T09:51:34Z

Perf results from rollup (regressions and improvements):

Rollup of 24 pull requests Successful merges: - rust-lang/rust#140459 (Add `read_buf` equivalents for positioned reads) - rust-lang/rust#143725 (core: add Peekable::next_if_map) - rust-lang/rust#145209 (Stabilize `path_add_extension`) - rust-lang/rust#145342 (fix drop scope for `super let` bindings within `if let`) - rust-lang/rust#145750 (raw_vec.rs: Remove superfluous fn alloc_guard) - rust-lang/rust#145827 (On unused binding or binding not present in all patterns, suggest potential typo of unit struct/variant or const) - rust-lang/rust#145932 (Allow `inline(always)` with a target feature behind a unstable feature `target_feature_inline_always`.) - rust-lang/rust#145962 (Ensure we emit an allocator shim when only some crate types need one) - rust-lang/rust#145963 (Add LSX accelerated implementation for source file analysis) - rust-lang/rust#146054 (add `#[must_use]` to `array::repeat`) - rust-lang/rust#146090 (Derive `PartialEq` for `InvisibleOrigin`) - rust-lang/rust#146112 (don't uppercase error messages) - rust-lang/rust#146120 (Correct typo in `rustc_errors` comment) - rust-lang/rust#146124 (Test `rustc-dev` in `distcheck`) - rust-lang/rust#146127 (Rename `ToolRustc` to `ToolRustcPrivate`) - rust-lang/rust#146131 (rustdoc-search: add test case for indexing every item type) - rust-lang/rust#146134 (llvm: nvptx: Layout update to match LLVM) - rust-lang/rust#146136 (docs(std): add missing closing code block fences in doc comments) - rust-lang/rust#146137 (Disallow frontmatter in `--cfg` and `--check-cfg` arguments) - rust-lang/rust#146140 (compiletest: cygwin follows windows in using PATH for dynamic libraries) - rust-lang/rust#146150 (fix(rustdoc): match rustc `--emit` precedence ) - rust-lang/rust#146155 (Make bootstrap self test parallel) - rust-lang/rust#146161 ([rustdoc] Uncomment code to add scraped rustdoc examples in loaded paths) - rust-lang/rust#146172 (triagebot: configure some pings when certain attributes are used) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 24 pull requests Successful merges: - rust-lang#140459 (Add `read_buf` equivalents for positioned reads) - rust-lang#143725 (core: add Peekable::next_if_map) - rust-lang#145209 (Stabilize `path_add_extension`) - rust-lang#145342 (fix drop scope for `super let` bindings within `if let`) - rust-lang#145750 (raw_vec.rs: Remove superfluous fn alloc_guard) - rust-lang#145827 (On unused binding or binding not present in all patterns, suggest potential typo of unit struct/variant or const) - rust-lang#145932 (Allow `inline(always)` with a target feature behind a unstable feature `target_feature_inline_always`.) - rust-lang#145962 (Ensure we emit an allocator shim when only some crate types need one) - rust-lang#145963 (Add LSX accelerated implementation for source file analysis) - rust-lang#146054 (add `#[must_use]` to `array::repeat`) - rust-lang#146090 (Derive `PartialEq` for `InvisibleOrigin`) - rust-lang#146112 (don't uppercase error messages) - rust-lang#146120 (Correct typo in `rustc_errors` comment) - rust-lang#146124 (Test `rustc-dev` in `distcheck`) - rust-lang#146127 (Rename `ToolRustc` to `ToolRustcPrivate`) - rust-lang#146131 (rustdoc-search: add test case for indexing every item type) - rust-lang#146134 (llvm: nvptx: Layout update to match LLVM) - rust-lang#146136 (docs(std): add missing closing code block fences in doc comments) - rust-lang#146137 (Disallow frontmatter in `--cfg` and `--check-cfg` arguments) - rust-lang#146140 (compiletest: cygwin follows windows in using PATH for dynamic libraries) - rust-lang#146150 (fix(rustdoc): match rustc `--emit` precedence ) - rust-lang#146155 (Make bootstrap self test parallel) - rust-lang#146161 ([rustdoc] Uncomment code to add scraped rustdoc examples in loaded paths) - rust-lang#146172 (triagebot: configure some pings when certain attributes are used) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned fee1-dead Aug 24, 2025

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 Aug 24, 2025

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estebank force-pushed the issue-51976 branch from e0b35c3 to 8dbdb17 Compare August 25, 2025 15:16

estebank added 4 commits August 29, 2025 20:39

Add test for typo in or-pattern binding

bd0ea61

estebank commented Aug 30, 2025

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tests/ui/resolve/resolve-inconsistent-names.stderr Outdated Show resolved Hide resolved

Avoid unnecessary suggestion in or-pattern

86085b4

estebank changed the title ~~On binding not present in all patterns, suggest potential typo~~ On unused binding or binding not present in all patterns, suggest potential typo of unit struct/variant or const Aug 30, 2025

estebank commented Aug 30, 2025

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estebank commented Aug 31, 2025

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rustbot assigned jackh726 and unassigned fee1-dead Sep 1, 2025

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 Sep 3, 2025

Zalathar mentioned this pull request Sep 4, 2025

Rollup of 24 pull requests #146185

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bors merged commit 3a6ae11 into rust-lang:master Sep 4, 2025
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