Sub-optional error message with slice rest syntax in patterns #72373
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A-diagnostics
Area: Messages for errors, warnings, and lints
A-parser
Area: The parsing of Rust source code to an AST.
A-patterns
Relating to patterns and pattern matching
A-slice-patterns
Area: slice patterns, https://github.com/rust-lang/rust/issues/23121
C-enhancement
Category: An issue proposing an enhancement or a PR with one.
D-papercut
Diagnostics: An error or lint that needs small tweaks.
T-compiler
Relevant to the compiler team, which will review and decide on the PR/issue.
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jonas-schievink
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A-diagnostics
estebank
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A-parser
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@rustbot claim |
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This gets us to: |
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Format and help message revised to: |
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Merged. Thanks for the report! |
JohnTitor
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May 30, 2020
Fix diagnostics for `@ ..` binding pattern in tuples and tuple structs Fixes rust-lang#72574 Associated rust-lang#72534 rust-lang#72373 Includes a new suggestion with `Applicability::MaybeIncorrect` confidence level. ### Before #### tuple ``` error: `..` patterns are not allowed here --> src/main.rs:4:19 | 4 | (_a, _x @ ..) => {} | ^^ | = note: only allowed in tuple, tuple struct, and slice patterns error[E0308]: mismatched types --> src/main.rs:4:9 | 3 | match x { | - this expression has type `({integer}, {integer}, {integer})` 4 | (_a, _x @ ..) => {} | ^^^^^^^^^^^^^ expected a tuple with 3 elements, found one with 2 elements | = note: expected tuple `({integer}, {integer}, {integer})` found tuple `(_, _)` error: aborting due to 2 previous errors ``` #### tuple struct ``` error: `..` patterns are not allowed here --> src/main.rs:6:25 | 6 | Binder(_a, _x @ ..) => {} | ^^ | = note: only allowed in tuple, tuple struct, and slice patterns error[E0023]: this pattern has 2 fields, but the corresponding tuple struct has 3 fields --> src/main.rs:6:9 | 1 | struct Binder(i32, i32, i32); | ----------------------------- tuple struct defined here ... 6 | Binder(_a, _x @ ..) => {} | ^^^^^^^^^^^^^^^^^^^ expected 3 fields, found 2 error: aborting due to 2 previous errors ``` ### After *Note: final output edited during source review discussion, see thread for details* #### tuple ``` error: `_x @` is not allowed in a tuple --> src/main.rs:4:14 | 4 | (_a, _x @ ..) => {} | ^^^^^^^ is only allowed in a slice | help: replace with `..` or use a different valid pattern | 4 | (_a, ..) => {} | ^^ error[E0308]: mismatched types --> src/main.rs:4:9 | 3 | match x { | - this expression has type `({integer}, {integer}, {integer})` 4 | (_a, _x @ ..) => {} | ^^^^^^^^^^^^^ expected a tuple with 3 elements, found one with 1 element | = note: expected tuple `({integer}, {integer}, {integer})` found tuple `(_,)` error: aborting due to 2 previous errors ``` #### tuple struct ``` error: `_x @` is not allowed in a tuple struct --> src/main.rs:6:20 | 6 | Binder(_a, _x @ ..) => {} | ^^^^^^^ is only allowed in a slice | help: replace with `..` or use a different valid pattern | 6 | Binder(_a, ..) => {} | ^^ error[E0023]: this pattern has 1 field, but the corresponding tuple struct has 3 fields --> src/main.rs:6:9 | 1 | struct Binder(i32, i32, i32); | ----------------------------- tuple struct defined here ... 6 | Binder(_a, _x @ ..) => {} | ^^^^^^^^^^^^^^^^^^^ expected 3 fields, found 1 error: aborting due to 2 previous errors ``` r? @estebank
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Gives:
I think a better error message should suggest the usage of
ref ts @...The text was updated successfully, but these errors were encountered: