4
Suggest a trailing comma if a 1-tuple is expected and a parenthesized expression...
source link: https://github.com/rust-lang/rust/pull/86116
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This pull request fixes #86100. The following code:
fn main() {
let t: (i32,) = (1);
}currently produces:
warning: unnecessary parentheses around assigned value
--> test.rs:2:21
|
2 | let t: (i32,) = (1);
| ^^^ help: remove these parentheses
|
= note: `#[warn(unused_parens)]` on by default
error[E0308]: mismatched types
--> test.rs:2:21
|
2 | let t: (i32,) = (1);
| ------ ^^^ expected tuple, found integer
| |
| expected due to this
|
= note: expected tuple `(i32,)`
found type `{integer}`
error: aborting due to previous error; 1 warning emitted
With my changes, I get the same warning and the following error:
error[E0308]: mismatched types
--> test.rs:2:21
|
2 | let t: (i32,) = (1);
| ------ ^^^ expected tuple, found integer
| |
| expected due to this
|
= note: expected tuple `(i32,)`
found type `{integer}`
help: use a trailing comma to create a tuple with one element
|
2 | let t: (i32,) = (1,);
| ^^^^
i.e. I have added a suggestion to add a trailing comma to create a 1-tuple. This suggestion is only issued if a 1-tuple is expected and the expression ((1) in the example above) is surrounded by parentheses and does not already have a tuple type. In this situation, I'd say that it is pretty likely that the user meant to create a tuple.
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