Fix suggestions for &a: T parameters
#97964
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Previously we were suggesting stuff like `fn f( &u32) {}`
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I left some general comments, but thanks @WaffleLapkin for such thorough UI tests.
| inner: &Pat<'_>, | ||
| expected: Ty<'tcx>, | ||
| ) { | ||
| fn borrow_pat_suggestion(&self, err: &mut Diagnostic, pat: &Pat<'_>, inner: &Pat<'_>) { |
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What is pat and inner in this case? Is pat the (direct?) parent of inner always?
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Yes. pat is Ref(inner), see
rust/compiler/rustc_typeck/src/check/pat.rs
Lines 201 to 202 in e9d49b2
rust/compiler/rustc_typeck/src/check/pat.rs
Line 1871 in e9d49b2
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Huh, could we simplify the redundant parameters then, if you think that would be simpler? Or if not, could you leave a comment that explains this relationship.
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What we really want is to have pat: Pat<PatKind::Ref> or something, but we don't have variant types so everything is messy :(
In the end I've removed inner (we need to match anyway, so that should be fine) and added comments about preconditions
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Thanks @WaffleLapkin, this is definitely an great improvement on the diagnostic. @bors r+ rollup |
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📌 Commit 33ccd76 has been approved by |
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…ions, r=compiler-errors
Fix suggestions for `&a: T` parameters
I've accidentally discovered that we have broken suggestions for `&a: T` parameters:
```rust
fn f(&mut bar: u32) {}
fn main() {
let _ = |&mut a| ();
}
```
```text
error[E0308]: mismatched types
--> ./t.rs:1:6
|
1 | fn f(&mut bar: u32) {}
| ^^^^^^^^-----
| | |
| | expected due to this
| expected `u32`, found `&mut _`
| help: did you mean `bar`: `&u32`
|
= note: expected type `u32`
found mutable reference `&mut _`
error[E0308]: mismatched types
--> ./t.rs:4:23
|
4 | let _: fn(u32) = |&mut a| ();
| ^^^^^--
| | |
| | expected due to this
| expected `u32`, found `&mut _`
| help: did you mean `a`: `&u32`
|
= note: expected type `u32`
found mutable reference `&mut _`
```
It's hard to see, but
1. The help span is overlapping with "expected" spans
2. It suggests `fn f( &u32) {}` (no `mut` and lost parameter name) and `|&u32 ()` (no closing `|` and lost parameter name)
I've tried to fix this.
r? `@compiler-errors`
Rollup of 7 pull requests Successful merges: - rust-lang#97202 (os str capacity documentation) - rust-lang#97964 (Fix suggestions for `&a: T` parameters) - rust-lang#98053 (Fix generic impl rustdoc json output) - rust-lang#98059 (Inline `const_eval_select`) - rust-lang#98092 (Fix sidebar items expand collapse) - rust-lang#98119 (Refactor path segment parameter error) - rust-lang#98135 (Add regression test for rust-lang#93775) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
I've accidentally discovered that we have broken suggestions for
&a: Tparameters:It's hard to see, but
fn f( &u32) {}(nomutand lost parameter name) and|&u32 ()(no closing|and lost parameter name)I've tried to fix this.
r? @compiler-errors