Rollup merge of #64859 - Centril:const-def-here-new-var, r=estebank

check_match: improve diagnostics for `let A = 2;` with `const A: i32 = 3`

For example:

```
error[E0005]: refutable pattern in local binding: `std::i32::MIN..=1i32` and `3i32..=std::i32::MAX` not covered
  --> $DIR/const-pat-non-exaustive-let-new-var.rs:2:9
   |
LL |     let A = 3;
   |         ^
   |         |
   |         interpreted as a constant pattern, not a new variable
   |         help: introduce a variable instead: `a_var`
...
LL |     const A: i32 = 2;
   |     ----------------- constant defined here
```

r? @estebank
cc @matthiaskrgr @rpjohnst

0 files changed, 0 insertions, 0 deletions