Auto merge of #44735 - tirr-c:issue-42143, r=arielb1
Friendlier error message for closure argument type mismatch
Rebased #42270.
Fixes #42143.
---
`test.rs`:
```rust
fn main() {
foo(|_: i32, _: usize| ());
}
fn foo<F>(_: F) where F: Fn(&str, usize) {}
```
Before:
```
error[E0281]: type mismatch: `[closure@test.rs:2:9: 2:30]` implements the trait `std::ops::Fn<(i32, usize)>`, but the trait `for<'r> std::ops::Fn<(&'r str, usize)>` is required
--> test.rs:2:5
|
2 | foo(|_: i32, _: usize| ());
| ^^^ --------------------- implements `std::ops::Fn<(i32, usize)>`
| |
| expected &str, found i32
| requires `for<'r> std::ops::Fn<(&'r str, usize)>`
|
= note: required by `foo`
```
After (early):
```
error[E0631]: type mismatch in closure arguments
--> test.rs:2:5
|
2 | foo(|_: i32, _: usize| ());
| ^^^ --------------------- takes arguments of type `i32` and `usize`
| |
| expected arguments of type `&str` and `usize`
|
= note: required by `foo`
```
After (current):
```
error[E0631]: type mismatch in closure arguments
--> test.rs:2:5
|
2 | foo(|_: i32, _: usize| ());
| ^^^ --------------------- found signature of `fn(i32, usize) -> _`
| |
| expected signature of `for<'r> fn(&'r str, usize) -> _`
|
= note: required by `foo`
```
~~Compiler output has been changed, and a few tests are failing. Help me writing/fixing tests!~~
r? @nikomatsakis
4b8bf391fd