Auto merge of #41559 - GuillaumeGomez:partial-eq-msg, r=estebank

Add better error message when == operator is badly used

Part of #40660.

With the following code:

```rust
fn foo<T: PartialEq>(a: &T, b: T) {
    a == b;
}

fn main() {
    foo(&1, 1);
}
```

It prints:

```
error[E0277]: the trait bound `&T: std::cmp::PartialEq<T>` is not satisfied
 --> test.rs:2:5
  |
2 |     a == b;
  |     ^^^^^^ can't compare `&T` with `T`
  |
  = help: the trait `std::cmp::PartialEq<T>` is not implemented for `&T`
  = help: consider adding a `where &T: std::cmp::PartialEq<T>` bound

error: aborting due to previous error
```

0 files changed, 0 insertions, 0 deletions