Emit diagnostic when calling methods on the unit type in method chains
Fixes#104204.
What this PR does: If a method is not found somewhere in a call chain, we check if we called earlier a method with signature `(&mut T, ...) -> ()`. If this is the case then we emit a diagnostic message.
For example given input:
```
vec![1, 2, 3].into_iter().collect::<Vec<i32>>().sort_by_key(|i| i).sort();
```
the current output is:
```
error[E0599]: no method named `sort` found for unit type `()` in the current scope
--> hello.rs:3:72
|
3 | vec![1, 2, 3].into_iter().collect::<Vec<i32>>().sort_by_key(|i| i).sort();
| ^^^^ method not found in `()`
```
after this PR it will be:
```
error[E0599]: no method named `sort` found for unit type `()` in the current scope
--> ./hello.rs:3:72
|
3 | vec![1, 2, 3].into_iter().collect::<Vec<i32>>().sort_by_key(|i| i).sort();
| ^^^^ method not found in `()`
|
note: method `sort_by_key` modifies its receiver in-place, it is not meant to be used in method chains.
--> ./hello.rs:3:53
|
3 | vec![1, 2, 3].into_iter().collect::<Vec<i32>>().sort_by_key(|i| i).sort();
| ^^^^^^^^^^^ this call modifies its receiver in-place
```
b17ee106d8