Auto merge of #11387 - y21:issue11371, r=blyxyas

[`unnecessary_unwrap`]: lint on `.as_ref().unwrap()`

Closes #11371

This turned out to be a little more code than I originally thought, because the lint also makes sure to not lint if the user tries to mutate the option:
```rs
if option.is_some() {
  option = None;
  option.unwrap(); // don't lint here
}
```
... which means that even if we taught this lint to recognize `.as_mut()`, it would *still* not lint because that would count as a mutation. So we need to allow `.as_mut()` calls but reject other kinds of mutations.
Unfortunately it doesn't look like this is possible with `is_potentially_mutated` (seeing what kind of mutation happened).
This replaces it with a custom little visitor that does basically what it did before, but also allows `.as_mut()`.

changelog: [`unnecessary_unwrap`]: lint on `.as_ref().unwrap()`

0 files changed, 0 insertions, 0 deletions