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### What it does
Checks for methods with certain name prefixes and which
doesn't match how self is taken. The actual rules are:
|Prefix |Postfix |`self` taken | `self` type |
|-------|------------|-------------------------------|--------------|
|`as_` | none |`&self` or `&mut self` | any |
|`from_`| none | none | any |
|`into_`| none |`self` | any |
|`is_` | none |`&mut self` or `&self` or none | any |
|`to_` | `_mut` |`&mut self` | any |
|`to_` | not `_mut` |`self` | `Copy` |
|`to_` | not `_mut` |`&self` | not `Copy` |
Note: Clippy doesn't trigger methods with `to_` prefix in:
- Traits definition.
Clippy can not tell if a type that implements a trait is `Copy` or not.
- Traits implementation, when `&self` is taken.
The method signature is controlled by the trait and often `&self` is required for all types that implement the trait
(see e.g. the `std::string::ToString` trait).
Clippy allows `Pin<&Self>` and `Pin<&mut Self>` if `&self` and `&mut self` is required.
Please find more info here:
https://rust-lang.github.io/api-guidelines/naming.html#ad-hoc-conversions-follow-as_-to_-into_-conventions-c-conv
### Why is this bad?
Consistency breeds readability. If you follow the
conventions, your users won't be surprised that they, e.g., need to supply a
mutable reference to a `as_..` function.
### Example
```
impl X {
fn as_str(self) -> &'static str {
// ..
}
}
```
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