This PR touches a lot of parts. But the main changes are changing
`hir_expand::Name` to be raw edition-dependently and only when necessary
(unrelated to how the user originally wrote the identifier),
and changing `is_keyword()` and `is_raw_identifier()` to be edition-aware
(this was done in #17896, but the FIXMEs were fixed here).
It is possible that I missed some cases, but most IDE parts should properly
escape (or not escape) identifiers now.
The rules of thumb are:
- If we show the identifier to the user, its rawness should be determined
by the edition of the edited crate. This is nice for IDE features,
but really important for changes we insert to the source code.
- For tests, I chose `Edition::CURRENT` (so we only have to (maybe) update
tests when an edition becomes stable, to avoid churn).
- For debugging tools (helper methods and logs), I used `Edition::LATEST`.
feat: Implement ATPIT
Resolves#16584
Note: This implementation only works for ATPIT, not for TAIT.
The main hinderence that blocks the later is the defining sites of TAIT can be inner blocks like in;
```rust
type X = impl Default;
mod foo {
fn bar() -> super::X {
()
}
}
```
So, to figure out we are defining it or not, we should recursively probe for nested modules and bodies.
For ATPIT, we can just look into current body because `error[E0401]: can't use 'Self' from outer item` prevent such nested structures;
```rust
trait Foo {
type Item;
fn foo() -> Self::Item;
}
struct Bar;
impl Foo for Bar {
type Item = impl Default;
fn foo() -> Self::Item {
fn bar() -> Self::Item {
^^^^^^^^^^
|
use of `Self` from outer item
refer to the type directly here instead
5
}
bar()
}
}
```
But this implementation does not checks for unification of same ATPIT between different bodies, monomorphization, nor layout for similar reason. (But these can be done with lazyness if we can utilize something like "mutation of interned value" with `db`. I coundn't find such thing but I would appreciate it if such thing exists and you could let me know 😅)
