Add doc-alias based completion
Closes#14406.
I adapted the parsing code from the CfgExpr parsing code, maybe there's a better abstraction for both, or attribute parsing in general. It also includes `doc(hidden)`-parsing, which means it could replace the other function.
There are a few tests for parsing.
`process_all_names` changed the most, I added some docs there to explain what happens.
Many call sites just pass an empy vec to `add_path_resolution`'s `doc_aliases`, since either it doesn't make sense to pass anything (e.g. visibility completion) or I don't know where to get them from. Shouldn't really matter, as it will just not show aliases if the vec is empty and we can extend alias completion in these cases later.
I added two tests in `special.rs` for struct name completion (which was the main thing I wanted). I also tried function and field names, but these don't work yet. I want to add those in a follow-up PR.
Normalize associated types in paths in expressions
Part of #14393
When we resolve paths in expressions (either path expressions or paths in struct expressions), there's a need of projection normalization, which `TyLoweringContext` cannot do on its own. We've been properly applying normalization for paths in struct expressions without type anchor, but not for others:
```rust
enum E {
S { v: i32 }
Empty,
}
impl Foo for Bar {
type Assoc = E;
fn foo() {
let _ = Self::Assoc::S { v: 42 }; // path in struct expr without type anchor; we already support this
let _ = <Self>::Assoc::S { v: 42 }; // path in struct expr with type anchor; resolves with this PR
let _ = Self::Assoc::Empty; // path expr; resolves with this PR
}
}
```
With this PR we correctly resolve the whole path, but we need some more tweaks in HIR and/or IDE layers to properly resolve a qualifier (prefix) of such paths and provide IDE features that are pointed out in #14393 to be currently broken.
Expand Macro Recursively: don't append "!" to non-bang macro name
When we run `Expand Macro Recursively`, we prepend a comment "Recursive expansion of foo! macro" to the expansion result. I've noticed we unconditionally render the macro name with "!" and, while super subtle, I feel a bit awkward when the macro is either a derive or attribute macro.
Limited syntax support for return type notations (RTN)
Experimental RTN bound support was recently merged into rustc (https://github.com/rust-lang/rust/issues/109417), the goal of this PR is to allow experimentation without syntax errors everywhere.
The parsing implemented currently aligns with the state of the tracking issue, it only supports the form `T<foo(..): Bounds>`. The parser always checks for the presence of `..` to disambiguate from `Fn*()` types, this is not ideal but I didn't want to spend too much time as it is an experimental feature.
