fix: only generate trait bound for associated types in field types
Given the following definitions:
```rust
trait Trait {
type A;
type B;
type C;
}
#[derive(Clone)]
struct S<T: Trait>
where
T::A: Send,
{
qualified: <T as Trait>::B,
shorthand: T::C,
}
```
we currently expand the derive macro to:
```rust
impl<T> Clone for S<T>
where
T: Trait + Clone,
T::A: Clone,
T::B: Clone,
T::C: Clone,
{ /* ... */ }
```
This does not match how rustc expands it. Specifically, `Clone` bounds for `T::A` and `T::B` should not be generated.
The criteria for associated types to get bound seem to be 1) the associated type appears as part of field types AND 2) it's written in the shorthand form. I have no idea why rustc doesn't consider qualified associated types (there's even a comment that suggests they should be considered; see rust-lang/rust#50730), but it's important to follow rustc.
Emit `'_` for lifetime generics in `HirDisplay`
This makes the generated code not linted by `rust_2018_idioms` lint. But that is an allow by default lint, so should we do this? Maybe we should only do this for `DisplayTarget::SourceCode`?
fix: consider outer binders when folding captured items' type
Fixes#14966
Basically, the crash is caused by us producing a broken type and passing it to chalk: `&dyn for<type> [for<> Implemented(^1.0: A<^0.0>)]` (notice the innermost bound var `^0.0` has no corresponding binder). It's created in `CapturedItemWithoutTy::with_ty()`, which didn't consider outer binders when folding types to replace placeholders with bound variables.
The fix is one-liner, but I've also refactored the surrounding code a little.
- use `DefWithBodyId::as_generic_def_id()`
- add comments on `InferenceResult` invariant
- move local helper function to bottom to comply with style guide
Revert "Add mandatory panic contexts to all threadpool tasks"
Reverts rust-lang/rust-analyzer#14965
This won't quite work actually given the use of `catch_unwind` in some of these
Add mandatory panic contexts to all threadpool tasks
the diagnostics task is panicking I think, but without this you can't really tell because the stack trace ends in a generic iterator fold call instead of something specific.
Fix drop scopes problems in mir
Fix false positives of `need-mut` emerged from #14955
There are still 5 `need-mut` false positives on self, all related to `izip!` macro hygenic issue. I will try to do something about that before monday release.
Fix Assist "replace named generic type with impl trait"
This is a follow-up PR to fix the assist "replace named generic type with impl trait" described in #14626 to filter invalid param types. It integrates the feedback given in PR #14816 .
The change updates the logic to determine when a function parameter is safe to replace a type param with its trait implementation. Some parameter definitions are invalid & should not be replaced by their traits, therefore skipping the assist completely.
First, all usages of the generic type under the cursor are determined. These usage references are checked to see if they occur outside the function parameter list. If an outside reference is found, e.g. in body, return type or where clause, the assist is skipped. All remaining usages need to appear only in the function param list. For each usage the param type is further inspected to see if it's valid. The logic to determine if a function parameter is valid, follows a heuristic and may not cover all possible parameter definitions.
With this change the following param types (as given in [this comment](https://github.com/rust-lang/rust-analyzer/pull/14816#discussion_r1206834603)) are not replaced & therefore skip the assist.
```rust
fn foo<P: Trait>(
_: <P as Trait>::Assoc, // within path type qualifier
_: <() as OtherTrait<P>>::Assoc, // same as above
_: P::Assoc, // associated type shorthand
_: impl OtherTrait<P> // generic arg in impl trait (note that associated type bindings are fine)
_: &dyn Fn(P) // param type and/or return type for Fn* traits
) {}
```
