Add span to group.
This appears to fix#14959, but I've never contributed to rust-analyzer before and there were some things that confused me:
- I had to add the `fn byte_range` method to get it to build. This was added to rust in [April](https://github.com/rust-lang/rust/pull/109002), so I don't understand why it wasn't needed until now
- When testing, I ran into the fact that rust recently updated its `METADATA_VERSION`, so I had to test this with nightly-2023-05-20. But then I noticed that rust has its own copy of `rust-analyzer`, and the metadata version bump has already been [handled there](60e95e76d0). So I guess I don't really understand the relationship between the code there and the code here.
internal: Migrate some assists to use the structured snippet API
Migrates the following assists:
- `add_missing_impl_members`
- `extract_type_alias`
As an additional requirement, these assists are also migrated to use the mutable AST API, since otherwise there would be overlapping `Indel` spans
Infer return type for async function in `generate_function`
Part of #10122
In `generate_function` assist, when we infer the return type of async function we're generating, we should retrieve the type of parent await expression rather than the call expression itself.
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
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.
