internal: Format let-else
As nightly finally got support for it I went ahead and formatted r-a with the latest nightly, then with the latest stable (in case other stuff changed)
doc(alias)-based completion round 2
Follow-up on #14433
We can now complete fields, functions and some use/mods.
Flyimports don't behave, I don't really have the time to understand the structure there either.
While reading the flyimport code, I removed one method only used there, the closure-tree was a bit confusing, I can revert that if you want.
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.
feat: show only missing variant suggestion for enums in patterns completion and bump them in list too
Fixes#12438
### Points to help in review:
- This PR can be reviewed commit wise, first commit is about bumping enum variant completions up in the list of completions and second commit is about only showing enum variants which are not complete
- I am calculating missing variants in analysis.rs by firstly locating the enum and then comparing each of it's variant's name and checking if arm string already contains that name, this is kinda hacky but I didn't want to implement complete missing_arms assist here as that would have been too bulky to run on each completion cycle ( if we can improve this somehow would appreciate some inputs on it )
### Output:
https://user-images.githubusercontent.com/49019259/208245540-57d7321b-b275-477e-bef0-b3a1ff8b7040.mov
Relevant Zulip Discussion: https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Frust-analyzer/topic/Issue.20.2312438
