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
rust-analyzer used the token at the cursor after macro expansion
to decide whether to replace the token at the cursor before macro
expansion. In most cases these two are the same but in some cases these
can mismatch which can lead to incorrect replacements.
For example if an ident/expr macro argument is missing rust-analyzer
generates a "missing" identifier as a placeholder, there is only a
brace at the cursor. Therefore, rust-analyzer will incorrectly replace
the macro brace with the completion in that case leading to #14246.
Using the expanded token type was intentional. However, this doesn't
seem to ever be desirable (this is supported by the fact that there
were no tests that relied on this behavior) since the type of edit to
perform should always be determined by the token it's actually applied
to.
Handle trait alias definitions
Part of #2773
This PR adds a bunch of structs and enum variants for trait aliases. Trait aliases should be handled as an independent item because they are semantically distinct from traits.
I basically started by adding `TraitAlias{Id, Loc}` to `hir_def::item_tree` and iterated adding necessary stuffs until compiler stopped complaining what's missing. Let me know if there's still anything I need to add.
I'm opening up this PR for early review and stuff. I'm planning to add tests for IDE functionalities in this PR, but not type-related support, for which I put FIXME notes.
Refactor completions expansion
Depends on https://github.com/rust-lang/rust-analyzer/pull/13384
Diff is unfortunately massive as I changed the functions in the analysis module from associated ones to standalone (unfortunately without an extra commit)
