`make::match_arm` should take a single `ast::Pat`, and callers can handle creating an `ast::OrPat` if need be. It should also take a proper `ast::MatchGuard`, instead of making one itself.
And implement addons as necessary.
There are many more makers to be moved, and I'm not completely satisfied with this (due to the ease of making a mistake in the AST structure, and slightly less but also because of the need to remember whitespaces), but this is already enough to see how this will look like.
The diagnostic implemented is a simple one (E0109). It serves as a test for the new foundation.
This commit only implements diagnostics for type in bodies and body-carrying signatures; the next commit will include diagnostics in the rest of the things.
Also fix one weird bug that was detected when implementing this that caused `Fn::(A, B) -> C` (which is a valid, if bizarre, alternative syntax to `Fn(A, B) -> C` to lower incorrectly.
And also fix a maybe-bug where parentheses were sneaked into a code string needlessly; this was not detected until now because the parentheses were removed (by the make-AST family API), but with a change in this commit they are now inserted. So fix that too.
internal: Replace once_cell with std's recently stabilized OnceCell/Lock and LazyCell/Lock
This doesn't get rid of the once_cell dependency, unfortunately, since we have dependencies that use it, but it's a nice to do cleanup. And when our deps will eventually get rid of once_cell we will get rid of it for free.
This doesn't get rid of the once_cell dependency, unfortunately, since we have dependencies that use it, but it's a nice to do cleanup. And when our deps will eventually get rid of once_cell we will get rid of it for free.
Clean up a few minor refs in `format!` macro, as it has a performance cost. Apparently the compiler is unable to inline `format!("{}", &variable)`, and does a run-time double-reference instead (format macro already does one level referencing). Inlining format args prevents accidental `&` misuse.
Separate into create and apply edit
Rename usages
Hacky name map
Add more tests
Handle non-exhaustive
Add some more TODOs
Private fields
Use todo
Nesting
Improve rest token generation
Cleanup
Doc -> regular comment
Support mut
