Chalk's unification can sometimes create lifetime variables, which we
currently don't really deal with, but at least we don't want to leak
them outside of inference.
Should fix#8919.
8856: Use Chalk for unification r=flodiebold a=flodiebold
- use Chalk's unification, get rid of our own `unify`
- rewrite coercion to not use unification internals and to be more analogous to rustc
- fix various coercion bugs
- rewrite handling of obligations, since the old hacky optimization where we noted when an inference variable changes wasn't possible anymore
- stop trying to deeply resolve types all the time during inference, instead only do it shallowly where necessary
Co-authored-by: Florian Diebold <flodiebold@gmail.com>
We can't do the easy hack that we did before anymore, where we kept
track of whether any inference variables changed since the last time we
rechecked obligations. Instead, we store the obligations in
canonicalized form; that way we can easily check the inference variables
to see whether they have changed since the goal was canonicalized.
8873: Implement import-granularity guessing r=matklad a=Veykril
This renames our `MergeBehavior` to `ImportGranularity` as rustfmt has it as the purpose of them are basically the same. `ImportGranularity::Preserve` currently has no specific purpose for us as we don't have an organize imports assist yet, so it currently acts the same as `ImportGranularity::Item`.
We now try to guess the import style on a per file basis and fall back to the user granularity setting if the file has no specific style yet or where it is ambiguous. This can be turned off by setting `import.enforceGranularity` to `true`.
Closes https://github.com/rust-analyzer/rust-analyzer/issues/8870
Co-authored-by: Lukas Tobias Wirth <lukastw97@gmail.com>
