This adds the type inference to Union types and add a small test case
for it, ensuring it keeps working in future.
Fixes: #5277
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
If the first type parameter gets inferred, that's still not handled correctly;
it'll require some more refactoring: E.g. if we have `Thing<T, F=fn() -> T>` and
then instantiate `Thing<_>`, that gets turned into `Thing<_, fn() -> _>` before
the `_` is instantiated into a type variable -- so afterwards, we have two type
variables without any connection to each other.
4651: Use first match branch in case of type mismatch, not last r=kjeremy a=flodiebold
The comment says this was intentional, but I do agree with #4304 that it makes
more sense the other way around (for if/else as well).
Fixes#4304.
Co-authored-by: Florian Diebold <florian.diebold@freiheit.com>
This fixes an issue where the following code sample would fail to infer
the type contained in the option:
```rust
fn main() {
let mut end = None; // TODO: Fix inference for this in RA
loop {
end = Some(true);
}
}
```
Divergence here means that for some reason, the end of a block will not be
reached. We tried to model this just using the never type, but that doesn't work
fully (e.g. in `let x = { loop {}; "foo" };` x should still have type `&str`);
so this introduces a `diverges` flag that the type checker keeps track of, like
rustc does.
