1815: Support correct `$crate` expansion in macros r=uHOOCCOOHu a=uHOOCCOOHu
This PR makes normal use cases of `$crate` from macros work as expected.
It makes more macros from `std` work. Type inference works well with `panic`, `unimplemented`, `format`, and maybe more.
Sadly that `vec![1, 2, 3]` still not works, but it is not longer an issue about macro.
Screenshot:
Co-authored-by: uHOOCCOOHu <hooccooh1896@gmail.com>
This is only allowed for generic parameters (including `Self` in traits), and
special care needs to be taken to not run into cycles while resolving it,
because we use the where clauses of the generic parameter to find candidates for
the trait containing the associated type, but the where clauses may themselves
contain instances of short-hand associated types.
In some cases this is even fine, e.g. we might have `T: Trait<U::Item>, U:
Iterator`. If there is a cycle, we'll currently panic, which isn't great, but
better than overflowing the stack...
1862: Assoc item resolution refactoring (again) r=flodiebold a=flodiebold
This is #1849, with the associated type selection code removed for now. Handling cycles there will need some more thought.
Co-authored-by: Florian Diebold <flodiebold@gmail.com>
I must confess I don't really understand what this code is trying to
do, but it definitely misreports changes during fixedpoint iteration,
and no tests fail if I remove it, so...
Type-relative paths (`<T>::foo`) also need to work in type context, for example
`<T>::Item` is legal. So rather than returning the type ref from the resolver
function, just check it before.
E.g. `fn foo<T: Iterator>() -> T::Item`. It seems that rustc does this only for
type parameters and only based on their bounds, so we also only consider traits
from bounds.
