4246: Validate uses of self and super r=matklad a=djrenren
This change follows on the validation of the `crate` keyword in paths. It verifies the following things:
`super`:
- May only be preceded by other `super` segments
- If in a `UseItem` then all semantically preceding paths also consist only of `super`
`self`
- May only be the start of a path
Just a note, a couple times while working on this I found myself really wanting a Visitor of some sort so that I could traverse descendants while skipping sub-trees that are unimportant. Iterators don't really work for this, so as you can see I reached for recursion. Considering paths are generally small a fancy debounced visitor probably isn't important but figured I'd say something in case we had something like this lying around and I wasn't using it.
Co-authored-by: John Renner <john@jrenner.net>
We treat macro calls as expressions (there's appropriate Into impl),
which causes problem if there's expresison and non-expression macro in
the same node (like in the match arm).
We fix this problem by nesting macor patterns into another node (the
same way we nest path into PathExpr or PathPat). Ideally, we probably
should add a similar nesting for macro expressions, but that needs
some careful thinking about macros in blocks: `{ am_i_expression!() }`.
3062: Implement slice pattern AST > HIR lowering r=jplatte a=jplatte
WIP. The necessary changes for parsing are implemented, but actual inference is not yet. Just wanted to upload what I've got so far so it doesn't get duplicated :)
Will fix#3043
Co-authored-by: Jonas Platte <jplatte+git@posteo.de>
