tweak wording of mismatched delimiter errors
This PR improves the wording of the "incorrect delimiter" error messages. Here's a quick rationale:
- *"un-closed" -> "unclosed"*: "unclosed" is valid English, so there's no need to hyphenate the prefix. This should be pretty uncontroversial, I think.
- *"close delimiter" -> "closing delimiter"*: In my anecdotal experience, I've always heard "closing delimiter" or "closing parenthesis". In addition, the codebase already uses this terminology in comments and function names more than "close delimiter", which could indicate that it's more intuitive.
- "incorrect delimiter" -> "mismatched delimiter": "Incorrect delimiter" is vague; why is it incorrect? "mismatched" clearly indicates why the delimiter is causing the error.
r? @estebank
Nix reexports from `rustc_span` in `syntax`
Remove reexports `syntax::{source_map, symbol, edition}` and use `rustc_span` paths directly.
r? @petrochenkov
parser: reduce diversity in error handling mechanisms
Instead of having e.g. `span_err`, `fatal`, etc., we prefer to move towards uniformly using `struct_span_err` thus making it harder to emit fatal and/or unstructured diagnostics.
This PR also de-fatalizes some diagnostics.
r? @estebank
Refactor expression parsing thoroughly
Based on https://github.com/rust-lang/rust/pull/66994 together with which this has refactored basically the entirety of `expr.rs`.
r? @estebank
Initial implementation of `#![feature(bindings_after_at)]`
Following up on #16053, under the gate `#![feature(bindings_after_at)]`, `x @ Some(y)` is allowed subject to restrictions necessary for soundness.
The implementation and test suite should be fairly complete now.
One aspect that is not covered is the interaction with nested `#![feature(or_patterns)]`.
This is not possible to test at the moment in a good way because that feature has not progressed sufficiently and has fatal errors in MIR building. We should make sure to add such tests before we stabilize both features (but shipping one of them is fine).
r? @pnkfelix
cc @nikomatsakis @matthewjasper @pcwalton
cc https://github.com/rust-lang/rust/issues/65490
