1848: Parse `..` as a full pattern r=matklad a=ecstatic-morse
Resolves#1479.
This PR implements [RFC 2707](https://github.com/rust-lang/rfcs/pull/2707) in the parser. It introduces a new `DotDotPat` AST node modeled on `PlaceholderPat` and changes the parsing of tuple and slice patterns to conform to the RFC.
Notably, this PR does *not* change the resulting AST when `..` appears in a struct pattern (e.g. `Struct { a, b: c, .. }`). I *think* this is the behavior mandated by RFC 2707, but someone should confirm this.
Co-authored-by: Dylan MacKenzie <ecstaticmorse@gmail.com>
Parser has the invariant that `{}` are balanced.
Previous code tried (unsucesfuly) maintain the same invariant for
`$()` as well, but it was done in a rather ad-hoc manner: it's not at
all obvious that it is possible to maintain both invariants!
Named structs can have `box` patterns that will bind to their fields.
This is similar to the behavior of the `ref` and `mut` fields, but is at
least a little bit surprising.
1661: Parse function parameters attributes r=matklad a=eupn
Fixes#1397. The [RFC-2565](https://github.com/rust-lang/rfcs/blob/master/text/2565-formal-function-parameter-attributes.md) specifies `#[attributes]` to function parameters:
```rust
fn foo(#[attr] a, #[unused] b, #[must_use] ...) {
// ...
}
```
This PR adds those attributes into grammar and to the parser, extending corresponding inline tests.
Co-authored-by: Evgenii P <eupn@protonmail.com>
This wasn't a right decision in the first place, the feature flag was
broken in the last rustfmt release, and syntax highlighting of imports
is more important anyway
Array members are allow to have attributes such as `#[cfg]`.
This is a bit tricky as we don't know if the first expression is an
initializer or a member until we encounter a `;`. This reuses a trick
from `stmt` where we remember if we saw an attribute and then raise an
error if the first expression ends up being an initializer.
This isn't perfect as the error isn't correctly located on the attribute
or initializer; it ends up immediately after the `;`.
