Although structs and unions have the same syntax and differ only in
the keyword, re-using the single syntax node for both of them leads to
confusion in practice, and propagates further down the hir in an
upleasent way.
Moreover, static and consts also share syntax, but we use different
nodes for them.
Right now they are handled in `postfix_dot_expr`, but that doesn't allow it to
correctly handle precedence. Integrate it more tightly with the Pratt parser
instead.
Also includes a drive-by fix for parsing `match .. {}`.
Fixes#2242.
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>
