Merge #1848

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 <[email protected]>

1 files changed, 2 insertions, 1 deletions

diff --git a/crates/ra_syntax/test_data/parser/ok/0035_weird_exprs.txt b/crates/ra_syntax/test_data/parser/ok/0035_weird_exprs.txt
index c18e3c329..3326ab2ae 100644
--- a/crates/ra_syntax/test_data/parser/ok/0035_weird_exprs.txt
+++ b/crates/ra_syntax/test_data/parser/ok/0035_weird_exprs.txt
@@ -1656,7 +1656,8 @@ SOURCE_FILE@[0; 3813)
                         PARAM@[2952; 2962)
                           TUPLE_PAT@[2952; 2956)
                             L_PAREN@[2952; 2953) "("
-                            DOTDOT@[2953; 2955) ".."
+                            DOT_DOT_PAT@[2953; 2955)
+                              DOTDOT@[2953; 2955) ".."
                             R_PAREN@[2955; 2956) ")"
                           COLON@[2956; 2957) ":"
                           TUPLE_TYPE@[2957; 2962)