Accept trailing commas in struct patterns

We decided in the 12/10/13 weekly meeting that trailing commas should be
accepted pretty much anywhere. They are currently not allowed in struct
patterns, and this commit adds support for that.

Closes #10392

1 files changed, 7 insertions, 2 deletions

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 35ea06d62ca..729d0320435 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -2800,8 +2800,13 @@ impl Parser {
         let mut etc = false;
         let mut first = true;
         while *self.token != token::RBRACE {
-            if first { first = false; }
-            else { self.expect(&token::COMMA); }
+            if first {
+                first = false;
+            } else {
+                self.expect(&token::COMMA);
+                // accept trailing commas
+                if *self.token == token::RBRACE { break }
+            }
 
             etc = *self.token == token::UNDERSCORE || *self.token == token::DOTDOT;
             if *self.token == token::UNDERSCORE {