rollup merge of #20057: nick29581/array-syntax

This does NOT break any existing programs because the `[_, ..n]` syntax is also supported.

Part of #19999

r? @nikomatsakis

1 files changed, 10 insertions, 1 deletions

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 52aa609aeaf..19af118b190 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -1545,7 +1545,7 @@ impl<'a> Parser<'a> {
             self.expect(&token::OpenDelim(token::Bracket));
             let t = self.parse_ty_sum();
 
-            // Parse the `, ..e` in `[ int, ..e ]`
+            // Parse the `; e` in `[ int; e ]`
             // where `e` is a const expression
             let t = match self.maybe_parse_fixed_vstore() {
                 None => TyVec(t),
@@ -1713,6 +1713,9 @@ impl<'a> Parser<'a> {
             self.bump();
             self.bump();
             Some(self.parse_expr())
+        } else if self.check(&token::Semi) {
+            self.bump();
+            Some(self.parse_expr())
         } else {
             None
         }
@@ -2259,6 +2262,12 @@ impl<'a> Parser<'a> {
                         let count = self.parse_expr();
                         self.expect(&token::CloseDelim(token::Bracket));
                         ex = ExprRepeat(first_expr, count);
+                    } else if self.check(&token::Semi) {
+                        // Repeating vector syntax: [ 0; 512 ]
+                        self.bump();
+                        let count = self.parse_expr();
+                        self.expect(&token::CloseDelim(token::Bracket));
+                        ex = ExprRepeat(first_expr, count);
                     } else if self.check(&token::Comma) {
                         // Vector with two or more elements.
                         self.bump();