Add BOX_KW to PATTERN_FIRST

Author: ecstatic-morse

crates/ra_parser/src/grammar/patterns.rs

@@ -2,7 +2,7 @@ use super::*;
 
 pub(super) const PATTERN_FIRST: TokenSet = expressions::LITERAL_FIRST
     .union(paths::PATH_FIRST)
-    .union(token_set![REF_KW, MUT_KW, L_PAREN, L_BRACK, AMP, UNDERSCORE, MINUS]);
+    .union(token_set![BOX_KW, REF_KW, MUT_KW, L_PAREN, L_BRACK, AMP, UNDERSCORE, MINUS]);
 
 pub(super) fn pattern(p: &mut Parser) {
     pattern_r(p, PAT_RECOVERY_SET);