From fc60797f7f3079288bdd1717dedbb885eaf1dbfa Mon Sep 17 00:00:00 2001 From: Vadim Chugunov Date: Mon, 6 Oct 2014 23:15:12 -0700 Subject: Fix the most egregious instances of "local ambiguity: multiple parsing options..." error in macros, which often occurs when trying to match parts of Rust syntax. For example, this matcher: `fn $name:ident( $($param:ident : $pty:ty),* )` would fail when parsing `fn foo()`, because macro parser wouldn't realize that an ident cannot start with `)`. This resolves #5902, and at least partially mitigates #9364 and #3232. --- src/libsyntax/ext/tt/macro_parser.rs | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'src/libsyntax') diff --git a/src/libsyntax/ext/tt/macro_parser.rs b/src/libsyntax/ext/tt/macro_parser.rs index 090b39eee47..88376108fec 100644 --- a/src/libsyntax/ext/tt/macro_parser.rs +++ b/src/libsyntax/ext/tt/macro_parser.rs @@ -350,7 +350,16 @@ pub fn parse(sess: &ParseSess, sp_lo: sp.lo }); } - MatchNonterminal(_,_,_) => { bb_eis.push(ei) } + MatchNonterminal(_,_,_) => { + // Built-in nonterminals never start with these tokens, + // so we can eliminate them from consideration. + match tok { + token::RPAREN | + token::RBRACE | + token::RBRACKET => {}, + _ => bb_eis.push(ei) + } + } MatchTok(ref t) => { let mut ei_t = ei.clone(); if token_name_eq(t,&tok) { -- cgit 1.4.1-3-g733a5