bjoernager/rust
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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.

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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.
This commit is contained in:
Vadim Chugunov 2014-10-06 23:15:12 -07:00
parent e62ef37cfa
commit fc60797f7f
2 changed files with 40 additions and 1 deletions
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11
src/libsyntax/ext/tt/macro_parser.rs
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@ -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) {