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.
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2 changed files with 40 additions and 1 deletions
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@ -350,7 +350,16 @@ pub fn parse(sess: &ParseSess,
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sp_lo: sp.lo
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});
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}
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MatchNonterminal(_,_,_) => { bb_eis.push(ei) }
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MatchNonterminal(_,_,_) => {
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// Built-in nonterminals never start with these tokens,
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// so we can eliminate them from consideration.
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match tok {
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token::RPAREN |
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token::RBRACE |
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token::RBRACKET => {},
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_ => bb_eis.push(ei)
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}
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}
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MatchTok(ref t) => {
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let mut ei_t = ei.clone();
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if token_name_eq(t,&tok) {
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