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fix nested matchers with ?

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This commit is contained in:
mark 2019-01-14 15:50:33 -06:00
parent 14ea6e50c1
commit 6046be42ab
1 changed files with 10 additions and 4 deletions

14
src/libsyntax/ext/tt/macro_rules.rs

@ -435,7 +435,8 @@ fn check_lhs_no_empty_seq(sess: &ParseSess, tts: &[quoted::TokenTree]) -> bool {
match *seq_tt {
TokenTree::MetaVarDecl(_, _, id) => id.name == "vis",
TokenTree::Sequence(_, ref sub_seq) =>
sub_seq.op == quoted::KleeneOp::ZeroOrMore,
sub_seq.op == quoted::KleeneOp::ZeroOrMore
|| sub_seq.op == quoted::KleeneOp::ZeroOrOne,
_ => false,
}
}) {
@ -543,7 +544,10 @@ impl FirstSets {
}
// Reverse scan: Sequence comes before `first`.
if subfirst.maybe_empty || seq_rep.op == quoted::KleeneOp::ZeroOrMore {
if subfirst.maybe_empty
|| seq_rep.op == quoted::KleeneOp::ZeroOrMore
|| seq_rep.op == quoted::KleeneOp::ZeroOrOne
{
// If sequence is potentially empty, then
// union them (preserving first emptiness).
first.add_all(&TokenSet { maybe_empty: true, ..subfirst });
@ -591,8 +595,10 @@ impl FirstSets {
assert!(first.maybe_empty);
first.add_all(subfirst);
if subfirst.maybe_empty ||
seq_rep.op == quoted::KleeneOp::ZeroOrMore {
if subfirst.maybe_empty
|| seq_rep.op == quoted::KleeneOp::ZeroOrMore
|| seq_rep.op == quoted::KleeneOp::ZeroOrOne
{
// continue scanning for more first
// tokens, but also make sure we
// restore empty-tracking state