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feat(expand): emit note for doc comment in macro matcher

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This commit is contained in:
bohan 2023-06-07 00:26:16 +08:00
parent c927743b7b
commit 5eafab30ba
5 changed files with 119 additions and 12 deletions
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46
compiler/rustc_expand/src/mbe/macro_rules.rs
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@ -628,6 +628,40 @@ fn check_lhs_nt_follows(sess: &ParseSess, def: &ast::Item, lhs: &mbe::TokenTree)
// after parsing/expansion. we can report every error in every macro this way.
}
fn is_empty_token_tree(sess: &ParseSess, seq: &mbe::SequenceRepetition) -> bool {
if seq.separator.is_some() {
false
} else {
let mut is_empty = true;
let mut iter = seq.tts.iter().peekable();
while let Some(tt) = iter.next() {
match tt {
mbe::TokenTree::MetaVarDecl(_, _, Some(NonterminalKind::Vis)) => {}
mbe::TokenTree::Token(t @ Token { kind: DocComment(..), .. }) => {
let mut now = t;
while let Some(&mbe::TokenTree::Token(
next @ Token { kind: DocComment(..), .. },
)) = iter.peek()
{
now = next;
iter.next();
}
let span = t.span.to(now.span);
sess.span_diagnostic.span_note_without_error(
span,
"doc comments are ignored in matcher position",
);
}
mbe::TokenTree::Sequence(_, sub_seq)
if (sub_seq.kleene.op == mbe::KleeneOp::ZeroOrMore
|| sub_seq.kleene.op == mbe::KleeneOp::ZeroOrOne) => {}
_ => is_empty = false,
}
}
is_empty
}
}
/// Checks that the lhs contains no repetition which could match an empty token
/// tree, because then the matcher would hang indefinitely.
fn check_lhs_no_empty_seq(sess: &ParseSess, tts: &[mbe::TokenTree]) -> bool {
@ -644,17 +678,7 @@ fn check_lhs_no_empty_seq(sess: &ParseSess, tts: &[mbe::TokenTree]) -> bool {
}
}
TokenTree::Sequence(span, seq) => {
if seq.separator.is_none()
&& seq.tts.iter().all(|seq_tt| match seq_tt {
TokenTree::MetaVarDecl(_, _, Some(NonterminalKind::Vis)) => true,
TokenTree::Token(t) => matches!(t, Token { kind: DocComment(..), .. }),
TokenTree::Sequence(_, sub_seq) => {
sub_seq.kleene.op == mbe::KleeneOp::ZeroOrMore
|| sub_seq.kleene.op == mbe::KleeneOp::ZeroOrOne
}
_ => false,
})
{
if is_empty_token_tree(sess, seq) {
let sp = span.entire();
sess.span_diagnostic.span_err(sp, "repetition matches empty token tree");
return false;