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Fix handling of unmatched angle brackets in parser

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This commit is contained in:
Fabian Wolff 2021-06-04 22:46:57 +02:00
parent 4e219e6335
commit 6a6a605a61
7 changed files with 120 additions and 37 deletions
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84
compiler/rustc_parse/src/parser/path.rs
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@ -352,49 +352,59 @@ impl<'a> Parser<'a> {
debug!("parse_generic_args_with_leading_angle_bracket_recovery: (snapshotting)");
match self.parse_angle_args() {
Ok(args) => Ok(args),
Err(ref mut e) if is_first_invocation && self.unmatched_angle_bracket_count > 0 => {
// Cancel error from being unable to find `>`. We know the error
// must have been this due to a non-zero unmatched angle bracket
// count.
e.cancel();
Err(mut e) if is_first_invocation && self.unmatched_angle_bracket_count > 0 => {
// Swap `self` with our backup of the parser state before attempting to parse
// generic arguments.
let snapshot = mem::replace(self, snapshot.unwrap());
debug!(
"parse_generic_args_with_leading_angle_bracket_recovery: (snapshot failure) \
snapshot.count={:?}",
snapshot.unmatched_angle_bracket_count,
);
// Eat the unmatched angle brackets.
for _ in 0..snapshot.unmatched_angle_bracket_count {
self.eat_lt();
let all_angle_brackets = (0..snapshot.unmatched_angle_bracket_count)
.fold(true, |a, _| a && self.eat_lt());
if !all_angle_brackets {
// If there are other tokens in between the extraneous `<`s, we cannot simply
// suggest to remove them. This check also prevents us from accidentally ending
// up in the middle of a multibyte character (issue #84104).
let _ = mem::replace(self, snapshot);
Err(e)
} else {
// Cancel error from being unable to find `>`. We know the error
// must have been this due to a non-zero unmatched angle bracket
// count.
e.cancel();
debug!(
"parse_generic_args_with_leading_angle_bracket_recovery: (snapshot failure) \
snapshot.count={:?}",
snapshot.unmatched_angle_bracket_count,
);
// Make a span over ${unmatched angle bracket count} characters.
// This is safe because `all_angle_brackets` ensures that there are only `<`s,
// i.e. no multibyte characters, in this range.
let span =
lo.with_hi(lo.lo() + BytePos(snapshot.unmatched_angle_bracket_count));
self.struct_span_err(
span,
&format!(
"unmatched angle bracket{}",
pluralize!(snapshot.unmatched_angle_bracket_count)
),
)
.span_suggestion(
span,
&format!(
"remove extra angle bracket{}",
pluralize!(snapshot.unmatched_angle_bracket_count)
),
String::new(),
Applicability::MachineApplicable,
)
.emit();
// Try again without unmatched angle bracket characters.
self.parse_angle_args()
}
// Make a span over ${unmatched angle bracket count} characters.
let span = lo.with_hi(lo.lo() + BytePos(snapshot.unmatched_angle_bracket_count));
self.struct_span_err(
span,
&format!(
"unmatched angle bracket{}",
pluralize!(snapshot.unmatched_angle_bracket_count)
),
)
.span_suggestion(
span,
&format!(
"remove extra angle bracket{}",
pluralize!(snapshot.unmatched_angle_bracket_count)
),
String::new(),
Applicability::MachineApplicable,
)
.emit();
// Try again without unmatched angle bracket characters.
self.parse_angle_args()
}
Err(e) => Err(e),
}