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Auto merge of #117289 - estebank:issue-72298, r=cjgillot

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Account for `ref` and `mut` in the wrong place for pattern ident renaming

If the user writes `S { ref field: name }` instead of `S { field: ref name }`, we suggest the correct code.

Fix #72298.
This commit is contained in:
bors 2023-11-01 18:39:01 +00:00
commit b0a07595b5
4 changed files with 127 additions and 1 deletions
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34
compiler/rustc_parse/src/parser/pat.rs
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@ -967,11 +967,12 @@ impl<'a> Parser<'a> {
// check that a comma comes after every field
if !ate_comma {
let err = ExpectedCommaAfterPatternField { span: self.token.span }
let mut err = ExpectedCommaAfterPatternField { span: self.token.span }
.into_diagnostic(&self.sess.span_diagnostic);
if let Some(mut delayed) = delayed_err {
delayed.emit();
}
self.recover_misplaced_pattern_modifiers(&fields, &mut err);
return Err(err);
}
ate_comma = false;
@ -1109,6 +1110,37 @@ impl<'a> Parser<'a> {
Ok((fields, etc))
}
/// If the user writes `S { ref field: name }` instead of `S { field: ref name }`, we suggest
/// the correct code.
fn recover_misplaced_pattern_modifiers(
&self,
fields: &ThinVec<PatField>,
err: &mut DiagnosticBuilder<'a, ErrorGuaranteed>,
) {
if let Some(last) = fields.iter().last()
&& last.is_shorthand
&& let PatKind::Ident(binding, ident, None) = last.pat.kind
&& binding != BindingAnnotation::NONE
&& self.token == token::Colon
// We found `ref mut? ident:`, try to parse a `name,` or `name }`.
&& let Some(name_span) = self.look_ahead(1, |t| t.is_ident().then(|| t.span))
&& self.look_ahead(2, |t| {
t == &token::Comma || t == &token::CloseDelim(Delimiter::Brace)
})
{
let span = last.pat.span.with_hi(ident.span.lo());
// We have `S { ref field: name }` instead of `S { field: ref name }`
err.multipart_suggestion(
"the pattern modifiers belong after the `:`",
vec![
(span, String::new()),
(name_span.shrink_to_lo(), binding.prefix_str().to_string()),
],
Applicability::MachineApplicable,
);
}
}
/// Recover on `...` or `_` as if it were `..` to avoid further errors.
/// See issue #46718.
fn recover_bad_dot_dot(&self) {