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Auto merge of #94495 - estebank:missing-closing-gt, r=jackh726

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Provide suggestion for missing `>` in a type parameter list

When encountering an inproperly terminated type parameter list, provide
a suggestion to close it after the last non-constraint type parameter
that was successfully parsed.

Fix #94058.
This commit is contained in:
bors 2022-03-27 18:55:58 +00:00
commit ab0c2e18dc
20 changed files with 208 additions and 14 deletions
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35
compiler/rustc_parse/src/parser/path.rs
View file

@ -272,7 +272,23 @@ impl<'a> Parser<'a> {
lo,
ty_generics,
)?;
self.expect_gt()?;
self.expect_gt().map_err(|mut err| {
// Attempt to find places where a missing `>` might belong.
if let Some(arg) = args
.iter()
.rev()
.skip_while(|arg| matches!(arg, AngleBracketedArg::Constraint(_)))
.next()
{
err.span_suggestion_verbose(
arg.span().shrink_to_hi(),
"you might have meant to end the type parameters here",
">".to_string(),
Applicability::MaybeIncorrect,
);
}
err
})?;
let span = lo.to(self.prev_token.span);
AngleBracketedArgs { args, span }.into()
} else {
@ -462,6 +478,23 @@ impl<'a> Parser<'a> {
while let Some(arg) = self.parse_angle_arg(ty_generics)? {
args.push(arg);
if !self.eat(&token::Comma) {
if self.token.kind == token::Semi
&& self.look_ahead(1, |t| t.is_ident() || t.is_lifetime())
{
// Add `>` to the list of expected tokens.
self.check(&token::Gt);
// Handle `,` to `;` substitution
let mut err = self.unexpected::<()>().unwrap_err();
self.bump();
err.span_suggestion_verbose(
self.prev_token.span.until(self.token.span),
"use a comma to separate type parameters",
", ".to_string(),
Applicability::MachineApplicable,
);
err.emit();
continue;
}
if !self.token.kind.should_end_const_arg() {
if self.handle_ambiguous_unbraced_const_arg(&mut args)? {
// We've managed to (partially) recover, so continue trying to parse