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Rollup merge of #117891 - compiler-errors:recover-for-dyn, r=davidtwco

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Recover `dyn` and `impl` after `for<...>`

Recover `dyn` and `impl` after `for<...>` in types. Reuses the logic for parsing bare trait objects, so it doesn't fix cases like `for<'a> dyn Trait + dyn Trait` or anything, but that seems somewhat of a different issue.

Parsing recovery logic is a bit involved, but I couldn't find a way to simplify it.

Fixes #117882
This commit is contained in:
Michael Goulet 2023-11-19 19:14:33 -08:00 • committed by GitHub
commit a7f805d277
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5 changed files with 95 additions and 3 deletions
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40
compiler/rustc_parse/src/parser/ty.rs
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@ -287,6 +287,7 @@ impl<'a> Parser<'a> {
// Function pointer type
self.parse_ty_bare_fn(lo, ThinVec::new(), None, recover_return_sign)?
} else if self.check_keyword(kw::For) {
let for_span = self.token.span;
// Function pointer type or bound list (trait object type) starting with a poly-trait.
// `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
// `for<'lt> Trait1<'lt> + Trait2 + 'a`
@ -299,9 +300,42 @@ impl<'a> Parser<'a> {
recover_return_sign,
)?
} else {
let path = self.parse_path(PathStyle::Type)?;
let parse_plus = allow_plus == AllowPlus::Yes && self.check_plus();
self.parse_remaining_bounds_path(lifetime_defs, path, lo, parse_plus)?
// Try to recover `for<'a> dyn Trait` or `for<'a> impl Trait`.
if self.may_recover()
&& (self.eat_keyword_noexpect(kw::Impl) || self.eat_keyword_noexpect(kw::Dyn))
{
let kw = self.prev_token.ident().unwrap().0.name;
let mut err = self.sess.create_err(errors::TransposeDynOrImpl {
span: self.prev_token.span,
kw: kw.as_str(),
sugg: errors::TransposeDynOrImplSugg {
removal_span: self.prev_token.span.with_hi(self.token.span.lo()),
insertion_span: for_span.shrink_to_lo(),
kw: kw.as_str(),
},
});
let path = self.parse_path(PathStyle::Type)?;
let parse_plus = allow_plus == AllowPlus::Yes && self.check_plus();
let kind =
self.parse_remaining_bounds_path(lifetime_defs, path, lo, parse_plus)?;
// Take the parsed bare trait object and turn it either
// into a `dyn` object or an `impl Trait`.
let kind = match (kind, kw) {
(TyKind::TraitObject(bounds, _), kw::Dyn) => {
TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn)
}
(TyKind::TraitObject(bounds, _), kw::Impl) => {
TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds)
}
_ => return Err(err),
};
err.emit();
kind
} else {
let path = self.parse_path(PathStyle::Type)?;
let parse_plus = allow_plus == AllowPlus::Yes && self.check_plus();
self.parse_remaining_bounds_path(lifetime_defs, path, lo, parse_plus)?
}
}
} else if self.eat_keyword(kw::Impl) {
self.parse_impl_ty(&mut impl_dyn_multi)?