bjoernager/rust
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make error emitted on impl &Trait nicer

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Ezra Shaw 2023-01-14 21:20:20 +13:00
parent ca5d92d789
commit e590b93499
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4 changed files with 154 additions and 5 deletions
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39
compiler/rustc_parse/src/parser/ty.rs
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@ -727,11 +727,13 @@ impl<'a> Parser<'a> {
let mut bounds = Vec::new();
let mut negative_bounds = Vec::new();
// In addition to looping while we find generic bounds:
// We continue even if we find a keyword. This is necessary for error recovery on,
// for example, `impl fn()`. The only keyword that can go after generic bounds is
// `where`, so stop if it's it.
// We also continue if we find types (not traits), again for error recovery.
while self.can_begin_bound()
// Continue even if we find a keyword.
// This is necessary for error recover on, for example, `impl fn()`.
//
// The only keyword that can go after generic bounds is `where`, so stop if it's it.
|| self.token.can_begin_type()
|| (self.token.is_reserved_ident() && !self.token.is_keyword(kw::Where))
{
if self.token.is_keyword(kw::Dyn) {
@ -938,6 +940,35 @@ impl<'a> Parser<'a> {
&& self.look_ahead(1, |tok| tok.kind == TokenKind::OpenDelim(Delimiter::Parenthesis))
&& let Some(path) = self.recover_path_from_fn()
{
path
} else if !self.token.is_path_start() && self.token.can_begin_type() && let Ok(ty) = self.parse_ty_no_plus() {
// Instead of finding a path (a trait), we found a type.
let mut err = self.struct_span_err(ty.span, "expected a trait, found type");
// If we can recover, try to extract a path from the type. Note
// that we do not use the try operator when parsing the type because
// if it fails then we get a parser error which we don't want (we're trying
// to recover from errors, not make more).
let path = if self.may_recover()
&& matches!(ty.kind, TyKind::Ptr(..) | TyKind::Ref(..))
&& let TyKind::Path(_, path) = &ty.peel_refs().kind {
// Just get the indirection part of the type.
let span = ty.span.until(path.span);
err.span_suggestion_verbose(
span,
"consider removing the indirection",
"",
Applicability::MaybeIncorrect,
);
path.clone()
} else {
return Err(err);
};
err.emit();
path
} else {
self.parse_path(PathStyle::Type)?