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extract parse_dyn_ty

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This commit is contained in:
Mazdak Farrokhzad 2019-12-08 08:38:23 +01:00
parent edb7b96c84
commit b7071f2bc0
1 changed files with 27 additions and 13 deletions
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40
src/librustc_parse/parser/ty.rs
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@ -108,20 +108,14 @@ impl<'a> Parser<'a> {
}
} else if self.eat_keyword(kw::Impl) {
self.parse_impl_ty(&mut impl_dyn_multi)?
} else if self.check_keyword(kw::Dyn) &&
(self.token.span.rust_2018() ||
self.look_ahead(1, |t| t.can_begin_bound() &&
!can_continue_type_after_non_fn_ident(t))) {
self.bump(); // `dyn`
// Always parse bounds greedily for better error recovery.
let bounds = self.parse_generic_bounds(None)?;
impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn)
} else if self.check(&token::Question) ||
self.check_lifetime() && self.look_ahead(1, |t| t.is_like_plus()) {
} else if self.is_explicit_dyn_type() {
self.parse_dyn_ty(&mut impl_dyn_multi)?
} else if self.check(&token::Question)
|| self.check_lifetime() && self.look_ahead(1, |t| t.is_like_plus())
{
// Bound list (trait object type)
TyKind::TraitObject(self.parse_generic_bounds_common(allow_plus, None)?,
TraitObjectSyntax::None)
let bounds = self.parse_generic_bounds_common(allow_plus, None)?;
TyKind::TraitObject(bounds, TraitObjectSyntax::None)
} else if self.eat_lt() {
// Qualified path
let (qself, path) = self.parse_qpath(PathStyle::Type)?;
@ -316,6 +310,26 @@ impl<'a> Parser<'a> {
Ok(TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds))
}
/// Is a `dyn B0 + ... + Bn` type allowed here?
fn is_explicit_dyn_type(&mut self) -> bool {
self.check_keyword(kw::Dyn)
&& (self.token.span.rust_2018()
|| self.look_ahead(1, |t| {
t.can_begin_bound() && !can_continue_type_after_non_fn_ident(t)
}))
}
/// Parses a `dyn B0 + ... + Bn` type.
///
/// Note that this does *not* parse bare trait objects.
fn parse_dyn_ty(&mut self, impl_dyn_multi: &mut bool) -> PResult<'a, TyKind> {
self.bump(); // `dyn`
// Always parse bounds greedily for better error recovery.
let bounds = self.parse_generic_bounds(None)?;
*impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn))
}
pub(super) fn parse_generic_bounds(&mut self,
colon_span: Option<Span>) -> PResult<'a, GenericBounds> {
self.parse_generic_bounds_common(true, colon_span)