bjoernager/rust
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Switch existential_type to type_alias_impl_trait

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This commit is contained in:
varkor 2019-07-30 00:11:50 +01:00
parent 435236b887
commit 87738fe834
7 changed files with 52 additions and 61 deletions
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25
src/libsyntax/parse/parser.rs
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@ -6805,40 +6805,29 @@ impl<'a> Parser<'a> {
Ok(self.mk_item(lo.to(prev_span), invalid, ItemKind::ForeignMod(m), visibility, attrs))
}
/// Parses `type Foo = Bar;`
/// or
/// `existential type Foo: Bar;`
/// or
/// `return `None``
/// Parses `type Foo = Bar;` or returns `None`
/// without modifying the parser state.
fn eat_type(&mut self) -> Option<PResult<'a, (Ident, AliasKind, ast::Generics)>> {
// This parses the grammar:
// Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
if self.check_keyword(kw::Type) ||
self.check_keyword(kw::Existential) &&
self.is_keyword_ahead(1, &[kw::Type]) {
let existential = self.eat_keyword(kw::Existential);
assert!(self.eat_keyword(kw::Type));
Some(self.parse_existential_or_alias(existential))
if self.eat_keyword(kw::Type) {
Some(self.parse_type_alias())
} else {
None
}
}
/// Parses a type alias or existential type.
fn parse_existential_or_alias(
&mut self,
existential: bool,
) -> PResult<'a, (Ident, AliasKind, ast::Generics)> {
fn parse_type_alias(&mut self) -> PResult<'a, (Ident, AliasKind, ast::Generics)> {
let ident = self.parse_ident()?;
let mut tps = self.parse_generics()?;
tps.where_clause = self.parse_where_clause()?;
let alias = if existential {
self.expect(&token::Colon)?;
self.expect(&token::Eq)?;
let alias = if self.check_keyword(kw::Impl) {
self.bump();
let bounds = self.parse_generic_bounds(Some(self.prev_span))?;
AliasKind::Existential(bounds)
} else {
self.expect(&token::Eq)?;
let ty = self.parse_ty()?;
AliasKind::Weak(ty)
};