Switch existential_type to type_alias_impl_trait
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435236b887
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87738fe834
@ -453,9 +453,6 @@ declare_features! (
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// Allows `#[doc(alias = "...")]`.
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(active, doc_alias, "1.27.0", Some(50146), None),
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// Allows defining `existential type`s.
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(active, existential_type, "1.28.0", Some(63063), None),
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// Allows inconsistent bounds in where clauses.
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(active, trivial_bounds, "1.28.0", Some(48214), None),
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@ -560,6 +557,9 @@ declare_features! (
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// Allows `[x; N]` where `x` is a constant (RFC 2203).
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(active, const_in_array_repeat_expressions, "1.37.0", Some(49147), None),
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// Allows `impl Trait` to be used inside type aliases (RFC 2515).
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(active, type_alias_impl_trait, "1.38.0", Some(63063), None),
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// -------------------------------------------------------------------------
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// feature-group-end: actual feature gates
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// -------------------------------------------------------------------------
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@ -625,6 +625,9 @@ declare_features! (
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(removed, dropck_parametricity, "1.38.0", Some(28498), None, None),
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(removed, await_macro, "1.38.0", Some(50547), None,
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Some("subsumed by `.await` syntax")),
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// Allows defining `existential type`s.
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(removed, existential_type, "1.38.0", Some(63063), None,
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Some("removed in favor of `#![feature(type_alias_impl_trait)]`")),
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// -------------------------------------------------------------------------
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// feature-group-end: removed features
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@ -2017,7 +2020,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
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ast::ItemKind::Existential(..) => {
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gate_feature_post!(
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&self,
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existential_type,
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type_alias_impl_trait,
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i.span,
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"existential types are unstable"
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);
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@ -2246,7 +2249,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
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ast::ImplItemKind::Existential(..) => {
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gate_feature_post!(
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&self,
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existential_type,
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type_alias_impl_trait,
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ii.span,
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"existential types are unstable"
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);
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@ -6805,40 +6805,29 @@ impl<'a> Parser<'a> {
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Ok(self.mk_item(lo.to(prev_span), invalid, ItemKind::ForeignMod(m), visibility, attrs))
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}
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/// Parses `type Foo = Bar;`
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/// or
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/// `existential type Foo: Bar;`
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/// or
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/// `return `None``
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/// Parses `type Foo = Bar;` or returns `None`
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/// without modifying the parser state.
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fn eat_type(&mut self) -> Option<PResult<'a, (Ident, AliasKind, ast::Generics)>> {
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// This parses the grammar:
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// Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
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if self.check_keyword(kw::Type) ||
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self.check_keyword(kw::Existential) &&
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self.is_keyword_ahead(1, &[kw::Type]) {
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let existential = self.eat_keyword(kw::Existential);
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assert!(self.eat_keyword(kw::Type));
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Some(self.parse_existential_or_alias(existential))
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if self.eat_keyword(kw::Type) {
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Some(self.parse_type_alias())
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} else {
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None
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}
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}
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/// Parses a type alias or existential type.
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fn parse_existential_or_alias(
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&mut self,
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existential: bool,
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) -> PResult<'a, (Ident, AliasKind, ast::Generics)> {
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fn parse_type_alias(&mut self) -> PResult<'a, (Ident, AliasKind, ast::Generics)> {
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let ident = self.parse_ident()?;
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let mut tps = self.parse_generics()?;
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tps.where_clause = self.parse_where_clause()?;
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let alias = if existential {
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self.expect(&token::Colon)?;
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self.expect(&token::Eq)?;
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let alias = if self.check_keyword(kw::Impl) {
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self.bump();
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let bounds = self.parse_generic_bounds(Some(self.prev_span))?;
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AliasKind::Existential(bounds)
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} else {
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self.expect(&token::Eq)?;
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let ty = self.parse_ty()?;
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AliasKind::Weak(ty)
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};
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@ -677,6 +677,7 @@ symbols! {
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tuple_indexing,
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Ty,
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ty,
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type_alias_impl_trait,
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TyCtxt,
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TyKind,
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type_alias_enum_variants,
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@ -1,17 +0,0 @@
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// Check that existential types must be ungated to use the `existential` keyword
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existential type Foo: std::fmt::Debug; //~ ERROR existential types are unstable
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trait Bar {
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type Baa: std::fmt::Debug;
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fn define() -> Self::Baa;
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}
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impl Bar for () {
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existential type Baa: std::fmt::Debug; //~ ERROR existential types are unstable
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fn define() -> Self::Baa { 0 }
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}
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fn define() -> Foo { 0 }
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fn main() {}
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@ -1,21 +0,0 @@
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error[E0658]: existential types are unstable
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--> $DIR/feature-gate-existential-type.rs:3:1
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LL | existential type Foo: std::fmt::Debug;
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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= note: for more information, see https://github.com/rust-lang/rust/issues/63063
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= help: add `#![feature(existential_type)]` to the crate attributes to enable
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error[E0658]: existential types are unstable
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--> $DIR/feature-gate-existential-type.rs:11:5
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LL | existential type Baa: std::fmt::Debug;
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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= note: for more information, see https://github.com/rust-lang/rust/issues/63063
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= help: add `#![feature(existential_type)]` to the crate attributes to enable
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0658`.
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@ -0,0 +1,15 @@
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type Foo = impl std::fmt::Debug; //~ ERROR existential types are unstable
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trait Bar {
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type Baa: std::fmt::Debug;
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fn define() -> Self::Baa;
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}
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impl Bar for () {
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type Baa = impl std::fmt::Debug; //~ ERROR existential types are unstable
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fn define() -> Self::Baa { 0 }
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}
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fn define() -> Foo { 0 }
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fn main() {}
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@ -0,0 +1,21 @@
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error[E0658]: existential types are unstable
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--> $DIR/feature-gate-type_alias_impl_trait.rs:1:1
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LL | type Foo = impl std::fmt::Debug;
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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= note: for more information, see https://github.com/rust-lang/rust/issues/63063
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= help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
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error[E0658]: existential types are unstable
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--> $DIR/feature-gate-type_alias_impl_trait.rs:9:5
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LL | type Baa = impl std::fmt::Debug;
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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= note: for more information, see https://github.com/rust-lang/rust/issues/63063
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= help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0658`.
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