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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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13
src/libsyntax/feature_gate.rs
View file

@ -453,9 +453,6 @@ declare_features! (
// Allows `#[doc(alias = "...")]`.
(active, doc_alias, "1.27.0", Some(50146), None),
// Allows defining `existential type`s.
(active, existential_type, "1.28.0", Some(63063), None),
// Allows inconsistent bounds in where clauses.
(active, trivial_bounds, "1.28.0", Some(48214), None),
@ -560,6 +557,9 @@ declare_features! (
// Allows `[x; N]` where `x` is a constant (RFC 2203).
(active, const_in_array_repeat_expressions, "1.37.0", Some(49147), None),
// Allows `impl Trait` to be used inside type aliases (RFC 2515).
(active, type_alias_impl_trait, "1.38.0", Some(63063), None),
// -------------------------------------------------------------------------
// feature-group-end: actual feature gates
// -------------------------------------------------------------------------
@ -625,6 +625,9 @@ declare_features! (
(removed, dropck_parametricity, "1.38.0", Some(28498), None, None),
(removed, await_macro, "1.38.0", Some(50547), None,
Some("subsumed by `.await` syntax")),
// Allows defining `existential type`s.
(removed, existential_type, "1.38.0", Some(63063), None,
Some("removed in favor of `#![feature(type_alias_impl_trait)]`")),
// -------------------------------------------------------------------------
// feature-group-end: removed features
@ -2017,7 +2020,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
ast::ItemKind::Existential(..) => {
gate_feature_post!(
&self,
existential_type,
type_alias_impl_trait,
i.span,
"existential types are unstable"
);
@ -2246,7 +2249,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
ast::ImplItemKind::Existential(..) => {
gate_feature_post!(
&self,
existential_type,
type_alias_impl_trait,
ii.span,
"existential types are unstable"
);

25
src/libsyntax/parse/parser.rs
View file

@ -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)
};

1
src/libsyntax_pos/symbol.rs
View file

@ -677,6 +677,7 @@ symbols! {
tuple_indexing,
Ty,
ty,
type_alias_impl_trait,
TyCtxt,
TyKind,
type_alias_enum_variants,

17
src/test/ui/feature-gates/feature-gate-existential-type.rs
View file

@ -1,17 +0,0 @@
// Check that existential types must be ungated to use the `existential` keyword
existential type Foo: std::fmt::Debug; //~ ERROR existential types are unstable
trait Bar {
type Baa: std::fmt::Debug;
fn define() -> Self::Baa;
}
impl Bar for () {
existential type Baa: std::fmt::Debug; //~ ERROR existential types are unstable
fn define() -> Self::Baa { 0 }
}
fn define() -> Foo { 0 }
fn main() {}

21
src/test/ui/feature-gates/feature-gate-existential-type.stderr
View file

@ -1,21 +0,0 @@
error[E0658]: existential types are unstable
--> $DIR/feature-gate-existential-type.rs:3:1
|
LL | existential type Foo: std::fmt::Debug;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: for more information, see https://github.com/rust-lang/rust/issues/63063
= help: add `#![feature(existential_type)]` to the crate attributes to enable
error[E0658]: existential types are unstable
--> $DIR/feature-gate-existential-type.rs:11:5
|
LL | existential type Baa: std::fmt::Debug;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: for more information, see https://github.com/rust-lang/rust/issues/63063
= help: add `#![feature(existential_type)]` to the crate attributes to enable
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0658`.

15
src/test/ui/feature-gates/feature-gate-type_alias_impl_trait.rs Normal file
View file

@ -0,0 +1,15 @@
type Foo = impl std::fmt::Debug; //~ ERROR existential types are unstable
trait Bar {
type Baa: std::fmt::Debug;
fn define() -> Self::Baa;
}
impl Bar for () {
type Baa = impl std::fmt::Debug; //~ ERROR existential types are unstable
fn define() -> Self::Baa { 0 }
}
fn define() -> Foo { 0 }
fn main() {}

21
src/test/ui/feature-gates/feature-gate-type_alias_impl_trait.stderr Normal file
View file

@ -0,0 +1,21 @@
error[E0658]: existential types are unstable
--> $DIR/feature-gate-type_alias_impl_trait.rs:1:1
|
LL | type Foo = impl std::fmt::Debug;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: for more information, see https://github.com/rust-lang/rust/issues/63063
= help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
error[E0658]: existential types are unstable
--> $DIR/feature-gate-type_alias_impl_trait.rs:9:5
|
LL | type Baa = impl std::fmt::Debug;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: for more information, see https://github.com/rust-lang/rust/issues/63063
= help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0658`.