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Gate const trait syntax #144956

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3 changes: 3 additions & 0 deletions compiler/rustc_parse/src/parser/item.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -885,6 +885,9 @@ impl<'a> Parser<'a> {
/// Parses `unsafe? auto? trait Foo { ... }` or `trait Foo = Bar;`.
fn parse_item_trait(&mut self, attrs: &mut AttrVec, lo: Span) -> PResult<'a, ItemKind> {
let constness = self.parse_constness(Case::Sensitive);
if let Const::Yes(span) = constness {
self.psess.gated_spans.gate(sym::const_trait_impl, span);
}
let safety = self.parse_safety(Case::Sensitive);
// Parse optional `auto` prefix.
let is_auto = if self.eat_keyword(exp!(Auto)) {
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3 changes: 3 additions & 0 deletions tests/ui/traits/const-traits/feature-gate.rs
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Expand Up @@ -13,6 +13,9 @@ impl const T for S {}
const fn f<A: [const] T>() {} //[stock]~ ERROR const trait impls are experimental
fn g<A: const T>() {} //[stock]~ ERROR const trait impls are experimental

const trait Trait {} //[stock]~ ERROR const trait impls are experimental
#[cfg(false)] const trait Trait {} //[stock]~ ERROR const trait impls are experimental

macro_rules! discard { ($ty:ty) => {} }

discard! { impl [const] T } //[stock]~ ERROR const trait impls are experimental
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26 changes: 23 additions & 3 deletions tests/ui/traits/const-traits/feature-gate.stock.stderr
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Expand Up @@ -29,7 +29,27 @@ LL | fn g<A: const T>() {}
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error[E0658]: const trait impls are experimental
--> $DIR/feature-gate.rs:18:17
--> $DIR/feature-gate.rs:16:1
|
LL | const trait Trait {}
| ^^^^^
|
= note: see issue #143874 <https://github.com/rust-lang/rust/issues/143874> for more information
= help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error[E0658]: const trait impls are experimental
--> $DIR/feature-gate.rs:17:15
|
LL | #[cfg(false)] const trait Trait {}
| ^^^^^
|
= note: see issue #143874 <https://github.com/rust-lang/rust/issues/143874> for more information
= help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error[E0658]: const trait impls are experimental
--> $DIR/feature-gate.rs:21:17
|
LL | discard! { impl [const] T }
| ^^^^^^^
Expand All @@ -39,7 +59,7 @@ LL | discard! { impl [const] T }
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error[E0658]: const trait impls are experimental
--> $DIR/feature-gate.rs:19:17
--> $DIR/feature-gate.rs:22:17
|
LL | discard! { impl const T }
| ^^^^^
Expand All @@ -58,6 +78,6 @@ LL | #[const_trait]
= help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error: aborting due to 6 previous errors
error: aborting due to 8 previous errors

For more information about this error, try `rustc --explain E0658`.
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