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…pecialization, r=oli-obk Allow specializing on const trait bounds
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31 changes: 31 additions & 0 deletions
31
src/test/ui/rfc-2632-const-trait-impl/specializing-constness-2.rs
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#![feature(const_trait_impl, min_specialization, rustc_attrs)] | ||
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#[rustc_specialization_trait] | ||
#[const_trait] | ||
pub trait Sup {} | ||
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impl const Sup for () {} | ||
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#[const_trait] | ||
pub trait A { | ||
fn a() -> u32; | ||
} | ||
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impl<T: Default> A for T { | ||
default fn a() -> u32 { | ||
2 | ||
} | ||
} | ||
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impl<T: Default + ~const Sup> const A for T { | ||
fn a() -> u32 { | ||
3 | ||
} | ||
} | ||
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const fn generic<T: Default>() { | ||
<T as A>::a(); | ||
//~^ ERROR: the trait bound `T: ~const Sup` is not satisfied | ||
} | ||
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fn main() {} |
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src/test/ui/rfc-2632-const-trait-impl/specializing-constness-2.stderr
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error[E0277]: the trait bound `T: ~const Sup` is not satisfied | ||
--> $DIR/specializing-constness-2.rs:27:5 | ||
| | ||
LL | <T as A>::a(); | ||
| ^^^^^^^^^^^^^ the trait `~const Sup` is not implemented for `T` | ||
| | ||
note: required for `T` to implement `~const A` | ||
--> $DIR/specializing-constness-2.rs:20:37 | ||
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LL | impl<T: Default + ~const Sup> const A for T { | ||
| ^ ^ | ||
help: consider further restricting this bound | ||
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LL | const fn generic<T: Default + ~const Sup>() { | ||
| ++++++++++++ | ||
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error: aborting due to previous error | ||
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For more information about this error, try `rustc --explain E0277`. |
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src/test/ui/rfc-2632-const-trait-impl/specializing-constness.rs
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#![feature(const_trait_impl, min_specialization, rustc_attrs)] | ||
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#[rustc_specialization_trait] | ||
#[const_trait] | ||
pub trait Sup {} | ||
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impl const Sup for () {} | ||
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#[const_trait] | ||
pub trait A { | ||
fn a() -> u32; | ||
} | ||
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impl<T: ~const Default> const A for T { | ||
default fn a() -> u32 { | ||
2 | ||
} | ||
} | ||
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impl<T: Default + Sup> A for T { //~ ERROR: cannot specialize | ||
fn a() -> u32 { | ||
3 | ||
} | ||
} | ||
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fn main() {} |
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8
src/test/ui/rfc-2632-const-trait-impl/specializing-constness.stderr
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error: cannot specialize on trait `Default` | ||
--> $DIR/specializing-constness.rs:20:9 | ||
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LL | impl<T: Default + Sup> A for T { | ||
| ^^^^^^^ | ||
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error: aborting due to previous error | ||
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// check-pass | ||
#![feature(const_trait_impl, min_specialization, rustc_attrs)] | ||
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#[rustc_specialization_trait] | ||
#[const_trait] | ||
pub unsafe trait Sup { | ||
fn foo() -> u32; | ||
} | ||
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#[rustc_specialization_trait] | ||
#[const_trait] | ||
pub unsafe trait Sub: ~const Sup {} | ||
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unsafe impl const Sup for u8 { | ||
default fn foo() -> u32 { | ||
1 | ||
} | ||
} | ||
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unsafe impl const Sup for () { | ||
fn foo() -> u32 { | ||
42 | ||
} | ||
} | ||
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unsafe impl const Sub for () {} | ||
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#[const_trait] | ||
pub trait A { | ||
fn a() -> u32; | ||
} | ||
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impl<T: ~const Default> const A for T { | ||
default fn a() -> u32 { | ||
2 | ||
} | ||
} | ||
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impl<T: ~const Default + ~const Sup> const A for T { | ||
default fn a() -> u32 { | ||
3 | ||
} | ||
} | ||
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impl<T: ~const Default + ~const Sub> const A for T { | ||
fn a() -> u32 { | ||
T::foo() | ||
} | ||
} | ||
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const _: () = assert!(<()>::a() == 42); | ||
const _: () = assert!(<u8>::a() == 3); | ||
const _: () = assert!(<u16>::a() == 2); | ||
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fn main() {} |