[rustc.git] / src / test / ui / impl-trait / negative-reasoning.rs

// Tests that we cannot assume that an opaque type does *not* implement some
// other trait
// revisions: min_tait full_tait
#![feature(min_type_alias_impl_trait)]
#![cfg_attr(full_tait, feature(type_alias_impl_trait))]
//[full_tait]~^ WARN incomplete

trait OpaqueTrait {}
impl<T> OpaqueTrait for T {}
type OpaqueType = impl OpaqueTrait;
fn mk_opaque() -> OpaqueType {
    ()
}

#[derive(Debug)]
struct D<T>(T);

trait AnotherTrait {}
impl<T: std::fmt::Debug> AnotherTrait for T {}

// This is in error, because we cannot assume that `OpaqueType: !Debug`
impl AnotherTrait for D<OpaqueType> {
    //~^ ERROR conflicting implementations of trait `AnotherTrait` for type `D<impl OpaqueTrait>`
}

fn main() {}
Commit	Line	Data
e74abb32 XL	1	// Tests that we cannot assume that an opaque type does not implement some
e74abb32 XL	2	// other trait
6a06907d XL	3	// revisions: min_tait full_tait
	4	#![feature(min_type_alias_impl_trait)]
	5	#![cfg_attr(full_tait, feature(type_alias_impl_trait))]
	6	//[full_tait]~^ WARN incomplete
e74abb32	7
f035d41b XL	8	trait OpaqueTrait {}
f035d41b XL	9	impl<T> OpaqueTrait for T {}
e74abb32	10	type OpaqueType = impl OpaqueTrait;
f035d41b XL	11	fn mk_opaque() -> OpaqueType {
	12	()
	13	}
e74abb32 XL	14
	15	#[derive(Debug)]
	16	struct D<T>(T);
	17
f035d41b XL	18	trait AnotherTrait {}
f035d41b XL	19	impl<T: std::fmt::Debug> AnotherTrait for T {}
e74abb32 XL	20
	21	// This is in error, because we cannot assume that `OpaqueType: !Debug`
	22	impl AnotherTrait for D<OpaqueType> {
f035d41b	23	//~^ ERROR conflicting implementations of trait `AnotherTrait` for type `D<impl OpaqueTrait>`
e74abb32 XL	24	}
	25
	26	fn main() {}