File: const-default-bound-non-const-specialized-bound.rs

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// Tests that trait bounds on specializing trait impls must be `~const` if the
// same bound is present on the default impl and is `~const` there.

#![feature(const_trait_impl)]
#![feature(rustc_attrs)]
#![feature(min_specialization)]

#[rustc_specialization_trait]
trait Specialize {}

#[const_trait]
trait Foo {}

#[const_trait]
trait Bar {}

// bgr360: I was only able to exercise the code path that raises the
// "missing ~const qualifier" error by making this base impl non-const, even
// though that doesn't really make sense to do. As seen below, if the base impl
// is made const, rustc fails earlier with an overlapping impl failure.
impl<T> Bar for T
where
    T: ~const Foo,
{}

impl<T> Bar for T
where
    T: Foo, //~ ERROR missing `~const` qualifier
    T: Specialize,
{}

#[const_trait]
trait Baz {}

impl<T> const Baz for T
where
    T: ~const Foo,
{}

impl<T> const Baz for T //~ ERROR conflicting implementations of trait `Baz`
where
    T: Foo,
    T: Specialize,
{}

fn main() {}