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// Test a case where you have an impl of `Foo<X>` for all `X` that
// is being applied to `for<'a> Foo<&'a mut X>`. Issue #19730.
trait Foo<X> {
fn foo(&self, x: X) { }
}
fn want_hrtb<T>()
where T : for<'a> Foo<&'a isize>
{
}
// AnyInt implements Foo<&'a isize> for any 'a, so it is a match.
struct AnyInt;
impl<'a> Foo<&'a isize> for AnyInt { }
fn give_any() {
want_hrtb::<AnyInt>()
}
// StaticInt only implements Foo<&'static isize>, so it is an error.
struct StaticInt;
impl Foo<&'static isize> for StaticInt { }
fn give_static() {
want_hrtb::<StaticInt>() //~ ERROR
}
// &'a u32 only implements Foo<&'a isize> for specific 'a, so it is an error.
impl<'a> Foo<&'a isize> for &'a u32 { }
fn give_some<'a>() {
want_hrtb::<&'a u32>()
//~^ ERROR lifetime may not live long enough
//~| ERROR implementation of `Foo` is not general enough
}
fn main() { }
|
