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// Check testing of equality constraints in a higher-ranked context.
pub trait TheTrait<T> {
type A;
fn get(&self, t: T) -> Self::A;
}
struct IntStruct {
x: isize,
}
impl<'a> TheTrait<&'a isize> for IntStruct {
type A = &'a isize;
fn get(&self, t: &'a isize) -> &'a isize {
t
}
}
struct UintStruct {
x: isize,
}
impl<'a> TheTrait<&'a isize> for UintStruct {
type A = &'a usize;
fn get(&self, t: &'a isize) -> &'a usize {
panic!()
}
}
struct Tuple {}
impl<'a> TheTrait<(&'a isize, &'a isize)> for Tuple {
type A = &'a isize;
fn get(&self, t: (&'a isize, &'a isize)) -> &'a isize {
t.0
}
}
fn foo<T>()
where
T: for<'x> TheTrait<&'x isize, A = &'x isize>,
{
// ok for IntStruct, but not UintStruct
}
fn bar<T>()
where
T: for<'x> TheTrait<&'x isize, A = &'x usize>,
{
// ok for UintStruct, but not IntStruct
}
fn tuple_one<T>()
where
T: for<'x, 'y> TheTrait<(&'x isize, &'y isize), A = &'x isize>,
{
// not ok for tuple, two lifetimes and we pick first
}
fn tuple_two<T>()
where
T: for<'x, 'y> TheTrait<(&'x isize, &'y isize), A = &'y isize>,
{
// not ok for tuple, two lifetimes and we pick second
}
fn tuple_three<T>()
where
T: for<'x> TheTrait<(&'x isize, &'x isize), A = &'x isize>,
{
// ok for tuple
}
fn tuple_four<T>()
where
T: for<'x, 'y> TheTrait<(&'x isize, &'y isize)>,
{
// not ok for tuple, two lifetimes, and lifetime matching is invariant
}
pub fn call_foo() {
foo::<IntStruct>();
foo::<UintStruct>(); //~ ERROR type mismatch
}
pub fn call_bar() {
bar::<IntStruct>(); //~ ERROR type mismatch
bar::<UintStruct>();
}
pub fn call_tuple_one() {
tuple_one::<Tuple>();
}
pub fn call_tuple_two() {
tuple_two::<Tuple>();
}
pub fn call_tuple_three() {
tuple_three::<Tuple>();
}
pub fn call_tuple_four() {
tuple_four::<Tuple>();
}
fn main() {}
|
