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//! This test checks that we allow subtyping predicates that contain opaque types.
//! No hidden types are being constrained in the subtyping predicate, but type and
//! lifetime variables get subtyped in the generic parameter list of the opaque.
//@ check-pass
fn foo() -> impl Default + Copy {
if false {
let x = Default::default();
// add `Subtype(?x, ?y)` obligation
let y = x;
// Make a tuple `(?x, ?y)` and equate it with `(impl Default, u32)`.
// For us to try and prove a `Subtype(impl Default, u32)` obligation,
// we have to instantiate both `?x` and `?y` without any
// `select_where_possible` calls inbetween.
let mut tup = &mut (x, y);
let assign_tup = &mut (foo(), 1u32);
tup = assign_tup;
}
1u32
}
fn main() {}
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