rust/tests/ui/const-generics/occurs-check/unused-substs-2.rs

30 lines
704 B
Rust

#![feature(generic_const_exprs)]
#![allow(incomplete_features)]
// The goal is to get an unevaluated const `ct` with a `Ty::Infer(TyVar(?1t)` subst.
//
// If we are then able to infer `ty::Infer(TyVar(?1t) := Ty<ct>` we introduced an
// artificial inference cycle.
struct Foo<const N: usize>;
trait Bind<T> {
fn bind() -> (T, Self);
}
// `N` has to be `ConstKind::Unevaluated`.
impl<T> Bind<T> for Foo<{ 6 + 1 }> {
fn bind() -> (T, Self) {
(panic!(), Foo)
}
}
fn main() {
let (mut t, foo) = Foo::bind();
//~^ ERROR mismatched types
//~| NOTE cyclic type
// `t` is `ty::Infer(TyVar(?1t))`
// `foo` contains `ty::Infer(TyVar(?1t))` in its substs
t = foo;
}