1 files changed, 33 insertions, 0 deletions
diff --git a/src/test/ui/const-generics/invariant.rs b/src/test/ui/const-generics/invariant.rs
new file mode 100644
index 000000000..ee191b65c
--- /dev/null
+++ b/src/test/ui/const-generics/invariant.rs
@@ -0,0 +1,33 @@
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+use std::marker::PhantomData;
+
+trait SadBee {
+    const ASSOC: usize;
+}
+// fn(&'static ())` is a supertype of `for<'a> fn(&'a ())` while
+// we allow two different impls for these types, leading
+// to different const eval results.
+impl SadBee for for<'a> fn(&'a ()) {
+    const ASSOC: usize = 0;
+}
+impl SadBee for fn(&'static ()) {
+    //~^ WARNING conflicting implementations of trait
+    //~| WARNING this was previously accepted
+    const ASSOC: usize = 100;
+}
+
+struct Foo<T: SadBee>([u8; <T as SadBee>::ASSOC], PhantomData<T>)
+where
+    [(); <T as SadBee>::ASSOC]: ;
+
+fn covariant(
+    v: &'static Foo<for<'a> fn(&'a ())>
+) -> &'static Foo<fn(&'static ())> {
+    v //~ ERROR mismatched types
+}
+
+fn main() {
+    let y = covariant(&Foo([], PhantomData));
+    println!("{:?}", y.0);
+}