Add regression test for rust-lang#73298

Author: varkor

src/test/ui/const-generics/issue-73298.rs

@@ -0,0 +1,24 @@
+// build-pass
+// revisions: full min
+
+#![cfg_attr(full, feature(const_generics))]
+#![cfg_attr(full, allow(incomplete_features))]
+#![cfg_attr(min, feature(min_const_generics))]
+
+use std::convert::AsMut;
+use std::default::Default;
+
+trait Foo: Sized {
+    type Baz: Default + AsMut<[u8]>;
+    fn bar() {
+        Self::Baz::default().as_mut();
+    }
+}
+
+impl Foo for () {
+    type Baz = [u8; 1 * 1];
+}
+
+fn main() {
+    <() as Foo>::bar();
+}