add regression test for #73730

Author: lcnr

Diff for: src/test/ui/const-generics/type-dependent/issue-73730.rs

@@ -0,0 +1,17 @@
+// check-pass
+#![feature(const_generics)]
+#![allow(incomplete_features)]
+
+trait Foo<'a, A>: Iterator<Item=A> {
+    fn bar<const N: usize>(&mut self) -> *const [A; N];
+}
+
+impl<'a, A, I: ?Sized> Foo<'a, A> for I where I: Iterator<Item=A>  {
+    fn bar<const N: usize>(&mut self) -> *const [A; N] {
+        std::ptr::null()
+    }
+}
+
+fn main() {
+    (0_u8 .. 10).bar::<10_usize>();
+}