Add regression test for #65675

Author: varkor

src/test/ui/const-generics/issues/issue-65675.rs

@@ -0,0 +1,10 @@
+// run-pass
+// compile-flags: -Z chalk
+
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+pub struct Foo<T, const N: usize>([T; N]);
+impl<T, const N: usize> Foo<T, {N}> {}
+
+fn main() {}

src/test/ui/const-generics/issues/issue-65675.stderr

@@ -0,0 +1,8 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/issue-65675.rs:4:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+