Add regression test for #105821

Signed-off-by: Yuki Okushi <[email protected]>

tests/ui/const-generics/issues/issue-105821.rs

@@ -0,0 +1,23 @@
+// check-pass
+
+#![allow(incomplete_features)]
+#![feature(adt_const_params, const_ptr_read, generic_const_exprs)]
+#![allow(dead_code)]
+
+const fn catone<const M: usize>(_a: &[u8; M]) -> [u8; M + 1]
+where
+    [(); M + 1]:,
+{
+    unimplemented!()
+}
+
+struct Catter<const A: &'static [u8]>;
+impl<const A: &'static [u8]> Catter<A>
+where
+    [(); A.len() + 1]:,
+{
+    const ZEROS: &'static [u8; A.len()] = &[0_u8; A.len()];
+    const R: &'static [u8] = &catone(Self::ZEROS);
+}
+
+fn main() {}