add testcase for rust-lang#79152

Author: matthiaskrgr

src/test/ui/const_fn_vec_mutation_79152.rs

@@ -0,0 +1,11 @@
+// check-pass
+
+// https://github.com/rust-lang/rust/issues/79152
+const fn foo() {
+    let mut array = [[0; 1]; 1];
+    array[0][0] = 1;
+}
+
+pub fn main() {
+    foo()
+}