gcc/testsuite/g++.dg/cpp2a/concepts-placeholder8.C

// { dg-do compile { target c++20 } }

template <class T> concept is_const = __is_same(T, const T);

void f() {
  int x[] = {1,2};
  const int y[] = {3};
  const is_const auto [a,b] = x; // { dg-error "constraints" }
  const is_const auto [c] = y;
}