const char * x = "foo";
char const * y = "foo";
char * const z = "foo";
void f() {
  x[1] = 'a';  // Error
  y[1] = 'a';  // Error
  z[1] = 'a';  // Compiles, but may segfault
  x = "bar";
  y = "bar";
  z = "bar";  // Error
}