Firstly, isn’t that a syntax error? There’s a stray “const” in there. You probably meant

  const int * const hello = &world;

Secondly, what should the compiler complain about? You have a const int, and then a const pointer to const int, pointing to that first const int. What’s the problem?

Thirdly, the latest C version supported by GCC is “-std=c17”.

Nah const is fun

  int main()
  {
    const int world = 42;
    const const const int const const * const const hello = &world;

    return 0;
  }

Is a valid program

https://onlinegdb.com/SJcwJrRzd

Sure, but those extra “const” do not mean anything, and are apparently ignored by the compiler.