gcc can't find base class object

The following code doesn't compile with gcc, but it compiles with clang.

struct Base {
  void base() {}
};

template< typename T >
struct Foo : Base {

  struct Bar : Base {
  };

  struct Baz : Bar {
    void f() {
      base();
    }
  };
};

int main() {
  Foo<int>::Baz{}.f();
}

gcc spits the following error:

13:11: error: cannot call member function 'void Base::base()' without object
   13 |       base();
      |       ~~~~^~

Interestingly, if I change it to this->base(); or Base::base();, then it compiles.

Why can't gcc find the Base class object? Baz is clearly a subclass of Base.