Our implementation rejects this well-formed program (derived from the libc++ test that fails because of this bug):

#include <algorithm>
#include <iterator>

struct incomplete;

template <class T>
struct wrapper {
    T t;
};

int main() {
    wrapper<incomplete>* some_pointers[42]{};
    std::sort(std::begin(some_pointers), std::end(some_pointers));
}

by trying to instantiate wrapper<incomplete> despite that such instantiation is not necessary. The unqualified call to _Adl_verify_range(_First, _Last) (which appears in most algorithms, std::sort is simply an exemplar) necessitates instantiation of wrapper<incomplete> when _First has type wrapper<incomplete>**.

The problem runs deeper than simply _STD-qualifying _Adl_verify_range:

• the machinery it uses presumably makes other unqualified calls that will need to be dealt with, and
• the unqualified call to _Verify_range should be avoided when the arguments are pointers.