On 31/05/17 13:45 +0100, Jonathan Wakely wrote:
>vector<bool> does addressof(*ptr) where ptr is returned by
>allocate(n), but if n==0 that pointer might not be dereferencable.
>
>While testing the fix I also found some bugs in the
>__gnu_test::PointerBase helper that needed correcting.
>
>	PR libstdc++/80893
>	* include/bits/stl_bvector.h (vector<bool>::_M_initialize): Avoid
>	null pointer dereference when size is zero.
>	* testsuite/23_containers/vector/bool/80893.cc: New.
>	* testsuite/util/testsuite_allocator.h (PointerBase::PointerBase):
>	Add non-explicit constructor from nullptr.
>	(PointerBase::derived() const): Add const-qualified overload.
>
>Tested powerpc64le-linux, committed to trunk.

The new test fails in C++98 modes, as shown at https://gcc.gnu.org/ml/gcc-testresults/2017-06/msg01833.html

Fixed like so, committed to trunk.