https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87704
--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> --- Author: redi Date: Thu Oct 25 16:41:54 2018 New Revision: 265499 URL: https://gcc.gnu.org/viewcvs?rev=265499&root=gcc&view=rev Log: PR libstdc++/87704 fix unique_ptr(nullptr_t) constructors Using a delegating constructor to implement these constructors means that they instantiate the destructor, which requires the element_type to be complete. In C++11 and C++14 they were specified to be delegating, but that was changed as part of LWG 2801 so in C++17 they don't require a complete type (as was intended all along). Backport from mainline 2018-10-23 Jonathan Wakely <jwak...@redhat.com> PR libstdc++/87704 * include/bits/unique_ptr.h (unique_ptr::unique_ptr(nullptr_t)): Do not delegate to default constructor. (unique_ptr<T[], D>::unique_ptr(nullptr_t)): Likewise. * testsuite/20_util/unique_ptr/cons/incomplete.cc: New test. Added: branches/gcc-6-branch/libstdc++-v3/testsuite/20_util/unique_ptr/cons/incomplete.cc Modified: branches/gcc-6-branch/libstdc++-v3/ChangeLog branches/gcc-6-branch/libstdc++-v3/include/bits/unique_ptr.h branches/gcc-6-branch/libstdc++-v3/testsuite/20_util/unique_ptr/assign/48635_neg.cc branches/gcc-6-branch/libstdc++-v3/testsuite/20_util/unique_ptr/cons/cv_qual_neg.cc
