https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89102
--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> --- Author: redi Date: Tue May 7 15:46:44 2019 New Revision: 270968 URL: https://gcc.gnu.org/viewcvs?rev=270968&root=gcc&view=rev Log: PR libstdc++/89102 fix common_type<> and common_type<T> specializations This is a partial implementation of the revised std::common_type rules from P0435R1. Backport from mainline 2019-02-06 Jonathan Wakely <jwak...@redhat.com> PR libstdc++/89102 (partial) * include/std/type_traits (common_type<>): Define. (common_type<T>): Derive from common_type<T, T>. * testsuite/20_util/common_type/requirements/explicit_instantiation.cc: Test zero-length template argument list. * testsuite/20_util/common_type/requirements/sfinae_friendly_1.cc: Test additional single argument cases. * testsuite/20_util/common_type/requirements/sfinae_friendly_2.cc: Adjust expected error. Modified: branches/gcc-8-branch/libstdc++-v3/ChangeLog branches/gcc-8-branch/libstdc++-v3/include/std/type_traits branches/gcc-8-branch/libstdc++-v3/testsuite/20_util/common_type/requirements/explicit_instantiation.cc branches/gcc-8-branch/libstdc++-v3/testsuite/20_util/common_type/requirements/sfinae_friendly_1.cc branches/gcc-8-branch/libstdc++-v3/testsuite/20_util/common_type/requirements/sfinae_friendly_2.cc
