r270968 - in /branches/gcc-8-branch/libstdc++-v...

[redi@gcc.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  <jwakely@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