add folly::void_t like C++17's std::void_t
authorEric Niebler <eniebler@fb.com>
Sat, 7 Jan 2017 02:32:01 +0000 (18:32 -0800)
committerFacebook Github Bot <facebook-github-bot@users.noreply.github.com>
Sat, 7 Jan 2017 02:32:51 +0000 (18:32 -0800)
commite39748150f912c52987d65a6636f75506c873e35
tree598435a526d18b9dd133a9164fb64fb2957c6d1a
parentc5e6d87b2adc858072885ec321968c973372a7ec
add folly::void_t like C++17's std::void_t

Summary:
C++17 is adding std::void_t. It's handy for controlling class template partial specialization. Folly should have it too.

See http://en.cppreference.com/w/cpp/types/void_t

Reviewed By: yfeldblum

Differential Revision: D4387302

fbshipit-source-id: 85f955f3d8cfacbd6c9e61fb3f5cf53c056459bb
folly/Traits.h
folly/test/TraitsTest.cpp