[Bug libstdc++/83395] [7/8 Regression] is_invocable_r fails for cv-qualified void return type

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83395

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Author: redi
Date: Tue Dec 12 17:42:19 2017
New Revision: 255584

URL: https://gcc.gnu.org/viewcvs?rev=255584&root=gcc&view=rev
Log:
PR libstdc++/83395 fix invocable traits for INVOKE<cv void>

        PR libstdc++/83395
        * include/std/type_traits (__is_invocable_impl): Remove partial
        specialization for INVOKE<void> and restore is_void<R> check in
        primary template.
        (__is_nt_invocable_impl): Likewise.
        * testsuite/20_util/is_invocable/83395.cc: New test.
        * testsuite/20_util/is_nothrow_invocable/83395.cc: New test.

Added:
    trunk/libstdc++-v3/testsuite/20_util/is_invocable/83395.cc
    trunk/libstdc++-v3/testsuite/20_util/is_nothrow_invocable/83395.cc
Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/std/type_traits