This restores the is_void<R> check to __is_invocable_impl that I
removed recently, because otherwise we don't handle cv void correctly
(and restoring the is_void check seemed simpler than adding partial
specializations for 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.
Tested powerpc64le-linux, committed to trunk. Backport to follow for
gcc-7-branch.
commit 0f36841953ac86d12a0dbbf5548da7799b7ac7a6
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Tue Dec 12 17:03:31 2017 +0000
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.
diff --git a/libstdc++-v3/include/std/type_traits
b/libstdc++-v3/include/std/type_traits
index 1d639e452f3..3d94566fa63 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -2589,12 +2589,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Result, typename _Ret>
struct __is_invocable_impl<_Result, _Ret, __void_t<typename _Result::type>>
- : is_convertible<typename _Result::type, _Ret>::type
- { };
-
- template<typename _Result>
- struct __is_invocable_impl<_Result, void, __void_t<typename _Result::type>>
- : true_type
+ : __or_<is_void<_Ret>, is_convertible<typename _Result::type, _Ret>>::type
{ };
template<typename _Fn, typename... _ArgTypes>
@@ -2699,14 +2694,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Result, typename _Ret>
struct __is_nt_invocable_impl<_Result, _Ret,
__void_t<typename _Result::type>>
- : __and_<is_convertible<typename _Result::type, _Ret>,
- is_nothrow_constructible<_Ret, typename _Result::type>>
- { };
-
- template<typename _Result>
- struct __is_nt_invocable_impl<_Result, void,
- __void_t<typename _Result::type>>
- : true_type
+ : __or_<is_void<_Ret>,
+ __and_<is_convertible<typename _Result::type, _Ret>,
+ is_nothrow_constructible<_Ret, typename _Result::type>>>
{ };
/// std::is_nothrow_invocable_r
diff --git a/libstdc++-v3/testsuite/20_util/is_invocable/83395.cc
b/libstdc++-v3/testsuite/20_util/is_invocable/83395.cc
new file mode 100644
index 00000000000..7fb1368cd09
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/is_invocable/83395.cc
@@ -0,0 +1,28 @@
+// Copyright (C) 2017 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+// { dg-do compile { target c++17 } }
+
+#include <type_traits>
+
+// PR libstdc++/83395
+using F = int(*)();
+static_assert(std::is_invocable_r<void, F>::value);
+static_assert(std::is_invocable_r<void const, F>::value);
+static_assert(std::is_invocable_r<void volatile, F>::value);
+static_assert(std::is_invocable_r<void const volatile, F>::value);
diff --git a/libstdc++-v3/testsuite/20_util/is_nothrow_invocable/83395.cc
b/libstdc++-v3/testsuite/20_util/is_nothrow_invocable/83395.cc
new file mode 100644
index 00000000000..2a253df8d1b
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/is_nothrow_invocable/83395.cc
@@ -0,0 +1,28 @@
+// Copyright (C) 2017 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+// { dg-do compile { target c++17 } }
+
+#include <type_traits>
+
+// PR libstdc++/83395
+using F = int(*)() noexcept;
+static_assert(std::is_nothrow_invocable_r<void, F>::value);
+static_assert(std::is_nothrow_invocable_r<void const, F>::value);
+static_assert(std::is_nothrow_invocable_r<void volatile, F>::value);
+static_assert(std::is_nothrow_invocable_r<void const volatile, F>::value);
