PR libstdc++/83395 fix invocable traits for INVOKE<cv void>

Message ID 20171212174407.GA26640@redhat.com
State New
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Series
  • PR libstdc++/83395 fix invocable traits for INVOKE<cv void>
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Commit Message

Jonathan Wakely Dec. 12, 2017, 5:44 p.m.
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 <jwakely@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.

Patch

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);