The x86 attributes such as ms_abi, stdcall, fastcall etc. alter the
function type, which means that functions with one of those attributes
do not match any of the partial specializations of std::is_function.
Rather than duplicating the list for every calling convention, this
adds a fallback to the std::is_function primary template which
identifies other function types. The fallback works by assuming that
all function types fall into one of two categories: referenceable and
abominable. The former can be detected by testing for
function-to-pointer decay, and the latter are non-referenceable types
that are not cv void.
In order to detect referenceable types it's necessary to replace the
current definition of __is_referenceable with one that doesn't depend on
std::is_function, to avoid a cycle. The definition of std::decay can
also be modified to only act on referenceable function types, because
abominable function types do not decay.
PR libstdc++/91371
* include/std/type_traits (__declval, declval, __void_t): Declare
earlier in the file.
(__is_referenceable): Rewrite to not depend on is_function.
(__is_referenceable_function): New trait to identify non-abominable
function types.
(__is_qualified_function): New alias to identify abominable function
types.
(is_function): Make primary template use __is_referenceable_function
and __is_qualified_function to detect function types not covered by
the partial specializations.
(__decay_selector): Use __is_referenceable_function instead of
is_function.
(__decay_selector<_Up, false, true>): Do not use add_pointer.
* testsuite/20_util/bind/91371.cc: New test.
* testsuite/20_util/is_function/91371.cc: New test.
* testsuite/20_util/is_function/value.cc: Check more pointer types.
* testsuite/20_util/is_member_function_pointer/91371.cc: New test.
Tested x86_64-linux. Not committed yet.
I'd like to hear Daniel's thoughts on this approach, as he wrote the
original __is_referenceable trait, and much of <type_traits>.
This new __is_referenceable simply uses void_t<T&> to detect whether
forming T& is valid.
The detection for function-to-pointer decay works by checking whether
static_cast<T*>(declval<T&>()) is well-formed. If T is not a class
type (which could have a conversion operator) and is not nullptr or cv
void*cv (which can convert to nullptr* and cv void*cv* repectively)
then it must be a function.
The detection for abominable function types assumes that all types are
referenceable except functions with cv- or ref-qualifiers and cv void
types. So if it's not referenceable and not void, it's an abominable
function type.
commit 2c8c1d0ef4b9ed6e80abf3694618c0e63859de78
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Fri Aug 16 15:03:54 2019 +0100
PR libstdc++/91371 make std::is_function handle other calling conventions
The x86 attributes such as ms_abi, stdcall, fastcall etc. alter the
function type, which means that functions with one of those attributes
do not match any of the partial specializations of std::is_function.
Rather than duplicating the list for every calling convention, add a
fallback to the std::is_function primary template which identifies other
function types. The fallback works by assuming that all function types
fall into one of two categories: referenceable and abominable. The
former can be detected by testing for function-to-pointer decay, and the
latter are non-referenceable types that are not cv void.
In order to detect referenceable types it's necessary to replace the
current definition of __is_referenceable with one that doesn't depend on
std::is_function, to avoid a cycle. The definition of std::decay can
also be modified to only act on referenceable function types, because
abominable function types do not decay.
PR libstdc++/91371
* include/std/type_traits (__declval, declval, __void_t): Declare
earlier in the file.
(__is_referenceable): Rewrite to not depend on is_function.
(__is_referenceable_function): New trait to identify non-abominable
function types.
(__is_qualified_function): New alias to identify abominable function
types.
(is_function): Make primary template use __is_referenceable_function
and __is_qualified_function to detect function types not covered by
the partial specializations.
(__decay_selector): Use __is_referenceable_function instead of
is_function.
(__decay_selector<_Up, false, true>): Do not use add_pointer.
* testsuite/20_util/bind/91371.cc: New test.
* testsuite/20_util/is_function/91371.cc: New test.
* testsuite/20_util/is_function/value.cc: Check more pointer types.
* testsuite/20_util/is_member_function_pointer/91371.cc: New test.
diff --git a/libstdc++-v3/include/std/type_traits
b/libstdc++-v3/include/std/type_traits
index 44db2cade5d..ca16cb7ccc1 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -480,10 +480,64 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
: public integral_constant<bool, __is_class(_Tp)>
{ };
+ template<typename _Tp, typename _Up = _Tp&&>
+ _Up
+ __declval(int);
+
+ template<typename _Tp>
+ _Tp
+ __declval(long);
+
+ /**
+ * @brief Utility to simplify expressions used in unevaluated operands
+ * @ingroup utilities
+ */
+ template<typename _Tp>
+ auto declval() noexcept -> decltype(__declval<_Tp>(0));
+
+ // __void_t (std::void_t for C++11)
+ template<typename...> using __void_t = void;
+
+ template<typename _Tp> struct is_null_pointer;
+
+ // Utility to detect referenceable types ([defns.referenceable]).
+ template<typename _Tp, typename = void>
+ struct __is_referenceable
+ : false_type { };
+
+ template<typename _Tp>
+ struct __is_referenceable<_Tp, __void_t<_Tp&>>
+ : true_type { };
+
+ // A function type that does not have cv-qualifiers or a ref-qualifier.
+ template<typename _Tp,
+ bool = __is_class(_Tp) || __is_union(_Tp),
+ typename = void>
+ struct __is_referenceable_function
+ : false_type { };
+
+ template<typename _Tp>
+ struct __is_referenceable_function<_Tp, false,
+ __void_t<decltype(static_cast<_Tp*>(std::declval<_Tp&>()))>>
+ : __not_<__or_<is_pointer<_Tp>, is_null_pointer<_Tp>>>::type { };
+
+ // A function type with cv-qualifiers and/or a ref-qualifier.
+ // This assumes that only types that are not referenceable are cv void types
+ // and qualified function types.
+ template<typename _Tp>
+ using __is_qualified_function
+ = __not_<__or_<__is_referenceable<_Tp>, is_void<_Tp>>>;
+
/// is_function
- template<typename>
+ template<typename _Tp>
struct is_function
- : public false_type { };
+ : __or_<__is_referenceable_function<_Tp>,
+ __is_qualified_function<_Tp>>::type
+ { };
+
+ // Define partial specializations for most function types.
+ // The primary template is used for function types with alternative
+ // calling conventions (such as x86 stdcall) and for non-function types.
template<typename _Res, typename... _ArgTypes _GLIBCXX_NOEXCEPT_PARM>
struct is_function<_Res(_ArgTypes...) _GLIBCXX_NOEXCEPT_QUAL>
@@ -705,24 +759,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#endif
>;
-
- // Utility to detect referenceable types ([defns.referenceable]).
-
- template<typename _Tp>
- struct __is_referenceable
- : public __or_<is_object<_Tp>, is_reference<_Tp>>::type
- { };
-
- template<typename _Res, typename... _Args _GLIBCXX_NOEXCEPT_PARM>
- struct __is_referenceable<_Res(_Args...) _GLIBCXX_NOEXCEPT_QUAL>
- : public true_type
- { };
-
- template<typename _Res, typename... _Args _GLIBCXX_NOEXCEPT_PARM>
- struct __is_referenceable<_Res(_Args......) _GLIBCXX_NOEXCEPT_QUAL>
- : public true_type
- { };
-
// Type properties.
/// is_const
@@ -841,22 +877,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// Destructible and constructible type properties.
- /**
- * @brief Utility to simplify expressions used in unevaluated operands
- * @ingroup utilities
- */
-
- template<typename _Tp, typename _Up = _Tp&&>
- _Up
- __declval(int);
-
- template<typename _Tp>
- _Tp
- __declval(long);
-
- template<typename _Tp>
- auto declval() noexcept -> decltype(__declval<_Tp>(0));
-
template<typename, unsigned = 0>
struct extent;
@@ -2186,7 +2206,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// in make_pair, make_tuple, etc.
template<typename _Up,
bool _IsArray = is_array<_Up>::value,
- bool _IsFunction = is_function<_Up>::value>
+ bool _IsFunction = __is_referenceable_function<_Up>::value>
struct __decay_selector;
// NB: DR 705.
@@ -2200,7 +2220,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Up>
struct __decay_selector<_Up, false, true>
- { typedef typename add_pointer<_Up>::type __type; };
+ { typedef _Up* __type; };
/// decay
template<typename _Tp>
@@ -2261,9 +2281,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
struct conditional<false, _Iftrue, _Iffalse>
{ typedef _Iffalse type; };
- // __void_t (std::void_t for C++11)
- template<typename...> using __void_t = void;
-
/// common_type
template<typename... _Tp>
struct common_type;
diff --git a/libstdc++-v3/testsuite/20_util/bind/91371.cc
b/libstdc++-v3/testsuite/20_util/bind/91371.cc
new file mode 100644
index 00000000000..1c6f55e9ece
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/bind/91371.cc
@@ -0,0 +1,37 @@
+// Copyright (C) 2019 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-do compile { target i?86-*-* x86_64-*-* } }
+// { dg-require-effective-target c++11 }
+
+#include <functional>
+
+int bar(int) __attribute__((ms_abi));
+int baz(int) __attribute__((sysv_abi));
+
+void
+test01()
+{
+ // PR libstdc++/91371
+ std::bind(bar, 5)();
+ std::bind(baz, 5)();
+
+ static_assert(std::is_function<decltype(bar)>::value, "");
+ static_assert(std::is_function<decltype(baz)>::value, "");
+ static_assert(std::is_pointer<std::decay_t<decltype(bar)>>::value, "");
+ static_assert(std::is_pointer<std::decay_t<decltype(baz)>>::value, "");
+}
diff --git a/libstdc++-v3/testsuite/20_util/is_function/91371.cc
b/libstdc++-v3/testsuite/20_util/is_function/91371.cc
new file mode 100644
index 00000000000..c51d373027b
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/is_function/91371.cc
@@ -0,0 +1,47 @@
+// Copyright (C) 2019 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-do compile { target i?86-*-* x86_64-*-* } }
+// { dg-require-effective-target c++11 }
+
+#include <type_traits>
+
+using std::is_function;
+
+#ifdef __i386__
+static_assert(is_function<void __attribute__((thiscall)) ()>::value, "");
+static_assert(is_function<void __attribute__((thiscall)) () const>::value, "");
+static_assert(is_function<void __attribute__((fastcall)) ()>::value, "");
+static_assert(is_function<void __attribute__((fastcall)) () const>::value, "");
+static_assert(is_function<void __attribute__((stdcall)) ()>::value, "");
+static_assert(is_function<void __attribute__((stdcall)) () const>::value, "");
+#endif
+static_assert(is_function<void __attribute__((ms_abi)) ()>::value, "");
+static_assert(is_function<void __attribute__((ms_abi)) () const>::value, "");
+static_assert(is_function<void __attribute__((ms_abi)) () const &>::value, "");
+static_assert(is_function<void __attribute__((ms_abi)) () &&>::value, "");
+static_assert(is_function<void __attribute__((sysv_abi)) ()>::value, "");
+static_assert(is_function<void __attribute__((sysv_abi)) () const>::value, "");
+
+struct X { operator X*(); };
+static_assert(!is_function<X>::value, "");
+static_assert(!is_function<X&>::value, "");
+static_assert(!is_function<X*>::value, "");
+union Y { operator Y*(); int i; long l;};
+static_assert(!is_function<Y>::value, "");
+static_assert(!is_function<Y&>::value, "");
+static_assert(!is_function<Y*>::value, "");
diff --git a/libstdc++-v3/testsuite/20_util/is_function/value.cc
b/libstdc++-v3/testsuite/20_util/is_function/value.cc
index 7b94b58b6cb..4a3bb7c5740 100644
--- a/libstdc++-v3/testsuite/20_util/is_function/value.cc
+++ b/libstdc++-v3/testsuite/20_util/is_function/value.cc
@@ -37,12 +37,18 @@ void test01()
char (int, ClassType) const volatile &&>(true), "");
// Negative tests.
+ static_assert(test_category<is_function, int*>(false), "");
static_assert(test_category<is_function, int&>(false), "");
static_assert(test_category<is_function, void>(false), "");
static_assert(test_category<is_function, const void>(false), "");
+ static_assert(test_category<is_function, void*>(false), "");
+ static_assert(test_category<is_function, const void*>(false), "");
+ static_assert(test_category<is_function, void**>(false), "");
+ static_assert(test_category<is_function, std::nullptr_t>(false), "");
static_assert(test_category<is_function, AbstractClass>(false), "");
static_assert(test_category<is_function, int(&)(int)>(false), "");
+ static_assert(test_category<is_function, int(*)(int)>(false), "");
// Sanity check.
static_assert(test_category<is_function, ClassType>(false), "");
diff --git a/libstdc++-v3/testsuite/20_util/is_member_function_pointer/91371.cc
b/libstdc++-v3/testsuite/20_util/is_member_function_pointer/91371.cc
new file mode 100644
index 00000000000..25fecc11cd8
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/is_member_function_pointer/91371.cc
@@ -0,0 +1,35 @@
+// Copyright (C) 2019 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-do compile { target i?86-*-* x86_64-*-* } }
+// { dg-require-effective-target c++11 }
+
+#include <type_traits>
+
+struct Z
+{
+ void __attribute__((ms_abi)) f() const { }
+ void __attribute__((sysv_abi)) g() const { }
+#ifdef __i386__
+ void __attribute__((thiscall)) h() const { }
+#endif
+};
+static_assert( std::is_member_function_pointer<decltype(&Z::f)>::value, "" );
+static_assert( std::is_member_function_pointer<decltype(&Z::g)>::value, "" );
+#ifdef __i386__
+static_assert( std::is_member_function_pointer<decltype(&Z::h)>::value, "" );
+#endif
