Currently we only constrain std::function's constructor to reject
integral arguments, this patch changes it to reject non-callable
arguments. This is the proposed resolution of LWG 2132, I had already
planned to do this anyway before the issue was opened so I don't see
any need to wait for a DR.
* include/std/functional (function::function(F)): LWG 2132: Disable
constructor if argument isn't callable.
* testsuite/20_util/function/cons/callable.cc: New.
Tested x86_64-linux, committed to trunk.
commit 0e069c4221d6ed4fda7d10938470c472170dcad7
Author: Jonathan Wakely <jwakely....@gmail.com>
Date: Tue Feb 14 22:22:48 2012 +0000
* include/std/functional (function::function(F)): LWG 2132: Disable
constructor if argument isn't callable.
* testsuite/20_util/function/cons/callable.cc: New.
diff --git a/libstdc++-v3/include/std/functional
b/libstdc++-v3/include/std/functional
index 980c6ab..0edb4f1 100644
--- a/libstdc++-v3/include/std/functional
+++ b/libstdc++-v3/include/std/functional
@@ -1856,7 +1856,7 @@ _GLIBCXX_HAS_NESTED_TYPE(result_type)
{
typedef _Function_base::_Base_manager<_Functor*> _Base;
- public:
+ public:
static bool
_M_manager(_Any_data& __dest, const _Any_data& __source,
_Manager_operation __op)
@@ -1994,7 +1994,7 @@ _GLIBCXX_HAS_NESTED_TYPE(result_type)
typedef _Simple_type_wrapper<_Functor> _Wrapper;
typedef _Function_base::_Base_manager<_Wrapper> _Base;
- public:
+ public:
static bool
_M_manager(_Any_data& __dest, const _Any_data& __source,
_Manager_operation __op)
@@ -2038,7 +2038,23 @@ _GLIBCXX_HAS_NESTED_TYPE(result_type)
{
typedef _Res _Signature_type(_ArgTypes...);
- struct _Useless { };
+ template<typename _Functor>
+ using _Invoke = decltype(__callable_functor(std::declval<_Functor&>())
+ (std::declval<_ArgTypes>()...) );
+
+ template<typename _CallRes, typename _Res1>
+ struct _CheckResult
+ : is_convertible<_CallRes, _Res1> { };
+
+ template<typename _CallRes>
+ struct _CheckResult<_CallRes, void>
+ : true_type { };
+
+ template<typename _Functor>
+ using _Callable = _CheckResult<_Invoke<_Functor>, _Res>;
+
+ template<typename _Cond, typename _Tp>
+ using _Requires = typename enable_if<_Cond::value, _Tp>::type;
public:
typedef _Res result_type;
@@ -2099,11 +2115,9 @@ _GLIBCXX_HAS_NESTED_TYPE(result_type)
* If @a __f is a non-NULL function pointer or an object of type @c
* reference_wrapper<F>, this function will not throw.
*/
- template<typename _Functor>
- function(_Functor __f,
- typename enable_if<
- !is_integral<_Functor>::value, _Useless>::type
- = _Useless());
+ template<typename _Functor,
+ typename = _Requires<_Callable<_Functor>, void>>
+ function(_Functor);
/**
* @brief %Function assignment operator.
@@ -2178,7 +2192,7 @@ _GLIBCXX_HAS_NESTED_TYPE(result_type)
* reference_wrapper<F>, this function will not throw.
*/
template<typename _Functor>
- typename enable_if<!is_integral<_Functor>::value, function&>::type
+ _Requires<_Callable<_Functor>, function&>
operator=(_Functor&& __f)
{
function(std::forward<_Functor>(__f)).swap(*this);
@@ -2187,7 +2201,7 @@ _GLIBCXX_HAS_NESTED_TYPE(result_type)
/// @overload
template<typename _Functor>
- typename enable_if<!is_integral<_Functor>::value, function&>::type
+ function&
operator=(reference_wrapper<_Functor> __f) noexcept
{
function(__f).swap(*this);
@@ -2294,11 +2308,9 @@ _GLIBCXX_HAS_NESTED_TYPE(result_type)
}
template<typename _Res, typename... _ArgTypes>
- template<typename _Functor>
+ template<typename _Functor, typename>
function<_Res(_ArgTypes...)>::
- function(_Functor __f,
- typename enable_if<
- !is_integral<_Functor>::value, _Useless>::type)
+ function(_Functor __f)
: _Function_base()
{
typedef _Function_handler<_Signature_type, _Functor> _My_handler;
diff --git a/libstdc++-v3/testsuite/20_util/function/cons/callable.cc
b/libstdc++-v3/testsuite/20_util/function/cons/callable.cc
new file mode 100644
index 0000000..209c404
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/function/cons/callable.cc
@@ -0,0 +1,51 @@
+// { dg-options "-std=gnu++0x" }
+// { dg-do compile }
+
+// Copyright (C) 2012 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/>.
+
+#include <functional>
+#include <testsuite_hooks.h>
+
+void* f(std::function<void()>) { return nullptr; }
+int f(std::function<void(int)>) { return 1; }
+
+void test01()
+{
+ void* p __attribute__((unused));
+ int i __attribute__((unused));
+
+ p = f([] { });
+ i = f([] (int) { });
+}
+
+void g(std::function<void()>) { }
+void h(std::function<int(int)>) { }
+
+void test02()
+{
+ g([] { return "ignored"; });
+ h([] (char c) { return c; });
+}
+
+int main()
+{
+ test01();
+ test02();
+
+ return 0;
+}
