@@ -127,7 +127,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
&& __alignof__(_Functor) <= _M_max_align
&& (_M_max_align % __alignof__(_Functor) == 0));
- typedef integral_constant<bool, __stored_locally> _Local_storage;
+ using _Local_storage = integral_constant<bool, __stored_locally>;
// Retrieve a pointer to the function object
static _Functor*
@@ -142,32 +142,33 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return __source._M_access<_Functor*>();
}
- // Clone a location-invariant function object that fits within
+ private:
+ // Construct a location-invariant function object that fits within
// an _Any_data structure.
- static void
- _M_clone(_Any_data& __dest, const _Any_data& __source, true_type)
- {
- ::new (__dest._M_access()) _Functor(__source._M_access<_Functor>());
- }
+ template<typename _Fn>
+ static void
+ _M_create(_Any_data& __dest, _Fn&& __f, true_type)
+ {
+ ::new (__dest._M_access()) _Functor(std::forward<_Fn>(__f));
+ }
- // Clone a function object that is not location-invariant or
- // that cannot fit into an _Any_data structure.
- static void
- _M_clone(_Any_data& __dest, const _Any_data& __source, false_type)
- {
- __dest._M_access<_Functor*>() =
- new _Functor(*__source._M_access<const _Functor*>());
- }
+ // Construct a function object on the heap and store a pointer.
+ template<typename _Fn>
+ static void
+ _M_create(_Any_data& __dest, _Fn&& __f, false_type)
+ {
+ __dest._M_access<_Functor*>()
+ = new _Functor(std::forward<_Fn>(__f));
+ }
- // Destroying a location-invariant object may still require
- // destruction.
+ // Destroy an object stored in the internal buffer.
static void
_M_destroy(_Any_data& __victim, true_type)
{
__victim._M_access<_Functor>().~_Functor();
}
- // Destroying an object located on the heap.
+ // Destroy an object located on the heap.
static void
_M_destroy(_Any_data& __victim, false_type)
{
@@ -188,12 +189,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__dest._M_access<const type_info*>() = nullptr;
#endif
break;
+
case __get_functor_ptr:
__dest._M_access<_Functor*>() = _M_get_pointer(__source);
break;
case __clone_functor:
- _M_clone(__dest, __source, _Local_storage());
+ _M_init_functor(__dest,
+ *const_cast<const _Functor*>(_M_get_pointer(__source)));
break;
case __destroy_functor:
@@ -203,9 +206,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return false;
}
- static void
- _M_init_functor(_Any_data& __functor, _Functor&& __f)
- { _M_init_functor(__functor, std::move(__f), _Local_storage()); }
+ template<typename _Fn>
+ static void
+ _M_init_functor(_Any_data& __functor, _Fn&& __f)
+ noexcept(__and_<_Local_storage,
+ is_nothrow_constructible<_Functor, _Fn>>::value)
+ {
+ _M_create(__functor, std::forward<_Fn>(__f), _Local_storage());
+ }
template<typename _Signature>
static bool
@@ -226,15 +234,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static bool
_M_not_empty_function(const _Tp&)
{ return true; }
-
- private:
- static void
- _M_init_functor(_Any_data& __functor, _Functor&& __f, true_type)
- { ::new (__functor._M_access()) _Functor(std::move(__f)); }
-
- static void
- _M_init_functor(_Any_data& __functor, _Functor&& __f, false_type)
- { __functor._M_access<_Functor*>() = new _Functor(std::move(__f)); }
};
_Function_base() = default;
@@ -291,6 +290,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return std::__invoke_r<_Res>(*_Base::_M_get_pointer(__functor),
std::forward<_ArgTypes>(__args)...);
}
+
+ template<typename _Fn>
+ static constexpr bool
+ _S_nothrow_init() noexcept
+ {
+ return __and_<typename _Base::_Local_storage,
+ is_nothrow_constructible<_Functor, _Fn>>::value;
+ }
};
// Specialization for invalid types
@@ -329,19 +336,26 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
: public _Maybe_unary_or_binary_function<_Res, _ArgTypes...>,
private _Function_base
{
+ // Equivalent to std::decay_t except that it produces an invalid type
+ // if the decayed type is the current specialization of std::function.
template<typename _Func,
- typename _Res2 = __invoke_result<_Func&, _ArgTypes...>>
+ bool _Self = is_same<__remove_cvref_t<_Func>, function>::value>
+ using _Decay_t
+ = typename __enable_if_t<!_Self, decay<_Func>>::type;
+
+ template<typename _Func,
+ typename _DFunc = _Decay_t<_Func>,
+ typename _Res2 = __invoke_result<_DFunc&, _ArgTypes...>>
struct _Callable
: __is_invocable_impl<_Res2, _Res>::type
{ };
- // Used so the return type convertibility checks aren't done when
- // performing overload resolution for copy construction/assignment.
- template<typename _Tp>
- struct _Callable<function, _Tp> : false_type { };
+ template<typename _Cond, typename _Tp = void>
+ using _Requires = __enable_if_t<_Cond::value, _Tp>;
- template<typename _Cond, typename _Tp>
- using _Requires = typename enable_if<_Cond::value, _Tp>::type;
+ template<typename _Functor>
+ using _Handler
+ = _Function_handler<_Res(_ArgTypes...), __decay_t<_Functor>>;
public:
typedef _Res result_type;
@@ -416,23 +430,26 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* If @a __f is a non-NULL function pointer or an object of type @c
* reference_wrapper<F>, this function will not throw.
*/
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 2774. std::function construction vs assignment
template<typename _Functor,
- typename = _Requires<__not_<is_same<_Functor, function>>, void>,
- typename = _Requires<_Callable<_Functor>, void>>
- function(_Functor __f)
+ typename = _Requires<_Callable<_Functor>>>
+ function(_Functor&& __f)
+ noexcept(_Handler<_Functor>::template _S_nothrow_init<_Functor>())
: _Function_base()
{
- static_assert(is_copy_constructible<_Functor>::value,
+ static_assert(is_copy_constructible<__decay_t<_Functor>>::value,
"std::function target must be copy-constructible");
- static_assert(is_constructible<_Functor, _Functor>::value,
+ static_assert(is_constructible<__decay_t<_Functor>, _Functor>::value,
"std::function target must be constructible from the "
"constructor argument");
- using _My_handler = _Function_handler<_Res(_ArgTypes...), _Functor>;
+ using _My_handler = _Handler<_Functor>;
if (_My_handler::_M_not_empty_function(__f))
{
- _My_handler::_M_init_functor(_M_functor, std::move(__f));
+ _My_handler::_M_init_functor(_M_functor,
+ std::forward<_Functor>(__f));
_M_invoker = &_My_handler::_M_invoke;
_M_manager = &_My_handler::_M_manager;
}
@@ -511,8 +528,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* reference_wrapper<F>, this function will not throw.
*/
template<typename _Functor>
- _Requires<_Callable<typename decay<_Functor>::type>, function&>
+ _Requires<_Callable<_Functor>, function&>
operator=(_Functor&& __f)
+ noexcept(_Handler<_Functor>::template _S_nothrow_init<_Functor>())
{
function(std::forward<_Functor>(__f)).swap(*this);
return *this;
new file mode 100644
@@ -0,0 +1,31 @@
+// { dg-do run { target c++11 } }
+#include <functional>
+#include <testsuite_hooks.h>
+
+struct Funk
+{
+ Funk() = default;
+ Funk(const Funk&) { ++copies; }
+ Funk(Funk&&) { ++moves; }
+
+ void operator()() const { }
+
+ static int copies;
+ static int moves;
+};
+
+int Funk::copies = 0;
+int Funk::moves = 0;
+
+int main()
+{
+ Funk e;
+ // LWG 2774 means there should be no move here:
+ std::function<void()> fc(e);
+ VERIFY(Funk::copies == 1);
+ VERIFY(Funk::moves == 0);
+ // And only one move here:
+ std::function<void()> fm(std::move(e));
+ VERIFY(Funk::copies == 1);
+ VERIFY(Funk::moves == 1);
+}
new file mode 100644
@@ -0,0 +1,37 @@
+// { dg-do compile { target c++11 } }
+#include <functional>
+
+struct X
+{
+ void operator()(X*);
+
+ char bigness[100];
+};
+
+using F = std::function<void(X*)>;
+
+static_assert( std::is_nothrow_constructible<F>::value, "" );
+static_assert( std::is_nothrow_constructible<F, F>::value, "" );
+static_assert( ! std::is_nothrow_constructible<F, F&>::value, "" );
+static_assert( ! std::is_nothrow_constructible<F, const F&>::value, "" );
+static_assert( std::is_nothrow_constructible<F, std::nullptr_t>::value, "" );
+
+static_assert( ! std::is_nothrow_constructible<F, X>::value, "" );
+using R = std::reference_wrapper<X>;
+static_assert( std::is_nothrow_constructible<F, R>::value, "" );
+
+
+// The standard requires that construction from a function pointer type
+// does not throw, but doesn't require that the construction is noexcept.
+// Strengthening that noexcept for these types is a GCC extension.
+static_assert( std::is_nothrow_constructible<F, void(*)(X*)>::value, "" );
+// This is a GCC extension, not required by the standard:
+static_assert( std::is_nothrow_constructible<F, void(&)(X*)>::value, "" );
+// This is a GCC extension, not required by the standard:
+static_assert( std::is_nothrow_constructible<F, void(X::*)()>::value, "" );
+
+auto c = [](X*){};
+static_assert( std::is_nothrow_constructible<F, decltype(+c)>::value, "" );
+// The standard allows this to throw, but as a GCC extenension we store
+// closures with no captures in the std::function, so this is noexcept too:
+static_assert( std::is_nothrow_constructible<F, decltype(c)>::value, "" );