这是我尝试编译的代码的简短版本。
#include <iostream>
#include <functional>
#include <memory>
void foo(std::shared_ptr<int> b, unsigned int i)
{
std::cout << *b << " - " << i << std::endl;
}
int main()
{
using namespace std::placeholders;
typedef std::function<void(std::shared_ptr<int> b, unsigned int i)> Foo;
typedef std::function<void(unsigned int code)> Bar;
Foo f1 = foo;
Bar f2 = std::bind(f1, std::make_shared<int>(10), _1);
f2(0);
return 0;
}
g++-4.7 --version给出了g ++ - 4.7（GCC）4.7.1
g++-4.7 -std=c++11 test.cpp && ./a.out
10 - 0
c++ --version给出了Apple clang 4.0版（标签/ Apple / clang-421.0.60）（基于LLVM 3.1svn）
c++ -std=c++11 -stdlib=libc++ test.cpp
In file included from test.cpp:3:
In file included from /usr/bin/../lib/c++/v1/iostream:38:
In file included from /usr/bin/../lib/c++/v1/ios:216:
In file included from /usr/bin/../lib/c++/v1/__locale:18:
In file included from /usr/bin/../lib/c++/v1/mutex:177:
/usr/bin/../lib/c++/v1/functional:1642:8: error: no type named 'type' in 'std::__1::__invoke_of<std::__1::function<void (std::__1::shared_ptr<int>, unsigned int)> &,
std::__1::shared_ptr<int> &, std::__1::shared_ptr<int> &&>'
>::type type;
~~~^~~~
/usr/bin/../lib/c++/v1/functional:1721:18: note: in instantiation of template class 'std::__1::__bind_return<std::__1::function<void (std::__1::shared_ptr<int>, unsigned int)>,
std::__1::tuple<std::__1::shared_ptr<int>, std::__1::placeholders::__ph<1>>, std::__1::tuple<std::__1::shared_ptr<int> &&, unsigned int &&>>' requested here
typename __bind_return<_Fd, _Td, tuple<_Args&&...> >::type
^
/usr/bin/../lib/c++/v1/functional:1722:9: note: while substituting deduced template arguments into function template 'operator()'
[with _Args = <std::__1::shared_ptr<int>, unsigned int>]
operator()(_Args&& ...__args)
^
/usr/bin/../lib/c++/v1/type_traits:2971:1: note: while substituting deduced template arguments into function template '__invoke' [with _Fp = std::__1::__bind<std::__1::function<void
(std::__1::shared_ptr<int>, unsigned int)> &, std::__1::shared_ptr<int>, std::__1::placeholders::__ph<1> &> &, _Args = <no value>]
__invoke(_Fp&& __f, _Args&& ...__args)
^
/usr/bin/../lib/c++/v1/type_traits:2989:11: note: in instantiation of template class 'std::__1::__invokable_imp<std::__1::__bind<std::__1::function<void
(std::__1::shared_ptr<int>, unsigned int)> &, std::__1::shared_ptr<int>, std::__1::placeholders::__ph<1> &> &, std::__1::shared_ptr<int>, unsigned int>' requested here
__invokable_imp<_Fp, _Args...>::value>
^
/usr/bin/../lib/c++/v1/functional:1115:33: note: in instantiation of template class 'std::__1::__invokable<std::__1::__bind<std::__1::function<void
(std::__1::shared_ptr<int>, unsigned int)> &, std::__1::shared_ptr<int>, std::__1::placeholders::__ph<1> &> &, std::__1::shared_ptr<int>, unsigned int>' requested here
template <class _Fp, bool = __invokable<_Fp&, _ArgTypes...>::value>
^
/usr/bin/../lib/c++/v1/functional:1141:35: note: (skipping 13 contexts in backtrace; use -ftemplate-backtrace-limit=0 to see all)
typename enable_if<__callable<_Fp>::value>::type* = 0);
^
/usr/bin/../lib/c++/v1/memory:2218:20: note: in instantiation of template class 'std::__1::is_nothrow_move_constructible<std::__1::__bind<std::__1::function<void
(std::__1::shared_ptr<int>, unsigned int)> &, std::__1::shared_ptr<int>, std::__1::placeholders::__ph<1> &>>' requested here
_NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
^
/usr/bin/../lib/c++/v1/__config:253:34: note: expanded from macro '_NOEXCEPT_'
# define _NOEXCEPT_(x) noexcept(x)
^
/usr/bin/../lib/c++/v1/memory:2386:15: note: in instantiation of template class 'std::__1::__libcpp_compressed_pair_imp<std::__1::__bind<std::__1::function<void
(std::__1::shared_ptr<int>, unsigned int)> &, std::__1::shared_ptr<int>, std::__1::placeholders::__ph<1> &>, std::__1::allocator<std::__1::__bind<std::__1::function<void
(std::__1::shared_ptr<int>, unsigned int)> &, std::__1::shared_ptr<int>, std::__1::placeholders::__ph<1> &>>, 2>' requested here
: private __libcpp_compressed_pair_imp<_T1, _T2>
^
/usr/bin/../lib/c++/v1/functional:988:36: note: in instantiation of template class 'std::__1::__compressed_pair<std::__1::__bind<std::__1::function<void
(std::__1::shared_ptr<int>, unsigned int)> &, std::__1::shared_ptr<int>, std::__1::placeholders::__ph<1> &>, std::__1::allocator<std::__1::__bind<std::__1::function<void
(std::__1::shared_ptr<int>, unsigned int)> &, std::__1::shared_ptr<int>, std::__1::placeholders::__ph<1> &>>>' requested here
__compressed_pair<_Fp, _Alloc> __f_;
^
/usr/bin/../lib/c++/v1/functional:1273:13: note: in instantiation of template class 'std::__1::__function::__func<std::__1::__bind<std::__1::function<void
(std::__1::shared_ptr<int>, unsigned int)> &, std::__1::shared_ptr<int>, std::__1::placeholders::__ph<1> &>, std::__1::allocator<std::__1::__bind<std::__1::function<void
(std::__1::shared_ptr<int>, unsigned int)> &, std::__1::shared_ptr<int>, std::__1::placeholders::__ph<1> &>>, void (unsigned int)>' requested here
if (sizeof(_FF) <= sizeof(__buf_) && is_nothrow_copy_constructible<_Fp>::value)
^
test.cpp:21:12: note: in instantiation of function template specialization 'std::__1::function<void (unsigned int)>::function<std::__1::__bind<std::__1::function<void
(std::__1::shared_ptr<int>, unsigned int)> &, std::__1::shared_ptr<int>, std::__1::placeholders::__ph<1> &> >' requested here
Bar f2 = std::bind(f1, std::make_shared<int>(10), _1);
^
1 error generated.
我的代码有问题吗？
感谢。
答案 0 :(得分：5)
抱歉这个错误。
这看起来像是重复：
http://llvm.org/bugs/show_bug.cgi?id=15295
这是修补它的补丁：
Index: include/functional
===================================================================
--- include/functional (revision 175515)
+++ include/functional (working copy)
@@ -1624,16 +1624,38 @@
: public ____mu_return<_Ti,
__is_reference_wrapper<_Ti>::value,
is_bind_expression<_Ti>::value,
- 0 < is_placeholder<_Ti>::value,
+ 0 < is_placeholder<_Ti>::value &&
+ is_placeholder<_Ti>::value <= tuple_size<_TupleUj>::value,
_TupleUj>
{
};
template <class _Fp, class _BoundArgs, class _TupleUj>
+struct _is_valid_bind_return
+{
+ static const bool value = false;
+};
+
+template <class _Fp, class ..._BoundArgs, class _TupleUj>
+struct _is_valid_bind_return<_Fp, tuple<_BoundArgs...>, _TupleUj>
+{
+ static const bool value = __invokable<_Fp,
+ typename __mu_return<_BoundArgs, _TupleUj>::type...>::value;
+};
+
+template <class _Fp, class ..._BoundArgs, class _TupleUj>
+struct _is_valid_bind_return<_Fp, const tuple<_BoundArgs...>, _TupleUj>
+{
+ static const bool value = __invokable<_Fp,
+ typename __mu_return<const _BoundArgs, _TupleUj>::type...>::value;
+};
+
+template <class _Fp, class _BoundArgs, class _TupleUj,
+ bool = _is_valid_bind_return<_Fp, _BoundArgs, _TupleUj>::value>
struct __bind_return;
template <class _Fp, class ..._BoundArgs, class _TupleUj>
-struct __bind_return<_Fp, tuple<_BoundArgs...>, _TupleUj>
+struct __bind_return<_Fp, tuple<_BoundArgs...>, _TupleUj, true>
{
typedef typename __invoke_of
<
@@ -1647,7 +1669,7 @@
};
template <class _Fp, class ..._BoundArgs, class _TupleUj>
-struct __bind_return<_Fp, const tuple<_BoundArgs...>, _TupleUj>
+struct __bind_return<_Fp, const tuple<_BoundArgs...>, _TupleUj, true>
{
typedef typename __invoke_of
<
@@ -1673,8 +1695,10 @@
class __bind
: public __weak_result_type<typename decay<_Fp>::type>
{
+protected:
typedef typename decay<_Fp>::type _Fd;
typedef tuple<typename decay<_BoundArgs>::type...> _Td;
+private:
_Fd __f_;
_Td __bound_args_;
@@ -1731,7 +1755,7 @@
template <class ..._Args>
_LIBCPP_INLINE_VISIBILITY
- typename __bind_return<_Fd, _Td, tuple<_Args&&...> >::type
+ typename __bind_return<const _Fd, const _Td, tuple<_Args&&...> >::type
operator()(_Args&& ...__args) const
{
return __apply_functor(__f_, __bound_args_, __indices(),
@@ -1747,6 +1771,8 @@
: public __bind<_Fp, _BoundArgs...>
{
typedef __bind<_Fp, _BoundArgs...> base;
+ typedef typename base::_Fd _Fd;
+ typedef typename base::_Td _Td;
public:
typedef _Rp result_type;
@@ -1784,7 +1810,12 @@
template <class ..._Args>
_LIBCPP_INLINE_VISIBILITY
- result_type
+ typename enable_if
+ <
+ is_convertible<typename __bind_return<_Fd, _Td, tuple<_Args&&...> >::type,
+ result_type>::value,
+ result_type
+ >::type
operator()(_Args&& ...__args)
{
return base::operator()(_VSTD::forward<_Args>(__args)...);
@@ -1792,7 +1823,12 @@
template <class ..._Args>
_LIBCPP_INLINE_VISIBILITY
- result_type
+ typename enable_if
+ <
+ is_convertible<typename __bind_return<const _Fd, const _Td, tuple<_Args&&...> >::type,
+ result_type>::value,
+ result_type
+ >::type
operator()(_Args&& ...__args) const
{
return base::operator()(_VSTD::forward<_Args>(__args)...);
答案 1 :(得分：1)
它适用于使用clang 3.2的Ubuntu（listdc ++而不是libc ++），所以它在你的代码中没有问题。