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I'm getting the following errors when trying compile my HuffmanNode class for an assignment, it seems to be something to do with the shared_ptrs in the class, but I have no idea as to what is actually going wrong because of the sheer amount of text that I can't seem to find the actual problem.
g++ -std=c++11 -c src/HuffmanNode.cpp -o obj/HuffmanNode.o -I headers
In file included from /usr/include/x86_64-linux-gnu/c++/7/bits/c++allocator.h:33:0,
from /usr/include/c++/7/bits/allocator.h:46,
from /usr/include/c++/7/memory:63,
from headers/HuffmanNode.hpp:9,
from src/HuffmanNode.cpp:5:
/usr/include/c++/7/ext/new_allocator.h: In instantiation of ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Up*, _Args&& ...) [with _Up = FLNRHE001::HuffmanNode; _Args = {const std::shared_ptr<FLNRHE001::HuffmanNode>&}; _Tp = FLNRHE001::HuffmanNode]’:
/usr/include/c++/7/bits/alloc_traits.h:475:4: required from ‘static void std::allocator_traits<std::allocator<_Tp1> >::construct(std::allocator_traits<std::allocator<_Tp1> >::allocator_type&, _Up*, _Args&& ...) [with _Up = FLNRHE001::HuffmanNode; _Args = {const std::shared_ptr<FLNRHE001::HuffmanNode>&}; _Tp = FLNRHE001::HuffmanNode; std::allocator_traits<std::allocator<_Tp1> >::allocator_type = std::allocator<FLNRHE001::HuffmanNode>]’
/usr/include/c++/7/bits/shared_ptr_base.h:526:39: required from ‘std::_Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp>::_Sp_counted_ptr_inplace(_Alloc, _Args&& ...) [with _Args = {const std::shared_ptr<FLNRHE001::HuffmanNode>&}; _Tp = FLNRHE001::HuffmanNode; _Alloc = std::allocator<FLNRHE001::HuffmanNode>; __gnu_cxx::_Lock_policy _Lp = (__gnu_cxx::_Lock_policy)2]’
/usr/include/c++/7/bits/shared_ptr_base.h:637:4: required from ‘std::__shared_count<_Lp>::__shared_count(std::_Sp_make_shared_tag, _Tp*, const _Alloc&, _Args&& ...) [with _Tp = FLNRHE001::HuffmanNode; _Alloc = std::allocator<FLNRHE001::HuffmanNode>; _Args = {const std::shared_ptr<FLNRHE001::HuffmanNode>&}; __gnu_cxx::_Lock_policy _Lp = (__gnu_cxx::_Lock_policy)2]’
/usr/include/c++/7/bits/shared_ptr_base.h:1295:35: required from ‘std::__shared_ptr<_Tp, _Lp>::__shared_ptr(std::_Sp_make_shared_tag, const _Alloc&, _Args&& ...) [with _Alloc = std::allocator<FLNRHE001::HuffmanNode>; _Args = {const std::shared_ptr<FLNRHE001::HuffmanNode>&}; _Tp = FLNRHE001::HuffmanNode; __gnu_cxx::_Lock_policy _Lp = (__gnu_cxx::_Lock_policy)2]’
/usr/include/c++/7/bits/shared_ptr.h:344:64: required from ‘std::shared_ptr<_Tp>::shared_ptr(std::_Sp_make_shared_tag, const _Alloc&, _Args&& ...) [with _Alloc = std::allocator<FLNRHE001::HuffmanNode>; _Args = {const std::shared_ptr<FLNRHE001::HuffmanNode>&}; _Tp = FLNRHE001::HuffmanNode]’
/usr/include/c++/7/bits/shared_ptr.h:690:14: required from ‘std::shared_ptr<_Tp> std::allocate_shared(const _Alloc&, _Args&& ...) [with _Tp = FLNRHE001::HuffmanNode; _Alloc = std::allocator<FLNRHE001::HuffmanNode>; _Args = {const std::shared_ptr<FLNRHE001::HuffmanNode>&}]’
/usr/include/c++/7/bits/shared_ptr.h:706:39: required from ‘std::shared_ptr<_Tp> std::make_shared(_Args&& ...) [with _Tp = FLNRHE001::HuffmanNode; _Args = {const std::shared_ptr<FLNRHE001::HuffmanNode>&}]’
src/HuffmanNode.cpp:34:72: required from here
/usr/include/c++/7/ext/new_allocator.h:136:4: error: no matching function for call to ‘FLNRHE001::HuffmanNode::HuffmanNode(const std::shared_ptr<FLNRHE001::HuffmanNode>&)’
{ ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/HuffmanNode.cpp:41:1: note: candidate: FLNRHE001::HuffmanNode::HuffmanNode(FLNRHE001::HuffmanNode&&)
HuffmanNode::HuffmanNode(HuffmanNode &&n)
^~~~~~~~~~~
src/HuffmanNode.cpp:41:1: note: no known conversion for argument 1 from ‘const std::shared_ptr<FLNRHE001::HuffmanNode>’ to ‘FLNRHE001::HuffmanNode&&’
src/HuffmanNode.cpp:33:1: note: candidate: FLNRHE001::HuffmanNode::HuffmanNode(const FLNRHE001::HuffmanNode&)
HuffmanNode::HuffmanNode(const HuffmanNode &n)
^~~~~~~~~~~
src/HuffmanNode.cpp:33:1: note: no known conversion for argument 1 from ‘const std::shared_ptr<FLNRHE001::HuffmanNode>’ to ‘const FLNRHE001::HuffmanNode&’
src/HuffmanNode.cpp:11:1: note: candidate: FLNRHE001::HuffmanNode::HuffmanNode(char, int, std::shared_ptr<FLNRHE001::HuffmanNode>, std::shared_ptr<FLNRHE001::HuffmanNode>)
HuffmanNode::HuffmanNode(char c, int f, std::shared_ptr<HuffmanNode> l, std::shared_ptr<HuffmanNode> r)
^~~~~~~~~~~
src/HuffmanNode.cpp:11:1: note: candidate expects 4 arguments, 1 provided
In file included from /usr/include/x86_64-linux-gnu/c++/7/bits/c++allocator.h:33:0,
from /usr/include/c++/7/bits/allocator.h:46,
from /usr/include/c++/7/memory:63,
from headers/HuffmanNode.hpp:9,
from src/HuffmanNode.cpp:5:
/usr/include/c++/7/ext/new_allocator.h: In instantiation of ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Up*, _Args&& ...) [with _Up = FLNRHE001::HuffmanNode; _Args = {std::shared_ptr<FLNRHE001::HuffmanNode>&}; _Tp
= FLNRHE001::HuffmanNode]’:
/usr/include/c++/7/bits/alloc_traits.h:475:4: required from ‘static void std::allocator_traits<std::allocator<_Tp1> >::construct(std::allocator_traits<std::allocator<_Tp1> >::allocator_type&, _Up*, _Args&& ...) [with _Up = FLNRHE001::HuffmanNode; _Args = {std::shared_ptr<FLNRHE001::HuffmanNode>&}; _Tp = FLNRHE001::HuffmanNode; std::allocator_traits<std::allocator<_Tp1> >::allocator_type = std::allocator<FLNRHE001::HuffmanNode>]’
/usr/include/c++/7/bits/shared_ptr_base.h:526:39: required from ‘std::_Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp>::_Sp_counted_ptr_inplace(_Alloc, _Args&& ...) [with _Args = {std::shared_ptr<FLNRHE001::HuffmanNode>&};
_Tp = FLNRHE001::HuffmanNode; _Alloc = std::allocator<FLNRHE001::HuffmanNode>; __gnu_cxx::_Lock_policy _Lp = (__gnu_cxx::_Lock_policy)2]’
/usr/include/c++/7/bits/shared_ptr_base.h:637:4: required from ‘std::__shared_count<_Lp>::__shared_count(std::_Sp_make_shared_tag, _Tp*, const _Alloc&, _Args&& ...) [with _Tp = FLNRHE001::HuffmanNode; _Alloc = std::allocator<FLNRHE001::HuffmanNode>; _Args = {std::shared_ptr<FLNRHE001::HuffmanNode>&}; __gnu_cxx::_Lock_policy _Lp = (__gnu_cxx::_Lock_policy)2]’
/usr/include/c++/7/bits/shared_ptr_base.h:1295:35: required from ‘std::__shared_ptr<_Tp, _Lp>::__shared_ptr(std::_Sp_make_shared_tag, const _Alloc&, _Args&& ...) [with _Alloc = std::allocator<FLNRHE001::HuffmanNode>; _Args = {std::shared_ptr<FLNRHE001::HuffmanNode>&}; _Tp = FLNRHE001::HuffmanNode; __gnu_cxx::_Lock_policy _Lp = (__gnu_cxx::_Lock_policy)2]’
/usr/include/c++/7/bits/shared_ptr.h:344:64: required from ‘std::shared_ptr<_Tp>::shared_ptr(std::_Sp_make_shared_tag, const _Alloc&, _Args&& ...) [with _Alloc = std::allocator<FLNRHE001::HuffmanNode>; _Args = {std::shared_ptr<FLNRHE001::HuffmanNode>&}; _Tp = FLNRHE001::HuffmanNode]’
/usr/include/c++/7/bits/shared_ptr.h:690:14: required from ‘std::shared_ptr<_Tp> std::allocate_shared(const _Alloc&, _Args&& ...) [with _Tp = FLNRHE001::HuffmanNode; _Alloc = std::allocator<FLNRHE001::HuffmanNode>; _Args = {std::shared_ptr<FLNRHE001::HuffmanNode>&}]’
/usr/include/c++/7/bits/shared_ptr.h:706:39: required from ‘std::shared_ptr<_Tp> std::make_shared(_Args&& ...) [with _Tp = FLNRHE001::HuffmanNode; _Args = {std::shared_ptr<FLNRHE001::HuffmanNode>&}]’
src/HuffmanNode.cpp:93:52: required from here
/usr/include/c++/7/ext/new_allocator.h:136:4: error: no matching function for call to ‘FLNRHE001::HuffmanNode::HuffmanNode(std::shared_ptr<FLNRHE001::HuffmanNode>&)’
{ ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/HuffmanNode.cpp:41:1: note: candidate: FLNRHE001::HuffmanNode::HuffmanNode(FLNRHE001::HuffmanNode&&)
HuffmanNode::HuffmanNode(HuffmanNode &&n)
^~~~~~~~~~~
src/HuffmanNode.cpp:41:1: note: no known conversion for argument 1 from ‘std::shared_ptr<FLNRHE001::HuffmanNode>’ to ‘FLNRHE001::HuffmanNode&&’
src/HuffmanNode.cpp:33:1: note: candidate: FLNRHE001::HuffmanNode::HuffmanNode(const FLNRHE001::HuffmanNode&)
HuffmanNode::HuffmanNode(const HuffmanNode &n)
^~~~~~~~~~~
src/HuffmanNode.cpp:33:1: note: no known conversion for argument 1 from ‘std::shared_ptr<FLNRHE001::HuffmanNode>’ to ‘const FLNRHE001::HuffmanNode&’
src/HuffmanNode.cpp:11:1: note: candidate: FLNRHE001::HuffmanNode::HuffmanNode(char, int, std::shared_ptr<FLNRHE001::HuffmanNode>, std::shared_ptr<FLNRHE001::HuffmanNode>)
HuffmanNode::HuffmanNode(char c, int f, std::shared_ptr<HuffmanNode> l, std::shared_ptr<HuffmanNode> r)
^~~~~~~~~~~
src/HuffmanNode.cpp:11:1: note: candidate expects 4 arguments, 1 provided
I've tried looking up the errors but can't seem to find anything that solves the problem.
I can't post my entire code due to it being an assignment, but the lines that are mentioned in the error text are my constructor declarations, and as stated above, the problem seems to lie in the shared_ptrs:
line 11: HuffmanNode::HuffmanNode(char c, int f, std::shared_ptr<HuffmanNode> l, std::shared_ptr<HuffmanNode> r)
line 33: HuffmanNode::HuffmanNode(const HuffmanNode &n) : ch(n.ch), freq(n.freq), left(std::make_shared<HuffmanNode>(n.left)), right(std::make_shared<HuffmanNode>(n.right))
line 41: HuffmanNode::HuffmanNode(HuffmanNode &&n) : ch(std::move(n.ch)), freq(std::move(n.freq)), left(std::move(n.left)), right(std::move(n.right))
EDIT:
Here's what I can post according to the school regulations, the only method that has any content inside it of the problem areas is the move constructor, and that is just ensuring that there will be no double deletion errors when the destructor is called. This gives me the same errors as above does.
#include <memory>
class HuffmanNode
{
char ch;
int freq;
std::shared_ptr<HuffmanNode> left, right;
// Node constructor for leaf node
HuffmanNode(char c, int f, std::shared_ptr<HuffmanNode> l, std::shared_ptr<HuffmanNode> r)
: ch(c), freq(f), left(l), right(r)
{
// Handled in initialiser list
}
HuffmanNode(const HuffmanNode &n)
: ch(n.ch), freq(n.freq), left(std::make_shared<HuffmanNode>(n.left)),
right(std::make_shared<HuffmanNode>(n.right))
{
// Handled by initialiser list
}
// Move Constructor
HuffmanNode(HuffmanNode &&n)
: ch(std::move(n.ch)), freq(std::move(n.freq)),
left(std::move(n.left)),
right(std::move(n.right))
{
}
};
The errors were arising from attempting to use make_shared to create a copy of the left and right pointers, in this case I only require a shallow copy as is made by the shared_ptr copy constructor.
The corrected solution was only a change to the move constructor as follows-:
HuffmanNode(const HuffmanNode &n)
: ch(n.ch), freq(n.freq), left(n.left),
right(n.right)
{
// Handled by initialiser list
}
Thanks to Sam Varshavchik for the help in this!
Here's what I have so far for an example implementation of a custom constructor in the style of std::pair::pair(std::piecewise_construct_t, ...):
#include <tuple>
#include <string>
#include <utility>
#include <iostream>
struct A {
std::string m_a;
std::string m_b;
std::string m_c;
A() = default;
A(const A&) = default;
A(A&&) = default;
~A() = default;
template <typename T1, typename T2, typename T3>
A(T1&& a, T2&& b, T3&& c) :
m_a { std::forward<T1>(a) }, m_b { std::forward<T2>(b) }, m_c { std::forward<T3>(c) }
{ }
template <typename... T1, typename... T2, typename... T3,
std::size_t... I1, std::size_t... I2, std::size_t... I3>
A(std::tuple<T1...> args1,
std::tuple<T2...> args2,
std::tuple<T3...> args3,
std::integer_sequence<std::size_t, I1...>,
std::integer_sequence<std::size_t, I2...>,
std::integer_sequence<std::size_t, I3...>) :
m_a { std::forward<T1>(std::get<I1>(args1))... },
m_b { std::forward<T2>(std::get<I2>(args2))... },
m_c { std::forward<T3>(std::get<I3>(args3))... }
{ }
template <typename... T1, typename... T2, typename... T3>
A(std::piecewise_construct_t,
std::tuple<T1...> args1,
std::tuple<T2...> args2,
std::tuple<T3...> args3) :
A { args1, args2, args3,
std::make_index_sequence<sizeof...(T1)>{},
std::make_index_sequence<sizeof...(T2)>{},
std::make_index_sequence<sizeof...(T3)>{} }
{ }
};
int main() {
A a { std::piecewise_construct,
std::forward_as_tuple("abc"),
std::forward_as_tuple(10, 'd'),
std::forward_as_tuple("ef\0\0gh", 6)
};
std::cout << "m_a: " << a.m_a <<
"\nm_b: " << a.m_b <<
"\nm_c: " << a.m_c << '\n';
return 0;
}
Expected output (if piped through cat -v):
m_a: abc
m_b: dddddddddd
m_c: ef^#^#gh
However, gcc is still giving me errors that I can't quite decipher, which appear to be related to the internal implementation of std::tuple:
/tmp/from_tuple.cpp: In instantiation of ‘A::A(std::piecewise_construct_t, std::tuple<_Elements ...>, std::tuple<_Elements ...>, std::tuple<_Tail ...>) [with T1 = {const char (&)[4]}; T2 = {int&&, char&&}; T3 = {const char (&)[7], int&&}]’:
/tmp/from_tuple.cpp:51:11: required from here
/tmp/from_tuple.cpp:42:53: error: use of deleted function ‘constexpr std::tuple<_T1, _T2>::tuple(const std::tuple<_T1, _T2>&) [with _T1 = int&&; _T2 = char&&]’
std::make_index_sequence<sizeof...(T3)>{} }
^
In file included from /tmp/from_tuple.cpp:1:0:
/usr/include/c++/5/tuple:615:17: note: ‘constexpr std::tuple<_T1, _T2>::tuple(const std::tuple<_T1, _T2>&) [with _T1 = int&&; _T2 = char&&]’ is implicitly deleted because the default definition would be ill-formed:
constexpr tuple(const tuple&) = default;
^
/usr/include/c++/5/tuple:615:17: error: use of deleted function ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head, _Tail ...>&) [with long unsigned int _Idx = 0ul; _Head = int&&; _Tail = {char&&}]’
/usr/include/c++/5/tuple:215:17: note: ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head, _Tail ...>&) [with long unsigned int _Idx = 0ul; _Head = int&&; _Tail = {char&&}]’ is implicitly deleted because the default definition would be ill-formed:
constexpr _Tuple_impl(const _Tuple_impl&) = default;
^
/usr/include/c++/5/tuple:215:17: error: use of deleted function ‘constexpr std::_Tuple_impl<_Idx, _Head>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head>&) [with long unsigned int _Idx = 1ul; _Head = char&&]’
/usr/include/c++/5/tuple:364:17: note: ‘constexpr std::_Tuple_impl<_Idx, _Head>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head>&) [with long unsigned int _Idx = 1ul; _Head = char&&]’ is implicitly deleted because the default definition would be ill-formed:
constexpr _Tuple_impl(const _Tuple_impl&) = default;
^
/usr/include/c++/5/tuple:364:17: error: use of deleted function ‘constexpr std::_Head_base<_Idx, _Head, false>::_Head_base(const std::_Head_base<_Idx, _Head, false>&) [with long unsigned int _Idx = 1ul; _Head = char&&]’
/usr/include/c++/5/tuple:110:17: note: ‘constexpr std::_Head_base<_Idx, _Head, false>::_Head_base(const std::_Head_base<_Idx, _Head, false>&) [with long unsigned int _Idx = 1ul; _Head = char&&]’ is implicitly deleted because the default definition would be ill-formed:
constexpr _Head_base(const _Head_base&) = default;
^
/usr/include/c++/5/tuple:110:17: error: copying non-static data member ‘char&& std::_Head_base<1ul, char&&, false>::_M_head_impl’ of rvalue reference type
/usr/include/c++/5/tuple:215:17: error: use of deleted function ‘constexpr std::_Head_base<_Idx, _Head, false>::_Head_base(const std::_Head_base<_Idx, _Head, false>&) [with long unsigned int _Idx = 0ul; _Head = int&&]’
constexpr _Tuple_impl(const _Tuple_impl&) = default;
^
/usr/include/c++/5/tuple:110:17: note: ‘constexpr std::_Head_base<_Idx, _Head, false>::_Head_base(const std::_Head_base<_Idx, _Head, false>&) [with long unsigned int _Idx = 0ul; _Head = int&&]’ is implicitly deleted because the default definition would be ill-formed:
constexpr _Head_base(const _Head_base&) = default;
^
/usr/include/c++/5/tuple:110:17: error: copying non-static data member ‘int&& std::_Head_base<0ul, int&&, false>::_M_head_impl’ of rvalue reference type
/tmp/from_tuple.cpp:23:7: note: initializing argument 2 of ‘A::A(std::tuple<_Elements ...>, std::tuple<_Elements ...>, std::tuple<_Tail ...>, std::integer_sequence<long unsigned int, I1 ...>, std::integer_sequence<long unsigned int, I2 ...>, std::integer_sequence<long unsigned int, I3 ...>) [with T1 = {const char (&)[4]}; T2 = {int&&, char&&}; T3 = {const char (&)[7], int&&}; long unsigned int ...I1 = {0ul}; long unsigned int ...I2 = {0ul, 1ul}; long unsigned int ...I3 = {0ul, 1ul}]’
A(std::tuple<T1...> args1,
^
/tmp/from_tuple.cpp:42:53: error: use of deleted function ‘constexpr std::tuple<_T1, _T2>::tuple(const std::tuple<_T1, _T2>&) [with _T1 = const char (&)[7]; _T2 = int&&]’
std::make_index_sequence<sizeof...(T3)>{} }
^
In file included from /tmp/from_tuple.cpp:1:0:
/usr/include/c++/5/tuple:615:17: note: ‘constexpr std::tuple<_T1, _T2>::tuple(const std::tuple<_T1, _T2>&) [with _T1 = const char (&)[7]; _T2 = int&&]’ is implicitly deleted because the default definition would be ill-formed:
constexpr tuple(const tuple&) = default;
^
/usr/include/c++/5/tuple:615:17: error: use of deleted function ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head, _Tail ...>&) [with long unsigned int _Idx = 0ul; _Head = const char (&)[7]; _Tail = {int&&}]’
/usr/include/c++/5/tuple:215:17: note: ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head, _Tail ...>&) [with long unsigned int _Idx = 0ul; _Head = const char (&)[7]; _Tail = {int&&}]’ is implicitly deleted because the default definition would be ill-formed:
constexpr _Tuple_impl(const _Tuple_impl&) = default;
^
/usr/include/c++/5/tuple:215:17: error: use of deleted function ‘constexpr std::_Tuple_impl<_Idx, _Head>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head>&) [with long unsigned int _Idx = 1ul; _Head = int&&]’
/usr/include/c++/5/tuple:364:17: note: ‘constexpr std::_Tuple_impl<_Idx, _Head>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head>&) [with long unsigned int _Idx = 1ul; _Head = int&&]’ is implicitly deleted because the default definition would be ill-formed:
constexpr _Tuple_impl(const _Tuple_impl&) = default;
^
/usr/include/c++/5/tuple:364:17: error: use of deleted function ‘constexpr std::_Head_base<_Idx, _Head, false>::_Head_base(const std::_Head_base<_Idx, _Head, false>&) [with long unsigned int _Idx = 1ul; _Head = int&&]’
/usr/include/c++/5/tuple:110:17: note: ‘constexpr std::_Head_base<_Idx, _Head, false>::_Head_base(const std::_Head_base<_Idx, _Head, false>&) [with long unsigned int _Idx = 1ul; _Head = int&&]’ is implicitly deleted because the default definition would be ill-formed:
constexpr _Head_base(const _Head_base&) = default;
^
/usr/include/c++/5/tuple:110:17: error: copying non-static data member ‘int&& std::_Head_base<1ul, int&&, false>::_M_head_impl’ of rvalue reference type
/tmp/from_tuple.cpp:23:7: note: initializing argument 3 of ‘A::A(std::tuple<_Elements ...>, std::tuple<_Elements ...>, std::tuple<_Tail ...>, std::integer_sequence<long unsigned int, I1 ...>, std::integer_sequence<long unsigned int, I2 ...>, std::integer_sequence<long unsigned int, I3 ...>) [with T1 = {const char (&)[4]}; T2 = {int&&, char&&}; T3 = {const char (&)[7], int&&}; long unsigned int ...I1 = {0ul}; long unsigned int ...I2 = {0ul, 1ul}; long unsigned int ...I3 = {0ul, 1ul}]’
A(std::tuple<T1...> args1,
^
Whoops, it looks like I just needed a bit more patience looking at the error messages. If I'd just looked at the first one, it was telling me that std::tuple<int&&, char&&> has an implicitly deleted copy constructor, presumably because of the rvalue-reference members. So, if I change the overload taking dummy integer_sequence objects to take tuple references, then the example compiles.
But then, in the case of the second element, it looks like it's using the initializer_list constructor instead of the intended size_t, char constructor. Changing from brace-initializers to the old-style parenthesized initializers in the same overload fixed that.
So overall, replace that overload with:
template <typename... T1, typename... T2, typename... T3,
std::size_t... I1, std::size_t... I2, std::size_t... I3>
A(std::tuple<T1...>& args1,
std::tuple<T2...>& args2,
std::tuple<T3...>& args3,
std::integer_sequence<std::size_t, I1...>,
std::integer_sequence<std::size_t, I2...>,
std::integer_sequence<std::size_t, I3...>) :
m_a(std::forward<T1>(std::get<I1>(args1))...),
m_b(std::forward<T2>(std::get<I2>(args2))...),
m_c(std::forward<T3>(std::get<I3>(args3))...)
{ }
class taskq {
public:
int trigger(taskq &tq);
mutex mtx;
};
void func_wrapper(taskq &tq) {
cout<<endl;
}
int taskq::trigger(taskq &tq) {
thread thread(func_wrapper, tq);
return 0;
}
I tried to compile the above simple code but I am keep getting errors because of line thread thread(func_wrapper, tq);.
What's wrong with this code?
How could I fix it?
The error message is as below:
In file included from /usr/include/c++/4.9/thread:39:0,
from taskq.C:2:
/usr/include/c++/4.9/functional: In instantiation of ‘struct std::_Bind_simple<void (*(taskq))(taskq&)>’:
/usr/include/c++/4.9/thread:140:47: required from ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(taskq&); _Args = {taskq&}]’
taskq.C:20:33: required from here
/usr/include/c++/4.9/functional:1665:61: error: no type named ‘type’ in ‘class std::result_of<void (*(taskq))(taskq&)>’
typedef typename result_of<_Callable(_Args...)>::type result_type;
^
/usr/include/c++/4.9/functional:1695:9: error: no type named ‘type’ in ‘class std::result_of<void (*(taskq))(taskq&)>’
_M_invoke(_Index_tuple<_Indices...>)
^
In file included from /usr/include/c++/4.9/functional:55:0,
from /usr/include/c++/4.9/thread:39,
from taskq.C:2:
/usr/include/c++/4.9/tuple: In instantiation of ‘constexpr std::_Head_base<_Idx, _Head, false>::_Head_base(_UHead&&) [with _UHead = taskq; <template-parameter-2-2> = void; long unsigned int _Idx = 1ul; _Head = taskq]’:
/usr/include/c++/4.9/tuple:271:42: required from ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(std::_Tuple_impl<_Idx, _Head, _Tail ...>&&) [with long unsigned int _Idx = 1ul; _Head = taskq; _Tail = {}]’
/usr/include/c++/4.9/type_traits:900:43: required by substitution of ‘template<class _Tp, class _Arg, class> static std::true_type std::__do_is_direct_constructible_impl::__test(int) [with _Tp = std::_Tuple_impl<1ul, taskq>; _Arg = std::_Tuple_impl<1ul, taskq>&&; <template-parameter-1-3> = <missing>]’
/usr/include/c++/4.9/type_traits:912:43: required from ‘struct std::__is_direct_constructible_impl<std::_Tuple_impl<1ul, taskq>, std::_Tuple_impl<1ul, taskq>&&>’
/usr/include/c++/4.9/type_traits:134:12: required from ‘struct std::__and_<std::is_destructible<std::_Tuple_impl<1ul, taskq> >, std::__is_direct_constructible_impl<std::_Tuple_impl<1ul, taskq>, std::_Tuple_impl<1ul, taskq>&&> >’
/usr/include/c++/4.9/type_traits:916:12: required from ‘struct std::__is_direct_constructible_new_safe<std::_Tuple_impl<1ul, taskq>, std::_Tuple_impl<1ul, taskq>&&>’
/usr/include/c++/4.9/type_traits:994:12: [ skipping 7 instantiation contexts, use -ftemplate-backtrace-limit=0 to disable ]
/usr/include/c++/4.9/type_traits:1175:12: required from ‘struct std::is_nothrow_move_constructible<std::_Tuple_impl<1ul, taskq> >’
/usr/include/c++/4.9/type_traits:134:12: required from ‘struct std::__and_<std::is_nothrow_move_constructible<void (*)(taskq&)>, std::is_nothrow_move_constructible<std::_Tuple_impl<1ul, taskq> > >’
/usr/include/c++/4.9/tuple:267:7: required from ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(std::_Tuple_impl<_Idx, _Head, _Tail ...>&&) [with long unsigned int _Idx = 0ul; _Head = void (*)(taskq&); _Tail = {taskq}]’
/usr/include/c++/4.9/functional:1727:41: required from ‘typename std::_Bind_simple_helper<_Func, _BoundArgs>::__type std::__bind_simple(_Callable&&, _Args&& ...) [with _Callable = void (&)(taskq&); _Args = {taskq&}; typename std::_Bind_simple_helper<_Func, _BoundArgs>::__type = std::_Bind_simple<void (*(taskq))(taskq&)>]’
/usr/include/c++/4.9/thread:140:47: required from ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(taskq&); _Args = {taskq&}]’
taskq.C:20:33: required from here
/usr/include/c++/4.9/tuple:140:42: error: use of deleted function ‘taskq::taskq(taskq&&)’
: _M_head_impl(std::forward<_UHead>(__h)) { }
^
taskq.C:9:7: note: ‘taskq::taskq(taskq&&)’ is implicitly deleted because the default definition would be ill-formed:
class taskq {
^
taskq.C:9:7: error: use of deleted function ‘std::mutex::mutex(const std::mutex&)’
In file included from taskq.C:3:0:
/usr/include/c++/4.9/mutex:129:5: note: declared here
mutex(const mutex&) = delete;
^
In file included from /usr/include/c++/4.9/functional:55:0,
from /usr/include/c++/4.9/thread:39,
from taskq.C:2:
/usr/include/c++/4.9/tuple: In instantiation of ‘constexpr std::_Head_base<_Idx, _Head, false>::_Head_base(const _Head&) [with long unsigned int _Idx = 1ul; _Head = taskq]’:
/usr/include/c++/4.9/tuple:255:44: recursively required from ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const _Head&, const _Tail& ...) [with long unsigned int _Idx = 1ul; _Head = taskq; _Tail = {}]’
/usr/include/c++/4.9/tuple:255:44: required from ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const _Head&, const _Tail& ...) [with long unsigned int _Idx = 0ul; _Head = void (*)(taskq&); _Tail = {taskq}]’
/usr/include/c++/4.9/tuple:531:30: required from ‘constexpr std::tuple<_T1, _T2>::tuple(const _T1&, const _T2&) [with _T1 = void (*)(taskq&); _T2 = taskq]’
/usr/include/c++/4.9/functional:1678:74: required from ‘std::_Bind_simple<_Callable(_Args ...)>::_Bind_simple(_Callable&&, _Args2&& ...) [with _Args2 = {taskq&}; <template-parameter-2-2> = void; _Callable = void (*)(taskq&); _Args = {taskq}]’
/usr/include/c++/4.9/functional:1727:41: required from ‘typename std::_Bind_simple_helper<_Func, _BoundArgs>::__type std::__bind_simple(_Callable&&, _Args&& ...) [with _Callable = void (&)(taskq&); _Args = {taskq&}; typename std::_Bind_simple_helper<_Func, _BoundArgs>::__type = std::_Bind_simple<void (*(taskq))(taskq&)>]’
/usr/include/c++/4.9/thread:140:47: required from ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(taskq&); _Args = {taskq&}]’
taskq.C:20:33: required from here
/usr/include/c++/4.9/tuple:134:25: error: use of deleted function ‘taskq::taskq(const taskq&)’
: _M_head_impl(__h) { }
^
taskq.C:9:7: note: ‘taskq::taskq(const taskq&)’ is implicitly deleted because the default definition would be ill-formed:
class taskq {
^
taskq.C:9:7: error: use of deleted function ‘std::mutex::mutex(const std::mutex&)’
In file included from taskq.C:3:0:
/usr/include/c++/4.9/mutex:129:5: note: declared here
mutex(const mutex&) = delete;
^
make: *** [taskq.o] Error 1
thread thread(func_wrapper, std::ref(tq));
Note that you need to make sure the reference is still valid while you are executing func_wrapper (since I'm guessing such function uses tq).
std::thread thread([&tq]() {
func_wrapper(tq);
});
Before people start telling me to do a google search for my problem, let me say I've been trying for quite a while.
I can't figure out how to pass an object by reference in C++, I keep getting a massive printout of compiler errors. I can include them if they would help. Specifically, I'm trying to pass the RSSFeed object feed by reference to the function parseFeed in a thread.
void parseFeed(RSSFeed& feed) {
//dostuff
}
RSSFeed feed();
thread(parseFeed, feed); // line 119
errors:
g++ -g -Wall -pedantic -O0 -std=c++0x -D_GLIBCXX_USE_NANOSLEEP -D_GLIBCXX_USE_SCHED_YIELD -I/usr/class/cs110/include/libxml2 -I/usr/class/cs110/local/include -c -o news-aggregator.o news-aggregator.cc
In file included from /usr/include/c++/4.6/functional:56:0,
from /usr/include/c++/4.6/bits/stl_algo.h:68,
from /usr/include/c++/4.6/algorithm:63,
from news-aggregator.cc:14:
rss-feed.h: In constructor âconstexpr std::_Head_base<_Idx, _Head, false>::_Head_base(const _Head&) [with long unsigned int _Idx = 0ul, _Head = RSSFeed]â:
/usr/include/c++/4.6/tuple:162:44: instantiated from âconstexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const _Head&, const _Tail& ...) [with long unsigned int _Idx = 0ul, _Head = RSSFeed, _Tail = {}]â
/usr/include/c++/4.6/tuple:423:24: instantiated from âconstexpr std::tuple<_T1>::tuple(const _T1&) [with _T1 = RSSFeed]â
/usr/include/c++/4.6/functional:1362:70: instantiated from âstd::_Bind_result<_Result, _Functor(_Bound_args ...)>::_Bind_result(_Functor&&, _Args&& ...) [with _Args = {RSSFeed&}, _Result = void, _Functor = void (*)(RSSFeed&), _Bound_args = {RSSFeed}]â
/usr/include/c++/4.6/functional:1477:41: instantiated from âtypename std::_Bindres_helper<_Result, _Functor, _ArgTypes>::type std::bind(_Functor&&, _ArgTypes&& ...) [with _Result = void, _Functor = void (&)(RSSFeed&), _ArgTypes = {RSSFeed&}, typename std::_Bindres_helper<_Result, _Functor, _ArgTypes>::type = std::_Bind_result<void, void (*(RSSFeed))(RSSFeed&)>]â
/usr/include/c++/4.6/thread:135:9: instantiated from âstd::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(RSSFeed&), _Args = {RSSFeed&}]â
news-aggregator.cc:119:25: instantiated from here
rss-feed.h:54:3: error: âRSSFeed::RSSFeed(const RSSFeed&)â is private
/usr/include/c++/4.6/tuple:97:25: error: within this context
/usr/include/c++/4.6/tuple:97:25: error: use of deleted function âRSSFeed::RSSFeed(const RSSFeed&)â
rss-feed.h:54:3: error: declared here
rss-feed.h: In constructor âstd::_Head_base<_Idx, _Head, false>::_Head_base(_UHead&&) [with _UHead = RSSFeed, long unsigned int _Idx = 0ul, _Head = RSSFeed]â:
/usr/include/c++/4.6/tuple:174:43: instantiated from âstd::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(std::_Tuple_impl<_Idx, _Head, _Tail ...>&&) [with long unsigned int _Idx = 0ul, _Head = RSSFeed, _Tail = {}, std::_Tuple_impl<_Idx, _Head, _Tail ...> = std::_Tuple_impl<0ul, RSSFeed>]â
/usr/include/c++/4.6/tuple:434:51: instantiated from âstd::tuple<_T1>::tuple(std::tuple<_T1>&&) [with _T1 = RSSFeed, std::tuple<_T1> = std::tuple<RSSFeed>]â
/usr/include/c++/4.6/functional:1368:78: instantiated from âstd::_Bind_result<_Result, _Functor(_Bound_args ...)>::_Bind_result(std::_Bind_result<_Result, _Functor(_Bound_args ...)>&&) [with _Result = void, _Functor = void (*)(RSSFeed&), _Bound_args = {RSSFeed}, std::_Bind_result<_Result, _Functor(_Bound_args ...)> = std::_Bind_result<void, void (*(RSSFeed))(RSSFeed&)>]â
/usr/include/c++/4.6/functional:1477:41: instantiated from âtypename std::_Bindres_helper<_Result, _Functor, _ArgTypes>::type std::bind(_Functor&&, _ArgTypes&& ...) [with _Result = void, _Functor = void (&)(RSSFeed&), _ArgTypes = {RSSFeed&}, typename std::_Bindres_helper<_Result, _Functor, _ArgTypes>::type = std::_Bind_result<void, void (*(RSSFeed))(RSSFeed&)>]â
/usr/include/c++/4.6/thread:135:9: instantiated from âstd::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(RSSFeed&), _Args = {RSSFeed&}]â
news-aggregator.cc:119:25: instantiated from here
rss-feed.h:54:3: error: âRSSFeed::RSSFeed(const RSSFeed&)â is private
/usr/include/c++/4.6/tuple:101:42: error: within this context
/usr/include/c++/4.6/tuple:101:42: error: use of deleted function âRSSFeed::RSSFeed(const RSSFeed&)â
rss-feed.h:54:3: error: declared here
Resolved:
thread(parseFeed, ref( feed ) ); // line 119
This
RSSFeed feed();
is a function declaration that returns an object of type RSSFeed and has no parameters. It is not an object definition.
Write instead
RSSFeed feed;
Also it seems from the list of error messages that class RSSFeed has no the copy constructor that is it is defined as deleted.
#include <vector>
class B {
};
class A {
const std::vector<B> m_v;
public:
A(const std::vector<B>& v) : m_v(v) {}
void doSomething() {}
};
void foo(void* bar) {
A* a = (A*)bar;
a->doSomething();
}
int main() {
std::vector<B> v;
std::vector<A > l;
for (auto i = 0; i < 10; i++) {
A a(v);
l.push_back(std::move(a));
foo((void*)&l[i]);
}
return 0;
}
$ g++ -Wall initList.cpp -o initList -lrt -O3 -std=c++0x
In file included from /usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/vector:70:0,
from initList.cpp:1:
/usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/bits/vector.tcc: In member function \u2018void std::vector::_M_insert_aux(std::vector::iterator, _Args&& ...) [with _Args = {A}, _Tp = A, _Alloc = std::allocator, std::vector::iterator = __gnu_cxx::__normal_iterator >, typename std::_Vector_base::_Tp_alloc_type::pointer = A*]`:
/usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/bits/vector.tcc:102:4: instantiated from \u2018void std::vector::emplace_back(_Args&& ...) [with _Args = {A}, _Tp = A, _Alloc = std::allocator]`
/usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/bits/stl_vector.h:840:9: instantiated from \u2018void std::vector::push_back(std::vector::value_type&&) [with _Tp = A, _Alloc = std::allocator, std::vector::value_type = A]`
initList.cpp:23:27: instantiated from here
/usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/bits/vector.tcc:319:4: error: use of deleted function '& A::operator=(const A&)`
initList.cpp:6:7: error: '& A::operator=(const A&)` is implicitly deleted because the default definition would be ill-formed:
initList.cpp:6:7: error: passing \u2018const std::vector` as \u2018this` argument of \u2018std::vector& std::vector::operator=(const std::vector&) [with _Tp = B, _Alloc = std::allocator]` discards qualifiers [-fpermissive]
In file included from /usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/vector:61:0,
from initList.cpp:1:
/usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/bits/stl_algobase.h: In static member function \u2018static _BI2 std::__copy_move_backward::__copy_move_b(_BI1, _BI1, _BI2) [with _BI1 = A*, _BI2 = A*]`:
/usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/bits/stl_algobase.h:581:18: instantiated from \u2018_BI2 std::__copy_move_backward_a(_BI1, _BI1, _BI2) [with bool _IsMove = true, _BI1 = A*, _BI2 = A*]`
/usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/bits/stl_algobase.h:590:34: instantiated from \u2018_BI2 std::__copy_move_backward_a2(_BI1, _BI1, _BI2) [with bool _IsMove = true, _BI1 = A*, _BI2 = A*]`
/usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/bits/stl_algobase.h:661:15: instantiated from \u2018_BI2 std::move_backward(_BI1, _BI1, _BI2) [with _BI1 = A*, _BI2 = A*]`
/usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/bits/vector.tcc:313:4: instantiated from \u2018void std::vector::_M_insert_aux(std::vector::iterator, _Args&& ...) [with _Args = {A}, _Tp = A, _Alloc = std::allocator, std::vector::iterator = __gnu_cxx::__normal_iterator >, typename std::_Vector_base::_Tp_alloc_type::pointer = A*]`
/usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/bits/vector.tcc:102:4: instantiated from \u2018void std::vector::emplace_back(_Args&& ...) [with _Args = {A}, _Tp = A, _Alloc = std::allocator]`
/usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/bits/stl_vector.h:840:9: instantiated from \u2018void std::vector::push_back(std::vector::value_type&&) [with _Tp = A, _Alloc = std::allocator, std::vector::value_type = A]`
initList.cpp:23:27: instantiated from here
/usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../include/c++/4.6.2/bits/stl_algobase.h:546:6: error: use of deleted function '& A::operator=(const A&)`
If I don't specify const for m_v. It compiles fine.
The error suggests something with assign operator, which I don't see how it is invoked.
Any idea?
Thanks in advance.
It's a bug in older versions of GCC/libstdc++, your code compiles fine with GCC 4.8.1. Live example. The bug is triggered by
l.push_back(std::move(a));
as older versions of GCC tried to create a default-constructed element in the vector and assigned the parameter std::move(a) to it in a second step instead of using the in-place copy/move-ctor.