error: call of overloaded distance is ambiguous - c++

I have a bit of code (which I didn't write, but am trying to compile) -- iostream_combo.cc--, and doing so gives me the following error:
./moses/moses/comboreduct/combo/iostream_combo.cc: In function ‘std::__cxx11::string opencog::combo::l2ph(const string&, const std::vector<std::__cxx11::basic_string<char> >&)’:
./moses/moses/comboreduct/combo/iostream_combo.cc:543:64: error: call of overloaded ‘distance(std::vector<std::__cxx11::basic_string<char> >::const_iterator, __gnu_cxx::__normal_iterator<const std::__cxx11::basic_string<char>*, std::vector<std::__cxx11::basic_string<char> > >&)’ is ambiguous
arity_t idx = distance(labels.begin(), found_it) + 1;
^ In file included from /usr/include/c++/8/bits/stl_algobase.h:66,
from /usr/include/c++/8/bits/char_traits.h:39,
from /usr/include/c++/8/ios:40,
from /usr/include/c++/8/ostream:38,
from /usr/include/c++/8/iostream:39,
from ./moses/moses/comboreduct/combo/iostream_combo.h:28,
from ./moses/moses/comboreduct/combo/iostream_combo.cc:24:
/usr/include/c++/8/bits/stl_iterator_base_funcs.h:138:5: note: candidate: ‘typename std::iterator_traits<_Iterator>::difference_type std::distance(_InputIterator, _InputIterator) [with _InputIterator = __gnu_cxx::__normal_iterator<const std::__cxx11::basic_string<char>*, std::vector<std::__cxx11::basic_string<char> > >; typename std::iterator_traits<_Iterator>::difference_type = long int]’
distance(_InputIterator __first, _InputIterator __last)
^~~~~~~~ In file included from /usr/local/include/boost/range/distance.hpp:18,
from /usr/local/include/boost/range/functions.hpp:21,
from /usr/local/include/boost/range/iterator_range_core.hpp:38,
from /usr/local/include/boost/lexical_cast.hpp:30,
from ./moses/moses/comboreduct/combo/iostream_combo.h:30,
from ./moses/moses/comboreduct/combo/iostream_combo.cc:24:
/usr/local/include/boost/iterator/distance.hpp:49:9: note: candidate: ‘constexpr typename boost::iterators::iterator_difference<Iterator>::type boost::iterators::distance_adl_barrier::distance(SinglePassIterator, SinglePassIterator) [with SinglePassIterator = __gnu_cxx::__normal_iterator<const std::__cxx11::basic_string<char>*, std::vector<std::__cxx11::basic_string<char> > >; typename boost::iterators::iterator_difference<Iterator>::type = long int]’
distance(SinglePassIterator first, SinglePassIterator last)
^~~~~~~~
I'm using Ubuntu 16.04 x64, Boost 1.68 and gcc 8.2. So, the steps to reproduce the problem would be as follows:
On Ubuntu 16.04
install gcc-8
Use it to build boost 1.68 from source
Git clone the moses repository sand follow the instructions from there: basically 1) git clone and build cogutil; 2) try to make moses:
cd build, cmake .., make.
I understand C++ enough (I think) that I can see that the call to std::distance is overloaded. What I don't see is the way to disambiguate it, although I guess it must include some re-writing of found_it or some explicit castings instead of auto.

The calls are like:
arity_t idx = distance(labels.begin(), found_it) + 1;
This means that distance is found via ADL and hence all associated namespaces are considered. This might prove problematic if e.g. there are two namespaces providing an equally applicable overload for distance:
Live On Coliru
#include <iterator>
#include <vector>
namespace OyVeh {
struct X { };
template <typename It>
size_t distance(It, It) { return 42; } // just to throw in a wrench
}
int main() {
std::vector<OyVeh::X> v{3};
auto f = v.begin();
auto l = v.end();
// now f and l have both `::std` and `::OyVeh` as associated namespaces. The following is ambiguous:
return distance(f, l);
}
There are roughly 2 ways to fix it:
remove the ambigious distance declaration from the associated namespace (this might not be possible if e.g. the ones competing are std::distance and boost::distance)
edit the calls to remove the reliance on ADL (e.g. qualify them like std::distance(...) or parenthesize them (distance)(...))
Showing the workarounds:
Live On Coliru
{
using OyVeh::distance;
return (distance)(f, l); // parentheses suppress ADL
}
return std::distance(f, l); // also works, obviously
return OyVeh::distance(f, l); // but beware the meaning might change

Related

STL vector.insert method expects _InputIterator as the arguments

I have the following code:
typedef unsigned long int U64;
std::vector<U64> vectorA;
std::vector<U64> vectorB;
vectorA.insert(vectorA.end(), vectorB.begin(), vectorB.end());
I'm getting compilation error at the last line, it could not find the method.
It expects following signature (code from stl_vector.h):
template<typename _InputIterator,
typename = std::_RequireInputIter<_InputIterator>>
iterator
insert(const_iterator __position, _InputIterator __first,
_InputIterator __last)
How can I get the instance of the _InputIterator / _RequireInputIter for the instance of vector class?
Can I do the same using different method?
I'm using gcc:
gcc version 7.0.1 20170407 (experimental) [trunk revision 246759]
(Ubuntu 7-20170407-0ubuntu2)
and Ubuntu:
NAME="Ubuntu" VERSION="17.04 (Zesty Zapus)"
edit:
I'm getting compilation error:
Invalid arguments ' Candidates are:
__gnu_cxx::__normal_iterator<int *,std::vector<int,std::allocator<int>>> insert(__gnu_cxx::__normal_iterator<const int
*,std::vector<int,std::allocator<int>>>, const int &)
__gnu_cxx::__normal_iterator<int *,std::vector<int,std::allocator<int>>> insert(__gnu_cxx::__normal_iterator<const int
*,std::vector<int,std::allocator<int>>>, int &&)
__gnu_cxx::__normal_iterator<int *,std::vector<int,std::allocator<int>>> insert(__gnu_cxx::__normal_iterator<const int
*,std::vector<int,std::allocator<int>>>, std::initializer_list<int>)
__gnu_cxx::__normal_iterator<int *,std::vector<int,std::allocator<int>>> insert
Ths code compiles and works without error. Tested with https://wandbox.org/
#include <vector>
#include <iostream>
typedef unsigned long int U64;
int main()
{
std::vector<U64> vectorA = { 3, 4};
std::vector<U64> vectorB = { 5, 7};
vectorA.insert(vectorA.end(), vectorB.begin(), vectorB.end());
for (const auto& i: vectorA)
std::cout << i << ' ';
}
There is something you're not telling us.
Be aware that what is used here is NOT STL. STL is a legacy library that was created in 90s. What we are using now is standard C++ library which is based on STL and boost to extent. STL is still around for historical reasons. But STL doesn't comply to C++ standard. Something is wrong with include paths or with toolchain. It possible that you actually try to compile with vanilla STL headers, or some headers were mixed up with boost headers.

declaring / compiling 2d vector of vectors

A colleague has provided me with a package of c++ code based on some Celestrak satellite code https://celestrak.org/software/vallado/cpp.zip.
In several places the code, i.e coordfk5.cpp declares vectors of vectors like
std::vector< std::vector<double> > prec, nut(3,3), st, stdot, pm, pmp
The nut(3,3) and similar declarations won't compile on my system yet does for the colleague on his and presumably others who have downloaded the original package.
stl_vector.h: In instantiation of 'void std::vector<_Tp, _Alloc>::_M_initialize_dispatch(_Integer, _Integer, std::__true_type) [with _Integer = int; _Tp = std::vector; _Alloc = std::allocatorstd::vector<double >]':
stl_vector.h:404:55: required from 'std::vector<_Tp, _Alloc>::vector(_InputIterator, _InputIterator, const allocator_type&) [with _InputIterator = int; _Tp = std::vector; _Alloc = std::allocatorstd::vector<double >; std::vector<_Tp, _Alloc>::allocator_type = std::allocatorstd::vector<double >]'
stl_vector.h:1166:59: error: no matching function for call to 'std::vectorstd::vector<double >::_M_fill_initialize(std::vectorstd::vector<double >::size_type, int&)'
_M_fill_initialize(static_cast<size_type>(__n), __value);
I'm on gcc version 4.8.1, the colleague is on 4.6.3. I've tried adding -std=c++98 etc options to no avail.
I can get the code to compile by changing to eg
nut(3,std::vector<double>(3))
but not sure if this is right as the code then seg faults.
So two questions,
Is it possible with some options/switches to compile the code as is?
If not any idea how these vectors should be declared and set-up?
The nut(3,3) attempts to use 3 as initializer for the inner std::vector<int>.
However, std::vector has an explicit constructor which is why it doesn't compile. As you have found, explicit constructors have to have the type explicitly written, with nut(3, std::vector<int>(3)).
Some older compilers came with a vector that didn't mark the constructor as explicit which would explain your colleagues' observations.

Problems compiling Boost::Python

I want to use c++ numerical recipes on my python script but I am having some issues compiling some stuff in the Boost Python Libraries. Specificly I want to expose the amoeba function to python. I use Make rather than BJam. This is what I get when I try to compile:
costantinoagnesi#costantino-HP-Pavilion-dv5-Notebook-PC:~/Desktop/Boost Python Test$ make
g++ -I/usr/include/python2.7 -I/usr/include -fPIC -c amoeba_py.C
In file included from /usr/local/include/boost/python/object/make_instance.hpp:10:0,
from /usr/local/include/boost/python/object/make_ptr_instance.hpp:8,
from /usr/local/include/boost/python/to_python_indirect.hpp:11,
from /usr/local/include/boost/python/converter/arg_to_python.hpp:10,
from /usr/local/include/boost/python/call.hpp:15,
from /usr/local/include/boost/python/object_core.hpp:14,
from /usr/local/include/boost/python/args.hpp:25,
from /usr/local/include/boost/python.hpp:11,
from amoeba_py.C:73:
/usr/local/include/boost/python/converter/registered.hpp: In function ‘const boost::python::converter::registration&
boost::python::converter::detail::registry_lookup2(T& (*)()) [with T = double(const NRVec<double>&)]’:
/usr/local/include/boost/python/converter/registered.hpp:94:40: instantiated from ‘const >boost::python::converter::registration& boost::python::converter::detail::registry_lookup1(boost::type<T>) [with T = double (&)(const NRVec<double>&)]’
/usr/local/include/boost/python/converter/registered.hpp:105:23: instantiated from const boost::python::converter::registration& boost::python::converter::detail::registered_base<double (&)(const NRVec<double>&)>::converters’
/usr/local/include/boost/python/converter/arg_from_python.hpp:269:99: instantiated from ‘boost::python::converter::pointer_arg_from_python<T>::pointer_arg_from_python(PyObject*) [with T = double (*)(const NRVec<double>&), PyObject = _object]’
/usr/local/include/boost/python/arg_from_python.hpp:70:18: instantiated from ‘boost::python::arg_from_python<T>::arg_from_python(PyObject*) [with T = double (*)(const NRVec<double>&), PyObject = _object]’
/usr/local/include/boost/preprocessor/iteration/detail/local.hpp:43:1: instantiated from >‘PyObject* boost::python::detail::caller_arity<5u>::impl<F, Policies, Sig>::operator( (PyObject*, PyObject*) [with F = void (*)(NRMat<double>&, NRVec<double>&, double, double (*)(const NRVec<double>&), int&), Policies = boost::python::default_call_policies, Sig = boost::mpl::vector6<void, NRMat<double>&, NRVec<double>&, double, double (*)(const NRVec<double>&), int&>, PyObject = _object]’
/usr/local/include/boost/python/object/py_function.hpp:38:33: instantiated from ‘PyObject* boost::python::objects::caller_py_function_impl<Caller>::operator()(PyObject*, PyObject*) [with Caller = boost::python::detail::caller<void (*)(NRMat<double>&, NRVec<double>&, double, double (*)(const NRVec<double>&), int&), boost::python::default_call_policies, boost::mpl::vector6<void, NRMat<double>&, NRVec<double>&, double, double (*)(const NRVec<double>&), int&> >, PyObject = _object]’ amoeba_py.C:79:1: instantiated from here
/usr/local/include/boost/python/converter/registered.hpp:86:7: error: no matching function >for call to ‘register_shared_ptr1(double (*)(const NRVec<double>&))’
/usr/local/include/boost/python/converter/registered.hpp:86:7: note: candidate is:
/usr/local/include/boost/python/converter/registered.hpp:77:3: note: template<class T> void boost::python::converter::detail::register_shared_ptr1(const volatile T*)
make: *** [amoeba_py.o] Error 1
Can someone help me decipher what this error means and perhaps give me some helpful tip to finish my project. It's worth noting that the classic Boost Python example compiles just fine.
Thank you!
Here's the offending text: (lines 73-79)
#include <boost/python.hpp>
using namespace boost::python;
BOOST_PYTHON_MODULE(amoeba)
{
def("amoeba", NR::amoeba);
}
I suspect you're having a similar problem to the guy who asked this question. Are you passing a function pointer as an argument in your C++ code? If so, you can't do that in Python -- see the answer as to why.
You forgot reference operator. Thus the def is getting parameter type double (*)(const NRVec<double>&) instead of const volatile T* it expects.
Your code ought to look like this:
BOOST_PYTHON_MODULE(amoeba)
{
def("amoeba", &NR::amoeba);
}

what is the reason behind vector's push_back error

I have a simple c++ std::vector and inside it, i am storing threads as shown below. Can you please explain why the line with comment "does not compile" shows error during compilation? And why the line with comment "compiles" work?
#include<thread>
#include<vector>
using namespace std;
void abc() {}
int main()
{
vector<thread> workers;
workers.push_back(thread(abc)); // compiles
thread t(abc);
workers.push_back(t); // does not compile
return 0;
}
UPDATE: i am using g++ 4.4.6 on linux. Below is the error
[jim#cola c++]$ g++ -std=c++0x -pthread -g -Wall t.cpp -o t
In file included from /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/x86_64-redhat-linux/bits/c++allocator.h:34,
from /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/bits/allocator.h:48,
from /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/string:43,
from /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/bits/locale_classes.h:42,
from /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/bits/ios_base.h:43,
from /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ios:43,
from /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:40,
from /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/iostream:40,
from t.cpp:1:
/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/thread: In member function ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Tp*, const _Tp&) [with _Tp = std::thread]’:
/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/bits/stl_vector.h:737: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::thread, _Alloc = std::allocator<std::thread>]’
t.cpp:29: instantiated from here
/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/thread:122: error: deleted function ‘std::thread::thread(const std::thread&)’
/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ext/new_allocator.h:105: error: used here
In file included from /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/vector:69,
from t.cpp:4:
/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/thread: In member function ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, _Args&& ...) [with _Args = const std::thread&, _Tp = std::thread, _Alloc = std::allocator<std::thread>]’:
/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/bits/stl_vector.h:741: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::thread, _Alloc = std::allocator<std::thread>]’
t.cpp:29: instantiated from here
/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/thread:122: error: deleted function ‘std::thread::thread(const std::thread&)’
/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/bits/vector.tcc:314: error: used here
You're getting the error because std::thread is noncopyable, and you're trying to insert a copy of t into the vector.
The only way you could make this work would be to do:
workers.push_back(std::move(t));
However, this would mean that after you do that, t no longer represents a thread (the thread it represented was moved into the vector).
The reason is that std::thread has a move constructor, but doesn't have a copy constructor.
Here is a cleaner and faster solution that requires neither copying nor moving:
workers.emplace_back(abc);
Because std::thread is not copyable, you could move it to vector though:
thread t(abc);
workers.push_back(std::move(t));
Better solution is to store smart pointer in vector:
std::vector<std::shared_ptr<std::thread>> workers;
Because when work with lambda, there is no way to capture a move only type, a workaround is to store a move-only type in std::shared_ptr<std::thread>.

make_shared create std::shared_ptr? gcc 4.6.2

i'm using gcc 4.6.2.
I'm trying to push_back in a vector shared_ptr's.
But gcc gives me everytime an error.
Here my codelines:
std::vector< std::tr1::shared_ptr<Process> > procs;
std::string line;
while (getline(file, line) && line.find(JobMask) != std::string::npos)
{
std::string procName = line.substr(line.find(JobMask) + JobMask.size());
std::vector<Instruction> procInstructions = extractProgram(file);
std::queue<int> procInputs = extractInputs(file);
if (!procInstructions.empty())
procs.push_back(std::make_shared<Process>(Process(procName, procInputs, procInstructions))); //line 51
}
return procs;
The Error my gcc is giving is:
Process.cpp: In static member function 'static std::vector<std::tr1::shared_ptr<RMMIX::Process> > RMMIX::Process::createProcesses(const string&)':
Process.cpp:51:95: error: no matching function for call to 'std::vector<std::tr1::shared_ptr<RMMIX::Process> >::push_back(std::shared_ptr<RMMIX::Process>)'
Process.cpp:51:95: note: candidates are:
/usr/lib/gcc/x86_64-pc-linux-gnu/4.6.2/include/g++-v4/bits/stl_vector.h:826:7: note: void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = std::tr1::shared_ptr<RMMIX::Process>, _Alloc = std::allocator<std::tr1::shared_ptr<RMMIX::Process> >, std::vector<_Tp, _Alloc>::value_type = std::tr1::shared_ptr<RMMIX::Process>]
/usr/lib/gcc/x86_64-pc-linux-gnu/4.6.2/include/g++-v4/bits/stl_vector.h:826:7: note: no known conversion for argument 1 from 'std::shared_ptr<RMMIX::Process>' to 'const value_type& {aka const std::tr1::shared_ptr<RMMIX::Process>&}'
/usr/lib/gcc/x86_64-pc-linux-gnu/4.6.2/include/g++-v4/bits/stl_vector.h:839:7: note: void std::vector<_Tp, _Alloc>::push_back(std::vector<_Tp, _Alloc>::value_type&&) [with _Tp = std::tr1::shared_ptr<RMMIX::Process>, _Alloc = std::allocator<std::tr1::shared_ptr<RMMIX::Process> >, std::vector<_Tp, _Alloc>::value_type = std::tr1::shared_ptr<RMMIX::Process>]
/usr/lib/gcc/x86_64-pc-linux-gnu/4.6.2/include/g++-v4/bits/stl_vector.h:839:7: note: no known conversion for argument 1 from 'std::shared_ptr<RMMIX::Process>' to 'std::vector<std::tr1::shared_ptr<RMMIX::Process> >::value_type&& {aka std::tr1::shared_ptr<RMMIX::Process>&&}'
In my eyes the error say's, that std::make_shared create a std::shared_ptr.
But in gcc shared_ptr is in the namespace std::tr1.
How could i fix it?
If I understand correctly, make_shared is new in C++11 and is in namespace std, but it is only available if you compile with -std=gnu++0x or similar. But if you do that, then shared_ptr is also in std.
The problem is that there is another version of shared_ptr in std::tr1, but in C++11 mode you should not use it: it should be considered deprecated.
Your solution is simply to remove every use of tr1 and use the full C++11 version of these classes.
C++ template error message can be a beast to read. But the answer is in the 2nd note.
no known conversion for argument 1 from 'std::shared_ptr<RMMIX::Process>' to 'const value_type& {aka const std::tr1::shared_ptr<RMMIX::Process>&}'
The problem is you're using std::make_shared (which creates a std::shared_ptr) and passing it into a vector of std::tr1::shared_ptr.
The simplest solution is drop the TR1. The stuff from the TR1 was some of first features implemented by compilers when adding C++11 support.
std::vector< std::shared_ptr<Process> > procs;
If you are unable to stop using std::tr1::shared_ptr. You'll have to forgo using make_shared as it was not part of the TR1.