Description of problem:


Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1. Create a simple file like

#include <boost/lexical_cast.hpp>
#include <parallel/algorithm>
#include <iostream>
int main(int argc, char **argv) {
   std::cout << "hello, world!" << std::endl;
}

2. Compile it

Actual results:

In file included from /usr/include/c++/6.0.0/tr1/random:46:0,
                 from /usr/include/c++/6.0.0/parallel/random_number.h:36,
                 from /usr/include/c++/6.0.0/parallel/partition.h:38,
                 from /usr/include/c++/6.0.0/parallel/quicksort.h:36,
                 from /usr/include/c++/6.0.0/parallel/sort.h:48,
                 from /usr/include/c++/6.0.0/parallel/algo.h:45,
                 from /usr/include/c++/6.0.0/parallel/algorithm:37,
                 from test.cc:2:
/usr/include/c++/6.0.0/tr1/cmath: In function ‘float std::tr1::acosh(float)’:
/usr/include/c++/6.0.0/tr1/cmath:424:18: error: ‘float std::tr1::acosh(float)’ conflicts with a previous declaration
   acosh(float __x)
                  ^
In file included from /usr/include/boost/config/no_tr1/cmath.hpp:21:0,
                 from /usr/include/boost/numeric/conversion/converter_policies.hpp:15,
                 from /usr/include/boost/numeric/conversion/converter.hpp:14,
                 from /usr/include/boost/numeric/conversion/cast.hpp:33,
                 from /usr/include/boost/lexical_cast/detail/converter_numeric.hpp:37,
                 from /usr/include/boost/lexical_cast/try_lexical_convert.hpp:41,
                 from /usr/include/boost/lexical_cast.hpp:32,
                 from test.cc:1:
/usr/include/c++/6.0.0/cmath:1224:3: note: previous declaration ‘constexpr float std::acosh(float)’
   acosh(float __x)
   ^~~~~
etc. etc. etc.

Expected results:

should compile cleanly as it does with gcc-5.3.1-2.fc23.x86_64 on Fedora 23.

Additional info:

Switching the order of the two includes works around the problem.