Code:
In file included from /tmp/gcc-explorer-compiler1141115-14326-85vjpc/example.cpp:1:
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/vector:60:
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/stl_algobase.h:71:
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/predefined_ops.h:191:17: error: invalid operands to binary expression ('std::vector<int, std::allocator<int> >' and 'int')
{ return *__it == _M_value; }
~~~~~ ^ ~~~~~~~~
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/stl_algo.h:120:8: note: in instantiation of function template specialization '__gnu_cxx::__ops::_Iter_equals_val<const int>::operator()<__gnu_cxx::__normal_iterator<std::vector<int, std::allocator<int> > *, std::vector<std::vector<int, std::allocator<int> >, std::allocator<std::vector<int, std::allocator<int> > > > > >' requested here
if (__pred(__first))
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/stl_algo.h:161:14: note: in instantiation of function template specialization 'std::__find_if<__gnu_cxx::__normal_iterator<std::vector<int, std::allocator<int> > *, std::vector<std::vector<int, std::allocator<int> >, std::allocator<std::vector<int, std::allocator<int> > > > >, __gnu_cxx::__ops::_Iter_equals_val<const int> >' requested here
return __find_if(__first, __last, __pred,
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/stl_algo.h:3778:19: note: in instantiation of function template specialization 'std::__find_if<__gnu_cxx::__normal_iterator<std::vector<int, std::allocator<int> > *, std::vector<std::vector<int, std::allocator<int> >, std::allocator<std::vector<int, std::allocator<int> > > > >, __gnu_cxx::__ops::_Iter_equals_val<const int> >' requested here
return std::__find_if(__first, __last,
^
7 : note: in instantiation of function template specialization 'std::find<__gnu_cxx::__normal_iterator > *, std::vector >, std::allocator > > > >, int>' requested here
std::vector< std::vector <int> >::const_iterator it = std::find( v.begin(), v.end(), a );
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/stl_pair.h:214:5: note: candidate template ignored: could not match 'pair' against 'vector'
operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/stl_iterator.h:292:5: note: candidate template ignored: could not match 'reverse_iterator' against 'vector'
operator==(const reverse_iterator<_Iterator>& __x,
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/stl_iterator.h:342:5: note: candidate template ignored: could not match 'reverse_iterator' against 'vector'
operator==(const reverse_iterator<_IteratorL>& __x,
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/stl_iterator.h:808:5: note: candidate template ignored: could not match '__normal_iterator' against 'vector'
operator==(const __normal_iterator<_IteratorL, _Container>& __lhs,
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/stl_iterator.h:815:5: note: candidate template ignored: could not match '__normal_iterator' against 'vector'
operator==(const __normal_iterator<_Iterator, _Container>& __lhs,
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/stl_iterator.h:1048:5: note: candidate template ignored: could not match 'move_iterator' against 'vector'
operator==(const move_iterator<_IteratorL>& __x,
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/stl_iterator.h:1054:5: note: candidate template ignored: could not match 'move_iterator' against 'vector'
operator==(const move_iterator<_Iterator>& __x,
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/ext/new_allocator.h:139:5: note: candidate template ignored: could not match 'new_allocator' against 'vector'
operator==(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/allocator.h:128:5: note: candidate template ignored: could not match 'allocator' against 'vector'
operator==(const allocator<_T1>&, const allocator<_T2>&)
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/allocator.h:133:5: note: candidate template ignored: could not match 'allocator' against 'vector'
operator==(const allocator<_Tp>&, const allocator<_Tp>&)
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/stl_vector.h:1511:5: note: candidate template ignored: could not match 'vector<type-parameter-0-0, type-parameter-0-1>' against 'const int'
operator==(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/postypes.h:216:5: note: candidate template ignored: could not match 'fpos' against 'vector'
operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/basic_string.h:2505:5: note: candidate template ignored: could not match 'basic_string' against 'vector'
operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/basic_string.h:2512:5: note: candidate template ignored: could not match 'basic_string' against 'vector'
operator==(const basic_string<_CharT>& __lhs,
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/basic_string.h:2526:5: note: candidate template ignored: could not match 'const _CharT *' against 'std::vector<int, std::allocator<int> >'
operator==(const _CharT* __lhs,
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/basic_string.h:2538:5: note: candidate template ignored: could not match 'basic_string' against 'vector'
operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
^
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/random.tcc:2030:5: note: candidate template ignored: could not match 'normal_distribution' against 'vector'
operator==(const std::normal_distribution<_RealType>& __d1,
^
1 error generated.
Compilation failed
C'est pas cryptique, il te dit clairement qu'il ne trouve pas d'opérateur == qui prend un vector<int> et un int.