id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
12732	Karma problem converting a char vector to string	Braden McDaniel <braden@…>	Joel de Guzman	"The version of Boost.Spirit.Karma included with Boost 1.63.0 appears to have a problem converting a char vector to a string when building with Apple Clang 8.0 using the `-std=c++14` (or `-std=gnu++14`) option. Consider the following example: 

{{{#!c++
#include <boost/spirit/include/karma.hpp>
#include <boost/fusion/include/adapt_struct.hpp>

struct foo { 
  std::string a, b; 
}; 

BOOST_FUSION_ADAPT_STRUCT( 
  foo, 
  (std::string, a) 
  (std::string, b) 
) 

int main() 
{ 
  using namespace boost::spirit::karma; 

  typedef rule<std::back_insert_iterator<std::string>, foo(), space_type> 
    rule_t; 

  rule_t r 
    =   +char_ << '(' << string << ')' 
    |   skip[string] << string 
    ; 

  foo f = {""a"", ""b""}; 
  std::string s; 
  generate_delimited(std::back_inserter(s), r, space, f); 
} 
}}}

When compiled with the -std=c++14 and -stdlib=libc++ options, the following errors are emitted: 
{{{
$ c++ -I ~/Build/ng-core-Debug/API/inc -std=c++14 -stdlib=libc++ -o karma-char-seq karma-char-seq.cpp
In file included from karma-char-seq.cpp:1:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/phoenix.hpp:11:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/phoenix/phoenix.hpp:11:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/phoenix/core.hpp:13:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/phoenix/core/debug.hpp:17:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/proto/proto.hpp:12:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/proto/core.hpp:21:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/proto/fusion.hpp:22:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/fusion/include/intrinsic.hpp:11:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/fusion/sequence/intrinsic.hpp:23:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/fusion/sequence/intrinsic/swap.hpp:15:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/fusion/view/zip_view.hpp:12:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/fusion/view/zip_view/zip_view.hpp:16:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/fusion/view/zip_view/detail/begin_impl.hpp:14:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/fusion/algorithm/transformation/transform.hpp:11:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/fusion/view/transform_view/transform_view.hpp:22:
In file included from /Users/mcdanb/Build/ng-core-Debug/API/inc/boost/fusion/container/vector/vector10.hpp:25:
/Users/mcdanb/Build/ng-core-Debug/API/inc/boost/fusion/container/vector/vector.hpp:168:19: error: 
      no matching constructor for initialization of 'std::__1::vector<char,
      std::__1::allocator<char> >'
                : elem(std::forward<U>(rhs))
                  ^    ~~~~~~~~~~~~~~~~~~~~
/Users/mcdanb/Build/ng-core-Debug/API/inc/boost/fusion/container/vector/vector.hpp:208:19: note: 
      in instantiation of function template specialization
      'boost::fusion::vector_detail::store<0, std::__1::vector<char,
      std::__1::allocator<char> > >::store<std::__1::basic_string<char> &,
      void>' requested here
                : store<I, T>(forward_at_c<I>(std::forward<Sequence>(rhs)))...
                  ^
/Users/mcdanb/Build/ng-core-Debug/API/inc/boost/fusion/container/vector/vector.hpp:319:15: note: 
      in instantiation of function template specialization
      'boost::fusion::vector_detail::vector_data<boost::fusion::detail::index_sequence<0,
      1>, std::__1::vector<char, std::__1::allocator<char> >,
      std::__1::basic_string<char> >::vector_data<foo, foo, void>' requested
      here
            : base(vector_detail::each_elem(), std::forward<Sequence>(seq))
              ^
/Users/mcdanb/Build/ng-core-Debug/API/inc/boost/type_traits/is_convertible.hpp:482:56: note: 
      in instantiation of function template specialization
      'boost::fusion::vector<std::__1::vector<char, std::__1::allocator<char> >,
      std::__1::basic_string<char> >::vector<foo, foo, void>' requested here
struct is_convertible : public integral_constant<bool, BOOST_IS_CONVERTI...
                                                       ^
/Users/mcdanb/Build/ng-core-Debug/API/inc/boost/type_traits/intrinsics.hpp:214:63: note: 
      expanded from macro 'BOOST_IS_CONVERTIBLE'
#     define BOOST_IS_CONVERTIBLE(T,U) __is_convertible_to(T,U)
                                                              ^
/Users/mcdanb/Build/ng-core-Debug/API/inc/boost/spirit/home/support/attributes.hpp:309:13: note: 
      in instantiation of template class 'boost::is_convertible<foo,
      boost::fusion::vector<std::__1::vector<char, std::__1::allocator<char> >,
      std::__1::basic_string<char> > >' requested here
          : is_convertible<Attribute, Expected>
            ^
/Users/mcdanb/Build/ng-core-Debug/API/inc/boost/mpl/aux_/nested_type_wknd.hpp:27:7: note: 
      in instantiation of template class
      'boost::spirit::traits::detail::attribute_is_compatible<boost::fusion::vector<std::__1::vector<char,
      std::__1::allocator<char> >, std::__1::basic_string<char> >, foo>'
      requested here
    : T::type
      ^
/Users/mcdanb/Build/ng-core-Debug/API/inc/boost/mpl/aux_/preprocessed/gcc/or.hpp:51:11: note: 
      (skipping 12 contexts in backtrace; use -ftemplate-backtrace-limit=0 to
      see all)
          BOOST_MPL_AUX_NESTED_TYPE_WKND(T1)::value
          ^
/Users/mcdanb/Build/ng-core-Debug/API/inc/boost/mpl/aux_/nested_type_wknd.hpp:38:24: note: 
      expanded from macro 'BOOST_MPL_AUX_NESTED_TYPE_WKND'
    ::boost::mpl::aux::nested_type_wknd<T> \
                       ^
/Users/mcdanb/Build/ng-core-Debug/API/inc/boost/function/function_template.hpp:1072:5: note: 
      in instantiation of function template specialization
      'boost::function3<bool,
      boost::spirit::karma::detail::output_iterator<std::__1::back_insert_iterator<std::__1::basic_string<char>
      >, mpl_::int_<15>, boost::spirit::unused_type> &,
      boost::spirit::context<boost::fusion::cons<const foo &,
      boost::fusion::nil_>, boost::fusion::vector<> > &, const
      boost::spirit::karma::any_space<boost::spirit::char_encoding::standard>
      &>::function3<boost::spirit::karma::detail::generator_binder<boost::spirit::karma::alternative<boost::fusion::cons<boost::spirit::karma::sequence<boost::fusion::cons<boost::spirit::karma::plus<boost::spirit::karma::any_char<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type> >,
      boost::fusion::cons<boost::spirit::karma::literal_char<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type, true>,
      boost::fusion::cons<boost::spirit::karma::any_string<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type>,
      boost::fusion::cons<boost::spirit::karma::literal_char<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type, true>, boost::fusion::nil_> > > > >,
      boost::fusion::cons<boost::spirit::karma::sequence<boost::fusion::cons<boost::spirit::karma::omit_directive<boost::spirit::karma::any_string<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type>, false>,
      boost::fusion::cons<boost::spirit::karma::any_string<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type>, boost::fusion::nil_> > >,
      boost::fusion::nil_> > >, mpl_::bool_<false> > >' requested here
    base_type(f)
    ^
/Users/mcdanb/Build/ng-core-Debug/API/inc/boost/function/function_template.hpp:1125:5: note: 
      in instantiation of function template specialization 'boost::function<bool
      (boost::spirit::karma::detail::output_iterator<std::__1::back_insert_iterator<std::__1::basic_string<char>
      >, mpl_::int_<15>, boost::spirit::unused_type> &,
      boost::spirit::context<boost::fusion::cons<const foo &,
      boost::fusion::nil_>, boost::fusion::vector<> > &, const
      boost::spirit::karma::any_space<boost::spirit::char_encoding::standard>
      &)>::function<boost::spirit::karma::detail::generator_binder<boost::spirit::karma::alternative<boost::fusion::cons<boost::spirit::karma::sequence<boost::fusion::cons<boost::spirit::karma::plus<boost::spirit::karma::any_char<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type> >,
      boost::fusion::cons<boost::spirit::karma::literal_char<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type, true>,
      boost::fusion::cons<boost::spirit::karma::any_string<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type>,
      boost::fusion::cons<boost::spirit::karma::literal_char<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type, true>, boost::fusion::nil_> > > > >,
      boost::fusion::cons<boost::spirit::karma::sequence<boost::fusion::cons<boost::spirit::karma::omit_directive<boost::spirit::karma::any_string<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type>, false>,
      boost::fusion::cons<boost::spirit::karma::any_string<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type>, boost::fusion::nil_> > >,
      boost::fusion::nil_> > >, mpl_::bool_<false> > >' requested here
    self_type(f).swap(*this);
    ^
/Users/mcdanb/Build/ng-core-Debug/API/inc/boost/spirit/home/karma/nonterminal/rule.hpp:192:19: note: 
      in instantiation of function template specialization 'boost::function<bool
      (boost::spirit::karma::detail::output_iterator<std::__1::back_insert_iterator<std::__1::basic_string<char>
      >, mpl_::int_<15>, boost::spirit::unused_type> &,
      boost::spirit::context<boost::fusion::cons<const foo &,
      boost::fusion::nil_>, boost::fusion::vector<> > &, const
      boost::spirit::karma::any_space<boost::spirit::char_encoding::standard>
      &)>::operator=<boost::spirit::karma::detail::generator_binder<boost::spirit::karma::alternative<boost::fusion::cons<boost::spirit::karma::sequence<boost::fusion::cons<boost::spirit::karma::plus<boost::spirit::karma::any_char<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type> >,
      boost::fusion::cons<boost::spirit::karma::literal_char<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type, true>,
      boost::fusion::cons<boost::spirit::karma::any_string<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type>,
      boost::fusion::cons<boost::spirit::karma::literal_char<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type, true>, boost::fusion::nil_> > > > >,
      boost::fusion::cons<boost::spirit::karma::sequence<boost::fusion::cons<boost::spirit::karma::omit_directive<boost::spirit::karma::any_string<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type>, false>,
      boost::fusion::cons<boost::spirit::karma::any_string<boost::spirit::char_encoding::standard,
      boost::spirit::unused_type>, boost::fusion::nil_> > >,
      boost::fusion::nil_> > >, mpl_::bool_<false> > >' requested here
            lhs.f = detail::bind_generator<Auto>(
                  ^
/Users/mcdanb/Build/ng-core-Debug/API/inc/boost/spirit/home/karma/nonterminal/rule.hpp:201:13: note: 
      in instantiation of function template specialization
      'boost::spirit::karma::rule<std::__1::back_insert_iterator<std::__1::basic_string<char>
      >, foo (),
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal,
      boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space,
      boost::spirit::char_encoding::standard> >, 0>, boost::spirit::unused_type,
      boost::spirit::unused_type>::define<mpl_::bool_<false>,
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::bitwise_or,
      boost::proto::argsns_::list2<const
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_left,
      boost::proto::argsns_::list2<const
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_left,
      boost::proto::argsns_::list2<const
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_left,
      boost::proto::argsns_::list2<const
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::unary_plus,
      boost::proto::argsns_::list1<const
      boost::spirit::terminal<boost::spirit::tag::char_code<boost::spirit::tag::char_,
      boost::spirit::char_encoding::standard> > &>, 1> &,
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal,
      boost::proto::argsns_::term<const char &>, 0> >, 2> &, const
      boost::spirit::terminal<boost::spirit::tag::char_code<boost::spirit::tag::string,
      boost::spirit::char_encoding::standard> > &>, 2> &,
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal,
      boost::proto::argsns_::term<const char &>, 0> >, 2> &, const
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_left,
      boost::proto::argsns_::list2<const
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::subscript,
      boost::proto::argsns_::list2<const
      boost::spirit::terminal<boost::spirit::tag::skip> &, const
      boost::spirit::terminal<boost::spirit::tag::char_code<boost::spirit::tag::string,
      boost::spirit::char_encoding::standard> > &>, 2> &, const
      boost::spirit::terminal<boost::spirit::tag::char_code<boost::spirit::tag::string,
      boost::spirit::char_encoding::standard> > &>, 2> &>, 2> >' requested here
            define<mpl::false_>(*this, expr, traits::matches<karma::doma...
            ^
karma-char-seq.cpp:24:13: note: in instantiation of function template
      specialization
      'boost::spirit::karma::rule<std::__1::back_insert_iterator<std::__1::basic_string<char>
      >, foo (),
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal,
      boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space,
      boost::spirit::char_encoding::standard> >, 0>, boost::spirit::unused_type,
      boost::spirit::unused_type>::rule<boost::proto::exprns_::expr<boost::proto::tagns_::tag::bitwise_or,
      boost::proto::argsns_::list2<const
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_left,
      boost::proto::argsns_::list2<const
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_left,
      boost::proto::argsns_::list2<const
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_left,
      boost::proto::argsns_::list2<const
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::unary_plus,
      boost::proto::argsns_::list1<const
      boost::spirit::terminal<boost::spirit::tag::char_code<boost::spirit::tag::char_,
      boost::spirit::char_encoding::standard> > &>, 1> &,
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal,
      boost::proto::argsns_::term<const char &>, 0> >, 2> &, const
      boost::spirit::terminal<boost::spirit::tag::char_code<boost::spirit::tag::string,
      boost::spirit::char_encoding::standard> > &>, 2> &,
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal,
      boost::proto::argsns_::term<const char &>, 0> >, 2> &, const
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::shift_left,
      boost::proto::argsns_::list2<const
      boost::proto::exprns_::expr<boost::proto::tagns_::tag::subscript,
      boost::proto::argsns_::list2<const
      boost::spirit::terminal<boost::spirit::tag::skip> &, const
      boost::spirit::terminal<boost::spirit::tag::char_code<boost::spirit::tag::string,
      boost::spirit::char_encoding::standard> > &>, 2> &, const
      boost::spirit::terminal<boost::spirit::tag::char_code<boost::spirit::tag::string,
      boost::spirit::char_encoding::standard> > &>, 2> &>, 2> >' requested here
        =   +char_ << '(' << string << ')'
            ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:489:40: note: 
      candidate constructor not viable: no known conversion from
      'std::__1::basic_string<char>' to 'const allocator_type' (aka 'const
      std::__1::allocator<char>') for 1st argument
    _LIBCPP_INLINE_VISIBILITY explicit vector(const allocator_type& __a)
                                       ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:501:14: note: 
      candidate constructor not viable: no known conversion from
      'std::__1::basic_string<char>' to 'size_type' (aka 'unsigned long') for
      1st argument
    explicit vector(size_type __n);
             ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:537:5: note: 
      candidate constructor not viable: no known conversion from
      'std::__1::basic_string<char>' to 'initializer_list<value_type>' (aka
      'initializer_list<char>') for 1st argument
    vector(initializer_list<value_type> __il);
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:549:5: note: 
      candidate constructor not viable: no known conversion from
      'std::__1::basic_string<char>' to 'const std::__1::vector<char,
      std::__1::allocator<char> >' for 1st argument
    vector(const vector& __x);
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:555:5: note: 
      candidate constructor not viable: no known conversion from
      'std::__1::basic_string<char>' to 'std::__1::vector<char,
      std::__1::allocator<char> >' for 1st argument
    vector(vector&& __x)
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:508:9: note: 
      candidate constructor template not viable: requires 2 arguments, but 1 was
      provided
        vector(_InputIterator __first,
        ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:516:9: note: 
      candidate constructor template not viable: requires at least 3 arguments,
      but 1 was provided
        vector(_InputIterator __first, _InputIterator __last, const allo...
        ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:523:9: note: 
      candidate constructor template not viable: requires 2 arguments, but 1 was
      provided
        vector(_ForwardIterator __first,
        ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:530:9: note: 
      candidate constructor template not viable: requires at least 3 arguments,
      but 1 was provided
        vector(_ForwardIterator __first, _ForwardIterator __last, const ...
        ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:483:5: note: 
      candidate constructor not viable: requires 0 arguments, but 1 was provided
    vector() _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:503:14: note: 
      candidate constructor not viable: requires 2 arguments, but 1 was provided
    explicit vector(size_type __n, const allocator_type& __a);
             ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:505:5: note: 
      candidate constructor not viable: requires 2 arguments, but 1 was provided
    vector(size_type __n, const_reference __x);
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:539:5: note: 
      candidate constructor not viable: requires 2 arguments, but 1 was provided
    vector(initializer_list<value_type> __il, const allocator_type& __a);
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:550:5: note: 
      candidate constructor not viable: requires 2 arguments, but 1 was provided
    vector(const vector& __x, const allocator_type& __a);
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:562:5: note: 
      candidate constructor not viable: requires 2 arguments, but 1 was provided
    vector(vector&& __x, const allocator_type& __a);
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:506:5: note: 
      candidate constructor not viable: requires 3 arguments, but 1 was provided
    vector(size_type __n, const_reference __x, const allocator_type& __a);
    ^
1 error generated.
}}}

The problem construct appears to be `+char_`. The error goes away if it is replaced with `string`; but the error also goes away if the alternative is removed from the rule. 

This code worked fine with the Boost.Spirit.Karma included with Boost 1.62.0."	Bugs	new	To Be Determined	fusion	Boost 1.64.0	Regression