compatibility with prettyprint

[nevion]

fmt used to work/integrate well with https://github.com/louisdx/cxx-prettyprint , however I do not find that to be the case since 5.0, outputting something like a std::list of data no longer works.

Reproducing program:

#include <list>

#include <fmt/format.h>
#include <prettyprint.hpp>

int main( int argc, char **argv ) {

  std::list<int> container;

  for( size_t i = 0; i < 10; ++i){
    container.push_back( (int) i );
  }
  fmt::print("container = {}", container);

  return 0;
}

Errors compiling with gcc 5.4:

In file included from external/fmt/include/fmt/format.h:54:0,
from fmttest/main.cpp:4:
external/fmt/include/fmt/core.h: In instantiation of 'static void fmt::v5::internal::value::format_custom_arg(const void*, Context&) [with T = std::__cxx11::list; Context = fmt::v5::basic_format_context<std::back_insert_iterator<fmt::v5::internal::basic_buffer >, char>]':
external/fmt/include/fmt/core.h:563:19: required from 'fmt::v5::internal::value::value(const T&) [with T = std::__cxx11::list; Context = fmt::v5::basic_format_context<std::back_insert_iterator<fmt::v5::internal::basic_buffer >, char>]'
external/fmt/include/fmt/core.h:591:76: required from 'fmt::v5::internal::init<Context, T, TYPE>::operator fmt::v5::internal::value() const [with Context = fmt::v5::basic_format_context<std::back_insert_iterator<fmt::v5::internal::basic_buffer >, char>; T = const std::__cxx11::list&; fmt::v5::internal::type TYPE = (fmt::v5::internal::type)13u]'
external/fmt/include/fmt/core.h:995:35: required from 'typename std::enable_if<IS_PACKED, fmt::v5::internal::value >::type fmt::v5::internal::make_arg(const T&) [with bool IS_PACKED = true; Context = fmt::v5::basic_format_context<std::back_insert_iterator<fmt::v5::internal::basic_buffer >, char>; T = std::__cxx11::list; typename std::enable_if<IS_PACKED, fmt::v5::internal::value >::type = fmt::v5::internal::value<fmt::v5::basic_format_context<std::back_insert_iterator<fmt::v5::internal::basic_buffer >, char> >]'
external/fmt/include/fmt/core.h:1053:51: required from 'fmt::v5::format_arg_store<Context, Args>::format_arg_store(const Args& ...) [with Context = fmt::v5::basic_format_context<std::back_insert_iterator<fmt::v5::internal::basic_buffer >, char>; Args = {std::__cxx11::list<int, std::allocator >}]'
external/fmt/include/fmt/core.h:1431:55: required from 'void fmt::v5::print(fmt::v5::string_view, const Args& ...) [with Args = {std::__cxx11::list<int, std::allocator >}; fmt::v5::string_view = fmt::v5::basic_string_view]'
fmttest/main.cpp:14:41: required from here
external/fmt/include/fmt/core.h:577:56: error: 'fmt::v5::basic_format_context<std::back_insert_iterator<fmt::v5::internal::basic_buffer >, char>::formatter_type<std::__cxx11::list >::type f' has incomplete type
typename Context::template formatter_type::type f;

[foonathan]

You need to include <fmt/ostream.h>.