Compilation "note" on GCC 6 ARM

[pn1k]

When compiling this code:

#include <iostream>
#include <nlohmann/json.hpp>

using json = nlohmann::json;

int main(int argc, char *argv[]) {
  json o=json::parse("{\"foo\":\"bar\",\"list\":{\"100\":{\"l100\":100},\"200\":{\"l200\":200}}}") ;

  json& l=o["list"];

  for (json::iterator it = l.begin(); it != l.end(); ++it) {
    std::cout << it.key() << " : " << it.value() << "\n";
  }

}

compiler report "note":

In file included from /usr/include/c++/6/map:60:0,
                 from /usr/local/include/nlohmann/json.hpp:50,
                 from test.cpp:2:
/usr/include/c++/6/bits/stl_tree.h: In member function ‘std::pair<std::_Rb_tree_node_base*, std::_Rb_tree_node_base*> std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_get_insert_hint_unique_pos(std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::const_iterator, const key_type&) [with _Key = std::__cxx11::basic_string<char>; _Val = std::pair<const std::__cxx11::basic_string<char>, nlohmann::basic_json<> >; _KeyOfValue = std::_Select1st<std::pair<const std::__cxx11::basic_string<char>, nlohmann::basic_json<> > >; _Compare = std::less<std::__cxx11::basic_string<char> >; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, nlohmann::basic_json<> > >]’:
/usr/include/c++/6/bits/stl_tree.h:1928:5: note: parameter passing for argument of type ‘std::_Rb_tree<std::__cxx11::basic_string<char>, std::pair<const std::__cxx11::basic_string<char>, nlohmann::basic_json<> >, std::_Select1st<std::pair<const std::__cxx11::basic_string<char>, nlohmann::basic_json<> > >, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, nlohmann::basic_json<> > > >::const_iterator {aka std::_Rb_tree_const_iterator<std::pair<const std::__cxx11::basic_string<char>, nlohmann::basic_json<> > >}’ will change in GCC 7.1
     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[nlohmann]

Thanks for reporting. I'm not sure whether this is an issue: we already use GCC 7.1 on Travis, and locally I compile and test with GCC 8.

[pn1k]

This "note" happens only on arm-linux-gnueabihf arch (Raspberry Pi) . On the same version of GCC 6 (6.3.0) on x86-64 arch the test code compiles well without any notes. However, compiled code works well on ARM.

This note can be turned off by passing argument '-Wno-psabi' to compiler.

[ghost]

still broken

[ghost]

same thing on 8.1

[jaredgrubb]

The "note: parameter passing for argument of type ... will change in GCC 7.1" is an internal note about internal data types to the STL and doesn't seem to have anything to do with nlohmann json.

Maybe you are mixing versions of libstdc++ and GCC that are not meant to be used together? I would check how your compiler is finding your STL. If you are making your own GCC, maybe you forgot to also build a compatible version of libstdc++ and you're getting a system one or seomthing?

[ghost]

no, actually i tell you what it is, when not having enough memory, compiler front end chocks on, for example parsing a map with universal initialization it's all ok, once i figured it out

…

On Sun, Feb 17, 2019 at 10:40 AM Jared Grubb ***@***.***> wrote: The "note: parameter passing for argument of type ... will change in GCC 7.1" is an internal note about internal data types to the STL and doesn't seem to have anything to do with nlohmann json. Maybe you are mixing versions of libstdc++ and GCC that are not meant to be used together? I would check how your compiler is finding your STL. If you are making your own GCC, maybe you forgot to also build a compatible version of libstdc++ and you're getting a system one or seomthing? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#658 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/Alm61e2jmSD1w8YwC_dhfLn1VnDPBAsQks5vOYX_gaJpZM4OZcp6> .