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boostorg / pfr

std::tuple like methods for user defined types without any macro or boilerplate code
https://boost.org/libs/pfr
Boost Software License 1.0
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Support std::optional<> #39

Closed filcuc closed 4 years ago

filcuc commented 5 years ago

It seems that std::experimental::optional (c++14) or std::optional(c++17) are not supported

n file included from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/detail/core14_loophole.hpp:29:0,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/detail/core14.hpp:13,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/precise/core.hpp:24,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/precise.hpp:12,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr.hpp:12,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/LibVimarIPCParser/BaseValueHandlers.h:6,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/LibVimarIPCParser/StdValueHandlers.h:4,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/LibVimarIPCParser/UserParser.h:4,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/LibVimarIPCParser/SystemFunctionParser.h:10,
                 from /home/cucchetf/workspace/p378_ipconnectorserver/src/ipc/SFClientIPC.h:5,
                 from /home/cucchetf/workspace/p378_ipconnectorserver/src/ipc/SFClientIPC.cpp:1:
/opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/detail/offset_based_getter.hpp: In instantiation of ‘class boost::pfr::detail::offset_based_getter<ipconnector::Temp, boost::pfr::detail::sequence_tuple::tuple<int, int> >’:
/opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/detail/core14_loophole.hpp:154:61:   required from ‘auto boost::pfr::detail::tie_as_tuple_loophole_impl(T&) [with T = ipconnector::Temp]’
/opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/detail/core14_loophole.hpp:255:55:   required from ‘void boost::pfr::detail::for_each_field_dispatcher(T&, F&&, std::index_sequence<I ...>) [with T = ipconnector::Temp; F = boost::pfr::for_each_field(T&&, F&&) [with T = ipconnector::Temp&; F = ipconnector::SFClientIPC::ModifyScene(const VimarIPCParser::SystemFunctionParser::ModifySceneRequest&)::<lambda(const auto:9&)>]::<lambda(auto:1&&)>; unsigned int ...I = {0u, 1u}; std::index_sequence<I ...> = std::integer_sequence<unsigned int, 0u, 1u>]’
/opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/precise/core.hpp:140:52:   required from ‘void boost::pfr::for_each_field(T&&, F&&) [with T = ipconnector::Temp&; F = ipconnector::SFClientIPC::ModifyScene(const VimarIPCParser::SystemFunctionParser::ModifySceneRequest&)::<lambda(const auto:9&)>]’
/home/cucchetf/workspace/p378_ipconnectorserver/src/ipc/SFClientIPC.cpp:117:56:   required from here
/opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/detail/offset_based_getter.hpp:63:3: error: static assertion failed: ====================> Boost.PFR: Member sequence does not indicate correct size for struct type!
   static_assert(sizeof(U) == sizeof(S), "====================> Boost.PFR: Member sequence does not indicate correct size for struct type!");
   ^~~~~~~~~~~~~
In file included from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/detail/core14.hpp:13:0,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/precise/core.hpp:24,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/precise.hpp:12,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr.hpp:12,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/LibVimarIPCParser/BaseValueHandlers.h:6,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/LibVimarIPCParser/StdValueHandlers.h:4,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/LibVimarIPCParser/UserParser.h:4,
                 from /opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/LibVimarIPCParser/SystemFunctionParser.h:10,
                 from /home/cucchetf/workspace/p378_ipconnectorserver/src/ipc/SFClientIPC.h:5,
                 from /home/cucchetf/workspace/p378_ipconnectorserver/src/ipc/SFClientIPC.cpp:1:
/opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/detail/core14_loophole.hpp: In instantiation of ‘void boost::pfr::detail::for_each_field_dispatcher(T&, F&&, std::index_sequence<I ...>) [with T = ipconnector::Temp; F = boost::pfr::for_each_field(T&&, F&&) [with T = ipconnector::Temp&; F = ipconnector::SFClientIPC::ModifyScene(const VimarIPCParser::SystemFunctionParser::ModifySceneRequest&)::<lambda(const auto:9&)>]::<lambda(auto:1&&)>; unsigned int ...I = {0u, 1u}; std::index_sequence<I ...> = std::integer_sequence<unsigned int, 0u, 1u>]’:
/opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/precise/core.hpp:140:52:   required from ‘void boost::pfr::for_each_field(T&&, F&&) [with T = ipconnector::Temp&; F = ipconnector::SFClientIPC::ModifyScene(const VimarIPCParser::SystemFunctionParser::ModifySceneRequest&)::<lambda(const auto:9&)>]’
/home/cucchetf/workspace/p378_ipconnectorserver/src/ipc/SFClientIPC.cpp:117:56:   required from here
/opt/vrag/releases/private/cucchetf-vimar-agx-dbg-latest/sdk/sysroots/cortexa9hf-neon-poky-linux-gnueabi/usr/include/boost/pfr/detail/core14_loophole.hpp:254:23: error: use of ‘boost::pfr::for_each_field(T&&, F&&)::<lambda(auto:1&&)> mutable [with auto:1 = boost::pfr::detail::sequence_tuple::tuple<int&, int&>; T = ipconnector::Temp&; F = ipconnector::SFClientIPC::ModifyScene(const VimarIPCParser::SystemFunctionParser::ModifySceneRequest&)::<lambda(const auto:9&)>]’ before deduction of ‘auto’
     std::forward<F>(f)(
     ~~~~~~~~~~~~~~~~~~^
         boost::pfr::detail::tie_as_tuple_loophole_impl(t)
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     );
     ~
filcuc commented 5 years ago

arm-poky-linux-gnueabi-g++ (GCC) 6.3.0 Copyright (C) 2016 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

filcuc commented 5 years ago 
#include <iostream>
#include <boost/pfr.hpp>
#include <experimental/optional>

struct Test {
  std::experimental::optional<int> value;
};

int main() {
  Test test;
  boost::pfr::for_each_field(test, [](const auto& v) {});
  return 0;
}
Stannieman commented 4 years ago

Instead of supporting std::optional specifically, would it be possible to enable a more generic extension of the serialization mechanism?

For example we can register a function to handle some specific type (optional, vector, ...) which returns a string, and then if a field of such type is encountered it will call that function instead of failing.

apolukhin commented 4 years ago

Instead of supporting std::optional specifically, would it be possible to enable a more generic extension of the serialization mechanism?

Unfortunately that won't help with the optional case case.

apolukhin commented 4 years ago

The only way to deal with the issue is to upgrade to the C++17 standard.

I've described the limitations of C++14 more precisely in the docs: http://apolukhin.github.io/magic_get/boost_pfr/limitations.html

Alas, that's the only known solution to the problem.