Can't serialize tuple to msgpack

[marton78]

This tiny self-contained example doesn't compile:

std::tuple<int, std::string> tup{ 42, "foo" };
std::string temp = BitSerializer::SaveObject<BitSerializer::MsgPack::MsgPackArchive>(tup);

Breaks with:

serialization_base_types.h:484:20: error: static assertion failed due to requirement
'!MsgPackWriteRootScope::is_binary || (hasGlobalSize || isEnumerable)':
BitSerializer. Saving to a binary archive requires a known container size.

[marton78]

Maybe this fixed by 1608504? If yes, could you please create a new release and push it to Conan? Thanks!

[marton78]

Maybe it's a different problem than the one described in #7 though, because adding the following doesn't help:

namespace std {
  template <typename... Params>
  constexpr size_t size(std::tuple<Params...>&& t)
  {
    return std::tuple_size(t);
  }
}

[marton78]

Yes, I have tried to build my project with master and can verify that the problem still exists.

Moreover, a warning has been introduced in the recent UTF related changes.:

conversion_detail/convert_utf.h:805:17: error: unused function 'DetectEncoding' [-Werror,-Wunused-function]
  805 |         static UtfType DetectEncoding(std::istream& inputStream, bool skipBomWhenFound = true)
      |                        ^~~~~~~~~~~~~~
1 error generated.

I compile with -Werror -Wall -Wextra -pedantic -Wno-unused-parameter

[PavelKisliak]

Maybe it's a different problem than the one described in #7 though, because adding the following doesn't help:

Thanks for reporting the issue, this is a different one.
Your example with std::size() doesn't work due to parameter type, it should be const ref:

namespace std
{
    template<typename ...TArgs>
    constexpr size_t size(const std::tuple<TArgs...>&) noexcept
    {
        return sizeof...(TArgs);
    }
}

As a quick fix, this might work, but not sure is it good idea to bring this fix into the library, code analyzers will not happy with it :).
I need to think about other possible options.

Moreover, a warning has been introduced in the recent UTF related changes.:

conversion_detail/convert_utf.h:805:17: error: unused function 'DetectEncoding' [-Werror,-Wunused-function]
  805 |         static UtfType DetectEncoding(std::istream& inputStream, bool skipBomWhenFound = true)
      |                        ^~~~~~~~~~~~~~
1 error generated.

I compile with -Werror -Wall -Wextra -pedantic -Wno-unused-parameter

This is used in the RapidYaml archive, but this is absolutely valid issue.
I will try to suppress such warnings for different BitSerializer configurations.

[marton78]

Messing with the std namespace is forbidden by the C++ standard, so adding a global size method there isn't a good idea. I have hot-fixed the issue for now by adding two partial specializations to object_traits.h:

template <typename... Args>
struct has_size<std::tuple<Args...>> : std::true_type {};

template <typename... Args>
constexpr size_t GetContainerSize(std::tuple<Args...> const&) {
  return sizeof...(Args);
}

[PavelKisliak]

The issue with serialization std::tuple has been fixed, maybe the solution is not the best, but at the moment I have no better ideas.
Is it still important for you to get the new release with this fix ASAP?

[marton78]

Hey @PavelKisliak, thanks for the offer, my workaround mentioned above works fine for now, so thanks, I'm okay for the time being.

[marton78]

@PavelKisliak could you please push 0.80 to https://conan.io/center/recipes/bitserializer ?

[PavelKisliak]

I've already prepared PRs for both Conan ( conan-io/conan-center-index#27355 ) and VCPKG ( microsoft/vcpkg#45342 ).