std::chrono conversion does not compile with libc++

[dbahrdt]

Describe the bug

I'm using jsoncons to convert std::chrono::seconds to/from json using clang and libc++.
I'm getting the following compiler error:

include/jsoncons/reflect/json_conv_traits.hpp:1636:54: error: cannot convert 'bigint' (aka 'basic_bigint<allocator<unsigned long>>') to 'long long' without a conversion operator
 1636 |                         return result_type(in_place, static_cast<Rep>(n));

The source is:

                    case semantic_tag::epoch_milli:
                    {
                        auto sv = j.as_string_view();
                        bigint n;
                        auto r = to_bigint(sv.data(), sv.length(), n);
                        if (!r) {return result_type(jsoncons::unexpect, conv_errc::not_epoch);}
                        if (n != 0)
                        {
                            n = n / millis_in_second;
                        }
                        return result_type(in_place, static_cast<Rep>(n));

In lib++ Rep is long long (https://github.com/llvm/llvm-project/blob/804c0345f5dc0fbb5bea5af6486ebdcfc0c99cb4/libcxx/include/chrono#L103).
jsoncons::basic_bigint defines cast operators for int64_t.
However, libc++ defines int64_t to be long.

The error can be fixed for this specific compiler/architecture/stdlib combination by adding a respective cast operator to bigint:

    explicit operator long long() const
    {
      return static_cast<long long>(static_cast<int64_t>(*this));
    }

Since other compilers may declare int64_t to be long long this is not a generic solution.
See https://godbolt.org/z/YvPza36YY for a minimum working example, albeit with a rather old jsoncons version.

What compiler, architecture, and operating system?

• Compiler: clang version 21.1.6
• Architecture: x86_64-pc-linux-gnu
• Operating system: Arch Linux

What jsoncons library version?

1.5.0 via Conan

[danielaparker]

Thanks for reporting this one. We'll look into it.

[danielaparker]

Should be fixed on master.