Linking error "duplicate symbol: std::type_info::operator==" on static build with MinGW

[o-kos]

json 3.9.1 + MinGW 10.3.0 + Clang 12.0.0 x86
Link error on build test example with "--static" flag when use dump() method:

warning: failed to compute relocation: IMAGE_REL_I386_REL32, Invalid data was encountered while parsing the file
lld-link: error: duplicate symbol: std::type_info::operator==(std::type_info const&) const
>>> defined at C:/tools/msys64/mingw32/include/c++/10.3.0/typeinfo:121
>>>            objects.a(main.cpp.obj)
>>> defined at libstdc++.a(tinfo.o)
clang++: error: linker command failed with exit code 1 (use -v to see invocation)

without the "--static" flag, the build finishes successfully.

Can you provide a small but working code example?

#include "nlohmann/json.hpp"
using json = nlohmann::json;

int main()
{
    json j;
    j["pi"] = 3.141;
    std::string s = j.dump(2);
}

If comment string with j.dump(), build is ok.

[nlohmann]

I am not sure how this issue is related to this library if it mentions a duplicate symbol in namespace std... 🤔

[o-kos]

But this error exists only when using .dump () method and only in static build mode.

[nlohmann]

I understand - but maybe it's just triggering some bug inside the compiler. Anyway, I see if I can reproduce this in the CI.

[o-kos]

I looked inside the json.hpp code and reproduced problem without json library:

#include <memory>

class output_string_adapter
{
public:
    output_string_adapter() = default;
};

int main()
{
    std::make_shared<output_string_adapter>();
}

If last code line don't consist std::make_shared - no error. Do you have anything version about this?

[nlohmann]

Thanks for checking back!

[maveric2]

See the issue too, but cannot reproduce it with the reduced example (without json). I get the error within another context.