On MSVC std::filesystem::path cannot be used as Lua type

[zziger]

On Windows compilation fails if std::filesystem::path type is passed to Lua. Similar issue happens when registering custom usertype or customization traits for std::filesystem::path.

Example code

#define SOL_ALL_SAFETIES_ON 1
#include <sol/sol.hpp>

#include <filesystem>
#include <iostream>

namespace sol {
	template <>
	struct is_container<std::filesystem::path> : std::false_type {};

	template <>
	struct is_to_stringable<std::filesystem::path> : std::false_type {};
}

int main(int, char*[]) {
	sol::state lua;
	lua.open_libraries();
	lua["test"] = std::filesystem::path("test");
	lua.script("print(test)");

	std::cout << std::endl;
	return 0;
}

Sol2 v3.3.0
This code does not compile on MSVC (VS 2022, MSVC 19.38.33133), but compiles on Windows with GCC (GCC 11.4.0, MinGW 13.2.0-rt_v11-rev0)

Compilation error message on MSVC

Expand error

C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/stack_core.hpp(897): error C2664: 'int sol::stack::unqualified_pusher<wchar_t,void>::push(lua_State *,wchar_t)': cannot convert argument 2 from 'const std::filesystem::path' to 'wchar_t'
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/stack_core.hpp(897): note: No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/stack_push.hpp(1226): note: see declaration of 'sol::stack::unqualified_pusher<wchar_t,void>::push'
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/stack_core.hpp(897): note: while trying to match the argument list '(lua_State *, const std::filesystem::path)'
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/stack_core.hpp(897): note: the template instantiation context (the oldest one first) is
main.cpp(23): note: see reference to function template instantiation 'sol::table_proxy<sol::global_table &,std::tuple<const char (&)[5]>> &&sol::table_proxy<sol::global_table &,std::tuple<const char (&)[5]>>::operator =<std::filesystem::path>(T &&) &&' being compiled
        with
        [
            T=std::filesystem::path
        ]
main.cpp(23): note: see the first reference to 'sol::table_proxy<sol::global_table &,std::tuple<const char (&)[5]>>::operator =' in 'main'
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/table_proxy.hpp(122): note: see reference to function template instantiation 'sol::table_proxy<sol::global_table &,std::tuple<const char (&)[5]>> &&sol::table_proxy<sol::global_table &,std::tuple<const char (&)[5]>>::set<_Ty>(T &&) &&' being compiled
        with
        [
            _Ty=std::filesystem::path,
            T=std::filesystem::path
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/table_proxy.hpp(88): note: see reference to function template instantiation 'void sol::table_proxy<sol::global_table &,std::tuple<const char (&)[5]>>::tuple_set<0,_Ty>(std::integer_sequence<size_t,0>,T &&) &&' being compiled
        with
        [
            _Ty=std::filesystem::path,
            T=std::filesystem::path
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/table_proxy.hpp(56): note: see reference to function template instantiation 'sol::basic_table_core<true,sol::reference> &sol::basic_table_core<true,sol::reference>::traverse_set<const char(&)[5],_Ty>(const char (&)[5],_Ty &&)' being compiled
        with
        [
            _Ty=std::filesystem::path
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/table_core.hpp(462): note: see reference to function template instantiation 'void sol::basic_table_core<true,sol::reference>::traverse_set_deep<true,false,sol::detail::none,const char(&)[5],_Ty>(int,Key,_Ty &&) const' being compiled
        with
        [
            _Ty=std::filesystem::path,
            Key=const char (&)[5]
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/table_core.hpp(264): note: see reference to function template instantiation 'void sol::stack::set_field<true,false,const char(&)[5],_Ty>(lua_State *,Key,Value &&,int)' being compiled
        with
        [
            _Ty=std::filesystem::path,
            Key=const char (&)[5],
            Value=std::filesystem::path
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/stack_core.hpp(1250): note: see reference to function template instantiation 'void sol::stack::field_setter<char [5],true,false,void>::set<const char(&)[5],_Ty>(lua_State *,Key,Value &&,int)' being compiled
        with
        [
            _Ty=std::filesystem::path,
            Key=const char (&)[5],
            Value=std::filesystem::path
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/stack_field.hpp(217): note: see reference to function template instantiation 'int sol::stack::push<_Ty,>(lua_State *,T &&)' being compiled
        with
        [
            _Ty=std::filesystem::path,
            T=std::filesystem::path
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/stack_core.hpp(878): note: see reference to function template instantiation 'int sol::stack::unqualified_pusher<Tu,void>::push<_Ty>(lua_State *,_Ty &&)' being compiled
        with
        [
            _Ty=std::filesystem::path
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/stack_push.hpp(372): note: see reference to function template instantiation 'int sol::stack::push<sol::detail::as_value_tag<T>,_Ty,,void>(lua_State *,Arg &&)' being compiled
        with
        [
            T=Tu,
            _Ty=std::filesystem::path,
            Arg=std::filesystem::path
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/stack_core.hpp(897): note: see reference to function template instantiation 'int sol::stack::unqualified_pusher<Tu,void>::push<_Ty,>(lua_State *,Arg &&)' being compiled
        with
        [
            _Ty=std::filesystem::path,
            Arg=std::filesystem::path
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/stack_push.hpp(186): note: see reference to function template instantiation 'int sol::stack::unqualified_pusher<Tu,void>::push_keyed<const std::string&,_Ty>(lua_State *,K,_Ty &&)' being compiled
        with
        [
            _Ty=std::filesystem::path,
            K=const std::string &
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/stack_push.hpp(175): note: see reference to function template instantiation 'void sol::stack::stack_detail::set_undefined_methods_on<T>(sol::stack_reference)' being compiled
        with
        [
            T=Tu
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_core.hpp(193): note: see reference to function template instantiation 'void sol::detail::insert_default_registrations<T,sol::detail::indexed_insert&,bool(__cdecl &)(sol::meta_function)>(IFx,Fx)' being compiled
        with
        [
            IFx=sol::detail::indexed_insert &,
            Fx=bool (__cdecl &)(sol::meta_function)
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_core.hpp(126): note: see reference to class template instantiation 'sol::container_detail::u_c_launch<sol::as_container_t<T>>' being compiled
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_container_launch.hpp(132): note: while compiling class template member function 'int sol::container_detail::u_c_launch<sol::as_container_t<T>>::real_pairs_call(lua_State *)'
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_container_launch.hpp(133): note: see reference to alias template instantiation 'sol::container_detail::has_traits_pairs<sol::usertype_container<sol::as_container_t<T>>>' being compiled
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_container_launch.hpp(133): note: see reference to class template instantiation 'sol::container_detail::has_traits_pairs_test<sol::usertype_container<sol::as_container_t<T>>>' being compiled
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_container.hpp(235): note: see reference to class template instantiation 'sol::usertype_container<sol::as_container_t<T>>' being compiled
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_container.hpp(1559): note: see reference to class template instantiation 'sol::container_detail::usertype_container_default<sol::as_container_t<T>,void>' being compiled
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_container.hpp(1366): note: while compiling class template member function 'int sol::container_detail::usertype_container_default<sol::as_container_t<T>,void>::pairs(lua_State *)'
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_container_launch.hpp(125): note: see the first reference to 'sol::container_detail::usertype_container_default<sol::as_container_t<T>,void>::pairs' in 'sol::container_detail::u_c_launch<sol::as_container_t<T>>::real_pairs_traits'
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_container_launch.hpp(133): note: see the first reference to 'sol::container_detail::u_c_launch<sol::as_container_t<T>>::real_pairs_traits' in 'sol::container_detail::u_c_launch<sol::as_container_t<T>>::real_pairs_call'
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_container.hpp(1368): note: see reference to function template instantiation 'int sol::container_detail::usertype_container_default<sol::as_container_t<T>,void>::pairs_associative<false>(std::false_type,lua_State *)' being compiled
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_container.hpp(1232): note: see reference to function template instantiation 'int sol::container_detail::usertype_container_default<sol::as_container_t<T>,void>::next_iter<false>(lua_State *)' being compiled
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_container.hpp(1217): note: see reference to function template instantiation 'int sol::container_detail::usertype_container_default<sol::as_container_t<T>,void>::next_associative<false>(std::false_type,lua_State *)' being compiled
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/usertype_container.hpp(1209): note: see reference to function template instantiation 'int sol::stack::stack_detail::push_reference<wchar_t,const std::filesystem::path&,>(lua_State *,Arg)' being compiled
        with
        [
            Arg=const std::filesystem::path &
        ]
C:\Users\zziger\AppData\Local\.xmake\packages\s\sol2\v3.3.0\1aa9b23f2d2040d49728efabdcb8d03d\include\sol/stack_core.hpp(936): note: see reference to function template instantiation 'int sol::stack::push<Tr,const std::filesystem::path&,,void>(lua_State *,Arg)' being compiled
        with
        [
            Arg=const std::filesystem::path &
        ]

  > in main.cpp

[zziger]

My bad, seems like

namespace sol
{
    template <>
    struct is_automagical<std::filesystem::path> : std::false_type {};
}

fixes the error. Closing the issue.