Undefined Reference Errors When Using PFD_SKIP_IMPLEMENTATION

[Chuvi-w]

I've got linking errors like this
in function main':
ld-temp.o:(.text.main+0x12): undefined reference to pfd::settings::available()' ld-temp.o:(.text.main+0x24): undefined reference to pfd::settings::verbose(bool)'
ld-temp.o:(.text.main+0xb5): undefined reference to pfd::notify::notify(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, pfd::icon)' ld-temp.o:(.text.main+0x1fd): undefined reference to pfd::message::message(std::__cxx11::basic_string<char, std::char_traits, std::allocator > const&, std::__cxx11::basic_string<char, std::char_traits, std::allocator > const&, pfd::choice, pfd::icon)'
ld-temp.o:(.text.main+0x22a): undefined reference to pfd::internal::dialog::ready(int) const'
And so on.
I've created sample on godbolt.

https://godbolt.org/z/r9Ga8E6xj

I think, that external-defined functions shouldn't be marked as inline