Build at Windows throws warning at comparism

[matgrundler]

I Am building a project on multiple platforms (Ubuntu 22.04, Windows 11).
With the latest changes of httplib (0.18.1) i will get the following warning when compiling under Windows 11 with mingw64/g++-Compiler (GCC 12):

./include/httplib.h: In function 'std::wstring httplib::detail::u8string_to_wstring(const char*)': ./include/httplib.hpp:2275:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<wchar_t>::size_type' {aka 'long long unsigned int'} [-Wsign-compare] 2275 | if (wlen != ws.size()) { ws.clear(); } | ~~~~~^~~~~~~~~~~~

If i change the line:

auto wlen = ::MultiByteToWideChar(CP_UTF8, 0, s, len, nullptr, 0);

to the following code:

auto wlen = static_cast<long long unsigned int>(::MultiByteToWideChar(CP_UTF8, 0, s, len, nullptr, 0));

this is fixed by explicit cast to the same Type of the later used "ws.size()"-Value

and there are no more warnings from httplib.h.

[yhirose]

@matgrundler thanks for the report!