Function test_sprintf

test/printf-test.cc:33–35

// format strings in MSVC.
template <typename... Args>
auto test_sprintf(fmt::string_view format, const Args&... args) -> std::string {
  return fmt::sprintf(format, args...);
}
template <typename... Args>
auto test_sprintf(fmt::basic_string_view<wchar_t> format, const Args&... args)
    -> std::wstring {