+ // This actually goes directly against the C++ spec, but the
+ // value_type overload is dangerous, so we're explicitly deleting
+ // any overloads of operator= that could implicitly convert to
+ // value_type.
+ // Note that we do need to explicitly specify the template types because
+ // otherwise MSVC 2017 will aggressively pre-resolve value_type to
+ // traits_type::char_type, which won't compare as equal when determining
+ // which overload the implementation is referring to.
+ // Also note that MSVC 2015 Update 3 requires us to explicitly specify the
+ // namespace in-which to search for basic_fbstring, otherwise it tries to
+ // look for basic_fbstring::basic_fbstring, which is just plain wrong.
+ template <typename TP>
+ typename std::enable_if<
+ std::is_same<
+ typename std::decay<TP>::type,
+ typename folly::basic_fbstring<E, T, A, Storage>::value_type>::value,
+ basic_fbstring<E, T, A, Storage>&>::type
+ operator=(TP c);