Hi,

I'm currently hitting some errors trying to build the abseil version in MSVC 2019 with /std:c++17 (pulled in when building tensorflow). Some files (e.g. onepass.cc) appear to assume that absl::string_view::const_iterator is implicitly convertible to const char*, which is true for the absl implementation. However, when abseil detects that the system provides a std::string_view implementation, it defaults to that one, and as far as I can tell there is no conversion guaranteed by the standard (and MSVC does not provide one).

Would it be possible to consider supporting string_view implementations which use opaque absl::string_view::const_iterator types? I'm happy to help.