[Bug libstdc++/58815] Casting/Conversion operator for std::decimal not supported

["paolo.carlini at oracle dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58815

--- Comment #15 from Paolo Carlini <paolo.carlini at oracle dot com> ---
A maintainer is also needed in order to *categorize* those potential issues and
plan the work: for example C++11 (+ C++14), which are the primary standards
which we are implementing, don't know about decimal, thus isn't at all clear
that we can conformingly add stuff (thus names) to <type_traits>. More
generally, at this point, that TR is pretty old, isn't clear that we want to
improve the TR code vs freezing it and start work toward providing under some
sort of experimental mode, well separate from standard C++14, something close
to the recent proposal written by Dietmar. See what I mean? If the issue is
just "uncommenting" an operator which essentially was already there and now
thanks to explicit operators in C++11 we know how to do right, that we can do
right now.