a7da488130
* include/std/istream (__is_convertible_to_basic_istream): New. (__is_extractable): Likewise. (operator>>(basic_istream<_CharT, _Traits>&&, _Tp&&)): Turn the stream parameter into a template parameter and constrain. * include/std/ostream (__is_convertible_to_basic_ostream): New. (__is_insertable): Likewise. (operator<<(basic_ostream<_CharT, _Traits>&&, const _Tp&)): Turn the stream parameter into a template parameter and constrain. * testsuite/27_io/basic_istream/extractors_other/char/4.cc: New. * testsuite/27_io/basic_istream/extractors_other/wchar_t/4.cc: Likewise. * testsuite/27_io/basic_ostream/inserters_other/char/6.cc: Likewise. * testsuite/27_io/basic_ostream/inserters_other/wchar_t/6.cc: Likewise. From-SVN: r243006