libstdc++/9024: Input fails after call to basic_filebuf<>::pubsetbuf(0, 0)

[Paolo Carlini]

A memo: while working on a fix for libstdc++/9423 (quite easy by itself),
finally seems obvious how to fix 9024: in _M_underflow_common add a
separate case for !__testget && !__testinit, which simply calls
_M_file.xsgetn(&__c, 1) and returns __ret = traits_type::to_int_type(__c).

Stay tuned!

Paolo.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9024