------- Comment #3 from sebor at roguewave dot com 2008-12-30 20:08 ------- Quoting [lib.istream], p2:
Both [formatted and unformatted] input functions are described as if they obtain (or extract) input characters by calling rdbuf()->sbumpc() or rdbuf()->sgetc(). They may use other public members of istream. sgetc() is required to return the result of underflow(), while sbumpc() is required to return the result of uflow() (there's no requirement to actually call either of these virtual functions, i.e., no Effects clause, but that's a defect in the spec). The submitted test case assumes that read() calls rdbuf()->sgetc() rather than sbumpc() which could be argued makes it invalid. An implementation of istream::read() may call streambuf::xsgetn() but it must avoid calling an xsgetn() overridden in a derived class. Let me open a separate issue for this. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38476
