* include/std/std_fstream.h (basic_filebuf::sync): Hoist unconditional flush on lower-layer handle to here... * include/bits/fstream.tcc (basic_filebuf::_M_really_overflow): ...from here. Optimize remaining _M_file.sync() call pattern. * testsuite/27_io/narrow_stream_objects.cc (test04): New test. (test05): Likewise. From-SVN: r52699