PVS-Studio warning V501 for MySQL

static date_time_format_types
get_date_time_result_type(const char *format, uint length)
{
  ...
  for (; val != end && val != end; val++)
  ...
}

This suspicious code was found in MySQL project by PVS-Studio static code analyzer.
Warning message is:
V501 There are identical sub-expressions to the left and to the right of the '&&' operator: val != end && val != end sql item_timefunc.cc

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/