PVS-Studio warning V575 for Firebird

void FB_CARG Why::UtlInterface::getPerfCounters(
  ...., ISC_INT64* counters)
{
  unsigned n = 0;
  ....
  memset(counters, 0, n * sizeof(ISC_INT64));
  ....
}

This suspicious code was found in Firebird project by PVS-Studio static code analyzer.
Warning message is:
V575 The 'memset' function processes '0' elements. Inspect the third argument. perf.cpp 487

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/