elseif(HAVE_CLZ)

check_cxx_source_compiles("
    int main()
    {
      unsigned a = __builtin_clz(1);
      unsigned long b = __builtin_clzl(1);
      unsigned long long c = __builtin_clzll(1);
    }
    " HAVE_CLZ
  )

add_compile_definitions($<$<BOOL:${HAVE_CLZ}>:HAVE_CLZ>)