On 10/01/2017 09:17 AM, Andrew Makhorin wrote: > Hi Heinrich, > > Thank you for your bug report. > >> compiling GLPK 4.63 on arm64 with gcc 7.2 gives the following warning: >> >> misc/wclique1.c: In function ‘_glp_wclique1’: >> misc/wclique1.c:121:7: warning: ‘memset’: specified size between >> 18446744071562067968 and 18446744073709551615 exceeds maximum object >> size 9223372036854775807 [-Wstringop-overflow=] >> memset(&skip[1], 0, sizeof(char) * n); >> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> misc/wclique1.c:123:7: warning: ‘memset’: specified size between >> 18446744071562067968 and 18446744073709551615 exceeds maximum object >> size 9223372036854775807 [-Wstringop-overflow=] >> memset(&d_flag[1], 0, sizeof(char) * n); >> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> > > Please ignore this warning message. The compiler makes a wrong > conclusion that n declared as int can be negative and being converted to > size_t which is unsigned long can result in a huge value (for example, > (size_t)-1 results in 2^64-1). This however cannot happen due to a check > xassert(n >= 0); in line 90.
Compiling should not generate any warnings. Many packages are compiled with -Werror. So this should be fixed in the code. > >> It can be avoided by first converting to unsigned int: >> >> 120 /* initially all vertices are unmarked */ >> 121 memset(&skip[1], 0, sizeof(char) * (unsigned int)n); >> 122 /* clear flags of all vertices */ >> 123 memset(&d_flag[1], 0, sizeof(char) * (unsigned int)n); >> > > Then on a 32-bit platform there will be a similar message, because > converting -1 to unsigned int gives 2^32-1. I have tested on arm 32bit. Yes you are right. Yet still the problem should be fixed and not ignored. Best regards Heinrich _______________________________________________ Bug-glpk mailing list Bug-glpk@gnu.org https://lists.gnu.org/mailman/listinfo/bug-glpk
