/* PR c/85931 - -Wsizeof-pointer-memaccess for strncpy with size of source { dg-do compile } { dg-require-effective-target alloca } { dg-options "-O2 -Wall -Wstringop-truncation -ftrack-macro-expansion=0" } */ typedef __SIZE_TYPE__ size_t; extern char* strncpy (char*, const char*, size_t); extern char a3[3], b3[3]; extern char a5[5], b5[5]; extern char ax[], bx[]; struct SA { char a3[3], b3[3]; char a5[5], b5[5]; char ax[]; }; void sink (void*, ...); #define T(d, s, n) sink (strncpy (d, s, n)) void test_array (unsigned n) { T (a3, b3, 3); /* For the following statemenmt, GCC 8.1 issues warning: argument to ‘sizeof’ in ‘strncpy’ call is the same expression as the source; did you mean to use the size of the destination? Since the size of both the source and destination the warning isn't helpful. Verify that it isn't issued. */ T (a3, b3, sizeof b3); /* { dg-bogus "\\\[-Wsizeof-pointer-memaccess" } */ T (a3, ax, sizeof a3); /* { dg-warning "\\\[-Wstringop-truncation" } */ T (ax, a3, sizeof a3); /* { dg-warning "argument to .sizeof. in .strncpy. call is the same expression as the source" } */ char an[n], bn[n]; sink (an, bn); T (an, bn, sizeof bn); /* { dg-bogus "\\\[-Wsizeof-pointer-memaccess" } */ } void test_member_array (struct SA *sa, unsigned n) { T (sa->a3, sa->b3, 3); T (sa->a3, sa->b3, sizeof sa->b3); /* { dg-bogus "\\\[-Wsizeof-pointer-memaccess" } */ T (sa->a3, sa->ax, sizeof sa->a3); /* { dg-warning "\\\[-Wstringop-truncation" } */ T (sa->ax, sa->a3, sizeof sa->a3); /* { dg-warning "argument to .sizeof. in .strncpy. call is the same expression as the source" } */ struct VarLenStruct { char an[n], bn[n]; } x; sink (&x); T (x.an, x.bn, sizeof x.bn); /* { dg-bogus "\\\[-Wsizeof-pointer-memaccess" } */ }