https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83841
Bug ID: 83841
Summary: missing -Wmemset-elt-size with array element plus
offset
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
The -Wmemset-elt-size warning is issued inconsistently when memset is called
with an array plus offset as the first argument.
$ cat z.c && gcc -S -Wall z.c
int a[3];
void fcst (void)
{
__builtin_memset (a + 1, 0, 2); // missing -Wmemset-elt-size
}
void gcst (void)
{
__builtin_memset (&a + 1, 0, 2); // -Wmemset-elt-size (good)
}
void hcst (void)
{
__builtin_memset (&a[1], 0, 2); // missing -Wmemset-elt-size
}
void fvar (unsigned i)
{
__builtin_memset (a + i, 0, 2); // missing -Wmemset-elt-size
}
void gvar (unsigned i)
{
__builtin_memset (&a + i, 0, 2); // missing -Wmemset-elt-size
}
void hvar (unsigned i)
{
__builtin_memset (&a[i], 0, 2); // missing -Wmemset-elt-size
}
z.c: In function ‘gcst’:
z.c:10:3: warning: ‘__builtin_memset’ writing 2 bytes into a region of size 0
overflows the destination [-Wstringop-overflow=]
__builtin_memset (&a + 1, 0, 2); // -Wmemset-elt-size (good)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
