https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90728
Bug ID: 90728
Summary: False positive Wmemset-elt-size with zero size array
Product: gcc
Version: 9.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: yyc1992 at gmail dot com
Target Milestone: ---
The code below comes from a template expansion (when certain cache feature is
disabled) and all the operation on the `buff` member are no-op.
```
#include <string.h>
struct A {
A()
{
memset(&buff, 0xff, sizeof(buff));
}
int buff[0];
};
```
However, this start to raise a warning on GCC 9
```
a.cpp: In constructor 'A::A()':
a.cpp:8:41: warning: 'memset' used with length equal to number of elements
without multiplication by element size [-Wmemset-elt-size]
8 | memset(&buff, 0xff, sizeof(buff));
| ^
```
It seems that the warning logic simply compare the size (as well as checking
element size != 1) without taking into account the 0 size case.
