https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107754
Bug ID: 107754
Summary: Confusing -Warray-bounds warning with strcpy
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: nightstrike at gmail dot com
Target Milestone: ---
Metabug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=warray-bounds
// Compile with GCC 12.2.0 with -O2:
// warning: ‘strcpy’ offset 0 is out of the bounds [0, 0] [-Warray-bounds]
// no warning without -O2
struct Inst;
struct Class { int offset; };
static struct Class * classFoo; // No problem without static here
struct Foo
{
unsigned int a; // no problem if commented out
char bar[1024];
};
void setFoo(struct Inst * this, const char * value)
{
struct Foo * ptr = (struct Foo *)(this ? (((char *)this) + classFoo->offset)
: 0);
__builtin_strcpy(ptr->bar, value);
}
$ gcc-12 -c -O2 -Warray-bounds a.c -o /dev/null
a.c: In function 'setFoo':
a.c:19:4: warning: '__builtin_strcpy' offset 0 is out of the bounds [0, 0]
[-Warray-bounds]
19 | __builtin_strcpy(ptr->bar, value);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
