https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84793
Bug ID: 84793
Summary: missig -Wrestrict accessing a struct and its first
member
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
-Wrestrict correctly complains when memcpy is called to copy from a struct into
itself, but it fails to trigger when the copy is between a struct and its
initial member.
$ cat z.c && gcc -O2 -S -Wall -Wextra -Wpedantic -Wrestrict z.c
extern void* memcpy (void* restrict, const void* restrict, __SIZE_TYPE__);
struct S {
union {
char a[4], b[4];
};
} s;
void f (struct S *p, unsigned n)
{
memcpy (p->a, p->b, n); // -Wrestrict (good)
}
void g (struct S *p, unsigned n)
{
memcpy (p, p->b, n); // missing -Wrestrict
}
z.c: In function ‘f’:
z.c:11:3: warning: ‘memcpy’ source argument is the same as destination
[-Wrestrict]
memcpy (p->a, p->b, n); // -Wrestrict (good)
^~~~~~~~~~~~~~~~~~~~~~
