https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102848
Bug ID: 102848
Summary: missing warning for bitfield overflow in C
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
G++ warns when assigning to a bit-field a value that cannot be represented in
the object but GCC does not.
$ cat x.c && /build/gcc-master/gcc/xgcc -B /build/gcc-master/gcc -S -Wall
-Wextra x.c
struct A
{
unsigned i, j: 3;
};
void f (struct A *p)
{
p->i = -1; // missing warning
p->j = -1; // missing warning in C, -Woverflow in C++
}
void g (struct A *p)
{
if (p->i < 0) // -Wtype-limits in both C and C++, folded to false
__builtin_abort ();
}
void h (struct A *p)
{
if (p->j < 0) // missing warning in both C and C++, folded to false
__builtin_abort ();
}
x.c: In function ‘g’:
x.c:14:12: warning: comparison of unsigned expression in ‘< 0’ is always false
[-Wtype-limits]
14 | if (p->i < 0)
| ^
