C strange shifting behaviour

Question

The following line:

printf("%ld\n", ((long) 7 << 63) >> 63));

Outputs -1

I've checked and

sizeof(long) == 8

Why is this happening?

Answer 1

((long) 7 << 63) >> 63)

调用未定义的行为，因为(long) 7 << 63在long无法表示。