c++ - Why does shifting more than the allowed bits still work? -

i have int8_t , wanted see happen if shift left further 8 bits. did:

int8_t x = 1;  std::cout << (x << 10); 

for reason returns 1024 if type contained enough bits represent number. thought when shift more given bits 0 in bits (or signed overflow/underflow leads undefined behavior). also, ran code give me maximum number of int8_t:

std::numeric_limits<int8_t>::max(); // 127 

the max number of type 127 shifting left can make go higher unsigned type! how possible?

the arguments << being implicitly widened int, , result of x << 10 int.