[klodolph]

The behavior is only well defined if the shift amount is strictly less than the width of the operand. If `size_t` is 32 bits, then shifting right by 32 bits is undefined.

I know of three different ways in which platforms implement shifts by greater than the word size.

[EpicEng]

Yep, you're right. I knew left shift for signed/unsigned as it is more complicated and I've had to look it up more often, but I forgot that right shift can be UB for unsigned integral types as well.