shift-expression: additive-expression shift-expression << additive-expression shift-expression >> additive-expression

The operands shall be of integral or unscoped enumeration type and integral
promotions are performed.

The type of the result is that of the promoted
left operand.

The behavior is undefined if the right operand is negative, or greater
than or equal to the width of the promoted left operand.

The value of E1 << E2 is the unique value congruent to
modulo ,
where N is the width of the type of the result.