restrict is a C keyword that particularly used on pointer in order to restrict it to only access the object that it is pointing to. For example, when the restrict keyword is used as below on two pointer parameters in a function:
int function(char* restrict ptr1, char* restrict ptr2);
ptr1 cannot be at the same time pointing to the object that is pointed by ptr2. This is a known pattern in order to constrain the 202205171500#.
The expression could be variable or function (decay to 202202142131#). Therefore, depending on the type of X, it will find the most suitable expression for itself according to the result of controlling expression. The variables in controlling expression including the function parameters should not be qualified types (have identifier 202202111824#, 202202111830#, 202205171452#, 202205171504# and 202202081526#), array types and function types.