CTR55-CPP. Do not use an additive operator on an iterator if the result would overflow

Expressions that have an integral type can be added to or subtracted from a pointer, resulting in a value of the pointer type. If the resulting pointer is not a valid member of the container, or one past the last element of the container, the behavior of the additive operator is undefined . The C++ Standard, [expr.add], paragraph 5 [ ISO/IEC 14882-2014 ], in part, states the following:

If both the pointer operand and the result point to elements of the same array object, or one past the last element of the array object, the evaluation shall not produce an overflow; otherwise, the behavior is undefined.

Because iterators are a generalization of pointers, the same constraints apply to additive operators with random access iterators. Specifically, the C++ Standard, [iterator.requirements.general], paragraph 5, states the following:

Just as a regular pointer to an array guarantees that there is a pointer value pointing past the last element of the array, so for any iterator type there is an iterator value that points past the last element of a corresponding sequence. These values are called past-the-end values. Values of an iterator i for which the expression *i is defined are called dereferenceable . The library never as