Robert Leahy d4a0917821 RandomAccessIterator + 0 ...

Previously the iterators of boost::container::deque would assert when
zero was added to them in at least the following situations:

- The iterator was obtained by a call to boost::container::deque::begin
  and boost::container::deque::empty returns true
- The iterator was default constructed

This is inconsistent with the way in which the iterators of boost::
container::deque have behaved historically and is also inconsistent
with an understanding of iterators developed by analogy with pointers:

- Adding zero to a null pointer is valid despite the fact the null
  pointer cannot be dereferenced
- Adding zero to a pointer that is one past the end yields a pointer
  which is still one past the end and thus which has well defined
  semantics

Fixed this issue and codified the expected behavior in unit tests.

2019-12-22 20:03:57 -05:00

4.9 KiB

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