[libcxx-commits] [libcxx] [libc++][hardening] Check bounds on arithmetic in __bounded_iter (PR #78876)

[Louis Dionne via libcxx-commits]

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@@ -31,13 +31,10 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 // Iterator wrapper that carries the valid range it is allowed to access.
 //
 // This is a simple iterator wrapper for contiguous iterators that points
-// within a [begin, end) range and carries these bounds with it. The iterator
-// ensures that it is pointing within that [begin, end) range when it is
-// dereferenced.
-//
-// Arithmetic operations are allowed and the bounds of the resulting iterator
-// are not checked. Hence, it is possible to create an iterator pointing outside
-// its range, but it is not possible to dereference it.
+// within a [begin, end] range and carries these bounds with it. The iterator
+// ensures that it is pointing within [begin, end) range when it is
+// dereferenced. It also ensures that it is never iterated outside of
+// [begin, end].
 template <class _Iterator, class = __enable_if_t< __libcpp_is_contiguous_iterator<_Iterator>::value > >
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ldionne wrote:

Unrelated to this patch: can we do it for any random access iterator? Is there any reason why we need a contiguous iterator?

https://github.com/llvm/llvm-project/pull/78876