[libcxx-commits] [libcxx] [libc++] Add unsafe-buffer-usage attributes to span, vector, string and string_view (PR #119603)

[via libcxx-commits]

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@@ -57,7 +58,10 @@ class __wrap_iter {
                      int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __wrap_iter(const __wrap_iter<_OtherIter>& __u) _NOEXCEPT
       : __i_(__u.__i_) {}
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 reference operator*() const _NOEXCEPT { return *__i_; }
+  _LIBCPP_VALID_ELEMENT_ACCESS_PRECONDITION _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 reference
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geoffreygaren wrote:

The use case is when you've enabled hardening in libc++ (so you get bounds checking in span::operator[], array::operator[], etc.), but your vendor configuration -- e.g., Darwin user space -- does _not_ enable hardening for iterators (so you can't safely use span.begin(), array.begin(), etc.), because enabling hardening for iterators would break ABI.

https://github.com/llvm/llvm-project/pull/119603