[libcxx-commits] [libcxx] [lldb] [libcxx] adds size-based `__split_buffer` representation to unstable ABI (PR #139632)

[Nikolas Klauser via libcxx-commits]

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@@ -45,11 +47,232 @@ _LIBCPP_PUSH_MACROS
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+template <class _SplitBuffer>
+class __split_buffer_pointer_layout {
+public: // TODO: make private after vector becomes size-based
+  using reference       = typename _SplitBuffer::reference;
+  using const_reference = typename _SplitBuffer::const_reference;
+  using pointer         = typename _SplitBuffer::pointer;
+  using const_pointer   = typename _SplitBuffer::const_pointer;
+  using size_type       = typename _SplitBuffer::size_type;
+  using allocator_type  = typename _SplitBuffer::allocator_type;
+
+  pointer __first_ = nullptr;
+  pointer __begin_ = nullptr;
+  pointer __end_   = nullptr;
+  _LIBCPP_COMPRESSED_PAIR(pointer, __cap_ = nullptr, allocator_type, __alloc_);
+
+public:
+  static const bool __is_size_based = false;
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philnik777 wrote:

This is a bit smelly. Why do we need to inform `__split_buffer` which memory layout it is using?

https://github.com/llvm/llvm-project/pull/139632