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

[Nikolas Klauser via lldb-commits]

================
@@ -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;
+
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __split_buffer_pointer_layout() = default;
+
+  _LIBCPP_CONSTEXPR_SINCE_CXX20
+  _LIBCPP_HIDE_FROM_ABI explicit __split_buffer_pointer_layout(const allocator_type& __alloc)
+      : __alloc_(__alloc) {}
+
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI pointer first() _NOEXCEPT { return __first_; }
+
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI const_pointer first() const _NOEXCEPT { return __first_; }
+
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI pointer begin() _NOEXCEPT { return __begin_; }
+
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI const_pointer begin() const _NOEXCEPT { return __begin_; }
+
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI pointer end() _NOEXCEPT { return __end_; }
+
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI pointer end() const _NOEXCEPT { return __end_; }
+
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT {
+    return static_cast<size_type>(__end_ - __begin_);
+  }
+
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI bool empty() const _NOEXCEPT { return __begin_ == __end_; }
+
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI size_type capacity() const _NOEXCEPT {
+    return static_cast<size_type>(__cap_ - __first_);
+  }
+
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __update_first(pointer __new_first) _NOEXCEPT {
----------------
philnik777 wrote:

```suggestion
  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __set_first(pointer __new_first) _NOEXCEPT {
```
Seems like a more canonical name. Same below.

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