[libcxx-commits] [libcxx] [libc++] Replace `__compressed_pair` with `[[no_unique_address]]` (PR #76756)

[Louis Dionne via libcxx-commits]

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@@ -37,49 +37,77 @@ class small_iter_allocator {
   friend bool operator!=(small_iter_allocator, small_iter_allocator) { return false; }
 };
 
+template <class T>
+class final_small_iter_allocator final {
+public:
+  using value_type      = T;
+  using pointer         = small_pointer<T>;
+  using size_type       = std::int16_t;
+  using difference_type = std::int16_t;
+
+  final_small_iter_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  final_small_iter_allocator(final_small_iter_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(final_small_iter_allocator, final_small_iter_allocator) { return true; }
+  friend bool operator!=(final_small_iter_allocator, final_small_iter_allocator) { return false; }
+};
+
 #if __SIZE_WIDTH__ == 64
 
 static_assert(sizeof(std::deque<int>) == 48, "");
 static_assert(sizeof(std::deque<int, min_allocator<int> >) == 48, "");
 static_assert(sizeof(std::deque<int, test_allocator<int> >) == 80, "");
 static_assert(sizeof(std::deque<int, small_iter_allocator<int> >) == 12, "");
+static_assert(sizeof(std::deque<int, final_small_iter_allocator<int> >) == 16, "");
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ldionne wrote:

I think it would be better to land these test changes in a patch first, and then this patch could show that it doesn't change any of the current behavior (except the noted corner-case).

https://github.com/llvm/llvm-project/pull/76756