[libcxx-commits] [libcxx] [libc++] Vectorize std::mismatch with trivially equality comparable types (PR #87716)

[Louis Dionne via libcxx-commits]

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@@ -0,0 +1,120 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ITERATOR_ALIASING_ITERATOR_H
+#define _LIBCPP___ITERATOR_ALIASING_ITERATOR_H
+
+#include <__compare/strong_order.h>
+#include <__config>
+#include <__iterator/concepts.h>
+#include <__iterator/iterator_traits.h>
+#include <__type_traits/is_trivial.h>
+#include <cstddef>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _BaseT, class _Alias>
+struct __aliasing_iterator_wrapper {
+  class __iterator {
+    _BaseT* __base_ = nullptr;
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ldionne wrote:

I would like to add some libc++ specific tests for this class. It's a tricky one, so I think it's worth it. In particular, we should check that it works with non-trivial source types.

The intent would be that these tests fail very obviously in UBSan mode if we're doing something wrong that we missed during this review.

https://github.com/llvm/llvm-project/pull/87716