[libcxx-commits] [libcxx] [libc++] Fix ambiguous call to std::max in vector<bool> (PR #119801)

[Louis Dionne via libcxx-commits]

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@@ -0,0 +1,121 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// <vector>
+// vector<bool>
+
+// This test examines ambiguous calls to std::max in vector<bool>
+// Fix https://github.com/llvm/llvm-project/issues/121713
+
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <limits>
+#include <memory>
+#include <new>
+#include <vector>
+
+#include "test_macros.h"
+
+template <typename T, typename SIZE_TYPE = std::size_t, typename DIFF_TYPE = std::ptrdiff_t>
+class sized_allocator {
+  template <typename U, typename Sz, typename Diff>
+  friend class sized_allocator;
+
+public:
+  using value_type                  = T;
+  using size_type                   = SIZE_TYPE;
+  using difference_type             = DIFF_TYPE;
+  using propagate_on_container_swap = std::true_type;
+
+  TEST_CONSTEXPR_CXX20 explicit sized_allocator(int d = 0) : data_(d) {}
+
+  template <typename U, typename Sz, typename Diff>
+  TEST_CONSTEXPR_CXX20 sized_allocator(const sized_allocator<U, Sz, Diff>& a) TEST_NOEXCEPT : data_(a.data_) {}
+
+  TEST_CONSTEXPR_CXX20 T* allocate(size_type n) {
+    if (n > max_size())
+      TEST_THROW(std::bad_array_new_length());
+    return std::allocator<T>().allocate(n);
+  }
+
+  TEST_CONSTEXPR_CXX20 void deallocate(T* p, size_type n) TEST_NOEXCEPT { std::allocator<T>().deallocate(p, n); }
+
+  TEST_CONSTEXPR size_type max_size() const TEST_NOEXCEPT {
+    return std::numeric_limits<size_type>::max() / sizeof(value_type);
+  }
+
+private:
+  int data_;
+
+  TEST_CONSTEXPR friend bool operator==(const sized_allocator& a, const sized_allocator& b) {
+    return a.data_ == b.data_;
+  }
+  TEST_CONSTEXPR friend bool operator!=(const sized_allocator& a, const sized_allocator& b) {
+    return a.data_ != b.data_;
+  }
+};
+
+TEST_CONSTEXPR_CXX20 bool tests() {
+  // The following tests are typical ways to trigger reallocations where `std::max` is used to calculate the capacity.
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ldionne wrote:

For each of these tests, you could test some properties of the vector, like `c.capacity() == X`.

https://github.com/llvm/llvm-project/pull/119801