[libcxx-commits] [libcxx] [libc++][string] Add regression test for sized new/delete bug (PR #110210)

[Louis Dionne via libcxx-commits]

================
@@ -0,0 +1,64 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// allocate/deallocate must match.
+
+#include <string>
+#include <cassert>
+#include <cstdint>
+#include <type_traits>
+
+#include "test_macros.h"
+
+static int allocated_;
+
+template <class T, class Sz>
+struct test_alloc {
+  typedef Sz size_type;
+  typedef typename std::make_signed<Sz>::type difference_type;
+  typedef T value_type;
+  typedef value_type* pointer;
+  typedef const value_type* const_pointer;
+  typedef typename std::add_lvalue_reference<value_type>::type reference;
+  typedef typename std::add_lvalue_reference<const value_type>::type const_reference;
+
+  template <class U>
+  struct rebind {
+    typedef test_alloc<U, Sz> other;
+  };
+
+  TEST_CONSTEXPR_CXX14 pointer allocate(size_type n, const void* = nullptr) {
+    allocated_ += n;
+    return std::allocator<value_type>().allocate(n);
+  }
+
+  TEST_CONSTEXPR_CXX14 void deallocate(pointer p, size_type s) {
+    allocated_ -= s;
+    std::allocator<value_type>().deallocate(p, s);
+  }
+};
+
+template <class Sz>
+void test() {
+  for (int i = 1; i < 1000; ++i) {
+    using Str = std::basic_string<char, std::char_traits<char>, test_alloc<char, Sz> >;
+    {
+      Str s(i, 't');
+      assert(allocated_ == 0 || allocated_ >= i);
+    }
+  }
+  assert(allocated_ == 0);
+}
+
+int main(int, char**) {
+  test<uint32_t>();
+  test<uint64_t>();
+  test<size_t>();
+}
----------------
ldionne wrote:

```suggestion
  test<size_t>();
  
  return 0;
}
```

This is necessary in Freestanding mode.

https://github.com/llvm/llvm-project/pull/110210