[libc-commits] [libc] [libc] Implement CheckedPtr utility (PR #234646)

[Pavel Labath via libc-commits]

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@@ -0,0 +1,297 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Unittests for CheckedPtr and make_unique.
+///
+//===----------------------------------------------------------------------===//
+
+#include "src/__support/CPP/type_traits.h"
+#include "src/__support/CPP/unique_ptr.h"
+#include "src/__support/CPP/utility.h"
+#include "src/__support/alloc-checker.h"
+#include "src/__support/checked_ptr.h"
+#include "test/UnitTest/Test.h"
+
+using LIBC_NAMESPACE::AllocChecker;
+using LIBC_NAMESPACE::CheckedPtr;
+using LIBC_NAMESPACE::make_unique;
+using LIBC_NAMESPACE::cpp::is_constructible_v;
+using LIBC_NAMESPACE::cpp::move;
+using LIBC_NAMESPACE::cpp::unique_ptr;
+
+// Verify compile-time properties:
+// - Non-copyable and non-default-constructible.
+// - Explicit conversion to bool is only allowed on non-const lvalues/rvalues.
+static_assert(!is_constructible_v<CheckedPtr<int>>);
+static_assert(!is_constructible_v<CheckedPtr<int>, const CheckedPtr<int> &>);
+static_assert(is_constructible_v<bool, CheckedPtr<int> &>);
+static_assert(!is_constructible_v<bool, const CheckedPtr<int> &>);
+static_assert(is_constructible_v<bool, CheckedPtr<int[]> &>);
+static_assert(!is_constructible_v<bool, const CheckedPtr<int[]> &>);
+
+struct DestructTracker {
+  int *destruct_count = nullptr;
+  DestructTracker() = default;
+  DestructTracker(int *count) : destruct_count(count) {}
+  ~DestructTracker() {
+    if (destruct_count)
+      (*destruct_count)++;
+  }
+};
+
+struct Foo {
+  int val;
+  Foo(int v) : val(v) {}
+};
+
+struct Base {
+  int val;
+  virtual ~Base() = default;
+  Base(int v) : val(v) {}
+};
+
+struct Derived : public Base {
+  Derived(int v) : Base(v) {}
+};
+
+struct CustomDeleter {
+  int *count;
+  void operator()(int *p) const {
+    (*count)++;
+    delete p;
+  }
+};
+
+struct CustomArrayDeleter {
+  int *count;
+  void operator()(int *p) const {
+    if (count)
+      (*count)++;
+    delete[] p;
+  }
+};
+
+TEST(LlvmLibcCheckedPtrTest, BasicMakeUniqueAndAccess) {
+  int destruct_count = 0;
+  {
+    auto ptr = make_unique<DestructTracker>(&destruct_count);
+    ASSERT_TRUE(static_cast<bool>(ptr));
+
+    // Once checked, access via const reference is valid and safe.
+    const auto &cref = ptr;
+    ASSERT_EQ(*cref->destruct_count, 0);
+    ASSERT_EQ(*(*cref).destruct_count, 0);
+  }
+  ASSERT_EQ(destruct_count, 1);
+}
+
+TEST(LlvmLibcCheckedPtrTest, NullptrCheck) {
+  CheckedPtr<int> ptr(nullptr);
+  ASSERT_FALSE(static_cast<bool>(ptr));
+}
+
+TEST(LlvmLibcCheckedPtrTest, MoveRequiresRecheck) {
+  int destruct_count = 0;
+  {
+    auto ptr1 = make_unique<DestructTracker>(&destruct_count);
+    ASSERT_TRUE(static_cast<bool>(ptr1));
+
+    // Even though ptr1 was checked, moving into ptr2 requires checking ptr2.
+    CheckedPtr<DestructTracker> ptr2(move(ptr1));
+    ASSERT_TRUE(static_cast<bool>(ptr2));
+    ASSERT_EQ(*ptr2->destruct_count, 0);
+  }
+  ASSERT_EQ(destruct_count, 1);
+}
+
+TEST(LlvmLibcCheckedPtrTest, MoveUncheckedThenCheck) {
+  int destruct_count = 0;
+  {
+    auto ptr1 = make_unique<DestructTracker>(&destruct_count);
+    // Move before checking: ptr1 is disarmed; ptr2 must be checked.
+    CheckedPtr<DestructTracker> ptr2(move(ptr1));
+    ASSERT_TRUE(static_cast<bool>(ptr2));
+    ASSERT_EQ(*ptr2->destruct_count, 0);
+  }
+  ASSERT_EQ(destruct_count, 1);
+}
+
+TEST(LlvmLibcCheckedPtrTest, MoveAssignment) {
+  int destruct_count1 = 0;
+  int destruct_count2 = 0;
+  {
+    auto ptr1 = make_unique<DestructTracker>(&destruct_count1);
+    auto ptr2 = make_unique<DestructTracker>(&destruct_count2);
----------------
labath wrote:

Done.

https://github.com/llvm/llvm-project/pull/234646