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-rw-r--r--absl/base/BUILD.bazel1
-rw-r--r--absl/base/CMakeLists.txt1
-rw-r--r--absl/base/internal/hide_ptr.h49
3 files changed, 51 insertions, 0 deletions
diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel
index 5c05c67831a2..3d3c7aea57b6 100644
--- a/absl/base/BUILD.bazel
+++ b/absl/base/BUILD.bazel
@@ -102,6 +102,7 @@ cc_library(
 cc_library(
     name = "base_internal",
     hdrs = [
+        "internal/hide_ptr.h",
         "internal/identity.h",
         "internal/inline_variable.h",
         "internal/invoke.h",
diff --git a/absl/base/CMakeLists.txt b/absl/base/CMakeLists.txt
index 45640562786f..303533e26d1b 100644
--- a/absl/base/CMakeLists.txt
+++ b/absl/base/CMakeLists.txt
@@ -36,6 +36,7 @@ list(APPEND BASE_INTERNAL_HEADERS
   "internal/endian.h"
   "internal/exception_testing.h"
   "internal/exception_safety_testing.h"
+  "internal/hide_ptr.h"
   "internal/identity.h"
   "internal/invoke.h"
   "internal/inline_variable.h"
diff --git a/absl/base/internal/hide_ptr.h b/absl/base/internal/hide_ptr.h
new file mode 100644
index 000000000000..2c2e11f679a0
--- /dev/null
+++ b/absl/base/internal/hide_ptr.h
@@ -0,0 +1,49 @@
+// Copyright 2018 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_BASE_INTERNAL_HIDE_PTR_H_
+#define ABSL_BASE_INTERNAL_HIDE_PTR_H_
+
+#include <cstdint>
+
+namespace absl {
+namespace base_internal {
+
+// Arbitrary value with high bits set. Xor'ing with it is unlikely
+// to map one valid pointer to another valid pointer.
+constexpr uintptr_t HideMask() {
+  static_assert(sizeof(uintptr_t) == 4 || sizeof(uintptr_t) == 8,
+                "uintptr_t must be 32 or 64 bits");
+  return sizeof(uintptr_t) == 8 ? 0xF03A5F7BF03A5F7BULL : 0xF03A5F7BUL;
+}
+
+// Hide a pointer from the leak checker. For internal use only.
+// Differs from absl::IgnoreLeak(ptr) in that absl::IgnoreLeak(ptr) causes ptr
+// and all objects reachable from ptr to be ignored by the leak checker.
+template <class T>
+inline uintptr_t HidePtr(T* ptr) {
+  return reinterpret_cast<uintptr_t>(ptr) ^ HideMask();
+}
+
+// Return a pointer that has been hidden from the leak checker.
+// For internal use only.
+template <class T>
+inline T* UnhidePtr(uintptr_t hidden) {
+  return reinterpret_cast<T*>(hidden ^ HideMask());
+}
+
+}  // namespace base_internal
+}  // namespace absl
+
+#endif  // ABSL_BASE_INTERNAL_HIDE_PTR_H_