From 3b3dd203be690995d1a89b110322e4eafafc3a3b Mon Sep 17 00:00:00 2001
From: Yakun Xu <xyk@google.com>
Date: Fri, 19 Sep 2025 05:50:15 +0800
Subject: [PATCH] [utils] add a flag to use std new (#11937)

The noexcept placement new is standard in c++11. This commit adds a
config OPENTHREAD_CONFIG_USE_STD_NEW to allow using <new>. The default
behavior is still using OpenThread's own placement new implementation.
---
 src/core/config/misc.h       | 9 +++++++++
 src/include/common/new.hpp   | 6 ++++++
 tests/CMakeLists.txt         | 1 +
 tests/unit/test_platform.cpp | 2 --
 4 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/core/config/misc.h b/src/core/config/misc.h
index fe5aaa62f..ea50a0801 100644
--- a/src/core/config/misc.h
+++ b/src/core/config/misc.h
@@ -617,6 +617,15 @@
 #define OPENTHREAD_EXAMPLES_SIMULATION 0
 #endif
 
+/**
+ * @def OPENTHREAD_CONFIG_USE_STD_NEW
+ *
+ * Define 1 to enable using std <new>.
+ */
+#ifndef OPENTHREAD_CONFIG_USE_STD_NEW
+#define OPENTHREAD_CONFIG_USE_STD_NEW 0
+#endif
+
 /**
  * @}
  */
diff --git a/src/include/common/new.hpp b/src/include/common/new.hpp
index bb49e3c64..1a7fbedff 100644
--- a/src/include/common/new.hpp
+++ b/src/include/common/new.hpp
@@ -34,10 +34,16 @@
 #ifndef OT_INCLUDE_COMMON_NEW_HPP_
 #define OT_INCLUDE_COMMON_NEW_HPP_
 
+#include <openthread/config.h>
+
+#if defined(OPENTHREAD_CONFIG_USE_STD_NEW) && OPENTHREAD_CONFIG_USE_STD_NEW
+#include <new> // IWYU pragma: keep
+#else
 #include <stddef.h>
 
 #include <openthread/platform/toolchain.h>
 
 inline void *operator new(size_t, void *p) throw() { return p; }
+#endif
 
 #endif // OT_INCLUDE_COMMON_NEW_HPP_
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 4fde25208..485d7fb44 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -29,6 +29,7 @@
 option(OT_BUILD_GTEST "enable gtest")
 
 if(OT_FTD AND BUILD_TESTING AND (NOT OT_PLATFORM STREQUAL "nexus"))
+    target_compile_definitions(ot-config INTERFACE "OPENTHREAD_CONFIG_USE_STD_NEW=1")
     add_subdirectory(unit)
     if(OT_BUILD_GTEST)
         add_subdirectory(gtest)
diff --git a/tests/unit/test_platform.cpp b/tests/unit/test_platform.cpp
index 6e313dae6..fa901a98c 100644
--- a/tests/unit/test_platform.cpp
+++ b/tests/unit/test_platform.cpp
@@ -26,8 +26,6 @@
  *  POSSIBILITY OF SUCH DAMAGE.
  */
 
-// Disable OpenThread's own new implementation to avoid duplicate definition
-#define OT_INCLUDE_COMMON_NEW_HPP_
 #include "test_platform.h"
 
 #include <map>