Add SIZEOF_MEMBER.
Bug: N/A
Test: ran tests
Change-Id: Icb7e8ae83d242c867b71a990b08eb1a62ed1482c
diff --git a/Android.bp b/Android.bp
index 7b0ba11..12b3969 100644
--- a/Android.bp
+++ b/Android.bp
@@ -124,6 +124,7 @@
"errors_test.cpp",
"file_test.cpp",
"logging_test.cpp",
+ "macros_test.cpp",
"parsedouble_test.cpp",
"parseint_test.cpp",
"parsenetaddress_test.cpp",
diff --git a/include/android-base/macros.h b/include/android-base/macros.h
index 25f2ff4..fd6efb2 100644
--- a/include/android-base/macros.h
+++ b/include/android-base/macros.h
@@ -20,6 +20,8 @@
#include <stddef.h> // for size_t
#include <unistd.h> // for TEMP_FAILURE_RETRY
+#include <utility>
+
// bionic and glibc both have TEMP_FAILURE_RETRY, but eg Mac OS' libc doesn't.
#ifndef TEMP_FAILURE_RETRY
#define TEMP_FAILURE_RETRY(exp) \
@@ -114,6 +116,8 @@
((sizeof(a) / sizeof(*(a))) / \
static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))))
+#define SIZEOF_MEMBER(t, f) sizeof(std::declval<t>().f)
+
// Changing this definition will cause you a lot of pain. A majority of
// vendor code defines LIKELY and UNLIKELY this way, and includes
// this header through an indirect path.
diff --git a/macros_test.cpp b/macros_test.cpp
new file mode 100644
index 0000000..2b522db
--- /dev/null
+++ b/macros_test.cpp
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include "android-base/macros.h"
+
+#include <stdint.h>
+
+#include <gtest/gtest.h>
+
+TEST(macros, SIZEOF_MEMBER_macro) {
+ struct S {
+ int32_t i32;
+ double d;
+ };
+ ASSERT_EQ(4U, SIZEOF_MEMBER(S, i32));
+ ASSERT_EQ(8U, SIZEOF_MEMBER(S, d));
+}
