sys: util: Add SIZEOF_FIELD() macro

This macro allows to know the size of a struct member at compile time.

Several parts of the Zephyr code are currently using directly the macro
code.

Also added a unit test.

(cherry picked from commit bf8b1d6)

Original-Signed-off-by: Adrien Ricciardi <aricciardi@baylibre.com>
GitOrigin-RevId: bf8b1d6
Change-Id: I0ef08f2e396379a05584e64e570c6187b7a24217
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/5611392
Tested-by: Jeremy Bettis <jbettis@chromium.org>
Tested-by: Fabio Baltieri <fabiobaltieri@google.com>
Reviewed-by: Fabio Baltieri <fabiobaltieri@google.com>
Reviewed-by: Jeremy Bettis <jbettis@chromium.org>
Tested-by: ChromeOS Prod (Robot) <chromeos-ci-prod@chromeos-bot.iam.gserviceaccount.com>
Commit-Queue: Fabio Baltieri <fabiobaltieri@google.com>

include/zephyr/sys/util.h

@@ -271,6 +271,16 @@ extern "C" {
 		((type *)(((char *)(ptr)) - offsetof(type, field))); \
 	})
 
+/**
+ * @brief Report the size of a struct field in bytes.
+ *
+ * @param type The structure containing the field of interest.
+ * @param member The field to return the size of.
+ *
+ * @return The field size.
+ */
+#define SIZEOF_FIELD(type, member) sizeof((((type *)0)->member))
+
 /**
  * @brief Concatenate input arguments
  *

tests/unit/util/main.c

@@ -803,4 +803,19 @@ ZTEST(util, test_CONCAT)
 	zassert_equal(CONCAT(CAT_PART1, CONCAT(CAT_PART2, CAT_PART3)), 123);
 }
 
+ZTEST(util, test_SIZEOF_FIELD)
+{
+	struct test_t {
+		uint32_t a;
+		uint8_t b;
+		uint8_t c[17];
+		int16_t d;
+	};
+
+	BUILD_ASSERT(SIZEOF_FIELD(struct test_t, a) == 4, "The a member is 4-byte wide.");
+	BUILD_ASSERT(SIZEOF_FIELD(struct test_t, b) == 1, "The b member is 1-byte wide.");
+	BUILD_ASSERT(SIZEOF_FIELD(struct test_t, c) == 17, "The c member is 17-byte wide.");
+	BUILD_ASSERT(SIZEOF_FIELD(struct test_t, d) == 2, "The d member is 2-byte wide.");
+}
+
 ZTEST_SUITE(util, NULL, NULL, NULL, NULL, NULL);