* by the compiler. This can only be used within a function.
*
* Example:
- * char *foo_to_char(struct foo *foo)
+ * #include <stddef.h>
+ * ...
+ * static char *foo_to_char(struct foo *foo)
* {
* // This code needs string to be at start of foo.
* BUILD_ASSERT(offsetof(struct foo, string) == 0);