Not sure if I understood. the usage of old and new (checked and unchecked) is a challenge.We may have the same headers used in both codes. The other challenging

Not sure if I understood. the usage of old and new (checked and unchecked) is a challenge.We may have the same headers used in both codes. The other challenging is that same source may compile in compiler with or without support. Ownership Feature Strategy (Inspired by stdbool.h) If the compiler supports ownership checks and qualifiers such as _Owner, _View, _Obj_view, etc., it must define __STDC_OWNERSHIP__. However, even if the compiler implements ownership, it is not active by default. The objective is to have a smooth transition allowing some files without checks. For instance, a thirty part code inside your project. For instance, when compiling this file, even if the compiler supports ownership we don't have errors or warnings because the checks are not enabled by default. #include <stdlib.h> int main() { void \* p = malloc(1); } A second define __OWNERSHIP_H__, is used to enable ownership. This define is set when we include <ownership.h> at beginning. #include <ownership.h> #include <stdlib.h> int main() { void \* p = malloc(1); //error: missing owner qualifier } The other advantage of having a <ownership.h> is because owner is a macro that can be defined as empty in case the compiler does not support ownership, allowing the same code to be compiled in compilers without ownership support.