[thradams]

Cake implements defer as an extension, where ownership and defer work together. The flow analysis must be prepared for defer.

    int * owner p = calloc(1, sizeof(int));
    defer free(p);

However, with ownership checks, the code is already safe. This may also change the programmer's style, as generally, C code avoids returns in the middle of the code.

In this scenario, defer makes the code more declarative and saves some lines of code. It can be particularly useful when the compiler supports defer but not ownership.

One difference between defer and ownership checks, in terms of safety, is that the compiler will not prompt you to create the defer. But, with ownership checks, the compiler will require an owner object to hold the result of malloc, for instance. It cannot be ignored.

The same happens with C++ RAII. If you forgot to free something at our destructor or forgot to create the destructor, the compiler will not complain.

In cake ownership this cannot be ignored.

    struct X {
      FILE * owner file;
    };

    int main(){
       struct X x = {};
       //....
       
    } //error x.file not freed