Feature request for "friendship" of pointers in "C"

[aotto]

Hi, the following scenario has a "definition hole" in the "C" language

code example:

-------------------------
struct base {
 Â  ...
};

struct A {
 Â  struct base obj;
 Â  ...
} aObj;

struct B {
 Â  struct base obj;
 Â  ...
} bObj;

void method_base (struct base * hdl, ...);

method_base(&aObj, ...)
method_base(&bObj, ...)
------------------------

- a POINTER to "A" is also a valid POINTER to "base"

- a POINTER to "B" is also a valid POINTER to "base"

- a POINTER to "base" is NOT a valid POINTER to "A" and "B"

I require a solution for this problem WITHOUT forced pointer cast
code and without "void* and type-check" inflation.

The following solutions are acceptable:

1. "gcc" discover by its own that "base" is a "friend" of "A" and "B".
2. add a "frienddef" keyword like "typedef" using:
 Â Â Â Â  typedef struct base * baseP;
 Â  Â Â  typedef struct AÂ Â Â  * aP;
 Â  Â Â  typedef struct PÂ Â Â  * bP;
 Â Â Â Â  frienddef baseP aP;
 Â Â Â Â  frienddef baseP bP;
3. add a #PRAGMA to enable/disable this feature
4. add a "gcc" api to easy extend "GCC" without being FORCED
 Â Â  to "hack" the core.

thanks for your help