Re: wishlist: support for shorter pointers

["Rafał Pietrak" <embedded@ztk-rp.eu>]

Hi Jonathan,

W dniu 28.06.2023 o 09:31, Jonathan Wakely pisze:
> 
> 
> On Wed, 28 Jun 2023, 08:14 Rafał Pietrak via Gcc, <gcc@gcc.gnu.org 
[---------]
>     how it looks like. I have a lot of code like this scattered around:
>     -------------------
>                                      y->next = NULL;
>                      if (our) { out->next = a;
>                      for (y = t->HD; y && y->next; y = y->next)
>                      if (y)  y->next = a;
>                              fit->HD = a->next;
>                      fit->win = a->next;
>                              b = a->next;
>     --------------------
>     This is from just one source file, which otherwise is "plain C". If I
>     was to put it into a library that use "asm tweaked fancy pointers", a
>     portable fragment of code becomes "target dedicated" - this is
>     undesired.
> 
> 
> If you use a C++ library type for your pointers the syntax above doesn't 
> need to change, and the fancy pointer type can be implemented portable, 
> with customisation for targets where you could use 16 bits for the pointers.

As you can expect from the problem I've stated - I don't know C++, so 
I'll need some more advice there.

But, before I dive into learning C++ (forgive the naive question).... 
isn't it so, that C++ comes with a heavy runtime? One that will bloat my 
tiny project? Or the bloat comes only when one uses particular 
elaborated class/inheritance scenarios, and this particular case ( for 
(...; ...; x = x->next) {} ) will not draw any of that into this project?

Not knowing C++ and wanting to check your suggestion (before I start 
putting time into learning it), can you pls provide me a sample of code, 
that would replace the following:
----------------
struct test_s {
	struct test_s *next;
	char buff[1];
};
int test_funct(struct test_s *head, char *opt) {
	struct test_s *x = head;
	for (; x; x = x->next) {
		if (!*x->buff) { *x->buff = *opt; break; }
	}
	return x;
}
-----------------

.... and help me compile it into a variant with "normal/natural to 
architecture" pointers, and a variant with "fancy 16-bit" pointers?

Thenx in advance,

-R
PS: as before - I don't get mails from the list, pls CC responses to me.