On Thu, Mar 10, 2022 at 1:40 PM 'wagner riffel' via golang-nuts <
golang-nuts@googlegroups.com> wrote:
> I don't think it's mentioned in the specification, my bet is that
> unless your type requires inifnity amout of memory (eg: `type t struct
> {t}`) or the type is an interface and break its rules, (eg: `type
> iface interface{ iface }`) you can use self-reference.
The validity of `type T *T` in Go is based on two things: 1) The visibility
of the identifier in `type T ...` is specified to start right after the
identifier, 2) It's possible, in this case, to compute the size of type T.
So no problem here.
> You're correct, C doesn't allow self reference in type decl, more ...
In `typedef self *self;` the visibility of the second instance of
identifier `self` starts only after it, ie. preceding the final `;'. So the
first identifier `self`, the one after `typedef` is undefined and that's
the real reason it does not work. However:
----
jnml@e5-1650:~/tmp$ cat main.c
typedef int T;
typedef T T;
int main() {}
jnml@e5-1650:~/tmp$ gcc -Wall main.c
jnml@e5-1650:~/tmp$
----
This works because typedef is equal to Go type aliases. But the full Go
thing cannot work:
----
jnml@e5-1650:~/tmp$ cat main.c
typedef int T;
typedef T *T;
int main() {}
jnml@e5-1650:~/tmp$ gcc -Wall main.c
main.c:2:12: error: conflicting types for âTâ
2 | typedef T *T;
| ^
main.c:1:13: note: previous declaration of âTâ was here
1 | typedef int T;
|
----
Here the problem is that we define T to be two different types, the first
it's an int and the second is a pointer to int.
--
You received this message because you are subscribed to the Google Groups
"golang-nuts" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to golang-nuts+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/golang-nuts/CAA40n-VotEGgVupaJ6S1zRF%3D3hDHDKAz0V5_enaD9EfYfL7t-Q%40mail.gmail.com.
