🚀 go-pugleaf

torek@elf.bsdi.com (Chris Torek) wrote:

[ ... ] 
> I looked
>for any sort of limit on recursion depth and found nothing.  Section
>2.2.4 (5.2.4 in ISO?) says essentially nothing about the runtime
>environment.  We know that at least one program containing one
>32767-byte object must be accepted at compile time (in a hosted
>environment), but do we have any guarantees or limits on recursion
>depth?  If I write an otherwise strictly conformant program that
>recurses anywhere from one to ten million times, under which
>failure(s), if any, can I claim to have found a non-conformant
>system?  Section 3.3.2.2 guarantees me recursive calls, so what,
>if anything, makes (say) the 428th special when it fails?

As far as I can tell, there's no guarantee about anything that would
typically involve stack-size.  Along with no guarantee of depth of
recursion, you have no guarantee about _where_ you can allocate your
32767 byte object - it may have to be automatic, or it may have to be
static to suceed.

My inclincation would be to replace the requirement for a single 32767
byte variable with:

- one 32767 byte variable of auto storage class
- one 32767 byte variable of static storage class

and add:

- ability to call functions having any combination of arguments and
parameters totalling 3 variables of any type, to a total depth of 511,
not including the initial invocation of `main'.
(all three requirements applying only to hosted implementations.)

Under the present rules, you could make a pretty good case that no
program that uses a variable is strictly conforming, since there's no
guarantee as to whether any amount of storage is supported in the
storage class used by that variable.

These rules would be a considerable step toward allowing considerably
more to be strictly conforming, but are still easily met on nearly any
current implementation.
    Later,
    Jerry.

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