Re: more compilation failures: -DSCM_DEBUG_TYPING_STRICTNESS=2

[Ludovic Courtès]

Hi!

Ken Raeburn <address@hidden> writes:

> On Sep 2, 2009, at 04:08, Ludovic Courtès wrote:
>>> In the Guile case, I'm a tiny bit concerned about some of the
>>> pointer/
>>> int games played (e.g., I'm pretty sure C99 does not guarantee that
>>> you can convert an arbitrary uintptr_t value to pointer and back and
>>> be guaranteed of getting the original value... but I don't know of a
>>> platform that actually violates that assumption), but only a tiny
>>> bit.
>>
>> Really?  I think the whole purpose of `uintptr_t' is to allow that,
>> isn't it?
>
> It's the other way around that's guaranteed to work: void* -> 
> (u)intptr_t -> void*.  So any value originally derived from a valid
> pointer will work, but arbitrary values may not.
[...]

Hmm, I see.  Thanks for the interesting explanation!

Now I understand that I've been lucky enough to live in a beautiful
world with power-of-two pointer types, NULL == 0, etc.  ;-)

Thanks,
Ludo'.