Re: USE_LSB_TAG and MS-DOS

[Stefan Monnier]

> For whom it may concern: I've checked in a change to lisp.h that
> disables the use of USE_LSB_TAG in the MS-DOS port.  USE_LSB_TAG was
> turned on by a recent change in lisp.h because the MS-DOS build uses
> the GNU malloc and GCC, but that caused temacs to crash with SIGABRT
> during loadup when it performed the first GC.

Can you compile with ENABLE_CHECKING and try again?
And give me a backtrace?

> Btw, the way DECL_ALIGN and USE_LSB_TAG are defined on lisp.h doesn't
> leave any elegant way for specific platforms to turn that off without
> cluttering lisp.h with ugly OS-specific #ifdef's.  Perhaps we should
> devise a cleaner way.

It was devised in the hope that it will only be turned on where it's safe.
Obviously, that's not the way it works, but at least it *should* work that
way, so I think we're just hitting a bug.
After all, all we need is to make sure pointers are multiples of 8.
GNU malloc guarantees that AFAIK for malloced objects and DECL_ALIGN allows
to get the same guarantee for static objects, so if we have both the only
reasonf ro USE_LSB_TAG to fail is a bug, right?


        Stefan