[PATCH] malloc: fix undefined behavior in obstack.h [BZ #32393]

[Collin Funk]

Paul Eggert <eggert@cs.ucla.edu> writes:

> Let's call this new macro __PTR_UINT_TYPE instead, to avoid namespace
> pollution.

I didn't like adding PTR_UINT_TYPE, but it seemed better than including
an entire header.

Using __PTR_UINT_TYPE is reasonable. Just slightly wonky with
PTR_INT_TYPE.

> This collides with Gnulib, which needs to do this a different way to
> avoid a compiler error with Oracle Developer Studio. Although
> admittedly it'll take a bit of work to merge with Gnulib, let's not
> make merging harder.

Right. I was 99% sure that glibc did not care about the
__SMALL_PTRDIFF_T case per the comment in obstack.m4:

    dnl SMALL_PTRDIFF_T is expected to be 1 only on old / exotic platforms
    dnl such as Windows 3.1 and AS/400

But wanted to be certain. Thanks for checking.

> How about the attached patch instead?

Looks good to me, thanks.

Collin