Re: ptrdiff_t overflow checks for malloc-posix etc.

[Paul Eggert]

On 4/18/21 5:13 AM, Bruno Haible wrote:

> > * m4/realloc.m4 (_AC_FUNC_REALLOC_IF):
> > Don’t start with a newline.
>
> This is not very robust. We usually don't care about newlines or useless
> indentation in the generated configure.ac any more.

Yes, I made that change only because I ran into some shell syntax error 
and the change fixed it. I don't recall what the error was and can't 
reproduce it now, so the attached first patch reverts that change.

If we run into further problems in this area, though, perhaps the patch 
should go back in.  Autoconf (which _AC_FUNC_REALLOC_IF is taken from) 
does care about leading newlines, and even if we have a different API in 
Gnulib surely it's better to stick to the Autoconf API in 
Autoconf-replacing macros.

>   if test $REPLACE_REALLOC = 0; then
>     _AC_FUNC_REALLOC_IF([], [REPLACE_REALLOC=1])
>   fi

I confess I don't like the style as much: it makes the shell code a bit 
less readable, at least to me. But it appears that this style isn't 
needed anyway.

I noticed some other incompatibilities with Autoconf _AC_FUNC_REALLOC_IF 
etc. and fixed them too in the attached first patch.

The second patch switches from AS_IF to AS_CASE as that's cleaner in the 
Gnulib version.

0001-malloc-gnu-etc.-sync-better-with-Autoconf.patch
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0002-malloc-gnu-etc.-prefer-AS_CASE-to-woolly-AS_IF.patch
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