Malloc error when cross compiling libXt-1.2.1

[Thomas Dickey]

On Sun, May 15, 2022 at 07:26:34PM -0400, Thomas Dickey wrote:
> ----- Original Message -----
> | From: "alexandre schenberg" <ale.schenberg at yandex.com>
> | To: xorg at lists.x.org
> | Sent: Sunday, May 15, 2022 7:06:12 PM
> | Subject: Malloc error when cross compiling libXt-1.2.1
> 
> | Hello. When I try to cross compile libXT 1.2.1 (or any version) for i386, I
> | receive:
> | 
> || configure:18569: checking whether malloc(0) returns NULL
> 
> looks like
> 
> https://gitlab.freedesktop.org/xorg/lib/libxt/-/blob/edd70bdfbbd16247e3d9564ca51d864f82626eb7/configure.ac
> 
> XORG_CHECK_MALLOC_ZERO
> 
> which comes from here:
> 
> https://gitlab.freedesktop.org/xorg/util/macros/-/blob/master/xorg-macros.m4.in
> https://gitlab.freedesktop.org/xorg/util/macros/-/blob/master/xorg-macros.m4.in#L1370
> 
> and as explained here
> 
> https://www.gnu.org/software/autoconf/manual/autoconf-2.63/html_node/Runtime.html
> 
> it's lacking a third choice on the end of the AC_RUN_IFELSE macro.
> Overlooked here:
> 
> https://gitlab.freedesktop.org/xorg/util/macros/-/commit/af0164c2ded2dcc95b72ca3b9bfbad9b790490f7

It's used in Alloc.c in Xt:

https://gitlab.freedesktop.org/xorg/lib/libxt/-/blob/edd70bdfbbd16247e3d9564ca51d864f82626eb7/src/Alloc.c#L167

which notwithstanding the comment, the C standard doesn't offer much help:

https://stackoverflow.com/questions/2132273/what-does-malloc0-return

...so the safest thing to do with the macro would be to supply a warning
and define MALLOC_0_RETURNS_NULL
 
-- 
Thomas E. Dickey <dickey at invisible-island.net>
https://invisible-island.net
ftp://ftp.invisible-island.net
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