bug#70568: 30.0.50; build warnings on 'x86_64-pc-linux-gnu'

[Eli Zaretskii]

> Date: Thu, 25 Apr 2024 17:11:54 +0200
> From:  David Ponce via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Hello,
> 
> When I build Emacs configured for 'x86_64-pc-linux-gnu' on Fedora 39 with gcc 
> 13.2.1
> the below warnings are reported:
> 
> 
> 1) ./configure --with-x-toolkit=lucid --with-native-compilation=no
> 
> ..
>    CC       xterm.o
> xterm.c: In function ‘x_alloc_nearest_color_1’:
> xterm.c:9374:27: warning: potential null pointer dereference 
> [-Wnull-dereference]
>   9374 |   if (dpyinfo->visual_info.class == DirectColor)
>        |       ~~~~~~~~~~~~~~~~~~~~^~~~~~
> xterm.c:9374:27: warning: potential null pointer dereference 
> [-Wnull-dereference]
> ...
>    CC       eval.o
> In file included from eval.c:25:
> lisp.h: In function ‘internal_lisp_condition_case’:
> lisp.h:1129:15: warning: variable ‘sym’ might be clobbered by ‘longjmp’ or 
> ‘vfork’ [-Wclobbered]
>   1129 |   Lisp_Object sym = XSYMBOL_WITH_POS (a)->sym;
>        |               ^~~
> eval.c:1413:43: warning: argument ‘var’ might be clobbered by ‘longjmp’ or 
> ‘vfork’ [-Wclobbered]
>   1413 | internal_lisp_condition_case (Lisp_Object var, Lisp_Object bodyform,
>        |                               ~~~~~~~~~~~~^~~
> ...
> 
> 2) ./configure --with-x-toolkit=gtk3 --with-cairo-xcb 
> --with-native-compilation=no
> 
> ...
>    CC       eval.o
> In file included from eval.c:25:
> lisp.h: In function ‘internal_lisp_condition_case’:
> lisp.h:1129:15: warning: variable ‘sym’ might be clobbered by ‘longjmp’ or 
> ‘vfork’ [-Wclobbered]
>   1129 |   Lisp_Object sym = XSYMBOL_WITH_POS (a)->sym;
>        |               ^~~
> eval.c:1413:43: warning: argument ‘var’ might be clobbered by ‘longjmp’ or 
> ‘vfork’ [-Wclobbered]
>   1413 | internal_lisp_condition_case (Lisp_Object var, Lisp_Object bodyform,
>        |                               ~~~~~~~~~~~~^~~
> ...
> 
> 
> In both cases (Lucid, gtk3) the reported warnings don't seem to affect run.
> Thanks

Paul, are those real warnings, or just false alarms?