Use the `png_jmpbuf' accessor, as recommended since libpng 1.4.0:
http://www.libpng.org/pub/png/src/libpng-1.2.x-to-1.4.x-summary.txt .

--- plotutils-2.6/libplot/z_write.c	2013-07-12 17:19:12.000000000 +0200
+++ plotutils-2.6/libplot/z_write.c	2013-07-12 17:19:07.000000000 +0200
@@ -164,7 +164,7 @@ _pl_z_maybe_output_image (S___(Plotter *
     }
 
   /* cleanup after libpng errors (error handler does a longjmp) */
-  if (setjmp (png_ptr->jmpbuf))
+  if (setjmp (png_jmpbuf (png_ptr)))
     {
       png_destroy_write_struct (&png_ptr, (png_info **)NULL);
       return -1;
@@ -444,7 +444,7 @@ _our_error_fn_stdio (png_struct *png_ptr
 #endif
     }
 
-  longjmp (png_ptr->jmpbuf, 1);
+  longjmp (png_jmpbuf (png_ptr), 1);
 }
 
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<tr><td><span title='2022-11-15 12:16:43 +0100'>2022-11-15</span></td><td><a href='/guix/commit/gnu/installer/hardware.scm?id=514fedbf3966b7fbab31a6c63b4210ec8b5b0c9a'>installer: Report known-unsupported PCI devices.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/hardware.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add it.
* po/guix/POTFILES.in: Add it.
* gnu/installer.scm (installer-steps): Pass #:pci-database to the
'welcome' step procedure.
* gnu/installer/newt.scm (welcome-page): Add #:pci-database and pass it
to 'run-welcome-page'.
* gnu/installer/newt/welcome.scm (check-hardware-support): Add #:pci-database.
Enumerate unsupported PCI devices and run an error page when unsupported
devices are found.
(run-welcome-page): Add #:pci-database and pass it to
'check-hardware-support' and to the recursive call.
* gnu/installer/record.scm (&lt;installer&gt;)[welcome-page]: Adjust comment.
* doc/guix.texi (Hardware Considerations): Mention it.
</span></span></td><td>Ludovic Courtès</td></tr>