opencomal needed a lot of patching to get it building & running on modern
Slackware. All these patches are by the SlackBuild author.

01-missing_includes.diff
  #include <string.h>

02-vsprintf.diff
  bizarre non-standards-compliant handling of vsprintf() causes immediate
  segfault on startup, when it tries to print the banner.

03-fix_auto_segfault.diff
  missing NULL check, causes segfault in 'auto' mode when a syntax error
  is entered, followed by ^C.

04-mkdir.diff
  fix the mkdir command so it actually reports errors.

05-sys_errlist.diff
  fix deprecation warning.

06-noreturn.diff
  squelch a bunch of spurious 'might be used uninitialized' warnings.
  there are still a couple left, caveat emptor...