maint: eliminate special cases of statements after error. * daspk.cc: Eliminate DASPK_ABORT, DASPK_ABORT1, DASPK_ABORT2 macros. * dasrt.cc: Eliminate DASRT_ABORT, DASRT_ABORT1, DASRT_ABORT2 macros. * dassl.cc: Eliminate DASSL_ABORT, DASSL_ABORT1, DASSL_ABORT2 macros. libinterp/corefcn/graphics.cc (Fdrawnow): Reverse order and call gh_manager::unlock() before call to error(). * variables.cc (Fmlock): Adjust indentation. * __glpk__.cc (glpk): Add FIXME note about unreachable code. * __init_fltk__.cc (F__fltk_check__, F__init_fltk__): Place return statement within #ifdef HAVE_FLTK block. * ov-fcn-handle.cc (load_hdf5): eliminate useless statements after error. * ov-java.cc (F__java_exit__): Place return statement within #ifdef HAVE_JAVA block. * octave.cc (octave_process_command_line): Issue warning, which will return, and then call octave_print_terse_usage_and_exit. * lex.ll: Add FIXME notes about unreachable code. * oct-parse.in.yy (source_file): Eliminate useless return after error.

--- a/libinterp/octave.cc
+++ b/libinterp/octave.cc
@@ -709,7 +709,7 @@
   // Check for various incompatible argument pairs
   if (force_gui_option && no_gui_option)
     {
-      error ("only one of --force-gui and --no-gui may be used");
+      warning ("only one of --force-gui and --no-gui may be used");
 
       octave_print_terse_usage_and_exit ();
     }
@@ -717,7 +717,7 @@
   bool script_file = (argc - optind) > 0;
   if (! code_to_eval.empty () && script_file)
     {
-      error ("--eval \"CODE\" and script file are mutually exclusive options");
+      warning ("--eval \"CODE\" and script file are mutually exclusive options");
 
       octave_print_terse_usage_and_exit ();
     }