cex: rename -Wcounterexample as -Wcounterexamples, and support -Wcex

Plural vs. singular is always a problem...

But we already have conflicts-sr and conflicts-rr, so counterexamples
makes more sense than counterexample.  Besides, -Wcounterexample will
still be accepted as an unambiguous prefix of -Wcounterexamples.

Add -Wcex as a convenient alias.

While at it, use only "counterexample", never "counter example".

* src/complain.h, src/complain.c
(Wcounterexample, warning_counterexample): Rename as...
(Wcounterexamples, warning_counterexamples): these.
(argmatch_warning_docs): Rename -Wcounterexample as -Wcounterexamples.
(argmatch_warning_args): Likewise.
Add support for -Wcex.
Adjust dependencies.

src/complain.c

@@ -114,7 +114,7 @@ static const argmatch_warning_doc argmatch_warning_docs[] =
 {
   { "conflicts-sr",     N_("S/R conflicts (enabled by default)") },
   { "conflicts-rr",     N_("R/R conflicts (enabled by default)") },
-  { "counterexample",   N_("Conflict counter examples") },
+  { "counterexamples",  N_("generate conflict counterexamples") },
   { "dangling-alias",   N_("string aliases not attached to a symbol") },
   { "deprecated",       N_("obsolete constructs") },
   { "empty-rule",       N_("empty rules without %empty") },
@@ -122,7 +122,7 @@ static const argmatch_warning_doc argmatch_warning_docs[] =
   { "precedence",       N_("useless precedence and associativity") },
   { "yacc",             N_("incompatibilities with POSIX Yacc") },
   { "other",            N_("all other warnings (enabled by default)") },
-  { "all",              N_("all the warnings except 'dangling-alias' and 'yacc'") },
+  { "all",              N_("all the warnings except 'counterexamples', 'dangling-alias' and 'yacc'") },
   { "no-CATEGORY",      N_("turn off warnings in CATEGORY") },
   { "none",             N_("turn off all the warnings") },
   { "error[=CATEGORY]", N_("treat warnings as errors") },
@@ -131,19 +131,19 @@ static const argmatch_warning_doc argmatch_warning_docs[] =
 
 static const argmatch_warning_arg argmatch_warning_args[] =
 {
-  { "all",            Wall },
-  { "conflicts-rr",   Wconflicts_rr },
-  { "conflicts-sr",   Wconflicts_sr },
-  { "counterexample", Wcounterexample },
-  { "dangling-alias", Wdangling_alias },
-  { "deprecated",     Wdeprecated },
-  { "empty-rule",     Wempty_rule },
-  { "everything",     Weverything },
-  { "midrule-values", Wmidrule_values },
-  { "none",           Wnone },
-  { "other",          Wother },
-  { "precedence",     Wprecedence },
-  { "yacc",           Wyacc },
+  { "all",             Wall },
+  { "conflicts-rr",    Wconflicts_rr },
+  { "conflicts-sr",    Wconflicts_sr },
+  { "counterexamples", Wcounterexamples }, { "cex", Wcounterexamples }, // Show cex second.
+  { "dangling-alias",  Wdangling_alias },
+  { "deprecated",      Wdeprecated },
+  { "empty-rule",      Wempty_rule },
+  { "everything",      Weverything },
+  { "midrule-values",  Wmidrule_values },
+  { "none",            Wnone },
+  { "other",           Wother },
+  { "precedence",      Wprecedence },
+  { "yacc",            Wyacc },
   { NULL, Wnone }
 };
 

src/complain.h

@@ -46,7 +46,7 @@ typedef enum
   {
     warning_conflicts_rr,
     warning_conflicts_sr,
-    warning_counterexample,
+    warning_counterexamples,
     warning_dangling_alias,
     warning_deprecated,
     warning_empty_rule,
@@ -107,7 +107,7 @@ typedef enum
 
     Wconflicts_rr     = 1 << warning_conflicts_rr,
     Wconflicts_sr     = 1 << warning_conflicts_sr,
-    Wcounterexample   = 1 << warning_counterexample,
+    Wcounterexamples  = 1 << warning_counterexamples,
     Wdangling_alias   = 1 << warning_dangling_alias,
     Wdeprecated       = 1 << warning_deprecated,
     Wempty_rule       = 1 << warning_empty_rule,
@@ -124,7 +124,7 @@ typedef enum
 
     /**< All above warnings.  */
     Weverything       = ~complaint & ~fatal & ~silent,
-    Wall              = Weverything & ~Wcounterexample & ~Wdangling_alias & ~Wyacc
+    Wall              = Weverything & ~Wcounterexamples & ~Wdangling_alias & ~Wyacc
   } warnings;
 
 /** Whether the warnings of \a flags are all unset.

src/conflicts.c

@@ -723,7 +723,7 @@ rule_conflicts_print (void)
                       r->code, rr, expected_rr);
         }
     }
-  if (warning_is_enabled (Wcounterexample))
+  if (warning_is_enabled (Wcounterexamples))
     report_counterexamples ();
 }
 

src/counterexample.c

@@ -1036,7 +1036,7 @@ generate_next_states (search_state *ss, state_item *conflict1,
 }
 
 /*
- * Perform the actual counter example search,
+ * Perform the actual counterexample search,
  * keeps track of what stage of the search algorithm
  * we are at and gives the appropriate counterexample
  * type based off of time constraints.

src/main.c

@@ -145,7 +145,7 @@ main (int argc, char *argv[])
       conflicts_update_state_numbers (old_to_new, nstates_old);
       free (old_to_new);
     }
-  if (warning_is_enabled (Wcounterexample))
+  if (warning_is_enabled (Wcounterexamples))
     counterexample_init ();
   conflicts_print ();
   timevar_pop (tv_conflicts);