Add an -e option to ocamlyacc to reject grammars with conflicts.

yacc/defs.h

@@ -210,6 +210,7 @@ extern char tflag;
 extern char vflag;
 extern char qflag;
 extern char sflag;
+extern char eflag;
 extern char big_endian;
 
 extern char *myname;
@@ -335,6 +336,7 @@ extern void output (void);
 extern void over_unionized (char *u_cptr) Noreturn;
 extern void prec_redeclared (void);
 extern void polymorphic_entry_point(char *s) Noreturn;
+extern void forbidden_conflicts (void);
 extern void reader (void);
 extern void reflexive_transitive_closure (unsigned int *R, int n);
 extern void reprec_warning (char *s);

yacc/error.c

@@ -313,3 +313,11 @@ void polymorphic_entry_point(char *s)
             myname, s);
     done(1);
 }
+
+void forbidden_conflicts(void)
+{
+    fprintf(stderr,
+            "%s: the grammar has conflicts, but -e was specified\n",
+            myname);
+    done(1);
+}

yacc/main.c

@@ -30,6 +30,7 @@ char rflag;
 char tflag;
 char vflag;
 char qflag;
+char eflag;
 char sflag;
 char big_endian;
 
@@ -160,7 +161,7 @@ void set_signals(void)
 
 void usage(void)
 {
-    fprintf(stderr, "usage: %s [-v] [-q] [-b file_prefix] filename\n",
+    fprintf(stderr, "usage: %s [-v] [-e] [-q] [-b file_prefix] filename\n",
             myname);
     exit(1);
 }
@@ -213,6 +214,10 @@ void getargs(int argc, char **argv)
                 usage();
             continue;
 
+        case 'e':
+            eflag = 1;
+            continue;
+
         default:
             usage();
         }

yacc/mkpar.c

@@ -47,7 +47,11 @@ void make_parser(void)
     find_final_state();
     remove_conflicts();
     unused_rules();
-    if (SRtotal + RRtotal > 0) total_conflicts();
+    if (SRtotal + RRtotal > 0) {
+        total_conflicts();
+        if (eflag)
+            forbidden_conflicts();
+    }
     defreds();
 }