--- /dev/null
+# Checking GLR Parsing: Regression Test -*- Autotest -*-
+# Copyright (C) 2002 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2, or (at your option)
+# any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+# 02111-1307, USA.
+
+AT_BANNER([[GLR Regression Test #1.]])
+
+AT_SETUP([Badly Collapsed GLR States])
+
+AT_DATA([glr-regr1.y],
+[[/* Regression Test: Improper state compression */
+/* Reported by Scott McPeak */
+
+%{
+#include <stdio.h> // fgetc, printf
+
+#define YYSTYPE int
+static YYSTYPE exprMerge (YYSTYPE x0, YYSTYPE x1);
+%}
+
+
+%glr-parser
+
+
+/* -------- productions ------ */
+%%
+
+StartSymbol: E { $$=0; } %merge <exprMerge>
+ ;
+
+E: E 'P' E { $$=1; printf("E -> E 'P' E\n"); } %merge <exprMerge>
+ | 'B' { $$=2; printf("E -> 'B'\n"); } %merge <exprMerge>
+ ;
+
+
+
+/* ---------- C code ----------- */
+%%
+
+static YYSTYPE exprMerge (YYSTYPE x0, YYSTYPE x1)
+{
+ printf ("<OR>\n");
+ return 0;
+}
+
+int main()
+{
+ yyparse();
+ return 0;
+}
+
+int yyerror(char const *msg)
+{
+ printf("%s\n", msg);
+ exit(4);
+}
+
+
+int yylex()
+{
+ while (1) {
+ int ch = fgetc(stdin);
+ if (ch == EOF) {
+ return 0; // bison's EOF
+ } else if (ch == 'B' || ch == 'P') {
+ return ch;
+ }
+ }
+}
+]])
+
+AT_CHECK([[bison -o glr-regr1.c glr-regr1.y]], 0, [],
+[glr-regr1.y: warning: 1 shift/reduce conflict
+])
+AT_COMPILE([glr-regr1])
+AT_CHECK([[echo BPBPB | ./glr-regr1]], 0,
+[[E -> 'B'
+E -> 'B'
+E -> E 'P' E
+E -> 'B'
+E -> E 'P' E
+E -> 'B'
+E -> E 'P' E
+E -> E 'P' E
+<OR>
+]], [])
+
+AT_CLEANUP