+## ------------------- ##
+## Reduced Automaton. ##
+## ------------------- ##
+
+# Check that the automaton is that as the for the grammar reduced by
+# hand.
+
+AT_SETUP([Reduced Automaton])
+
+AT_KEYWORDS([report])
+
+# The non reduced grammar.
+# ------------------------
+AT_DATA([[not-reduced.y]],
+[[/* A useless token. */
+%token useless_token
+/* A useful one. */
+%token useful
+%verbose
+%output="not-reduced.c"
+
+%%
+
+exp: useful { /* A useful action. */ }
+ | non_productive { /* A non productive action. */ }
+ ;
+
+not_reachable: useful { /* A not reachable action. */ }
+ ;
+
+non_productive: non_productive useless_token
+ { /* Another non productive action. */ }
+ ;
+%%
+]])
+
+AT_CHECK([[bison not-reduced.y]], 0, [],
+[[not-reduced.y: warning: 2 useless nonterminals and 3 useless rules
+not-reduced.y:14.1-13: warning: useless nonterminal: not_reachable
+not-reduced.y:11.6-19: warning: useless nonterminal: non_productive
+not-reduced.y:11.4-57: warning: useless rule: exp: non_productive
+not-reduced.y:14.14-56: warning: useless rule: not_reachable: useful
+not-reduced.y:17.15-18.63: warning: useless rule: non_productive: non_productive useless_token
+]])
+
+AT_CHECK([[sed -n '/^Grammar/q;/^$/!p' not-reduced.output]], 0,
+[[Useless nonterminals:
+ not_reachable
+ non_productive
+Terminals which are not used:
+ useless_token
+Useless rules
+ 2 exp: non_productive
+ 3 not_reachable: useful
+ 4 non_productive: non_productive useless_token
+]])
+
+# The reduced grammar.
+# --------------------
+AT_DATA([[reduced.y]],
+[[/* A useless token. */
+%token useless_token
+/* A useful one. */
+%token useful
+%verbose
+%output="reduced.c"
+
+%%
+
+exp: useful { /* A useful action. */ }
+// | non_productive { /* A non productive action. */ } */
+ ;
+
+//not_reachable: useful { /* A not reachable action. */ }
+// ;
+
+//non_productive: non_productive useless_token
+// { /* Another non productive action. */ }
+// ;
+%%
+]])
+
+AT_CHECK([[bison reduced.y]])
+
+# Comparing the parsers.
+cp reduced.c expout
+AT_CHECK([sed 's/not-reduced/reduced/g' not-reduced.c], 0, [expout])
+
+AT_CLEANUP
+
+
+