+
+
+
+## --------------- ##
+## Useless Rules. ##
+## --------------- ##
+
+AT_SETUP([Useless Rules])
+
+AT_KEYWORDS([report])
+
+AT_DATA([[input.y]],
+[[%verbose
+%output "input.c"
+%token useful
+%%
+exp: useful;
+useless1: '1';
+useless2: '2';
+useless3: '3';
+useless4: '4';
+useless5: '5';
+useless6: '6';
+useless7: '7';
+useless8: '8';
+useless9: '9';
+]])
+
+AT_CHECK([[bison input.y]], 0, [],
+[[input.y: warning: 9 nonterminals and 9 rules useless in grammar
+input.y:6.1-8: warning: nonterminal useless in grammar: useless1
+input.y:7.1-8: warning: nonterminal useless in grammar: useless2
+input.y:8.1-8: warning: nonterminal useless in grammar: useless3
+input.y:9.1-8: warning: nonterminal useless in grammar: useless4
+input.y:10.1-8: warning: nonterminal useless in grammar: useless5
+input.y:11.1-8: warning: nonterminal useless in grammar: useless6
+input.y:12.1-8: warning: nonterminal useless in grammar: useless7
+input.y:13.1-8: warning: nonterminal useless in grammar: useless8
+input.y:14.1-8: warning: nonterminal useless in grammar: useless9
+input.y:6.11-13: warning: rule useless in grammar: useless1: '1'
+input.y:7.11-13: warning: rule useless in grammar: useless2: '2'
+input.y:8.11-13: warning: rule useless in grammar: useless3: '3'
+input.y:9.11-13: warning: rule useless in grammar: useless4: '4'
+input.y:10.11-13: warning: rule useless in grammar: useless5: '5'
+input.y:11.11-13: warning: rule useless in grammar: useless6: '6'
+input.y:12.11-13: warning: rule useless in grammar: useless7: '7'
+input.y:13.11-13: warning: rule useless in grammar: useless8: '8'
+input.y:14.11-13: warning: rule useless in grammar: useless9: '9'
+]])
+
+AT_CHECK([[sed -n '/^Grammar/q;/^$/!p' input.output]], 0,
+[[Nonterminals useless in grammar
+ useless1
+ useless2
+ useless3
+ useless4
+ useless5
+ useless6
+ useless7
+ useless8
+ useless9
+Terminals unused in grammar
+ '1'
+ '2'
+ '3'
+ '4'
+ '5'
+ '6'
+ '7'
+ '8'
+ '9'
+Rules useless in grammar
+ 2 useless1: '1'
+ 3 useless2: '2'
+ 4 useless3: '3'
+ 5 useless4: '4'
+ 6 useless5: '5'
+ 7 useless6: '6'
+ 8 useless7: '7'
+ 9 useless8: '8'
+ 10 useless9: '9'
+]])
+
+AT_CLEANUP
+
+
+
+## ------------------- ##
+## Reduced Automaton. ##
+## ------------------- ##
+
+# Check that the automaton is that as the for the grammar reduced by
+# hand.
+
+AT_SETUP([Reduced Automaton])
+
+AT_KEYWORDS([report])
+
+# The non reduced grammar.
+# ------------------------
+AT_DATA([[not-reduced.y]],
+[[/* A useless token. */
+%token useless_token
+/* A useful one. */
+%token useful
+%verbose
+%output "not-reduced.c"
+
+%%
+
+exp: useful { /* A useful action. */ }
+ | non_productive { /* A non productive action. */ }
+ ;
+
+not_reachable: useful { /* A not reachable action. */ }
+ ;
+
+non_productive: non_productive useless_token
+ { /* Another non productive action. */ }
+ ;
+%%
+]])
+
+AT_CHECK([[bison not-reduced.y]], 0, [],
+[[not-reduced.y: warning: 2 nonterminals and 3 rules useless in grammar
+not-reduced.y:14.1-13: warning: nonterminal useless in grammar: not_reachable
+not-reduced.y:11.6-19: warning: nonterminal useless in grammar: non_productive
+not-reduced.y:11.6-57: warning: rule useless in grammar: exp: non_productive
+not-reduced.y:14.16-56: warning: rule useless in grammar: not_reachable: useful
+not-reduced.y:17.17-18.63: warning: rule useless in grammar: non_productive: non_productive useless_token
+]])
+
+AT_CHECK([[sed -n '/^Grammar/q;/^$/!p' not-reduced.output]], 0,
+[[Nonterminals useless in grammar
+ not_reachable
+ non_productive
+Terminals unused in grammar
+ useless_token
+Rules useless in grammar
+ 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
+
+
+
+## ------------------- ##
+## Underivable Rules. ##
+## ------------------- ##
+
+AT_SETUP([Underivable Rules])
+
+AT_KEYWORDS([report])
+
+AT_DATA([[input.y]],
+[[%verbose
+%output "input.c"
+%token useful
+%%
+exp: useful | underivable;
+underivable: indirection;
+indirection: underivable;
+]])
+
+AT_CHECK([[bison input.y]], 0, [],
+[[input.y: warning: 2 nonterminals and 3 rules useless in grammar
+input.y:5.15-25: warning: nonterminal useless in grammar: underivable
+input.y:6.14-24: warning: nonterminal useless in grammar: indirection
+input.y:5.15-25: warning: rule useless in grammar: exp: underivable
+input.y:6.14-24: warning: rule useless in grammar: underivable: indirection
+input.y:7.14-24: warning: rule useless in grammar: indirection: underivable
+]])
+
+AT_CHECK([[sed -n '/^Grammar/q;/^$/!p' input.output]], 0,
+[[Nonterminals useless in grammar
+ underivable
+ indirection
+Rules useless in grammar
+ 2 exp: underivable
+ 3 underivable: indirection
+ 4 indirection: underivable
+]])
+
+AT_CLEANUP
+
+
+
+## ---------------- ##
+## Empty Language. ##
+## ---------------- ##
+
+AT_SETUP([Empty Language])
+
+AT_DATA([[input.y]],
+[[%output "input.c"
+%%
+exp: exp;
+]])
+
+AT_CHECK([[bison input.y]], 1, [],
+[[input.y: warning: 2 nonterminals and 2 rules useless in grammar
+input.y:3.1-3: fatal error: start symbol exp does not derive any sentence
+]])
+
+AT_CLEANUP