+## --------------- ##
+## Unused values. ##
+## --------------- ##
+
+AT_SETUP([Unused values])
+
+AT_DATA([input.y],
+[[%token <integer> INT
+%type <integer> a b c d e f g h i j k l
+%destructor { destroy ($$); } INT a b c d e f g h i j k l
+%%
+start:
+ 'a' a { $2 } | 'b' b { $2 } | 'c' c { $2 } | 'd' d { $2 } | 'e' e { $2 }
+| 'f' f { $2 } | 'g' g { $2 } | 'h' h { $2 } | 'i' i { $2 } | 'j' j { $2 }
+| 'k' k { $2 } | 'l' l { $2 }
+;
+
+a: INT | INT { } INT { } INT { };
+b: INT | /* empty */;
+c: INT | INT { $1 } INT { } INT { };
+d: INT | INT { } INT { $1 } INT { };
+e: INT | INT { } INT { } INT { $1 };
+f: INT | INT { } INT { } INT { $$ = $1 + $3 + $5; };
+g: INT | INT { $$ } INT { $$ } INT { };
+h: INT | INT { $$ } INT { $$ = $2 } INT { };
+i: INT | INT INT { } { $$ = $1 + $2; };
+j: INT | INT INT { $<integer>$ = 1; } { $$ = $1 + $2; };
+k: INT | INT INT { $$; } { $$ = $3; } { };
+l: INT | INT { $$ = $1; } INT { $$ = $2 + $3; } INT { $$ = $4 + $5; };
+
+]])
+
+AT_CHECK([bison input.y], [], [],
+[[input.y:11.10-32: warning: unset value: $$
+input.y:11.10-32: warning: unused value: $1
+input.y:11.10-32: warning: unused value: $3
+input.y:11.10-32: warning: unused value: $5
+input.y:12.9: warning: empty rule for typed nonterminal, and no action
+input.y:13.10-35: warning: unset value: $$
+input.y:13.10-35: warning: unused value: $3
+input.y:13.10-35: warning: unused value: $5
+input.y:14.10-35: warning: unset value: $$
+input.y:14.10-35: warning: unused value: $3
+input.y:14.10-35: warning: unused value: $5
+input.y:15.10-36: warning: unset value: $$
+input.y:15.10-36: warning: unused value: $3
+input.y:15.10-36: warning: unused value: $5
+input.y:17.10-38: warning: unset value: $$
+input.y:17.10-38: warning: unused value: $1
+input.y:17.10-38: warning: unused value: $2
+input.y:17.10-38: warning: unused value: $3
+input.y:17.10-38: warning: unused value: $4
+input.y:17.10-38: warning: unused value: $5
+input.y:18.10-43: warning: unset value: $$
+input.y:18.10-43: warning: unused value: $1
+input.y:18.10-43: warning: unused value: $3
+input.y:18.10-43: warning: unused value: $4
+input.y:18.10-43: warning: unused value: $5
+input.y:20.10-55: warning: unused value: $3
+input.y:21.10-41: warning: unset value: $$
+input.y:21.10-41: warning: unused value: $1
+input.y:21.10-41: warning: unused value: $2
+input.y:21.10-41: warning: unused value: $4
+]])
+
+AT_CLEANUP
+
+