+## ---------------------- ##
+## %precedence suffices. ##
+## ---------------------- ##
+
+AT_SETUP([%precedence suffices])
+
+AT_DATA([input.y],
+[[%precedence "then"
+%precedence "else"
+%%
+stmt:
+ "if" cond "then" stmt
+| "if" cond "then" stmt "else" stmt
+| "stmt"
+;
+
+cond:
+ "exp"
+;
+]])
+
+AT_BISON_CHECK([-o input.c input.y])
+
+AT_CLEANUP
+
+
+## ------------------------------ ##
+## %precedence does not suffice. ##
+## ------------------------------ ##
+
+AT_SETUP([%precedence does not suffice])
+
+AT_DATA([input.y],
+[[%precedence "then"
+%precedence "else"
+%%
+stmt:
+ "if" cond "then" stmt
+| "if" cond "then" stmt "else" stmt
+| "stmt"
+;
+
+cond:
+ "exp"
+| cond "then" cond
+;
+]])
+
+AT_BISON_CHECK([-o input.c input.y], 0, [],
+[[input.y: conflicts: 1 shift/reduce
+input.y:12.3-18: warning: rule useless in parser due to conflicts: cond: cond "then" cond
+]])
+
+AT_CLEANUP
+
+