* src/reduce.c (reduce_grammar): When the language is empty,

complain about the start symbol, not the axiom.
Use its location.
* tests/reduce.at (Empty Language): New.

ChangeLog

@@ -1,3 +1,10 @@
+2002-07-29  Akim Demaille  <akim@epita.fr>
+
+	* src/reduce.c (reduce_grammar): When the language is empty,
+	complain about the start symbol, not the axiom.
+	Use its location.
+	* tests/reduce.at (Empty Language): New.
+
 2002-07-26  Akim Demaille  <akim@epita.fr>
 
 	* src/reader.h, src/reader.c (gram_error): ... can't get

src/reduce.c

@@ -439,8 +439,9 @@ reduce_grammar (void)
   reduce_print ();
 
   if (!bitset_test (N, axiom->number - ntokens))
-    fatal (_("Start symbol %s does not derive any sentence"),
-	   symbols[axiom->number]->tag);
+    fatal_at (startsymbol_location,
+	      _("start symbol %s does not derive any sentence"),
+	      startsymbol->tag);
 
   /* First reduce the nonterminals, as they renumber themselves in the
      whole grammar.  If you change the order, nonterms would be

tests/reduce.at

@@ -332,3 +332,24 @@ Useless rules
 ]])
 
 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 useless nonterminals and 2 useless rules
+input.y:3.1-3: fatal error: start symbol exp does not derive any sentence
+]])
+
+AT_CLEANUP