b2/lang.y: don't pop fields from the stack before also handling the rule

b2/lang.y

@@ -50,14 +50,18 @@ static void push_field(const struct field *field)
 }
 
 
-static void pop_field(void)
+static void pop_fields(const struct field *last)
 {
 	struct field_stack *entry;
+	const struct field *popped;
 
-	assert(field_stack);
+	do {
-	entry = field_stack;
+		assert(field_stack);
-	field_stack = entry->next;
+		entry = field_stack;
-	free(entry);
+		popped = entry->field;
+		field_stack = entry->next;
+		free(entry);
+	} while (popped != last);
 }
 
 
@@ -241,7 +245,7 @@ rule:
 			$$->any = $5;
 			$$->next = NULL;
 			field_finalize($$);
-			pop_field();
+			pop_fields($$);
 		}
 	;
 
@@ -290,13 +294,14 @@ opt_wildcard:
 
 action:
 		{
+			$<field>$ = (struct field *) top_field();
 			push_field(top_field());
 		}
 	opt_fields opt_rule ';'
 		{
 			$$.fields = $2;
 			$$.rules = $3;
-			pop_field();
+			pop_fields($<field>1);
 		}
 	;
 
@@ -349,14 +354,13 @@ fields:
 		}
 	| field
 		{
+			$1->prev = top_field();
 			push_field($1);
 		}
 	    fields
 		{
 			$$ = $1;
 			$$->next = $3;
-			pop_field();
-			$$->prev = top_field();
 			if ($3)
 				$3->prev = $1;
 		}