Warn on missing query feature type declarations

Warn on	missing	query feature type declarations in rank profiles
which use tensors. This may help users to remember to declare them
to avoid running into confuson as tensors are interpreted as
string which are hashed to scalars.

1 files changed, 6 insertions, 1 deletions

diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/Reference.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/Reference.java
index 3c537b53e9d..4622fb2c933 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/Reference.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/Reference.java
@@ -18,7 +18,7 @@ import java.util.Optional;
  *
  * @author bratseth
  */
-public class Reference extends Name {
+public class Reference extends Name implements Comparable<Reference> {
 
     private final int hashCode;
 
@@ -163,4 +163,9 @@ public class Reference extends Name {
         return b;
     }
 
+    @Override
+    public int compareTo(Reference o) {
+        return this.toString().compareTo(o.toString());
+    }
+
 }