The wrong exception was thrown when trying to reference a table that doesn't…

The wrong exception was thrown when trying to reference a table that doesn't support references such as a tables in the information schema.

h2/src/main/org/h2/command/ddl/AlterTableAddConstraint.java

@@ -190,6 +190,9 @@ public class AlterTableAddConstraint extends SchemaCommand {
         case REFERENTIAL: {
             Table refTable = refSchema.getTableOrView(session, refTableName);
             session.getUser().checkRight(refTable, Right.ALL);
+            if (!refTable.canReference()) {
+                throw DbException.get(ErrorCode.FEATURE_NOT_SUPPORTED_1, "Reference " + refTable.getSQL());
+            }
             boolean isOwner = false;
             IndexColumn.mapColumns(indexColumns, table);
             if (index != null && canUseIndex(index, table, indexColumns)) {

h2/src/main/org/h2/table/FunctionTable.java

@@ -199,4 +199,8 @@ public class FunctionTable extends Table {
         return function.isDeterministic();
     }
 
+    public boolean canReference() {
+        return false;
+    }
+
 }

h2/src/main/org/h2/table/MetaTable.java

@@ -1736,12 +1736,12 @@ public class MetaTable extends Table {
     }
 
     public ArrayList<Index> getIndexes() {
+        ArrayList<Index> list = New.arrayList();
         if (metaIndex == null) {
-            return null;
+            return list;
         }
-        ArrayList<Index>list = New.arrayList();
         list.add(new MetaIndex(this, IndexColumn.wrap(columns), true));
-        // TODO fixed scan index
+        // TODO re-use the index
         list.add(metaIndex);
         return list;
     }
@@ -1772,4 +1772,8 @@ public class MetaTable extends Table {
         return true;
     }
 
+    public boolean canReference() {
+        return false;
+    }
+
 }

h2/src/main/org/h2/table/RangeTable.java

@@ -168,4 +168,8 @@ public class RangeTable extends Table {
         return true;
     }
 
+    public boolean canReference() {
+        return false;
+    }
+
 }

h2/src/main/org/h2/table/Table.java

@@ -255,6 +255,15 @@ public abstract class Table extends SchemaObjectBase {
      */
     public abstract boolean canGetRowCount();
 
+    /**
+     * Check if this table can be referenced.
+     *
+     * @return true if it can
+     */
+    public boolean canReference() {
+        return true;
+    }
+
     /**
      * Check if this table can be dropped.
      *