CAST(NULL AS ...) doesn't forget the data type, precision, and scale any longer.

h2/src/main/org/h2/expression/Function.java

@@ -1744,7 +1744,13 @@ public class Function extends Expression implements FunctionCall {
         scale = s;
         displaySize = d;
         if (allConst) {
-            return ValueExpression.get(getValue(session));
+            Value v = getValue(session);
+            if (v == ValueNull.INSTANCE) {
+                if (info.type == CAST || info.type == CONVERT) {
+                    return this;
+                }
+            }
+            return ValueExpression.get(v);
         }
         return this;
     }

h2/src/test/org/h2/test/jdbc/TestMetaData.java

@@ -52,6 +52,7 @@ public class TestMetaData extends TestBase {
         testColumnDefault();
         testCrossReferences();
         testProcedureColumns();
+        testUDTs();
 
         stat = conn.createStatement();
         meta = conn.getMetaData();
@@ -206,7 +207,6 @@ public class TestMetaData extends TestBase {
         // meta.getSuperTables()
         // meta.getSuperTypes()
         // meta.getTypeInfo()
-        // meta.getUDTs()
 
         conn.close();
 
@@ -329,6 +329,17 @@ public class TestMetaData extends TestBase {
         stat.execute("DROP ALIAS PROP");
     }
 
+    private void testUDTs() throws SQLException {
+        meta = conn.getMetaData();
+        ResultSet rs;
+        rs = meta.getUDTs(null, null, null, null);
+        assertResultSetMeta(rs, 7, new String[] { "TYPE_CAT", "TYPE_SCHEM", "TYPE_NAME",
+                "CLASS_NAME", "DATA_TYPE", "REMARKS", "BASE_TYPE"
+                }, new int[] {
+                Types.VARCHAR, Types.VARCHAR, Types.VARCHAR, Types.VARCHAR, Types.SMALLINT, Types.VARCHAR,
+                Types.SMALLINT }, null, null);
+    }
+
     private void testCrossReferences() throws SQLException {
         meta = conn.getMetaData();
         ResultSet rs;