Cleaned up return type detection

* It now uses the precision for integer types

core/src/main/java/org/apache/calcite/sql/type/ReturnTypes.java

@@ -626,7 +626,7 @@ public static SqlCall stripSeparator(SqlCall call) {
           if (SqlTypeName.INT_TYPES.contains(opType.getSqlTypeName())) {
             if (integerReturnType == null) {
               integerReturnType = opType;
-            } else if (isIntegerTypeLarger(integerReturnType, opType)) {
+            } else if (integerReturnType.getPrecision() < opType.getPrecision()) {
               integerReturnType = opType;
             }
           } else {
@@ -646,26 +646,6 @@ public static SqlCall stripSeparator(SqlCall call) {
             typeFactory.createSqlType(SqlTypeName.INTEGER), true);
       };
 
-  /**
-   * Returns true if type2 is of a larger integer type than type1.
-   *
-   * @param type1 first type
-   * @param type2 second type
-   * @return true if type2 is of a larger integer type than type1
-   */
-  private static boolean isIntegerTypeLarger(RelDataType type1, RelDataType type2) {
-    if (SqlTypeName.TINYINT == type1.getSqlTypeName()) {
-      return SqlTypeName.TINYINT != type2.getSqlTypeName();
-    } else if (SqlTypeName.SMALLINT == type1.getSqlTypeName()) {
-      return SqlTypeName.TINYINT != type2.getSqlTypeName()
-          && SqlTypeName.SMALLINT != type2.getSqlTypeName();
-    } else if (SqlTypeName.INTEGER == type1.getSqlTypeName()) {
-      return SqlTypeName.BIGINT == type2.getSqlTypeName();
-    } else {
-      return false;
-    }
-  }
-
   /**
    * Returns the same type as the multiset carries. The multiset type returned
    * is the least restrictive of the call's multiset operands