[SPARK-11311][SQL] spark cannot describe temporary functions

When describe temporary function, spark would return 'Unable to find function', this is not right.

Author: Daoyuan Wang <daoyuan.wang@intel.com>

Closes #9277 from adrian-wang/functionreg.

sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUDFs.scala

@@ -119,7 +119,11 @@ private[hive] class HiveFunctionRegistry(underlying: analysis.FunctionRegistry)
           annotation.value(),
           annotation.extended()))
       } else {
-        None
+        Some(new ExpressionInfo(
+          info.getFunctionClass.getCanonicalName,
+          name,
+          null,
+          null))
       }
     }.getOrElse(None))
   }

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveQuerySuite.scala

@@ -953,6 +953,16 @@ class HiveQuerySuite extends HiveComparisonTest with BeforeAndAfter {
     sql("DROP TABLE t1")
   }
 
+  test("CREATE TEMPORARY FUNCTION") {
+    val funcJar = TestHive.getHiveFile("TestUDTF.jar").getCanonicalPath
+    sql(s"ADD JAR $funcJar")
+    sql(
+      """CREATE TEMPORARY FUNCTION udtf_count2 AS
+        | 'org.apache.spark.sql.hive.execution.GenericUDTFCount2'""".stripMargin)
+    assert(sql("DESCRIBE FUNCTION udtf_count2").count > 1)
+    sql("DROP TEMPORARY FUNCTION udtf_count2")
+  }
+
   test("ADD FILE command") {
     val testFile = TestHive.getHiveFile("data/files/v1.txt").getCanonicalFile
     sql(s"ADD FILE $testFile")