[SPARK-12578][SQL] Distinct should not be silently ignored when used in an aggregate function with OVER clause

JIRA: https://issues.apache.org/jira/browse/SPARK-12578

Slightly update to Hive parser. We should keep the distinct keyword when used in an aggregate function with OVER clause. So the CheckAnalysis will detect it and throw exception later.

Author: Liang-Chi Hsieh <viirya@gmail.com>

Closes #10557 from viirya/keep-distinct-hivesql.

sql/hive/src/main/antlr3/org/apache/spark/sql/parser/IdentifiersParser.g

@@ -195,7 +195,7 @@ function
     RPAREN (KW_OVER ws=window_specification)?
            -> {$star != null}? ^(TOK_FUNCTIONSTAR functionName $ws?)
            -> {$dist == null}? ^(TOK_FUNCTION functionName (selectExpression+)? $ws?)
-                            -> ^(TOK_FUNCTIONDI functionName (selectExpression+)?)
+                            -> ^(TOK_FUNCTIONDI functionName (selectExpression+)? $ws?)
     ;
 
 functionName

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

@@ -915,6 +915,27 @@ class SQLQuerySuite extends QueryTest with SQLTestUtils with TestHiveSingleton {
       ).map(i => Row(i._1, i._2, i._3, i._4)))
   }
 
+  test("window function: distinct should not be silently ignored") {
+    val data = Seq(
+      WindowData(1, "a", 5),
+      WindowData(2, "a", 6),
+      WindowData(3, "b", 7),
+      WindowData(4, "b", 8),
+      WindowData(5, "c", 9),
+      WindowData(6, "c", 10)
+    )
+    sparkContext.parallelize(data).toDF().registerTempTable("windowData")
+
+    val e = intercept[AnalysisException] {
+      sql(
+        """
+          |select month, area, product, sum(distinct product + 1) over (partition by 1 order by 2)
+          |from windowData
+        """.stripMargin)
+    }
+    assert(e.getMessage.contains("Distinct window functions are not supported"))
+  }
+
   test("window function: expressions in arguments of a window functions") {
     val data = Seq(
       WindowData(1, "a", 5),