[SPARK-17849][SQL] Fix NPE problem when using grouping sets

## What changes were proposed in this pull request?

Prior this pr, the following code would cause an NPE:
`case class point(a:String, b:String, c:String, d: Int)`

`val data = Seq(
point("1","2","3", 1),
point("4","5","6", 1),
point("7","8","9", 1)
)`
`sc.parallelize(data).toDF().registerTempTable("table")`
`spark.sql("select a, b, c, count(d) from table group by a, b, c GROUPING SETS ((a)) ").show()`

The reason is that when the grouping_id() behavior was changed in #10677, some code (which should be changed) was left out.

Take the above code for example, prior #10677, the bit mask for set "(a)" was `001`, while after #10677 the bit mask was changed to `011`. However, the `nonNullBitmask` was not changed accordingly.

This pr will fix this problem.
## How was this patch tested?

add integration tests

Author: wangyang <[email protected]>

Closes #15416 from yangw1234/groupingid.

(cherry picked from commit fb0d608)
Signed-off-by: Herman van Hovell <[email protected]>

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala

@@ -299,10 +299,15 @@ class Analyzer(
           case other => Alias(other, other.toString)()
         }
 
-        val nonNullBitmask = x.bitmasks.reduce(_ & _)
+        // The rightmost bit in the bitmasks corresponds to the last expression in groupByAliases
+        // with 0 indicating this expression is in the grouping set. The following line of code
+        // calculates the bitmask representing the expressions that absent in at least one grouping
+        // set (indicated by 1).
+        val nullBitmask = x.bitmasks.reduce(_ | _)
 
+        val attrLength = groupByAliases.length
         val expandedAttributes = groupByAliases.zipWithIndex.map { case (a, idx) =>
-          a.toAttribute.withNullability((nonNullBitmask & 1 << idx) == 0)
+          a.toAttribute.withNullability(((nullBitmask >> (attrLength - idx - 1)) & 1) == 1)
         }
 
         val expand = Expand(x.bitmasks, groupByAliases, expandedAttributes, gid, x.child)

sql/core/src/test/resources/sql-tests/inputs/grouping_set.sql

@@ -0,0 +1,17 @@
+CREATE TEMPORARY VIEW grouping AS SELECT * FROM VALUES
+  ("1", "2", "3", 1),
+  ("4", "5", "6", 1),
+  ("7", "8", "9", 1)
+  as grouping(a, b, c, d);
+
+-- SPARK-17849: grouping set throws NPE #1
+SELECT a, b, c, count(d) FROM grouping GROUP BY a, b, c GROUPING SETS (());
+
+-- SPARK-17849: grouping set throws NPE #2
+SELECT a, b, c, count(d) FROM grouping GROUP BY a, b, c GROUPING SETS ((a));
+
+-- SPARK-17849: grouping set throws NPE #3
+SELECT a, b, c, count(d) FROM grouping GROUP BY a, b, c GROUPING SETS ((c));
+
+
+

sql/core/src/test/resources/sql-tests/results/grouping_set.sql.out

@@ -0,0 +1,42 @@
+-- Automatically generated by SQLQueryTestSuite
+-- Number of queries: 4
+
+
+-- !query 0
+CREATE TEMPORARY VIEW grouping AS SELECT * FROM VALUES
+  ("1", "2", "3", 1),
+  ("4", "5", "6", 1),
+  ("7", "8", "9", 1)
+  as grouping(a, b, c, d)
+-- !query 0 schema
+struct<>
+-- !query 0 output
+
+
+
+-- !query 1
+SELECT a, b, c, count(d) FROM grouping GROUP BY a, b, c GROUPING SETS (())
+-- !query 1 schema
+struct<a:string,b:string,c:string,count(d):bigint>
+-- !query 1 output
+NULL	NULL	NULL	3
+
+
+-- !query 2
+SELECT a, b, c, count(d) FROM grouping GROUP BY a, b, c GROUPING SETS ((a))
+-- !query 2 schema
+struct<a:string,b:string,c:string,count(d):bigint>
+-- !query 2 output
+1	NULL	NULL	1
+4	NULL	NULL	1
+7	NULL	NULL	1
+
+
+-- !query 3
+SELECT a, b, c, count(d) FROM grouping GROUP BY a, b, c GROUPING SETS ((c))
+-- !query 3 schema
+struct<a:string,b:string,c:string,count(d):bigint>
+-- !query 3 output
+NULL	NULL	3	1
+NULL	NULL	6	1
+NULL	NULL	9	1