[SPARK-16853][SQL] fixes encoder error in DataSet typed select

## What changes were proposed in this pull request?

For DataSet typed select:
```
def select[U1: Encoder](c1: TypedColumn[T, U1]): Dataset[U1]
```
If type T is a case class or a tuple class that is not atomic, the resulting logical plan's schema will mismatch with `Dataset[T]` encoder's schema, which will cause encoder error and throw AnalysisException.

### Before change:
```
scala> case class A(a: Int, b: Int)
scala> Seq((0, A(1,2))).toDS.select($"_2".as[A])
org.apache.spark.sql.AnalysisException: cannot resolve '`a`' given input columns: [_2];
..
```

### After change:
```
scala> case class A(a: Int, b: Int)
scala> Seq((0, A(1,2))).toDS.select($"_2".as[A]).show
+---+---+
|  a|  b|
+---+---+
|  1|  2|
+---+---+
```

## How was this patch tested?

Unit test.

Author: Sean Zhong <seanzhong@databricks.com>

Closes #14474 from clockfly/SPARK-16853.

1 files changed, 11 insertions, 0 deletions

diff --git a/sql/core/src/test/scala/org/apache/spark/sql/DatasetSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/DatasetSuite.scala
index 7e3b7b63d8..8a756fd474 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/DatasetSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/DatasetSuite.scala
@@ -184,6 +184,17 @@ class DatasetSuite extends QueryTest with SharedSQLContext {
       2, 3, 4)
   }
 
+  test("SPARK-16853: select, case class and tuple") {
+    val ds = Seq(("a", 1), ("b", 2), ("c", 3)).toDS()
+    checkDataset(
+      ds.select(expr("struct(_2, _2)").as[(Int, Int)]): Dataset[(Int, Int)],
+      (1, 1), (2, 2), (3, 3))
+
+    checkDataset(
+      ds.select(expr("named_struct('a', _1, 'b', _2)").as[ClassData]): Dataset[ClassData],
+      ClassData("a", 1), ClassData("b", 2), ClassData("c", 3))
+  }
+
   test("select 2") {
     val ds = Seq(("a", 1), ("b", 2), ("c", 3)).toDS()
     checkDataset(