use NamedExpr

Author: mengxr

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala

@@ -146,18 +146,17 @@ case class CreateArray(children: Seq[Expression]) extends Expression {
 /**
  * Returns a Row containing the evaluation of all children expressions.
  */
-case class CreateStruct(children: Seq[Expression]) extends Expression {
+case class CreateStruct(children: Seq[NamedExpression]) extends Expression {
   override type EvaluatedType = Row
 
   override def foldable: Boolean = children.forall(_.foldable)
 
   override lazy val resolved: Boolean = childrenResolved
 
-  override def dataType: StructType = {
+  override lazy val dataType: StructType = {
     assert(resolved, s"CreateStruct is called with unresolved children: $children.")
-    val fields = children.map {
-      case named: NamedExpression =>
-        StructField(named.name, named.dataType, named.nullable, named.metadata)
+    val fields = children.map { child =>
+      StructField(child.name, child.dataType, child.nullable, child.metadata)
     }
     StructType(fields)
   }

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala

@@ -1083,8 +1083,8 @@ class ExpressionEvaluationSuite extends FunSuite {
 
   test("CreateStruct") {
     val row = Row(1, 2, 3)
-    val c1 = 'a.int.at(0)
-    val c3 = 'a.int.at(2)
+    val c1 = 'a.int.at(0).as("a")
+    val c3 = 'c.int.at(2).as("c")
     checkEvaluation(CreateStruct(Seq(c1, c3)), Row(1, 3), row)
   }
 }