Close gap in ExpandExec

Author: bersprockets

sql/core/src/main/scala/org/apache/spark/sql/execution/ExpandExec.scala

@@ -145,11 +145,12 @@ case class ExpandExec(
     // Part 1: declare variables for each column
     // If a column has the same value for all output rows, then we also generate its computation
     // right after declaration. Otherwise its value is computed in the part 2.
+    lazy val attributeSeq: AttributeSeq = child.output
     val outputColumns = output.indices.map { col =>
       val firstExpr = projections.head(col)
       if (sameOutput(col)) {
         // This column is the same across all output rows. Just generate code for it here.
-        BindReferences.bindReference(firstExpr, child.output).genCode(ctx)
+        BindReferences.bindReference(firstExpr, attributeSeq).genCode(ctx)
       } else {
         val isNull = ctx.freshName("isNull")
         val value = ctx.freshName("value")
@@ -168,7 +169,6 @@ case class ExpandExec(
     // Part 2: switch/case statements
     val cases = projections.zipWithIndex.map { case (exprs, row) =>
       var updateCode = ""
-      val attributeSeq: AttributeSeq = child.output
       for (col <- exprs.indices) {
         if (!sameOutput(col)) {
           val ev = BindReferences.bindReference(exprs(col), attributeSeq).genCode(ctx)