[SPARK-32931][SQL] Unevaluable Expressions are not Foldable

### What changes were proposed in this pull request?
Unevaluable expressions are not foldable because we don't have an eval for it. This PR is to clean up the code and enforce it.

### Why are the changes needed?
Ensure that we will not hit the weird cases that trigger ConstantFolding.

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
The existing tests.

Closes #29798 from gatorsmile/refactorUneval.

Lead-authored-by: gatorsmile <[email protected]>
Co-authored-by: Xiao Li <[email protected]>
Signed-off-by: Wenchen Fan <[email protected]>

Author: gatorsmile

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

@@ -264,7 +264,6 @@ case class UnresolvedFunction(
   override def children: Seq[Expression] = arguments ++ filter.toSeq
 
   override def dataType: DataType = throw new UnresolvedException(this, "dataType")
-  override def foldable: Boolean = throw new UnresolvedException(this, "foldable")
   override def nullable: Boolean = throw new UnresolvedException(this, "nullable")
   override lazy val resolved = false
 
@@ -452,7 +451,6 @@ case class UnresolvedExtractValue(child: Expression, extraction: Expression)
   override def right: Expression = extraction
 
   override def dataType: DataType = throw new UnresolvedException(this, "dataType")
-  override def foldable: Boolean = throw new UnresolvedException(this, "foldable")
   override def nullable: Boolean = throw new UnresolvedException(this, "nullable")
   override lazy val resolved = false
 
@@ -522,14 +520,12 @@ case class UnresolvedDeserializer(deserializer: Expression, inputAttributes: Seq
 
   override def child: Expression = deserializer
   override def dataType: DataType = throw new UnresolvedException(this, "dataType")
-  override def foldable: Boolean = throw new UnresolvedException(this, "foldable")
   override def nullable: Boolean = throw new UnresolvedException(this, "nullable")
   override lazy val resolved = false
 }
 
 case class GetColumnByOrdinal(ordinal: Int, dataType: DataType) extends LeafExpression
   with Unevaluable with NonSQLExpression {
-  override def foldable: Boolean = throw new UnresolvedException(this, "foldable")
   override def nullable: Boolean = throw new UnresolvedException(this, "nullable")
   override lazy val resolved = false
 }
@@ -547,7 +543,6 @@ case class GetColumnByOrdinal(ordinal: Int, dataType: DataType) extends LeafExpr
 case class UnresolvedOrdinal(ordinal: Int)
     extends LeafExpression with Unevaluable with NonSQLExpression {
   override def dataType: DataType = throw new UnresolvedException(this, "dataType")
-  override def foldable: Boolean = throw new UnresolvedException(this, "foldable")
   override def nullable: Boolean = throw new UnresolvedException(this, "nullable")
   override lazy val resolved = false
 }

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

@@ -298,6 +298,9 @@ abstract class Expression extends TreeNode[Expression] {
  */
 trait Unevaluable extends Expression {
 
+  /** Unevaluable is not foldable because we don't have an eval for it. */
+  final override def foldable: Boolean = false
+
   final override def eval(input: InternalRow = null): Any =
     throw new UnsupportedOperationException(s"Cannot evaluate expression: $this")
 
@@ -318,7 +321,6 @@ trait Unevaluable extends Expression {
  */
 trait RuntimeReplaceable extends UnaryExpression with Unevaluable {
   override def nullable: Boolean = child.nullable
-  override def foldable: Boolean = child.foldable
   override def dataType: DataType = child.dataType
   // As this expression gets replaced at optimization with its `child" expression,
   // two `RuntimeReplaceable` are considered to be semantically equal if their "child" expressions

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

@@ -66,9 +66,6 @@ case class SortOrder(
     sameOrderExpressions: Set[Expression])
   extends UnaryExpression with Unevaluable {
 
-  /** Sort order is not foldable because we don't have an eval for it. */
-  override def foldable: Boolean = false
-
   override def checkInputDataTypes(): TypeCheckResult = {
     if (RowOrdering.isOrderable(dataType)) {
       TypeCheckResult.TypeCheckSuccess

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/interfaces.scala

@@ -20,7 +20,7 @@ package org.apache.spark.sql.catalyst.expressions.aggregate
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.analysis.UnresolvedAttribute
 import org.apache.spark.sql.catalyst.expressions._
-import org.apache.spark.sql.catalyst.expressions.codegen.CodegenFallback
+import org.apache.spark.sql.catalyst.expressions.codegen.{CodegenContext, CodegenFallback, ExprCode}
 import org.apache.spark.sql.types._
 
 /** The mode of an [[AggregateFunction]]. */
@@ -133,7 +133,6 @@ case class AggregateExpression(
   override def children: Seq[Expression] = aggregateFunction +: filter.toSeq
 
   override def dataType: DataType = aggregateFunction.dataType
-  override def foldable: Boolean = false
   override def nullable: Boolean = aggregateFunction.nullable
 
   @transient
@@ -374,8 +373,7 @@ abstract class ImperativeAggregate extends AggregateFunction with CodegenFallbac
  */
 abstract class DeclarativeAggregate
   extends AggregateFunction
-  with Serializable
-  with Unevaluable {
+  with Serializable {
 
   /**
    * Expressions for initializing empty aggregation buffers.
@@ -421,6 +419,12 @@ abstract class DeclarativeAggregate
     /** Represents this attribute at the input buffer side (the data value is read-only). */
     def right: AttributeReference = inputAggBufferAttributes(aggBufferAttributes.indexOf(a))
   }
+
+  final override def eval(input: InternalRow = null): Any =
+    throw new UnsupportedOperationException(s"Cannot evaluate expression: $this")
+
+  final override protected def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode =
+    throw new UnsupportedOperationException(s"Cannot generate code for expression: $this")
 }
 
 

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

@@ -304,7 +304,6 @@ case class MapFromArrays(left: Expression, right: Expression)
  */
 case object NamePlaceholder extends LeafExpression with Unevaluable {
   override lazy val resolved: Boolean = false
-  override def foldable: Boolean = false
   override def nullable: Boolean = false
   override def dataType: DataType = StringType
   override def prettyName: String = "NamePlaceholder"

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

@@ -113,7 +113,6 @@ case class AssertTrue(child: Expression) extends UnaryExpression with ImplicitCa
   since = "1.6.0")
 case class CurrentDatabase() extends LeafExpression with Unevaluable {
   override def dataType: DataType = StringType
-  override def foldable: Boolean = true
   override def nullable: Boolean = false
   override def prettyName: String = "current_database"
 }
@@ -131,7 +130,6 @@ case class CurrentDatabase() extends LeafExpression with Unevaluable {
   since = "3.1.0")
 case class CurrentCatalog() extends LeafExpression with Unevaluable {
   override def dataType: DataType = StringType
-  override def foldable: Boolean = true
   override def nullable: Boolean = false
   override def prettyName: String = "current_catalog"
 }

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

@@ -337,7 +337,6 @@ case class InSubquery(values: Seq[Expression], query: ListQuery)
 
   override def children: Seq[Expression] = values :+ query
   override def nullable: Boolean = children.exists(_.nullable)
-  override def foldable: Boolean = children.forall(_.foldable)
   override def toString: String = s"$value IN ($query)"
   override def sql: String = s"(${value.sql} IN (${query.sql}))"
 }

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

@@ -50,7 +50,6 @@ case class WindowSpecDefinition(
       frameSpecification.isInstanceOf[SpecifiedWindowFrame]
 
   override def nullable: Boolean = true
-  override def foldable: Boolean = false
   override def dataType: DataType = throw new UnsupportedOperationException("dataType")
 
   override def checkInputDataTypes(): TypeCheckResult = {
@@ -144,7 +143,6 @@ case object RangeFrame extends FrameType {
 sealed trait SpecialFrameBoundary extends Expression with Unevaluable {
   override def children: Seq[Expression] = Nil
   override def dataType: DataType = NullType
-  override def foldable: Boolean = false
   override def nullable: Boolean = false
 }
 
@@ -168,7 +166,6 @@ case object CurrentRow extends SpecialFrameBoundary {
 sealed trait WindowFrame extends Expression with Unevaluable {
   override def children: Seq[Expression] = Nil
   override def dataType: DataType = throw new UnsupportedOperationException("dataType")
-  override def foldable: Boolean = false
   override def nullable: Boolean = false
 }
 
@@ -275,7 +272,6 @@ case class UnresolvedWindowExpression(
     windowSpec: WindowSpecReference) extends UnaryExpression with Unevaluable {
 
   override def dataType: DataType = throw new UnresolvedException(this, "dataType")
-  override def foldable: Boolean = throw new UnresolvedException(this, "foldable")
   override def nullable: Boolean = throw new UnresolvedException(this, "nullable")
   override lazy val resolved = false
 }
@@ -287,7 +283,6 @@ case class WindowExpression(
   override def children: Seq[Expression] = windowFunction :: windowSpec :: Nil
 
   override def dataType: DataType = windowFunction.dataType
-  override def foldable: Boolean = windowFunction.foldable
   override def nullable: Boolean = windowFunction.nullable
 
   override def toString: String = s"$windowFunction $windowSpec"
@@ -370,8 +365,11 @@ abstract class OffsetWindowFunction
    * OffsetWindowFunction is executed, the input expression and the default expression. Even when
    * both the input and the default expression are foldable, the result is still not foldable due to
    * the frame.
+   *
+   * Note, the value of foldable is set to false in the trait Unevaluable
+   *
+   * override def foldable: Boolean = false
    */
-  override def foldable: Boolean = false
 
   override def nullable: Boolean = default == null || default.nullable || input.nullable
 

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/v2Commands.scala

@@ -348,7 +348,6 @@ case class MergeIntoTable(
 
 sealed abstract class MergeAction extends Expression with Unevaluable {
   def condition: Option[Expression]
-  override def foldable: Boolean = false
   override def nullable: Boolean = false
   override def dataType: DataType = throw new UnresolvedException(this, "nullable")
   override def children: Seq[Expression] = condition.toSeq
@@ -369,7 +368,6 @@ case class InsertAction(
 }
 
 case class Assignment(key: Expression, value: Expression) extends Expression with Unevaluable {
-  override def foldable: Boolean = false
   override def nullable: Boolean = false
   override def dataType: DataType = throw new UnresolvedException(this, "nullable")
   override def children: Seq[Expression] = key ::  value :: Nil