[SPARK-9142][SQL] remove more self type in catalyst

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

@@ -43,7 +43,7 @@ import org.apache.spark.sql.types._
  *
  * See [[Substring]] for an example.
  */
-abstract class Expression extends TreeNode[Expression] with Product {
+abstract class Expression extends TreeNode[Expression] {
 
   /**
    * Returns true when an expression is a candidate for static evaluation before the query is

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

@@ -77,7 +77,7 @@ abstract class UnaryMathExpression(f: Double => Double, name: String)
 }
 
 abstract class UnaryLogExpression(f: Double => Double, name: String)
-    extends UnaryMathExpression(f, name) { self: Product =>
+    extends UnaryMathExpression(f, name) {
 
   // values less than or equal to yAsymptote eval to null in Hive, instead of NaN or -Infinity
   protected val yAsymptote: Double = 0.0

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/QueryPlan.scala

@@ -22,7 +22,7 @@ import org.apache.spark.sql.catalyst.trees.TreeNode
 import org.apache.spark.sql.types.{ArrayType, DataType, StructField, StructType}
 
 abstract class QueryPlan[PlanType <: TreeNode[PlanType]] extends TreeNode[PlanType] {
-  self: PlanType with Product =>
+  self: PlanType =>
 
   def output: Seq[Attribute]
 

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

@@ -25,7 +25,7 @@ import org.apache.spark.sql.catalyst.plans.QueryPlan
 import org.apache.spark.sql.catalyst.trees.TreeNode
 
 
-abstract class LogicalPlan extends QueryPlan[LogicalPlan] with Logging with Product{
+abstract class LogicalPlan extends QueryPlan[LogicalPlan] with Logging {
 
   /**
    * Computes [[Statistics]] for this plan. The default implementation assumes the output

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/trees/TreeNode.scala

@@ -54,8 +54,8 @@ object CurrentOrigin {
   }
 }
 
-abstract class TreeNode[BaseType <: TreeNode[BaseType]] {
-  self: BaseType with Product =>
+abstract class TreeNode[BaseType <: TreeNode[BaseType]] extends Product {
+  self: BaseType =>
 
   val origin: Origin = CurrentOrigin.get
 

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

@@ -39,7 +39,7 @@ object SparkPlan {
  * :: DeveloperApi ::
  */
 @DeveloperApi
-abstract class SparkPlan extends QueryPlan[SparkPlan] with Logging with Product with Serializable {
+abstract class SparkPlan extends QueryPlan[SparkPlan] with Logging with Serializable {
 
   /**
    * A handle to the SQL Context that was used to create this plan.   Since many operators need