[SPARK-31503][SQL][2.4] fix the SQL string of the TRIM functions

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

@@ -569,11 +569,22 @@ case class FindInSet(left: Expression, right: Expression) extends BinaryExpressi
 
 trait String2TrimExpression extends Expression with ImplicitCastInputTypes {
 
+  protected def srcStr: Expression
+  protected def trimStr: Option[Expression]
+
+  override def children: Seq[Expression] = srcStr +: trimStr.toSeq
   override def dataType: DataType = StringType
   override def inputTypes: Seq[AbstractDataType] = Seq.fill(children.size)(StringType)
 
   override def nullable: Boolean = children.exists(_.nullable)
   override def foldable: Boolean = children.forall(_.foldable)
+
+  // To match the actual parameter order.
+  override def sql: String = if (trimStr.isDefined) {
+    s"$prettyName(${trimStr.get.sql}, ${srcStr.sql})"
+  } else {
+    super.sql
+  }
 }
 
 object StringTrim {
@@ -641,11 +652,6 @@ case class StringTrim(
 
   override def prettyName: String = "trim"
 
-  override def children: Seq[Expression] = if (trimStr.isDefined) {
-    srcStr :: trimStr.get :: Nil
-  } else {
-    srcStr :: Nil
-  }
   override def eval(input: InternalRow): Any = {
     val srcString = srcStr.eval(input).asInstanceOf[UTF8String]
     if (srcString == null) {
@@ -741,12 +747,6 @@ case class StringTrimLeft(
 
   override def prettyName: String = "ltrim"
 
-  override def children: Seq[Expression] = if (trimStr.isDefined) {
-    srcStr :: trimStr.get :: Nil
-  } else {
-    srcStr :: Nil
-  }
-
   override def eval(input: InternalRow): Any = {
     val srcString = srcStr.eval(input).asInstanceOf[UTF8String]
     if (srcString == null) {
@@ -844,12 +844,6 @@ case class StringTrimRight(
 
   override def prettyName: String = "rtrim"
 
-  override def children: Seq[Expression] = if (trimStr.isDefined) {
-    srcStr :: trimStr.get :: Nil
-  } else {
-    srcStr :: Nil
-  }
-
   override def eval(input: InternalRow): Any = {
     val srcString = srcStr.eval(input).asInstanceOf[UTF8String]
     if (srcString == null) {

sql/core/src/test/resources/sql-tests/inputs/string-functions.sql

@@ -46,4 +46,8 @@ FROM (
     encode(string(id + 2), 'utf-8') col3,
     encode(string(id + 3), 'utf-8') col4
   FROM range(10)
-)
+);
+
+-- trim
+SELECT trim(" xyz "), ltrim(" xyz "), rtrim(" xyz ");
+SELECT trim('xyz', 'yxTomxx'), ltrim('xyz', 'yxTomxx'), rtrim('xyz', 'yxTomxx');

sql/core/src/test/resources/sql-tests/results/string-functions.sql.out

@@ -1,5 +1,5 @@
 -- Automatically generated by SQLQueryTestSuite
--- Number of queries: 15
+-- Number of queries: 17
 
 
 -- !query 0
@@ -161,3 +161,19 @@ struct<plan:string>
 == Physical Plan ==
 *Project [concat(cast(id#xL as string), cast(encode(cast((id#xL + 2) as string), utf-8) as string), cast(encode(cast((id#xL + 3) as string), utf-8) as string)) AS col#x]
 +- *Range (0, 10, step=1, splits=2)
+
+
+-- !query 15
+SELECT trim(" xyz "), ltrim(" xyz "), rtrim(" xyz ")
+-- !query 15 schema
+struct<trim( xyz ):string,ltrim( xyz ):string,rtrim( xyz ):string>
+-- !query 15 output
+xyz	xyz 	 xyz
+
+
+-- !query 16
+SELECT trim('xyz', 'yxTomxx'), ltrim('xyz', 'yxTomxx'), rtrim('xyz', 'yxTomxx')
+-- !query 16 schema
+struct<trim(xyz, yxTomxx):string,ltrim(xyz, yxTomxx):string,rtrim(xyz, yxTomxx):string>
+-- !query 16 output
+Tom	Tomxx	yxTom