modify checkInputDataTypes using foldable

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

@@ -558,8 +558,8 @@ case class Round(child: Expression, scale: Expression) extends Expression {
           return TypeCheckFailure("ROUND scale argument out of allowed range")
         }
       case Literal(_, _: IntegralType) | Literal(_, NullType) => // satisfy requirement
-      case child =>
-        if (child.find { case _: AttributeReference => true; case _ => false } != None) {
+      case _ =>
+        if (!scale.foldable) {
           return TypeCheckFailure("Only Integral Literal or Null Literal " +
             s"are allowed for ROUND scale arguments, got ${child.dataType}")
         }
@@ -595,6 +595,21 @@ case class Round(child: Expression, scale: Expression) extends Expression {
     }
   }
 
+  private def round[T](input: T, scale: Int)(implicit bdc: BigDecimalConverter[T]): T = {
+    input match {
+      case f: Float if (f.isNaN || f.isInfinite) => return input
+      case d: Double if (d.isNaN || d.isInfinite) => return input
+      case _ =>
+    }
+    bdc.fromBigDecimal(bdc.toBigDecimal(input).setScale(scale, BigDecimal.RoundingMode.HALF_UP))
+  }
+
+  private def round(input: String, scale: Int): Any = {
+    try round(input.toDouble, scale) catch {
+      case _ : NumberFormatException => null
+    }
+  }
+
   override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode): String = {
     val ce = child.gen(ctx)
 
@@ -672,19 +687,4 @@ case class Round(child: Expression, scale: Expression) extends Expression {
       }
       """
   }
-
-  private def round[T](input: T, scale: Int)(implicit bdc: BigDecimalConverter[T]): T = {
-    input match {
-      case f: Float if (f.isNaN || f.isInfinite) => return input
-      case d: Double if (d.isNaN || d.isInfinite) => return input
-      case _ =>
-    }
-    bdc.fromBigDecimal(bdc.toBigDecimal(input).setScale(scale, BigDecimal.RoundingMode.HALF_UP))
-  }
-
-  private def round(input: String, scale: Int): Any = {
-    try round(input.toDouble, scale) catch {
-      case _ : NumberFormatException => null
-    }
-  }
 }

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

@@ -339,7 +339,7 @@ class MathFunctionsSuite extends SparkFunSuite with ExpressionEvalHelper {
       create_row(null))
   }
 
-  test("round test") {
+  test("round") {
     val domain = -16 to 16
     val doublePi = math.Pi
     val stringPi = "3.141592653589793"