fix: fall back to Spark for MapSort with unsupported key types

Arrow's sort_to_indices does not support Struct (and other complex)
key types, so map_sort fails at runtime when the map key is a struct.
Check key type via supportedScalarSortElementType and fall back to
Spark when the key type is not natively sortable. This fixes 4
CollationSuite failures in spark-sql-auto-sql_core-1 for Spark 4.0:
'Group by on map containing structs with ...'.

Author: andygrove

spark/src/main/spark-4.0/org/apache/comet/shims/CometExprShim.scala

@@ -24,13 +24,13 @@ import org.apache.spark.sql.catalyst.expressions.json.StructsToJsonEvaluator
 import org.apache.spark.sql.catalyst.expressions.objects.{Invoke, StaticInvoke}
 import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.internal.types.StringTypeWithCollation
-import org.apache.spark.sql.types.{BinaryType, BooleanType, DataTypes, StringType}
+import org.apache.spark.sql.types.{BinaryType, BooleanType, DataTypes, MapType, StringType}
 
 import org.apache.comet.CometSparkSessionExtensions.withInfo
 import org.apache.comet.expressions.{CometCast, CometEvalMode}
 import org.apache.comet.serde.{CommonStringExprs, Compatible, ExprOuterClass, Incompatible}
 import org.apache.comet.serde.ExprOuterClass.{BinaryOutputStyle, Expr}
-import org.apache.comet.serde.QueryPlanSerde.{exprToProtoInternal, optExprWithInfo, scalarFunctionExprToProto, scalarFunctionExprToProtoWithReturnType}
+import org.apache.comet.serde.QueryPlanSerde.{exprToProtoInternal, optExprWithInfo, scalarFunctionExprToProto, scalarFunctionExprToProtoWithReturnType, supportedScalarSortElementType}
 
 /**
  * `CometExprShim` acts as a shim for parsing expressions from different Spark versions.
@@ -129,13 +129,19 @@ trait CometExprShim extends CommonStringExprs {
         }
 
       case ms: MapSort =>
-        val childExpr = exprToProtoInternal(ms.child, inputs, binding)
-        val mapSortExpr = scalarFunctionExprToProtoWithReturnType(
-          "map_sort",
-          ms.dataType,
-          failOnError = false,
-          childExpr)
-        optExprWithInfo(mapSortExpr, ms, ms.child)
+        val keyType = ms.dataType.asInstanceOf[MapType].keyType
+        if (!supportedScalarSortElementType(keyType)) {
+          withInfo(ms, s"MapSort on map with key type $keyType is not supported")
+          None
+        } else {
+          val childExpr = exprToProtoInternal(ms.child, inputs, binding)
+          val mapSortExpr = scalarFunctionExprToProtoWithReturnType(
+            "map_sort",
+            ms.dataType,
+            failOnError = false,
+            childExpr)
+          optExprWithInfo(mapSortExpr, ms, ms.child)
+        }
 
       case _ => None
     }