Tag GpuWindow child expressions for GPU execution

integration_tests/src/main/python/window_function_test.py

@@ -1108,4 +1108,43 @@ def test_window_first_last_nth_ignore_nulls(data_gen):
         lambda spark: three_col_df(spark, data_gen, string_gen, int_gen, num_slices=1).coalesce(1),
         "window_agg_table",
         'SELECT a, b, c, ' + exprs_for_nth_first_last_ignore_nulls +
-        'FROM window_agg_table')
+        'FROM window_agg_table')
+
+
+@ignore_order(local=True)
+def test_to_date_with_window_functions():
+    """
+    This test ensures that date expressions participating alongside window aggregations
+    are initialized correctly. (See: https://github.com/NVIDIA/spark-rapids/issues/5984)
+
+    For certain vendor-specific Spark versions, the date expression might be evaluated
+    directly in the WindowExec, instead of being projected upstream. For instance,
+    the query in this test might produce this plan on CPU:
+    ```
+      Window [cast(gettimestamp(cast(date_1#1 as string), yyyy-MM-dd, TimestampType, Some(Etc/UTC), false) as date)...]
+      +- Sort [id#0L ASC NULLS FIRST, date_2#2 ASC NULLS FIRST], false, 0
+         +- Exchange hashpartitioning(id#0L, 200), ENSURE_REQUIREMENTS, [id=#136]
+            +- *(1) Project [date_1#1, id#0L, date_2#2]
+    ```
+
+    This might trip up the GPU plan, by incompletely initializing `GpuGetTimeStamp` for `date_1` thus:
+    ```
+    +- GpuProject [cast(gpugettimestamp(cast(date_1#1 as string), yyyy-MM-dd, null, null, None) as date) AS my_date#6]
+    ```
+
+    The correct initialization should have yielded:
+    ```
+    +- GpuProject [cast(gpugettimestamp(cast(date_1#1 as string), yyyy-MM-dd, yyyy-MM-dd, %Y-%m-%d, None) as date)]
+    ```
+    """
+    assert_gpu_and_cpu_are_equal_sql(
+        df_fun=lambda spark: gen_df(spark, [('id', RepeatSeqGen(int_gen, 20)),
+                                            ('date_1', DateGen()),
+                                            ('date_2', DateGen())]),
+        table_name="window_input",
+        sql="""
+        SELECT TO_DATE( CAST(date_1 AS STRING), 'yyyy-MM-dd' ) AS my_date,
+               SUM(1) OVER(PARTITION BY id ORDER BY date_2) AS my_sum
+        FROM window_input
+        """
+    )

sql-plugin/src/main/scala/com/nvidia/spark/rapids/GpuWindowExec.scala

@@ -83,10 +83,15 @@ abstract class GpuBaseWindowExecMeta[WindowExecType <: SparkPlan] (windowExec: W
     getPartitionSpecs.map(GpuOverrides.wrapExpr(_, conf, Some(this)))
   val orderSpec: Seq[BaseExprMeta[SortOrder]] =
     getOrderSpecs.map(GpuOverrides.wrapExpr(_, conf, Some(this)))
-
   lazy val inputFields: Seq[BaseExprMeta[Attribute]] =
     windowExec.children.head.output.map(GpuOverrides.wrapExpr(_, conf, Some(this)))
 
+  /**
+   * Define all dependency expressions as `childExprs`.
+   * This ensures that they are tagged for GPU execution.
+   */
+  override val childExprs: Seq[BaseExprMeta[_]] =
+        windowExpressions ++ partitionSpec ++ orderSpec ++ inputFields
 
   override def namedChildExprs: Map[String, Seq[BaseExprMeta[_]]] = Map(
     "partitionSpec" -> partitionSpec