[SPARK-33549][SQL] Remove configuration spark.sql.legacy.allowCastNum…

…ericToTimestamp

### What changes were proposed in this pull request?

Remove SQL configuration spark.sql.legacy.allowCastNumericToTimestamp

### Why are the changes needed?

In the current master branch, there is a new configuration `spark.sql.legacy.allowCastNumericToTimestamp` which controls whether to cast Numeric types to Timestamp or not. The default value is true.

After #30260, the type conversion between Timestamp type and Numeric type is disallowed in ANSI mode. So, we don't need to a separate configuration `spark.sql.legacy.allowCastNumericToTimestamp` for disallowing the conversion. Users just need to set `spark.sql.ansi.enabled` for the behavior.

As the configuration is not in any released yet, we should remove the configuration to make things simpler.

### Does this PR introduce _any_ user-facing change?

No, since the configuration is not released yet.

### How was this patch tested?

Existing test cases

Closes #30493 from gengliangwang/LEGACY_ALLOW_CAST_NUMERIC_TO_TIMESTAMP.

Authored-by: Gengliang Wang <gengliang.wang@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>

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

@@ -59,8 +59,7 @@ object Cast {
     case (StringType, TimestampType) => true
     case (BooleanType, TimestampType) => true
     case (DateType, TimestampType) => true
-    case (_: NumericType, TimestampType) =>
-      SQLConf.get.getConf(SQLConf.LEGACY_ALLOW_CAST_NUMERIC_TO_TIMESTAMP)
+    case (_: NumericType, TimestampType) => true
 
     case (StringType, DateType) => true
     case (TimestampType, DateType) => true
@@ -273,15 +272,7 @@ abstract class CastBase extends UnaryExpression with TimeZoneAwareExpression wit
       TypeCheckResult.TypeCheckSuccess
     } else {
       TypeCheckResult.TypeCheckFailure(
-        if (child.dataType.isInstanceOf[NumericType] && dataType.isInstanceOf[TimestampType]) {
-          s"cannot cast ${child.dataType.catalogString} to ${dataType.catalogString}," +
-            "you can enable the casting by setting " +
-            s"${SQLConf.LEGACY_ALLOW_CAST_NUMERIC_TO_TIMESTAMP.key} to true," +
-            "but we strongly recommend using function " +
-            "TIMESTAMP_SECONDS/TIMESTAMP_MILLIS/TIMESTAMP_MICROS instead."
-        } else {
-          s"cannot cast ${child.dataType.catalogString} to ${dataType.catalogString}"
-        })
+        s"cannot cast ${child.dataType.catalogString} to ${dataType.catalogString}")
     }
   }
 

sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala

@@ -2824,15 +2824,6 @@ object SQLConf {
       .checkValue(_ > 0, "The timeout value must be positive")
       .createWithDefault(10L)
 
-  val LEGACY_ALLOW_CAST_NUMERIC_TO_TIMESTAMP =
-    buildConf("spark.sql.legacy.allowCastNumericToTimestamp")
-      .internal()
-      .doc("When true, allow casting numeric to timestamp," +
-        "when false, forbid the cast, more details in SPARK-31710")
-      .version("3.1.0")
-      .booleanConf
-      .createWithDefault(true)
-
   val COALESCE_BUCKETS_IN_JOIN_ENABLED =
     buildConf("spark.sql.bucketing.coalesceBucketsInJoin.enabled")
       .doc("When true, if two bucketed tables with the different number of buckets are joined, " +
@@ -3550,9 +3541,6 @@ class SQLConf extends Serializable with Logging {
 
   def integerGroupingIdEnabled: Boolean = getConf(SQLConf.LEGACY_INTEGER_GROUPING_ID)
 
-  def legacyAllowCastNumericToTimestamp: Boolean =
-    getConf(SQLConf.LEGACY_ALLOW_CAST_NUMERIC_TO_TIMESTAMP)
-
   def metadataCacheTTL: Long = getConf(StaticSQLConf.METADATA_CACHE_TTL_SECONDS)
 
   def coalesceBucketsInJoinEnabled: Boolean = getConf(SQLConf.COALESCE_BUCKETS_IN_JOIN_ENABLED)

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

@@ -1311,20 +1311,6 @@ class CastSuite extends CastSuiteBase {
     }
   }
 
-  test("SPARK-31710: fail casting from numeric to timestamp if it is forbidden") {
-    Seq(true, false).foreach { enable =>
-      withSQLConf(SQLConf.LEGACY_ALLOW_CAST_NUMERIC_TO_TIMESTAMP.key -> enable.toString) {
-        assert(cast(2.toByte, TimestampType).resolved == enable)
-        assert(cast(10.toShort, TimestampType).resolved == enable)
-        assert(cast(3, TimestampType).resolved == enable)
-        assert(cast(10L, TimestampType).resolved == enable)
-        assert(cast(Decimal(1.2), TimestampType).resolved == enable)
-        assert(cast(1.7f, TimestampType).resolved == enable)
-        assert(cast(2.3d, TimestampType).resolved == enable)
-      }
-    }
-  }
-
   test("SPARK-32828: cast from a derived user-defined type to a base type") {
     val v = Literal.create(Row(1), new ExampleSubTypeUDT())
     checkEvaluation(cast(v, new ExampleBaseTypeUDT), Row(1))

sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/HiveCompatibilitySuite.scala

@@ -40,8 +40,6 @@ class HiveCompatibilitySuite extends HiveQueryFileTest with BeforeAndAfter {
   private val originalInMemoryPartitionPruning = TestHive.conf.inMemoryPartitionPruning
   private val originalCrossJoinEnabled = TestHive.conf.crossJoinEnabled
   private val originalSessionLocalTimeZone = TestHive.conf.sessionLocalTimeZone
-  private val originalLegacyAllowCastNumericToTimestamp =
-    TestHive.conf.legacyAllowCastNumericToTimestamp
 
   def testCases: Seq[(String, File)] = {
     hiveQueryDir.listFiles.map(f => f.getName.stripSuffix(".q") -> f)
@@ -61,8 +59,6 @@ class HiveCompatibilitySuite extends HiveQueryFileTest with BeforeAndAfter {
     // Fix session local timezone to America/Los_Angeles for those timezone sensitive tests
     // (timestamp_*)
     TestHive.setConf(SQLConf.SESSION_LOCAL_TIMEZONE, "America/Los_Angeles")
-    // Ensures that cast numeric to timestamp enabled so that we can test them
-    TestHive.setConf(SQLConf.LEGACY_ALLOW_CAST_NUMERIC_TO_TIMESTAMP, true)
     RuleExecutor.resetMetrics()
   }
 
@@ -73,8 +69,6 @@ class HiveCompatibilitySuite extends HiveQueryFileTest with BeforeAndAfter {
       TestHive.setConf(SQLConf.IN_MEMORY_PARTITION_PRUNING, originalInMemoryPartitionPruning)
       TestHive.setConf(SQLConf.CROSS_JOINS_ENABLED, originalCrossJoinEnabled)
       TestHive.setConf(SQLConf.SESSION_LOCAL_TIMEZONE, originalSessionLocalTimeZone)
-      TestHive.setConf(SQLConf.LEGACY_ALLOW_CAST_NUMERIC_TO_TIMESTAMP,
-        originalLegacyAllowCastNumericToTimestamp)
 
       // For debugging dump some statistics about how much time was spent in various optimizer rules
       logWarning(RuleExecutor.dumpTimeSpent())