[SPARK-51555][SQL][FOLLOWUP] Fix the error message for invalid unit in the time_diff() function

### What changes were proposed in this pull request?
Following up on the original PR that introduces the `time_diff` function (apache#51715), this PR fixes the error message to include the correct SQL function name.

### Why are the changes needed?
Fix error messages for the `time_diff` function.

### Does this PR introduce _any_ user-facing change?
Changes the error message for the new SQL function.

### How was this patch tested?
Updated relevant scala tests and golden files.

### Was this patch authored or co-authored using generative AI tooling?
No.

Closes apache#51777 from uros-db/time_diff_FOLLOWUP.

Authored-by: Uros Bojanic <[email protected]>
Signed-off-by: Wenchen Fan <[email protected]>

Author: uros-db

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/DateTimeUtils.scala

@@ -719,7 +719,7 @@ object DateTimeUtils extends SparkDateTimeUtils {
   // Helper method to get the number of nanoseconds per the given time unit, used for calculating
   // the difference between two time values (timediff function). Supported units are: MICROSECOND,
   // MILLISECOND, SECOND, MINUTE, HOUR.
-  private def getNanosPerTimeUnit(unit: UTF8String): Long = {
+  private def getNanosPerTimeUnit(unit: UTF8String, functionName: String): Long = {
     val unitStr = unit.toString
     unitStr.toUpperCase(Locale.ROOT) match {
       case "MICROSECOND" =>
@@ -733,7 +733,7 @@ object DateTimeUtils extends SparkDateTimeUtils {
       case "HOUR" =>
         NANOS_PER_SECOND * SECONDS_PER_MINUTE * MINUTES_PER_HOUR
       case _ =>
-        throw QueryExecutionErrors.invalidTimeUnitError("timediff", unitStr)
+        throw QueryExecutionErrors.invalidTimeUnitError(functionName, unitStr)
     }
   }
 
@@ -750,7 +750,7 @@ object DateTimeUtils extends SparkDateTimeUtils {
    * @return The time span between two time values, in the units specified.
    */
   def timeDiff(unit: UTF8String, startNanos: Long, endNanos: Long): Long = {
-    (endNanos - startNanos) / getNanosPerTimeUnit(unit)
+    (endNanos - startNanos) / getNanosPerTimeUnit(unit, "time_diff")
   }
 
   /**

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

@@ -423,7 +423,7 @@ class TimeExpressionsSuite extends SparkFunSuite with ExpressionEvalHelper {
         TimeDiff(Literal(unit), startTimeLit, endTimeLit),
         condition = "INVALID_PARAMETER_VALUE.TIME_UNIT",
         parameters = Map(
-          "functionName" -> "`timediff`",
+          "functionName" -> "`time_diff`",
           "parameter" -> "`unit`",
           "invalidValue" -> s"'$unit'"
         )

sql/core/src/test/resources/sql-tests/results/time.sql.out

@@ -1623,7 +1623,7 @@ org.apache.spark.SparkIllegalArgumentException
   "errorClass" : "INVALID_PARAMETER_VALUE.TIME_UNIT",
   "sqlState" : "22023",
   "messageParameters" : {
-    "functionName" : "`timediff`",
+    "functionName" : "`time_diff`",
     "invalidValue" : "''",
     "parameter" : "`unit`"
   }
@@ -1640,7 +1640,7 @@ org.apache.spark.SparkIllegalArgumentException
   "errorClass" : "INVALID_PARAMETER_VALUE.TIME_UNIT",
   "sqlState" : "22023",
   "messageParameters" : {
-    "functionName" : "`timediff`",
+    "functionName" : "`time_diff`",
     "invalidValue" : "' '",
     "parameter" : "`unit`"
   }
@@ -1657,7 +1657,7 @@ org.apache.spark.SparkIllegalArgumentException
   "errorClass" : "INVALID_PARAMETER_VALUE.TIME_UNIT",
   "sqlState" : "22023",
   "messageParameters" : {
-    "functionName" : "`timediff`",
+    "functionName" : "`time_diff`",
     "invalidValue" : "'MS'",
     "parameter" : "`unit`"
   }
@@ -1674,7 +1674,7 @@ org.apache.spark.SparkIllegalArgumentException
   "errorClass" : "INVALID_PARAMETER_VALUE.TIME_UNIT",
   "sqlState" : "22023",
   "messageParameters" : {
-    "functionName" : "`timediff`",
+    "functionName" : "`time_diff`",
     "invalidValue" : "'DAY'",
     "parameter" : "`unit`"
   }
@@ -1691,7 +1691,7 @@ org.apache.spark.SparkIllegalArgumentException
   "errorClass" : "INVALID_PARAMETER_VALUE.TIME_UNIT",
   "sqlState" : "22023",
   "messageParameters" : {
-    "functionName" : "`timediff`",
+    "functionName" : "`time_diff`",
     "invalidValue" : "'WEEK'",
     "parameter" : "`unit`"
   }
@@ -1708,7 +1708,7 @@ org.apache.spark.SparkIllegalArgumentException
   "errorClass" : "INVALID_PARAMETER_VALUE.TIME_UNIT",
   "sqlState" : "22023",
   "messageParameters" : {
-    "functionName" : "`timediff`",
+    "functionName" : "`time_diff`",
     "invalidValue" : "'ABCD'",
     "parameter" : "`unit`"
   }
@@ -1725,7 +1725,7 @@ org.apache.spark.SparkIllegalArgumentException
   "errorClass" : "INVALID_PARAMETER_VALUE.TIME_UNIT",
   "sqlState" : "22023",
   "messageParameters" : {
-    "functionName" : "`timediff`",
+    "functionName" : "`time_diff`",
     "invalidValue" : "'QUARTER'",
     "parameter" : "`unit`"
   }
@@ -1742,7 +1742,7 @@ org.apache.spark.SparkIllegalArgumentException
   "errorClass" : "INVALID_PARAMETER_VALUE.TIME_UNIT",
   "sqlState" : "22023",
   "messageParameters" : {
-    "functionName" : "`timediff`",
+    "functionName" : "`time_diff`",
     "invalidValue" : "'INVALID'",
     "parameter" : "`unit`"
   }
@@ -1759,7 +1759,7 @@ org.apache.spark.SparkIllegalArgumentException
   "errorClass" : "INVALID_PARAMETER_VALUE.TIME_UNIT",
   "sqlState" : "22023",
   "messageParameters" : {
-    "functionName" : "`timediff`",
+    "functionName" : "`time_diff`",
     "invalidValue" : "'INVALID_UNIT'",
     "parameter" : "`unit`"
   }