[ESQL] Mark date_diff as requiring all three arguments (#108834) (#10…

…8874)

Resolves #108383

I didn't see a good place to add a test for this; if there is one, let me know and I'm happy to add it.

This fixes a bug where we had incorrectly marked date_diff as having an optional argument, which resulted in an NPE when that argument was not provided. In fact, all three of date_diff's arguments are required. After this change, failing to provide one will cause a parse exception, as one would expect.

docs/changelog/108834.yaml

@@ -0,0 +1,6 @@
+pr: 108834
+summary: "[ESQL] Mark `date_diff` as requiring all three arguments"
+area: ES|QL
+type: bug
+issues:
+ - 108383

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/date/DateDiff.java

@@ -16,7 +16,6 @@
 import org.elasticsearch.xpack.esql.expression.function.scalar.EsqlScalarFunction;
 import org.elasticsearch.xpack.ql.InvalidArgumentException;
 import org.elasticsearch.xpack.ql.expression.Expression;
-import org.elasticsearch.xpack.ql.expression.function.OptionalArgument;
 import org.elasticsearch.xpack.ql.tree.NodeInfo;
 import org.elasticsearch.xpack.ql.tree.Source;
 import org.elasticsearch.xpack.ql.type.DataType;
@@ -47,7 +46,7 @@
  * in multiples of the unit specified in the first argument.
  * If the second argument (start) is greater than the third argument (end), then negative values are returned.
  */
-public class DateDiff extends EsqlScalarFunction implements OptionalArgument {
+public class DateDiff extends EsqlScalarFunction {
 
     public static final ZoneId UTC = ZoneId.of("Z");