Fix aggregation filter expression processing in the absense of projection (#14893)

* test

* fix

* add 33 test

* crap

* Revert "crap"

This reverts commit 2751198deb.

* cleanup test

* celanup

* rename test

sql/src/main/java/org/apache/druid/sql/calcite/rule/GroupByRules.java

@@ -73,12 +73,13 @@ public class GroupByRules
 
     if (call.filterArg >= 0) {
       // AGG(xxx) FILTER(WHERE yyy)
-      if (project == null) {
-        // We need some kind of projection to support filtered aggregations.
-        return null;
-      }
 
-      final RexNode expression = project.getProjects().get(call.filterArg);
+      final RexNode expression = Expressions.fromFieldAccess(
+            rexBuilder.getTypeFactory(),
+            rowSignature,
+            project,
+            call.filterArg);
+
       final DimFilter nonOptimizedFilter = Expressions.toFilter(
           plannerContext,
           rowSignature,

sql/src/test/java/org/apache/druid/sql/calcite/CalciteSelectQueryTest.java

@@ -32,6 +32,7 @@ import org.apache.druid.query.LookupDataSource;
 import org.apache.druid.query.QueryDataSource;
 import org.apache.druid.query.aggregation.CountAggregatorFactory;
 import org.apache.druid.query.aggregation.DoubleSumAggregatorFactory;
+import org.apache.druid.query.aggregation.FilteredAggregatorFactory;
 import org.apache.druid.query.dimension.DefaultDimensionSpec;
 import org.apache.druid.query.extraction.SubstringDimExtractionFn;
 import org.apache.druid.query.groupby.GroupByQuery;
@@ -1923,4 +1924,26 @@ public class CalciteSelectQueryTest extends BaseCalciteQueryTest
         )
     );
   }
+
+  @Test
+  public void testAggregateFilterInTheAbsenceOfProjection()
+  {
+    cannotVectorize();
+    testQuery(
+        "select count(1) filter (where __time > date '2023-01-01') " +
+            " from druid.foo where 'a' = 'b'",
+        ImmutableList.of(
+            Druids.newTimeseriesQueryBuilder()
+                .dataSource(InlineDataSource.fromIterable(
+                    ImmutableList.of(),
+                    RowSignature.builder().add("$f1", ColumnType.LONG).build()))
+                .intervals(querySegmentSpec(Filtration.eternity()))
+                .granularity(Granularities.ALL)
+                .aggregators(aggregators(
+                    new FilteredAggregatorFactory(
+                        new CountAggregatorFactory("a0"), expressionFilter("\"$f1\""))))
+                .context(QUERY_CONTEXT_DEFAULT)
+                .build()),
+        ImmutableList.of(new Object[] {0L}));
+  }
 }