[fix](function) allow count distinct on array

fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/agg/Count.java

@@ -92,7 +92,7 @@ public void checkLegalityBeforeTypeCoercion() {
     public void checkLegalityAfterRewrite() {
         // after rewrite, count(distinct bitmap_column) should be rewritten to bitmap_union_count(bitmap_column)
         for (Expression argument : getArguments()) {
-            if (distinct && (argument.getDataType().isComplexType()
+            if (distinct && ((argument.getDataType().isComplexType() && !argument.getDataType().isArrayType())
                     || argument.getDataType().isObjectType() || argument.getDataType().isJsonType())) {
                 throw new AnalysisException("COUNT DISTINCT could not process type " + this.toSql());
             }

fe/fe-core/src/test/java/org/apache/doris/nereids/rules/analysis/CheckExpressionLegalityTest.java

@@ -35,6 +35,7 @@
 import org.apache.doris.qe.ConnectContext;
 
 import com.google.common.collect.ImmutableList;
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
 import java.util.List;
@@ -81,6 +82,16 @@ public void testCountDistinctBitmap() {
         );
     }
 
+    @Test
+    public void testCountDistinctArray() {
+        ConnectContext connectContext = MemoTestUtils.createConnectContext();
+        String sql = "select count(distinct arr) from (select [1, 2] arr) tbl";
+        Assertions.assertDoesNotThrow(() -> PlanChecker.from(connectContext)
+                .analyze(sql)
+                .applyBottomUp(new ExpressionRewrite(CheckLegalityAfterRewrite.INSTANCE))
+        );
+    }
+
     @Test
     public void testWindowFunnelV2TooManyConditions() {
         List<Expression> arguments = ImmutableList.<Expression>builder()

regression-test/data/query_p0/aggregate/count_distinct_array.out

@@ -0,0 +1,7 @@
+-- This file is automatically generated. You should know what you did if you want to edit this
+-- !literal --
+2
+
+-- !nullable --
+2
+

regression-test/suites/query_p0/aggregate/count_distinct_array.groovy

@@ -0,0 +1,45 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+suite("count_distinct_array") {
+    sql "set enable_nereids_planner=true"
+    sql "set enable_fallback_to_original_planner=false"
+
+    qt_literal """
+        select count(distinct arr)
+        from (
+            select [1, 2] as arr
+            union all
+            select [1, 2]
+            union all
+            select [2, 1]
+        ) t
+    """
+
+    qt_nullable """
+        select count(distinct arr)
+        from (
+            select cast(null as array<int>) as arr
+            union all
+            select [1, 2]
+            union all
+            select [1, 2]
+            union all
+            select [2, 1]
+        ) t
+    """
+}

regression-test/suites/query_p0/sql_functions/aggregate_functions/test_count_distinct_with_collection_type.groovy

@@ -16,7 +16,7 @@
 // under the License.
 
 suite("test_count_distinct_with_collection_type", "p0") {
-    // not support array/map/struct
+    // array is supported now, map/struct are still unsupported
     sql " drop table if exists test_collection_type;"
     sql """ CREATE TABLE IF NOT EXISTS `test_collection_type` (
       `id` int(11) NULL,
@@ -37,29 +37,32 @@ suite("test_count_distinct_with_collection_type", "p0") {
     "enable_single_replica_compaction" = "false"
     ); """
 
-        test {
-            sql"""select count(distinct a) from test_collection_type;"""
-            check{result, exception, startTime, endTime ->
-                assertTrue(exception != null)
-                logger.info(exception.message)
-            }
-        }
-
-        test {
-            sql"""select count(distinct m) from test_collection_type;"""
-            check{result, exception, startTime, endTime ->
-                assertTrue(exception != null)
-                logger.info(exception.message)
-            }
-        }
-
-        test {
-            sql"""select count(distinct s) from test_collection_type;"""
-            check{result, exception, startTime, endTime ->
-                assertTrue(exception != null)
-                logger.info(exception.message)
-            }
+    test {
+        sql """
+            select count(distinct arr)
+            from (
+                select [1, 2] as arr
+                union all
+                select [1, 2]
+                union all
+                select [2, 1]
+                union all
+                select cast(null as array<int>)
+            ) t
+        """
+        check { result, exception, startTime, endTime ->
+            assertTrue(exception == null)
+            assertEquals(2, result[0][0])
         }
+    }
 
+    test {
+        sql """select count(distinct m) from test_collection_type;"""
+        exception "COUNT DISTINCT could not process type"
+    }
 
+    test {
+        sql """select count(distinct s) from test_collection_type;"""
+        exception "COUNT DISTINCT could not process type"
+    }
 }