From d4881bb616d5ab4faa1f90df35befa307b738e9b Mon Sep 17 00:00:00 2001
From: caicancai <2356672992@qq.com>
Date: Fri, 1 Mar 2024 14:13:53 +0800
Subject: [PATCH] [CALCITE-5976] Use explicit casting if inserted element type
 in ArrayPrepend/ArrayAppend/ArrayInsert does not equal derived component type

---
 .../org/apache/calcite/sql/fun/SqlLibraryOperators.java    | 4 ++--
 .../org/apache/calcite/sql/validate/SqlValidatorUtil.java  | 7 +++++++
 .../main/java/org/apache/calcite/test/SqlOperatorTest.java | 6 +++---
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/core/src/main/java/org/apache/calcite/sql/fun/SqlLibraryOperators.java b/core/src/main/java/org/apache/calcite/sql/fun/SqlLibraryOperators.java
index 21685b884ff..06a8dab24f8 100644
--- a/core/src/main/java/org/apache/calcite/sql/fun/SqlLibraryOperators.java
+++ b/core/src/main/java/org/apache/calcite/sql/fun/SqlLibraryOperators.java
@@ -1187,7 +1187,7 @@ private static RelDataType arrayAppendPrependReturnType(SqlOperatorBinding opBin
     if (elementType.isNullable()) {
       type = opBinding.getTypeFactory().createTypeWithNullability(type, true);
     }
-    if (!componentType.equalsSansFieldNames(elementType)) {
+    if (!componentType.isNullable() && !componentType.equalsSansFieldNames(elementType)) {
       SqlValidatorUtil.
           adjustTypeForArrayFunctionConstructor(type, opBinding, 0);
       SqlValidatorUtil.
@@ -1280,7 +1280,7 @@ private static RelDataType arrayInsertReturnType(SqlOperatorBinding opBinding) {
       type = opBinding.getTypeFactory().createTypeWithNullability(type, true);
     }
 
-    if (!componentType.equalsSansFieldNames(elementType)) {
+    if (!componentType.isNullable() && !componentType.equalsSansFieldNames(elementType)) {
       SqlValidatorUtil.
           adjustTypeForArrayFunctionConstructor(type, opBinding, 0);
       SqlValidatorUtil.
diff --git a/core/src/main/java/org/apache/calcite/sql/validate/SqlValidatorUtil.java b/core/src/main/java/org/apache/calcite/sql/validate/SqlValidatorUtil.java
index d957c2ff737..9a36da34c3d 100644
--- a/core/src/main/java/org/apache/calcite/sql/validate/SqlValidatorUtil.java
+++ b/core/src/main/java/org/apache/calcite/sql/validate/SqlValidatorUtil.java
@@ -1327,6 +1327,13 @@ public static void adjustTypeForArrayConstructor(
     }
   }
 
+  /**
+   * When the array element does not equal the biggest type, make explicit casting.
+   *
+   * @param componentType derived array component type
+   * @param opBinding description of call
+   * @param index index of opBinding
+   */
   public static void adjustTypeForArrayFunctionConstructor(
       RelDataType componentType, SqlOperatorBinding opBinding, int index) {
     if (opBinding instanceof SqlCallBinding) {
diff --git a/testkit/src/main/java/org/apache/calcite/test/SqlOperatorTest.java b/testkit/src/main/java/org/apache/calcite/test/SqlOperatorTest.java
index 40b119eab9a..9a89d71e008 100644
--- a/testkit/src/main/java/org/apache/calcite/test/SqlOperatorTest.java
+++ b/testkit/src/main/java/org/apache/calcite/test/SqlOperatorTest.java
@@ -6341,7 +6341,7 @@ void checkRegexpExtract(SqlOperatorFixture f0, FunctionAlias functionAlias) {
     f.checkType("array_append(cast(null as integer array), 1)", "INTEGER NOT NULL ARRAY");
     f.checkFails("^array_append(array[1, 2], true)^",
         "INTEGER is not comparable to BOOLEAN", false);
-
+    // cast biggest type
     f.checkScalar("array_append(array(1), cast(2 as tinyint))", "[1, 2]",
         "INTEGER NOT NULL ARRAY NOT NULL");
     f.checkScalar("array_append(array(cast(1 as double)), cast(2 as float))", "[1.0, 2.0]",
@@ -6617,7 +6617,7 @@ void checkRegexpExtract(SqlOperatorFixture f0, FunctionAlias functionAlias) {
     f.checkType("array_prepend(cast(null as integer array), 1)", "INTEGER NOT NULL ARRAY");
     f.checkFails("^array_prepend(array[1, 2], true)^",
         "INTEGER is not comparable to BOOLEAN", false);
-
+    // cast biggest type
     f.checkScalar("array_prepend(array(1), cast(3 as float))", "[3.0, 1.0]",
         "FLOAT NOT NULL ARRAY NOT NULL");
     f.checkScalar("array_prepend(array(1), cast(3 as bigint))", "[3, 1]",
@@ -6922,7 +6922,7 @@ void checkRegexpExtract(SqlOperatorFixture f0, FunctionAlias functionAlias) {
         "(INTEGER NOT NULL, CHAR(1) NOT NULL) MAP NOT NULL ARRAY NOT NULL");
     f1.checkScalar("array_insert(array[map[1, 'a']], -1, map[2, 'b'])", "[{2=b}, {1=a}]",
         "(INTEGER NOT NULL, CHAR(1) NOT NULL) MAP NOT NULL ARRAY NOT NULL");
-
+    // cast biggest type
     f1.checkScalar("array_insert(array(1, 2, 3), 3, cast(4 as tinyint))",
         "[1, 2, 4, 3]", "INTEGER NOT NULL ARRAY NOT NULL");
     f1.checkScalar("array_insert(array(1, 2, 3), 3, cast(4 as double))",