[CALCITE-7562] SqlToRel misses CAST in case IN expression without type coercion

core/src/main/java/org/apache/calcite/sql2rel/SqlToRelConverter.java

@@ -1870,7 +1870,7 @@ public RelNode convertToSingleValueSubq(
       if (leftKeys.size() == 1) {
         SqlCall sqlCall =
             comparisonOp.createCall(rightVals.getParserPosition(), leftKeys.get(0), rightVals);
-        rexComparison = bb.convertExpression(sqlCall);
+        rexComparison = ensureComparisonTypes(bb.convertExpression(sqlCall));
       } else {
         assert rightVals instanceof SqlCall;
         final SqlBasicCall call = (SqlBasicCall) rightVals;
@@ -1880,9 +1880,10 @@ public RelNode convertToSingleValueSubq(
             RexUtil.composeConjunction(rexBuilder,
                 transform(
                   Pair.zip(leftKeys, call.getOperandList()),
-                  pair -> bb.convertExpression(
-                        comparisonOp.createCall(rightVals.getParserPosition(),
-                            pair.left, pair.right))));
+                  pair -> ensureComparisonTypes(
+                      bb.convertExpression(
+                          comparisonOp.createCall(rightVals.getParserPosition(),
+                              pair.left, pair.right)))));
       }
       comparisons.add(rexComparison);
     }
@@ -1901,6 +1902,31 @@ public RelNode convertToSingleValueSubq(
     }
   }
 
+  /**
+   * Ensures that a comparison expression has matching operand types. If the
+   * operands have different type names, casts the right operand to match the
+   * left operand's type. This handles the case where type coercion is disabled
+   * and the IN-to-OR expansion produces comparisons with mismatched types
+   * (e.g., DATE = CHAR).
+   */
+  private RexNode ensureComparisonTypes(RexNode node) {
+    if (validator != null && validator.config().typeCoercionEnabled()) {
+      return node;
+    }
+    if (node instanceof RexCall) {
+      final RexCall call = (RexCall) node;
+      if (call.operands.size() == 2) {
+        final RexNode left = call.operands.get(0);
+        final RexNode right = call.operands.get(1);
+        if (left.getType().getSqlTypeName() != right.getType().getSqlTypeName()) {
+          final RexNode castRight = rexBuilder.ensureType(left.getType(), right, true);
+          return rexBuilder.makeCall(call.getOperator(), left, castRight);
+        }
+      }
+    }
+    return node;
+  }
+
   /**
    * Converts a {@link SqlNodeList} (for example an IN-list or VALUES list)
    * into a relational expression and produces a Rex-level sub-query that

core/src/test/java/org/apache/calcite/test/SqlToRelConverterTest.java

@@ -2213,6 +2213,24 @@ void checkCorrelatedMapSubQuery(boolean expand) {
     sql(sql).withExpand(false).ok();
   }
 
+  /** Test case for
+   * <a href="https://issues.apache.org/jira/browse/CALCITE-7562">[CALCITE-7562]
+   * SqlToRel misses CAST in case IN expression without type coercion</a>. */
+  @Test void testInDateColumnWithoutTypeCoercion() {
+    final String sql =
+        "select * from emp_b where birthdate in ('2000-06-30', '2000-09-27')";
+    sql(sql).withTypeCoercion(false).ok();
+  }
+
+  /** Test case for
+   * <a href="https://issues.apache.org/jira/browse/CALCITE-7562">[CALCITE-7562]
+   * SqlToRel misses CAST in case IN expression without type coercion</a>. */
+  @Test void testInDateColumnWithTypeCoercion() {
+    final String sql =
+        "select * from emp_b where birthdate in ('2000-06-30', '2000-09-27')";
+    sql(sql).ok();
+  }
+
   @Test void testInValueListLong() {
     // Go over the default threshold of 20 to force a sub-query.
     final String sql = "select empno from emp where deptno in"

core/src/test/resources/org/apache/calcite/test/SqlToRelConverterTest.xml

@@ -3266,6 +3266,30 @@ LogicalFilter(condition=[=($cor0.DEPTNO, $7)])
     LogicalAggregate(group=[{0}], S=[SUM($1)], agg#1=[COUNT()])
       LogicalProject(DEPTNO=[$7], SAL=[$5])
         LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+]]>
+    </Resource>
+  </TestCase>
+  <TestCase name="testInDateColumnWithTypeCoercion">
+    <Resource name="sql">
+      <![CDATA[select * from emp_b where birthdate in ('2000-06-30', '2000-09-27')]]>
+    </Resource>
+    <Resource name="plan">
+      <![CDATA[
+LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8], BIRTHDATE=[$9])
+  LogicalFilter(condition=[OR(=($9, CAST('2000-06-30'):DATE NOT NULL), =($9, CAST('2000-09-27'):DATE NOT NULL))])
+    LogicalTableScan(table=[[CATALOG, SALES, EMP_B]])
+]]>
+    </Resource>
+  </TestCase>
+  <TestCase name="testInDateColumnWithoutTypeCoercion">
+    <Resource name="sql">
+      <![CDATA[select * from emp_b where birthdate in ('2000-06-30', '2000-09-27')]]>
+    </Resource>
+    <Resource name="plan">
+      <![CDATA[
+LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8], BIRTHDATE=[$9])
+  LogicalFilter(condition=[OR(=($9, CAST('2000-06-30'):DATE NOT NULL), =($9, CAST('2000-09-27'):DATE NOT NULL))])
+    LogicalTableScan(table=[[CATALOG, SALES, EMP_B]])
 ]]>
     </Resource>
   </TestCase>

testkit/src/main/java/org/apache/calcite/test/SqlToRelFixture.java

@@ -178,6 +178,11 @@ public SqlToRelFixture withConformance(SqlConformance conformance) {
             .withValidatorConfig(c -> c.withConformance(conformance)));
   }
 
+  public SqlToRelFixture withTypeCoercion(boolean enabled) {
+    return withFactory(f ->
+        f.withValidatorConfig(c -> c.withTypeCoercionEnabled(enabled)));
+  }
+
   public SqlToRelFixture withDiffRepos(DiffRepository diffRepos) {
     return new SqlToRelFixture(sql, decorrelate, tester, factory, trim,
         expression, diffRepos);