[CALCITE-2295] Correlated SubQuery with Project will generate error plan

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

@@ -9116,6 +9116,16 @@ public interface Config extends RelRule.Config {
         .check();
   }
 
+  /** Test case for
+   * <a href="https://issues.apache.org/jira/browse/CALCITE-2295">[CALCITE-2295]
+   * Correlated SubQuery with Project will generate error plan</a>. */
+  @Test public void testDecorrelationWithProject() throws Exception {
+    final String sql = "select sal,\n"
+        + "exists (select * from emp_b where emp.deptno = emp_b.deptno)\n"
+        + "from sales.emp";
+    sql(sql).withSubQueryRules().withLateDecorrelate(true).check();
+  }
+
   /** Test case for
    * <a href="https://issues.apache.org/jira/browse/CALCITE-3296">[CALCITE-3296]
    * Decorrelator gives empty result after decorrelating sort rel with

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

@@ -2483,6 +2483,44 @@ LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$
       LogicalAggregate(group=[{0}])
         LogicalProject(DEPTNO=[$7])
           LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+]]>
+    </Resource>
+  </TestCase>
+  <TestCase name="testDecorrelationWithProject">
+    <Resource name="sql">
+      <![CDATA[select sal,
+exists (select * from emp_b where emp.deptno = emp_b.deptno)
+from sales.emp]]>
+    </Resource>
+    <Resource name="planBefore">
+      <![CDATA[
+LogicalProject(variablesSet=[[$cor0]], SAL=[$5], EXPR$1=[EXISTS({
+LogicalFilter(condition=[=($cor0.DEPTNO, $7)])
+  LogicalTableScan(table=[[CATALOG, SALES, EMP_B]])
+})])
+  LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+]]>
+    </Resource>
+    <Resource name="planMid">
+      <![CDATA[
+LogicalProject(SAL=[$5], EXPR$1=[IS NOT NULL($9)])
+  LogicalCorrelate(correlation=[$cor0], joinType=[left], requiredColumns=[{7}])
+    LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+    LogicalAggregate(group=[{0}])
+      LogicalProject(i=[true])
+        LogicalFilter(condition=[=($cor0.DEPTNO, $7)])
+          LogicalTableScan(table=[[CATALOG, SALES, EMP_B]])
+]]>
+    </Resource>
+    <Resource name="planAfter">
+      <![CDATA[
+LogicalProject(SAL=[$5], EXPR$1=[IS NOT NULL($10)])
+  LogicalJoin(condition=[=($7, $9)], joinType=[left])
+    LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+    LogicalProject(DEPTNO=[$0], $f1=[true])
+      LogicalAggregate(group=[{0}])
+        LogicalProject(DEPTNO=[$7])
+          LogicalTableScan(table=[[CATALOG, SALES, EMP_B]])
 ]]>
     </Resource>
   </TestCase>