[CALCITE-7614] UNNEST of an unqualified struct-rooted array path fails validation: "Column 's.s' not found"

core/src/main/java/org/apache/calcite/sql/validate/DelegatingScope.java

@@ -329,6 +329,9 @@ protected void addColumnNames(
       final ResolvedImpl resolved = new ResolvedImpl();
       int size = identifier.names.size();
       int i = size - 1;
+      // Snapshot: resolution below may rewrite identifier's names in place [CALCITE-7614]
+      final SqlIdentifier identifierSnapshot =
+          (SqlIdentifier) identifier.clone(identifier.getParserPosition());
       for (; i > 0; i--) {
         final SqlIdentifier prefix = identifier.getComponent(0, i);
         resolved.clear();
@@ -388,7 +391,9 @@ protected void addColumnNames(
                 fromNs = resolve.namespace;
                 fromPath = resolve.path;
                 fromRowType = resolve.rowType();
-                identifier = identifier
+                // Qualify the original (pre-resolution) names; see the comment
+                // on identifierSnapshot above ([CALCITE-7614]).
+                identifier = identifierSnapshot
                     .setName(0, columnName)
                     .add(0, tableName2, SqlParserPos.ZERO);
                 ++i;

core/src/test/java/org/apache/calcite/sql/test/SqlAdvisorTest.java

@@ -96,6 +96,7 @@ class SqlAdvisorTest extends SqlValidatorTestCase {
           "TABLE(CATALOG.SALES.DOUBLE_PK)",
           "TABLE(CATALOG.SALES.DEPT_NESTED)",
           "TABLE(CATALOG.SALES.DEPT_NESTED_EXPANDED)",
+          "TABLE(CATALOG.SALES.DEPT_NESTED_PEEK)",
           "TABLE(CATALOG.SALES.BONUS)",
           "TABLE(CATALOG.SALES.ORDERS)",
           "TABLE(CATALOG.SALES.SALGRADE)",

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

@@ -9339,6 +9339,21 @@ void testGroupExpressionEquivalenceParams() {
     sql(sql3).fails("Table 'D' not found");
   }
 
+  /** Test case for
+   * <a href="https://issues.apache.org/jira/browse/CALCITE-7614">[CALCITE-7614]
+   * UNNEST of an array field in a PEEK_FIELDS struct column fails when the table
+   * is not qualified</a>. */
+  @Test void testUnnestPeekFieldsArrayColumn() {
+    // Table-qualified form already works.
+    sql("select * from dept_nested_peek as r CROSS JOIN UNNEST(r.s.arr) as x").ok();
+    // Unqualified form must work too (used to fail with
+    // "Column 'S.S' not found in table 'DEPT_NESTED_PEEK'").
+    sql("select * from dept_nested_peek CROSS JOIN UNNEST(s.arr) as x").ok();
+    // Comma-join variants, for parity with testUnnestArrayColumn.
+    sql("select * from dept_nested_peek as r, UNNEST(r.s.arr) as x").ok();
+    sql("select * from dept_nested_peek, UNNEST(s.arr) as x").ok();
+  }
+
   @Test void testUnnestWithOrdinality() {
     sql("select*from unnest(array[1, 2]) with ordinality")
         .type("RecordType(INTEGER NOT NULL EXPR$0, INTEGER NOT NULL ORDINALITY) NOT NULL");

testkit/src/main/java/org/apache/calcite/test/catalog/Fixture.java

@@ -136,6 +136,13 @@ final class Fixture extends AbstractFixture {
   final RelDataType varchar5ArrayType = array(varchar5Type);
   final RelDataType intArrayArrayType = array(intArrayType);
   final RelDataType varchar5ArrayArrayType = array(varchar5ArrayType);
+  // A "peek" struct that contains an array field, e.g. Row(ARR varchar(5) array)
+  // with StructKind.PEEK_FIELDS so that "ARR" can be referenced without the
+  // struct-column prefix.
+  final RelDataType peekArrayType = typeFactory.builder()
+      .add("ARR", varchar5ArrayType)
+      .kind(StructKind.PEEK_FIELDS)
+      .build();
   final RelDataType intMultisetType = typeFactory.createMultisetType(intType, -1);
   final RelDataType varchar5MultisetType = typeFactory.createMultisetType(varchar5Type, -1);
   final RelDataType intMultisetArrayType = array(intMultisetType);

testkit/src/main/java/org/apache/calcite/test/catalog/MockCatalogReaderSimple.java

@@ -177,6 +177,14 @@ private void registerTableDeptNestedExpanded(MockSchema salesSchema, Fixture fix
     registerTable(deptNestedExpandedTable);
   }
 
+  private void registerTableDeptNestedPeek(MockSchema salesSchema, Fixture fixture) {
+    MockTable deptNestedPeekTable =
+        MockTable.create(this, salesSchema, "DEPT_NESTED_PEEK", false, 4);
+    deptNestedPeekTable.addColumn("DEPTNO", fixture.intType, true);
+    deptNestedPeekTable.addColumn("S", fixture.peekArrayType);
+    registerTable(deptNestedPeekTable);
+  }
+
   private void registerTableBonus(MockSchema salesSchema, Fixture fixture) {
     MockTable bonusTable =
         MockTable.create(this, salesSchema, "BONUS", false, 0);
@@ -512,6 +520,10 @@ private void registerTableDoublePK(MockSchema salesSchema, Fixture fixture) {
     // Register "DEPT_NESTED_EXPANDED" table.
     registerTableDeptNestedExpanded(salesSchema, fixture);
 
+    // Register "DEPT_NESTED_PEEK" table, which has a PEEK_FIELDS struct column
+    // "S" containing an array field "ARR".
+    registerTableDeptNestedPeek(salesSchema, fixture);
+
     // Register "BONUS" table.
     registerTableBonus(salesSchema, fixture);