Fix: make traversing scopes more lenient

sqlglot/optimizer/scope.py

@@ -1,4 +1,5 @@
 import itertools
+import logging
 import typing as t
 from collections import defaultdict
 from enum import Enum, auto
@@ -7,6 +8,8 @@
 from sqlglot.errors import OptimizeError
 from sqlglot.helper import find_new_name
 
+logger = logging.getLogger("sqlglot")
+
 
 class ScopeType(Enum):
     ROOT = auto()
@@ -536,7 +539,11 @@ def _traverse_scope(scope):
     elif isinstance(scope.expression, exp.UDTF):
         pass
     else:
-        raise OptimizeError(f"Unexpected expression type: {type(scope.expression)}")
+        logger.warning(
+            "Cannot traverse scope %s with type '%s'", scope.expression, type(scope.expression)
+        )
+        return
+
     yield scope
 
 
@@ -576,6 +583,8 @@ def _traverse_ctes(scope):
             if isinstance(union, exp.Union):
                 recursive_scope = scope.branch(union.this, scope_type=ScopeType.CTE)
 
+        child_scope = None
+
         for child_scope in _traverse_scope(
             scope.branch(
                 cte.this,
@@ -593,7 +602,8 @@ def _traverse_ctes(scope):
                 child_scope.add_source(alias, recursive_scope)
 
         # append the final child_scope yielded
-        scope.cte_scopes.append(child_scope)
+        if child_scope:
+            scope.cte_scopes.append(child_scope)
 
     scope.sources.update(sources)
 
@@ -634,6 +644,9 @@ def _traverse_tables(scope):
                 sources[source_name] = expression
             continue
 
+        if not isinstance(expression, exp.DerivedTable):
+            continue
+
         if isinstance(expression, exp.UDTF):
             lateral_sources = sources
             scope_type = ScopeType.UDTF

tests/helpers.py

@@ -22,7 +22,9 @@ def _extract_meta(sql):
 
 def assert_logger_contains(message, logger, level="error"):
     output = "\n".join(str(args[0][0]) for args in getattr(logger, level).call_args_list)
-    assert message in output
+    if message not in output:
+        print(f"Expected '{message}' not in {output}")
+        raise
 
 
 def load_sql_fixtures(filename):

tests/test_optimizer.py

@@ -1,6 +1,7 @@
 import unittest
 from concurrent.futures import ProcessPoolExecutor, as_completed
 from functools import partial
+from unittest.mock import patch
 
 import duckdb
 from pandas.testing import assert_frame_equal
@@ -14,6 +15,7 @@
 from tests.helpers import (
     TPCDS_SCHEMA,
     TPCH_SCHEMA,
+    assert_logger_contains,
     load_sql_fixture_pairs,
     load_sql_fixtures,
     string_to_bool,
@@ -411,6 +413,15 @@ def test_scope(self):
             {"s.b"},
         )
 
+    @patch("sqlglot.optimizer.scope.logger")
+    def test_scope_warning(self, logger):
+        self.assertEqual(len(traverse_scope(parse_one("WITH q AS (@y) SELECT * FROM q"))), 1)
+        assert_logger_contains(
+            "Cannot traverse scope %s with type '%s'",
+            logger,
+            level="warning",
+        )
+
     def test_literal_type_annotation(self):
         tests = {
             "SELECT 5": exp.DataType.Type.INT,