- Fixed bug where :meth:`.in_()` would go into an endless loop if

erroneously passed a column expression whose comparator included
the ``__getitem__()`` method, such as a column that uses the
:class:`.postgresql.ARRAY` type. [ticket:2957]

1 files changed, 7 insertions, 3 deletions

diff --git a/lib/sqlalchemy/sql/default_comparator.py b/lib/sqlalchemy/sql/default_comparator.py
index c39dce9c6..6d595450b 100644
--- a/lib/sqlalchemy/sql/default_comparator.py
+++ b/lib/sqlalchemy/sql/default_comparator.py
@@ -13,7 +13,7 @@ from . import type_api
 from .elements import BindParameter, True_, False_, BinaryExpression, \
         Null, _const_expr, _clause_element_as_expr, \
         ClauseList, ColumnElement, TextClause, UnaryExpression, \
-        collate, _is_literal, _literal_as_text
+        collate, _is_literal, _literal_as_text, ClauseElement
 from .selectable import SelectBase, Alias, Selectable, ScalarSelect
 
 class _DefaultColumnComparator(operators.ColumnOperators):
@@ -146,14 +146,18 @@ class _DefaultColumnComparator(operators.ColumnOperators):
         elif isinstance(seq_or_selectable, (Selectable, TextClause)):
             return self._boolean_compare(expr, op, seq_or_selectable,
                                   negate=negate_op, **kw)
+        elif isinstance(seq_or_selectable, ClauseElement):
+            raise exc.InvalidRequestError('in_() accepts'
+                    ' either a list of expressions '
+                    'or a selectable: %r' % seq_or_selectable)
 
         # Handle non selectable arguments as sequences
         args = []
         for o in seq_or_selectable:
             if not _is_literal(o):
                 if not isinstance(o, operators.ColumnOperators):
-                    raise exc.InvalidRequestError('in() function accept'
-                            's either a list of non-selectable values, '
+                    raise exc.InvalidRequestError('in_() accepts'
+                            ' either a list of expressions '
                             'or a selectable: %r' % o)
             elif o is None:
                 o = Null()