Support tuples of heterogeneous types for empty expanding IN

Pass a list of all the types for the left side of an
IN expression to the visit_empty_set_expr() method, so that
the "empty expanding IN" can produce clauses for each element.

Fixes: #4271
Change-Id: I2738b9df2292ac01afda37f16d4fa56ae7bf9147

3 files changed, 21 insertions, 2 deletions

diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index 2f68b7e2e..27ee4afc6 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -1056,7 +1056,7 @@ class SQLCompiler(Compiled):
                 self._emit_empty_in_warning()
             return self.process(binary.left == binary.left)
 
-    def visit_empty_set_expr(self, type_):
+    def visit_empty_set_expr(self, element_types):
         raise NotImplementedError(
             "Dialect '%s' does not support empty set expression." %
             self.dialect.name
diff --git a/lib/sqlalchemy/sql/default_comparator.py b/lib/sqlalchemy/sql/default_comparator.py
index 5d02f65a1..8149f9731 100644
--- a/lib/sqlalchemy/sql/default_comparator.py
+++ b/lib/sqlalchemy/sql/default_comparator.py
@@ -15,7 +15,8 @@ from .elements import BindParameter, True_, False_, BinaryExpression, \
     Null, _const_expr, _clause_element_as_expr, \
     ClauseList, ColumnElement, TextClause, UnaryExpression, \
     collate, _is_literal, _literal_as_text, ClauseElement, and_, or_, \
-    Slice, Visitable, _literal_as_binds, CollectionAggregate
+    Slice, Visitable, _literal_as_binds, CollectionAggregate, \
+    Tuple
 from .selectable import SelectBase, Alias, Selectable, ScalarSelect
 
 
@@ -145,6 +146,14 @@ def _in_impl(expr, op, seq_or_selectable, negate_op, **kw):
     elif isinstance(seq_or_selectable, ClauseElement):
         if isinstance(seq_or_selectable, BindParameter) and \
                 seq_or_selectable.expanding:
+
+            if isinstance(expr, Tuple):
+                seq_or_selectable = (
+                    seq_or_selectable._with_expanding_in_types(
+                        [elem.type for elem in expr]
+                    )
+                )
+
             return _boolean_compare(
                 expr, op,
                 seq_or_selectable,
diff --git a/lib/sqlalchemy/sql/elements.py b/lib/sqlalchemy/sql/elements.py
index dd16b6862..de3b7992a 100644
--- a/lib/sqlalchemy/sql/elements.py
+++ b/lib/sqlalchemy/sql/elements.py
@@ -865,6 +865,7 @@ class BindParameter(ColumnElement):
     __visit_name__ = 'bindparam'
 
     _is_crud = False
+    _expanding_in_types = ()
 
     def __init__(self, key, value=NO_ARG, type_=None,
                  unique=False, required=NO_ARG,
@@ -1134,6 +1135,15 @@ class BindParameter(ColumnElement):
         else:
             self.type = type_
 
+    def _with_expanding_in_types(self, types):
+        """Return a copy of this :class:`.BindParameter` in
+        the context of an expanding IN against a tuple.
+
+        """
+        cloned = self._clone()
+        cloned._expanding_in_types = types
+        return cloned
+
     def _with_value(self, value):
         """Return a copy of this :class:`.BindParameter` with the given value
         set.