Ensure post-__clause_element__() expression are used in Index

The change in Index for 1.1 combined with the fix for
ref #3763 still fails to deliver the correct object
resolved by __clause_element__() to the list of expressions
for compilation.   Make sure we use the expression that's
been unwrapped from __clause_element__().

Change-Id: Ie1df8db5090de665048331786f0024d52851923f
Fixes: #3763

1 files changed, 14 insertions, 0 deletions

diff --git a/test/sql/test_metadata.py b/test/sql/test_metadata.py
index cf7f7628a..af291b842 100644
--- a/test/sql/test_metadata.py
+++ b/test/sql/test_metadata.py
@@ -2168,6 +2168,20 @@ class ConstraintTest(fixtures.TestBase):
 
         eq_(set(t.indexes), set([idx]))
 
+    def test_clauseelement_extraction_three(self):
+        t = Table('t', MetaData(), Column('x', Integer), Column('y', Integer))
+
+        expr1 = t.c.x + 5
+
+        class MyThing(object):
+            def __clause_element__(self):
+                return expr1
+
+        idx = Index('bar', MyThing(), t.c.y)
+
+        is_(idx.expressions[0], expr1)
+        is_(idx.expressions[1], t.c.y)
+
     def test_table_references(self):
         t1, t2, t3 = self._single_fixture()
         assert list(t2.c.a.foreign_keys)[0].references(t1)