Ensure CTE internals are handled during clone

The CTE construct was missing a _copy_internals() method
which would handle CTE-specific structures including _cte_alias,
_restates during a clone operation.

Change-Id: I9aeac9cd24d8f7ae6b70e52650d61f7c96cb6d7e
Fixes: #3722

1 files changed, 17 insertions, 0 deletions

diff --git a/test/sql/test_generative.py b/test/sql/test_generative.py
index 9cf1ef612..81c589d11 100644
--- a/test/sql/test_generative.py
+++ b/test/sql/test_generative.py
@@ -475,6 +475,23 @@ class ClauseTest(fixtures.TestBase, AssertsCompiledSQL):
             "FROM table3 AS table3_1"
         )
 
+    def test_cte_w_union(self):
+        t = select([func.values(1).label("n")]).cte("t", recursive=True)
+        t = t.union_all(select([t.c.n + 1]).where(t.c.n < 100))
+        s = select([func.sum(t.c.n)])
+
+        from sqlalchemy.sql.visitors import cloned_traverse
+        cloned = cloned_traverse(s, {}, {})
+
+        self.assert_compile(cloned,
+                            "WITH RECURSIVE t(n) AS "
+                            "(SELECT values(:values_1) AS n "
+                            "UNION ALL SELECT t.n + :n_1 AS anon_1 "
+                            "FROM t "
+                            "WHERE t.n < :n_2) "
+                            "SELECT sum(t.n) AS sum_1 FROM t"
+                            )
+
     def test_text(self):
         clause = text(
             "select * from table where foo=:bar",