Adjustments to _copy_internals()

We are looking to build a generalization of copy_internals(),
so move out any special logic from these methods.   Re-implement
and clarify rationale for the Alias doesnt copy a TableClause rule as
part of the adaption
traversal, establish that we forgot to build out comparison and cache
key for CTE, remove incomplete _copy_internals() from GenerativeSelect
(it doesn't handle the order_by_clause or group_by_clause, so is incomplete)

Change-Id: I95039f042503171aade4ba0fabc9b1598e3c49cf

1 files changed, 19 insertions, 4 deletions

diff --git a/lib/sqlalchemy/sql/util.py b/lib/sqlalchemy/sql/util.py
index dd2c7c1fb..fe83b163c 100644
--- a/lib/sqlalchemy/sql/util.py
+++ b/lib/sqlalchemy/sql/util.py
@@ -806,10 +806,25 @@ class ClauseAdapter(visitors.ReplacingCloningVisitor):
         return newcol
 
     def replace(self, col):
-        if isinstance(col, FromClause) and self.selectable.is_derived_from(
-            col
-        ):
-            return self.selectable
+        if isinstance(col, FromClause):
+            if self.selectable.is_derived_from(col):
+                return self.selectable
+            elif isinstance(col, Alias) and isinstance(
+                col.element, TableClause
+            ):
+                # we are a SELECT statement and not derived from an alias of a
+                # table (which nonetheless may be a table our SELECT derives
+                # from), so return the alias to prevent futher traversal
+                # or
+                # we are an alias of a table and we are not derived from an
+                # alias of a table (which nonetheless may be the same table
+                # as ours) so, same thing
+                return col
+            else:
+                # other cases where we are a selectable and the element
+                # is another join or selectable that contains a table which our
+                # selectable derives from, that we want to process
+                return None
         elif not isinstance(col, ColumnElement):
             return None
         elif self.include_fn and not self.include_fn(col):