Improve rendering of core statements w/ ORM elements

This patch contains a variety of ORM and expression layer
tweaks to support ORM constructs in select() statements,
without the 1.3.x requiremnt in Query that a full
_compile_context() + new select() is needed in order to
get a working statement object.

Includes such tweaks as the ability to implement
aliased class of an aliased class,
as we are looking to fully support ACs against subqueries,
as well as the ability to access anonymously-labeled
ColumnProperty expressions within subqueries by
naming the ".key" of the label after the property
key.   Some tuning to query.join() as well
as ORMJoin internals to allow things to work more
smoothly.

Change-Id: Id810f485c5f7ed971529489b84694e02a3356d6d

1 files changed, 18 insertions, 5 deletions

diff --git a/lib/sqlalchemy/sql/elements.py b/lib/sqlalchemy/sql/elements.py
index 287e53724..fa2888a23 100644
--- a/lib/sqlalchemy/sql/elements.py
+++ b/lib/sqlalchemy/sql/elements.py
@@ -878,6 +878,7 @@ class ColumnElement(
             key = self._proxy_key
         else:
             key = name
+
         co = ColumnClause(
             coercions.expect(roles.TruncatedLabelRole, name)
             if name_is_truncatable
@@ -885,6 +886,7 @@ class ColumnElement(
             type_=getattr(self, "type", None),
             _selectable=selectable,
         )
+
         co._propagate_attrs = selectable._propagate_attrs
         co._proxies = [self]
         if selectable._is_clone_of is not None:
@@ -1284,6 +1286,7 @@ class BindParameter(roles.InElementRole, ColumnElement):
 
 
         """
+
         if required is NO_ARG:
             required = value is NO_ARG and callable_ is None
         if value is NO_ARG:
@@ -1302,6 +1305,7 @@ class BindParameter(roles.InElementRole, ColumnElement):
                     id(self),
                     re.sub(r"[%\(\) \$]+", "_", key).strip("_")
                     if key is not None
+                    and not isinstance(key, _anonymous_label)
                     else "param",
                 )
             )
@@ -4182,16 +4186,27 @@ class Label(roles.LabeledColumnExprRole, ColumnElement):
         return self.element._from_objects
 
     def _make_proxy(self, selectable, name=None, **kw):
+        name = self.name if not name else name
+
         key, e = self.element._make_proxy(
             selectable,
-            name=name if name else self.name,
+            name=name,
             disallow_is_literal=True,
+            name_is_truncatable=isinstance(name, _truncated_label),
         )
+        # TODO: want to remove this assertion at some point.  all
+        # _make_proxy() implementations will give us back the key that
+        # is our "name" in the first place.  based on this we can
+        # safely return our "self.key" as the key here, to support a new
+        # case where the key and name are separate.
+        assert key == self.name
+
         e._propagate_attrs = selectable._propagate_attrs
         e._proxies.append(self)
         if self._type is not None:
             e.type = self._type
-        return key, e
+
+        return self.key, e
 
 
 class ColumnClause(
@@ -4240,7 +4255,7 @@ class ColumnClause(
     __visit_name__ = "column"
 
     _traverse_internals = [
-        ("name", InternalTraversal.dp_string),
+        ("name", InternalTraversal.dp_anon_name),
         ("type", InternalTraversal.dp_type),
         ("table", InternalTraversal.dp_clauseelement),
         ("is_literal", InternalTraversal.dp_boolean),
@@ -4410,10 +4425,8 @@ class ColumnClause(
 
     def _gen_label(self, name, dedupe_on_key=True):
         t = self.table
-
         if self.is_literal:
             return None
-
         elif t is not None and t.named_with_column:
             if getattr(t, "schema", None):
                 label = t.schema.replace(".", "_") + "_" + t.name + "_" + name