Tighten rules for order_by(Label) resolution

- Fixed bug originally introduced in 0.9 via :ticket:`1068` where
order_by(<some Label()>) would order by the label name based on name
alone, that is, even if the labeled expression were not at all the same
expression otherwise present, implicitly or explicitly, in the
selectable.  The logic that orders by label now ensures that the
labeled expression is related to the one that resolves to that name
before ordering by the label name; additionally, the name has to
resolve to an actual label explicit in the expression elsewhere, not
just a column name.  This logic is carefully kept separate from the
order by(textual name) feature that has a slightly different purpose.

Change-Id: I44fc36dab34380cc238c1e79ecbe23f1628d588a
Fixes: #3882

1 files changed, 6 insertions, 6 deletions

diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index b8c897cb9..f6f9fa45d 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -580,11 +580,11 @@ class SQLCompiler(Compiled):
         if self.stack and self.dialect.supports_simple_order_by_label:
             selectable = self.stack[-1]['selectable']
 
-            with_cols, only_froms = selectable._label_resolve_dict
+            with_cols, only_froms, only_cols = selectable._label_resolve_dict
             if within_columns_clause:
                 resolve_dict = only_froms
             else:
-                resolve_dict = with_cols
+                resolve_dict = only_cols
 
             # this can be None in the case that a _label_reference()
             # were subject to a replacement operation, in which case
@@ -593,11 +593,11 @@ class SQLCompiler(Compiled):
             order_by_elem = element.element._order_by_label_element
 
             if order_by_elem is not None and order_by_elem.name in \
-                    resolve_dict:
-
+                    resolve_dict and \
+                    order_by_elem.shares_lineage(
+                        resolve_dict[order_by_elem.name]):
                 kwargs['render_label_as_label'] = \
                     element.element._order_by_label_element
-
         return self.process(
             element.element, within_columns_clause=within_columns_clause,
             **kwargs)
@@ -611,7 +611,7 @@ class SQLCompiler(Compiled):
             )
 
         selectable = self.stack[-1]['selectable']
-        with_cols, only_froms = selectable._label_resolve_dict
+        with_cols, only_froms, only_cols = selectable._label_resolve_dict
         try:
             if within_columns_clause:
                 col = only_froms[element.element]