deprecation warnings: strings in loader options, join, with_parent

Repairs one in-library deprecation warning regarding
mapper propagation of options

raises maxfail to 250, as 25 is too low when we are trying
to address many errors at once.   the 25 was originally
due to the fact that our fixtures would be broken after
that many failures in most cases, which today should not
be the case nearly as often.

Change-Id: I26affddf42e2cae2aaf9561633e9b8cd431eb189

1 files changed, 16 insertions, 3 deletions

diff --git a/lib/sqlalchemy/ext/associationproxy.py b/lib/sqlalchemy/ext/associationproxy.py
index 411033a6b..dd5c10ac9 100644
--- a/lib/sqlalchemy/ext/associationproxy.py
+++ b/lib/sqlalchemy/ext/associationproxy.py
@@ -472,10 +472,23 @@ class AssociationProxyInstance(object):
     def attr(self):
         """Return a tuple of ``(local_attr, remote_attr)``.
 
-        This attribute is convenient when specifying a join
-        using :meth:`_query.Query.join` across two relationships::
+        This attribute was originally intended to facilitate using the
+        :meth:`_query.Query.join` method to join across the two relationships
+        at once, however this makes use of a deprecated calling style.
+
+        To use :meth:`_sql.select.join` or :meth:`_orm.Query.join` with
+        an association proxy, the current method is to make use of the
+        :attr:`.AssociationProxyInstance.local_attr` and
+        :attr:`.AssociationProxyInstance.remote_attr` attributes separately::
+
+            stmt = (
+                select(Parent).
+                join(Parent.proxied.local_attr).
+                join(Parent.proxied.remote_attr)
+            )
 
-            sess.query(Parent).join(*Parent.proxied.attr)
+        A future release may seek to provide a more succinct join pattern
+        for association proxy attributes.
 
         .. seealso::