- merge tip

- fixes

diff --cc lib/sqlalchemy/orm/mapper.py
index 1895798b1601fc5e8506e022ff4ecf46c3024f4d,74853dbbaed582bdbe4e2780651d4f8fde2c6bb2..0a89ac78078cd24dbfa862e9759fea9c17fb4578
--- 1/lib/sqlalchemy/orm/mapper.py
--- 2/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@@ -1075,11 -1089,9 +1075,11 @@@ class Mapper(object)
  
      def _is_userland_descriptor(self, obj):
          return not isinstance(obj, 
--                    (MapperProperty, attributes.InstrumentedAttribute)) and \
 -                    hasattr(obj, '__get__')
 -
++                    (MapperProperty, attributes.QueryableAttribute)) and \
 +                    hasattr(obj, '__get__') and not \
 +                     isinstance(obj.__get__(None, obj),
 +                                    attributes.QueryableAttribute)
 +        
      def _should_exclude(self, name, assigned_name, local):
          """determine whether a particular property should be implicitly
          present on the class.

diff --cc lib/sqlalchemy/orm/properties.py
index 09c5042ff39f7b55b317234eaab8e05913197e91,cbfba91f32991006abe24eddcfe84072014ab33d..f50d1e077c967e213a2cc0ab6c9a454dc3447567
--- 1/lib/sqlalchemy/orm/properties.py
--- 2/lib/sqlalchemy/orm/properties.py
+++ b/lib/sqlalchemy/orm/properties.py
@@@ -237,66 -237,9 +237,65 @@@ class CompositeProperty(ColumnProperty)
      def __str__(self):
          return str(self.parent.class_.__name__) + "." + self.key
  
- 
  class DescriptorProperty(MapperProperty):
      """:class:`MapperProperty` which proxies access to a 
 -        plain descriptor."""
 +        user-defined descriptor."""
 +
 +    def instrument_class(self, mapper):
 +        from sqlalchemy.ext import hybrid
 +
 +        # hackety hack hack
 +        class _ProxyImpl(object):
 +            accepts_scalar_loader = False
 +            expire_missing = True
 +
 +            def __init__(self, key):
 +                self.key = key
 +
 +        if self.descriptor is None:
 +            desc = getattr(mapper.class_, self.key, None)
 +            if mapper._is_userland_descriptor(desc):
 +                self.descriptor = desc
 +
 +        if self.descriptor is None:
 +            def fset(obj, value):
 +                setattr(obj, self.name, value)
 +            def fdel(obj):
 +                delattr(obj, self.name)
 +            def fget(obj):
 +                return getattr(obj, self.name)
 +            fget.__doc__ = self.doc
 +
 +            descriptor = hybrid.property_(
 +                fget=fget,
 +                fset=fset,
 +                fdel=fdel,
 +            )
 +        elif isinstance(self.descriptor, property):
 +            descriptor = hybrid.property_(
 +                fget=self.descriptor.fget,
 +                fset=self.descriptor.fset,
 +                fdel=self.descriptor.fdel,
 +            )
 +        else:
 +            descriptor = hybrid.property_(
 +                fget=self.descriptor.__get__,
 +                fset=self.descriptor.__set__,
 +                fdel=self.descriptor.__delete__,
 +            )
 +
 +        proxy_attr = attributes.\
 +                    create_proxied_attribute(self.descriptor or descriptor)\
 +                    (
 +                        self.key, 
 +                        self.descriptor or descriptor,
 +                        lambda: self._comparator_factory(mapper)
 +                    )
 +        def get_comparator(owner):
 +            return proxy_attr
 +        descriptor.expr = get_comparator
 +        descriptor.impl = _ProxyImpl(self.key)
 +        mapper.class_manager.instrument_attribute(self.key, descriptor)
  
      def setup(self, context, entity, path, adapter, **kwargs):
          pass
@@@ -307,7 -250,8 +306,7 @@@
      def merge(self, session, source_state, source_dict, 
                  dest_state, dest_dict, load, _recursive):
          pass
-     
+ 
 -
  class ConcreteInheritedProperty(DescriptorProperty):
      """A 'do nothing' :class:`MapperProperty` that disables 
      an attribute on a concrete subclass that is only present
@@@ -366,17 -314,9 +365,18 @@@ class SynonymProperty(DescriptorPropert
          self.doc = doc or (descriptor and descriptor.__doc__) or None
          util.set_creation_order(self)
  
 +    def _comparator_factory(self, mapper):
 +        prop = getattr(mapper.class_, self.name).property
 +
 +        if self.comparator_factory:
 +            comp = self.comparator_factory(prop, mapper)
 +        else:
 +            comp = prop.comparator_factory(prop, mapper)
 +        return comp
 +
      def set_parent(self, parent, init):
          if self.map_column:
+             # implement the 'map_column' option.
              if self.key not in parent.mapped_table.c:
                  raise sa_exc.ArgumentError(
                      "Can't compile synonym '%s': no column on table "

diff --cc lib/sqlalchemy/orm/util.py
index 49f572572c04e23a435ca71f6f401d59096d1136,0f4adec001ea6b1fa1ae7a6979f266cc2f08ca65..be2b024a2c6d091824ed0d78ee21fb887c2c5b56
--- 1/lib/sqlalchemy/orm/util.py
--- 2/lib/sqlalchemy/orm/util.py
+++ b/lib/sqlalchemy/orm/util.py
@@@ -546,7 -548,7 +546,7 @@@ def _entity_descriptor(entity, key)
      """
      if not isinstance(entity, (AliasedClass, type)):
          entity = entity.class_
-         
 -    
++
      try:
          return getattr(entity, key)
      except AttributeError:

diff --cc test/orm/test_query.py
Simple merge