to transient objects with attributes unset would leak NEVER_SET,
and negated_contains_or_equals would do so for any transient
object as the comparison used only the committed value.
Repaired the NEVER_SET cases, fixes #3371, and also made
negated_contains_or_equals() use state_attr_by_column() just
like a non-negated comparison, fixes #3374

and :class:`.CheckConstraint` has been further enhanced such that
when the constraint is associated with non-table-bound :class:`.Column`
objects, the constraint will set up event listeners with the
columns themselves such that the constraint auto attaches at the
same time the columns are associated with the table.  This in particular
helps in some edge cases in declarative but is also of general use.
fixes #3341

objects, such that they were prevented from being called outside
of the declarative process; this is related to the enhancements
of #3150 which allow ``@declared_attr`` to return a value that is
cached based on the current class as it's being configured.
The exception raise has been removed, and the behavior changed
so that outside of the declarative process, the function decorated by
``@declared_attr`` is called every time just like a regular
``@property``, without using any caching, as none is available
at this stage.
fixes #3331

simple but unusual system allows for a dramatic savings in Python
overhead for the construction and processing of orm :class:`.Query`
objects, from query construction up through rendering of a string
SQL statement.
fixes #3054

of a declarative inheritance hierarchy would prevent attributes
and configuration being correctly propagated from the base class
to the inheriting class.
fixes #3219 fixes #3240

subclass, the value returned by the descriptor is not available
because the superclass is already mapped with the InstrumentedAttribute,
until the subclass is mapped.  We add a setattr() to set up that
attribute so that the __mapper_args__ hook and possibly others
have access to the "cascaded" version of the attribute within
the call.

on engines

when using :class:`.AbstractConcreteBase` in conjunction with
a subclass that declares ``__abstract__``.
fixes #3185