Fixed issue where using additional relationship criteria with the
:func:`_orm.joinedload` loader option, where the additional criteria itself
contained correlated subqueries that referred to the joined entities and
therefore also required "adaption" to aliased entities, would be excluded
from this adaption, producing the wrong ON clause for the joinedload.

Fixes: #9779
Change-Id: Idcfec3e760057fbf6a09c10ad67a0bb4bf70f03a

fix a handful of warnings that were emitting but not raising,
usually because they were inside an "expect_warnings" block.

modify "expect_warnings" to always use "raise_on_any_unexpected"
behavior; remove this parameter.

Fixed issue in semi-private ``await_only()`` and ``await_fallback()``
concurrency functions where the given awaitable would remain un-awaited if
the function threw a ``GreenletError``, which could cause "was not awaited"
warnings later on if the program continued. In this case, the given
awaitable is now cancelled before the exception is thrown.

Change-Id: I33668c5e8c670454a3d879e559096fb873b57244

Fixed loader strategy pathing issues where eager loaders such as
:func:`_orm.joinedload` / :func:`_orm.selectinload` would fail to traverse
fully for many-levels deep following a load that had a
:func:`_orm.with_polymorphic` or similar construct as an interim member.

Here we can take advantage of 2.0's refactoring of strategy_options
to identify the "chop_path" concept can be simplified to work
with "natural" paths alone.

In addition, identified existing
logic in PropRegistry that works fine, but needed the "is_unnatural"
attribute to be more accurate for a given path, so we set that
up front to True if the ancestor is_unnatural.

Fixes: #9715
Change-Id: Ie6b3f55b6a23d0d32628afd22437094263745114

Expanded the warning emitted when a plain :func:`_sql.column` object is
present in a Declarative mapping to include any arbitrary SQL expression
that is not declared within an appropriate property type such as
:func:`_orm.column_property`, :func:`_orm.deferred`, etc. These attributes
are otherwise not mapped at all and remain unchanged within the class
dictionary. As it seems likely that such an expression is usually not
what's intended, this case now warns for all such otherwise ignored
expressions, rather than just the :func:`_sql.column` case.

Fixes: #9537
Change-Id: Ic4ca7a071a28adf4ea8680690025d927522a0805

SQL Server has been failing on this test for a month as it does
not allow a PK on VARCHAR(max)

Change-Id: I3f43e660275e03ced1b584fe9d3c7f34f5558330

Added support for the :paramref:`_orm.Mapper.polymorphic_load` parameter to
be applied to each mapper in an inheritance hierarchy more than one level
deep, allowing columns to load for all classes in the hierarchy that
indicate ``"selectin"`` using a single statement, rather than ignoring
elements on those intermediary classes that nonetheless indicate they also
would participate in ``"selectin"`` loading and were not part of the
base-most SELECT statement.

Fixes: #9373
Change-Id: If8dcba0f0191f6c2818ecd15870bccfdf5ce1112

first change:

Reworked the :ref:`examples_versioned_history` to work with
version 2.0, while at the same time improving the overall working of
this example to use newer APIs, including a newly added hook
:meth:`_orm.MapperEvents.after_mapper_constructed`.

second change:

Added new event hook :meth:`_orm.MapperEvents.after_mapper_constructed`,
which supplies an event hook to take place right as the
:class:`_orm.Mapper` object has been fully constructed, but before the
:meth:`_orm.registry.configure` call has been called. This allows code that
can create additional mappings and table structures based on the initial
configuration of a :class:`_orm.Mapper`, which also integrates within
Declarative configuration. Previously, when using Declarative, where the
:class:`_orm.Mapper` object is created within the class creation process,
there was no documented means of running code at this point.  The change
is to immediately benefit custom mapping schemes such as that
of the :ref:`examples_versioned_history` example, which generate additional
mappers and tables in response to the creation of mapped classes.

third change:

The infrequently used :attr:`_orm.Mapper.iterate_properties` attribute and
:meth:`_orm.Mapper.get_property` method, which are primarily used
internally, no longer implicitly invoke the :meth:`_orm.registry.configure`
process. Public access to these methods is extremely rare and the only
benefit to having :meth:`_orm.registry.configure` would have been allowing
"backref" properties be present in these collections. In order to support
the new :meth:`_orm.MapperEvents.after_mapper_constructed` event, iteration
and access to the internal :class:`_orm.MapperProperty` objects is now
possible without triggering an implicit configure of the mapper itself.

The more-public facing route to iteration of all mapper attributes, the
:attr:`_orm.Mapper.attrs` collection and similar, will still implicitly
invoke the :meth:`_orm.registry.configure` step thus making backref
attributes available.

In all cases, the :meth:`_orm.registry.configure` is always available to
be called directly.

fourth change:

Fixed obscure ORM inheritance issue caused by :ticket:`8705` where some
scenarios of inheriting mappers that indicated groups of columns from the
local table and the inheriting table together under a
:func:`_orm.column_property` would nonetheless warn that properties of the
same name were being combined implicitly.

Fixes: #9220
Fixes: #9232
Change-Id: Id335b8e8071c8ea509c057c389df9dcd2059437d

Fixed regression where using the :paramref:`_orm.Mapper.version_id_col`
feature with a regular Python-side incrementing column would fail to work
for SQLite and other databases that don't support "rowcount" with
"RETURNING", as "RETURNING" would be assumed for such columns even though
that's not what actually takes place.

Fixes: #9228
Change-Id: I6a1a7fa4d63e183fe4ef0fbfd3cb5cac03b26d78

Improved the error reporting when linking strategy options from a base
class to another attribute that's off a subclass, where ``of_type()``
should be used. Previously, when :meth:`.Load.options` is used, the message
would lack informative detail that ``of_type()`` should be used, which was
not the case when linking the options directly. The informative detail now
emits even if :meth:`.Load.options` is used.

Fixes: #9182
Change-Id: Ibc14923d0cbca9114316cb7db2b30f091dc28af8