The fix in #9217 opened up adapt_on_names to more kinds of
expressions than it was prepared for; adjust that logic
and also refine in the ORM where we are using it, as we
dont need it (yet) for the DML RETURNING use case.

Fixed regression introduced in version 2.0.2 due to :ticket:`9217` where
using DML RETURNING statements, as well as
:meth:`_sql.Select.from_statement` constructs as was "fixed" in
:ticket:`9217`, in conjunction with ORM mapped classes that used
expressions such as with :func:`_orm.column_property`, would lead to an
internal error within Core where it would attempt to match the expression
by name. The fix repairs the Core issue, and also adjusts the fix in
:ticket:`9217` to not take effect for the DML RETURNING use case, where it
adds unnecessary overhead.

Fixes: #9273
Change-Id: Ie0344efb12ff7df48f21e71e62dc598c76a6a0de

Fixes: #9183
Change-Id: I1ac3e3698034826122ea8a0cdc9f8f55a10ed6c1

Change-Id: I625af65b3fb1815b1af17dc2ef47dd697fdc3fb1

Improved a fix first made in version 1.4 for :ticket:`8456` which scaled
back the usage of internal "polymorphic adapters", that are used to render
ORM queries when the :paramref:`_orm.Mapper.with_polymorphic` parameter is
used. These adapters, which are very complex and error prone, are now used
only in those cases where an explicit user-supplied subquery is used for
:paramref:`_orm.Mapper.with_polymorphic`, which includes only the use case
of concrete inheritance mappings that use the
:func:`_orm.polymorphic_union` helper, as well as the legacy use case of
using an aliased subquery for joined inheritance mappings, which is not
needed in modern use.

For the most common case of joined inheritance mappings that use the
built-in polymorphic loading scheme, which includes those which make use of
the :paramref:`_orm.Mapper.polymorphic_load` parameter set to ``inline``,
polymorphic adapters are now no longer used. This has both a positive
performance impact on the construction of queries as well as a
substantial simplification of the internal query rendering process.

The specific issue targeted was to allow a :func:`_orm.column_property`
to refer to joined-inheritance classes within a scalar subquery, which now
works as intuitively as is feasible.

ORM context, mapper, strategies now use ORMAdapter in all cases
instead of straight ColumnAdapter; added some more parameters
to ORMAdapter to make this possible.  ORMAdapter now includes a
"trace" enumeration that identifies the use path for the
adapter and can aid in debugging.

implement __slots__ for the ExternalTraversal hierarchy up
to ORMAdapter.  Within this change, we have to change the
ClauseAdapter.wrap() method, which is only used in one polymorphic
codepath, to use copy.copy() instead of
`__dict__` access (apparently `__reduce_ex__` is implemented for
objects with `__slots__`), and we also remove pickling ability,
which should not be needed for adapters (this might have been needed
for 1.3 and earlier in order for Query to be picklable, but none
of that state is present within Query / select() / etc. anymore).

Fixes: #8168
Change-Id: I3f6593eb02ab5e5964807c53a9fa4894c826d017

The issue in #8168 was improved, but not completely fixed,
by #8456.

This includes some small changes to ORM context that
are a prerequisite for getting ORM adaptation to be
better.   Have these in 2.0.0b4 so that we have at
least a better starting point.

References: #8168
Change-Id: I51dbe333b156048836d074fbba1d850f9eb67fd2

command run is "pyupgrade --py37-plus --keep-runtime-typing --keep-percent-format <files...>"
pyupgrade will change assert_ to assertTrue. That was reverted since assertTrue does not
exists in sqlalchemy fixtures

Change-Id: Ie1ed2675c7b11d893d78e028aad0d1576baebb55

The ``aliased()`` constructor calls upon ``__clause_element__()``,
which internally annotates a ``FromClause``, like a subquery.
This became expensive as ``AnnotatedFromClause`` has for
many years called upon ``element.c`` so that the full ``.c``
collection is transferred to the Annotated.

Taking this out proved to be challenging. A straight remove
seemed to not break any tests except for the one that
tested the exact condition.  Nevertheless this seemed
"spooky" so I instead moved the get of ``.c`` to be in a
memoized proxy method.   However, that then exposed
a recursion issue related to loader_criteria; so the
source of that behavior, which was an accidental behavioral
artifact, is now made into an explcicit option that
loader_criteria uses directly.

The accidental behavioral artifact in question is still
kind of strange since I was not able to fully trace out
how it works, but the end result is that fixing the
artifact to be "correct" causes loader_criteria, within
the particular test for #7491, creates a select/
subquery structure with a cycle in it, so compilation fails
with recursion overflow.
The "solution" is to cause the artifact to occur in this
case, which is that the ``AnnotatedFromClause`` will have a
different ``.c`` collection than its element, which is a
subquery.  It's not totally clear how a cycle is generated
when this is not done.

This is commit one of two, which goes through
some hoops to make essentially a one-line change.

The next commit will rework ColumnCollection to optimize
the corresponding_column() method significantly.

Fixes: #8796
Change-Id: Id58ae6554db62139462c11a8be7313a3677456ad

An informative re-raise is now thrown in the case where any "literal
bindparam" render operation fails, indicating the value itself and
the datatype in use, to assist in debugging when literal params
are being rendered in a statement.

Fixes: #8800
Change-Id: Id658f8b03359312353ddbb0c7563026239579f7b

the feature is enabled for all built in backends
when RETURNING is used,
except for Oracle that doesn't need it,  and on
psycopg2 and mssql+pyodbc it is used for all INSERT statements,
not just those that use RETURNING.

third party dialects would need to opt in to the new feature
by setting use_insertmanyvalues to True.

Also adds dialect-level guards against using returning
with executemany where we dont have an implementation to
suit it.   execute single w/ returning still defers to the
server without us checking.

Fixes: #6047
Fixes: #7907
Change-Id: I3936d3c00003f02e322f2e43fb949d0e6e568304