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 pep484 task becomes more intense as there is mounting
pressure to come up with a consistency in how data moves
from end-user to instance variable.

current thinking is coming into:

1. there are _typing._XYZArgument objects that represent "what the
   user sent"
2. there's the roles, which represent a kind of "filter" for different
   kinds of objects.   These are mostly important as the argument
   we pass to coerce().
3. there's the thing that coerce() returns, which should be what the
   construct uses as its internal representation of the thing.
   This is _typing._XYZElement.

but there's some controversy over whether or
not we should pass actual ClauseElements around by their role
or not.   I think we shouldn't at the moment, but this makes the
"role-ness" of something a little less portable. Like, we have
to set DMLTableRole for TableClause, Join, and Alias, but then
also we have to repeat those three types in order to set up
_DMLTableElement.

Other change introduced here, there was a deannotate=True
for the left/right of a sql.join().    All tests pass without that.
I'd rather not have that there as if we have a join(A, B) where
A, B are mapped classes, we want them inside of the _annotations.
The rationale seems to be performance, but this performance can
be illustrated to be on the compile side which we hope is cached
in the normal case.

CTEs now accommodate for text selects including recursive.

Get typing to accommodate "util.preloaded" cleanly; add "preloaded"
as a real module.  This seemed like we would have needed
pep562 `__getattr__()` but we don't, just set names in
globals() as we import them.

References: #6810
Change-Id: I34d17f617de2fe2c086fc556bd55748dc782faf0

References: #4600
Change-Id: I2a62ddfe00bc562720f0eae700a497495d7a987a

Fixed issue in SQL compiler where the bound parameters set up for a
:class:`.Values` construct wouldn't be positionally tracked correctly if
inside of a :class:`_sql.CTE`, affecting database drivers that support
VALUES + ctes and use positional parameters such as SQL Server in
particular as well as asyncpg.   The fix also repairs support for
compiler flags such as ``literal_binds``.

Fixes: #6327
Change-Id: I2d549228691d0bfc10dadd0955b1549d7584db51

Fixed issue in new :class:`_sql.Values` construct where passing tuples of
objects would fall back to per-value type detection rather than making use
of the :class:`_schema.Column` objects passed directly to
:class:`_sql.Values` that tells SQLAlchemy what the expected type is. This
would lead to issues for objects such as enumerations and numpy strings
that are not actually necessary since the expected type is given.

note this changes NullType() to raise CompileError for
literal_processor; NullType() does not imply the actual value
NULL as much as it does "unknown type" so this should make failure
modes more clear.

Fixes: #5785
Change-Id: Ifbf5e78373102380b301098f30e15011efa98b5e

It's better, the majority of these changes look more readable to me.
also found some docstrings that had formatting / quoting issues.

Change-Id: I582a45fde3a5648b2f36bab96bad56881321899b

This change includes mainly that the bracketed use within
select() is moved to positional, and keyword arguments are
removed from calls to the select() function.  it does not
yet fully address other issues such as keyword arguments passed
to the table.select().

Additionally, allows False / None to both be considered
as "disable" for all of select.correlate(), select.correlate_except(),
query.correlate(), which establishes consistency with
passing of ``False`` for the legact select(correlate=False)
argument.

Change-Id: Ie6c6e6abfbd3d75d4c8de504c0cf0159e6999108

Added a core :class:`Values` object that enables a VALUES construct
to be used in the FROM clause of an SQL statement for databases that
support it (mainly PostgreSQL and SQL Server).

Fixes: #4868
Closes: #5030
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5030
Pull-request-sha: 84684038a8efa93b460318e0db53f6c644554588

Change-Id: Ib8109b63bc1a9dc04ab987c5322ca3375f7e824d