Ensure custom formatwarning function can receive line as positional argument.
Co-Authored-By: Tashrif Billah <tashrifbillah@gmail.com>

The warnings module now suggests to enable tracemalloc if the source
is specified, tracemalloc module is available, but tracemalloc is not
tracing memory allocations.

More consistent with how other parts of Python find the filename (e.g. tracebacks and pdb).

* Add coro.cr_origin and sys.set_coroutine_origin_tracking_depth
* Use coroutine origin information in the unawaited coroutine warning
* Stop using set_coroutine_wrapper in asyncio debug mode
* In BaseEventLoop.set_debug, enable debugging in the correct thread

- primary change is to add a new default filter entry for
  'default::DeprecationWarning:__main__'
- secondary change is an internal one to cope with plain
  strings in the warning module's internal filter list
  (this avoids the need to create a compiled regex object
  early on during interpreter startup)
- assorted documentation updates, including many more
  examples of configuring the warnings settings
- additional tests to ensure that both the pure Python and
  the C accelerated warnings modules have the expected
  default configuration

Rather than supporting dev mode directly in the warnings module, this
instead adjusts the initialisation code to add an extra 'default'
entry to sys.warnoptions when dev mode is enabled.

This ensures that dev mode behaves *exactly* as if `-Wdefault` had
been passed on the command line, including in the way it interacts
with `sys.warnoptions`, and with other command line flags like `-bb`.

Fix also bpo-20361: have -b & -bb options take precedence over any
other warnings options.

Patch written by Nick Coghlan, with minor modifications of Victor Stinner.

* Add most_recent_first parameter to tracemalloc.Traceback.format to allow
   reversing the order of the frames in the output
* Reversed default sorting of tracemalloc.Traceback frames
* Allowed negative limit, truncating from the other side.

The warnings module doesn't leak memory anymore in the hidden
warnings registry for the "ignore" action of warnings filters.

The warn_explicit() function doesn't add the warning key to the
registry anymore for the "ignore" action.

In development and debug mode, use the "default" action, rather than
the "always" action, for ResourceWarning in the default warnings
filters.

* Optimize warnings.filterwarnings(). Replace re.compile('') with
  None to avoid the cost of calling a regex.match() method, whereas
  it always matchs.
* Optimize get_warnings_attr(): replace PyObject_GetAttrString() with
  _PyObject_GetAttrId().

Cleanup also create_filter():

* Use _Py_IDENTIFIER() to allow to cleanup strings at Python
  finalization
* Replace Py_FatalError() with a regular exceptions

The developer mode (-X dev) now creates all default warnings filters
to order filters in the correct order to always show ResourceWarning
and make BytesWarning depend on the -b option.

Write a functional test to make sure that ResourceWarning is logged
twice at the same location in the developer mode.

Add a new 'dev_mode' field to _PyCoreConfig.

When Python is build is debug mode (Py_DEBUG), DeprecationWarning,
PendingDeprecationWarning and ImportWarning warnings are now
displayed by default.

test_venv: run "-m pip" and "-m ensurepip._uninstall" with -W
ignore::DeprecationWarning since pip code is not part of Python.

Metaprogramming a list of attributes was excessive, and made the code less readable and slower.

This hides unwanted implementation details from tracebacks.

Patch by Serhiy Storchaka.

Issue #28089: Fix a regression introduced in warnings.catch_warnings(): call
warnings.showwarning() if it was overriden inside the context manager.

Based on patch by Alex Shkop.

Issue #21925: warnings.formatwarning() now catches exceptions on
linecache.getline(...) to be able to log ResourceWarning emitted late during
the Python shutdown process.

Issue #26604:

* Add a new optional source parameter to _warnings.warn() and warnings.warn()
* Modify asyncore, asyncio and _pyio modules to set the source parameter when
  logging a ResourceWarning warning

Issue #26568: Fix implementation of showwarning() and formatwarning() for
test_logging.

Issue #26567:

* Add a new function PyErr_ResourceWarning() function to pass the destroyed
  object
* Add a source attribute to warnings.WarningMessage
* Add warnings._showwarnmsg() which uses tracemalloc to get the traceback where
  source object was allocated.

Issue #26568: add new  _showwarnmsg() and _formatwarnmsg() functions to the
warnings module.

The C function warn_explicit() now calls warnings._showwarnmsg() with a
warnings.WarningMessage as parameter, instead of calling warnings.showwarning()
with multiple parameters.

_showwarnmsg() calls warnings.showwarning() if warnings.showwarning() was
replaced. Same for _formatwarnmsg(): call warnings.formatwarning() if it was
replaced.

by the warnings.warn(stacklevel=) parameter.

The concept of .pyo files no longer exists. Now .pyc files have an
optional `opt-` tag which specifies if any extra optimizations beyond
the peepholer were applied.

is run with pythonw.exe.

Thanks to Jon Poler for the patch.

Initial patch by Phil Elson.

Close #19379: Lazily import linecache in the warnings module, to make startup with warnings faster until a warning gets printed.

ModuleNotFoundError.

except when configured --with-pydebug.

Emit this warning from the GC shutdown procedure, rather than just printing to stderr.

'once_registry'. This is bad as the warnings module had variables named
'defaultaction' and 'onceregistry' which are what people should be looking at
(technically those variables shouldn't be mucked with as they are undocumented,
but we all know better than to believe that isn't happening). So the variables
from _warnings have been renamed to come off as private and to avoid confusion
over what variable should be used.

Closes issue #9766. Thanks to Antoine Pitrou for the discovery.

svn+ssh://pythondev@svn.python.org/python/trunk

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  r78757 | florent.xicluna | 2010-03-07 14:14:25 +0200 (Sun, 07 Mar 2010) | 2 lines

  Fix some py3k warnings in the standard library.
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svn+ssh://pythondev@svn.python.org/python/trunk

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  r77402 | brett.cannon | 2010-01-09 20:56:19 -0600 (Sat, 09 Jan 2010) | 12 lines

  DeprecationWarning is now silent by default.

  This was originally suggested by Guido, discussed on the stdlib-sig mailing
  list, and given the OK by Guido directly to me. What this change essentially
  means is that Python has taken a policy of silencing warnings that are only
  of interest to developers by default. This should prevent users from seeing
  warnings which are triggered by an application being run against a new
  interpreter before the app developer has a chance to update their code.

  Closes issue #7319. Thanks to Antoine Pitrou, Ezio Melotti, and Brian Curtin
  for helping with the issue.
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  r77505 | brett.cannon | 2010-01-14 14:00:28 -0600 (Thu, 14 Jan 2010) | 7 lines

  The silencing of DeprecationWarning was not taking -3 into consideration. Since
  Py3K warnings are DeprecationWarning by default this was causing -3 to
  essentially be a no-op. Now DeprecationWarning is only silenced if -3 is not
  used.

  Closes issue #7700. Thanks Ezio Melotti and Florent Xicluna for patch help.
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  r77510 | brett.cannon | 2010-01-14 19:31:45 -0600 (Thu, 14 Jan 2010) | 1 line

  Remove C++/C99-style comments.
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by default as well. This change fixes that by treating -Q like -3 when it comes
to DeprecationWarning; using it causes the silencing to not occur.

Fixes issue #7319.