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

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

  Fix some py3k warnings in the standard library.
........

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

........
  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.
........
  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.
........
  r77510 | brett.cannon | 2010-01-14 19:31:45 -0600 (Thu, 14 Jan 2010) | 1 line

  Remove C++/C99-style comments.
........

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.

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.

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.

svn+ssh://svn.python.org/python/branches/py3k

................
  r75797 | georg.brandl | 2009-10-27 16:28:25 +0100 (Di, 27 Okt 2009) | 129 lines

  Merged revisions 75365,75394,75402-75403,75418,75459,75484,75592-75596,75600,75602-75607,75610-75613,75616-75617,75623,75627,75640,75647,75696,75795 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/trunk

  ........
    r75365 | georg.brandl | 2009-10-11 22:16:16 +0200 (So, 11 Okt 2009) | 1 line

    Fix broken links found by "make linkcheck".  scipy.org seems to be done right now, so I could not verify links going there.
  ........
    r75394 | georg.brandl | 2009-10-13 20:10:59 +0200 (Di, 13 Okt 2009) | 1 line

    Fix markup.
  ........
    r75402 | georg.brandl | 2009-10-14 17:51:48 +0200 (Mi, 14 Okt 2009) | 1 line

    #7125: fix typo.
  ........
    r75403 | georg.brandl | 2009-10-14 17:57:46 +0200 (Mi, 14 Okt 2009) | 1 line

    #7126: os.environ changes *do* take effect in subprocesses started with os.system().
  ........
    r75418 | georg.brandl | 2009-10-14 20:48:32 +0200 (Mi, 14 Okt 2009) | 1 line

    #7116: str.join() takes an iterable.
  ........
    r75459 | georg.brandl | 2009-10-17 10:57:43 +0200 (Sa, 17 Okt 2009) | 1 line

    Fix refleaks in _ctypes PyCSimpleType_New, which fixes the refleak seen in test___all__.
  ........
    r75484 | georg.brandl | 2009-10-18 09:58:12 +0200 (So, 18 Okt 2009) | 1 line

    Fix missing word.
  ........
    r75592 | georg.brandl | 2009-10-22 09:05:48 +0200 (Do, 22 Okt 2009) | 1 line

    Fix punctuation.
  ........
    r75593 | georg.brandl | 2009-10-22 09:06:49 +0200 (Do, 22 Okt 2009) | 1 line

    Revert unintended change.
  ........
    r75594 | georg.brandl | 2009-10-22 09:56:02 +0200 (Do, 22 Okt 2009) | 1 line

    Fix markup.
  ........
    r75595 | georg.brandl | 2009-10-22 09:56:56 +0200 (Do, 22 Okt 2009) | 1 line

    Fix duplicate target.
  ........
    r75596 | georg.brandl | 2009-10-22 10:05:04 +0200 (Do, 22 Okt 2009) | 1 line

    Add a new directive marking up implementation details and start using it.
  ........
    r75600 | georg.brandl | 2009-10-22 13:01:46 +0200 (Do, 22 Okt 2009) | 1 line

    Make it more robust.
  ........
    r75602 | georg.brandl | 2009-10-22 13:28:06 +0200 (Do, 22 Okt 2009) | 1 line

    Document new directive.
  ........
    r75603 | georg.brandl | 2009-10-22 13:28:23 +0200 (Do, 22 Okt 2009) | 1 line

    Allow short form with text as argument.
  ........
    r75604 | georg.brandl | 2009-10-22 13:36:50 +0200 (Do, 22 Okt 2009) | 1 line

    Fix stylesheet for multi-paragraph impl-details.
  ........
    r75605 | georg.brandl | 2009-10-22 13:48:10 +0200 (Do, 22 Okt 2009) | 1 line

    Use "impl-detail" directive where applicable.
  ........
    r75606 | georg.brandl | 2009-10-22 17:00:06 +0200 (Do, 22 Okt 2009) | 1 line

    #6324: membership test tries iteration via __iter__.
  ........
    r75607 | georg.brandl | 2009-10-22 17:04:09 +0200 (Do, 22 Okt 2009) | 1 line

    #7088: document new functions in signal as Unix-only.
  ........
    r75610 | georg.brandl | 2009-10-22 17:27:24 +0200 (Do, 22 Okt 2009) | 1 line

    Reorder __slots__ fine print and add a clarification.
  ........
    r75611 | georg.brandl | 2009-10-22 17:42:32 +0200 (Do, 22 Okt 2009) | 1 line

    #7035: improve docs of the various <method>_errors() functions, and give them docstrings.
  ........
    r75612 | georg.brandl | 2009-10-22 17:52:15 +0200 (Do, 22 Okt 2009) | 1 line

    #7156: document curses as Unix-only.
  ........
    r75613 | georg.brandl | 2009-10-22 17:54:35 +0200 (Do, 22 Okt 2009) | 1 line

    #6977: getopt does not support optional option arguments.
  ........
    r75616 | georg.brandl | 2009-10-22 18:17:05 +0200 (Do, 22 Okt 2009) | 1 line

    Add proper references.
  ........
    r75617 | georg.brandl | 2009-10-22 18:20:55 +0200 (Do, 22 Okt 2009) | 1 line

    Make printout margin important.
  ........
    r75623 | georg.brandl | 2009-10-23 10:14:44 +0200 (Fr, 23 Okt 2009) | 1 line

    #7188: fix optionxform() docs.
  ........
    r75627 | fred.drake | 2009-10-23 15:04:51 +0200 (Fr, 23 Okt 2009) | 2 lines

    add further note about what's passed to optionxform
  ........
    r75640 | neil.schemenauer | 2009-10-23 21:58:17 +0200 (Fr, 23 Okt 2009) | 2 lines

    Improve some docstrings in the 'warnings' module.
  ........
    r75647 | georg.brandl | 2009-10-24 12:04:19 +0200 (Sa, 24 Okt 2009) | 1 line

    Fix markup.
  ........
    r75696 | georg.brandl | 2009-10-25 21:25:43 +0100 (So, 25 Okt 2009) | 1 line

    Fix a demo.
  ........
    r75795 | georg.brandl | 2009-10-27 16:10:22 +0100 (Di, 27 Okt 2009) | 1 line

    Fix a strange mis-edit.
  ........
................

Merged revisions 75365,75394,75402-75403,75418,75459,75484,75592-75596,75600,75602-75607,75610-75613,75616-75617,75623,75627,75640,75647,75696,75795 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

........
  r75365 | georg.brandl | 2009-10-11 22:16:16 +0200 (So, 11 Okt 2009) | 1 line

  Fix broken links found by "make linkcheck".  scipy.org seems to be done right now, so I could not verify links going there.
........
  r75394 | georg.brandl | 2009-10-13 20:10:59 +0200 (Di, 13 Okt 2009) | 1 line

  Fix markup.
........
  r75402 | georg.brandl | 2009-10-14 17:51:48 +0200 (Mi, 14 Okt 2009) | 1 line

  #7125: fix typo.
........
  r75403 | georg.brandl | 2009-10-14 17:57:46 +0200 (Mi, 14 Okt 2009) | 1 line

  #7126: os.environ changes *do* take effect in subprocesses started with os.system().
........
  r75418 | georg.brandl | 2009-10-14 20:48:32 +0200 (Mi, 14 Okt 2009) | 1 line

  #7116: str.join() takes an iterable.
........
  r75459 | georg.brandl | 2009-10-17 10:57:43 +0200 (Sa, 17 Okt 2009) | 1 line

  Fix refleaks in _ctypes PyCSimpleType_New, which fixes the refleak seen in test___all__.
........
  r75484 | georg.brandl | 2009-10-18 09:58:12 +0200 (So, 18 Okt 2009) | 1 line

  Fix missing word.
........
  r75592 | georg.brandl | 2009-10-22 09:05:48 +0200 (Do, 22 Okt 2009) | 1 line

  Fix punctuation.
........
  r75593 | georg.brandl | 2009-10-22 09:06:49 +0200 (Do, 22 Okt 2009) | 1 line

  Revert unintended change.
........
  r75594 | georg.brandl | 2009-10-22 09:56:02 +0200 (Do, 22 Okt 2009) | 1 line

  Fix markup.
........
  r75595 | georg.brandl | 2009-10-22 09:56:56 +0200 (Do, 22 Okt 2009) | 1 line

  Fix duplicate target.
........
  r75596 | georg.brandl | 2009-10-22 10:05:04 +0200 (Do, 22 Okt 2009) | 1 line

  Add a new directive marking up implementation details and start using it.
........
  r75600 | georg.brandl | 2009-10-22 13:01:46 +0200 (Do, 22 Okt 2009) | 1 line

  Make it more robust.
........
  r75602 | georg.brandl | 2009-10-22 13:28:06 +0200 (Do, 22 Okt 2009) | 1 line

  Document new directive.
........
  r75603 | georg.brandl | 2009-10-22 13:28:23 +0200 (Do, 22 Okt 2009) | 1 line

  Allow short form with text as argument.
........
  r75604 | georg.brandl | 2009-10-22 13:36:50 +0200 (Do, 22 Okt 2009) | 1 line

  Fix stylesheet for multi-paragraph impl-details.
........
  r75605 | georg.brandl | 2009-10-22 13:48:10 +0200 (Do, 22 Okt 2009) | 1 line

  Use "impl-detail" directive where applicable.
........
  r75606 | georg.brandl | 2009-10-22 17:00:06 +0200 (Do, 22 Okt 2009) | 1 line

  #6324: membership test tries iteration via __iter__.
........
  r75607 | georg.brandl | 2009-10-22 17:04:09 +0200 (Do, 22 Okt 2009) | 1 line

  #7088: document new functions in signal as Unix-only.
........
  r75610 | georg.brandl | 2009-10-22 17:27:24 +0200 (Do, 22 Okt 2009) | 1 line

  Reorder __slots__ fine print and add a clarification.
........
  r75611 | georg.brandl | 2009-10-22 17:42:32 +0200 (Do, 22 Okt 2009) | 1 line

  #7035: improve docs of the various <method>_errors() functions, and give them docstrings.
........
  r75612 | georg.brandl | 2009-10-22 17:52:15 +0200 (Do, 22 Okt 2009) | 1 line

  #7156: document curses as Unix-only.
........
  r75613 | georg.brandl | 2009-10-22 17:54:35 +0200 (Do, 22 Okt 2009) | 1 line

  #6977: getopt does not support optional option arguments.
........
  r75616 | georg.brandl | 2009-10-22 18:17:05 +0200 (Do, 22 Okt 2009) | 1 line

  Add proper references.
........
  r75617 | georg.brandl | 2009-10-22 18:20:55 +0200 (Do, 22 Okt 2009) | 1 line

  Make printout margin important.
........
  r75623 | georg.brandl | 2009-10-23 10:14:44 +0200 (Fr, 23 Okt 2009) | 1 line

  #7188: fix optionxform() docs.
........
  r75627 | fred.drake | 2009-10-23 15:04:51 +0200 (Fr, 23 Okt 2009) | 2 lines

  add further note about what's passed to optionxform
........
  r75640 | neil.schemenauer | 2009-10-23 21:58:17 +0200 (Fr, 23 Okt 2009) | 2 lines

  Improve some docstrings in the 'warnings' module.
........
  r75647 | georg.brandl | 2009-10-24 12:04:19 +0200 (Sa, 24 Okt 2009) | 1 line

  Fix markup.
........
  r75696 | georg.brandl | 2009-10-25 21:25:43 +0100 (So, 25 Okt 2009) | 1 line

  Fix a demo.
........
  r75795 | georg.brandl | 2009-10-27 16:10:22 +0100 (Di, 27 Okt 2009) | 1 line

  Fix a strange mis-edit.
........

svn+ssh://svn.python.org/python/branches/py3k

................
  r74821 | georg.brandl | 2009-09-16 11:42:19 +0200 (Mi, 16 Sep 2009) | 1 line

  #6885: run python 3 as python3.
................
  r74828 | georg.brandl | 2009-09-16 16:23:20 +0200 (Mi, 16 Sep 2009) | 1 line

  Use true booleans.
................
  r74829 | georg.brandl | 2009-09-16 16:24:29 +0200 (Mi, 16 Sep 2009) | 1 line

  Small PEP8 correction.
................
  r74830 | georg.brandl | 2009-09-16 16:36:22 +0200 (Mi, 16 Sep 2009) | 1 line

  Use true booleans.
................
  r74831 | georg.brandl | 2009-09-16 17:54:04 +0200 (Mi, 16 Sep 2009) | 1 line

  Use true booleans and PEP8 for argdefaults.
................
  r74833 | georg.brandl | 2009-09-16 17:58:14 +0200 (Mi, 16 Sep 2009) | 1 line

  Last round of adapting style of documenting argument default values.
................
  r74835 | georg.brandl | 2009-09-16 18:00:31 +0200 (Mi, 16 Sep 2009) | 33 lines

  Merged revisions 74817-74820,74822-74824 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/trunk

  ........
    r74817 | georg.brandl | 2009-09-16 11:05:11 +0200 (Mi, 16 Sep 2009) | 1 line

    Make deprecation notices as visible as warnings are right now.
  ........
    r74818 | georg.brandl | 2009-09-16 11:23:04 +0200 (Mi, 16 Sep 2009) | 1 line

    #6880: add reference to classes section in exceptions section, which comes earlier.
  ........
    r74819 | georg.brandl | 2009-09-16 11:24:57 +0200 (Mi, 16 Sep 2009) | 1 line

    #6876: fix base class constructor invocation in example.
  ........
    r74820 | georg.brandl | 2009-09-16 11:30:48 +0200 (Mi, 16 Sep 2009) | 1 line

    #6891: comment out dead link to Unicode article.
  ........
    r74822 | georg.brandl | 2009-09-16 12:12:06 +0200 (Mi, 16 Sep 2009) | 1 line

    #5621: refactor description of how class/instance attributes interact on a.x=a.x+1 or augassign.
  ........
    r74823 | georg.brandl | 2009-09-16 15:06:22 +0200 (Mi, 16 Sep 2009) | 1 line

    Remove strange trailing commas.
  ........
    r74824 | georg.brandl | 2009-09-16 15:11:06 +0200 (Mi, 16 Sep 2009) | 1 line

    #6892: fix optparse example involving help option.
  ........
................

Was a DeprecationWarning for not supporting it since Python 2.6.

Closes issue #3652.

Issue #3781: Final cleanup of warnings.catch_warnings and its usage in the test suite. Closes issue w.r.t. 2.6 (R: Brett Cannon)

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

........
  r66321 | brett.cannon | 2008-09-08 17:49:16 -0700 (Mon, 08 Sep 2008) | 7 lines

  warnings.catch_warnings() now returns a list or None instead of the custom
  WarningsRecorder object. This makes the API simpler to use as no special object
  must be learned.

  Closes issue 3781.
  Review by Benjamin Peterson.
........

WarningsRecorder object. This makes the API simpler to use as no special object
must be learned.

Closes issue 3781.
Review by Benjamin Peterson.

Closes issue 3776.
Review by Nick Coghlan.

with moving warnings.catch_warnings() over to keyword-only parameters for its
constructor (as documented in the 2.6 docs).

catch_warnings(), and clean up the API.

While expanding the test suite, a bug was found where a warning about the
'line' argument to showwarning() was not letting functions with '*args' go
without a warning.

Closes issue 3602.
Code review by Benjamin Peterson.