Recorded merge of revisions 51379-51603,51606-52365 via svnmerge from

Recorded merge of revisions 51379-51603,51606-52365 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk/Modules/_ctypes

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  r51379 | thomas.heller | 2006-08-18 16:38:46 +0200 (Fr, 18 Aug 2006) | 6 lines

  Add asserts to check for 'impossible' NULL values, with comments.
  In one place where I'n not 1000% sure about the non-NULL, raise
  a RuntimeError for safety.

  This should fix the klocwork issues that Neal sent me.  If so,
  it should be applied to the release25-maint branch also.
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  r51401 | neal.norwitz | 2006-08-19 06:23:04 +0200 (Sa, 19 Aug 2006) | 4 lines

  Move assert to after NULL check, otherwise we deref NULL in the assert.

  Klocwork #307
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  r51819 | thomas.heller | 2006-09-07 20:56:28 +0200 (Do, 07 Sep 2006) | 5 lines

  Anonymous structure fields that have a bit-width specified did not work,
  and they gave a strange error message from PyArg_ParseTuple:
      function takes exactly 2 arguments (3 given).

  With tests.
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  r51820 | thomas.heller | 2006-09-07 21:09:54 +0200 (Do, 07 Sep 2006) | 4 lines

  The cast function did not accept c_char_p or c_wchar_p instances
  as first argument, and failed with a 'bad argument to internal function'
  error message.
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  r52365 | thomas.heller | 2006-10-17 21:30:48 +0200 (Di, 17 Okt 2006) | 6 lines

  ctypes callback functions only support 'fundamental' result types.
  Check this and raise an error when something else is used - before
  this change ctypes would hang or crash when such a callback was
  called.  This is a partial fix for #1574584.

  Will backport to release25-maint.
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