[Python-Dev] Can't compile _tkinter.c with Redhat 9 (post-SF#719880)

[Jeff Hobbs]

> From: martin@v.loewis.de
> I first learned about the problem when a Debian bug report was
> forwarded to Python, along with a patch. I can't recall whether this
> was before or after the 8.4.2 release - notice that the incompatible
> change was in a subminor release.

Well, it was a correction to a bug fix that could cause Tk to crash.
Crashing situations certainly merit placement in patchlevel releases.
I think JeffE was more hoping that ints would remain ints for those
fields with known types, ie use 0 instead of ??.  The problem is that
(IIRC) the type info was ignored for non-valid event data.

> At that time I thought: well, the patch fixes the problem, so let's
> just apply it and, life goes on. The Tk changelog entry reads
> 
> 2003-02-28  Donal K. Fellows  <fellowsd@cs.man.ac.uk>
> 
> 	* tests/bind.test (bind-16.44): 
> 	* generic/tkBind.c (ExpandPercents): Only allow events to see
> 	those expansions that are actually valid for them, and force the
> 	substitution of the rest as "??".  This stops some crashes on
> 	Windows and gets rid of bogus values everywhere.  [Bug #612110]
> 
> which made it quite clear that Tk people would not revert that change,
> no matter what.

When it comes to fixing bugs that can cause compat issues, we are
usually prett good about noting them in direct announcement release
notes.  Checking up, I see that this was noted appropriately in the
Tcl 8.4.2 release announcement (last item):

https://sourceforge.net/project/shownotes.php?release_id=144142

"""
  * Make %-substitutions for events only read data out of the event
    structure when that field is valid for that event type.
	*** POTENTIAL INCOMPATIBILITY ***
"""

  Jeff Hobbs                     The Tcl Guy
  Senior Developer               http://www.ActiveState.com/