[Python-Dev] 2.6.9 readline [Was: OS X 10.9 Mavericks -> 2.7.6/3.3.3 updates needed]

[Barry Warsaw]

On Oct 24, 2013, at 01:12 PM, Ned Deily wrote:

>Yes, this problem also affects 2.6.  There are some mitigating factors.  The 
>support for libedit on OS X is only enabled when building for an OS X 10.5 or 
>later ABI because in earlier releases, the readline emulation of libedit was 
>judged too buggy.  In 2.6 as is also the case in 2.7, when building from 
>source, ./configure defaults to using a 10.4 ABI unless certain universal 
>build options are selected or the user explicitly sets 
>MACOSX_DEPLOYMENT_TARGET=10.5 or higher when running configure.   With the 
>default 10.4 setting, readline.so fails to build so there is no crash - no 
>readline features, either.  Also, if one supplies a version of GNU readline 
>(which Apple does not ship) as many people do, there is also no crash.
>
>The 2.7 change of Issue18458 (http://hg.python.org/cpython/rev/1e03fd72e116) 
>depends on some previous 2.7-only changes in Modules/readline.c so it does not 
>apply cleanly to 2.6.  However, there aren't *that* many other earlier changes 
>to 2.7 readline that are not in 2.6 and, for the most part, they have to do 
>with fixing memory leaks, including some introduced by using newer versions of 
>GNU readline, and I didn't see any new features.  Copying the current 2.7 tip 
>of readline.c over to the current tip of 2.6 builds cleanly on 10.9.  
>test_readline passes and the simple history scrolling seems to work without 
>crashing.  I'd recommend either doing nothing or backporting everything.

Thanks for the background Ned.

Given that 2.6.9 will be the last release of the 2.6 series, we won't have
much of a chance of going back to fix things if we/I mess it up.

Our options then are to do another release candidate, which frankly will
probably get about as much testing as the first one (i.e. close to zero,
afaict) and push the final release out a few weeks.  Or, as you say we can
just do nothing.  Maybe that means 2.6 will be broken on OS X 10.9 unless
someone crafts and applies patches themselves, but I think that's acceptable
given how old 2.6 is (EOL) and how new 10.9 is.

If 10.9 had come out two weeks from now, "do nothing" would have been the
obvious answer. :) So unless I hear strong objections before next Monday, I am
not going to fix this in 2.6.9.

Cheers,
-Barry