[cmake-developers] Regression in language support infrastructure for CMake 2.8.10-rc3

[David Cole]

On Mon, Oct 29, 2012 at 4:36 PM, Alan W. Irwin
<irwin at beluga.phys.uvic.ca> wrote:
> On 2012-10-29 13:16-0400 David Cole wrote:
>
>> The bottom line is: we changed where the output files of an
>> enable_language call go to make them
>> "exact-version-of-CMake-specific". Anybody who was depending on the
>> location of those files needs to update their own code accordingly. I
>> think the number of people/projects affected by this should be quite
>> small... Admittedly: for those that are affected (you, sorry), it's
>> annoying, but it should be easy to apply the above type changes and
>> have your custom language support files work for older and newer
>> versions of CMake.
>>
>> Please let me know if this seems reasonable to you.
>
>
> Hi Dave:
>
> You guys have a very good track record for keeping backwards compatibility,
> but language support is a really special area with relatively few
> groups adding language support externally (although it is clear more
> groups than the PLplot group do this).  Therefore, I completely
> understand why you guys are tempted to go against your track record
> and simply make this backwards incompatible change without adding any
> complications to keep backwards compatibility. Also, from what you
> have said it does seem straightforward (although I haven't tried it
> yet) to modify a particular language's support so it works with the
> new language support infrastructure as well as the old.
>
> How about this for a compromise?  Add a note to your release notes
> that announces this backwards incompatibility introduced into the
> language support infrastructure for 2.8.10.  That note should include
> most of the contents of your e-mail to me about the practical steps
> required for external project's language support to work both with old
> and new language support infrastructure.  Or, better yet, point to a
> text file that is part of the 2.8.10 and future releases that contains
> this essential information.
>
> Also _ideally_ you should check that those update instructions actually work
> for the simple Ada project that you can easily obtain with
>
> svn checkout \
> https://plplot.svn.sourceforge.net/svnroot/plplot/branches/test_cmake/test_ada
>
> I will be applying your instructions to update our D language support
> after lunch.  If those work, I will follow up by doing the same thing
> for Ada (if you don't beat me to it with a patch for how the simple
> Ada project can be updated). Presumably I will be able to give you
> feedback on your instructions by late this afternoon (evening your
> time).  At this point I am not actually completely convinced your
> instructions will work since both D and Ada language support have been
> around a long time and are not nearly as modernized as the core
> language support that appears in CMake-2.8.9.  With luck, that will
> not be an issue for either D or Ada, but we will see.  You
> might want to consider delaying your release until you get feedback
> from me on your instructions, but that decision is up to you.
>
>
> Alan
> __________________________
> Alan W. Irwin
>
> Astronomical research affiliation with Department of Physics and Astronomy,
> University of Victoria (astrowww.phys.uvic.ca).
>
> Programming affiliations with the FreeEOS equation-of-state
> implementation for stellar interiors (freeeos.sf.net); the Time
> Ephemerides project (timeephem.sf.net); PLplot scientific plotting
> software package (plplot.sf.net); the libLASi project
> (unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
> and the Linux Brochure Project (lbproject.sf.net).
> __________________________
>
> Linux-powered Science
> __________________________


The release is delayed already... I'm not going to start building the
final release until after I hear back from you. There are still
several discussions going on around this issue. So.... do let me know
your results.

Thanks,
David