[cmake-developers] Use OBJECT_DEPENDS in qt4_generate_moc() ?

[Alexander Neundorf]

On Friday 27 July 2012, David Cole wrote:
> On Fri, Jul 27, 2012 at 4:27 PM, Alexander Neundorf <neundorf at kde.org> 
wrote:
> > On Thursday 05 July 2012, David Cole wrote:
> >> On Thu, Jul 5, 2012 at 12:29 PM, Clinton Stimpson <clinton at elemtech.com>
> >> 
> >> wrote:
> >> > On Thursday, July 05, 2012 06:20:56 PM Alexander Neundorf wrote:
> >> >> On Thursday, 5. July 2012 17:37:21 Clinton Stimpson wrote:
> >> >> > On Friday, June 15, 2012 09:56:51 PM Alexander Neundorf wrote:
> >> >> > > Hi,
> >> >> > > 
> >> >> > > 
> >> >> > > 
> >> >> > > attached is a small patch which sets the OBJECT_DEPENDS property
> >> >> > > of
> >> >> > > 
> >> >> > > a
> >> >> > > 
> >> >> > > moced file to the generated moc file.
> >> >> > > 
> >> >> > > This has the effect that before the cpp file is built, moc has
> >> >> > > been
> >> >> > > 
> >> >> > > run
> >> >> > > 
> >> >> > > on it. We have that in KDE's version of qt4_generate_moc() this
> >> >> > > way
> >> >> > > 
> >> >> > > since 2006 and it works for us.
> >> >> > > 
> >> >> > > In cmake's version, it was removed January 11th 2008, the removed
> >> >> > > 
> >> >> > > call to MACRO_ADD_FILE_DEPENDENCIES():
> >> >> > > 
> >> >> > > 
> >> >> > > http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=510f578f8b5385
> >> >> > > 8fb
> >> >> > > 
> >> >> > > b541c 4e7 e4731de9bfbd483
> >> >> > > 
> >> >> > > 
> >> >> > > 
> >> >> > > Now since we are trying to get rid of our custom stuff in KDE, we
> >> >> > > 
> >> >> > > hit
> >> >> > > 
> >> >> > > that issue when trying to build parts of KDE with FindQt4.cmake
> >> >> > > from
> >> >> > > 
> >> >> > > cmake.
> >> >> > > 
> >> >> > > 
> >> >> > > 
> >> >> > > Do you remember why this line was removed ?
> >> >> > > 
> >> >> > > What do you think about adding it again, as the attached patch
> >> >> > > does
> >> >> > > 
> >> >> > > ?
> >> >> > > 
> >> >> > > 
> >> >> > > 
> >> >> > > Alex
> >> >> > 
> >> >> > It was probably removed because I thought add_custom_command()
> >> >> > already
> >> >> > 
> >> >> > added the needed dependency information.
> >> >> > 
> >> >> > 
> >> >> > 
> >> >> > It should already have this:
> >> >> > 
> >> >> > mocable.h -> moc_mocable.cpp -> moc_mocable.o
> >> >> 
> >> >> This works if the generated moc file is listed as source file for a
> >> >> 
> >> >> target. In several places we did not do this, and relied instead on
> >> >> the
> >> >> 
> >> >> OBJECT_DEPENDS.
> >> >> 
> >> >> Ahh, this was in places where the moc file is generated from a cpp
> >> >> file,
> >> >> 
> >> >> which includes the moc file.
> >> >> 
> >> >> In those cases the OBJECT_DEPENDS makes it work.
> >> >> 
> >> >> 
> >> >> 
> >> >> We fixed this in the meantime by adding the generated moc file to the
> >> >> 
> >> >> source list (which is not too bad, since the developer explicitely
> >> >> 
> >> >> names the moc file, so it is ok).
> >> >> 
> >> >> 
> >> >> 
> >> >> So, I would like to have that dependency, but I'm unsure whether it
> >> >> 
> >> >> might have any unwanted side effects.
> >> > 
> >> > Ah, so for the case
> >> > 
> >> > mocable.h -> mocable.moc -> mocable.cpp (includes mocable.moc)
> >> > 
> >> > the mocable.moc is not listed in the sources of the target.
> >> > 
> >> > 
> >> > 
> >> > I can't think of any possible unwanted side effects.
> >> > 
> >> > I agree that we need to have this patch.
> >> > 
> >> > 
> >> > 
> >> > --
> >> > 
> >> > Clinton Stimpson
> >> > 
> >> > Elemental Technologies, Inc
> >> > 
> >> > Computational Simulation Software, LLC
> >> > 
> >> > www.csimsoft.com
> >> > 
> >> > --
> >> > 
> >> > 
> >> > 
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> >> > 
> >> > 
> >> > 
> >> > Visit other Kitware open-source projects at
> >> > 
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> >> > 
> >> > 
> >> > 
> >> > Please keep messages on-topic and check the CMake FAQ at:
> >> > 
> >> > http://www.cmake.org/Wiki/CMake_FAQ
> >> > 
> >> > 
> >> > 
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> >> > 
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> >> 
> >> If somebody pushes this to 'next' today or tomorrow, I'll make sure we
> >> 
> >> can get it into 2.8.9-rc2.
> > 
> > Too late now for 2.8.9 ?
> > 
> > Alex
> 
> Unless you tell me it's absolutely critical, and the fix is 99.9999%
> safe, then, yes, it's too late.
> 
> But 2.8.10 is right around the corner if you adopt the right viewpoint. :-)

Ok, this can wait until 2.8.10.

Can the branch EclipseAddSupportForJuno still make it into 2.8.9 ?
It improves the Eclipse generator by adding support for Eclipse Juno (the most 
recent one) and improves behaviour on Mac, and it should be completely safe.

Alex
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