[cmake-developers] Roadmap to CMake 3.0

[Alexander Neundorf]

On Monday 14 October 2013, Brad King wrote:
> On 10/13/2013 6:03 AM, Alexander Neundorf wrote:
...
> > I'd like to remove the --find-package mode, which was my attempt to make
> > cmake packages easier to use by non-cmake projects.
> > The idea was that you can use cmake --find-package JPEG similar to
> > pkg-config, i.e. call it from handwritten makefiles or autoconf, and it
> > prints the include dirs, link dirs and libs to link to stdout so they
> > are handed as options to the compiler.
> > To do that, it is/was relying on a set of standard variables
> > (Foo_LIBRARIES, Foo_INCLUDE_DIRS and some slight variations) being set
> > by Find-modules/Config files.
> > Since it was recently decided that it is fine to recommend using imported
> > target names directly and not to set the standard variables anymore, I
> > don't see how I could improve this in the future.
> > So instead I'd like to remove it instead of keeping a somewhat broken,
> > sometimes working feature around. which is not used widely.
> 
> Can't the --find-package mode evaluate the locations of targets named
> in the _LIBRARIES variables?  In general it will have to evaluate full
> generator expressions too.  I thought the idea of --find-package was
> to do all the transformations that CMake would do before putting the
> targets on the command line and then hand the result back.

Yes, that was the idea, but I can't rely anymore on a Foo_LIBRARIES variable 
(or a slight variation) being set after a successful find_package(Foo):
http://lists.kde.org/?l=kde-core-devel&m=138198795723680&w=2
I.e. in the future there will be Find-modules which typically export one of
(Foo|FOO)_(LIBRARIES|LIBRARY), some Config.cmake files which do that too, and 
a big number, probably majority, of Config.cmake files, which do not export 
such variables.

The only chance I see would be to simply collect all library targets and 
return what they provide, but this doesn't feel good. I would have much 
prefered using a clear interface like the Foo_LIBRARIES variable.

Alex