[CMake] Re: Re: FindQt4 in 2.4.8 bug

[Hendrik Sattler]

Quoting Bill Hoffman <bill.hoffman at kitware.com>:
> OK, I get it now...   So, the FIND_* stuff will set a value if it is
> NOTFOUND.  However, the set command will not.  I am thinking it should.
>     I am not sure what that will break, but it would be consistent with
> FIND_*.
>
> This should not be a problem if you start from a clean build tree for
> FindQt4.cmake, as QT_INCLUDE_DIR will never get put in the cache as
> NOTFOUND by the current FindQt4.cmake.   So, I think this is something
> we can fix in CMake 2.6.    Feel free to create a feature request, "set
> CACHE should set NOTFOUND variables".

Let's say a library is optional. A current script cannot see the  
difference anymore between "library not found on earlier run" and "I  
did not search for it, yet". SET is well-documented about CACHE and  
FORCE behaviour. Don't break that as you can always use
  if (NOT DEFINED VAR)
    set (VAR "foo" CACHE ...... FORCE)

HS