[CMake] A small philosophical problem

[Carminati Federico]

Hello,
     I want to be able to build optionally static libs for my project.  
I have no problem to add custom targets and dependencies, this all  
works nicely. However I want to be able to install them if needed. So  
I define an installation rule and I label it as optional, as these  
files may or may not exist. cmake complains with the following message

WARNING: Target "TTherminator_a" has EXCLUDE_FROM_ALL set and will not  
be built by default but an install rule has been provided for it.   
CMake does not define behavior for this case.

I believe that this warning is justified if I do not lable the  
component as OPTIONAL, however if it is labelled as optional, the  
behaviour IS welll defined. The component is not there and it will not  
be installed. So I believe that in case of optional install targets  
the warning should not be there. BEst,

Federico Carminati
CERN-PH
1211 Geneva 23
Switzerland
Tel: +41 22 76 74959
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