[CMake] Does FIND_PACKAGE ignore REQUIRED and QUIET in Config mode ?

[Brad King]

Alexander Neundorf wrote:
> On Friday 05 September 2008, Yann Cointepas wrote:
>> 1) Why do I need Foo_FIND_QUIET in FooConfig.cmake ?
>> First, I would like to display a message with the Foo version found if
>> QUIET is not used.

Okay.

>> 2) Why do I need Foo_FIND_REQUIRED in FooConfig.cmake ?
>> FooConfig.cmake will be packaged and installed on various systems (in a
>> Foo-devel package). Therefore, even if FooConfig.cmake is found, I need to
>> check that its mandatory dependencies are found too before setting
>> Foo_FOUND. For instance, I have a mandatory dependency on Boost and I would
>> like to have the following code in FooConfig.cmake:
> 
> Ok, this makes sense. 

I disagree.  The fact that FooConfig.cmake was loaded means that Foo
*was* found.  It is up to the module to report other information for
consumption by the project.  Perhaps the project finding Foo just wants
to load some documentation files from it and doesn't care about its
linking dependencies.  For this reason the find_package command in
Config mode defines "found" to mean that the module was found and
loaded.  It is going to set Foo_FOUND to true after loading
FooConfig.cmake no matter what the module does (unless it has a syntax
error).  Setting it inside the module will have no effect (though the
fatal error message will prevent the overall configuration from succeeding).

I do not recommend searching for required dependencies inside
"FooConfig.cmake".  The process that put it there in the first place
should have hard-coded inside it the locations of all dependencies.  If
it comes with a system package file (like a .deb), then that file should
have a dependency on the boost package and know where it will be
installed.  If it comes from the user having built and installed Foo,
then that build/install process should have found boost on the machine
already.  Using a different boost could lead to problems, so the
location should be hard-coded.

> Brad, any objections to set these two variables always, also in Config mode ?
> If not I can do that if you're not faster.

It doesn't hurt to have them available.  Please send me a proposed patch.

Thanks,
-Brad