prevent in-source build?

[KrisThielemans]

The superbuild situation is somewhat confusing if where sources and builds are located. This gets worse if an in-source build is used. I suggest we error out if this is attempted. This can be done like here.

[rijobro]

I think erroring out is definitely a good idea, as it might help out less experienced CMakers

[paskino]

I believe that at least boost is built in source. Do you really want to error out?

[KrisThielemans]

we can/should build boost out-of-source as well. from another project, something like this should work

cd $BUILDPATH
$SRCDIR/bootstrap.sh --prefix=$INSTALLDIR
cd $SRCDIR
$BUILDPATH/b2 --build-dir=$BUILDPATH --prefix=$INSTALLDIR install

possibly these lines are overcomplicated, but you get the idea.

[KrisThielemans]

but in any case the suggestion above is for the SuperBuild itself, not for the content.

[paskino]

Ah, I had totally misunderstood that point. Then I agree.