libpcl-dev breaks libvtk6-qt-dev on Ubuntu Focal

[matlabbe]

I will refer to issue explained here: introlab/rtabmap#557

In summary, in package.xml of rtabmap, it depends on both libpcl-all-dev and libvtk-qt. The problem is that libpcl-all-dev installs libpcl-dev which depends on libvtk7-dev on Ubuntu Focal, not libvtk6-dev. In rosdistro, if we specify libvtk-qt, it installs libvtk6-qt-dev on Focal, breaking libpcl-dev.

rosdistro/rosdep/base.yaml

Lines 4118 to 4143 in 504a87e

	libvtk-qt:
	arch: [vtk]
	debian:
	buster: [libvtk6-qt-dev]
	jessie: [libvtk5-qt4-dev]
	stretch: [libvtk6-qt-dev]
	wheezy: [libvtk5-qt4-dev]
	fedora: [vtk-qt]
	freebsd: [vtk6]
	gentoo: ['sci-libs/vtk[qt5,rendering]']
	opensuse: [vtk-qt]
	slackware: [VTK]
	ubuntu:
	'*': [libvtk6-qt-dev]
	lucid: [libvtk5-qt4-dev]
	maverick: [libvtk5-qt4-dev]
	natty: [libvtk5-qt4-dev]
	oneiric: [libvtk5-qt4-dev]
	precise: [libvtk5-qt4-dev]
	quantal: [libvtk5-qt4-dev]
	raring: [libvtk5-qt4-dev]
	saucy: [libvtk5-qt4-dev]
	trusty: [libvtk5-qt4-dev]
	utopic: [libvtk5-qt4-dev]
	vivid: [libvtk5-qt4-dev]
	wily: [libvtk5-qt4-dev]

Could rosdistro install libvtk7-qt-dev instead of libvtk6-qt-dev on Ubuntu 20.04, or will it break something else (packages really depending on libvtk6-qt-dev, though normally they would have to upgrade to latest vtk version)? I didn't do a pull request because I am not sure about the other distros, to which vtk version libpcl-dev is depending on.

[matlabbe]

I think I've found a solution. I should be able to remove libvtk-qt from package.xml, as libpcl-dev already installs indirectly the right vtk qt libraries. I'll close this for now, and re-open if it doesn't work.