vlc system package can be broken by source installation

[Karl-Philipp Richter]

A `vlc` source installation with `./bootstrap && ./configure && make && sudo make install` can break the system package because `/usr/bin/vlc` uses shared libraries from `/usr/local`. It should be possible to have multiple installations besides a running system package installation.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: vlc 2.2.2-5
Uname: Linux 4.5.0-040500-generic x86_64
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CurrentDesktop: Unity
Date: Thu Apr 28 21:33:53 2016
InstallationDate: Installed on 2015-12-12 (138 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
SourcePackage: vlc
UpgradeStatus: Upgraded to xenial on 2016-03-14 (45 days ago)

[Sebastian Ramacher (s-ramacher)]

Well, yes, that's the purpose of /usr/local. If you screw with it, you get to keep the pieces.

[Karl-Philipp Richter (krichter722)]

> Well, yes, that's the purpose of /usr/local.
It's just an installation prefix of many possible. Installations into `/usr/local` should provide files for binaries of that prefix and installations into `/usr` (source installation or packages) should provide files for binaries in that prefix. There's no reason why an installation into `/usr/local` is breaking something and that's the reason why so many programs don't have any trouble with source installations in `/usr/local` and binary packages installed into `/usr`.

If you don't support it or don't have the resources to support it's good not great.

[Sebastian Ramacher (s-ramacher)]

/usr/local is special as defined by the FHS: https://www.debian.org/doc/packaging-manuals/fhs/fhs-2.3.html#USRLOCALLOCALHIERARCHY

[Karl-Philipp Richter (krichter722)]

> /usr/local is special as defined by the FHS: https://www.debian.org/doc/packaging-manuals/fhs/fhs-2.3.html#USRLOCALLOCALHIERARCHY
I agree that it's special :) Yet, it doesn't answer the question whether packages are allowed to be broken by installations into /usr/local. I don't seem to find a resource which answers that question. Since that's not a launchpad.net discussion, I opened http://askubuntu.com/questions/779430/are-system-packages-installed-into-usr-allowed-to-be-broken-by-source-installat to figure this out.