How to separate the build and install steps

Right now:

catkin config --install-space /opt/ros/indigo
catkin build
...
catkin --install
sudo catkin build

Gets you this:

Error: Attempting to build a catkin workspace using build space: "..." but that build space's 
most recent configuration differs from the commanded one in ways which will cause problems.
Fix the following options or use `catkin clean -b` to remove the build space: 
 - install: False (stored) is not True (commanded)

In ros-install-osx, the desire not to run the entire build as root is dealt with by simply having /opt/ros/foo owned by the user rather than root, so everything is as the user (following the Homebrew model). But there are packaging and other use cases where separating the build and install steps is desirable. Is there truly something dangerous being blocked here, or does is it getting caught in a dragnet of potentially dangerous behaviours?

If the latter, can we put in an exemption that allows running just the install step on an already-built workspace?

[wjwwood]

Well it correctly warns you that building it without --install and then re-building it with --install may fail in unexpected ways. The first time goes like this:

• build pkg A without installing it
• source devel space of A
• build pkg B (which depends on A) without installing it
• etc…

The second time (if it let you) you’d get:

• build pkg A, installing this time
• source install space of A
• build pkg B (which depends on A), installing this time
• etc…

The problem with that is pkg B may not rebuild it’s binaries and libraries since no build configs or source files changed (even if you force a re-run of CMake), but the libraries it should link against have changed (which would break usage of RPATH for example), and ever generated code might reference the wrong thing (devel space of previous packages rather than their install spaces). So it’s best, when changing that option, to rebuild everything after cleaning.

The root issue, as I see it, is that you want to introduce the --install after building so you can do that as root, but that’s just not a good idea in my opinion because any other files created by the tool will then be owned by root. make does a pretty good job of avoiding this, but it’s still problematic with tools like pip and others.

[foodtooth]

Hi, is there anything new about this issue, or do I have to implement that “–sudo-install” option?