Initial nix packaging

[nim65s]

Hello !

This PR includes:

1. a CMake fix for use cases where users (or package managers) set eg. -DCMAKE_INSTALL_LIBDIR=/an/absolute/path
2. a default.nix file which create a basic visp package in nix, and a flake.nix file to easily build and use this package. At some point, we will want to move this default.nix to https://github.com/NixOS/nixpkgs/, and just override the src attribute in the flake to use the local version instead.
3. a github action to test this nix setup.

I have a few questions:

• did I miss important dependencies / options ?
• visp do not compile correctly with ogre v14.2.5. Is this known ? What should we do about it ?
• contributing guidelines provide a "Copyright Assignment Agreement for an Individual Contributor". I am not in an individual position, but with CNRS. What should we do about that ?

Also, nix macos packaging is not done yet. I'll probably be able to find some time to deal with this, but not today, and maybe not this week.

[fspindle]

Just for my understanding to what does lib refer?

[fspindle]

We could add the following dependencies

• libjpeg-turbo
• pkg-config for usage without cmake
• libX11 if not the case by default
• librealsense

[nim65s]

lib is a collection of nix code inside nixpkgs, with both helpers and common data: https://github.com/nixOS/nixpkgs/blob/master/lib/README.md

Here, I'm only using it for the following:

nix-repl> pkgs.lib.licenses.gpl2Plus
{ deprecated = false; free = true; fullName = "GNU General Public License v2.0 or later"; redistributable = true; shortName = "gpl2Plus"; spdxId = "GPL-2.0-or-later"; url = "https://spdx.org/licenses/GPL-2.0-or-later.html"; }

nix-repl> pkgs.lib.maintainers.nim65s
{ email = "[email protected]"; github = "nim65s"; githubId = 131929; keys = [ ... ]; matrix = "@gsaurel:laas.fr"; name = "Guilhem Saurel"; }

[fspindle]

@nim65s Thanks for this nice contribution.

did I miss important dependencies / options ?

I added other deps in the code review

visp do not compile correctly with ogre v14.2.5. Is this known ? What should we do about it ?

No. I need to check.

contributing guidelines provide a "Copyright Assignment Agreement for an Individual Contributor". I am not in an individual position, but with CNRS. What should we do about that ?

I don't know. I will investigate and let you know...

[fspindle]

@nim65s Thanks Guilhem.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 45.59%. Comparing base (68deeca) to head (69c444a).
Report is 9 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1416   +/-   ##
=======================================
  Coverage   45.59%   45.59%           
=======================================
  Files        1082     1082           
  Lines      109215   109215           
  Branches    18758    18758           
=======================================
  Hits        49792    49792           
  Misses      59423    59423           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.