"ROS" packages already in nixpkgs

[nim65s]

Hi,

Could we override some packages from the overlay to directly use those provided by nixpkgs, instead of trying to re-declare and re-build things from ROS ?

Context: I'm the maintainer (upstream + nixpkgs + ROS) of a few things (eg. eigenpy / hpp-fcl / pinocchio): pinocchio is in better shape in nixpkgs than in ROS. For example in nixpkgs we can enable the casadi optional dependency, while in ROS that's harder since casadi is not packaged in ubuntu.

Also, since pinocchio requires lot of RAM and time to build, I think it would be very beneficial for your build & cache infra :)

NB: I'm speaking of non-ROS-only packages, which are packaged in rosdistro. Maybe it make little or no difference for pure ROS packages, but version constraints might be harder.

[nim65s]

Hum, wait, that's already the case, isn't it ?
You're wonderful, thank you.

[nim65s]

Actually, that's half the case, this is why I was mislead in the first place:

$ nix repl
Lix 2.91.1
Type :? for help.
nix-repl> :lf github:lopsided98/nix-ros-overlay
Added 17 variables.

nix-repl> outputs.legacyPackages.x86_64-linux.humble.pinocchio                 
«derivation /nix/store/ka5slb3x93ky1k8s1i7710qdpbwlq1fi-ros-humble-pinocchio-2.6.21-r1.drv»

nix-repl> outputs.legacyPackages.x86_64-linux.humble.python3Packages.pinocchio
«derivation /nix/store/gac53bw2ryvinpyf40rfwc3b5mpkskgw-pinocchio-3.2.0.drv»

Pinocchio is both available as a C++ library and a python module, and, here, the 2.6.21r1 C++ library is from rosdistro, and the 3.2.0 python module from nixpkgs