Add ROS support

[nim65s]

Hi,

This is a first take at adding distributions from ROS: https://ros.org/

Adding more info (at least authors / maintainers / licenses) would require fetching package.xml from individual packages, but maybe I can automate that in a repository managed by the ROS project, which would provide flat file per distro version for repology to ingest.

[AMDmi3]

Note there's only 10% intersection with other repos. Apart from that I don't see any major problems with package versions or names, but dropped packages due to lacking releases are a concern.

[AMDmi3]

For the note, it may make sense not to add EoLed repos of that would simplify code (e.g. by dropping legacy conditions for them).

[nim65s]

I did not have to write anything specific for these old things, and it seem to work so I included them. But I don't really need those.

[nim65s]

Note there's only 10% intersection with other repos.

Yes, those repos are mostly specific to robotics applications, and mostly not packaged elsewhere.

They are available on Nix through https://github.com/lopsided98/nix-ros-overlay, on Arch through AUR, and on conda through https://robostack.github.io/, so this might change in the future.

dropped packages due to lacking releases are a concern.

I'm not sure to understand what do you mean here. There are also dropped packages in older versions of other distributions too, right ? Anyways, it would be totally fine for me to just include the latest versions of ROS, if this may help. We currently have only 4 active ones, as Iron support has ended: https://docs.ros.org/

[AMDmi3]

I'm not sure to understand what do you mean here. There are also dropped packages in older versions of other distributions too, right?

If you mean that some other parsers may skip packages - AFAIR there may be some, but we strive to either fix or remove these, not add new incomplete parsers. There are 3 branches which skip packages - no release, no version and bitbucket link. Bitbucket case should just skip adding a recipe link, this is tolerable. Other cases, where do these come from, why's there an entry in the yaml, but part of the info is missing? May currently complete packages turn into this state?

[nim65s]

Packages without releases are only available from source. This is often the case during the process of indexing a new package before the release repository can be created, eg. ros/rosdistro#43915. Complete packages can turn into this state, for example when some ubuntu dependency is no longer available in new ubuntu version, eg: ros/rosdistro#40091, but only on rolling, as other ones are tied on ubuntu versions.

Packages without version are those which fail to build on platform transition (same as latter case from above), eg. ros/rosdistro#32036. In the same way, complete packages can turn into this state, but only on rolling.

[AMDmi3]

We cannot add rolling then, incomplete repository content and flapping packages are show stoppers. I suggest to generate a complete dataset based on recipes and not affected by outside factors.