Nixpkgs issues

[jonringer]

Tracking issue for nixpkgs related issues

Issues:

• Position missing for perl packages perlPackages: restore meta.position NixOS/nixpkgs#158856
• Position missing for many fonts, simple packages (which are largely just fetchers) fetchFromGitHub: fix meta NixOS/nixpkgs#158844
• elm packages missing position elmPackages: restore positions, use makeScope, cleanup NixOS/nixpkgs#160046
• dwarf-fortress-packages.themes lack prefixes

[AMDmi3]

I've rephrased the last issue.

The problem is not really missing prefixes - prefixes are just needed to distinguish specific realms of packages from others, which, being mixed together, are likely to cause conflicts. We can instead use categories for that as it's done for haskell and node modules.

The problem is that when a new category appears, we don't yet have a rule for it, and it immediately causes a lot of conflicts as it has already happened with the mentioned haskell and node modules.

I can handle this on Repology side by dropping nix packages which have category, unless there's a rule for it. However, there will be need to maintain a whitelist of categories which do not require prefixes

            category            | count 
--------------------------------+-------
 CuboCore                       |    22
 androidStudioPackages          |     3
 apacheHttpdPackages            |    20
 arcan                          |     8
 aspellDicts                    |    91
 bat-extras                     |     5
 beetsExternalPlugins           |     3
 bitscope                       |     8
 chickenPackages_4              |     2
 cinnamon                       |    23
 coqPackages                    |    73
 coreboot-toolchain             |     7
 cudaPackages                   |     9
 dhallPackages                  |     1
 dictdDBs                       |     2
 dotnetCorePackages             |     4
 dotnetPackages                 |    19
 driversi686Linux               |     8
 dwarf-fortress-packages        |    31
 eclipses                       |     9
 elasticsearchPlugins           |     8
 elmPackages                    |    11
 emacs27Packages                |  5353
 emscriptenPackages             |     4
 enlightenment                  |     8
 fcitx-engines                  |    12
 fdbPackages                    |     4
 fishPlugins                    |     9
 fusePackages                   |     1
 gawkextlib                     |    17
 gimpPlugins                    |     9
 glimpsePlugins                 |     9
 gnome                          |   111
 gnome2                         |    25
 gnomeExtensions                |   564
 gns3Packages                   |     2
 gnuradio3_8Packages            |     7
 gnuradio3_9Packages            |     1
 gnustep                        |     9
 graylogPlugins                 |    18
 greetd                         |     5
 gsignondPlugins                |     4
 gst_all_1                      |    11
 haskell                        |    16
 haskellPackages                | 16801
 haxePackages                   |     5
...

The problem with that solution is that we don't yet have a mechanism which would report that a new unhandled category appeared, so we'll silently lose some packages.

[AMDmi3]

Regarding the first two issues, btw, I've implemented the solution mentioned in #1225 (comment). After your changes it's no longer needed for nix_unstable, but it allowed to avoid dropping some packages in stable branches.