qt: include qttranslations properly

[K900]

Description of changes

Qt loads its own translations from a hardcoded path, and those are used (among other things) for determining RTL layout preferences in applications, so they are definitely something we want to have.

This adds a qtbase/qttools rebuild to the chain, but it's fast enough that it's probably fine.

Another approach would be to load translation paths from the environment, and inject it in wrapQtAppsHook, but that seems like more complexity for very questionable build time savings.

Fixes #86054. Fixes #240101.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 23.11 Release Notes (or backporting 23.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

[K900]

Also something like this will also need to be done for Qt6, I just started looking into 5 because the original reported issue was that Plasma isn't handling RTL correctly.

[mahmoudajawad]

The reported issue: #240101

Thanks for your time and effort, @K900.

[K900]

Drafting for now to clean up the workarounds all over the tree.

[K900]

Verified all the affected packages build and run except stellarium (still building qtwebengine-6) and valentina (builds, but crashes on startup, same on master).

[K900]

Fixed qt6.qtwebengine and Stellarium.

[NickCao]

Can we skip the bootstrapping like just build qttranslations without qtbase?

[K900]

No, it needs qttools to actually generate the final files.

[NickCao]

I'm happy with the changes. Waiting for others' opinions.

[Mindavi]

Is this ? null needed?

[K900]

I think it will break baseScope but I moved things around a bit since the last time I tried. I'll have to double check.

[Mindavi]

Haven't tested but the diff seems fine. I don't know that much about the scopes part, but presumably it's now tested and at least fixes some of the LTR/RTL issues

[wineee]

@ofborg build qt6.qtwebengine

[K900]

I'm just going to merge this before we accumulate more treewide horkage.

[alyssais]

Since this change, it's not possible to use qt5.qttranslations, or anything that depends on it, in nativeBuildInputs when cross compiling. For example, pkgsCross.aarch64-multiplatform.pkgsBuildHost.qt5.qttranslations fails to build:

this derivation will be built:
  /nix/store/rfgxh3b2abdncfxyf5xhiwv9x2r35cad-qttranslations-5.15.10.drv
qttranslations> building '/nix/store/rfgxh3b2abdncfxyf5xhiwv9x2r35cad-qttranslations-5.15.10.drv'
qttranslations> Error: detected mismatched Qt dependencies:
qttranslations>     /nix/store/bnc68g66zdygbri398vwvq90s92l8xvl-qtbase-5.15.10-dev
qttranslations>     /nix/store/ddmypadxkl61f68lp8vif42rqp6ym3nm-qtbase-5.15.10-dev
error: build of '/nix/store/rfgxh3b2abdncfxyf5xhiwv9x2r35cad-qttranslations-5.15.10.drv' failed

This worked before this change, and is orthogonal to cross compiling qt itself — pkgsBuildHost.qt5.qttranslations should be exactly the same as pkgsBuildBuild.qt5.qttranslations, but somehow isn't any more.

[Artturin]

#269756