Description of changes

This PR defines a function lib.applyToOverridable that make sure that an overridable (an attribute set one can override) behaves when updating its attributes directly (i.e. not by overriding).

Without it, the updating will be lost once the overridable is overridden. For example, ((lib.extendDerivation true { ans = 42; } pkgs.hello).override { }).ans throws error: attribute 'ans' missing. This is relevant when applying extendDerivation to a package produced by stdenv.mkDerivation.

Packages produced by many language-specific build helpers suffers from such overrideAttrs misbehave. For example, pkgs.python3Packages.six.updateScript evaluates successfully, but (pkgs.python311Packages.six.overrideAttrs { }).updateScript throws error: attribute 'updateScript' missing. I'm not planning to fix them here, as they can be improved through lib.extendMkDerivationModified in the future, which internally calls lib.applyToOverridable. It sounds awkward to change them twice.

This is split from #234651

This depends on #265710 for lib.mirrorFunctionArgs.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• 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.