llvmPackages.libcxx: use hasSharedLibraries instead of isStatic

[kuruczgy]

Split from #352629, as this should be a relatively uncontroversial bugfix that also makes sense on its own.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
  • riscv32-none-elf
• 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/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 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.

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[alyssais]

Huh — what's the difference between isStatic and hasSharedLibraries? When would one be true but not the other?

[kuruczgy]

@alyssais see this comment:

nixpkgs/lib/systems/default.nix

Lines 196 to 203 in a435bac

	# The difference between `isStatic` and `hasSharedLibraries` is mainly the
	# addition of the `staticMarker` (see make-derivation.nix). Some
	# platforms, like embedded machines without a libc (e.g. arm-none-eabi)
	# don't support dynamic linking, but don't get the `staticMarker`.
	# `pkgsStatic` sets `isStatic=true`, so `pkgsStatic.hostPlatform` always
	# has the `staticMarker`.
	isStatic = final.isWasi || final.isRedox;

[alyssais]

Ah, I see! So really we should basically always be checking hasSharedLibraries instead of isStatic?

[kuruczgy]

Ah, I see! So really we should basically always be checking hasSharedLibraries instead of isStatic?

Not sure in what other cases it needs to be checked, but yes, I believe hasSharedLibraries should often be more correct.

[alyssais]

Lots of packages check it to e.g. tell CMake not to try to build shared libraries.

[alyssais]

I think a rebase would fix OfBorg.

[alyssais]

This can go to master — it doesn't really rebuild anything.

[alyssais]

Would welcome PRs to update more isStatic checks to hasSharedLibraries. :)