Don't trigger the evaluation of apple-sdk in Linux stdenv

[zhaofengli]

During the Apple SDK revamp of #346043, cc-wrapper and bintools-wrapper were modified to automatically add a fallback SDK if $DEVELOPER_DIR is not set. However, because of the order of the && operands, apple-sdk is always evaluated even when it's not needed.

Let's flip the && operands so we only trigger the evaluation when targeting Darwin. This should speed things up too.

Example

Apply this simple patch:

diff --git a/pkgs/by-name/ap/apple-sdk/package.nix b/pkgs/by-name/ap/apple-sdk/package.nix
index 04b32f07a642..67e76d634d1c 100644
--- a/pkgs/by-name/ap/apple-sdk/package.nix
+++ b/pkgs/by-name/ap/apple-sdk/package.nix
@@ -46,6 +46,7 @@ let
     # This has to happen last.
     ++ [
       (callPackage ./common/run-build-phase-hooks.nix { })
+      (self: super: builtins.trace "SDK hash: ${super.src.outputHash}" super)
     ]
   );
 in

And watch everything explode on Linux while it tries to call fetchSDK with the bootstrap fetchurl:

$ nix-instantiate --system x86_64-linux -A hello
error:
       … while evaluating r
         at /home/zhaofeng/Git/nixpkgs/pkgs/top-level/default.nix:91:11:
           90|       (x: throwIfNot (lib.isFunction x) "All crossOverlays passed to nixpkgs must be functions.")
           91|       (r: r)
             |           ^
           92|       crossOverlays;

       … while evaluating cur
         at /home/zhaofeng/Git/nixpkgs/pkgs/stdenv/booter.nix:80:5:
           79|     in
           80|     cur;
             |     ^
           81|

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: function 'anonymous lambda' called with unexpected arguments 'version', 'pname', 'nativeBuildInputs', 'recursiveHash' and 'postFetch'
       at /home/zhaofeng/Git/nixpkgs/pkgs/build-support/fetchurl/boot.nix:7:1:
            6|
            7| {
             | ^
            8|   url ? builtins.head urls,

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/)
• Nixpkgs 25.11 Release Notes (or backporting 24.11 and 25.05 Nixpkgs Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
• NixOS 25.11 Release Notes (or backporting 24.11 and 25.05 NixOS Release notes)
  • (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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[reckenrode]

LGTM. Let’s backport this to 24.12 and 25.05.

[nixpkgs-ci]

Successfully created backport PR for release-24.11:

• [Backport release-24.11] Don't trigger the evaluation of apple-sdk in Linux stdenv #409629

[nixpkgs-ci]

Successfully created backport PR for release-25.05:

• [Backport release-25.05] Don't trigger the evaluation of apple-sdk in Linux stdenv #409630