pkgs/top-level: use lib.systems.equals for crossSystem

Fixes otherwise equivalent systems being treated as different by
packages that compare `stdenv.*Platform`s using `==` operator.

1 files changed, 47 insertions, 0 deletions

diff --git a/pkgs/test/top-level/default.nix b/pkgs/test/top-level/default.nix
new file mode 100644
index 0000000000000..fdb9fe09a88b8
--- /dev/null
+++ b/pkgs/test/top-level/default.nix
@@ -0,0 +1,47 @@
+{ lib, pkgs, ... }:
+let
+  nixpkgsFun = import ../../top-level;
+in
+lib.recurseIntoAttrs {
+  platformEquality =
+    let
+      configsLocal = [
+        # crossSystem is implicitly set to localSystem.
+        {
+          localSystem = { system = "x86_64-linux"; };
+        }
+        {
+          localSystem = { system = "aarch64-linux"; };
+          crossSystem = null;
+        }
+        # Both systems explicitly set to the same string.
+        {
+          localSystem = { system = "x86_64-linux"; };
+          crossSystem = { system = "x86_64-linux"; };
+        }
+        # Vendor and ABI inferred from system double.
+        {
+          localSystem = { system = "aarch64-linux"; };
+          crossSystem = { config = "aarch64-unknown-linux-gnu"; };
+        }
+      ];
+      configsCross = [
+        # GNU is inferred from double, but config explicitly requests musl.
+        {
+          localSystem = { system = "aarch64-linux"; };
+          crossSystem = { config = "aarch64-unknown-linux-musl"; };
+        }
+        # Cross-compile from AArch64 to x86-64.
+        {
+          localSystem = { system = "aarch64-linux"; };
+          crossSystem = { system = "x86_64-unknown-linux-gnu"; };
+        }
+      ];
+
+      pkgsLocal = map nixpkgsFun configsLocal;
+      pkgsCross = map nixpkgsFun configsCross;
+    in
+    assert lib.all (p: p.buildPlatform == p.hostPlatform) pkgsLocal;
+    assert lib.all (p: p.buildPlatform != p.hostPlatform) pkgsCross;
+    pkgs.emptyFile;
+}