From 4fa991a680ee8d479e23d1474de1ac5b331c3026 Mon Sep 17 00:00:00 2001
From: Sergei Zimmerman <xokdvium@proton.me>
Date: Thu, 29 May 2025 22:35:50 +0000
Subject: [PATCH] flake: Restore `packaging-overriding` check

The underlying bug seems to have been fixed in diffoscope 293 [1] [2].
Our nixpkgs input has 295.

[1]: https://github.com/NixOS/nixpkgs/pull/393381#issuecomment-2766703347
[2]: https://diffoscope.org/news/diffoscope-292-released/
---
 flake.nix | 40 ++++++++++++++++++----------------------
 1 file changed, 18 insertions(+), 22 deletions(-)

diff --git a/flake.nix b/flake.nix
index a8759d042..de9244b5c 100644
--- a/flake.nix
+++ b/flake.nix
@@ -233,28 +233,24 @@
             This shouldn't build anything significant; just check that things
             (including derivations) are _set up_ correctly.
           */
-          # Disabled due to a bug in `testEqualContents` (see
-          # https://github.com/NixOS/nix/issues/12690).
-          /*
-            packaging-overriding =
-              let
-                pkgs = nixpkgsFor.${system}.native;
-                nix = self.packages.${system}.nix;
-              in
-              assert (nix.appendPatches [ pkgs.emptyFile ]).libs.nix-util.src.patches == [ pkgs.emptyFile ];
-              if pkgs.stdenv.buildPlatform.isDarwin then
-                lib.warn "packaging-overriding check currently disabled because of a permissions issue on macOS" pkgs.emptyFile
-              else
-                # If this fails, something might be wrong with how we've wired the scope,
-                # or something could be broken in Nixpkgs.
-                pkgs.testers.testEqualContents {
-                  assertion = "trivial patch does not change source contents";
-                  expected = "${./.}";
-                  actual =
-                    # Same for all components; nix-util is an arbitrary pick
-                    (nix.appendPatches [ pkgs.emptyFile ]).libs.nix-util.src;
-                };
-          */
+          packaging-overriding =
+            let
+              pkgs = nixpkgsFor.${system}.native;
+              nix = self.packages.${system}.nix;
+            in
+            assert (nix.appendPatches [ pkgs.emptyFile ]).libs.nix-util.src.patches == [ pkgs.emptyFile ];
+            if pkgs.stdenv.buildPlatform.isDarwin then
+              lib.warn "packaging-overriding check currently disabled because of a permissions issue on macOS" pkgs.emptyFile
+            else
+              # If this fails, something might be wrong with how we've wired the scope,
+              # or something could be broken in Nixpkgs.
+              pkgs.testers.testEqualContents {
+                assertion = "trivial patch does not change source contents";
+                expected = "${./.}";
+                actual =
+                  # Same for all components; nix-util is an arbitrary pick
+                  (nix.appendPatches [ pkgs.emptyFile ]).libs.nix-util.src;
+              };
         }
         // (lib.optionalAttrs (builtins.elem system linux64BitSystems)) {
           dockerImage = self.hydraJobs.dockerImage.${system};