Merge pull request #156751 from NixOS/backport-156587-to-release-21.11

[Backport release-21.11] Improve check that evaluation does not depend on the Nixpkgs path

pkgs/development/ruby-modules/bundled-common/functions.nix

@@ -76,7 +76,7 @@ in rec {
           bundledByPath = true;
           name = gemName;
           version = version;
-          outPath = path;
+          outPath = "${path}";
           outputs = [ "out" ];
           out = res;
           outputName = "out";

pkgs/top-level/nixpkgs-basic-release-checks.nix

@@ -19,15 +19,8 @@ pkgs.runCommand "nixpkgs-release-checks" { src = nixpkgs; buildInputs = [nix]; }
         exit 1
     fi
 
-    # Make sure that derivation paths do not depend on the Nixpkgs path.
-    mkdir $TMPDIR/foo
-    ln -s $(readlink -f $src) $TMPDIR/foo/bar
-    p1=$(nix-instantiate $src --dry-run -A firefox --show-trace)
-    p2=$(nix-instantiate $TMPDIR/foo/bar --dry-run -A firefox --show-trace)
-    if [ "$p1" != "$p2" ]; then
-        echo "Nixpkgs evaluation depends on Nixpkgs path ($p1 vs $p2)!"
-        exit 1
-    fi
+    src2=$TMPDIR/foo
+    cp -rd $src $src2
 
     # Check that all-packages.nix evaluates on a number of platforms without any warnings.
     for platform in ${pkgs.lib.concatStringsSep " " supportedSystems}; do
@@ -37,7 +30,25 @@ pkgs.runCommand "nixpkgs-release-checks" { src = nixpkgs; buildInputs = [nix]; }
             --show-trace --argstr system "$platform" \
             --arg config '{ allowAliases = false; }' \
             -qa --drv-path --system-filter \* --system \
-            "''${opts[@]}" 2>&1 >/dev/null | tee eval-warnings.log
+            "''${opts[@]}" 2> eval-warnings.log > packages1
+
+        s1=$(sha1sum packages1 | cut -c1-40)
+        echo $s1
+
+        nix-env -f $src2 \
+            --show-trace --argstr system "$platform" \
+            --arg config '{ allowAliases = false; }' \
+            --option experimental-features 'no-url-literals' \
+            -qa --drv-path --system-filter \* --system \
+            "''${opts[@]}" > packages2
+
+        s2=$(sha1sum packages2 | cut -c1-40)
+
+        if [[ $s1 != $s2 ]]; then
+            echo "Nixpkgs evaluation depends on Nixpkgs path"
+            diff packages1 packages2
+            exit 1
+        fi
 
         if [ -s eval-warnings.log ]; then
             echo "Nixpkgs on $platform evaluated with warnings, aborting"