Support package functions without named args

builtinModules/packages.nix

@@ -13,8 +13,11 @@ let
 
   genPkg = final: prev: name: pkg:
     let
+      args = functionArgs pkg;
+      noArgs = args == { };
+      pkg' = if noArgs then { pkgs }: pkg pkgs else pkg;
       dependsOnSelf = hasAttr name (functionArgs pkg);
-      dependsOnPkgs = (functionArgs pkg) ? pkgs;
+      dependsOnPkgs = noArgs || (args ? pkgs);
       selfOverride = {
         ${name} = prev.${name} or
           (throw "${name} depends on ${name}, but no existing ${name}.");
@@ -22,7 +25,7 @@ let
       overrides = optionalAttrs dependsOnSelf selfOverride
         // optionalAttrs dependsOnPkgs { pkgs = final.pkgs // selfOverride; };
     in
-    final.callPackage pkg overrides;
+    final.callPackage pkg' overrides;
   genPkgs = final: prev: pkgs:
     mapAttrs (name: genPkg final prev name) pkgs;
 in

misc/nameMockedPkgs.nix

@@ -14,6 +14,7 @@ let
       fargs = lib.functionArgs f;
       mock = lib.mapAttrs (_: _: throw "") (lib.filterAttrs (_: v: !v) fargs);
     in
+    assert fargs != { };
     f (mock // builtins.intersectAttrs fargs autoArgs // args);
 
   mockStdenv = real: stdenv: real.${stdenv} or (throw "") // {
@@ -22,7 +23,6 @@ let
   };
 in
 lib.fix (self: {
-  pkgs = self;
   lib = lib // { inherit callPackageWith; };
 
   callPackage = callPackageWith self;

tests/default.nix

@@ -170,6 +170,12 @@ in
     })
     (f: import f.packages.x86_64-linux.default);
 
+  package-no-named-args = test
+    (flakelight ./empty {
+      package = pkgs: pkgs.hello;
+    })
+    (f: f.packages.aarch64-linux.default.pname == "hello");
+
   package-prevent-recursion = test
     (flakelight ./empty {
       package = { hello }: hello;