emacs: factor out elisp package override helpers (#341964)

pkgs/applications/editors/emacs/elisp-packages/elpa-devel-packages.nix

···
 
 self: let
 
-  markBroken = pkg: pkg.override {
-    elpaBuild = args: self.elpaBuild (args // {
-      meta = (args.meta or {}) // { broken = true; };
-    });
-  };
+  inherit (import ./lib-override-helper.nix pkgs)
+    markBroken
+    ;
 
   # Use custom elpa url fetcher with fallback/uncompress
   fetchurl = buildPackages.callPackage ./fetchelpa.nix { };

pkgs/applications/editors/emacs/elisp-packages/elpa-packages.nix

···
 
 self: let
 
-  markBroken = pkg: pkg.override {
-    elpaBuild = args: self.elpaBuild (args // {
-      meta = (args.meta or {}) // { broken = true; };
-    });
-  };
+  inherit (import ./lib-override-helper.nix pkgs)
+    markBroken
+    ;
 
   # Use custom elpa url fetcher with fallback/uncompress
   fetchurl = buildPackages.callPackage ./fetchelpa.nix { };

pkgs/applications/editors/emacs/elisp-packages/lib-override-helper.nix

···
+pkgs:
+
+rec {
+  buildWithGit =
+    pkg:
+    pkg.overrideAttrs (previousAttrs: {
+      nativeBuildInputs = previousAttrs.nativeBuildInputs or [ ] ++ [ pkgs.git ];
+    });
+
+  dontConfigure = pkg: pkg.overrideAttrs { dontConfigure = true; };
+
+  externalSrc =
+    pkg: epkg:
+    pkg.overrideAttrs (previousAttrs: {
+      inherit (epkg) src version;
+      propagatedUserEnvPkgs = previousAttrs.propagatedUserEnvPkgs or [ ] ++ [ epkg ];
+    });
+
+  fix-rtags = pkg: dontConfigure (externalSrc pkg pkgs.rtags);
+
+  markBroken =
+    pkg:
+    pkg.overrideAttrs (previousAttrs: {
+      meta = previousAttrs.meta or { } // {
+        broken = true;
+      };
+    });
+}

pkgs/applications/editors/emacs/elisp-packages/melpa-packages.nix

···
 
 { lib, pkgs }: variant: self:
 let
-  dontConfigure = pkg:
-    pkg.override (args: {
-      melpaBuild = drv: args.melpaBuild (drv // {
-        dontConfigure = true;
-      });
-    });
-
-  markBroken = pkg:
-    pkg.override (args: {
-      melpaBuild = drv: args.melpaBuild (drv // {
-        meta = (drv.meta or { }) // { broken = true; };
-      });
-    });
-
-  externalSrc = pkg: epkg:
-    pkg.override (args: {
-      melpaBuild = drv: args.melpaBuild (drv // {
-        inherit (epkg) src version;
-
-        propagatedUserEnvPkgs = [ epkg ];
-      });
-    });
-
-  buildWithGit = pkg: pkg.overrideAttrs (attrs: {
-    nativeBuildInputs =
-      (attrs.nativeBuildInputs or [ ]) ++ [ pkgs.git ];
-  });
-
-  fix-rtags = pkg: dontConfigure (externalSrc pkg pkgs.rtags);
+  inherit (import ./lib-override-helper.nix pkgs)
+    buildWithGit
+    dontConfigure
+    externalSrc
+    fix-rtags
+    markBroken
+    ;
 
   generateMelpa = lib.makeOverridable ({ archiveJson ? defaultArchive
                                        }: