1 files changed, 35 insertions, 0 deletions
diff --git a/nixpkgs/pkgs/build-support/writers/aliases.nix b/nixpkgs/pkgs/build-support/writers/aliases.nix
new file mode 100644
index 000000000000..fb108a6fd857
--- /dev/null
+++ b/nixpkgs/pkgs/build-support/writers/aliases.nix
@@ -0,0 +1,35 @@
+lib: prev:
+
+let
+  # Removing recurseForDerivation prevents derivations of aliased attribute
+  # set to appear while listing all the packages available.
+  removeRecurseForDerivations = alias: with lib;
+    if alias.recurseForDerivations or false then
+      removeAttrs alias ["recurseForDerivations"]
+    else alias;
+
+  # Disabling distribution prevents top-level aliases for non-recursed package
+  # sets from building on Hydra.
+  removeDistribute = alias: with lib;
+    if isDerivation alias then
+      dontDistribute alias
+    else alias;
+
+  # Make sure that we are not shadowing something from
+  # writers.
+  checkInPkgs = n: alias: if builtins.hasAttr n prev
+                          then throw "Alias ${n} is still in writers"
+                          else alias;
+
+  mapAliases = aliases:
+    lib.mapAttrs (n: alias: removeDistribute
+                             (removeRecurseForDerivations
+                              (checkInPkgs n alias)))
+                     aliases;
+
+in
+mapAliases ({
+  /* Cleanup before 22.05, Added 2021-12-11 */
+  writePython2 = "Python 2 is EOL and the use of writers.writePython2 is deprecated.";
+  writePython2Bin = "Python 2 is EOL and the use of writers.writePython2Bin is deprecated.";
+})