buildPython*: allow stdenv customization through <function>.override

pkgs/development/interpreters/python/mk-python-derivation.nix

@@ -4,6 +4,8 @@
   lib,
   config,
   python,
+  # Allow passing in a custom stdenv to buildPython*.override
+  stdenv,
   wrapPython,
   unzip,
   ensureNewerSourcesForZipFilesHook,
@@ -192,9 +194,6 @@ in
 
   doCheck ? true,
 
-  # Allow passing in a custom stdenv to buildPython*
-  stdenv ? python.stdenv,
-
   ...
 }@attrs:
 

pkgs/development/interpreters/python/python-packages-base.nix

@@ -45,21 +45,42 @@ let
       override = lib.mirrorFunctionArgs f.override (fdrv: makeOverridablePythonPackage (f.override fdrv));
     };
 
+  overrideStdenvCompat =
+    f:
+    lib.setFunctionArgs (
+      args:
+      if !(lib.isFunction args) && (args ? stdenv) then
+        # TODO: warn that `args ? stdenv` is deprecated (once in-tree usage is migrated)
+        f.override { stdenv = args.stdenv; } args
+      else
+        f args
+    ) (removeAttrs (lib.functionArgs f) [ "stdenv" ])
+    // {
+      # Intentionally drop the effect of overrideStdenvCompat when calling `buildPython*.override`.
+      inherit (f) override;
+    };
+
   mkPythonDerivation =
     if python.isPy3k then ./mk-python-derivation.nix else ./python2/mk-python-derivation.nix;
 
   buildPythonPackage = makeOverridablePythonPackage (
-    callPackage mkPythonDerivation {
-      inherit namePrefix; # We want Python libraries to be named like e.g. "python3.6-${name}"
-      inherit toPythonModule; # Libraries provide modules
-    }
+    overrideStdenvCompat (
+      callPackage mkPythonDerivation {
+        inherit namePrefix; # We want Python libraries to be named like e.g. "python3.6-${name}"
+        inherit toPythonModule; # Libraries provide modules
+        inherit (python) stdenv;
+      }
+    )
   );
 
   buildPythonApplication = makeOverridablePythonPackage (
-    callPackage mkPythonDerivation {
-      namePrefix = ""; # Python applications should not have any prefix
-      toPythonModule = x: x; # Application does not provide modules.
-    }
+    overrideStdenvCompat (
+      callPackage mkPythonDerivation {
+        namePrefix = ""; # Python applications should not have any prefix
+        toPythonModule = x: x; # Application does not provide modules.
+        inherit (python) stdenv;
+      }
+    )
   );
 
   # Check whether a derivation provides a Python module.

pkgs/development/interpreters/python/python2/mk-python-derivation.nix

@@ -4,6 +4,8 @@
   lib,
   config,
   python,
+  # Allow passing in a custom stdenv to buildPython*.override
+  stdenv,
   wrapPython,
   unzip,
   ensureNewerSourcesForZipFilesHook,
@@ -101,8 +103,6 @@
 }@attrs:
 
 let
-  inherit (python) stdenv;
-
   withDistOutput = lib.elem format [
     "pyproject"
     "setuptools"