python: unsupported platforms check and buildPythonApplication support

explanations/python-unsupported-platforms.md

@@ -0,0 +1 @@
+The python builder automatically sets `meta.platforms` to that of the interpreter, so the only reason to set it is to further limit the supported platforms to a subset of those supported by the python interpreter.

lib/default.nix

@@ -107,6 +107,7 @@ rec {
       lib.genAttrs pythonPackageSetNames (pythonName:
         prev.${pythonName}.override (oldOverrides: {
           packageOverrides = lib.composeExtensions (oldOverrides.packageOverrides or idOverlay) (final: prev: {
+            buildPythonApplication = wrapFunctionWithChecks prev.buildPythonApplication check;
             buildPythonPackage = wrapFunctionWithChecks prev.buildPythonPackage check;
           });
         })

overlays/python-inconsistent-interpreters.nix

@@ -9,21 +9,28 @@ let
       checkInputs = drvArgs.checkInputs or [];
       runtimeInputs = checkInputs ++ propagatedBuildInputs;
       inputPythonInterpreters = map (p: p.pythonModule) (builtins.filter (p: p ? pythonModule) runtimeInputs);
-      allPythonInterpreters = lib.unique (inputPythonInterpreters ++ [ drv.pythonModule ]);
+      allPythonInterpreters = lib.unique (inputPythonInterpreters ++ lib.optionals (drv ? pythonModule) [ drv.pythonModule ]);
     in
       lib.singleton {
         name = "python-inconsistent-interpreters";
         cond = builtins.length allPythonInterpreters > 1;
         msg =
           let
             allPythonNames = map (p: p.name) allPythonInterpreters;
-            sources = [
-              "buildPythonPackage"
+            sources = if drv ? pythonModule
+            then [ "buildPythonPackage"
             ] ++ lib.optionals (builtins.any (p: p.pythonModule or drv.pythonModule != drv.pythonModule) propagatedBuildInputs) [
               "propagatedBuildInputs"
             ] ++ lib.optionals (builtins.any (p: p.pythonModule or drv.pythonModule != drv.pythonModule) checkInputs) [
               "checkInputs"
+            ]
+            else [ "buildPythonApplication"
+            ] ++ lib.optionals (builtins.length (lib.unique(map (p: p.pythonModule) propagatedBuildInputs)) >= 2) [
+              "propagatedBuildInputs"
+            ] ++ lib.optionals (builtins.length (lib.unique(map (p: p.pythonModule) checkInputs)) >= 2) [
+              "checkInputs"
             ];
+
           in ''
             Between ${lib.concatStringsSep " and " sources}, this derivation seems
             to be simultaneously trying to use packages from multiple different Python package sets.

overlays/python-unsupported-platforms.nix

@@ -0,0 +1,30 @@
+final: prev:
+let
+  inherit (prev) lib;
+  inherit (import ../lib { inherit lib; }) checkBuildPythonPackageFor;
+
+  checkDerivation = drvArgs: drv:
+    let
+      # We can access python with the `pythonModule` attribute of `buildPythonPackage`
+      # derivations, but it is not so simple with `buildPythonApplication`. Here we rely on the
+      # performance hack in nixpkgs/pkgs/development/interpreters/python/mk-python-derivation.nix
+      # which injects python into propagatedBuildInputs.
+      python = lib.lists.last (builtins.filter (p: p ? pythonVersion) drv.propagatedBuildInputs);
+      drvPlatforms = drvArgs.meta.platforms or [ ];
+      unsupportedPlatforms = lib.lists.subtractLists python.meta.platforms drvPlatforms;
+    in lib.singleton {
+      name = "python-unsupported-platforms";
+      cond = (unsupportedPlatforms != [ ]) || (lib.lists.naturalSort drvPlatforms == lib.lists.naturalSort python.meta.platforms);
+      msg = if unsupportedPlatforms != [ ] then ''
+        The following meta.platforms are not supported by the ${python} interpreter:
+          [ ${builtins.toString unsupportedPlatforms} ]
+      '' else ''
+        The meta.platforms attribute is set to the same value by default.
+      '';
+      locations = [
+        (builtins.unsafeGetAttrPos "platforms" python.meta)
+        (builtins.unsafeGetAttrPos "platforms" drvArgs.meta)
+      ];
+    };
+in
+  checkBuildPythonPackageFor checkDerivation final prev

run-tests.py

@@ -277,6 +277,19 @@ def __iter__(self):
             ],
         )
 
+        yield make_test_rule(
+            'python-unsupported-platforms',
+            [
+                'platforms-all',
+                "build-python-application-platforms-all",
+            ],
+            [
+                'platforms-linux',
+                'unspecified',
+                "build-python-application-platforms-linux",
+            ]
+        )
+
         yield make_test_rule(
             "python-include-tests",
             [
@@ -291,9 +304,11 @@ def __iter__(self):
             [
                 "mixed-1",
                 "mixed-2",
+                "build-python-application-mixed",
             ],
             [
                 "normal",
+                "build-python-application-normal",
             ],
         )
 

tests/default.nix

@@ -25,6 +25,7 @@
   python-imports-check-typo = pkgs.recurseIntoAttrs (pkgs.python3.pkgs.callPackage ./python-imports-check-typo { });
   python-include-tests = pkgs.recurseIntoAttrs (pkgs.python3.pkgs.callPackage ./python-include-tests { });
   python-inconsistent-interpreters = pkgs.recurseIntoAttrs (pkgs.python3.pkgs.callPackage ./python-inconsistent-interpreters { });
+  python-unsupported-platforms = pkgs.recurseIntoAttrs (pkgs.python3.pkgs.callPackage ./python-unsupported-platforms { });
   stale-substitute = pkgs.recurseIntoAttrs (pkgs.callPackage ./stale-substitute { });
   unclear-gpl = pkgs.recurseIntoAttrs (pkgs.callPackage ./unclear-gpl { });
   unnecessary-parallel-building = pkgs.recurseIntoAttrs (pkgs.callPackage ./unnecessary-parallel-building { });

tests/python-inconsistent-interpreters/build-python-application-mixed.nix

@@ -0,0 +1,13 @@
+{ buildPythonApplication
+, python37Packages
+, python39Packages
+}:
+
+buildPythonApplication rec {
+  name = "package";
+
+  propagatedBuildInputs = [
+    python37Packages.numpy
+    python39Packages.scipy
+  ];
+}

tests/python-inconsistent-interpreters/build-python-application-normal.nix

@@ -0,0 +1,13 @@
+{ buildPythonApplication
+, numpy
+, scipy
+}:
+
+buildPythonApplication rec {
+  name = "package";
+
+  propagatedBuildInputs = [
+    numpy
+    scipy
+  ];
+}

tests/python-inconsistent-interpreters/default.nix

@@ -5,7 +5,9 @@
   # positive cases
   mixed-1 = callPackage ./mixed-1.nix { };
   mixed-2 = callPackage ./mixed-2.nix { };
+  build-python-application-mixed = callPackage ./build-python-application-mixed.nix { };
 
   # negative cases
   normal = callPackage ./normal.nix { };
+  build-python-application-normal = callPackage ./build-python-application-normal.nix { };
 }

tests/python-unsupported-platforms/build-python-application-platforms-all.nix

@@ -0,0 +1,12 @@
+{ lib
+, buildPythonApplication
+}:
+
+buildPythonApplication rec {
+  pname = "package";
+  version = "0.1.0";
+
+  meta = with lib; {
+    platforms = platforms.all;
+  };
+}

tests/python-unsupported-platforms/build-python-application-platforms-linux.nix

@@ -0,0 +1,12 @@
+{ lib
+, buildPythonApplication
+}:
+
+buildPythonApplication rec {
+  pname = "package";
+  version = "0.1.0";
+
+  meta = with lib; {
+    platforms = platforms.linux;
+  };
+}

tests/python-unsupported-platforms/default.nix

@@ -0,0 +1,13 @@
+{ callPackage
+}:
+
+{
+  # positive cases
+  platforms-all = callPackage ./platforms-all.nix { };
+  build-python-application-platforms-all = callPackage ./build-python-application-platforms-all.nix { };
+
+  # negative cases
+  platforms-linux = callPackage ./platforms-linux.nix { };
+  unspecified = callPackage ./unspecified.nix { };
+  build-python-application-platforms-linux = callPackage ./build-python-application-platforms-linux.nix { };
+}

tests/python-unsupported-platforms/platforms-all.nix

@@ -0,0 +1,12 @@
+{ lib
+, buildPythonPackage
+}:
+
+buildPythonPackage rec {
+  pname = "package";
+  version = "0.1.0";
+
+  meta = with lib; {
+    platforms = platforms.all;
+  };
+}

tests/python-unsupported-platforms/platforms-linux.nix

@@ -0,0 +1,12 @@
+{ lib
+, buildPythonPackage
+}:
+
+buildPythonPackage rec {
+  pname = "package";
+  version = "0.1.0";
+
+  meta = with lib; {
+    platforms = platforms.linux;
+  };
+}

tests/python-unsupported-platforms/unspecified.nix

@@ -0,0 +1,7 @@
+{ buildPythonPackage
+}:
+
+buildPythonPackage rec {
+  pname = "package";
+  version = "0.1.0";
+}