Add setupcfg2nix and supporting infrastructure

pkgs/build-support/build-setupcfg/default.nix

@@ -0,0 +1,23 @@
+# Build a python package from info made available by setupcfg2nix.
+#
+# * src: The source of the package.
+# * info: The package information generated by setupcfg2nix.
+# * meta: Standard nixpkgs metadata.
+# * application: Whether this package is a python library or an
+#   application which happens to be written in python.
+pythonPackages: { src, info, meta ? {}, application ? false }: let
+  build = if application
+    then pythonPackages.buildPythonApplication
+  else pythonPackages.buildPythonPackage;
+in build {
+  inherit (info) pname version;
+
+  inherit src meta;
+
+  nativeBuildInputs = map (p: pythonPackages.${p}) (
+    (info.setup_requires or []) ++
+    (info.tests_require or []));
+
+  propagatedBuildInputs = map (p: pythonPackages.${p})
+    (info.install_requires or []);
+}

pkgs/development/tools/setupcfg2nix/default.nix

@@ -0,0 +1,19 @@
+{ buildSetupcfg, fetchFromGitHub, lib }:
+
+buildSetupcfg rec {
+  info = import ./info.nix;
+  src = fetchFromGitHub {
+    owner = "target";
+    repo = "setupcfg2nix";
+    rev = info.version;
+    sha256 = "1zn9njpzwhwikrirgjlyz6ys3xr8gq61ry8blmnpscqvhsdhxcs6";
+  };
+  application = true;
+  meta = {
+    description = "Generate nix expressions from setup.cfg for a python package.";
+    homepage = https://github.com/target/setupcfg2nix;
+    license = lib.licenses.mit;
+    platforms = lib.platforms.all;
+    maintainers = [ lib.maintainers.shlevy ];
+  };
+}

pkgs/development/tools/setupcfg2nix/info.nix

@@ -0,0 +1,7 @@
+{
+  pname = ''setupcfg2nix'';
+  version = ''1.1.0'';
+  install_requires = [
+    ''setuptools''
+  ];
+}

pkgs/top-level/all-packages.nix

@@ -7230,6 +7230,8 @@ with pkgs;
     pythonPackages = python3Packages;
   };
 
+  setupcfg2nix = python3Packages.callPackage ../development/tools/setupcfg2nix {};
+
   # These pyside tools do not provide any Python modules and are meant to be here.
   # See ../development/python-modules/pyside/default.nix for details.
   pysideApiextractor = callPackage ../development/python-modules/pyside/apiextractor.nix { };

pkgs/top-level/python-packages.nix

@@ -66,6 +66,9 @@ let
     toPythonModule = x: x; # Application does not provide modules.
   }));
 
+  # See build-setupcfg/default.nix for documentation.
+  buildSetupcfg = import ../build-support/build-setupcfg self;
+
   graphiteVersion = "1.0.2";
 
   fetchPypi = makeOverridable( {format ? "setuptools", ... } @attrs:
@@ -133,6 +136,7 @@ in {
   inherit fetchPypi callPackage;
   inherit hasPythonModule requiredPythonModules makePythonPath disabledIf;
   inherit toPythonModule toPythonApplication;
+  inherit buildSetupcfg;
 
   # helpers