Migrate this to use slightly more constrainted monkeypatching

The primary benefit of this is that it'll work when you have a single project using both setuptools-rust as well as cffi.

Author: alex

setup.cfg

@@ -31,7 +31,8 @@ setup_requires = setuptools>=41; wheel; setuptools_scm[toml]>=3.4.3
 distutils.commands =
     check_rust=setuptools_rust.check:check_rust
     clean_rust=setuptools_rust:clean_rust
-    build_ext=setuptools_rust:build_ext
     build_rust=setuptools_rust:build_rust
     test_rust=setuptools_rust:test_rust
     tomlgen_rust=setuptools_rust:tomlgen_rust
+distutils.setup_keywords =
+    rust_extensions=setuptools_rust.setuptools_ext:rust_extensions

setuptools_rust/__init__.py

@@ -1,8 +1,6 @@
 from __future__ import print_function, absolute_import
 
-from . import patch
 from .build import build_rust
-from .build_ext import build_ext
 from .check import check_rust
 from .clean import clean_rust
 from .extension import RustExtension
@@ -16,10 +14,6 @@
     "Strip",
     "check_rust",
     "clean_rust",
-    "build_ext",
     "build_rust",
     "test_rust",
 )
-
-
-patch.monkey_patch_dist(build_ext)

setuptools_rust/build_ext.py

@@ -0,0 +1,124 @@
+from distutils import log
+from distutils.command.check import check
+from distutils.command.clean import clean
+from distutils.command.install import install
+
+from setuptools.command.build_ext import build_ext
+
+try:
+    from wheel.bdist_wheel import bdist_wheel
+except ImportError:
+    bdist_wheel = None
+
+
+def add_rust_extension(dist):
+    build_ext_base_class = dist.cmdclass.get('build_ext', build_ext)
+
+    class build_ext_rust_extension(build_ext_base_class):
+        def run(self):
+            if self.distribution.rust_extensions:
+                log.info("running build_rust")
+                build_rust = self.get_finalized_command("build_rust")
+                build_rust.inplace = self.inplace
+                build_rust.run()
+
+            build_ext_base_class.run(self)
+    dist.cmdclass['build_ext'] = build_ext_rust_extension
+
+    clean_base_class = dist.cmdclass.get('clean', clean)
+
+    class clean_rust_extension(clean_base_class):
+        def run(self):
+            clean_base_class.run(self)
+            if not self.dry_run:
+                self.run_command("clean_rust")
+    dist.cmdclass['clean'] = clean_rust_extension
+
+    check_base_class = dist.cmdclass.get('check', check)
+
+    class check_rust_extension(check_base_class):
+        def run(self):
+            check_base_class.run(self)
+            self.run_command("check_rust")
+    dist.cmdclass["check"] = check_rust_extension
+
+    install_base_class = dist.cmdclass.get('install', install)
+
+    # this is required because, install directly access distribution's
+    # ext_modules attr to check if dist has ext modules
+    class install_rust_extension(install_base_class):
+        def finalize_options(self):
+            ext_modules = self.distribution.ext_modules
+
+            # all ext modules
+            mods = []
+            if self.distribution.ext_modules:
+                mods.extend(self.distribution.ext_modules)
+            if self.distribution.rust_extensions:
+                mods.extend(self.distribution.rust_extensions)
+
+                scripts = []
+                for ext in self.distribution.rust_extensions:
+                    scripts.extend(ext.entry_points())
+
+                if scripts:
+                    if not self.distribution.entry_points:
+                        self.distribution.entry_points = {"console_scripts": scripts}
+                    else:
+                        ep_scripts = self.distribution.entry_points.get("console_scripts")
+                        if ep_scripts:
+                            for script in scripts:
+                                if script not in ep_scripts:
+                                    ep_scripts.append(scripts)
+                        else:
+                            ep_scripts = scripts
+
+                        self.distribution.entry_points["console_scripts"] = ep_scripts
+
+            self.distribution.ext_modules = mods
+
+            install_base_class.finalize_options(self)
+
+            # restore ext_modules
+            self.distribution.ext_modules = ext_modules
+    dist.cmdclass["install"] = install_rust_extension
+
+    if bdist_wheel is not None:
+        bdist_wheel_base_class = dist.cmdclass.get("bdist_wheel", bdist_wheel)
+
+        # this is for console entries
+        class bdist_wheel_rust_extension(bdist_wheel_base_class):
+            def finalize_options(self):
+                scripts = []
+                for ext in self.distribution.rust_extensions:
+                    scripts.extend(ext.entry_points())
+
+                if scripts:
+                    if not self.distribution.entry_points:
+                        self.distribution.entry_points = {"console_scripts": scripts}
+                    else:
+                        ep_scripts = self.distribution.entry_points.get("console_scripts")
+                        if ep_scripts:
+                            for script in scripts:
+                                if script not in ep_scripts:
+                                    ep_scripts.append(scripts)
+                        else:
+                            ep_scripts = scripts
+
+                        self.distribution.entry_points["console_scripts"] = ep_scripts
+
+                bdist_wheel_base_class.finalize_options(self)
+        dist.cmdclass["bdist_wheel"] = bdist_wheel_rust_extension
+
+
+
+def rust_extensions(dist, attr, value):
+    assert attr == "rust_extensions"
+
+    orig_has_ext_modules = dist.has_ext_modules
+    dist.has_ext_modules = lambda: (
+        orig_has_ext_modules() or bool(dist.rust_extensions)
+    )
+
+    if dist.rust_extensions:
+        add_rust_extension(dist)