Use pyproject.toml for build requirements

Simplifies `setup.py`.
Cythonizes always when installed from source.
Required `pip>=10.0` to install from source.
Older pips will still be able to install from wheels.

MANIFEST.in

@@ -1 +1,2 @@
+include pyproject.toml
 recursive-include greedy *.h *.cpp *.pxd *.pyx

greedy/descent.pyx

@@ -1,7 +1,6 @@
 # distutils: language = c++
 # distutils: include_dirs = greedy/src/
 # distutils: sources = greedy/src/descent.cpp
-# distutils: language_level = 3
 
 # Copyright 2019 D-Wave Systems Inc.
 #

pyproject.toml

@@ -0,0 +1,8 @@
+[build-system]
+requires = [
+    "setuptools>=42.0.0",       # PEP-420 support, PEP-517/518 support
+    "wheel>=0.30.0",            # limited python api support
+    "cython>=0.29.23,<3.0",
+    "numpy==1.19.4",
+]
+build-backend = "setuptools.build_meta"

requirements.txt

@@ -1,3 +1,7 @@
 numpy==1.19.4
 dimod==0.9.14
 cython==0.29.21
+
+# build
+wheel>=0.30.0
+setuptools>=56.2.0

setup.py

@@ -1,63 +1,51 @@
+# Copyright 2021 D-Wave Systems Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 import os
-from io import open
-from setuptools import setup, find_packages, Extension
+
+from setuptools import setup, Extension
 from setuptools.command.build_ext import build_ext
+from Cython.Build import cythonize
+import numpy
 
 
-class cythonizing_build_ext(build_ext):
-    """Cython extensions adaptive build: cythonize if possible, include numpy
-    headers, add custom compile/link flags."""
+class build_ext_with_args(build_ext):
+    """Add compiler-specific compile/link flags."""
 
-    # Custom extension compile/link flags
     extra_compile_args = {
         'msvc': ['/std:c++14'],
         'unix': ['-std=c++11'],
     }
 
     extra_link_args = {
         'msvc': [],
-        'unix': [],
+        'unix': ['-std=c++11'],
     }
 
     def build_extensions(self):
-        # try using cython if available, fallback to using pre-cythonized
-        # files (if they exist; if not, ultimately fail)
-        try:
-            from Cython.Build import cythonize
-
-            # cythonization step will remove this flag needed by setuptools
-            _needs_stub = [ext._needs_stub for ext in self.extensions]
-
-            self.extensions = cythonize(self.extensions)
-
-            # restore _needs_stub flags for setuptools
-            for ext, ns in zip(self.extensions, _needs_stub):
-                ext._needs_stub = ns
-
-        except ImportError:
-            # cython not available, assume cythonized cpp files exist
-            for ext in self.extensions:
-                ext.sources = [source.replace(".pyx", ".cpp") for source in ext.sources]
-
-        # add compiler/linker flags
         compiler = self.compiler.compiler_type
 
         compile_args = self.extra_compile_args[compiler]
         for ext in self.extensions:
             ext.extra_compile_args = compile_args
+            print(dir(ext))
 
-        link_args = self.extra_compile_args[compiler]
+        link_args = self.extra_link_args[compiler]
         for ext in self.extensions:
             ext.extra_compile_args = link_args
 
-        build_ext.build_extensions(self)
-
-    def finalize_options(self):
-        build_ext.finalize_options(self)
-
-        # add numpy include files
-        import numpy
-        self.include_dirs.append(numpy.get_include())
+        super().build_extensions()
 
 
 # Load package info, without importing the package
@@ -77,20 +65,10 @@ def finalize_options(self):
     'test': ['coverage', 'mock', 'parameterized', 'dwave-system>=1.0.0'],
 }
 
-# Setup (extension build) requirements
-setup_requires = ['numpy>=1.16.0,<2.0.0']
-
-# We distribute cythonized source, so cython is not required
-# for install (build) from package, but allow manual override via env var
-USE_CYTHON = os.getenv('USE_CYTHON', False)
-
-if USE_CYTHON:
-    setup_requires.append('cython>=0.29.12')
-
 extensions = [Extension(
     name='greedy.descent',
-    sources=['./greedy/descent.pyx'],
-    include_dirs=['./greedy/src/']
+    sources=['greedy/descent.pyx'],
+    include_dirs=[numpy.get_include()]
 )]
 
 classifiers = [
@@ -118,10 +96,9 @@ def finalize_options(self):
     packages=packages,
     python_requires=python_requires,
     install_requires=install_requires,
-    setup_requires=setup_requires,
     extras_require=extras_require,
-    ext_modules=extensions,
-    cmdclass={'build_ext': cythonizing_build_ext},
+    ext_modules=cythonize(extensions),
+    cmdclass={'build_ext': build_ext_with_args},
     classifiers=classifiers,
     zip_safe=False,
 )