Add script for generate sdist package for Windows platform in PyPI (pytorch#559)

* Add script to generate a mock torch source distributed package for Windows on PyPI

* Resolve review comments

* Resolve review comments

* Resolve review comments

* Resolve review comments

* Rename bash file name to a more meaningful one

* Resolve review comments

* Update packaging/windows/build_pypi_pkg_download_proxy/setup.py

Co-authored-by: Joe Zhu <[email protected]>
Co-authored-by: Nikita Shulga <[email protected]>

Author: gunandrose4u

packaging/windows/build_pypi_pkg_download_proxy/generate_win_pypi_pkg_download_proxy.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+set -ex
+
+TORCH_VER=$1
+SETUP_FILE="setup.py"
+REPLACE_KEYWORD="{{GENERATE_TORCH_PKG_VER}}"
+
+mkdir torch
+cp $SETUP_FILE torch/
+cd torch
+sed -i "s/$REPLACE_KEYWORD/$TORCH_VER/g" $SETUP_FILE
+python $SETUP_FILE sdist
+
+echo "Generate package under torch/dist"

packaging/windows/build_pypi_pkg_download_proxy/setup.py

@@ -0,0 +1,75 @@
+import sys
+import subprocess
+
+import setuptools.command.install
+from setuptools import find_packages, setup
+import wheel.bdist_wheel
+
+pkg_name = "torch"
+pkg_ver = "{{GENERATE_TORCH_PKG_VER}}"
+torch_download_url = "https://download.pytorch.org/whl/torch_stable.html"
+
+python_min_version = (3, 6, 1)
+python_min_version_str = '.'.join((str(num) for num in python_min_version))
+
+install_requires = [
+   'pip',
+]
+
+class install_torch(setuptools.command.install.install):
+    def run(self):
+        if sys.platform == 'win32' and sys.maxsize.bit_length() == 31:
+            raise UserWarning("We don't support Python x86." \
+                "Please install Python x64 instead.")
+
+        raise UserWarning(
+            f"Can not download torch binary from {torch_download_url}." \
+            f"Please visit {torch_download_url} for more details."
+        )
+
+class bdist_wheel(wheel.bdist_wheel.bdist_wheel):
+    def run(self):
+        if sys.platform == 'win32' and sys.maxsize.bit_length() != 31:
+            subprocess.check_call(
+                [sys.executable, '-m', 'pip', 'download',
+                f'{pkg_name}==={pkg_ver}', '-f', torch_download_url,
+                '--platform', 'win_amd64', '--only-binary=:all:',
+                '--no-deps', '-d', self.dist_dir])
+        else:
+            raise UserWarning("Cannot find a binary package of PyTorch for your Python environment.")
+
+setup(
+    name=pkg_name,
+    version=pkg_ver,
+    description=("Tensors and Dynamic neural networks in "
+                    "Python with strong GPU acceleration"),
+    cmdclass={
+        'bdist_wheel': bdist_wheel,
+        'install': install_torch,
+    },
+    packages=find_packages(),
+    url='https://pytorch.org/',
+    download_url='https://github.com/pytorch/pytorch/tags',
+    author='PyTorch Team',
+    author_email='[email protected]',
+    python_requires='>={}'.format(python_min_version_str),
+    install_requires=install_requires,
+    # PyPI package information.
+    classifiers=[
+        'Development Status :: 5 - Production/Stable',
+        'Intended Audience :: Developers',
+        'Intended Audience :: Education',
+        'Intended Audience :: Science/Research',
+        'License :: OSI Approved :: BSD License',
+        'Topic :: Scientific/Engineering',
+        'Topic :: Scientific/Engineering :: Mathematics',
+        'Topic :: Scientific/Engineering :: Artificial Intelligence',
+        'Topic :: Software Development',
+        'Topic :: Software Development :: Libraries',
+        'Topic :: Software Development :: Libraries :: Python Modules',
+        'Programming Language :: C++',
+        'Programming Language :: Python :: 3',
+    ],
+    license='BSD-3',
+    keywords='pytorch machine learning',
+)