Update Python to 3.13.3 and add support to Windows on ARM64. (#1477)

Update Python to 3.13.0 and add support to Windows on AMD64. Rewrite
packaging of pywin32 because it is no longer shipped via separate binary
installers, but has migrated to use pip.

scripts/update_python.py

@@ -8,12 +8,13 @@
 http://storage.google.com/webassembly.
 
 We only supply binaries for windows and macOS, but we do it very different ways for those two OSes.
+On Linux, we depend on the system version of python.
 
 Windows recipe:
-  1. Download the "embeddable zip file" version of python from python.org
-  2. Remove .pth file to work around https://bugs.python.org/issue34841
-  3. Download and install pywin32 in the `site-packages` directory
-  4. Re-zip and upload to storage.google.com
+  1. Download precompiled version of python from NuGet package manager,
+     either the package "python" for AMD64, or "pythonarm64" for ARM64.
+  2. Set up pip and install pywin32 and psutil via pip for emrun to work.
+  3. Re-zip and upload to storage.google.com
 
 macOS recipe:
   1. Clone cpython
@@ -32,27 +33,35 @@ import sys
 from subprocess import check_call
 from zip import unzip_cmd, zip_cmd
 
-version = '3.9.2'
+version = '3.13.3'
 major_minor_version = '.'.join(version.split('.')[:2])  # e.g. '3.9.2' -> '3.9'
-download_url = 'https://www.nuget.org/api/v2/package/python/%s' % version
 # This is not part of official Python version, but a repackaging number appended by emsdk
 # when a version of Python needs to be redownloaded.
-revision = '4'
+revision = '0'
 
-pywin32_version = '227'
-pywin32_base = 'https://github.com/mhammond/pywin32/releases/download/b%s/' % pywin32_version
+PSUTIL = 'psutil==7.0.0'
 
 upload_base = 'gs://webassembly/emscripten-releases-builds/deps/'
 
 
+# Detects whether current python interpreter architecture is ARM64 or AMD64
+# If running AMD64 python on an ARM64 Windows, this still intentionally returns AMD64
+def find_python_arch():
+    import sysconfig
+    arch = sysconfig.get_platform().lower()
+    if 'amd64' in arch:
+        return 'amd64'
+    if 'arm64' in arch:
+        return 'arm64'
+    raise f'Unknown Python sysconfig platform "{arch}" (neither AMD64 or ARM64)'
+
+
 def make_python_patch():
-    pywin32_filename = 'pywin32-%s.win-amd64-py%s.exe' % (pywin32_version, major_minor_version)
-    filename = 'python-%s-amd64.zip' % (version)
-    out_filename = 'python-%s-%s-amd64+pywin32.zip' % (version, revision)
-    if not os.path.exists(pywin32_filename):
-        url = pywin32_base + pywin32_filename
-        print('Downloading pywin32: ' + url)
-        urllib.request.urlretrieve(url, pywin32_filename)
+    python_arch = find_python_arch()
+    package_name = 'pythonarm64' if python_arch == 'arm64' else 'python'
+    download_url = f'https://www.nuget.org/api/v2/package/{package_name}/{version}'
+    filename = f'python-{version}-win-{python_arch}.zip'
+    out_filename = f'python-{version}-{revision}-win-{python_arch}.zip'
 
     if not os.path.exists(filename):
         print(f'Downloading python: {download_url} to {filename}')
@@ -62,19 +71,17 @@ def make_python_patch():
     check_call(unzip_cmd() + [os.path.abspath(filename)], cwd='python-nuget')
     os.remove(filename)
 
-    os.mkdir('pywin32')
-    rtn = subprocess.call(unzip_cmd() + [os.path.abspath(pywin32_filename)], cwd='pywin32')
-    assert rtn in [0, 1]
+    src_dir = os.path.join('python-nuget', 'tools')
+    python_exe = os.path.join(src_dir, 'python.exe')
+    check_call([python_exe, '-m', 'ensurepip', '--upgrade'])
+    check_call([python_exe, '-m', 'pip', 'install', 'pywin32==310', '--no-warn-script-location'])
+    check_call([python_exe, '-m', 'pip', 'install', PSUTIL])
 
-    os.mkdir(os.path.join('python-nuget', 'lib'))
-    shutil.move(os.path.join('pywin32', 'PLATLIB'), os.path.join('python-nuget', 'toolss', 'Lib', 'site-packages'))
-
-    check_call(zip_cmd() + [os.path.join('..', '..', out_filename), '.'], cwd='python-nuget/tools')
+    check_call(zip_cmd() + [os.path.join('..', '..', out_filename), '.'], cwd=src_dir)
     print('Created: %s' % out_filename)
 
     # cleanup if everything went fine
     shutil.rmtree('python-nuget')
-    shutil.rmtree('pywin32')
 
     if '--upload' in sys.argv:
       upload_url = upload_base + out_filename
@@ -92,7 +99,7 @@ def build_python():
         check_call(['brew', 'install', 'openssl', 'xz', 'pkg-config'])
         if platform.machine() == 'x86_64':
             prefix = '/usr/local'
-            min_macos_version = '10.11'
+            min_macos_version = '11.0'
         elif platform.machine() == 'arm64':
             prefix = '/opt/homebrew'
             min_macos_version = '11.0'
@@ -113,7 +120,9 @@ def build_python():
         osname = 'linux'
 
     src_dir = 'cpython'
-    if not os.path.exists(src_dir):
+    if os.path.exists(src_dir):
+      check_call(['git', 'fetch'], cwd=src_dir)
+    else:
       check_call(['git', 'clone', 'https://github.com/python/cpython'])
     check_call(['git', 'checkout', 'v' + version], cwd=src_dir)
 
@@ -143,7 +152,7 @@ def build_python():
 
     # Install psutil module. This is needed by emrun to track when browser
     # process quits.
-    check_call([pybin, pip, 'install', 'psutil'])
+    check_call([pybin, pip, 'install', PSUTIL])
 
     dirname = 'python-%s-%s' % (version, revision)
     if os.path.isdir(dirname):