Index: bdist_wininst.py
===================================================================
--- bdist_wininst.py	(revision 82643)
+++ bdist_wininst.py	(working copy)
@@ -1,8 +1,20 @@
 """distutils.command.bdist_wininst
 
 Implements the Distutils 'bdist_wininst' command: create a windows installer
-exe-program."""
+exe-program.
 
+bdist_wininst produces two types of distributions:
+1. binary extension installers
+2. pure python code installers
+
+Installers with binary code can only be produced on windows system, because
+build requires recompilation of extension C code, which can only be made by
+the same compiler python itself is compiled with, i.e. Visual Studio.
+
+Binary extension installers embed the name of the platform in filename.
+Installers with pure python code always have a "win32" suffix.
+"""
+
 __revision__ = "$Id$"
 
 import sys
@@ -15,7 +27,6 @@
 from distutils.dir_util import remove_tree
 from distutils.errors import DistutilsOptionError, DistutilsPlatformError
 from distutils import log
-from distutils.util import get_platform
 
 class bdist_wininst (Command):
 
@@ -24,8 +35,8 @@
     user_options = [('bdist-dir=', None,
                      "temporary directory for creating the distribution"),
                     ('plat-name=', 'p',
-                     "platform name to embed in generated filenames "
-                     "(default: %s)" % get_platform()),
+                     "target platform for C extensions, can be win-amd64, win-ia64"
+                     "or win32 (default: autodetect)"),
                     ('keep-temp', 'k',
                      "keep the pseudo-installation tree around after " +
                      "creating the distribution archive"),
@@ -63,6 +74,10 @@
 
     def initialize_options (self):
         self.bdist_dir = None
+        # supported values for C extensions
+        # win-amd64 (64bit Windows on AMD64 (aka x86_64, Intel64, EM64T, etc)
+        # win-ia64 (64bit Windows on Itanium)
+        # win32
         self.plat_name = None
         self.keep_temp = 0
         self.no_target_compile = 0
@@ -116,7 +131,7 @@
 
 
     def run (self):
-        if (sys.platform != "win32" and
+        if (not self.plat_name.startswith("win") and
             (self.distribution.has_ext_modules() or
              self.distribution.has_c_libraries())):
             raise DistutilsPlatformError \
@@ -304,15 +319,23 @@
 
     def get_installer_filename(self, fullname):
         # Factored out to allow overriding in subclasses
+
+        # pure Python packages always have win32 extension
+        # required for crossplatform behaviour
+        if not self.distribution.has_ext_modules()
+            and not self.distribution.has_c_libraries():
+            basename = "%s.%s" % (fullname, "win32")
+        else:
+            basename = "%s.%s" % (fullname, self.plat_name)
+
         if self.target_version:
             # if we create an installer for a specific python version,
             # it's better to include this in the name
             installer_name = os.path.join(self.dist_dir,
-                                          "%s.%s-py%s.exe" %
-                                           (fullname, self.plat_name, self.target_version))
+                                          "%s-py%s.exe" %
+                                           (basename, self.target_version))
         else:
-            installer_name = os.path.join(self.dist_dir,
-                                          "%s.%s.exe" % (fullname, self.plat_name))
+            installer_name = os.path.join(self.dist_dir, "%s.exe" % basename)
         return installer_name
     # get_installer_filename()