Issue #7833: Ext. modules built using distutils on Windows no longer get a manifest

Lib/distutils/msvc9compiler.py

@@ -627,15 +627,7 @@ class MSVCCompiler(CCompiler) :
                     self.library_filename(dll_name))
                 ld_args.append ('/IMPLIB:' + implib_file)
 
-            # Embedded manifests are recommended - see MSDN article titled
-            # "How to: Embed a Manifest Inside a C/C++ Application"
-            # (currently at http://msdn2.microsoft.com/en-us/library/ms235591(VS.80).aspx)
-            # Ask the linker to generate the manifest in the temp dir, so
-            # we can embed it later.
-            temp_manifest = os.path.join(
-                    build_temp,
-                    os.path.basename(output_filename) + ".manifest")
-            ld_args.append('/MANIFESTFILE:' + temp_manifest)
+            self.manifest_setup_ldargs(output_filename, build_temp, ld_args)
 
             if extra_preargs:
                 ld_args[:0] = extra_preargs
@@ -653,21 +645,54 @@ class MSVCCompiler(CCompiler) :
             # will still consider the DLL up-to-date, but it will not have a
             # manifest.  Maybe we should link to a temp file?  OTOH, that
             # implies a build environment error that shouldn't go undetected.
-            if target_desc == CCompiler.EXECUTABLE:
-                mfid = 1
-            else:
-                mfid = 2
-                # Remove references to the Visual C runtime
-                self._remove_visual_c_ref(temp_manifest)
-            out_arg = '-outputresource:%s;%s' % (output_filename, mfid)
-            try:
-                self.spawn(['mt.exe', '-nologo', '-manifest',
-                            temp_manifest, out_arg])
-            except DistutilsExecError as msg:
-                raise LinkError(msg)
+            mfinfo = self.manifest_get_embed_info(target_desc, ld_args)
+            if mfinfo is not None:
+                mffilename, mfid = mfinfo
+                out_arg = '-outputresource:%s;%s' % (output_filename, mfid)
+                try:
+                    self.spawn(['mt.exe', '-nologo', '-manifest',
+                                mffilename, out_arg])
+                except DistutilsExecError as msg:
+                    raise LinkError(msg)
         else:
             log.debug("skipping %s (up-to-date)", output_filename)
 
+    def manifest_setup_ldargs(self, output_filename, build_temp, ld_args):
+        # If we need a manifest at all, an embedded manifest is recommended.
+        # See MSDN article titled
+        # "How to: Embed a Manifest Inside a C/C++ Application"
+        # (currently at http://msdn2.microsoft.com/en-us/library/ms235591(VS.80).aspx)
+        # Ask the linker to generate the manifest in the temp dir, so
+        # we can check it, and possibly embed it, later.
+        temp_manifest = os.path.join(
+                build_temp,
+                os.path.basename(output_filename) + ".manifest")
+        ld_args.append('/MANIFESTFILE:' + temp_manifest)
+
+    def manifest_get_embed_info(self, target_desc, ld_args):
+        # If a manifest should be embedded, return a tuple of
+        # (manifest_filename, resource_id).  Returns None if no manifest
+        # should be embedded.  See http://bugs.python.org/issue7833 for why
+        # we want to avoid any manifest for extension modules if we can)
+        for arg in ld_args:
+            if arg.startswith("/MANIFESTFILE:"):
+                temp_manifest = arg.split(":", 1)[1]
+                break
+        else:
+            # no /MANIFESTFILE so nothing to do.
+            return None
+        if target_desc == CCompiler.EXECUTABLE:
+            # by default, executables always get the manifest with the
+            # CRT referenced.
+            mfid = 1
+        else:
+            # Extension modules try and avoid any manifest if possible.
+            mfid = 2
+            temp_manifest = self._remove_visual_c_ref(temp_manifest)
+        if temp_manifest is None:
+            return None
+        return temp_manifest, mfid
+
     def _remove_visual_c_ref(self, manifest_file):
         try:
             # Remove references to the Visual C runtime, so they will
@@ -676,6 +701,8 @@ class MSVCCompiler(CCompiler) :
             # runtimes are not in WinSxS folder, but in Python's own
             # folder), the runtimes do not need to be in every folder
             # with .pyd's.
+            # Returns either the filename of the modified manifest or
+            # None if no manifest should be embedded.
             manifest_f = open(manifest_file)
             try:
                 manifest_buf = manifest_f.read()
@@ -688,9 +715,18 @@ class MSVCCompiler(CCompiler) :
             manifest_buf = re.sub(pattern, "", manifest_buf)
             pattern = "<dependentAssembly>\s*</dependentAssembly>"
             manifest_buf = re.sub(pattern, "", manifest_buf)
+            # Now see if any other assemblies are referenced - if not, we 
+            # don't want a manifest embedded.
+            pattern = re.compile(
+                r"""<assemblyIdentity.*?name=(?:"|')(.+?)(?:"|')"""
+                r""".*?(?:/>|</assemblyIdentity>)""", re.DOTALL)
+            if re.search(pattern, manifest_buf) is None:
+                return None
+
             manifest_f = open(manifest_file, 'w')
             try:
                 manifest_f.write(manifest_buf)
+                return manifest_file
             finally:
                 manifest_f.close()
         except IOError: