PluginDownloader: replace automatic 2to3 step with a simple warning

The previous heuristic runs into false positives when imports are merged in __init__.py

More broadly though, it's unlikely automatic 2to3 is particularly useful in 2022 - plugins that were written ~10 years ago are unlikely to work even if syntax errors are fixed.

plugins/PluginDownloader/plugin.py

@@ -121,11 +121,11 @@ class GithubRepository(GitRepository):
         assert directory is not None, \
                 'No valid directory in supybot.directories.plugins.'
 
+        possibly_incompatible = False
         try:
             assert archive.getmember(prefix + dirname).isdir(), \
                 'This is not a valid plugin (it is a file, not a directory).'
 
-            run_2to3 = minisix.PY3
             for file in archive.getmembers():
                 if file.name.startswith(prefix + dirname):
                     extractedFile = archive.extractfile(file)
@@ -140,41 +140,17 @@ class GithubRepository(GitRepository):
                         os.mkdir(newFileName)
                     else:
                         with open(newFileName, 'ab') as fd:
-                            reload_imported = False
                             for line in extractedFile.readlines():
-                                if minisix.PY3:
-                                    if b'import reload' in line:
-                                        reload_imported = True
-                                    elif not reload_imported and \
-                                            b'reload(' in line:
-                                        fd.write(b'from importlib import reload\n')
-                                        reload_imported = True
+                                if file.name.endswith('__init__.py') and \
+                                        line.startswith((b'import config', b'import plugin')):
+                                    possibly_incompatible = True
                                 fd.write(line)
-                    if newFileName.endswith('__init__.py'):
-                        with open(newFileName) as fd:
-                            lines = list(filter(lambda x:'import plugin' in x,
-                                fd.readlines()))
-                            if lines and lines[0].startswith('from . import'):
-                                # This should be already Python 3-compatible
-                                run_2to3 = False
         finally:
             archive.close()
             del archive
-        if run_2to3:
-            try:
-                import lib2to3
-            except ImportError:
-                return _('Plugin is probably not compatible with your '
-                        'Python version (3.x) and could not be converted '
-                        'because 2to3 is not installed.')
-            import subprocess
-            fixers = []
-            subprocess.Popen(['2to3', '-wn', os.path.join(directory, plugin)]) \
-                    .wait()
-            return _('Plugin was designed for Python 2, but an attempt to '
-                    'convert it to Python 3 has been made. There is no '
-                    'guarantee it will work, though.')
-        else:
+        if possibly_incompatible:
+            return _('Plugin installed. However, it may be incompatible with '
+                     'Python 3 and require manual code changes to work correctly.')
         return _('Plugin successfully installed.')
 
     def getInfo(self, plugin):

plugins/PluginDownloader/test.py

@@ -29,11 +29,9 @@
 ###
 
 import os
-import sys
 import shutil
 
 from supybot.test import *
-import supybot.utils.minisix as minisix
 
 pluginsPath = '%s/test-plugins' % os.getcwd()
 
@@ -80,17 +78,15 @@ class PluginDownloaderTestCase(PluginTestCase):
         self.assertNotError('plugindownloader install Hoaas DuckDuckGo')
         self._testPluginInstalled('DuckDuckGo')
 
+    def testInstallLegacyWarning(self):
+        self.assertRegexp('plugindownloader install frumious Codepoints',
+                          'may be incompatible')
+
     def testInfo(self):
         self.assertResponse('plugindownloader info progval Twitter',
                 'Advanced Twitter plugin for Supybot, with capabilities '
                 'handling, and per-channel user account.')
 
-    if minisix.PY3:
-        def test_2to3(self):
-            self.assertRegexp('plugindownloader install SpiderDave Pastebin',
-                    'convert')
-            self.assertNotError('load Pastebin')
-
 if not network:
     class PluginDownloaderTestCase(PluginTestCase):
         pass