Merge lp:~jameinel/bzr/pyrex_099_bug_582656 into lp:bzr/2.0

[John A Meinel]

Work around a bug (#582656) in how Pyrex handles catching exceptions.

This is a workaround for pyrex bug #582656. Basically, new versions of pyrex broke code that catches an exception but doesn't assign it to an object. Stuff like:

...
 except Exception:
  do_stuff

It seems to be leaving the trapped exception on the stack (PyErr_Occurred() == True). Which means that if 'do_stuff()' calls a function with indeterminate exception state, it can cause the exception to get raised.

In the bug, we were doing:

 except KeyError:
   ...
   if x == y:
   ...

And PyObject_Cmp() seems to have a side-effect exception check.

Anyway, the workaround is to just change all of those exception catches to assigning it to a variable, such as:

 except Exception, _:

_dirstate_helpers_pyx.pyx seems to be the only extension that suffers from this (as checked by:
 grep -rnI "^\s.*except[^,]:").

I've also sent a bug report to the pyrex mailing list (since I don't think they have a real bug tracker.)

I'm proposing this for 2.0 and expecting it to propagate up.

[Robert Collins (lifeless)]

Doit.

review: Approve

=== modified file 'bzrlib/_dirstate_helpers_pyx.pyx'
--- bzrlib/_dirstate_helpers_pyx.pyx	2010-01-05 04:59:57 +0000
+++ bzrlib/_dirstate_helpers_pyx.pyx	2010-05-19 17:12:31 +0000
@@ -1,4 +1,4 @@
-# Copyright (C) 2007, 2008 Canonical Ltd
+# Copyright (C) 2007-2010 Canonical Ltd
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -1219,7 +1219,7 @@
             else:
                 try:
                     source_parent_id = self.old_dirname_to_file_id[old_dirname]
-                except KeyError:
+                except KeyError, _:
                     source_parent_entry = self.state._get_entry(self.source_index,
                                                            path_utf8=old_dirname)
                     source_parent_id = source_parent_entry[0][2]
@@ -1236,7 +1236,7 @@
             else:
                 try:
                     target_parent_id = self.new_dirname_to_file_id[new_dirname]
-                except KeyError:
+                except KeyError, _:
                     # TODO: We don't always need to do the lookup, because the
                     #       parent entry will be the same as the source entry.
                     target_parent_entry = self.state._get_entry(self.target_index,
@@ -1478,7 +1478,7 @@
             # interface doesn't require it.
             try:
                 self.current_root = self.search_specific_files.pop()
-            except KeyError:
+            except KeyError, _:
                 raise StopIteration()
             self.searched_specific_files.add(self.current_root)
             # process the entries for this containing directory: the rest will be
@@ -1567,7 +1567,7 @@
                         #            and e.winerror == ERROR_DIRECTORY
                         try:
                             e_winerror = e.winerror
-                        except AttributeError:
+                        except AttributeError, _:
                             e_winerror = None
                         win_errors = (ERROR_DIRECTORY, ERROR_PATH_NOT_FOUND)
                         if (e.errno in win_errors or e_winerror in win_errors):
@@ -1656,7 +1656,7 @@
                     try:
                         self.current_dir_info = self.dir_iterator.next()
                         self.current_dir_list = self.current_dir_info[1]
-                    except StopIteration:
+                    except StopIteration, _:
                         self.current_dir_info = None
                 else: #(dircmp > 0)
                     # We have a dirblock entry for this location, but there
@@ -1803,7 +1803,7 @@
                                 and stat.S_IEXEC & current_path_info[3].st_mode)
                             try:
                                 relpath_unicode = self.utf8_decode(current_path_info[0])[0]
-                            except UnicodeDecodeError:
+                            except UnicodeDecodeError, _:
                                 raise errors.BadFilenameEncoding(
                                     current_path_info[0], osutils._fs_enc)
                             if changed is not None:
@@ -1851,7 +1851,7 @@
                 try:
                     self.current_dir_info = self.dir_iterator.next()
                     self.current_dir_list = self.current_dir_info[1]
-                except StopIteration:
+                except StopIteration, _:
                     self.current_dir_info = None
 
     cdef object _next_consistent_entries(self):