From f73a97aba7f6a586bf96ad970294a332109ab558 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>

Date: Sun, 24 Apr 2022 12:54:57 +0200

Subject: [PATCH] py3.11: fix Enum formatting to work with python3.11-a7

Something strange is happening with .__repr__() access in python3.11:

>>> mkosi.backend.ManifestFormat.mro()

[<enum 'ManifestFormat'>, <class 'mkosi.backend.Parseable'>, <enum 'Enum'>, <class 'object'>]

>>> mkosi.backend.ManifestFormat.changelog.__repr__()

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

  File "/usr/lib64/python3.11/enum.py", line 1194, in __repr__

    return "<%s.%s: %s>" % (self.__class__.__name__, self._name_, v_repr(self._value_))

                                                                  ^^^^^^^^^^^^^^^^^^^^

  File "/home/zbyszek/src/mkosi/mkosi/backend.py", line 95, in __repr__

    return cast(str, getattr(self, "name"))

                     ^^^^^^^^^^^^^^^^^^^^^

AttributeError: 'str' object has no attribute 'name'

Enum somehow subverts normal lookup and makes its own __repr__ function be

used, even though Parseable is listed first in MRO. This seems to be related to

PEP 663, which was rejected, and the changes reverted for -a4 [1], but then the revert

was reverted [2].

Let's just sidestep MRO with a method redefinition:

>>> mkosi.backend.ManifestFormat.changelog.__repr__

<bound method ManifestFormat.__repr__ of changelog>

>>> mkosi.backend.ManifestFormat.changelog.__repr__()

'changelog'

This should work on all python versions. If python3.11 returns to previous

semantics before the final release, we can remove the workaround.

[1] commit acf7403f9baea3ae1119fc6b4a3298522188bf96

Author: Ethan Furman <ethan@stoneleaf.us>

Date:   Sat Jan 15 22:41:43 2022 -0800

    bpo-40066:  [Enum] update str() and format() output (GH-30582)

    Undo rejected PEP-663 changes:

    - restore `repr()` to its 3.10 status

    - restore `str()` to its 3.10 status

[2] commit 42a64c03ec5c443f2a5c2ee4284622f5d1f5326c

Author: Victor Stinner <vstinner@python.org>

Date:   Mon Jan 17 13:58:40 2022 +0100

    Revert "bpo-40066:  [Enum] update str() and format() output (GH-30582)" (GH-30632)

    This reverts commit acf7403f9baea3ae1119fc6b4a3298522188bf96.

---

 mkosi/backend.py | 8 ++++++++

 1 file changed, 8 insertions(+)

diff --git a/mkosi/backend.py b/mkosi/backend.py

index 78006f392a..3c57ec6295 100644

--- a/mkosi/backend.py

+++ b/mkosi/backend.py

@@ -217,11 +217,19 @@ class OutputFormat(Parseable, enum.Enum):

     def has_fs_compression(self) -> bool:

         return self.is_squashfs() or self.is_btrfs()

+    def __repr__(self) -> str:

+        return Parseable.__repr__(self)

+    def __str__(self) -> str:

+        return Parseable.__str__(self)

 class ManifestFormat(Parseable, enum.Enum):

     json      = "json"       # the standard manifest in json format

     changelog = "changelog"  # human-readable text file with package changelogs

+    def __repr__(self) -> str:

+        return Parseable.__repr__(self)

+    def __str__(self) -> str:

+        return Parseable.__str__(self)

 class PartitionIdentifier(enum.Enum):

     esp        = 'esp'