typing: add a cast to `mercurial.patch` to unconfuse pytype 2024.10.11
I've seen this in other, more modern versions of pytype than what we use in CI-
it thinks the return of `get_payload()` is `Message | bytes`, and then complains
about `if not payload.endswith(b'\n')` below, saying `Message` doesn't have that
function. That's correct, but according to the table in `get_payload()` that
documents what the method returns, the only possible values are `bytes | None`
when `decode=True` and the `i` argument isn't passed. And `None` isn't possible
if we trust the `Content-Type` header.
While here, I added a type hint for the `part` variable, since PyCharm couldn't
figure out what was going on here, and that made navigating to the code
impossible.
--- a/mercurial/patch.py Sun Feb 16 01:20:24 2025 +0100
+++ b/mercurial/patch.py Tue Feb 11 21:21:17 2025 -0500
@@ -46,6 +46,8 @@
)
if typing.TYPE_CHECKING:
+ import email
+
from typing import (
Any,
Iterator,
@@ -279,12 +281,18 @@
diffs_seen = 0
ok_types = (b'text/plain', b'text/x-diff', b'text/x-patch')
message = b''
+
+ part: email.message.Message
for part in msg.walk():
content_type = pycompat.bytestr(part.get_content_type())
ui.debug(b'Content-Type: %s\n' % content_type)
if content_type not in ok_types:
continue
- payload = part.get_payload(decode=True)
+
+ # When decode=True, the only possible return types are bytes or None
+ # for a multipart message. But it can't be multipart here, because the
+ # Content-Type was just checked.
+ payload = typing.cast(bytes, part.get_payload(decode=True))
m = diffre.search(payload)
if m:
hgpatch = False