Re: [PATCH 1/2] [GSOC] cat-file: fix --batch report changed-type bug

Jeff King [off-list ref] 于2021年6月3日周四 上午4:01写道：

  This assumption was broken by 845de33a5b (cat-file: avoid noop calls
  to sha1_object_info_extended, 2016-05-18). That commit skips the call
  to oid_object_info_extended() entirely when --batch-all-objects is in
  use, and the custom format does not include any placeholders that
  require calling it.

Or when the custom format only include placeholders like %(objectname) or
%(rest), oid_object_info_extended() will not get the type of the object.

  This results in an error when we try to confirm that the type didn't
  change:

    $ git cat-file --batch=batman --batch-all-objects
    batman
    fatal: object 000023961a0c02d6e21dc51ea3484ff71abf1c74 changed type!?

  and also has other subtle effects (e.g., we'd fail to stream a blob,
  since we don't realize it's a blog in the first place).

  We can fix this by flipping the order of the setup. The check for "do
  we need to get the object info" must come _after_ we've decided
  whether we need to look up the type.

-Peff

--
ZheNing Hu