On Wed, Apr 21, 2021 at 8:39 AM Ævar Arnfjörð Bjarmason
<avarab@xxxxxxxxx> wrote:
> > In reftable, there is no notion of a per-ref 'existence' of a reflog. Each
> > reflog entry has its own key, so it is not possible to distinguish between
> > {reflog doesn't exist,reflog exists but is empty}. This makes the logic
> > in log_ref_setup() (file refs/files-backend.c), which depends on the existence
> > of the reflog file infeasible.
>
> Okey, so I'd follow this if the test was doing something like "test -e
> .git/logs" to test whether we didn't have reflogs for a specific branch
> or something....
>
..
> In your v7[1] of the reftable series there's no patch to
> Documentation/revisions.txt altering that blurb.
>
> So it seems to me that between this & that series there's some closing
> of the gap needed with how this "must have an existing log" even works
> under reftable.
the problem is that it's using BRANCH@{0} as a way to indicate whether
the reflog exists or not, and something looks at the current tip of
BRANCH for @{0} even if the reflog is empty:
hanwen@hanwen1:~/vc/git$ ls -l .git/logs/refs/heads/windows-2
-rw-r----- 1 hanwen primarygroup 0 Apr 29 20:08 .git/logs/refs/heads/windows-2
hanwen@hanwen1:~/vc/git$ git rev-parse windows-2@{0}
7048e02d79350e332f34f2bfae50eb28700cbeda
hanwen@hanwen1:~/vc/git$ rm .git/logs/refs/heads/windows-2
hanwen@hanwen1:~/vc/git$ git rev-parse windows-2@{0}
windows-2@{0}
fatal: ambiguous argument 'windows-2@{0}': unknown revision or path
not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
in reftable, with the current implementation, all reflogs are assumed
to exist (but possibly empty).
> Per [2] I had assumed that this worked under reftable by abstracting
> away the syntax to some query for the ref name, and faking up "file does
> not exist" as "there were no records" to anything like rev-parse, but it
> doesn't work like that?
you could make it work like that, but I bet that then there are a host
of other tests that fail because they might check that a reflog exists
(but is empty) after doing eg. "git reflog expire --all".
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