<stefan.naewe@xxxxxxxxxxxxxxxxxxxx> writes:
> Let's see:
> $ git rev-parse --verify --quiet master@{xyz} || echo No
> No
>
> $ git rev-parse --verify --quiet master@{u} || echo No
> fatal: no upstream configured for branch 'master'
> No
Yup, that is unfortunate. The above two pass different codepaths in
sha1_name.c::get_sha1_basic().
* The code first notices "master@{anything}" has @{anything}
suffix, which could be @{123} (counted reflog), @{1.hour.ago}
(timed reflog), @{-1} (prior checkout---valid only when nothing
comes before "@{...}") or @{upstream}/@{push}.
* The first two goes through dwim_log(), together with
'master@{xyz}' to locate the reflog of 'master' (i.e. what comes
before that @{anything}) and identifies that we need to look at
the log for 'refs/heads/master', looks up an appropriate entry,
and the processing ends there, returning success. However, 'xyz'
is not a valid specification for either counted or timed reflog,
so the function returns failure for 'master@{xyz}', letting the
remainder of the callchain to take care of it.
* The third one goes to interpret_nth_prior_checkout() and the
processing ends there, returning success.
* The last one goes to dwim_ref(), together with just 'master'
without any @{anything}. It tries to turn master@{upstream} or
master@{push} to refs/remotes/origin/master and then it is used
to grab the object name pointed by it.
The helper function dwim_ref() calls to turn master@{upstream} to
refs/remotes/origin/master, interpret_branch_name(), is designed to
die() when fed a ref without upstream (or @{push} when there is no
such thing).
Naively, one would imagine that the die() can be demoted to an
internal error return to the caller (just like 'master@{xyz}' is
rejected silently in the dwim_log() codepath) and everything else
should go well. It is unfortunately not sufficient, though, as the
other callers to interpret_branch_name() rely on the function to
die and are not prepared to show the error messages themselves.
So I think this is fixable and the right approach to fix it is as
hinted above, i.e.
* audit callers of interpret_branch_name() and find the ones that
depend on the function to die (i.e. it does not handle the case
where interpret_branch_name() notices that 'master@{upstream}'
does not exist). Change them to die with an appropriate message
themselves.
* change interpret_branch_mark(), which is actually where the die()
happens, so that it can notice a request to use 'master@{upstream}'
when there is no such upstream and signal an error to the caller.
I am not saying that you should be the one to fix it, though ;-) The
above is to help those who may be interested to look into the codepath
to do so.
Thanks.
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