Re: [PATCH v2 2/2] Doc/check-ref-format: clarify information about @{-N} syntax

[Junio C Hamano <gitster@pobox.com>]

Kaartic Sivaraam <kaartic.sivaraam@gmail.com> writes:

>> Stepping back a bit, the mild suspicion above says
>> 
>>     $ git checkout HEAD^0
>>     ... do things ...
>>     $ git checkout -b temp
>>     ... do more things ...
>>     $ git checkout -B @{-1}
>> 
>> that creates a new branch whose name is 40-hex of a commit that
>> happens to be where we started the whole dance *is* a bug.  No sane
>> user expects that to happen, and the last step "checkout -B @{-1}"
>> should result in an error instead [*1*].
>> 
>> I was wondering if "git check-ref-format --branch @{-1}", when used
>> in place of "checkout -B @{-1}" in the above sequence,
>
> I guess you mean '... "git checkout -B $(git check-ref-format --branch
> @{-1}", when used in place of "git checkout -B @{-1}" ...' ?

No you guessed wrong.  I was (and am) wondering if the last step in
the following sequence should fail.

>>     $ git checkout HEAD^0
>>     ... do things ...
>>     $ git checkout -b temp
>>     ... do more things ...
>>     $ git check-ref-format --branch @{-1}

And I am leaning towards saying that it is a bug that it does not
fail; @{-1} is a detached HEAD and not a concrete branch name in
this case, so "check-ref-format --branch" should at least notice
and say that it is a request that may lead to a nonsense next step
(which is to create a branch with that 40-hex name).