From: Junio C Hamano <gitster@pobox.com>
Date: Thu, 19 Jul 2018 22:38:35 GMT
Subject: Re: Find commit that referenced a blob first
Message-ID: <xmqqr2jydf6c.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <CAGZ79kbJnyRbeH8yMa=QaqNofA_Ek_SwmH5qRaCaq4cyQ26Kqg@mail.gmail.com>

Stefan Beller <sbeller@google.com> writes:

> On Thu, Jul 19, 2018 at 2:02 PM Lars Schneider <larsxschneider@gmail.com> wrote:
>>
>> Hi,
>>
>> I have a blob hash and I would like to know what commit referenced
>> this blob first in a given Git repo.
>
> git describe <blob>
>
> If the given object refers to a blob, it will be described as
> <commit-ish>:<path>,
> such that the blob can be found at <path> in the <commit-ish>, which itself
> describes the first commit in which this blob occurs in a reverse
> revision walk from HEAD.

You walk from the latest to earlier commit (because there by
definition can be is no reverse pointer from older to newer commit),
and see if it has the blob, and stop when you find one.  Wouldn't it
generally find the most recent use, not the earliest use as Lars
seems to want?

>
> Since
> 644eb60bd01 (builtin/describe.c: describe a blob, 2017-11-15)
> (included first in 2.16.0
>
> You're welcome,
> Stefan