Re: Am able to delete a file with no trace in the log

From: Avery Pennarun <apenwarr@gmail.com>
Date: Jun 3, 2009, 21:59 UTC
Message-ID: <32541b130906031459p32640f4dte5e2e079cf4093d7@mail.gmail.com>
In-Reply-To: <alpine.LFD.2.01.0906031431100.4880@localhost.localdomain>

On Wed, Jun 3, 2009 at 5:33 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote:

Show 18 quoted lines

> On Wed, 3 Jun 2009, Junio C Hamano wrote:
>> E.g. "git log --graph --oneline -- git-clone.sh" shows that the scripted
>> version ceased to exist at 8434c2f
>
> Btw, this example misses the whole point of the original problem.
>
> The original problem was:
>
>  - create new file 'x' in branch 'a'
>
>  - merge branch 'a' into branch 'b', but because of a merge conflict and
>   confurion in the merge, the merge result doesn't contain 'x' any more.
>
>  - try to find out what happened to 'x' after-the-fact.
>
> Try it. Git really doesn't make it very easy, because git will notice that
> 'x' didn't exist before the branch either (in branch 'b'), so there will
> be _no_ sign of 'x' actually going away.

Note that full-file deletion is only one particular case of a general problem. Consider this script:

===

#!/bin/bash rm -rf testb mkdir testb cd testb git init echo 'initial a' >a echo 'initial b' >b git add a b git commit -m 'initial commit'

git branch sub

echo 'first a change' >>a git add a git commit -m 'modify a'

git checkout sub echo 'second a change' >>a git add a git commit -m 'modify a differently'

git checkout master git merge -s ours sub

===

"git log -p" will show the addition of the line "second a change" to a, but it doesn't show that, in fact, this line was later deleted because of a botched merge. There is no obvious way to find out in which commit the line was lost. If someone doing a code review is reviewing all the patches from "git log -p", then they'll miss the fact that this patch was lost.

('git log -p -- a" doesn't show that the line was added at all - which is true, in some sense, but it's equally true that, in the example you gave, 'x' was never added.)

Have fun,

Avery