> -----Original Messages-----
> From: "Junio C Hamano" <gitster@xxxxxxxxx>
> Sent Time: 2019-10-09 11:02:44 (Wednesday)
> To: wuzhouhui <wuzhouhui14@xxxxxxxxxxxxxxxx>
> Cc: git@xxxxxxxxxxxxxxx, cuifang@xxxxxxxxx
> Subject: Re: How to find the commit that erase a change
>
> wuzhouhui <wuzhouhui14@xxxxxxxxxxxxxxxx> writes:
>
> > I have a file which contains complicated change history. When I use
> > git log -p file
> > to see all changes made in this file, I found that a change disappeared
> > for no reason.
>
> "git log [-p] <pathspec>" is not about seeing *all* changes made to
> the path(s) that match the pathspec. Especially when your history
> has merges, the command is to give you _one_ simplest explanation as
> to how the contents of the path(s) came to be in the shape you see
> in HEAD.
>
> So for example, if you have a history like this (time flows from
> left to right):
>
> O-----A-----B----M-----N
> \ /
> \ /
> X----Y
>
> where A or B did *not* touch "file", X added a definition of func()
> to "file", Y reverted the change X made to "file", M made a natural
> merge between B and Y and N did not touch "file", "git log N file"
> would not even show the existence of commits X or Y. In the larger
> picture, at ancient time O, the file started without func(), and
> none of the commits A, B, M or N felt the need to add it and as the
> result, N does not need the unwanted func(). So "file's contents
> are the same since O throughout the history reaching N" is given as
> _one_ simplest explanation.
>
> The "--full-history" option may help, though.
"--full-history" doesn't resolve my problem, but
git log -p -c file
does. I found that my change was erased in a merge commit.
Thanks.
