Re: [Feature Request] git blame showing only revisions from git rev-list --first-parent

> On Fri, Sep 11, 2015 at 11:47:30AM +0100, Stephen Connolly wrote:
>
>> A command line option to `git blame HEAD -- path` that instructs that
>> the revisions of blame be the revisions where the change was applied
>> to the current branch not the revision where the change first
>> originated (i.e. limit commits to `git rev-list --first-parent HEAD`)
>>
>> I can get what I want with the following:
>>
>> git rev-list --first-parent HEAD | awk '{print p " " $0}{p=$0}' >
>> tmpfile && git blame -b -S tmpfile HEAD -- path && rm tmpfile
>>
>> But that is a rather ugly command. Could we have something built in to
>> git blame to make this much easier for users?
>
> I agree this would be a useful feature. Though blame takes rev-list
> options, it doesn't use the stock rev-list traversal internally, so it
> has to handle first-parent itself.
>
> I'm not too familiar with the code, but this _seems_ to work for me:
>
> diff --git a/builtin/blame.c b/builtin/blame.c
> index 21321be..2e03d47 100644
> --- a/builtin/blame.c
> +++ b/builtin/blame.c
> @@ -1375,6 +1375,10 @@ static struct commit_list *first_scapegoat(struct rev_info *revs, struct commit
>  static int num_scapegoats(struct rev_info *revs, struct commit *commit)
>  {
>         struct commit_list *l = first_scapegoat(revs, commit);
> +       if (!l)
> +               return 0;
> +       if (revs->first_parent_only)
> +               return 1;
>         return commit_list_count(l);
>  }
>
>
> I suspect it doesn't work at all with `--reverse`. I also have the
> nagging feeling that this could be handled inside revision.c with
> parent-rewriting, but I don't really know.
>
> But "git blame --first-parent <file>" seems to behave sanely in git.git
> with this.
>
> -Peff