Well that was interesting, but --first-parent does not do what you'd expect
on git blame.

I was able to construct a command sequence to do what I want though:

git rev-list --first-parent HEAD | awk '{print p " " $0}{p=$0}' >
tmpfile && git blame -b -S tmpfile HEAD -- path && rm tmpfile


On Thu, 10 Sep 2015 at 21:20 Philip Oakley <philipoak...@iee.org> wrote:

> ----- Original Message -----
> *From:* Philip Oakley <philipoak...@iee.org>
> *To:* git-users@googlegroups.com
> *Sent:* Thursday, September 10, 2015 8:48 AM
> *Subject:* Re: [git-users] Treat merges as squashed commits in git
> log/git blame/gitk etc
>
> ----- Original Message -----
>
> *From:* Stephen Connolly <stephen.alan.conno...@gmail.com>
> *To:* Git for human beings <git-users@googlegroups.com>
> *Sent:* Wednesday, September 09, 2015 9:56 AM
> *Subject:* [git-users] Treat merges as squashed commits in git log/git
> blame/gitk etc
>
> Hi,
>
> At my work and on some of the open source communities that I contribute
> to, there is a healthy debate about how to handle merge commits. I can
> break this into two camps:
>
> * People who think that when you are merging a change from a pull request,
> you should squash all commits immediately prior to the merge as this means
> you can see all the changes associated with the merge in the same commit
> and simplifies history browsing.
>
> * People who think that when you are merging a change from a pull request,
> you should never squash commits and just merge them all so that you have
> access to the history of development of that feature.
>
> I tend to lean towards the second camp myself, but I recognise that the
> first camp has a point... namely when you are using tooling such as `git
> log`, `git blame` and `gitk` I cannot seem to supply an option that says
> "Hey when you see a merge commit, treat it as if all commits from the 2nd
> and subsequent parents of the merge were squashed"
>
> With such an option, people in the first camp could use that option choose
> to see a "linear" history with all merge commits appearing as if they were
> squashed commits, git blame could help them identify when the actual
> "feature" was merged rather than having to trace back up the history lines
> from the commit where the line was touched to find the line.
>
> By way of example (and I could have searched a bit harder for a more
> tricky example):
>
> Let's take this line here:
> https://github.com/stephenc/jenkins/blame/d331c12bbc2cf863efd39e0b135c584da364937a/core/src/main/java/hudson/model/Computer.java#L1003
>
> Now that line was last changed in 6f343dc7c2f0c32e9eb1a0b5d588a2e7ad6f62ba
> and GitHub (as well as `git blame` will correctly show the change as
> resulting from that commit)
>
> However the master branch was only modified
> in 71e684ad900363c48d845f73c1993f90de4417ad
>
> So with the command line option I would like to see you would have `git
> blame --squash-merges` report line 1003 as changed
> in 71e684ad900363c48d845f73c1993f90de4417ad not
> 6f343dc7c2f0c32e9eb1a0b5d588a2e7ad6f62ba
>
> Similarly, `git log --squash-merges` would show
> 71e684ad900363c48d845f73c1993f90de4417ad in the log but omit all the
> commits merged in with that...
>
> Now how close can I get with the existing options:
>
> * I think that `git log --first-parent` is almost what I want,
>
>
> <https://lh3.googleusercontent.com/-fFiYb4_neb0/Ve_y_DdvNvI/AAAAAAAAAb4/2Ojvccwo2Fg/s1600/Screen%2BShot%2B2015-09-09%2Bat%2B09.50.01.png>
>
> * `gitk --first-parent` has the distraction of showing that the merge
> commits were a merge by having those merge-into lines
>
>
> <https://lh3.googleusercontent.com/-Y7lccFN6Mzg/Ve_zLssSpcI/AAAAAAAAAcA/0MXSmMCLjc8/s1600/Screen%2BShot%2B2015-09-09%2Bat%2B09.47.53.png>
>
> I can probably live with that distraction, but when you get to the commit
> line itself drifting... it seems to be distracting me again, e.g.
>
>
> <https://lh3.googleusercontent.com/-NcIFRSYO_HA/Ve_zbZgs-KI/AAAAAAAAAcI/1dTKIcZbDYc/s1600/Screen%2BShot%2B2015-09-09%2Bat%2B09.50.21.png>
>
> * `git blame` doesn't have a `--first-parent` option
>
>
> So I guess my questions:
>
>
> * Am I correct in my interpretation of --first-parent? Is it doing what I
> want or am I just being accidentally lucky for the cases I have inspected
>
> * (assuming that --first-parent is what I want) How do I submit a feature
> request for `git blame --first-parent`?
>
>
> Thanks in advance,
>
>
> -Stephen
>
>
> There's been a recent discusion about this on the main git list recently
> http://news.gmane.org/gmane.comp.version-control.git.
> http://thread.gmane.org/gmane.comp.version-control.git/277536/focus=277539
>
> Merges are not shown by default, but the -m option will show them. The
> default is based on historical use rather than the many varied current
> usage style.
>
> The --firstparent is the one for triming off the side branches, but
> without the -m you don't get the merges!, which misses the critical merge
> message (you do write good merge messages don't you ;-)
>
> Don't forget that gitk and git gui are separately coded (tcl) and
> maintained from the git.git tool set.
>
> In general I'd say it (both showing merges, and the blame discussion) was
> something worth discussing upstream on the git mailing list
> g...@vger.kernel.org <g...@vger.kernel.org>
> --
> Philip
> [just another user]
>
> Some extra stuff:
>
> The man page has hidden secrets (as is common)..
>
> In particular the –S option mentions that one can provide a revs file, 
> “instead
> of calling git-rev-list(1).”!
>
> If one looks at the source code, and the usage string (git blame –h)
>
> https://github.com/git/git/blob/master/builtin/blame.c#L32
>
>
>
> static char blame_usage[] = N_("git blame [<options>] [<rev-opts>] [<rev>]
> [--] <file>");
>
>
>
> static const char *blame_opt_usage[] = {
>
>                 blame_usage,
>
>                 "",
>
>                 N_("<rev-opts> are documented in git-rev-list(1)"),
>
>                 NULL
>
> };
>
>
>
> You can see that you can use many of the git-rev-list options, which drops
> you into a whole new world (take a rope; well secured.. ;-)
>
> Thus you can use --firstparent, etc.
>
>
>
> It definitely looks like the man pages could do with some TLC from a real
> user, rather than from the devs who already know the answer. (i.e. a
> contribution to patch the documentation would be something worth putting
> forward!)
>
>
>
> It may be that your suggested blame options are still required to be added
> to git.git.
>
> And then the gitk and git gui can separately be updated to allow their use.
>

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