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From: Jeff King <peff@peff.net>
To: Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, me@ttaylorr.com,
	Derrick Stolee <dstolee@microsoft.com>
Subject: Re: [PATCH] revision: --include-diversions adds helpful merges
Date: Wed, 8 Apr 2020 14:48:43 -0400	[thread overview]
Message-ID: <20200408184843.GA1963695@coredump.intra.peff.net> (raw)
In-Reply-To: <pull.599.git.1586308923544.gitgitgadget@gmail.com>

On Wed, Apr 08, 2020 at 01:22:03AM +0000, Derrick Stolee via GitGitGadget wrote:

> The default file history simplification of "git log -- <path>" or
> "git rev-list -- <path>" focuses on providing the smallest set of
> commits that first contributed a change. The revision walk greatly
> restricts the set of walked commits by visiting only the first
> TREESAME parent of a merge commit, when one exists. This means
> that portions of the commit-graph are not walked, which can be a
> performance benefit, but can also "hide" commits that added changes
> but were ignored by a merge resolution.
> [...]

Thanks for a really great description of the problem.

Playing around with the patch, I found one curiosity. Try this:

  git log --graph --oneline origin -- GIT-VERSION-GEN >old
  git log --graph --oneline --include-diversions \
                            origin -- GIT-VERSION-GEN >new
  diff -u old new

The first hunk has:

  @@ -70,6 +70,7 @@
   * 20769079d2 Git 2.12-rc2
   * 5588dbffbd Git 2.12-rc1
   * 6e3a7b3398 Git 2.12-rc0
  +* 0a45050a14 Merge branch 'rj/git-version-gen-do-not-force-abbrev'
   * a7659747c2 GIT-VERSION-GEN: do not force abbreviation length used by 'describe'
   * 8d7a455ed5 Start post 2.11 cycle
   * 454cb6bd52 Git 2.11

which makes sense. That merge brought in a7659747c2, and the other side
hadn't touched it. But I can't tell from the output how the two are
related. Nor can I just add "-p" to the invocation; after we've
simplified, it has only a single parent, but it's TREESAME to that
parent. So it has no diff.

I actually think the most descriptive output here would be something
like:

  * 6e3a7b3398 Git 2.12-rc0
  * 0a45050a14 Merge branch 'rj/git-version-gen-do-not-force-abbrev'
  |\
  | * a7659747c2 GIT-VERSION-GEN: do not force abbreviation length used by 'describe'
  |/
  * Start post 2.11 cycle

I.e., leaving both parents intact for a "diversion" merge. But maybe
that would have secondary effects in other places.

-Peff

  parent reply	other threads:[~2020-04-08 18:48 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-08  1:22 Derrick Stolee via GitGitGadget
2020-04-08  1:30 ` Junio C Hamano
2020-04-08  1:39   ` Derrick Stolee
2020-04-08 15:28     ` Derrick Stolee
2020-04-08 19:46       ` Junio C Hamano
2020-04-08 20:05         ` Jeff King
2020-04-08 20:22           ` Derrick Stolee
2020-04-08 21:35             ` Junio C Hamano
2020-04-08 23:59               ` Derrick Stolee
2020-04-09  0:08                 ` Junio C Hamano
2020-04-09 11:52                   ` Derrick Stolee
2020-04-09 14:28                   ` Philip Oakley
2020-04-09 15:56                     ` Junio C Hamano
2020-04-09 17:20                       ` Derrick Stolee
2020-04-09 18:24                         ` Jeff King
2020-04-09 18:55                           ` Junio C Hamano
2020-04-09 19:21                             ` Jeff King
2020-04-08  2:13 ` brian m. carlson
2020-04-08 18:48 ` Jeff King [this message]
2020-04-09  0:01 ` [PATCH v2] " Derrick Stolee via GitGitGadget
2020-04-10 12:19   ` [PATCH v3] revision: --show-pulls " Derrick Stolee via GitGitGadget
2020-04-10 20:06     ` Junio C Hamano
2020-04-10 21:43       ` Derrick Stolee

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