[PATCH v4 0/2] reflog: add format %gb

["Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com>]

Create a better reflog. Follows the discussion in
https://lore.kernel.org/git/akZfm-igZKeHaDST@pks.im/.

The reflog of HEAD records the work done on every branch, so "git reflog"
mixes them and does not say which entry was made on which branch. This adds
a "%gb" placeholder that names the branch HEAD was on when each entry was
recorded:

$ git log -g --format='%h %gd: (%gb) %gs'
9c8d7e6 HEAD@{0}: (topic) rebase (finish): returning to refs/heads/topic
1a2b3c4 HEAD@{2}: (topic) rebase (start): checkout main
1a2b3c4 HEAD@{3}: (main) commit: fix typo


It follows branch switches, branch renames and rebases, including "git
rebase ", rebases of a detached HEAD and rebases of a branch that was
already up to date. When HEAD was detached, the entry shows "detached at ".

Changes in v4:

 * %gb now names the right branch when git rebase <upstream> <branch> runs
   with GIT_REFLOG_ACTION set.
 * Reworded the %gb commit message.

Changes in v3:

 * Dropped --operations.
 * Replaced --historical-branch with a %gb placeholder for --format, e.g.
   git log -g --format='%h %gd: (%gb) %gs'.
 * %gb names the right branch after git rebase <upstream> <branch>, a rebase
   of a detached HEAD and an up-to-date rebase.
 * Named the returning to and checkout reflog strings in reflog.h too.

Changes in v2:

 * Move the "historical branch" rightward in the display for cleaner
   alignment.
 * Improve commit messages.

Harald Nordgren (2):
  reflog: name the strings that mark switches, renames and rebase steps
  pretty: add %gb to name the branch of each reflog entry

 Documentation/pretty-formats.adoc |   3 +
 builtin/branch.c                  |   3 +-
 builtin/checkout.c                |   3 +-
 builtin/rebase.c                  |  19 ++--
 object-name.c                     |   3 +-
 pretty.c                          |   4 +
 reflog-walk.c                     | 167 ++++++++++++++++++++++++++++--
 reflog-walk.h                     |   2 +
 reflog.h                          |   8 ++
 sequencer.c                       |  13 +--
 t/t1414-reflog-walk.sh            | 137 ++++++++++++++++++++++++
 wt-status.c                       |   3 +-
 12 files changed, 340 insertions(+), 25 deletions(-)


base-commit: 750f5de7dfe9a4062f95088212b063f189d50e91
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2448%2FHaraldNordgren%2Freflog-operations-v4
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2448/HaraldNordgren/reflog-operations-v4
Pull-Request: https://github.com/git/git/pull/2448

Range-diff vs v3:

 1:  4d779e8da3 = 1:  f960a24b8b reflog: name the strings that mark switches, renames and rebase steps
 2:  dee548f9b1 ! 2:  99a1047702 pretty: add %gb to name the branch of each reflog entry
     @@ Commit message
              1a2b3c4 HEAD@{3}: (main) commit: fix typo
              5d6e7f8 HEAD@{4}: (main) checkout: moving from topic to main
      
     -    The branch is read from the entries that branch switches, branch
     -    renames and rebases leave behind. The entries of a rebase are named
     -    after the branch being rebased. When HEAD was detached, the entry
     -    shows "detached at <commit>" with the commit HEAD was at when it
     -    moved on. When nothing older in the reflog says which branch a rebase
     -    started on, the rebase is taken to have started on the branch it
     -    rebased. For the reflog of any other ref, "%gb" is the name of that
     -    ref.
     +    The branch is read from the entries created by branch switches,
     +    branch renames and rebases. The entries of a rebase are labeled with
     +    the branch being rebased. When HEAD was detached, the entry shows
     +    "detached at <commit>" with the commit HEAD was at when it moved on.
     +    When nothing older in the reflog says which branch a rebase started
     +    on, the rebase is taken to have started on the branch it rebased. For
     +    the reflog of any other ref, "%gb" is the name of that ref.
      
          Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
      
     @@ reflog-walk.c: static void complete_reflogs_clear(void *util, const char *str UN
      +	return p;
      +}
      +
     ++static const char *skip_rebase_checkout(const char *message)
     ++{
     ++	const char *p = strstr(message, " (");
     ++	const char *colon = strstr(message, ": ");
     ++
     ++	if (!colon || (p && p < colon) ||
     ++	    !skip_prefix(colon + 2, REFLOG_CHECKOUT, &p))
     ++		return NULL;
     ++	return p;
     ++}
     ++
      +struct branch_move {
      +	const char *from, *to;
      +	size_t from_len, to_len;
     @@ reflog-walk.c: static void complete_reflogs_clear(void *util, const char *str UN
      +		   skip_prefix(to, REFLOG_RETURNING_TO, &to)) {
      +		move->from = move->to = to;
      +		move->from_len = strcspn(to, "\n");
     -+	} else if (skip_prefix(message, "rebase: " REFLOG_CHECKOUT, &to)) {
     ++	} else if ((to = skip_rebase_checkout(message))) {
      +		move->to = to;
      +	} else if (!skip_rebase_step(message, REFLOG_STEP_START)) {
      +		return false;
     @@ t/t1414-reflog-walk.sh: test_expect_success 'walk prefers reflog to ref tip' '
      +	)
      +'
      +
     ++test_expect_success '%gb follows "git rebase <upstream> <branch>" with GIT_REFLOG_ACTION' '
     ++	(
     ++		cd branches &&
     ++		git switch main &&
     ++		GIT_REFLOG_ACTION="sync switch" git rebase main topic &&
     ++
     ++		cat >expect <<-\EOF &&
     ++		(topic) sync switch: checkout topic
     ++		(main) checkout: moving from topic to main
     ++		EOF
     ++		git log -g -2 --format="(%gb) %gs" >actual &&
     ++		test_cmp expect actual
     ++	)
     ++'
     ++
      +test_expect_success '%gb names a detached HEAD by the commit it was left at' '
      +	(
      +		cd branches &&

-- 
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