If a rebase is started with a --strategy option other than "ort" or
"recursive" then "merge -c" does not allow the user to reword the
commit message.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If the user runs git log while rewording a commit it is confusing if
sometimes we're amending the commit that's being reworded and at other
times we're creating a new commit depending on whether we could
fast-forward or not[1]. For this reason the reword command ensures
that there are no uncommitted changes when rewording. The reword
command also allows the user to edit the todo list while the rebase is
paused. As 'merge -c' also rewords commits make it behave like reword
and add a test.
[1] https://lore.kernel.org/git/xmqqlfvu4be3.fsf@gitster-ct.c.googlers.com/T/#m133009cb91cf0917bcf667300f061178be56680a
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Carefully excluding t3404, which sees independent development elsewhere
at the time of writing, we use `main` as the default branch name in
t34*. This trick was performed via
$ (cd t &&
sed -i -e 's/master/main/g' -e 's/MASTER/MAIN/g' \
-e 's/Master/Main/g' -- t34*.sh &&
git checkout HEAD -- t34\*)
This allows us to define `GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main`
for those tests.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In addition to the manual adjustment to let the `linux-gcc` CI job run
the test suite with `master` and then with `main`, this patch makes sure
that GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME is set in all test scripts
that currently rely on the initial branch name being `master by default.
To determine which test scripts to mark up, the first step was to
force-set the default branch name to `master` in
- all test scripts that contain the keyword `master`,
- t4211, which expects `t/t4211/history.export` with a hard-coded ref to
initialize the default branch,
- t5560 because it sources `t/t556x_common` which uses `master`,
- t8002 and t8012 because both source `t/annotate-tests.sh` which also
uses `master`)
This trick was performed by this command:
$ sed -i '/^ *\. \.\/\(test-lib\|lib-\(bash\|cvs\|git-svn\)\|gitweb-lib\)\.sh$/i\
GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master\
export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME\
' $(git grep -l master t/t[0-9]*.sh) \
t/t4211*.sh t/t5560*.sh t/t8002*.sh t/t8012*.sh
After that, careful, manual inspection revealed that some of the test
scripts containing the needle `master` do not actually rely on a
specific default branch name: either they mention `master` only in a
comment, or they initialize that branch specificially, or they do not
actually refer to the current default branch. Therefore, the
aforementioned modification was undone in those test scripts thusly:
$ git checkout HEAD -- \
t/t0027-auto-crlf.sh t/t0060-path-utils.sh \
t/t1011-read-tree-sparse-checkout.sh \
t/t1305-config-include.sh t/t1309-early-config.sh \
t/t1402-check-ref-format.sh t/t1450-fsck.sh \
t/t2024-checkout-dwim.sh \
t/t2106-update-index-assume-unchanged.sh \
t/t3040-subprojects-basic.sh t/t3301-notes.sh \
t/t3308-notes-merge.sh t/t3423-rebase-reword.sh \
t/t3436-rebase-more-options.sh \
t/t4015-diff-whitespace.sh t/t4257-am-interactive.sh \
t/t5323-pack-redundant.sh t/t5401-update-hooks.sh \
t/t5511-refspec.sh t/t5526-fetch-submodules.sh \
t/t5529-push-errors.sh t/t5530-upload-pack-error.sh \
t/t5548-push-porcelain.sh \
t/t5552-skipping-fetch-negotiator.sh \
t/t5572-pull-submodule.sh t/t5608-clone-2gb.sh \
t/t5614-clone-submodules-shallow.sh \
t/t7508-status.sh t/t7606-merge-custom.sh \
t/t9302-fast-import-unpack-limit.sh
We excluded one set of test scripts in these commands, though: the range
of `git p4` tests. The reason? `git p4` stores the (foreign) remote
branch in the branch called `p4/master`, which is obviously not the
default branch. Manual analysis revealed that only five of these tests
actually require a specific default branch name to pass; They were
modified thusly:
$ sed -i '/^ *\. \.\/lib-git-p4\.sh$/i\
GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master\
export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME\
' t/t980[0167]*.sh t/t9811*.sh
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The autosquash-and-exec test used "git diff HEAD^!" to mean
"git diff HEAD^ HEAD". Use these directly instead of relying
on the undefined but actual-current behavior of "HEAD^!".
Signed-off-by: Chris Torek <chris.torek@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Log graph comparision logic is duplicated many times in:
- t3430-rebase-merges.sh
- t4202-log.sh
- t4214-log-graph-octopus.sh
- t4215-log-skewed-merges.sh
Consolidate the core of the comparision and sanitization logic in
lib-log-graph, and use it to replace the existing tests.
While at it, lose the singular/plural transition magic from the
sanitize_output helper, which was necessary around 7f814632 ("Use
correct grammar in diffstat summary line", 2012-02-01), that has
long outlived its usefulness.
Signed-off-by: Abhishek Kumar <abhishekkumar8222@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Test cleanup.
* dl/t5520-cleanup:
t5520: replace `! git` with `test_must_fail git`
t5520: remove redundant lines in test cases
t5520: replace $(cat ...) comparison with test_cmp
t5520: don't put git in upstream of pipe
t5520: test single-line files by git with test_cmp
t5520: use test_cmp_rev where possible
t5520: replace test -{n,z} with test-lib functions
t5520: use test_line_count where possible
t5520: remove spaces after redirect operator
t5520: replace test -f with test-lib functions
t5520: let sed open its own input
t5520: use sq for test case names
t5520: improve test style
t: teach test_cmp_rev to accept ! for not-equals
t0000: test multiple local assignment
The logic to avoid duplicate label names generated by "git rebase
--rebase-merges" forgot that the machinery itself uses "onto" as a
label name, which must be avoided by auto-generated labels, which
has been corrected.
* dd/rebase-merge-reserves-onto-label:
sequencer: handle rebase-merges for "onto" message
A label used in the todo list that are generated by "git rebase
--rebase-merges" is used as a part of a refname; the logic to come
up with the label has been tightened to avoid names that cannot be
used as such.
* js/rebase-r-safer-label:
rebase -r: let `label` generate safer labels
rebase-merges: move labels' whitespace mangling into `label_oid()`
In the case where we are using test_cmp_rev() to report not-equals, we
write `! test_cmp_rev`. However, since test_cmp_rev() contains
r1=$(git rev-parse --verify "$1") &&
r2=$(git rev-parse --verify "$2") &&
`! test_cmp_rev` will succeed if any of the rev-parses fail. This
behavior is not desired. We want the rev-parses to _always_ be
successful.
Rewrite test_cmp_rev() to optionally accept "!" as the first argument to
do a not-equals comparison. Rewrite `! test_cmp_rev` to `test_cmp_rev !`
in all tests to take advantage of this new functionality.
Also, rewrite the rev-parse logic to end with a `|| return 1` instead of
&&-chaining into the rev-comparison logic. This makes it obvious to
future readers that we explicitly intend on returning early if either of
the rev-parses fail.
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In order to work correctly, git-rebase --rebase-merges needs to make
initial todo list with unique labels.
Those unique labels is being handled by employing a hashmap and
appending an unique number if any duplicate is found.
But, we forget that beside those labels for side branches,
we also have a special label `onto' for our so-called new-base.
In a special case that any of those labels for side branches named
`onto', git will run into trouble.
Correct it.
Signed-off-by: Doan Tran Cong Danh <congdanhqx@gmail.com>
Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `label` todo command in interactive rebases creates temporary refs
in the `refs/rewritten/` namespace. These refs are stored as loose refs,
i.e. as files in `.git/refs/rewritten/`, therefore they have to conform
with file name limitations on the current filesystem in addition to the
accepted ref format.
This poses a problem in particular on NTFS/FAT, where e.g. the colon,
double-quote and pipe characters are disallowed as part of a file name.
Let's safeguard against this by replacing not only white-space
characters by dashes, but all non-alpha-numeric ones.
However, we exempt non-ASCII UTF-8 characters from that, as it should be
quite possible to reflect branch names such as `↯↯↯` in refs/file names.
Signed-off-by: Matthew Rogers <mattr94@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When a graph contains edges that are in the process of collapsing to the
left, but those edges cross a commit line, the effect is that the edges
have a jagged appearance:
*
|\
| *
| \
*-. \
|\ \ \
| | * |
| * | |
| |/ /
* | |
|/ /
* |
|/
*
We already takes steps to smooth edges like this when they're expanding;
when an edge appears to the right of a merge commit marker on a
GRAPH_COMMIT line immediately following a GRAPH_POST_MERGE line, we
render it as a `\`:
* \
|\ \
| * \
| |\ \
We can make a similar improvement to collapsing edges, making them
easier to follow and giving the overall graph a feeling of increased
symmetry:
*
|\
| *
| \
*-. \
|\ \ \
| | * |
| * | |
| |/ /
* / /
|/ /
* /
|/
*
To do this, we introduce a new special case for edges on GRAPH_COMMIT
lines that immediately follow a GRAPH_COLLAPSING line. By retaining a
copy of the `mapping` array used to render the GRAPH_COLLAPSING line in
the `old_mapping` array, we can determine that an edge is collapsing
through the GRAPH_COMMIT line and should be smoothed.
Signed-off-by: James Coglan <jcoglan@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git rebase --rebase-merges" learned to drive different merge
strategies and pass strategy specific options to them.
* js/rebase-r-strategy:
t3427: accelerate this test by using fast-export and fast-import
rebase -r: do not (re-)generate root commits with `--root` *and* `--onto`
t3418: test `rebase -r` with merge strategies
t/lib-rebase: prepare for testing `git rebase --rebase-merges`
rebase -r: support merge strategies other than `recursive`
t3427: fix another incorrect assumption
t3427: accommodate for the `rebase --merge` backend having been replaced
t3427: fix erroneous assumption
t3427: condense the unnecessarily repetitive test cases into three
t3427: move the `filter-branch` invocation into the `setup` case
t3427: simplify the `setup` test case significantly
t3427: add a clarifying comment
rebase: fold git-rebase--common into the -p backend
sequencer: the `am` and `rebase--interactive` scripts are gone
.gitignore: there is no longer a built-in `git-rebase--interactive`
t3400: stop referring to the scripted rebase
Drop unused git-rebase--am.sh
In many test scripts, there are bespoke definitions of the single quote
that are some variation of this:
SQ="'"
Define a common $SQ variable in test-lib.sh and replace all usages of
these bespoke variables with the common one.
This change was done by running `git grep =\"\'\" t/` and
`git grep =\\\\\'` and manually changing the resulting definitions and
corresponding usages.
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Compute the object IDs used in the todo list instead of hard-coding
them.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We already support merge strategies in the sequencer, but only for
`pick` commands.
With this commit, we now also support them in `merge` commands. The
approach is simple: if any merge strategy option is specified, or if any
merge strategy other than `recursive` is specified, we simply spawn the
`git merge` command. Otherwise, we handle the merge in-process just as
before.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git rebase --abort" used to leave refs/rewritten/ when concluding
"git rebase -r", which has been corrected.
* pw/rebase-abort-clean-rewritten:
rebase --abort/--quit: cleanup refs/rewritten
sequencer: return errors from sequencer_remove_state()
rebase: warn if state directory cannot be removed
rebase: fix a memory leak
If a merge can be fast-forwarded then make sure that we still edit the
commit message if the user specifies -c. The implementation follows the
same pattern that is used for ordinary rewords that are fast-forwarded.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When `rebase -r` finishes it removes any refs under refs/rewritten that
it has created. However if the user aborts or quits the rebase refs are
not removed. This can cause problems for future rebases. For example I
recently wanted to merge a updated version of a topic branch into an
integration branch so ran `rebase -ir` and removed the picks and label
for the topic branch from the todo list so that
merge -C <old-merge> topic
would pick up the new version of topic. Unfortunately
refs/rewritten/topic already existed from a previous rebase that had
been aborted so the rebase just used the old topic, not the new one.
The logic for the non-interactive quit case is changed to ensure
`buf` is always freed.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In quite a few test cases, we were sloppy and used the abbreviation
`--force`, but we really should be precise in what we want to test.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If GIT_SEQUENCE_EDITOR is set then rebase runs it when executing
implicit interactive rebases which are supposed to appear
non-interactive to the user. Fix this by setting GIT_SEQUENCE_EDITOR=:
rather than GIT_EDITOR=:. A couple of tests relied on the old behavior
so they are updated to work with the new regime.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we detect that a `merge` can be skipped because the merged commit
is already an ancestor of HEAD, we do not need to commit, therefore
writing the MERGE_HEAD file is useless.
It is actually worse than useless: a subsequent `git commit` will pick
it up and think that we want to merge that commit, still.
To avoid that, move the code that writes the MERGE_HEAD file to a
location where we already know that the `merge` cannot be skipped.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When calling `merge` on a branch that has already been merged, that
`merge` is skipped quietly, but currently a MERGE_HEAD file is being
left behind and will then be grabbed by the next `pick` (that did
not want to create a *merge* commit).
Demonstrate this.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git rebase -i", when a 'merge <branch>' insn in its todo list
fails, segfaulted, which has been (minimally) corrected.
* pw/rebase-i-merge-segv-fix:
rebase -i: fix SIGSEGV when 'merge <branch>' fails
t3430: add conflicting commit
If a merge command in the todo list specifies just a branch to merge
with no -C/-c argument then item->commit is NULL. This means that if
there are merge conflicts error_with_patch() is passed a NULL commit
which causes a segmentation fault when make_patch() tries to look it up.
This commit implements a minimal fix which fixes the crash and allows
the user to successfully commit a conflict resolution with 'git rebase
--continue'. It does not write .git/rebase-merge/patch,
.git/rebase-merge/stopped-sha or update REBASE_HEAD. To sensibly get the
hashes of the merge parents would require refactoring do_merge() to
extract the code that parses the merge parents into a separate function
which error_with_patch() could then use to write the parents into the
stopped-sha file. To create meaningful output make_patch() and 'git
rebase --show-current-patch' would also need to be modified to diff the
merge parent and merge base in this case.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Move the creation of conflicting-G from a test to the setup so that it
can be used in subsequent tests without creating the kind of implicit
dependencies that plague t3404. While we're at it simplify the
arguments to the test_commit() call the creates the conflicting commit.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The idea of `--exec` is to append an `exec` call after each `pick`.
Since the introduction of fixup!/squash! commits, this idea was extended
to apply to "pick, possibly followed by a fixup/squash chain", i.e. an
exec would not be inserted between a `pick` and any of its corresponding
`fixup` or `squash` lines.
The current implementation uses a dirty trick to achieve that: it
assumes that there are only pick/fixup/squash commands, and then
*inserts* the `exec` lines before any `pick` but the first, and appends
a final one.
With the todo lists generated by `git rebase --rebase-merges`, this
simple implementation shows its problems: it produces the exact wrong
thing when there are `label`, `reset` and `merge` commands.
Let's change the implementation to do exactly what we want: look for
`pick` lines, skip any fixup/squash chains, and then insert the `exec`
line. Lather, rinse, repeat.
Note: we take pains to insert *before* comment lines whenever possible,
as empty commits are represented by commented-out pick lines (and we
want to insert a preceding pick's exec line *before* such a line, not
afterward).
While at it, also add `exec` lines after `merge` commands, because they
are similar in spirit to `pick` commands: they add new commits.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The --exec option's implementation is not really well-prepared for
--rebase-merges. Demonstrate this.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Previously, we introduced the `merge` command for use in todo lists,
to allow to recreate and modify branch topology.
For ease of implementation, and to make review easier, the initial
implementation only supported merge commits with exactly two parents.
This patch adds support for octopus merges, making use of the
just-introduced `-F <file>` option for the `git merge` command: to keep
things simple, we spawn a new Git command instead of trying to call a
library function, also opening an easier door to enhance `rebase
--rebase-merges` to optionally use a merge strategy different from
`recursive` for regular merges: this feature would use the same code
path as octopus merges and simply spawn a `git merge`.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When writing the todo script for --rebase-merges, we try to find a label
for certain commits. If the label ends up being a valid object ID, such
as when we merge a detached commit, we want to rewrite it so it is no
longer a valid object ID.
However, the code path that does this checks for its length to be
equivalent to GIT_SHA1_RAWSZ, which isn't correct, since what we are
reading is a hex object ID. Instead, check for the length being
equivalent to that of a hex object ID. Use the_hash_algo so this code
works regardless of the hash size.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Reported by Wink Saville: when rebasing with no-rebase-cousins, we
will want to refrain from rebasing all of them, even when they are
root commits.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When a user provides a todo list containing something like
reset [new root]
merge my-branch
let's do the same as if pulling into an orphan branch: simply
fast-forward.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the context of the new --rebase-merges mode, which was designed
specifically to allow for changing the existing branch topology
liberally, a user may want to extract commits into a completely fresh
branch that starts with a newly-created root commit.
This is now possible by inserting the command `reset [new root]` before
`pick`ing the commit that wants to become a root commit. Example:
reset [new root]
pick 012345 a commit that is about to become a root commit
pick 234567 this commit will have the previous one as parent
This does not conflict with other uses of the `reset` command because
`[new root]` is not (part of) a valid ref name: both the opening bracket
as well as the space are illegal in ref names.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When running `git rebase --rebase-merges` non-interactively with an
ancestor of HEAD as <upstream> (or leaving the todo list unmodified),
we would ideally recreate the exact same commits as before the rebase.
However, if there are commits in the commit range <upstream>.. that do not
have <upstream> as direct ancestor (i.e. if `git log <upstream>..` would
show commits that are omitted by `git log --ancestry-path <upstream>..`),
this is currently not the case: we would turn them into commits that have
<upstream> as direct ancestor.
Let's illustrate that with a diagram:
C
/ \
A - B - E - F
\ /
D
Currently, after running `git rebase -i --rebase-merges B`, the new branch
structure would be (pay particular attention to the commit `D`):
--- C' --
/ \
A - B ------ E' - F'
\ /
D'
This is not really preserving the branch topology from before! The
reason is that the commit `D` does not have `B` as ancestor, and
therefore it gets rebased onto `B`.
This is unintuitive behavior. Even worse, when recreating branch
structure, most use cases would appear to want cousins *not* to be
rebased onto the new base commit. For example, Git for Windows (the
heaviest user of the Git garden shears, which served as the blueprint
for --rebase-merges) frequently merges branches from `next` early, and
these branches certainly do *not* want to be rebased. In the example
above, the desired outcome would look like this:
--- C' --
/ \
A - B ------ E' - F'
\ /
-- D' --
Let's introduce the term "cousins" for such commits ("D" in the
example), and let's not rebase them by default. For hypothetical
use cases where cousins *do* need to be rebased, `git rebase
--rebase=merges=rebase-cousins` needs to be used.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `git merge` command does not allow merging commits that are already
reachable from HEAD: `git merge HEAD^`, for example, will report that we
are already up to date and not change a thing.
In an interactive rebase, such a merge could occur previously, e.g. when
competing (or slightly modified) versions of a patch series were applied
upstream, and the user had to `git rebase --skip` all of the local
commits, and the topic branch becomes "empty" as a consequence.
Let's teach the todo command `merge` to behave the same as `git merge`.
Seeing as it requires some low-level trickery to create such merges with
Git's commands in the first place, we do not even have to bother to
introduce an option to force `merge` to create such merge commits.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the previous patches, we implemented the basic functionality of the
`git rebase -i --rebase-merges` command, in particular the `merge`
command to create merge commits in the sequencer.
The interactive rebase is a lot more these days, though, than a simple
cherry-pick in a loop. For example, it calls the post-rewrite hook (if
any) after rebasing with a mapping of the old->new commits.
This patch implements the post-rewrite handling for the `merge` command
we just introduced. The other commands that were added recently (`label`
and `reset`) do not create new commits, therefore post-rewrite hooks do
not need to handle them.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This allows for rebases to be run in parallel in separate worktrees
(think: interrupted in the middle of one rebase, being asked to perform
a different rebase, adding a separate worktree just for that job).
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Once upon a time, this here developer thought: wouldn't it be nice if,
say, Git for Windows' patches on top of core Git could be represented as
a thicket of branches, and be rebased on top of core Git in order to
maintain a cherry-pick'able set of patch series?
The original attempt to answer this was: git rebase --preserve-merges.
However, that experiment was never intended as an interactive option,
and it only piggy-backed on git rebase --interactive because that
command's implementation looked already very, very familiar: it was
designed by the same person who designed --preserve-merges: yours truly.
Some time later, some other developer (I am looking at you, Andreas!
;-)) decided that it would be a good idea to allow --preserve-merges to
be combined with --interactive (with caveats!) and the Git maintainer
(well, the interim Git maintainer during Junio's absence, that is)
agreed, and that is when the glamor of the --preserve-merges design
started to fall apart rather quickly and unglamorously.
The reason? In --preserve-merges mode, the parents of a merge commit (or
for that matter, of *any* commit) were not stated explicitly, but were
*implied* by the commit name passed to the `pick` command.
This made it impossible, for example, to reorder commits. Not to mention
to move commits between branches or, deity forbid, to split topic branches
into two.
Alas, these shortcomings also prevented that mode (whose original
purpose was to serve Git for Windows' needs, with the additional hope
that it may be useful to others, too) from serving Git for Windows'
needs.
Five years later, when it became really untenable to have one unwieldy,
big hodge-podge patch series of partly related, partly unrelated patches
in Git for Windows that was rebased onto core Git's tags from time to
time (earning the undeserved wrath of the developer of the ill-fated
git-remote-hg series that first obsoleted Git for Windows' competing
approach, only to be abandoned without maintainer later) was really
untenable, the "Git garden shears" were born [*1*/*2*]: a script,
piggy-backing on top of the interactive rebase, that would first
determine the branch topology of the patches to be rebased, create a
pseudo todo list for further editing, transform the result into a real
todo list (making heavy use of the `exec` command to "implement" the
missing todo list commands) and finally recreate the patch series on
top of the new base commit.
That was in 2013. And it took about three weeks to come up with the
design and implement it as an out-of-tree script. Needless to say, the
implementation needed quite a few years to stabilize, all the while the
design itself proved itself sound.
With this patch, the goodness of the Git garden shears comes to `git
rebase -i` itself. Passing the `--rebase-merges` option will generate
a todo list that can be understood readily, and where it is obvious
how to reorder commits. New branches can be introduced by inserting
`label` commands and calling `merge <label>`. And once this mode will
have become stable and universally accepted, we can deprecate the design
mistake that was `--preserve-merges`.
Link *1*:
https://github.com/msysgit/msysgit/blob/master/share/msysGit/shears.sh
Link *2*:
https://github.com/git-for-windows/build-extra/blob/master/shears.sh
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
