Merge branch 'je/doc-rebase' into jch

gitster · gitster · commit 8b979a6048c4 · 2025-08-09T17:30:35.000-07:00
* je/doc-rebase:
  doc: git-rebase: update discussion of internals
  doc: git-rebase: move --onto explanation down
  doc: git rebase: clarify arguments syntax
  doc: git rebase: dedup merge conflict discussion
  doc: git-rebase: start with an example
diff --git a/Documentation/git-rebase.adoc b/Documentation/git-rebase.adoc
@@ -16,198 +16,101 @@ SYNOPSIS
 
 DESCRIPTION
 -----------
-If `<branch>` is specified, `git rebase` will perform an automatic
-`git switch <branch>` before doing anything else.  Otherwise
-it remains on the current branch.
+Transplant a series of commits onto a different starting point.
 
-If `<upstream>` is not specified, the upstream configured in
-`branch.<name>.remote` and `branch.<name>.merge` options will be used (see
-linkgit:git-config[1] for details) and the `--fork-point` option is
-assumed.  If you are currently not on any branch or if the current
-branch does not have a configured upstream, the rebase will abort.
-
-All changes made by commits in the current branch but that are not
-in `<upstream>` are saved to a temporary area.  This is the same set
-of commits that would be shown by `git log <upstream>..HEAD`; or by
-`git log 'fork_point'..HEAD`, if `--fork-point` is active (see the
-description on `--fork-point` below); or by `git log HEAD`, if the
-`--root` option is specified.
-
-The current branch is reset to `<upstream>` or `<newbase>` if the
-`--onto` option was supplied.  This has the exact same effect as
-`git reset --hard <upstream>` (or `<newbase>`). `ORIG_HEAD` is set
-to point at the tip of the branch before the reset.
-
-[NOTE]
-`ORIG_HEAD` is not guaranteed to still point to the previous branch tip
-at the end of the rebase if other commands that write that pseudo-ref
-(e.g. `git reset`) are used during the rebase. The previous branch tip,
-however, is accessible using the reflog of the current branch
-(i.e. `@{1}`, see linkgit:gitrevisions[7]).
-
-The commits that were previously saved into the temporary area are
-then reapplied to the current branch, one by one, in order. Note that
-any commits in `HEAD` which introduce the same textual changes as a commit
-in `HEAD..<upstream>` are omitted (i.e., a patch already accepted upstream
-with a different commit message or timestamp will be skipped).
-
-It is possible that a merge failure will prevent this process from being
-completely automatic.  You will have to resolve any such merge failure
-and run `git rebase --continue`.  Another option is to bypass the commit
-that caused the merge failure with `git rebase --skip`.  To check out the
-original `<branch>` and remove the `.git/rebase-apply` working files, use
-the command `git rebase --abort` instead.
-
-Assume the following history exists and the current branch is "topic":
+For example, imagine that you have been working on the `topic` branch in this
+history, and you want to "catch up" to the work done on the `master` branch.
 
 ------------
           A---B---C topic
          /
     D---E---F---G master
 ------------
 
-From this point, the result of either of the following commands:
-
-
-    git rebase master
-    git rebase master topic
-
-would be:
+You want to transplant the commits you made on `topic` since it diverged from
+`master` (i.e. A, B, and C), on top of the current `master`.  You can do this
+by running `git rebase master` while the `topic` branch is checked out.  If you
+want to rebase `topic` while on another branch, `git rebase master topic` is a
+shortcut for `git checkout topic && git rebase master`.
 
 ------------
                   A'--B'--C' topic
                  /
     D---E---F---G master
 ------------
 
-*NOTE:* The latter form is just a short-hand of `git checkout topic`
-followed by `git rebase master`. When rebase exits `topic` will
-remain the checked-out branch.
+If there is a merge conflict during this process, `git rebase` will stop at the
+first problematic commit and leave conflict markers. If this happens, you can do
+one of these things:
 
-If the upstream branch already contains a change you have made (e.g.,
-because you mailed a patch which was applied upstream), then that commit
-will be skipped and warnings will be issued (if the 'merge' backend is
-used).  For example, running `git rebase master` on the following
-history (in which `A'` and `A` introduce the same set of changes, but
-have different committer information):
+1. Resolve the conflict. You can use `git diff` to find the markers (<<<<<<)
+   and make edits to resolve the conflict. For each file you edit, you need to
+   tell Git that the conflict has been resolved. You can mark the conflict as
+   resolved with  `git add <filename>`. After resolving all of the conflicts,
+   you can continue the rebasing process with
 
-------------
-          A---B---C topic
-         /
-    D---E---A'---F master
-------------
+   git rebase --continue
 
-will result in:
+2. Stop the `git rebase` and return your branch to its original state with
 
-------------
-                   B'---C' topic
-                  /
-    D---E---A'---F master
-------------
+   git rebase --abort
 
-Here is how you would transplant a topic branch based on one
-branch to another, to pretend that you forked the topic branch
-from the latter branch, using `rebase --onto`.
+3. Skip the commit that caused the merge conflict with
 
-First let's assume your 'topic' is based on branch 'next'.
-For example, a feature developed in 'topic' depends on some
-functionality which is found in 'next'.
+   git rebase --skip
 
-------------
-    o---o---o---o---o  master
-         \
-          o---o---o---o---o  next
-                           \
-                            o---o---o  topic
-------------
-
-We want to make 'topic' forked from branch 'master'; for example,
-because the functionality on which 'topic' depends was merged into the
-more stable 'master' branch. We want our tree to look like this:
-
-------------
-    o---o---o---o---o  master
-        |            \
-        |             o'--o'--o'  topic
-         \
-          o---o---o---o---o  next
-------------
-
-We can get this using the following command:
-
-    git rebase --onto master next topic
-
-
-Another example of --onto option is to rebase part of a
-branch.  If we have the following situation:
+If you don't specify an `<upstream>` to rebase onto, the upstream configured in
+`branch.<name>.remote` and `branch.<name>.merge` options will be used (see
+linkgit:git-config[1] for details) and the `--fork-point` option is
+assumed.  If you are currently not on any branch or if the current
+branch does not have a configured upstream, the rebase will abort.
 
-------------
-                            H---I---J topicB
-                           /
-                  E---F---G  topicA
-                 /
-    A---B---C---D  master
-------------
+Here is a more detailed description of what `git rebase <upstream>` does:
 
-then the command
+First, it makes a list of all commits in the current branch that are not in
+`<upstream>`. This is the same set of commits that would be shown by `git log
+<upstream>..HEAD`. You can use `--fork-point` or `--root` to change how this
+list of commits is constructed.
 
-    git rebase --onto master topicA topicB
+Then it checks out `<upstream>` (or `<newbase>` if the `--onto` option was
+supplied) with the equivalent of `git switch --detach <upstream>`.
 
-would result in:
+Then it replays the commits, one by one, in order. This is similar to running
+`git cherry-pick <commit>` for each commit. See REBASING MERGES for how merges
+are handled.
 
-------------
-                 H'--I'--J'  topicB
-                /
-                | E---F---G  topicA
-                |/
-    A---B---C---D  master
-------------
+Finally, it updates your branch to point to the final commit with the equivalent
+of `git switch -C <branch>`.
 
-This is useful when topicB does not depend on topicA.
+[NOTE]
+`ORIG_HEAD` is set to point at the tip of the branch before the rebase.
+`ORIG_HEAD` is not guaranteed to still point to the previous branch tip
+at the end of the rebase if other commands that write that pseudo-ref
+(e.g. `git reset`) are used during the rebase. The previous branch tip,
+however, is accessible using the reflog of the current branch
+(i.e. `@{1}`, see linkgit:gitrevisions[7]).
 
-A range of commits could also be removed with rebase.  If we have
-the following situation:
+If the upstream branch already contains a change you have made (e.g.,
+because you mailed a patch which was applied upstream), then that commit
+will be skipped and warnings will be issued (if the 'merge' backend is
+used).  For example, running `git rebase master` on the following
+history (in which `A'` and `A` introduce the same set of changes, but
+have different committer information):
 
 ------------
-    E---F---G---H---I---J  topicA
+          A---B---C topic
+         /
+    D---E---A'---F master
 ------------
 
-then the command
-
-    git rebase --onto topicA~5 topicA~3 topicA
-
-would result in the removal of commits F and G:
+will result in:
 
 ------------
-    E---H'---I'---J'  topicA
+                   B'---C' topic
+                  /
+    D---E---A'---F master
 ------------
 
-This is useful if F and G were flawed in some way, or should not be
-part of topicA.  Note that the argument to `--onto` and the `<upstream>`
-parameter can be any valid commit-ish.
-
-In case of conflict, `git rebase` will stop at the first problematic commit
-and leave conflict markers in the tree.  You can use `git diff` to locate
-the markers (<<<<<<) and make edits to resolve the conflict.  For each
-file you edit, you need to tell Git that the conflict has been resolved,
-typically this would be done with
-
-
-    git add <filename>
-
-
-After resolving the conflict manually and updating the index with the
-desired resolution, you can continue the rebasing process with
-
-
-    git rebase --continue
-
-
-Alternatively, you can undo the 'git rebase' with
-
-
-    git rebase --abort
-
 MODE OPTIONS
 ------------
 
@@ -253,6 +156,8 @@ As a special case, you may use "A\...B" as a shortcut for the
 merge base of A and B if there is exactly one merge base. You can
 leave out at most one of A and B, in which case it defaults to HEAD.
 
+See TRANSPLANTING A TOPIC BRANCH WITH --ONTO below for examples.
+
 --keep-base::
 	Set the starting point at which to create the new commits to the
 	merge base of `<upstream>` and `<branch>`. Running
@@ -1031,6 +936,91 @@ consistent (they compile, pass the testsuite, etc.) you should use
 after each commit, test, and amend the commit if fixes are necessary.
 
 
+TRANSPLANTING A TOPIC BRANCH WITH --ONTO
+----------------------------------------
+
+Here is how you would transplant a topic branch based on one
+branch to another, to pretend that you forked the topic branch
+from the latter branch, using `rebase --onto`.
+
+First let's assume your 'topic' is based on branch 'next'.
+For example, a feature developed in 'topic' depends on some
+functionality which is found in 'next'.
+
+------------
+    o---o---o---o---o  master
+         \
+          o---o---o---o---o  next
+                           \
+                            o---o---o  topic
+------------
+
+We want to make 'topic' forked from branch 'master'; for example,
+because the functionality on which 'topic' depends was merged into the
+more stable 'master' branch. We want our tree to look like this:
+
+------------
+    o---o---o---o---o  master
+        |            \
+        |             o'--o'--o'  topic
+         \
+          o---o---o---o---o  next
+------------
+
+We can get this using the following command:
+
+    git rebase --onto master next topic
+
+
+Another example of --onto option is to rebase part of a
+branch.  If we have the following situation:
+
+------------
+                            H---I---J topicB
+                           /
+                  E---F---G  topicA
+                 /
+    A---B---C---D  master
+------------
+
+then the command
+
+    git rebase --onto master topicA topicB
+
+would result in:
+
+------------
+                 H'--I'--J'  topicB
+                /
+                | E---F---G  topicA
+                |/
+    A---B---C---D  master
+------------
+
+This is useful when topicB does not depend on topicA.
+
+A range of commits could also be removed with rebase.  If we have
+the following situation:
+
+------------
+    E---F---G---H---I---J  topicA
+------------
+
+then the command
+
+    git rebase --onto topicA~5 topicA~3 topicA
+
+would result in the removal of commits F and G:
+
+------------
+    E---H'---I'---J'  topicA
+------------
+
+This is useful if F and G were flawed in some way, or should not be
+part of topicA.  Note that the argument to `--onto` and the `<upstream>`
+parameter can be any valid commit-ish.
+
+
 RECOVERING FROM UPSTREAM REBASE
 -------------------------------
 
