Usually you cannot revert a merge because you do not know which
side of the merge should be considered the mainline (iow, what
change to reverse).
With this patch, cherry-pick and revert learn -m (--mainline)
option that lets you specify the parent number (starting from 1)
of the mainline, so that you can:
git revert -m 1 $merge
to reverse the changes introduced by the $merge commit relative
to its first parent, and:
git cherry-pick -m 2 $merge
to replay the changes introduced by the $merge commit relative
to its second parent.
Signed-off-by: Junio C Hamano <gitster@xxxxxxxxx>
---
Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> writes:
> On Tue, 23 Oct 2007, Junio C Hamano wrote:
>>
>> Desire to revert an octopus would, as you demonstrated, often be
>> to revert only one arm, but I think allowing to revert a twohead
>> merge should be trivial. If we define "reverting a merge" to
>> always revert all arms, then this should suffice.
>
> The only reason I don't like this is that it kind of assumes that the
> mainline is the first parent.
>
> Maybe I'd like to revert a merge, but I want to revert a merge that
> somebody *else* did, and maybe it was the first-hand parent I don't like.
>
> Those kinds of issues don't exist with non-merge commits: there's never
> any question "which side" to revert.
Fair enough. How about this?
Documentation/git-cherry-pick.txt | 9 +++++++-
Documentation/git-revert.txt | 9 +++++++-
builtin-revert.c | 42 ++++++++++++++++++++++++++++++------
git-compat-util.h | 13 +++++++++++
4 files changed, 64 insertions(+), 9 deletions(-)
diff --git a/Documentation/git-cherry-pick.txt b/Documentation/git-cherry-pick.txt
index 76a2edf..937c4a7 100644
--- a/Documentation/git-cherry-pick.txt
+++ b/Documentation/git-cherry-pick.txt
@@ -7,7 +7,7 @@ git-cherry-pick - Apply the change introduced by an existing commit
SYNOPSIS
--------
-'git-cherry-pick' [--edit] [-n] [-x] <commit>
+'git-cherry-pick' [--edit] [-n] [-m parent-number] [-x] <commit>
DESCRIPTION
-----------
@@ -44,6 +44,13 @@ OPTIONS
described above, and `-r` was to disable it. Now the
default is not to do `-x` so this option is a no-op.
+-m parent-number|--mainline parent-number::
+ Usually you cannot revert a merge because you do not know which
+ side of the merge should be considered the mainline. This
+ option specifies the parent number (starting from 1) of
+ the mainline and allows cherry-pick to replay the change
+ relative to the specified parent.
+
-n|--no-commit::
Usually the command automatically creates a commit with
a commit log message stating which commit was
diff --git a/Documentation/git-revert.txt b/Documentation/git-revert.txt
index 69db498..3457c40 100644
--- a/Documentation/git-revert.txt
+++ b/Documentation/git-revert.txt
@@ -7,7 +7,7 @@ git-revert - Revert an existing commit
SYNOPSIS
--------
-'git-revert' [--edit | --no-edit] [-n] <commit>
+'git-revert' [--edit | --no-edit] [-n] [-m parent-number] <commit>
DESCRIPTION
-----------
@@ -27,6 +27,13 @@ OPTIONS
message prior committing the revert. This is the default if
you run the command from a terminal.
+-m parent-number|--mainline parent-number::
+ Usually you cannot revert a merge because you do not know which
+ side of the merge should be considered the mainline. This
+ option specifies the parent number (starting from 1) of
+ the mainline and allows revert to reverse the change
+ relative to the specified parent.
+
--no-edit::
With this option, `git-revert` will not start the commit
message editor.
diff --git a/builtin-revert.c b/builtin-revert.c
index a655c8e..bfed69d 100644
--- a/builtin-revert.c
+++ b/builtin-revert.c
@@ -19,9 +19,9 @@
* Copyright (c) 2005 Junio C Hamano
*/
-static const char *revert_usage = "git-revert [--edit | --no-edit] [-n] <commit-ish>";
+static const char *revert_usage = "git-revert [--edit | --no-edit] [-n] [-m parent-number] <commit-ish>";
-static const char *cherry_pick_usage = "git-cherry-pick [--edit] [-n] [-r] [-x] <commit-ish>";
+static const char *cherry_pick_usage = "git-cherry-pick [--edit] [-n] [-m parent-number] [-r] [-x] <commit-ish>";
static int edit;
static int replay;
@@ -29,6 +29,7 @@ static enum { REVERT, CHERRY_PICK } action;
static int no_commit;
static struct commit *commit;
static int needed_deref;
+static int mainline;
static const char *me;
@@ -58,6 +59,12 @@ static void parse_options(int argc, const char **argv)
else if (!strcmp(arg, "-x") || !strcmp(arg, "--i-really-want-"
"to-expose-my-private-commit-object-name"))
replay = 0;
+ else if (!strcmp(arg, "-m") || !strcmp(arg, "--mainline")) {
+ if (++i >= argc ||
+ strtol_i(argv[i], 10, &mainline) ||
+ mainline <= 0)
+ usage(usage_str);
+ }
else if (strcmp(arg, "-r"))
usage(usage_str);
}
@@ -234,7 +241,7 @@ static int merge_recursive(const char *base_sha1,
static int revert_or_cherry_pick(int argc, const char **argv)
{
unsigned char head[20];
- struct commit *base, *next;
+ struct commit *base, *next, *parent;
int i;
char *oneline, *reencoded_message = NULL;
const char *message, *encoding;
@@ -269,8 +276,29 @@ static int revert_or_cherry_pick(int argc, const char **argv)
if (!commit->parents)
die ("Cannot %s a root commit", me);
- if (commit->parents->next)
- die ("Cannot %s a multi-parent commit.", me);
+ if (commit->parents->next) {
+ /* Reverting or cherry-picking a merge commit */
+ int cnt;
+ struct commit_list *p;
+
+ if (!mainline)
+ die("Commit %s is a merge but no -m option was given.",
+ sha1_to_hex(commit->object.sha1));
+
+ for (cnt = 1, p = commit->parents;
+ cnt != mainline && p;
+ cnt++)
+ p = p->next;
+ if (cnt != mainline || !p)
+ die("Commit %s does not have parent %d",
+ sha1_to_hex(commit->object.sha1), mainline);
+ parent = p->item;
+ } else if (0 < mainline)
+ die("Mainline was specified but commit %s is not a merge.",
+ sha1_to_hex(commit->object.sha1));
+ else
+ parent = commit->parents->item;
+
if (!(message = commit->buffer))
die ("Cannot get commit message for %s",
sha1_to_hex(commit->object.sha1));
@@ -299,14 +327,14 @@ static int revert_or_cherry_pick(int argc, const char **argv)
char *oneline_body = strchr(oneline, ' ');
base = commit;
- next = commit->parents->item;
+ next = parent;
add_to_msg("Revert \"");
add_to_msg(oneline_body + 1);
add_to_msg("\"\n\nThis reverts commit ");
add_to_msg(sha1_to_hex(commit->object.sha1));
add_to_msg(".\n");
} else {
- base = commit->parents->item;
+ base = parent;
next = commit;
set_author_ident_env(message);
add_message_to_msg(message);
diff --git a/git-compat-util.h b/git-compat-util.h
index f23d934..a12c36b 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -376,4 +376,17 @@ static inline int strtoul_ui(char const *s, int base, unsigned int *result)
return 0;
}
+static inline int strtol_i(char const *s, int base, int *result)
+{
+ long ul;
+ char *p;
+
+ errno = 0;
+ ul = strtol(s, &p, base);
+ if (errno || *p || p == s || (int) ul != ul)
+ return -1;
+ *result = ul;
+ return 0;
+}
+
#endif
--
1.5.3.4.1324.ga7925
-
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