[PATCH v2 02/11] builtin rebase: support `git rebase --onto A...B`

From: Pratik Karki via GitGitGadget <gitgitgadget@gmail.com>
Date: Sep 4, 2018, 21:27 UTC
Message-ID: <f9826ab58f73d4ebca4d69134f4f75b5831bbd74.1536096424.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.32.v2.git.gitgitgadget@gmail.com>

From: Pratik Karki <predatoramigo@gmail.com>

This commit implements support for an --onto argument that is actually a "symmetric range" i.e. `<rev1>...<rev2>`.

The equivalent shell script version of the code offers two different error messages for the cases where there is no merge base vs more than one merge base.

Though it would be nice to retain this distinction, dropping it makes it possible to simply use the `get_oid_mb()` function. Besides, it happens rarely in real-world scenarios.

Therefore, in the interest of keeping the code less complex, let's just use that function, and live with an error message that does not distinguish between those two error conditions.

Signed-off-by: Pratik Karki <predatoramigo@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 builtin/rebase.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/builtin/rebase.c b/builtin/rebase.c
index 742ed31498..38c496dd10 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -17,6 +17,7 @@
 #include "unpack-trees.h"
 #include "lockfile.h"
 #include "parse-options.h"
+#include "commit.h"
 
 static char const * const builtin_rebase_usage[] = {
 	N_("git rebase [-i] [options] [--exec <cmd>] [--onto <newbase>] "
@@ -311,6 +312,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 	int ret, flags;
 	struct strbuf msg = STRBUF_INIT;
 	struct strbuf revisions = STRBUF_INIT;
+	struct object_id merge_base;
 	struct option builtin_rebase_options[] = {
 		OPT_STRING(0, "onto", &options.onto_name,
 			   N_("revision"),
@@ -387,7 +389,11 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 	if (!options.onto_name)
 		options.onto_name = options.upstream_name;
 	if (strstr(options.onto_name, "...")) {
-		die("TODO");
+		if (get_oid_mb(options.onto_name, &merge_base) < 0)
+			die(_("'%s': need exactly one merge base"),
+			    options.onto_name);
+		options.onto = lookup_commit_or_die(&merge_base,
+						    options.onto_name);
 	} else {
 		options.onto = peel_committish(options.onto_name);
 		if (!options.onto)

-- 
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