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-rw-r--r--builtin-checkout.c7
-rw-r--r--cache.h1
-rw-r--r--sha1_name.c42
-rwxr-xr-xt/t2012-checkout-last.sh27
4 files changed, 74 insertions, 3 deletions
diff --git a/builtin-checkout.c b/builtin-checkout.c
index da04eed391..fe7c8584ca 100644
--- a/builtin-checkout.c
+++ b/builtin-checkout.c
@@ -689,7 +689,10 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
* case 3: git checkout <something> [<paths>]
*
* With no paths, if <something> is a commit, that is to
- * switch to the branch or detach HEAD at it.
+ * switch to the branch or detach HEAD at it. As a special case,
+ * if <something> is A...B (missing A or B means HEAD but you can
+ * omit at most one side), and if there is a unique merge base
+ * between A and B, A...B names that merge base.
*
* With no paths, if <something> is _not_ a commit, no -t nor -b
* was given, and there is a tracking branch whose name is
@@ -715,7 +718,7 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
if (!strcmp(arg, "-"))
arg = "@{-1}";
- if (get_sha1(arg, rev)) {
+ if (get_sha1_mb(arg, rev)) {
if (has_dash_dash) /* case (1) */
die("invalid reference: %s", arg);
if (!patch_mode &&
diff --git a/cache.h b/cache.h
index 71a731dbc9..f8df15a060 100644
--- a/cache.h
+++ b/cache.h
@@ -703,6 +703,7 @@ extern const char *resolve_ref(const char *path, unsigned char *sha1, int, int *
extern int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref);
extern int dwim_log(const char *str, int len, unsigned char *sha1, char **ref);
extern int interpret_branch_name(const char *str, struct strbuf *);
+extern int get_sha1_mb(const char *str, unsigned char *sha1);
extern int refname_match(const char *abbrev_name, const char *full_name, const char **rules);
extern const char *ref_rev_parse_rules[];
diff --git a/sha1_name.c b/sha1_name.c
index 44bb62d270..d5a240cf07 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -794,6 +794,48 @@ release_return:
return retval;
}
+int get_sha1_mb(const char *name, unsigned char *sha1)
+{
+ struct commit *one, *two;
+ struct commit_list *mbs;
+ unsigned char sha1_tmp[20];
+ const char *dots;
+ int st;
+
+ dots = strstr(name, "...");
+ if (!dots)
+ return get_sha1(name, sha1);
+ if (dots == name)
+ st = get_sha1("HEAD", sha1_tmp);
+ else {
+ struct strbuf sb;
+ strbuf_init(&sb, dots - name);
+ strbuf_add(&sb, name, dots - name);
+ st = get_sha1(sb.buf, sha1_tmp);
+ strbuf_release(&sb);
+ }
+ if (st)
+ return st;
+ one = lookup_commit_reference_gently(sha1_tmp, 0);
+ if (!one)
+ return -1;
+
+ if (get_sha1(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
+ return -1;
+ two = lookup_commit_reference_gently(sha1_tmp, 0);
+ if (!two)
+ return -1;
+ mbs = get_merge_bases(one, two, 1);
+ if (!mbs || mbs->next)
+ st = -1;
+ else {
+ st = 0;
+ hashcpy(sha1, mbs->item->object.sha1);
+ }
+ free_commit_list(mbs);
+ return st;
+}
+
/*
* This is like "get_sha1_basic()", except it allows "sha1 expressions",
* notably "xyz^" for "parent of xyz"
diff --git a/t/t2012-checkout-last.sh b/t/t2012-checkout-last.sh
index 87b30a268c..b44de9dc62 100755
--- a/t/t2012-checkout-last.sh
+++ b/t/t2012-checkout-last.sh
@@ -1,6 +1,6 @@
#!/bin/sh
-test_description='checkout can switch to last branch'
+test_description='checkout can switch to last branch and merge base'
. ./test-lib.sh
@@ -91,4 +91,29 @@ test_expect_success 'switch to twelfth from the last' '
test "z$(git symbolic-ref HEAD)" = "zrefs/heads/branch13"
'
+test_expect_success 'merge base test setup' '
+ git checkout -b another other &&
+ echo "hello again" >>world &&
+ git add world &&
+ git commit -m third
+'
+
+test_expect_success 'another...master' '
+ git checkout another &&
+ git checkout another...master &&
+ test "z$(git rev-parse --verify HEAD)" = "z$(git rev-parse --verify master^)"
+'
+
+test_expect_success '...master' '
+ git checkout another &&
+ git checkout ...master &&
+ test "z$(git rev-parse --verify HEAD)" = "z$(git rev-parse --verify master^)"
+'
+
+test_expect_success 'master...' '
+ git checkout another &&
+ git checkout master... &&
+ test "z$(git rev-parse --verify HEAD)" = "z$(git rev-parse --verify master^)"
+'
+
test_done