merge: handle FETCH_HEAD internally

The collect_parents() function now is responsible for

1. parsing the commits given on the command line into a list of
commits to be merged;

2. filtering these parents into independent ones; and

3. optionally calling fmt_merge_msg() via prepare_merge_message()
to prepare an auto-generated merge log message, using fake
contents that FETCH_HEAD would have had if these commits were
fetched from the current repository with "git pull . $args..."

Make "git merge FETCH_HEAD" to be the same as the traditional

git merge "$(git fmt-merge-msg <.git/FETCH_HEAD)" $commits

invocation of the command in "git pull", where $commits are the ones
that appear in FETCH_HEAD that are not marked as not-for-merge, by
making it do a bit more, specifically:

- noticing "FETCH_HEAD" is the only "commit" on the command line
and picking the commits that are not marked as not-for-merge as
the list of commits to be merged (substitute for step #1 above);

- letting the resulting list fed to step #2 above;

- doing the step #3 above, using the contents of the FETCH_HEAD
instead of fake contents crafted from the list of commits parsed
in the step #1 above.

Note that this changes the semantics.  "git merge FETCH_HEAD" has
always behaved as if the first commit in the FETCH_HEAD file were
directly specified on the command line, creating a two-way merge
whose auto-generated merge log said "merge commit xyz".  With this
change, if the previous fetch was to grab multiple branches (e.g.
"git fetch $there topic-a topic-b"), the new world order is to
create an octopus, behaving as if "git pull $there topic-a topic-b"
were run.  This is a deliberate change to make that happen, and
can be seen in the changes to t3033 tests.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-merge.txt b/Documentation/git-merge.txt
index cf2c374b710673e891f8337cb9bcc90d72be460a..d9aa6b6f118b10604f2579af3f987dfe8e4e8184 100644 (file)
--- a/Documentation/git-merge.txt
+++ b/Documentation/git-merge.txt
@@ -104,6 +104,10 @@ commit or stash your changes before running 'git merge'.
 If no commit is given from the command line, merge the remote-tracking
 branches that the current branch is configured to use as its upstream.
 See also the configuration section of this manual page.
++
+When `FETCH_HEAD` (and no other commit) is specified, the branches
+recorded in the `.git/FETCH_HEAD` file by the previous invocation
+of `git fetch` for merging are merged to the current branch.
 
 
 PRE-MERGE CHECKS

diff --git a/builtin/merge.c b/builtin/merge.c
index eb3be6817efa24584deaae333130971173577ce2..42f9fcc1745c05f13d685981b14a9ac22f82dc77 100644 (file)
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -505,28 +505,6 @@ static void merge_name(const char *remote, struct strbuf *msg)
                strbuf_release(&truname);
        }
 
-       if (!strcmp(remote, "FETCH_HEAD") &&
-                       !access(git_path("FETCH_HEAD"), R_OK)) {
-               const char *filename;
-               FILE *fp;
-               struct strbuf line = STRBUF_INIT;
-               char *ptr;
-
-               filename = git_path("FETCH_HEAD");
-               fp = fopen(filename, "r");
-               if (!fp)
-                       die_errno(_("could not open '%s' for reading"),
-                                 filename);
-               strbuf_getline(&line, fp, '\n');
-               fclose(fp);
-               ptr = strstr(line.buf, "\tnot-for-merge\t");
-               if (ptr)
-                       strbuf_remove(&line, ptr-line.buf+1, 13);
-               strbuf_addbuf(msg, &line);
-               strbuf_release(&line);
-               goto cleanup;
-       }
-
        if (remote_head->util) {
                struct merge_remote_desc *desc;
                desc = merge_remote_util(remote_head);
@@ -1090,6 +1068,60 @@ static void prepare_merge_message(struct strbuf *merge_names, struct strbuf *mer
                strbuf_setlen(merge_msg, merge_msg->len - 1);
 }
 
+static void handle_fetch_head(struct commit_list **remotes, struct strbuf *merge_names)
+{
+       const char *filename;
+       int fd, pos, npos;
+       struct strbuf fetch_head_file = STRBUF_INIT;
+
+       if (!merge_names)
+               merge_names = &fetch_head_file;
+
+       filename = git_path("FETCH_HEAD");
+       fd = open(filename, O_RDONLY);
+       if (fd < 0)
+               die_errno(_("could not open '%s' for reading"), filename);
+
+       if (strbuf_read(merge_names, fd, 0) < 0)
+               die_errno(_("could not read '%s'"), filename);
+       if (close(fd) < 0)
+               die_errno(_("could not close '%s'"), filename);
+
+       for (pos = 0; pos < merge_names->len; pos = npos) {
+               unsigned char sha1[20];
+               char *ptr;
+               struct commit *commit;
+
+               ptr = strchr(merge_names->buf + pos, '\n');
+               if (ptr)
+                       npos = ptr - merge_names->buf + 1;
+               else
+                       npos = merge_names->len;
+
+               if (npos - pos < 40 + 2 ||
+                   get_sha1_hex(merge_names->buf + pos, sha1))
+                       commit = NULL; /* bad */
+               else if (memcmp(merge_names->buf + pos + 40, "\t\t", 2))
+                       continue; /* not-for-merge */
+               else {
+                       char saved = merge_names->buf[pos + 40];
+                       merge_names->buf[pos + 40] = '\0';
+                       commit = get_merge_parent(merge_names->buf + pos);
+                       merge_names->buf[pos + 40] = saved;
+               }
+               if (!commit) {
+                       if (ptr)
+                               *ptr = '\0';
+                       die("not something we can merge in %s: %s",
+                           filename, merge_names->buf + pos);
+               }
+               remotes = &commit_list_insert(commit, remotes)->next;
+       }
+
+       if (merge_names == &fetch_head_file)
+               strbuf_release(&fetch_head_file);
+}
+
 static struct commit_list *collect_parents(struct commit *head_commit,
                                           int *head_subsumed,
                                           int argc, const char **argv,
@@ -1105,21 +1137,27 @@ static struct commit_list *collect_parents(struct commit *head_commit,
 
        if (head_commit)
                remotes = &commit_list_insert(head_commit, remotes)->next;
-       for (i = 0; i < argc; i++) {
-               struct commit *commit = get_merge_parent(argv[i]);
-               if (!commit)
-                       help_unknown_ref(argv[i], "merge",
-                                        "not something we can merge");
-               remotes = &commit_list_insert(commit, remotes)->next;
-       }
 
-       remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
+       if (argc == 1 && !strcmp(argv[0], "FETCH_HEAD")) {
+               handle_fetch_head(remotes, autogen);
+               remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
+       } else {
+               for (i = 0; i < argc; i++) {
+                       struct commit *commit = get_merge_parent(argv[i]);
+                       if (!commit)
+                               help_unknown_ref(argv[i], "merge",
+                                                "not something we can merge");
+                       remotes = &commit_list_insert(commit, remotes)->next;
+               }
+               remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
+               if (autogen) {
+                       struct commit_list *p;
+                       for (p = remoteheads; p; p = p->next)
+                               merge_name(merge_remote_util(p->item)->name, autogen);
+               }
+       }
 
        if (autogen) {
-               struct commit_list *p;
-               for (p = remoteheads; p; p = p->next)
-                       merge_name(merge_remote_util(p->item)->name, autogen);
-
                prepare_merge_message(autogen, merge_msg);
                strbuf_release(autogen);
        }

diff --git a/t/t3033-merge-toplevel.sh b/t/t3033-merge-toplevel.sh
index 9d92d3c1a27d08f15ffa2510b5017e32aecfce94..46aadc410bc470d9279ed1fd3ee72583d0963d30 100755 (executable)
--- a/t/t3033-merge-toplevel.sh
+++ b/t/t3033-merge-toplevel.sh
@@ -77,7 +77,7 @@ test_expect_success 'merge octopus, non-fast-forward' '
 
 # The same set with FETCH_HEAD
 
-test_expect_failure 'merge FETCH_HEAD octopus into void' '
+test_expect_success 'merge FETCH_HEAD octopus into void' '
        t3033_reset &&
        git checkout --orphan test &&
        git rm -fr . &&
@@ -88,7 +88,7 @@ test_expect_failure 'merge FETCH_HEAD octopus into void' '
        test_must_fail git rev-parse HEAD
 '
 
-test_expect_failure 'merge FETCH_HEAD octopus fast-forward (ff)' '
+test_expect_success 'merge FETCH_HEAD octopus fast-forward (ff)' '
        t3033_reset &&
        git reset --hard one &&
        git fetch . left right &&
@@ -100,7 +100,7 @@ test_expect_failure 'merge FETCH_HEAD octopus fast-forward (ff)' '
        test_cmp expect actual
 '
 
-test_expect_failure 'merge FETCH_HEAD octopus non-fast-forward (ff)' '
+test_expect_success 'merge FETCH_HEAD octopus non-fast-forward (ff)' '
        t3033_reset &&
        git reset --hard one &&
        git fetch . left right &&
@@ -112,7 +112,7 @@ test_expect_failure 'merge FETCH_HEAD octopus non-fast-forward (ff)' '
        test_cmp expect actual
 '
 
-test_expect_failure 'merge FETCH_HEAD octopus fast-forward (does not ff)' '
+test_expect_success 'merge FETCH_HEAD octopus fast-forward (does not ff)' '
        t3033_reset &&
        git fetch . left right &&
        git merge FETCH_HEAD &&
@@ -123,7 +123,7 @@ test_expect_failure 'merge FETCH_HEAD octopus fast-forward (does not ff)' '
        test_cmp expect actual
 '
 
-test_expect_failure 'merge FETCH_HEAD octopus non-fast-forward' '
+test_expect_success 'merge FETCH_HEAD octopus non-fast-forward' '
        t3033_reset &&
        git fetch . left right &&
        git merge --no-ff FETCH_HEAD &&