replace: check mergetags when using --graft

When using --graft, with a mergetag in the original
commit, we should check that the commit pointed to by
the mergetag is still a parent of then new commit we
create, otherwise the mergetag could be misleading.

If the commit pointed to by the mergetag is no more
a parent of the new commit, we could remove the
mergetag, but in this case there is a good chance
that the title or other elements of the commit might
also be misleading. So let's just error out and
suggest to use --edit instead on the commit.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/replace.c b/builtin/replace.c
index 52f73ce55752a2b5bc24173c572a80f73f916264..d29026fe215f428824753aba12f2e5782607cf2c 100644 (file)
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -13,6 +13,7 @@
 #include "refs.h"
 #include "parse-options.h"
 #include "run-command.h"
 #include "refs.h"
 #include "parse-options.h"
 #include "run-command.h"

+#include "tag.h"

 
 static const char * const git_replace_usage[] = {
        N_("git replace [-f] <object> <replacement>"),
 
 static const char * const git_replace_usage[] = {
        N_("git replace [-f] <object> <replacement>"),


@@ -325,6 +326,50 @@ static void replace_parents(struct strbuf *buf, int argc, const char **argv)
        strbuf_release(&new_parents);
 }
 
        strbuf_release(&new_parents);
 }
 

+struct check_mergetag_data {
+       int argc;
+       const char **argv;
+};
+
+static void check_one_mergetag(struct commit *commit,
+                              struct commit_extra_header *extra,
+                              void *data)
+{
+       struct check_mergetag_data *mergetag_data = (struct check_mergetag_data *)data;
+       const char *ref = mergetag_data->argv[0];
+       unsigned char tag_sha1[20];
+       struct tag *tag;
+       int i;
+
+       hash_sha1_file(extra->value, extra->len, typename(OBJ_TAG), tag_sha1);
+       tag = lookup_tag(tag_sha1);
+       if (!tag)
+               die(_("bad mergetag in commit '%s'"), ref);
+       if (parse_tag_buffer(tag, extra->value, extra->len))
+               die(_("malformed mergetag in commit '%s'"), ref);
+
+       /* iterate over new parents */
+       for (i = 1; i < mergetag_data->argc; i++) {
+               unsigned char sha1[20];
+               if (get_sha1(mergetag_data->argv[i], sha1) < 0)
+                       die(_("Not a valid object name: '%s'"), mergetag_data->argv[i]);
+               if (!hashcmp(tag->tagged->sha1, sha1))
+                       return; /* found */
+       }
+
+       die(_("original commit '%s' contains mergetag '%s' that is discarded; "
+             "use --edit instead of --graft"), ref, sha1_to_hex(tag_sha1));
+}
+
+static void check_mergetags(struct commit *commit, int argc, const char **argv)
+{
+       struct check_mergetag_data mergetag_data;
+
+       mergetag_data.argc = argc;
+       mergetag_data.argv = argv;
+       for_each_mergetag(check_one_mergetag, commit, &mergetag_data);
+}
+

 static int create_graft(int argc, const char **argv, int force)
 {
        unsigned char old[20], new[20];
 static int create_graft(int argc, const char **argv, int force)
 {
        unsigned char old[20], new[20];


@@ -349,6 +394,8 @@ static int create_graft(int argc, const char **argv, int force)
                warning(_("the signature will be removed in the replacement commit!"));
        }
 
                warning(_("the signature will be removed in the replacement commit!"));
        }
 

+       check_mergetags(commit, argc, argv);
+

        if (write_sha1_file(buf.buf, buf.len, commit_type, new))
                die(_("could not write replacement commit for: '%s'"), old_ref);
 
        if (write_sha1_file(buf.buf, buf.len, commit_type, new))
                die(_("could not write replacement commit for: '%s'"), old_ref);