sequencer: learn about the special "fake root commit" handling
When an interactive rebase wants to recreate a root commit, it - first creates a new, empty root commit, - checks it out, - converts the next `pick` command so that it amends the empty root commit Introduce support in the sequencer to handle such an empty root commit, by looking for the file <GIT_DIR>/rebase-merge/squash-onto; if it exists and contains a commit name, the sequencer will compare the HEAD to said root commit, and if identical, a new root commit will be created. While converting scripted code into proper, portable C, we also do away with the old "amend with an empty commit message, then cherry-pick without committing, then amend again" dance and replace it with code that uses the internal API properly to do exactly what we want: create a new root commit. To keep the implementation simple, we always spawn `git commit` to create new root commits. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Johannes Schindelin committed
May 4, 2018 at 01:01 UTC
d87d48b2e033e8a8d39afbe7cb5eea331bbe47a6
2 files changed
+125
-3
sequencer.c
+121
-3
@@ -125,6 +125,12 @@ static GIT_PATH_FUNC(rebase_path_rewritten_list, "rebase-merge/rewritten-list")
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static GIT_PATH_FUNC(rebase_path_rewritten_pending,
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"rebase-merge/rewritten-pending")
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+/*
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+ * The path of the file containig the OID of the "squash onto" commit, i.e.
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+ * the dummy commit used for `reset [new root]`.
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+ */
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+static GIT_PATH_FUNC(rebase_path_squash_onto, "rebase-merge/squash-onto")
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+
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/*
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* The path of the file listing refs that need to be deleted after the rebase
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* finishes. This is used by the `label` command to record the need for cleanup.
@@ -470,7 +476,8 @@ static int fast_forward_to(const struct object_id *to, const struct object_id *f
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transaction = ref_transaction_begin(&err);
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if (!transaction ||
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ref_transaction_update(transaction, "HEAD",
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- to, unborn ? &null_oid : from,
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+ to, unborn && !is_rebase_i(opts) ?
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+ &null_oid : from,
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0, sb.buf, &err) ||
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ref_transaction_commit(transaction, &err)) {
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ref_transaction_free(transaction);
@@ -692,6 +699,52 @@ static char *get_author(const char *message)
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return NULL;
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}
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+/* Read author-script and return an ident line (author <email> timestamp) */
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+static const char *read_author_ident(struct strbuf *buf)
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+{
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+ const char *keys[] = {
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+ "GIT_AUTHOR_NAME=", "GIT_AUTHOR_EMAIL=", "GIT_AUTHOR_DATE="
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+ };
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+ char *in, *out, *eol;
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+ int i = 0, len;
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+
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+ if (strbuf_read_file(buf, rebase_path_author_script(), 256) <= 0)
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+ return NULL;
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+
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+ /* dequote values and construct ident line in-place */
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+ for (in = out = buf->buf; i < 3 && in - buf->buf < buf->len; i++) {
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+ if (!skip_prefix(in, keys[i], (const char **)&in)) {
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+ warning("could not parse '%s' (looking for '%s'",
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+ rebase_path_author_script(), keys[i]);
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+ return NULL;
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+ }
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+
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+ eol = strchrnul(in, '\n');
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+ *eol = '\0';
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+ sq_dequote(in);
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+ len = strlen(in);
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+
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+ if (i > 0) /* separate values by spaces */
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+ *(out++) = ' ';
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+ if (i == 1) /* email needs to be surrounded by <...> */
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+ *(out++) = '<';
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+ memmove(out, in, len);
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+ out += len;
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+ if (i == 1) /* email needs to be surrounded by <...> */
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+ *(out++) = '>';
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+ in = eol + 1;
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+ }
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+
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+ if (i < 3) {
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+ warning("could not parse '%s' (looking for '%s')",
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+ rebase_path_author_script(), keys[i]);
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+ return NULL;
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+ }
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+
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+ buf->len = out - buf->buf;
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+ return buf->buf;
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+}
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+
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static const char staged_changes_advice[] =
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N_("you have staged changes in your working tree\n"
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"If these changes are meant to be squashed into the previous commit, run:\n"
@@ -711,6 +764,7 @@ N_("you have staged changes in your working tree\n"
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#define AMEND_MSG (1<<2)
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#define CLEANUP_MSG (1<<3)
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#define VERIFY_MSG (1<<4)
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+#define CREATE_ROOT_COMMIT (1<<5)
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/*
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* If we are cherry-pick, and if the merge did not result in
@@ -730,6 +784,40 @@ static int run_git_commit(const char *defmsg, struct replay_opts *opts,
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struct child_process cmd = CHILD_PROCESS_INIT;
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const char *value;
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+ if (flags & CREATE_ROOT_COMMIT) {
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+ struct strbuf msg = STRBUF_INIT, script = STRBUF_INIT;
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+ const char *author = is_rebase_i(opts) ?
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+ read_author_ident(&script) : NULL;
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+ struct object_id root_commit, *cache_tree_oid;
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+ int res = 0;
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+
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+ if (!defmsg)
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+ BUG("root commit without message");
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+
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+ if (!(cache_tree_oid = get_cache_tree_oid()))
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+ res = -1;
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+
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+ if (!res)
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+ res = strbuf_read_file(&msg, defmsg, 0);
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+
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+ if (res <= 0)
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+ res = error_errno(_("could not read '%s'"), defmsg);
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+ else
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+ res = commit_tree(msg.buf, msg.len, cache_tree_oid,
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+ NULL, &root_commit, author,
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+ opts->gpg_sign);
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+
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+ strbuf_release(&msg);
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+ strbuf_release(&script);
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+ if (!res) {
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+ update_ref(NULL, "CHERRY_PICK_HEAD", &root_commit, NULL,
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+ REF_NO_DEREF, UPDATE_REFS_MSG_ON_ERR);
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+ res = update_ref(NULL, "HEAD", &root_commit, NULL, 0,
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+ UPDATE_REFS_MSG_ON_ERR);
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+ }
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+ return res < 0 ? error(_("writing root commit")) : 0;
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+ }
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+
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cmd.git_cmd = 1;
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if (is_rebase_i(opts)) {
@@ -1216,7 +1304,8 @@ static int do_commit(const char *msg_file, const char *author,
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{
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int res = 1;
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- if (!(flags & EDIT_MSG) && !(flags & VERIFY_MSG)) {
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+ if (!(flags & EDIT_MSG) && !(flags & VERIFY_MSG) &&
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+ !(flags & CREATE_ROOT_COMMIT)) {
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struct object_id oid;
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struct strbuf sb = STRBUF_INIT;
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@@ -1369,6 +1458,22 @@ static int is_fixup(enum todo_command command)
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return command == TODO_FIXUP || command == TODO_SQUASH;
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}
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+/* Does this command create a (non-merge) commit? */
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+static int is_pick_or_similar(enum todo_command command)
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+{
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+ switch (command) {
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+ case TODO_PICK:
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+ case TODO_REVERT:
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+ case TODO_EDIT:
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+ case TODO_REWORD:
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+ case TODO_FIXUP:
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+ case TODO_SQUASH:
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+ return 1;
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+ default:
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+ return 0;
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+ }
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+}
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+
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static int update_squash_messages(enum todo_command command,
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struct commit *commit, struct replay_opts *opts)
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{
@@ -1523,7 +1628,14 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
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return error(_("your index file is unmerged."));
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} else {
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unborn = get_oid("HEAD", &head);
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- if (unborn)
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+ /* Do we want to generate a root commit? */
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+ if (is_pick_or_similar(command) && opts->have_squash_onto &&
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+ !oidcmp(&head, &opts->squash_onto)) {
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+ if (is_fixup(command))
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+ return error(_("cannot fixup root commit"));
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+ flags |= CREATE_ROOT_COMMIT;
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+ unborn = 1;
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+ } else if (unborn)
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oidcpy(&head, the_hash_algo->empty_tree);
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if (index_differs_from(unborn ? EMPTY_TREE_SHA1_HEX : "HEAD",
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NULL, 0))
@@ -2136,6 +2248,12 @@ static int read_populate_opts(struct replay_opts *opts)
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read_strategy_opts(opts, &buf);
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strbuf_release(&buf);
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+ if (read_oneliner(&buf, rebase_path_squash_onto(), 0)) {
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+ if (get_oid_hex(buf.buf, &opts->squash_onto) < 0)
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+ return error(_("unusable squash-onto"));
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+ opts->have_squash_onto = 1;
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+ }
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+
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return 0;
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}
2259
sequencer.h
+4
@@ -44,6 +44,10 @@ struct replay_opts {
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char **xopts;
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size_t xopts_nr, xopts_alloc;
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+ /* placeholder commit for -i --root */
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+ struct object_id squash_onto;
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+ int have_squash_onto;
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+
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/* Only used by REPLAY_NONE */
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struct rev_info *revs;
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};