rebase: skip branch symref aliases

rebase --update-refs records local branch decorations before replaying
commits. If a decoration is a symbolic branch such as refs/heads/main
pointing at refs/heads/master, updating it later dereferences back to
master and can fail because the normal rebase path already moved that
branch.

Resolve local branch symref decorations to their referents before
queuing update-ref commands, and skip duplicates. This keeps branch
aliases from scheduling a second update for the same underlying branch
while still using the existing old-OID check for the single queued
update.

Signed-off-by: Son Luong Ngoc <sluongng@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/sequencer.c b/sequencer.c
index 1ee4b2875b25a08f6589314aae11ab5e3f35eecc..4a83d1337c6aa87798bdc4f402c88fa53108dbac 100644 (file)
--- a/sequencer.c
+++ b/sequencer.c
@@ -6445,15 +6445,22 @@ static int add_decorations_to_list(const struct commit *commit,
                                   struct todo_add_branch_context *ctx)
 {
        const struct name_decoration *decoration = get_name_decoration(&commit->object);
-       const char *head_ref = refs_resolve_ref_unsafe(get_main_ref_store(the_repository),
-                                                      "HEAD",
+       struct ref_store *refs = get_main_ref_store(the_repository);
+       const char *head_ref = refs_resolve_ref_unsafe(refs, "HEAD",
                                                       RESOLVE_REF_READING,
-                                                      NULL,
-                                                      NULL);
+                                                      NULL, NULL);
+       char *resolved_head_ref = refs_resolve_refdup(refs, "HEAD",
+                                                      RESOLVE_REF_READING,
+                                                      NULL, NULL);
+       struct strbuf update_ref = STRBUF_INIT;
 
        while (decoration) {
                struct todo_item *item;
                const char *path;
+               const char *ref = decoration->name;
+               const char *resolved_ref;
+               int is_symref = 0;
+               int flags = 0;
                size_t base_offset = ctx->buf->len;
 
                /*
@@ -6461,12 +6468,44 @@ static int add_decorations_to_list(const struct commit *commit,
                 * updated by the default rebase behavior.
                 * Exclude it from the list of refs to update,
                 * as well as any non-branch decorations.
+                *
+                * Resolve branch symrefs after checking for the current HEAD so
+                * that aliases do not schedule duplicate updates for their
+                * referents.
+                *
                 * Non-branch decorations may be present if the pretty format
                 * includes "%d", which would have loaded all refs
                 * into the global decoration table.
                 */
-               if ((head_ref && !strcmp(head_ref, decoration->name)) ||
-                   (decoration->type != DECORATION_REF_LOCAL)) {
+               if (decoration->type != DECORATION_REF_LOCAL) {
+                       decoration = decoration->next;
+                       continue;
+               }
+
+               if (head_ref && !strcmp(head_ref, ref)) {
+                       decoration = decoration->next;
+                       continue;
+               }
+
+               strbuf_reset(&update_ref);
+               resolved_ref = refs_resolve_ref_unsafe(refs, ref,
+                                                      RESOLVE_REF_READING |
+                                                      RESOLVE_REF_NO_RECURSE,
+                                                      NULL, &flags);
+               if ((flags & REF_ISSYMREF) && resolved_ref) {
+                       if (!starts_with(resolved_ref, "refs/heads/")) {
+                               decoration = decoration->next;
+                               continue;
+                       }
+
+                       strbuf_addstr(&update_ref, resolved_ref);
+                       ref = update_ref.buf;
+                       is_symref = 1;
+               }
+
+               if ((is_symref && resolved_head_ref &&
+                    !strcmp(resolved_head_ref, ref)) ||
+                   string_list_has_string(&ctx->refs_to_oids, ref)) {
                        decoration = decoration->next;
                        continue;
                }
@@ -6478,19 +6517,19 @@ static int add_decorations_to_list(const struct commit *commit,
                memset(item, 0, sizeof(*item));
 
                /* If the branch is checked out, then leave a comment instead. */
-               if ((path = branch_checked_out(decoration->name))) {
+               if ((path = branch_checked_out(ref))) {
                        item->command = TODO_COMMENT;
                        strbuf_commented_addf(ctx->buf, comment_line_str,
                                              "Ref %s checked out at '%s'\n",
-                                             decoration->name, path);
+                                             ref, path);
                } else {
                        struct string_list_item *sti;
                        item->command = TODO_UPDATE_REF;
-                       strbuf_addf(ctx->buf, "%s\n", decoration->name);
+                       strbuf_addf(ctx->buf, "%s\n", ref);
 
                        sti = string_list_insert(&ctx->refs_to_oids,
-                                                decoration->name);
-                       sti->util = init_update_ref_record(decoration->name);
+                                                ref);
+                       sti->util = init_update_ref_record(ref);
                }
 
                item->offset_in_buf = base_offset;
@@ -6501,6 +6540,8 @@ static int add_decorations_to_list(const struct commit *commit,
                decoration = decoration->next;
        }
 
+       strbuf_release(&update_ref);
+       free(resolved_head_ref);
        return 0;
 }
 

diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 42ba8cc313e576a1ae7298c0a9668612528cf360..29447c0fc307acc94d66dedbd3c61cfe1532230d 100755 (executable)
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -1978,7 +1978,7 @@ test_expect_success '--update-refs ignores non-branch decorations' '
        test_cmp expect actual
 '
 
-test_expect_failure '--update-refs skips branch symrefs to current branch' '
+test_expect_success '--update-refs skips branch symrefs to current branch' '
        test_when_finished "
                test_might_fail git rebase --abort &&
                git checkout primary &&