From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 6 Apr 2026 22:42:49 +0000 (-0700)
Subject: Merge branch 'tc/replay-down-to-root'
X-Git-Tag: v2.54.0-rc1~20
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=da54784d1cc3f4fdd90622fb9e3ae34a9e771702;p=thirdparty%2Fgit.git

Merge branch 'tc/replay-down-to-root'

git replay now supports replaying down to the root commit.

* tc/replay-down-to-root:
  replay: support replaying down from root commit
---

da54784d1cc3f4fdd90622fb9e3ae34a9e771702
diff --cc replay.c
index d7239d4c83,92f2279156..cf1f0bcba0
--- a/replay.c
+++ b/replay.c
@@@ -271,45 -228,33 +274,53 @@@ static struct commit *pick_regular_comm
  	struct commit *base, *replayed_base;
  	struct tree *pickme_tree, *base_tree, *replayed_base_tree;
  
- 	base = pickme->parents->item;
- 	replayed_base = mapped_commit(replayed_commits, base, onto);
+ 	if (pickme->parents) {
+ 		base = pickme->parents->item;
+ 		base_tree = repo_get_commit_tree(repo, base);
+ 	} else {
+ 		base = NULL;
+ 		base_tree = lookup_tree(repo, repo->hash_algo->empty_tree);
+ 	}
  
+ 	replayed_base = mapped_commit(replayed_commits, base, onto);
  	replayed_base_tree = repo_get_commit_tree(repo, replayed_base);
  	pickme_tree = repo_get_commit_tree(repo, pickme);
- 	base_tree = repo_get_commit_tree(repo, base);
  
 -	merge_opt->branch1 = short_commit_name(repo, replayed_base);
 -	merge_opt->branch2 = short_commit_name(repo, pickme);
 -	if (pickme->parents)
 -		merge_opt->ancestor = xstrfmt("parent of %s", merge_opt->branch2);
 -	else
 -		merge_opt->ancestor = xstrdup("empty tree");
 -
 -	merge_incore_nonrecursive(merge_opt,
 -				  base_tree,
 -				  replayed_base_tree,
 -				  pickme_tree,
 -				  result);
 -
 -	free((char*)merge_opt->ancestor);
 +	if (mode == REPLAY_MODE_PICK) {
 +		/* Cherry-pick: normal order */
 +		merge_opt->branch1 = short_commit_name(repo, replayed_base);
 +		merge_opt->branch2 = short_commit_name(repo, pickme);
- 		merge_opt->ancestor = xstrfmt("parent of %s", merge_opt->branch2);
++		if (pickme->parents)
++			merge_opt->ancestor = xstrfmt("parent of %s", merge_opt->branch2);
++		else
++			merge_opt->ancestor = xstrdup("empty tree");
 +
 +		merge_incore_nonrecursive(merge_opt,
 +					  base_tree,
 +					  replayed_base_tree,
 +					  pickme_tree,
 +					  result);
 +
 +		free((char *)merge_opt->ancestor);
 +	} else if (mode == REPLAY_MODE_REVERT) {
 +		/* Revert: swap base and pickme to reverse the diff */
 +		const char *pickme_name = short_commit_name(repo, pickme);
 +		merge_opt->branch1 = short_commit_name(repo, replayed_base);
 +		merge_opt->branch2 = xstrfmt("parent of %s", pickme_name);
 +		merge_opt->ancestor = pickme_name;
 +
 +		merge_incore_nonrecursive(merge_opt,
 +					  pickme_tree,
 +					  replayed_base_tree,
 +					  base_tree,
 +					  result);
 +
 +		free((char *)merge_opt->branch2);
 +	} else {
 +		BUG("unexpected replay mode %d", mode);
 +	}
  	merge_opt->ancestor = NULL;
 +	merge_opt->branch2 = NULL;
  	if (!result->clean)
  		return NULL;
  	/* Drop commits that become empty */
@@@ -358,14 -301,9 +369,12 @@@ int replay_revisions(struct rev_info *r
  	int ret;
  
  	advance = xstrdup_or_null(opts->advance);
 +	revert = xstrdup_or_null(opts->revert);
 +	if (revert)
 +		mode = REPLAY_MODE_REVERT;
  	set_up_replay_mode(revs->repo, &revs->cmdline, opts->onto,
 -			   &detached_head, &advance, &onto, &update_refs);
 +			   &detached_head, &advance, &revert, &onto, &update_refs);
  
- 	/* FIXME: Should allow replaying commits with the first as a root commit */
- 
  	if (prepare_revision_walk(revs) < 0) {
  		ret = error(_("error preparing revisions"));
  		goto out;