Re: [PATCH 08/11] merge-ort: implement CE_SKIP_WORKTREE handling with conflicted entries

From: Elijah Newren <redacted>

When merge conflicts occur in paths removed by a sparse-checkout, we
need to unsparsify those paths (clear the SKIP_WORKTREE bit), and write
out the conflicted file to the working copy.  In the very unlikely case
that someone manually put a file into the working copy at the location
of the SKIP_WORKTREE file, we need to avoid overwriting whatever edits
they have made and move that file to a different location first.

Signed-off-by: Elijah Newren <redacted>
---
 merge-ort.c                       | 43 +++++++++++++++++++++----------
 t/t6428-merge-conflicts-sparse.sh |  4 +--
 2 files changed, 32 insertions(+), 15 deletions(-)

diff --git a/merge-ort.c b/merge-ort.c
index a998f843a1da..37b69cbe0f9a 100644
--- a/merge-ort.c
+++ b/merge-ort.c

@@ -3235,23 +3235,27 @@ static int checkout(struct merge_options *opt,
 	return ret;
 }
 
-static int record_conflicted_index_entries(struct merge_options *opt,
-					   struct index_state *index,
-					   struct strmap *paths,
-					   struct strmap *conflicted)
+static int record_conflicted_index_entries(struct merge_options *opt)
 {
 	struct hashmap_iter iter;
 	struct strmap_entry *e;
+	struct index_state *index = opt->repo->index;
+	struct checkout state = CHECKOUT_INIT;
 	int errs = 0;
 	int original_cache_nr;
 
-	if (strmap_empty(conflicted))
+	if (strmap_empty(&opt->priv->conflicted))
 		return 0;
 
+	/* If any entries have skip_worktree set, we'll have to check 'em out */
+	state.force = 1;
+	state.quiet = 1;
+	state.refresh_cache = 1;
+	state.istate = index;
 	original_cache_nr = index->cache_nr;
 
 	/* Put every entry from paths into plist, then sort */
-	strmap_for_each_entry(conflicted, &iter, e) {
+	strmap_for_each_entry(&opt->priv->conflicted, &iter, e) {
 		const char *path = e->key;
 		struct conflict_info *ci = e->value;
 		int pos;

@@ -3292,9 +3296,23 @@ static int record_conflicted_index_entries(struct merge_options *opt,
 			 * the higher order stages.  Thus, we need override
 			 * the CE_SKIP_WORKTREE bit and manually write those
 			 * files to the working disk here.
-			 *
-			 * TODO: Implement this CE_SKIP_WORKTREE fixup.
 			 */
+			if (ce_skip_worktree(ce)) {
+				struct stat st;
+
+				if (!lstat(path, &st)) {
+					char *new_name = unique_path(&opt->priv->paths,
+								     path,
+								     "cruft");
+
+					path_msg(opt, path, 1,
+						 _("Note: %s not up to date and in way of checking out conflicted version; old copy renamed to %s"),
+						 path, new_name);