[PATCH 1/1] git-apply: Allow simultaneous --cached and --3way options

[Jerry Zhang <jerry@skydio.com>]

Previously, --cached and --3way were not
allowed to be used together, since --3way
wrote conflict markers into the working tree.

These changes change semantics so that if
these flags are given together and there is
a conflict, the conflict markers are added
directly to cache. If there is no conflict,
the patch is applied directly to cache as
expected.

Signed-off-by: Jerry Zhang <jerry@skydio.com>
Signed-off-by: Jerry Zhang <jerryxzha@googlemail.com>
---
 Documentation/git-apply.txt |  4 +++-
 apply.c                     | 13 +++++++------
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/Documentation/git-apply.txt b/Documentation/git-apply.txt
index 91d9a8601c..3dc0085066 100644
--- a/Documentation/git-apply.txt
+++ b/Documentation/git-apply.txt
@@ -89,7 +89,9 @@ OPTIONS
 	and we have those blobs available locally, possibly leaving the
 	conflict markers in the files in the working tree for the user to
 	resolve.  This option implies the `--index` option, and is incompatible
-	with the `--reject` and the `--cached` options.
+	with the `--reject` option. When used with the --cached option, any
+	conflict markers are added directly to the cache rather than the
+	working tree.
 
 --build-fake-ancestor=<file>::
 	Newer 'git diff' output has embedded 'index information'
diff --git a/apply.c b/apply.c
index 6695a931e9..fc94ca0e99 100644
--- a/apply.c
+++ b/apply.c
@@ -133,8 +133,6 @@ int check_apply_state(struct apply_state *state, int force_apply)
 
 	if (state->apply_with_reject && state->threeway)
 		return error(_("--reject and --3way cannot be used together."));
-	if (state->cached && state->threeway)
-		return error(_("--cached and --3way cannot be used together."));
 	if (state->threeway) {
 		if (is_not_gitdir)
 			return error(_("--3way outside a repository"));
@@ -4490,13 +4488,16 @@ static int create_file(struct apply_state *state, struct patch *patch)
 
 	if (!mode)
 		mode = S_IFREG | 0644;
-	if (create_one_file(state, path, mode, buf, size))
-		return -1;
+	if (!state->cached) {
+		if (create_one_file(state, path, mode, buf, size))
+			return -1;
+	}
 
-	if (patch->conflicted_threeway)
+	if (patch->conflicted_threeway && !state->cached)
 		return add_conflicted_stages_file(state, patch);
-	else if (state->update_index)
+	else if (state->update_index) {
 		return add_index_file(state, path, mode, buf, size);
+	}
 	return 0;
 }
 
-- 
2.29.0