Merge pull request #2561 from jacquesg/merge-skip

No files merged may result in bogus merge conflict error

src/merge.c

@@ -2338,7 +2338,6 @@ done:
 
 static int merge_check_workdir(size_t *conflicts, git_repository *repo, git_index *index_new, git_vector *merged_paths)
 {
-	git_index *index_repo = NULL;
 	git_diff *wd_diff_list = NULL;
 	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
 	int error = 0;
@@ -2347,6 +2346,16 @@ static int merge_check_workdir(size_t *conflicts, git_repository *repo, git_inde
 
 	*conflicts = 0;
 
+	/* We need to have merged at least 1 file for the possibility to exist to
+	 * have conflicts with the workdir. Passing 0 as the pathspec count paramter
+	 * will consider all files in the working directory, that is, we may detect
+	 * a conflict if there were untracked files in the workdir prior to starting
+	 * the merge. This typically happens when cherry-picking a commmit whose
+	 * changes have already been applied.
+	 */
+	if (merged_paths->length == 0)
+		return 0;
+
 	opts.flags |= GIT_DIFF_INCLUDE_UNTRACKED;
 
 	/* Workdir changes may exist iff they do not conflict with changes that
@@ -2356,13 +2365,12 @@ static int merge_check_workdir(size_t *conflicts, git_repository *repo, git_inde
 	opts.pathspec.count = merged_paths->length;
 	opts.pathspec.strings = (char **)merged_paths->contents;
 
-	if ((error = git_diff_index_to_workdir(&wd_diff_list, repo, index_repo, &opts)) < 0)
+	if ((error = git_diff_index_to_workdir(&wd_diff_list, repo, NULL, &opts)) < 0)
 		goto done;
 
 	*conflicts = wd_diff_list->deltas.length;
 
 done:
-	git_index_free(index_repo);
 	git_diff_free(wd_diff_list);
 
 	return error;

tests/cherrypick/workdir.c

@@ -92,6 +92,47 @@ void test_cherrypick_workdir__automerge(void)
 	git_signature_free(signature);
 }
 
+/* git reset --hard cfc4f0999a8367568e049af4f72e452d40828a15
+ * git cherry-pick a43a050c588d4e92f11a6b139680923e9728477d*/
+void test_cherrypick_workdir__empty_result(void)
+{
+	git_oid head_oid;
+	git_signature *signature = NULL;
+	git_commit *head = NULL, *commit = NULL;
+	git_oid cherry_oid;
+
+	const char *cherrypick_oid = "a43a050c588d4e92f11a6b139680923e9728477d";
+
+	struct merge_index_entry merge_index_entries[] = {
+		{ 0100644, "19c5c7207054604b69c84d08a7571ef9672bb5c2", 0, "file1.txt" },
+		{ 0100644, "a58ca3fee5eb68b11adc2703e5843f968c9dad1e", 0, "file2.txt" },
+		{ 0100644, "28d9eb4208074ad1cc84e71ccc908b34573f05d2", 0, "file3.txt" },
+	};
+
+	cl_git_pass(git_signature_new(&signature, "Picker", "picker@example.org", time(NULL), 0));
+
+	git_oid_fromstr(&head_oid, "cfc4f0999a8367568e049af4f72e452d40828a15");
+
+	/* Create an untracked file that should not conflict */
+	cl_git_mkfile(TEST_REPO_PATH "/file4.txt", "");
+	cl_assert(git_path_exists(TEST_REPO_PATH "/file4.txt"));
+
+	cl_git_pass(git_commit_lookup(&head, repo, &head_oid));
+	cl_git_pass(git_reset(repo, (git_object *)head, GIT_RESET_HARD, NULL, NULL));
+
+	git_oid_fromstr(&cherry_oid, cherrypick_oid);
+	cl_git_pass(git_commit_lookup(&commit, repo, &cherry_oid));
+	cl_git_pass(git_cherrypick(repo, commit, NULL));
+
+	/* The resulting tree should not have changed, the change was already on HEAD */
+	cl_assert(merge_test_index(repo_index, merge_index_entries, 3));
+
+	git_commit_free(head);
+	git_commit_free(commit);
+
+	git_signature_free(signature);
+}
+
 /* git reset --hard bafbf6912c09505ac60575cd43d3f2aba3bd84d8
  * git cherry-pick e9b63f3655b2ad80c0ff587389b5a9589a3a7110
  */