Merge branch 'en/ort-dir-rename-and-symlink-fix'

Merging a branch with directory renames into a branch that changes
the directory to a symlink was mishandled by the ort merge
strategy, which has been corrected.

* en/ort-dir-rename-and-symlink-fix:
  merge-ort: fix bug with dir rename vs change dir to symlink

Author: ttaylorr

merge-ort.c

@@ -2619,8 +2619,40 @@ static void apply_directory_rename_modifications(struct merge_options *opt,
 	}
 
 	assert(ci->filemask == 2 || ci->filemask == 4);
-	assert(ci->dirmask == 0);
-	strmap_remove(&opt->priv->paths, old_path, 0);
+	assert(ci->dirmask == 0 || ci->dirmask == 1);
+	if (ci->dirmask == 0)
+		strmap_remove(&opt->priv->paths, old_path, 0);
+	else {
+		/*
+		 * This file exists on one side, but we still had a directory
+		 * at the old location that we can't remove until after
+		 * processing all paths below it.  So, make a copy of ci in
+		 * new_ci and only put the file information into it.
+		 */
+		new_ci = mem_pool_calloc(&opt->priv->pool, 1, sizeof(*new_ci));
+		memcpy(new_ci, ci, sizeof(*ci));
+		assert(!new_ci->match_mask);
+		new_ci->dirmask = 0;
+		new_ci->stages[1].mode = 0;
+		oidcpy(&new_ci->stages[1].oid, null_oid());
+
+		/*
+		 * Now that we have the file information in new_ci, make sure
+		 * ci only has the directory information.
+		 */
+		ci->filemask = 0;
+		ci->merged.clean = 1;
+		for (i = MERGE_BASE; i <= MERGE_SIDE2; i++) {
+			if (ci->dirmask & (1 << i))
+				continue;
+			/* zero out any entries related to files */
+			ci->stages[i].mode = 0;
+			oidcpy(&ci->stages[i].oid, null_oid());
+		}
+
+		// Now we want to focus on new_ci, so reassign ci to it
+		ci = new_ci;
+	}
 
 	branch_with_new_path   = (ci->filemask == 2) ? opt->branch1 : opt->branch2;
 	branch_with_dir_rename = (ci->filemask == 2) ? opt->branch2 : opt->branch1;

t/t6423-merge-rename-directories.sh

@@ -5304,6 +5304,62 @@ test_expect_merge_algorithm failure success '12l (A into B): Rename into each ot
 	)
 '
 
+# Testcase 12m, Directory rename, plus change of parent dir to symlink
+#   Commit O:  dir/subdir/file
+#   Commit A:  renamed-dir/subdir/file
+#   Commit B:  dir/subdir
+#   In words:
+#     A: dir/subdir/ -> renamed-dir/subdir
+#     B: delete dir/subdir/file, add dir/subdir as symlink
+#
+#   Expected: CONFLICT (rename/delete): renamed-dir/subdir/file,
+#             CONFLICT (file location): renamed-dir/subdir vs. dir/subdir
+#             CONFLICT (directory/file): renamed-dir/subdir symlink has
+#                                        renamed-dir/subdir in the way
+
+test_setup_12m () {
+	git init 12m &&
+	(
+		cd 12m &&
+
+		mkdir -p dir/subdir &&
+		echo 1 >dir/subdir/file &&
+		git add . &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git switch A &&
+		git mv dir/ renamed-dir/ &&
+		git add . &&
+		git commit -m "A" &&
+
+		git switch B &&
+		git rm dir/subdir/file &&
+		mkdir dir &&
+		ln -s /dev/null dir/subdir &&
+		git add . &&
+		git commit -m "B"
+	)
+}
+
+test_expect_merge_algorithm failure success '12m: Change parent of renamed-dir to symlink on other side' '
+	test_setup_12m &&
+	(
+		cd 12m &&
+
+		git checkout -q A^0 &&
+
+		test_must_fail git -c merge.directoryRenames=conflict merge -s recursive B^0 &&
+
+		test_stdout_line_count = 3 git ls-files -s &&
+		test_stdout_line_count = 2 ls -1 renamed-dir &&
+		test_path_is_missing dir
+	)
+'
+
 ###########################################################################
 # SECTION 13: Checking informational and conflict messages
 #