Merge branch 'jc/fix-add-u-unmerged' into maint

* jc/fix-add-u-unmerged:
  Fix "add -u" that sometimes fails to resolve unmerged paths

Conflicts:
	builtin/add.c

builtin/add.c

@@ -26,6 +26,27 @@ struct update_callback_data {
 	int add_errors;
 };
 
+static int fix_unmerged_status(struct diff_filepair *p,
+			       struct update_callback_data *data)
+{
+	if (p->status != DIFF_STATUS_UNMERGED)
+		return p->status;
+	if (!(data->flags & ADD_CACHE_IGNORE_REMOVAL) && !p->two->mode)
+		/*
+		 * This is not an explicit add request, and the
+		 * path is missing from the working tree (deleted)
+		 */
+		return DIFF_STATUS_DELETED;
+	else
+		/*
+		 * Either an explicit add request, or path exists
+		 * in the working tree.  An attempt to explicitly
+		 * add a path that does not exist in the working tree
+		 * will be caught as an error by the caller immediately.
+		 */
+		return DIFF_STATUS_MODIFIED;
+}
+
 static void update_callback(struct diff_queue_struct *q,
 			    struct diff_options *opt, void *cbdata)
 {
@@ -35,30 +56,9 @@ static void update_callback(struct diff_queue_struct *q,
 	for (i = 0; i < q->nr; i++) {
 		struct diff_filepair *p = q->queue[i];
 		const char *path = p->one->path;
-		switch (p->status) {
+		switch (fix_unmerged_status(p, data)) {
 		default:
 			die(_("unexpected diff status %c"), p->status);
-		case DIFF_STATUS_UNMERGED:
-			/*
-			 * ADD_CACHE_IGNORE_REMOVAL is unset if "git
-			 * add -u" is calling us, In such a case, a
-			 * missing work tree file needs to be removed
-			 * if there is an unmerged entry at stage #2,
-			 * but such a diff record is followed by
-			 * another with DIFF_STATUS_DELETED (and if
-			 * there is no stage #2, we won't see DELETED
-			 * nor MODIFIED).  We can simply continue
-			 * either way.
-			 */
-			if (!(data->flags & ADD_CACHE_IGNORE_REMOVAL))
-				continue;
-			/*
-			 * Otherwise, it is "git add path" is asking
-			 * to explicitly add it; we fall through.  A
-			 * missing work tree file is an error and is
-			 * caught by add_file_to_index() in such a
-			 * case.
-			 */
 		case DIFF_STATUS_MODIFIED:
 		case DIFF_STATUS_TYPE_CHANGED:
 			if (add_file_to_index(&the_index, path, data->flags)) {
@@ -91,6 +91,7 @@ int add_files_to_cache(const char *prefix, const char **pathspec, int flags)
 	data.flags = flags;
 	data.add_errors = 0;
 	rev.diffopt.format_callback_data = &data;
+	rev.max_count = 0; /* do not compare unmerged paths with stage #2 */
 	run_diff_files(&rev, DIFF_RACY_IS_MODIFIED);
 	return !!data.add_errors;
 }

t/t2200-add-update.sh

@@ -149,31 +149,21 @@ test_expect_success 'add -u resolves unmerged paths' '
 	echo 3 >path1 &&
 	echo 2 >path3 &&
 	echo 2 >path5 &&
+
+	# Explicit resolving by adding removed paths should fail
+	test_must_fail git add path4 &&
+	test_must_fail git add path6 &&
+
+	# "add -u" should notice removals no matter what stages
+	# the index entries are in.
 	git add -u &&
 	git ls-files -s path1 path2 path3 path4 path5 path6 >actual &&
-	{
-		echo "100644 $three 0	path1"
-		echo "100644 $one 1	path3"
-		echo "100644 $one 1	path4"
-		echo "100644 $one 3	path5"
-		echo "100644 $one 3	path6"
-	} >expect &&
-	test_cmp expect actual &&
-
-	# Bonus tests.  Explicit resolving
-	git add path3 path5 &&
-	test_must_fail git add path4 &&
-	test_must_fail git add path6 &&
-	git rm path4 &&
-	git rm path6 &&
-
-	git ls-files -s "path?" >actual &&
 	{
 		echo "100644 $three 0	path1"
 		echo "100644 $two 0	path3"
 		echo "100644 $two 0	path5"
-	} >expect
+	} >expect &&
-
+	test_cmp expect actual
 '
 
 test_expect_success '"add -u non-existent" should fail' '