[PATCH 3/6] apply: fix adding new files on i-t-a entries

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

Suppose that you came up with some contents to register at path F in
your working tree, told Git about your intention with "add -N F", and
then tried to apply a patch that wants to _create_ F:

Without this patch, we would say "F already exists so a patch to
create is incompatible with our current state".

With this patch, i-t-a entries are ignored and we do not say that, but
instead we'll hopefully trigger "does it exist in the working tree"
check, unless you are running under "--cached".

Which means that this change will not lead to data loss in the
"untracked" file F in the working tree that was merely added to the
index with i-t-a bit.

(commit message mostly from Junio)

Reported-by: Patrick Higgins <phiggins@google.com>
Reported-by: Bjørnar Snoksrud <snoksrud@gmail.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 builtin/apply.c       |  9 +++++----
 t/t2203-add-intent.sh | 13 +++++++++++++
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/builtin/apply.c b/builtin/apply.c
index 0769b09..315fce8 100644
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -3550,10 +3550,11 @@ static int check_to_create(const char *new_name, int ok_if_exists)
 {
 	struct stat nst;
 
-	if (check_index &&
-	    cache_name_pos(new_name, strlen(new_name)) >= 0 &&
-	    !ok_if_exists)
-		return EXISTS_IN_INDEX;
+	if (check_index && !ok_if_exists) {
+		int pos = cache_name_pos(new_name, strlen(new_name));
+		if (pos >= 0 && !ce_intent_to_add(active_cache[pos]))
+			return EXISTS_IN_INDEX;
+	}
 	if (cached)
 		return 0;
 
diff --git a/t/t2203-add-intent.sh b/t/t2203-add-intent.sh
index 2a4a749..bb5ef2b 100755
--- a/t/t2203-add-intent.sh
+++ b/t/t2203-add-intent.sh
@@ -82,5 +82,18 @@ test_expect_success 'cache-tree invalidates i-t-a paths' '
 	test_cmp expect actual
 '
 
+test_expect_success 'apply adds new file on i-t-a entry' '
+	git init apply &&
+	(
+		cd apply &&
+		echo newcontent >newfile &&
+		git add newfile &&
+		git diff --cached >patch &&
+		rm .git/index &&
+		git add -N newfile &&
+		git apply --cached patch
+	)
+'
+
 test_done
 
-- 
2.3.0.rc1.137.g477eb31