Merge branch 'rp/apply-intent-to-add-fix'

"git apply -N" should start from the current index and register
only new files, but it instead started from an empty index, which
has been corrected.

* rp/apply-intent-to-add-fix:
  apply docs: clarify wording for --intent-to-add
  t4140: test apply --intent-to-add interactions
  apply: only write intents to add for new files
  apply: read in the index in --intent-to-add mode

3 files changed, 37 insertions, 7 deletions

diff --git a/Documentation/git-apply.adoc b/Documentation/git-apply.adoc
index 952518b8af..6c71ee69da 100644
--- a/Documentation/git-apply.adoc
+++ b/Documentation/git-apply.adoc
@@ -75,13 +75,14 @@ OPTIONS
 	tree. If `--check` is in effect, merely check that it would
 	apply cleanly to the index entry.
 
+-N::
 --intent-to-add::
 	When applying the patch only to the working tree, mark new
 	files to be added to the index later (see `--intent-to-add`
-	option in linkgit:git-add[1]). This option is ignored unless
-	running in a Git repository and `--index` is not specified.
-	Note that `--index` could be implied by other options such
-	as `--cached` or `--3way`.
+	option in linkgit:git-add[1]). This option is ignored if
+	`--index` or `--cached` are used, and has no effect outside a Git
+	repository. Note that `--index` could be implied by other options
+	such as `--3way`.
 
 -3::
 --3way::
diff --git a/apply.c b/apply.c
index 8bbe6ed224..8637ad4c9f 100644
--- a/apply.c
+++ b/apply.c
@@ -4565,7 +4565,7 @@ static int create_file(struct apply_state *state, struct patch *patch)
 
 	if (patch->conflicted_threeway)
 		return add_conflicted_stages_file(state, patch);
-	else if (state->update_index)
+	else if (state->check_index || (state->ita_only && patch->is_new > 0))
 		return add_index_file(state, path, mode, buf, size);
 	return 0;
 }
@@ -4833,7 +4833,7 @@ static int apply_patch(struct apply_state *state,
 					       LOCK_DIE_ON_ERROR);
 	}
 
-	if (state->check_index && read_apply_cache(state) < 0) {
+	if ((state->check_index || state->update_index) && read_apply_cache(state) < 0) {
 		error(_("unable to read index file"));
 		res = -128;
 		goto end;
diff --git a/t/t4140-apply-ita.sh b/t/t4140-apply-ita.sh
index c614eaf04c..0b11a8aef4 100755
--- a/t/t4140-apply-ita.sh
+++ b/t/t4140-apply-ita.sh
@@ -7,6 +7,10 @@ test_description='git apply of i-t-a file'
 test_expect_success setup '
 	test_write_lines 1 2 3 4 5 >blueprint &&
 
+	cat blueprint >committed-file &&
+	git add committed-file &&
+	git commit -m "commit" &&
+
 	cat blueprint >test-file &&
 	git add -N test-file &&
 	git diff >creation-patch &&
@@ -14,7 +18,14 @@ test_expect_success setup '
 
 	rm -f test-file &&
 	git diff >deletion-patch &&
-	grep "deleted file mode 100644" deletion-patch
+	grep "deleted file mode 100644" deletion-patch &&
+
+	git rm -f test-file &&
+	test_write_lines 6 >>committed-file &&
+	cat blueprint >test-file &&
+	git add -N test-file &&
+	git diff >complex-patch &&
+	git restore committed-file
 '
 
 test_expect_success 'apply creation patch to ita path (--cached)' '
@@ -53,4 +64,22 @@ test_expect_success 'apply deletion patch to ita path (--index)' '
 	git ls-files --stage --error-unmatch test-file
 '
 
+test_expect_success 'apply creation patch to existing index with -N' '
+	git rm -f test-file &&
+	cat blueprint >index-file &&
+	git add index-file &&
+	git apply -N creation-patch &&
+
+	git ls-files --stage --error-unmatch index-file &&
+	git ls-files --stage --error-unmatch test-file
+'
+
+test_expect_success 'apply complex patch with -N' '
+	git rm -f test-file index-file &&
+	git apply -N complex-patch &&
+
+	git ls-files --stage --error-unmatch test-file &&
+	git diff | grep "a/committed-file"
+'
+
 test_done