[PATCH 3/3] apply: omit ws check for excluded paths

[Junio C Hamano <gitster@pobox.com>]

Whitespace breakages are checked while the patch is being parsed.
Disable them at the beginning of parse_chunk(), where each
individual patch is parsed, immediately after we learn what path the
patch applies to and before we start parsing the changes.

One may naively think we should be able to not just skip the
whitespace checks but simply fast-forward to the next patch without
doing anything once use_patch() tells us that this patch is not
going to be used.  But in reality we cannot really skip much of the
parsing, primarily because parsing "@@ -k,l +m,n @@" lines and
counting the input lines is how we determine the boundaries of
individual patches.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

 builtin/apply.c          |  9 ++++++---
 t/t4124-apply-ws-rule.sh | 11 +++++++++++
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/builtin/apply.c b/builtin/apply.c
index bf075cc..13319e8 100644
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -1997,9 +1997,12 @@ static int parse_chunk(char *buffer, unsigned long size, struct patch *patch)
 
 	prefix_patch(patch);
 
-	patch->ws_rule = whitespace_rule(patch->new_name
-					 ? patch->new_name
-					 : patch->old_name);
+	if (!use_patch(patch))
+		patch->ws_rule = 0;
+	else
+		patch->ws_rule = whitespace_rule(patch->new_name
+						 ? patch->new_name
+						 : patch->old_name);
 
 	patchsize = parse_single_patch(buffer + offset + hdrsize,
 				       size - offset - hdrsize, patch);
diff --git a/t/t4124-apply-ws-rule.sh b/t/t4124-apply-ws-rule.sh
index 5d0c598..c6474de 100755
--- a/t/t4124-apply-ws-rule.sh
+++ b/t/t4124-apply-ws-rule.sh
@@ -512,4 +512,15 @@ test_expect_success 'whitespace=fix to expand' '
 	git -c core.whitespace=tab-in-indent apply --whitespace=fix patch
 '
 
+test_expect_success 'whitespace check skipped for excluded paths' '
+	git config core.whitespace blank-at-eol &&
+	>used &&
+	>unused &&
+	git add used unused &&
+	echo "used" >used &&
+	echo "unused " >unused &&
+	git diff-files -p used unused >patch &&
+	git apply --include=used --stat --whitespace=error <patch
+'
+
 test_done
-- 
2.1.0-rc1-209-g4e1b551