[PATCH 2/9] apply --whitespace=fix: detect new blank lines at eof correctly

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

The command tries to strip blank lines at the end of the file added by a
patch.  However, if the original ends with blank lines, often the patch
hunk ends like this:

    @@ -l,5 +m,7 @@$
    _context$
    _context$
    -deleted$
    +$
    +$
    +$
    _$
    _$

where _ stands for SP and $ shows a end-of-line.  This example patch adds
three trailing blank lines, but the code fails to notice it, because it
only pays attention to added blank lines at the very end of the hunk.  In
this example, the three added blank lines do not appear textually at the
end in the patch, even though you can see that they are indeed added at
the end, if you rearrange the diff like this:

    @@ -l,5 +m,7 @@$
    _context$
    _context$
    -deleted$
    _$
    _$
    +$
    +$
    +$

Fix this by not resetting the number of (candidate) added blank lines at
the end when the loop sees a context line that is empty.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin-apply.c          |    6 ++++++
 t/t4124-apply-ws-rule.sh |   12 ++++++++++++
 2 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/builtin-apply.c b/builtin-apply.c
index 5b5bde4..c5e4048 100644
--- a/builtin-apply.c
+++ b/builtin-apply.c
@@ -1913,6 +1913,7 @@ static int apply_one_fragment(struct image *img, struct fragment *frag,
 		int len = linelen(patch, size);
 		int plen, added;
 		int added_blank_line = 0;
+		int is_blank_context = 0;
 
 		if (!len)
 			break;
@@ -1945,8 +1946,11 @@ static int apply_one_fragment(struct image *img, struct fragment *frag,
 			*new++ = '\n';
 			add_line_info(&preimage, "\n", 1, LINE_COMMON);
 			add_line_info(&postimage, "\n", 1, LINE_COMMON);
+			is_blank_context = 1;
 			break;
 		case ' ':
+			if (plen && patch[1] == '\n')
+				is_blank_context = 1;
 		case '-':
 			memcpy(old, patch + 1, plen);
 			add_line_info(&preimage, old, plen,
@@ -1986,6 +1990,8 @@ static int apply_one_fragment(struct image *img, struct fragment *frag,
 		}
 		if (added_blank_line)
 			new_blank_lines_at_end++;
+		else if (is_blank_context)
+			;
 		else
 			new_blank_lines_at_end = 0;
 		patch += len;
diff --git a/t/t4124-apply-ws-rule.sh b/t/t4124-apply-ws-rule.sh
index 6898722..ba2b7f9 100755
--- a/t/t4124-apply-ws-rule.sh
+++ b/t/t4124-apply-ws-rule.sh
@@ -177,4 +177,16 @@ test_expect_success 'blank at EOF with --whitespace=fix (2)' '
 	test_cmp expect one
 '
 
+test_expect_success 'blank at EOF with --whitespace=fix (3)' '
+	{ echo a; echo b; echo; } >one &&
+	git add one &&
+	{ echo a; echo c; echo; } >expect &&
+	{ cat expect; echo; echo; } >one &&
+	git diff -- one >patch &&
+
+	git checkout one &&
+	git apply --whitespace=fix patch &&
+	test_cmp expect one
+'
+
 test_done
-- 
1.6.4.2.313.g0425f