Whitespace is ignored when calculating patch IDs. This is done by
removing all whitespace from diff lines before hashing them, including
a newline at the end of a file. If that newline is missing, however,
diff reports that fact in a separate line containing "\ No newline at
end of file\n", and this marker is hashed like a context line.
This goes against our goal of making patch IDs independent of
whitespace. Use the same heuristic that 2485eab55cc (git-patch-id: do
not trip over "no newline" markers, 2011-02-17) added to git patch-id
instead and skip diff lines that start with a backslash and a space
and are longer than twelve characters.
Reported-by: Tilman Vogel <tilman.vogel@xxxxxx>
Initial-test-by: Tilman Vogel <tilman.vogel@xxxxxx>
Signed-off-by: René Scharfe <l.s.r@xxxxxx>
---
diff.c | 2 ++
t/t3500-cherry.sh | 23 +++++++++++++++++++++++
2 files changed, 25 insertions(+)
diff --git a/diff.c b/diff.c
index f9709de7b45..f175019eb7a 100644
--- a/diff.c
+++ b/diff.c
@@ -6044,6 +6044,8 @@ static void patch_id_consume(void *priv, char *line, unsigned long len)
struct patch_id_t *data = priv;
int new_len;
+ if (len > 12 && starts_with(line, "\\ "))
+ return;
new_len = remove_space(line, len);
the_hash_algo->update_fn(data->ctx, line, new_len);
diff --git a/t/t3500-cherry.sh b/t/t3500-cherry.sh
index f038f34b7c0..2b8d9cb38ed 100755
--- a/t/t3500-cherry.sh
+++ b/t/t3500-cherry.sh
@@ -55,4 +55,27 @@ test_expect_success \
expr "$(echo $(git cherry master my-topic-branch) )" : "+ [^ ]* - .*"
'
+test_expect_success 'cherry ignores whitespace' '
+ git switch --orphan=upstream-with-space &&
+ test_commit initial file &&
+ >expect &&
+ git switch --create=feature-without-space &&
+
+ # A spaceless file on the feature branch. Expect a match upstream.
+ printf space >file &&
+ git add file &&
+ git commit -m"file without space" &&
+ git log --format="- %H" -1 >>expect &&
+
+ # A further change. Should not match upstream.
+ test_commit change file &&
+ git log --format="+ %H" -1 >>expect &&
+
+ git switch upstream-with-space &&
+ # Same as the spaceless file, just with spaces and on upstream.
+ test_commit "file with space" file "s p a c e" file-with-space &&
+ git cherry upstream-with-space feature-without-space >actual &&
+ test_cmp expect actual
+'
+
test_done
--
2.28.0
