builtin add -p: fix hunk splitting

Thanks to Junio and Ævar for their comments on V1. I've updated the commit message and added a helper function as suggested.

V1 Cover Letter: Fix a small regression in the hunk splitting of the builtin version compared to the perl version. Thanks to Szeder for the easy to follow bug report.

Phillip Wood (2):
t3701: clean up hunk splitting tests
builtin add -p: fix hunk splitting

 add-patch.c                | 20 ++++++++++------
 t/t3701-add-interactive.sh | 48 ++++++++++++++++++++++++++++++++++----
 2 files changed, 56 insertions(+), 12 deletions(-)

base-commit: cd3e606211bb1cf8bc57f7d76bab98cc17a150bc
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1100%2Fphillipwood%2Fwip%2Fadd-p-fix-hunk-splitting-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1100/phillipwood/wip/add-p-fix-hunk-splitting-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/1100

Range-diff vs v1:

 1:  cc8639fc29d = 1:  cc8639fc29d t3701: clean up hunk splitting tests
 2:  5d5639c2b04 ! 2:  b698989e265 builtin add -p: fix hunk splitting

@@ Metadata
## Commit message ##
builtin add -p: fix hunk splitting

+ The C reimplementation of "add -p" fails to split the last hunk in a
+ file if hunk ends with an addition or deletion without any post context
+ line unless it is the last file to be processed.
+
To determine whether a hunk can be split a counter is incremented each time a context line follows an insertion or deletion. If at the end of the hunk the value of this counter is greater than one then the hunk
@@ Commit message

## add-patch.c ##
+@@ add-patch.c: static int is_octal(const char *p, size_t len)
+ return 1;
+ }
+
++static void complete_file(char marker, struct hunk *hunk)
++{
++ if (marker == '-' || marker == '+')
++ /*
++ * Last hunk ended in non-context line (i.e. it
++ * appended lines to the file, so there are no
++ * trailing context lines).
++ */
++ hunk->splittable_into++;
++}
++
+ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
+ {
+ struct strvec args = STRVEC_INIT;
@@ add-patch.c: static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
eol = pend;

if (starts_with(p, "diff ")) {
-+ if (marker == '-' || marker == '+')
-+ /*
-+ * Last hunk ended in non-context line (i.e. it
-+ * appended lines to the file, so there are no
-+ * trailing context lines).
-+ */
-+ hunk->splittable_into++;
++ complete_file(marker, hunk);
ALLOC_GROW_BY(s->file_diff, s->file_diff_nr, 1,
file_diff_alloc);
file_diff = s->file_diff + s->file_diff_nr - 1;
+@@ add-patch.c: static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
+ file_diff->hunk->colored_end = hunk->colored_end;
+ }
+ }
+-
+- if (marker == '-' || marker == '+')
+- /*
+- * Last hunk ended in non-context line (i.e. it appended lines
+- * to the file, so there are no trailing context lines).
+- */
+- hunk->splittable_into++;
++ complete_file(marker, hunk);
+
+ /* non-colored shorter than colored? */
+ if (colored_p != colored_pend) {

## t/t3701-add-interactive.sh ##
@@ t/t3701-add-interactive.sh: test_expect_success 'correct message when there is nothing to do' '

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