Allow "no-op hunks" when editing the diff in git add -e

I use git add -e frequently. Often there are multiple hunks and I end up deleting the + lines and converting the - lines to context lines, as I like to stage massive changes in an incremental fashion (and commit those staged changes incrementally, too).

Some time after I invented git add -e, this feature was broken, and I had to start identifying and deleting those hunks with no changes.

I finally got around to find the regression, and to fix it. Here is the outcome of this effort.

Johannes Schindelin (1):
apply --recount: allow "no-op hunks"

 apply.c                |  2 +-
 t/t4136-apply-check.sh | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

base-commit: 8858448bb49332d353febc078ce4a3abcc962efe
Published-As: https://github.com/gitgitgadget/git/releases/tags/pr-74%2Fdscho%2Fapply-recount-empty-hunk-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-74/dscho/apply-recount-empty-hunk-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/74

gitgitgadget

From: Johannes Schindelin <[email protected]>

When editing patches e.g. in git add -e, it is quite common that a hunk ends up having no -/+ lines, i.e. it is now supposed to do nothing.

This use case was broken by ad6e8ed37bc1 (apply: reject a hunk that does not do anything, 2015-06-01) with the good intention of catching a very real, different issue in hand-edited patches.

So let's use the --recount option as the tell-tale whether the user would actually be okay with no-op hunks.

Add a test case to make sure that this use case does not regress again.

---
 apply.c                |  2 +-
 t/t4136-apply-check.sh | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

index 073d5f0451..76955afb00 100644
@@ -1748,7 +1748,7 @@ static int parse_fragment(struct apply_state *state,
 	}
 	if (oldlines || newlines)
 		return -1;
-	if (!deleted && !added)
+	if (!patch->recount && !deleted && !added)
 		return -1;
 
 	fragment->leading = leading;

index 6d92872318..4c3f264a63 100755
@@ -29,6 +29,18 @@ test_expect_success 'apply exits non-zero with no-op patch' '
 	test_must_fail git apply --check input
 '
 
+test_expect_success '`apply --recount` allows no-op patch' '
+	echo 1 >1 &&
+	git apply --recount --check <<-\EOF
+	diff --get a/1 b/1
+	index 6696ea4..606eddd 100644
+	--- a/1
+	+++ b/1
+	@@ -1,1 +1,1 @@
+	 1
+	EOF
+'
+
 test_expect_success 'invalid combination: create and copy' '
 	test_must_fail git apply --check - <<-\EOF
 	diff --git a/1 b/2

gitgitgadget

Looks good to me.