[PATCH 1/1] apply --recount: allow "no-op hunks"

[Johannes Schindelin via GitGitGadget]

From: Johannes Schindelin <johannes.schinde...@gmx.de>

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.

Signed-off-by: Johannes Schindelin <johannes.schinde...@gmx.de>
---
 apply.c                |  2 +-
 t/t4136-apply-check.sh | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/apply.c b/apply.c
index 073d5f0451..76955afb00 100644
--- a/apply.c
+++ b/apply.c
@@ -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;
diff --git a/t/t4136-apply-check.sh b/t/t4136-apply-check.sh
index 6d92872318..4c3f264a63 100755
--- a/t/t4136-apply-check.sh
+++ b/t/t4136-apply-check.sh
@@ -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
-- 
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