[PATCH] diff: fix --color-moved-ws=allow-indentation-change

From: Phillip Wood <phillip.wood@talktalk.net>
Date: Sep 4, 2018, 13:52 UTC
Message-ID: <20180904135258.31300-1-phillip.wood@talktalk.net>

From: Phillip Wood <phillip.wood@dunelm.org.uk>

If there is more than one potential moved block and the longest block is not the first element of the array of potential blocks then the block is cut short. With --color-moved=blocks this can leave moved lines unpainted if the shortened block does not meet the block length requirement. With --color-moved=zebra then in addition to the unpainted lines the moved color can change in the middle of a single block.

Fix this by freeing the whitespace delta of the match we're discarding rather than the one we're keeping.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
---

While I was working on this I spotted a couple of other issues I don't have time to fix myself at the moment, so I thought I mention them in case someone else wants to pick them up

1) I think there is a potential memory leak at the end of
   mark_color_as_moved(). If pmb_nr > 0 then the whitespace deltas
   need freeing before freeing pmb itself.

2) The documentation could be improved to explain that
   allow-indentation-change does not work with indentation that
   contains a mix of tabs and spaces and the motivation for that
   (python?) [I've got some code to add an option that supports that
   which I'll post when I've written some tests after 2.19 is
   released]

 diff.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/diff.c b/diff.c
index 145cfbae5..4e8f725bb 100644
--- a/diff.c
+++ b/diff.c
@@ -968,8 +968,13 @@ static void pmb_advance_or_null_multi_match(struct diff_options *o,
 			/* Carry the white space delta forward */
 			pmb[i]->next_line->wsd = pmb[i]->wsd;
 			pmb[i] = pmb[i]->next_line;
-		} else
+		} else {
+			if (pmb[i]->wsd) {
+				free(pmb[i]->wsd->string);
+				FREE_AND_NULL(pmb[i]->wsd);
+			}
 			pmb[i] = NULL;
+		}
 	}
 }
 
@@ -990,10 +995,6 @@ static int shrink_potential_moved_blocks(struct moved_entry **pmb,
 
 		if (lp < pmb_nr && rp > -1 && lp < rp) {
 			pmb[lp] = pmb[rp];
-			if (pmb[rp]->wsd) {
-				free(pmb[rp]->wsd->string);
-				FREE_AND_NULL(pmb[rp]->wsd);
-			}
 			pmb[rp] = NULL;
 			rp--;
 			lp++;

-- 
2.18.0