commit f6db314590fc96c0cdbf87367b47da8603e17ae9
from: Neels Hofmeyr <neels@hofmeyr.de>
date: Fri Oct 30 03:56:10 2020 UTC

fix result chunks: add minus above plus failed to shift "empty" positions

commit - c672cd5263e14c546a06d2b2132fd05bf20bbca0
commit + f6db314590fc96c0cdbf87367b47da8603e17ae9
blob - 3707ff39d6fbd6d28afc2a01bc56bd367ffec06c
blob + 69aea0a6aaf3ddfe78f7567e8a2405ae2d0c81e0
--- lib/diff_main.c
+++ lib/diff_main.c
@@ -220,6 +220,7 @@ diff_state_add_solved_chunk(struct diff_state *state,
 	struct diff_chunk *new_chunk;
 	enum diff_chunk_type last_t;
 	enum diff_chunk_type new_t;
+	struct diff_chunk *last;
 
 	/* Append to solved chunks; make sure that adjacent chunks of same type are combined, and that a minus chunk
 	 * never directly follows a plus chunk. */
@@ -277,10 +278,26 @@ diff_state_add_solved_chunk(struct diff_state *state,
 			if (!new_chunk)
 				return NULL;
 			*new_chunk = *chunk;
+
+			/* The new minus chunk indicates to which position on
+			 * the right it corresponds, even though it doesn't add
+			 * any lines on the right. By moving above a plus chunk,
+			 * that position on the right has shifted. */
+			last = &result->head[result->len - 1];
+			new_chunk->right_start = last->right_start;
 
 			debug("  - added minus-chunk follows plus-chunk,"
 			      " put before that plus-chunk\n");
 		}
+
+		/* That last_t == CHUNK_PLUS indicates to which position on the
+		 * left it corresponds, even though it doesn't add any lines on
+		 * the left. By inserting/extending the prev_last_t ==
+		 * CHUNK_MINUS, that position on the left has shifted. */
+		last = &result->head[result->len - 1];
+		last->left_start = new_chunk->left_start
+			+ new_chunk->left_count;
+
 	} else {
 		ARRAYLIST_ADD(new_chunk, *result);
 		if (!new_chunk)