Make the patch -x option (only enabled with CONFIG_DEBUG) provide more information about why a patch didn't apply. (Offset of first nonmatching character at each line during seek phase.)

1 files changed, 7 insertions, 1 deletions

diff --git a/toys/posix/patch.c b/toys/posix/patch.c
index 7fb6add3..ae24ff94 100644
--- a/toys/posix/patch.c
+++ b/toys/posix/patch.c
@@ -201,7 +201,13 @@ static int apply_one_hunk(void)
         // Match failed.  Write out first line of buffered data and
         // recheck remaining buffered data for a new match.
 
-        if (PATCH_DEBUG) fprintf(stderr, "NOT: %s\n", plist->data);
+        if (PATCH_DEBUG) {
+          int bug = 0;
+
+          while (plist->data[bug] == check->data[bug]) bug++;
+          fprintf(stderr, "NOT(%d:%d!=%d): %s\n", bug, plist->data[bug],
+            check->data[bug], plist->data);
+        }
 
         TT.state = 3;
         do_line(check = dlist_pop(&buf));