Perl_sv_pos_b2u now calls utf8_mg_len_cache_update for the string end offset.

Previously it would not take special action if the offset requested happened to
be the end of the string, meaning that the (fixed size) UTF-8 offset cache
would be used for a value which could (and should) be stored elsewhere.

1 files changed, 6 insertions, 2 deletions

diff --git a/sv.c b/sv.c
index ce16db6288..3a25abcf10 100644
--- a/sv.c
+++ b/sv.c
@@ -6676,8 +6676,12 @@ Perl_sv_pos_b2u(pTHX_ register SV *const sv, I32 *const offsetp)
     }
     *offsetp = len;
 
-    if (PL_utf8cache)
-	utf8_mg_pos_cache_update(sv, &mg, byte, len, blen);
+    if (PL_utf8cache) {
+	if (blen == byte)
+	    utf8_mg_len_cache_update(sv, &mg, len);
+	else
+	    utf8_mg_pos_cache_update(sv, &mg, byte, len, blen);
+    }
 }
 
 /*