From: Alan Mackenzie <acm@muc.de>
Date: Sat, 2 Mar 2019 18:23:34 +0000 (+0000)
Subject: Check by eassert that a bytepos argument isn't in the middle of a character
X-Git-Tag: emacs-27.0.90~3500
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=954c9c5bc344cdd6b201c2260b306ec0999aff24;p=emacs.git

Check by eassert that a bytepos argument isn't in the middle of a character

* src/marker.c (buf_bytepos_to_charpos): Add an eassert to check that the
parameter bytepos is at the beginning of a character or EOB.
---

diff --git a/src/marker.c b/src/marker.c
index b58051a8c2b..0b2e1bf5c6b 100644
--- a/src/marker.c
+++ b/src/marker.c
@@ -332,6 +332,10 @@ buf_bytepos_to_charpos (struct buffer *b, ptrdiff_t bytepos)
   if (best_above == best_above_byte)
     return bytepos;
 
+  /* Check bytepos is not in the middle of a character. */
+  eassert (bytepos >= BUF_Z_BYTE (b)
+           || CHAR_HEAD_P (BUF_FETCH_BYTE (b, bytepos)));
+
   best_below = BEG;
   best_below_byte = BEG_BYTE;