(Finsert_file_contents): Give up match-end only if

coding requires conversion.  Adjust end of non-matching text area
to multibyte character boundary if enable_multibyte_character is non-nil.

1 files changed, 8 insertions, 1 deletions

diff --git a/src/fileio.c b/src/fileio.c
index 1526015921a..5d9352ed754 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -3291,7 +3291,8 @@ This does code conversion according to the value of\n\
                  we cannot use this method; giveup and try the other.  */
               if (same_at_end > same_at_start
                   && FETCH_BYTE (same_at_end - 1) >= 0200
-                  && ! NILP (current_buffer->enable_multibyte_characters))
+                  && ! NILP (current_buffer->enable_multibyte_characters)
+                  && CODING_REQUIRE_CONVERSION (&coding))
                 giveup_match_end = 1;
               break;
             }
@@ -3302,6 +3303,12 @@ This does code conversion according to the value of\n\
         {
           /* We win!  We can handle REPLACE the optimized way.  */
 
+          /* Extends the end of non-matching text area to multibyte
+             character boundary.  */
+          if (! NILP (current_buffer->enable_multibyte_characters))
+            while (same_at_end < ZV && ! CHAR_HEAD_P (POS_ADDR (same_at_end)))
+              same_at_end++;
+
           /* Don't try to reuse the same piece of text twice.  */
           overlap = same_at_start - BEGV - (same_at_end + st.st_size - ZV);
           if (overlap > 0)