* src/marker.c (buf_bytepos_to_charpos): Re-add the CHAR_HEAD_P assertion

This assertion was removed in 1c349c62305d432abf0fa2b6e3f5d754fe4cab79
because the assumption was invalid during set_intervals_multibyte_1.
So we change set_intervals_multibyte_1 to solve the problem in the same
way as in the rest of Fset_buffer_multibyte, which actually simplifies
the code.

* src/buffer.c (advance_to_char_boundary): Not static any more.
* src/buffer.h (advance_to_char_boundary): Add prototype.
* src/intervals.c (set_intervals_multibyte_1): Use it.

1 files changed, 6 insertions, 30 deletions

diff --git a/src/intervals.c b/src/intervals.c
index 8f39c45762f..34829ab050d 100644
--- a/src/intervals.c
+++ b/src/intervals.c
@@ -2335,22 +2335,10 @@ set_intervals_multibyte_1 (INTERVAL i, bool multi_flag,
       if (multi_flag)
         {
           ptrdiff_t temp;
-          left_end_byte = start_byte + LEFT_TOTAL_LENGTH (i);
+          left_end_byte
+            = advance_to_char_boundary (start_byte + LEFT_TOTAL_LENGTH (i));
           left_end = BYTE_TO_CHAR (left_end_byte);
-
-          temp = CHAR_TO_BYTE (left_end);
-
-          /* If LEFT_END_BYTE is in the middle of a character,
-             adjust it and LEFT_END to a char boundary.  */
-          if (left_end_byte > temp)
-            {
-              left_end_byte = temp;
-            }
-          if (left_end_byte < temp)
-            {
-              left_end--;
-              left_end_byte = CHAR_TO_BYTE (left_end);
-            }
+          eassert (CHAR_TO_BYTE (left_end) == left_end_byte);
         }
       else
         {
@@ -2369,22 +2357,10 @@ set_intervals_multibyte_1 (INTERVAL i, bool multi_flag,
         {
           ptrdiff_t temp;
 
-          right_start_byte = end_byte - RIGHT_TOTAL_LENGTH (i);
+          right_start_byte
+            = advance_to_char_boundary (end_byte - RIGHT_TOTAL_LENGTH (i));
           right_start = BYTE_TO_CHAR (right_start_byte);
-
-          /* If RIGHT_START_BYTE is in the middle of a character,
-             adjust it and RIGHT_START to a char boundary.  */
-          temp = CHAR_TO_BYTE (right_start);
-
-          if (right_start_byte < temp)
-            {
-              right_start_byte = temp;
-            }
-          if (right_start_byte > temp)
-            {
-              right_start++;
-              right_start_byte = CHAR_TO_BYTE (right_start);
-            }
+          eassert (CHAR_TO_BYTE (right_start) == right_start_byte);
         }
       else
         {