Re: undo weirdness with insert-file-contents

[martin rudalics]

This is trickier than I thought.  The primary reason of the bug is that
record_insert combines two adjacent insertions thus messing up my
comparison after format decoding wrt the start of the inserted region.
Unless someone has a better idea, I'd handle this by inserting an undo
boundary for `insert-file-contents'.  The second problem is that
`insert-file-contents' does not consider an insertion a buffer change
when the buffer is empty.  This is obviously TRT in the file-visiting
case, but doesn't seem quite right in the non-visiting case.  Both
issues are involved in the buggy behaviors observed.  Please try another
time with the attached patch (I'm afraid it won't be the last).

*** fileio.c.~1.602.~   Thu Feb 14 20:41:44 2008
--- fileio.c    Fri Feb 29 23:30:18 2008
***************
*** 3730,3735 ****
--- 3730,3736 ----
    int read_quit = 0;
    Lisp_Object old_Vdeactivate_mark = Vdeactivate_mark;
    int we_locked_file = 0;
+   Lisp_Object original_undo_list = current_buffer->undo_list;
  
    if (current_buffer->base_buffer && ! NILP (visit))
      error ("Cannot do file visiting in an indirect buffer");
***************
*** 4589,4594 ****
--- 4590,4610 ----
        current_buffer->enable_multibyte_characters = Qnil;
      }
  
+   if (inserted > 0
+       && CONSP (current_buffer->undo_list)
+       && (! NILP (XCAR (current_buffer->undo_list))))
+     /* Insert an undo boundary unless there's one here. */
+     current_buffer->undo_list =
+       Fcons (Qnil, current_buffer->undo_list);
+   else if (inserted > 0
+          && (! EQ (original_undo_list, Qt))
+          && (NILP (visit)) && (NILP (replace)))
+     /* Assure that the first insertion is counted as a change. */
+     {
+       current_buffer->undo_list = Qnil;
+       record_first_change ();
+     }
+ 
    coding.dst_multibyte = ! NILP (current_buffer->enable_multibyte_characters);
    if (CODING_MAY_REQUIRE_DECODING (&coding)
        && (inserted > 0 || CODING_REQUIRE_FLUSHING (&coding)))