startpos = marker_position (w->start);
startpos_byte = marker_byte_position (w->start);
height = WINDOW_TOTAL_LINES (w);
+ /* We cannot cope with w->start being outside of the
+ accessible portion of the buffer; in particular,
+ display_count_lines call below will infloop if called with
+ startpos_byte outside of the [BEGV_BYTE..ZV_BYTE] region.
+ Such w->start means we were called in some "creative" way
+ when the buffer's restriction was changed, but the window
+ wasn't yet redisplayed after that. If that happens, we
+ need to determine a new base line. */
+ if (!(BUF_BEGV_BYTE (b) <= startpos_byte
+ && startpos_byte <= BUF_ZV_BYTE (b)))
+ {
+ startpos = BUF_BEGV (b);
+ startpos_byte = BUF_BEGV_BYTE (b);
+ w->base_line_pos = 0;
+ w->base_line_number = 0;
+ }
/* If we decided that this buffer isn't suitable for line numbers,
don't forget that too fast. */