wrong change.lnum for listener_add callback #9768

Steps to reproduce

$ cat <<"EOF" > listener-bug-report-minimal.vim
call setbufline(1, 1, ['pre ( part of line',
            \ 'whole line',
            \ 'part of line ) post'])

let g:lst = []
function EchoChanges(bufnr, start, end, added, changes)
  for l:change in a:changes
    let l:change.lines = getbufline(a:bufnr, l:change.lnum, l:change.end-1+l:change.added)
  endfor
  call add(g:lst, a:changes)
  call writefile([string(a:changes)], '/tmp/listener.log', 'a')
endfunction
call listener_add("EchoChanges")

let @a=[
 \ 'Cb_mirror',
 \ 'line    2:',
 \ 'E578: Not allowed to change text here'
 \ ]->join("\n")
EOF

then open vim by

$ vim --clean -c "so listener-bug-report-minimal.vim"

inside vim, initiate 2 changes by run two command manually (or typing without call feedkyes)

    call feedkeys('7|viw"ap')
    call feedkeys('u')

Expected behaviour

The last change is incorrect. after call feedkeys('u'), a changes list with two change item being reported, i.e.,

[{'lnum': 1, 'col': 1, 'added': -2, 'end': 4, 'lines': ['pre ( part of line']}, 
 {'lnum': 2, 'col': 1, 'added': 0, 'end': 2, 'lines': []}]

the second change.lnum is wrong, which should be 1.
I'm not sure the first change is right or not, since the meaning of lnum and end is not precisely defined, with regard to write a 100-percent reliable buffer mirror tool.

My thought on changes call feedkeys('u') should report:

case 1 un-merged

• two change being reported
• first change, two lines deleted, line 2 and 3
• second change, one line being changed, line 1 from pre ( Cb_mirror to pre ( part of line
• in this specific scenario the order is unimportant and can be swapped

case 2 merged

• only 1 change being reported
• line 1 changed, line 2 and 3 deleted

Version of Vim

VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Oct 01 2021 01:51:08) Included patches: 1-2434 Extra patches: 8.2.3402, 8.2.3403, 8.2.3409, 8.2.3428 Modified by team+vim@tracker.debian.org Compiled by team+vim@tracker.debian.org Huge version without GUI. Features included (+) or not (-): +acl +ipv6 +ruby +arabic +job +scrollbind +autocmd +jumplist +signs +autochdir +keymap +smartindent -autoservername +lambda -sound -balloon_eval +langmap +spell +balloon_eval_term +libcall +startuptime -browse +linebreak +statusline ++builtin_terms +lispindent -sun_workshop +byte_offset +listcmds +syntax +channel +localmap +tag_binary +cindent +lua -tag_old_static -clientserver +menu -tag_any_white -clipboard +mksession +tcl +cmdline_compl +modify_fname +termguicolors +cmdline_hist +mouse +terminal +cmdline_info -mouseshape +terminfo +comments +mouse_dec +termresponse +conceal +mouse_gpm +textobjects +cryptv -mouse_jsbterm +textprop +cscope +mouse_netterm +timers +cursorbind +mouse_sgr +title +cursorshape -mouse_sysmouse -toolbar +dialog_con +mouse_urxvt +user_commands +diff +mouse_xterm +vartabs +digraphs +multi_byte +vertsplit -dnd +multi_lang +virtualedit -ebcdic -mzscheme +visual +emacs_tags +netbeans_intg +visualextra +eval +num64 +viminfo +ex_extra +packages +vreplace +extra_search +path_extra +wildignore -farsi +perl +wildmenu +file_in_path +persistent_undo +windows +find_in_path +popupwin +writebackup +float +postscript -X11 +folding +printer -xfontset -footer +profile -xim +fork() -python -xpm +gettext +python3 -xsmp -hangul_input +quickfix -xterm_clipboard +iconv +reltime -xterm_save +insert_expand +rightleft system vimrc file: "$VIM/vimrc" user vimrc file: "$HOME/.vimrc" 2nd user vimrc file: "~/.vim/vimrc" user exrc file: "$HOME/.exrc" defaults file: "$VIMRUNTIME/defaults.vim" fall-back for $VIM: "/usr/share/vim" Compilation: gcc -c -I. -Iproto -DHAVE_CONFIG_H -Wdate-time -g -O2 -ffile-prefix-map=/build/vim-DtwDbo/vim-8.2.2434=. -fstack-protector-strong -Wformat -Werror=format-security -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1 Linking: gcc -L. -Wl,-z,relro -Wl,-z,now -fstack-protector-strong -rdynamic -Wl,-export-dynamic -Wl,-E -Wl,-z,relro -Wl,-z,now -Wl,--as-needed -o vim -lm -ltinfo -lselinux -lacl -lattr -lgpm -ldl -L/usr/lib -llua5.2 -Wl,-E -fstack-protector-strong -L/usr/local/lib -L/usr/lib/x86_64-linux-gnu/perl/5.32/CORE -lperl -ldl -lm -lpthread -lcrypt -L/usr/lib/python3.9/config-3.9-x86_64-linux-gnu -lpython3.9 -lcrypt -lpthread -ldl -lutil -lm -lm -L/usr/lib/x86_64-linux-gnu -ltcl8.6 -ldl -lz -lpthread -lm -lruby-2.7 -lm -L/usr/lib

Environment

OS: Debian 11.1 without X11

$ cat /etc/debian_version
11.1

Logs and stack traces

No response