setqflist called from autocmd does not change current qf list

[damage220]

• nvim --version: NVIM v0.4.3
• vim -u DEFAULTS (version: 8.1, patches 1-2268) behaves the same.
• Operating system/version: Arch Linux
• Terminal name/version: termite v15
• $TERM: xterm-termite

Steps to reproduce using nvim -u NONE

nvim -u NONE your-project
mistype something to populate qf list
:autocmd QuickFixCmdPost make call setqflist([], "a", {"nr": 2, "items": []})
:make
:cwindow
:chistory

Actual behaviour

After qf list is populated, the autocmd above creates another qf list at index 2. The initial qf list is still selected:

> error list 1 of 2; 13 errors    :make
  error list 2 of 2; 0 errors     :setqflist()

Expected behaviour

After qf list is populated, the autocmd above should create another qf list at index 2 and set it as the selected. Like when I call setqflist manually after :make.

  error list 1 of 2; 13 errors    :make
> error list 2 of 2; 0 errors     :setqflist()

[justinmk]

vim -u DEFAULTS (version: 8.1, patches 1-2268) behaves the same.

@chrisbra @yegappan is this expected behavior?

[damage220]

I am not sure whether this is intentional or not, but I think the behavior should be consistent both for autocmd and mapping/calling manually, unless the opposite is specified in the help. Also, here is the output of the following autocmd in vim 8.1:

autocmd QuickFixCmdPost make chist | call setqflist([], " ") | chist

> error list 1 of 1; 13 errors    :make
[setqflist call]
  error list 1 of 2; 13 errors    :make
> error list 2 of 2; 0 errors     :setqflist()

And when I type :chist again, it is already:

> error list 1 of 2; 13 errors    :make`
  error list 2 of 2; 0 errors     :setqflist()

No mention about restrictions on setqflist() (like sandbox or textlock) in the help page (did I miss something?). Again, it works if I just type :call setqflist([], " ") or call it from mapping. By the way, setloclist() is also affected.

These caused UB in my plugin.

" create copy of the initial qf list to be able to restore it in the future
" produces list #2
call setqflist(getqflist(), " ")

" filter current list and apply it
" because vim set #2 as current list, "r" flag make vim to redraw qf window
call setqflist(filtered_items, "r")

When autocmd handler has finished, vim restore current qf list to #1 and completely breaks qf window. qf window contains items from list #2, but commands like :cnext operate on list #1. QuickFixLine syntax group is broken, too.