Prompt redraw bugs out when editing with a multiline prompt with fzf

[nhooyr]

fish, version 3.0.2

Darwin ien.local 18.6.0 Darwin Kernel Version 18.6.0: Thu Apr 25 23:16:27 PDT 2019; root:xnu-4903.261.4~2/RELEASE_X86_64 x86_64

xterm-256color

Minimal config.fish:

function fish_prompt
    echo FIRST
    echo -n 'SECOND$ '
end

function fzf-bind-1
    fzf --height 40%
    commandline -t 1
    commandline -f repaint
end
bind \ea fzf-bind-1

function fzf-bind-2
    fzf --height 40%
    commandline -f repaint
end
bind \es fzf-bind-2

function fzf-bind-3
    commandline -t 1
    commandline -f repaint
end
bind \ed fzf-bind-3

function fzf-bind-4
    fzf --height 40%
end
bind \ef fzf-bind-4

1. Move minimal config.fish into /tmp/home/.config/fish/config.fish

sh -c 'env HOME=/tmp/home fish'

3. Press alt+a to run fzf-bind-1. Exit fzf by pressing esc, you'll see the FIRST line of the prompt twice.

4. The second bind will show what happens when nothing is inserted, no additional FIRST line appears. The prompt looks normal.

5. The third bind shows what happens when fzf isn't ran but 1 is inserted, no additional FIRST line appears.

6. The fourth bind shows what happens right after fzf runs. The SECOND line of the prompt is missing.

Related: junegunn/fzf#1607

I believe its a fish bug and not an fzf bug due to other similar open issues like #5860 and that it only happens if you insert something into the commandline, repaint works normally without insertion.

[nhooyr]

Fifth binding:

function fzf-bind-5
    fzf --height 40%
    commandline -t 1
end
bind \eg fzf-bind-5

Shows what happens without commandline -f repaint.

So the issue is reproducible by running just fzf followed by an commandline insertion.

[rouge8]

#5860 might be the cause of this. Adding printf '\033[J' to the start of my fish_prompt, as suggested in #5860 (comment), fixes the issue.

[zanchey]

#5860 fixes the first issue, but not the fourth or fifth.

[mk12]

It's still broken for me on fish 3.3.1. Every step (a to g) reproduces exactly as described by @nhooyr. Adding printf '\033[J' to the start of fish_prompt makes no difference for me. In that comment they say fish is drawing the prompt in the right place, but neglecting to clear the screen below. For me, it seems more that fish is just drawing the prompt in the wrong place, one line lower than it should.

I've found a different workaround, though. I just move the cursor up after invoking fzf:

function fzf-bind-1
    set result (fzf --height 40%)
    printf "\033[A"
    commandline -t 1
    commandline -f repaint
end
bind \ea fzf-bind-1

I'm also capturing the output of fzf to avoid printing it to the screen, allowing me to test that this works properly when you make a selection (i.e. press Enter instead of Escape).