Whitespace Issues with prompt, on VSCode's integrated terminal

[pradyunsg]

Issue Type: Bug
Component: Integrated Terminal

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A picture's worth a 1000 words, so here are 2 pictures. :)

VS Code Integrated Terminal:

MacOS's Terminal:

The main difference is when there's an RPROMPT, VS Code's Integrated Terminal does not seem to properly render/add the space that's at the end of the PS1. Both are using the same zsh executable, with the same "Iosevka Nerd Font".

Copy Pasted Text, from these sessions

VS Code:

     echo "this is good" && show
this is good
PS1 = b'%{\x1b[35;1H%}%{\x1b[38;5;255m%}%{\x1b[48;5;26m%}%{\x1b[38;5;255m%}  \xef\x80\x95  %{\x1b[38;5;26m%}%{\x1b[48;5;76m%}\xee\x82\xb0%{\x1b[38;5;228m%}%{\x1b[48;5;76m%}%{\x1b[39;49m%}%{\x1b[38;5;76m%}\xee\x82\xb0%{\x1b[39;49m%} '
RPROMPT = b''
     sleep 1                    
    echo "this is bad" && show                                                                                                                                                         1.018 
this is bad
PS1 = b'%{\x1b[35;1H%}%{\x1b[38;5;255m%}%{\x1b[48;5;26m%}%{\x1b[38;5;255m%}  \xef\x80\x95  %{\x1b[38;5;26m%}%{\x1b[48;5;76m%}\xee\x82\xb0%{\x1b[38;5;228m%}%{\x1b[48;5;76m%}%{\x1b[39;49m%}%{\x1b[38;5;76m%}\xee\x82\xb0%{\x1b[39;49m%} '
RPROMPT = b'%{\x1b[38;5;167m%}\xee\x82\xb2%{\x1b[38;5;255m%}%{\x1b[48;5;167m%} 1.018 %{\x1b[39;49m%}'
     which show                 
show: aliased to python3 -c "print('PS1 =', '${PS1}'.encode('utf-8')); print('RPROMPT =', '${RPROMPT}'.encode('utf-8'))"

MacOS Terminal:

     echo "this is good" && show
this is good
PS1 = b'%{\x1b[25;1H%}%{\x1b[38;5;255m%}%{\x1b[48;5;26m%}%{\x1b[38;5;255m%}  \xef\x80\x95  %{\x1b[38;5;26m%}%{\x1b[48;5;76m%}\xee\x82\xb0%{\x1b[38;5;228m%}%{\x1b[48;5;76m%}%{\x1b[39;49m%}%{\x1b[38;5;76m%}\xee\x82\xb0%{\x1b[39;49m%} '
RPROMPT = b''
     sleep 1                    
     echo "this is good" && show                                                                                                                                 1.015 
this is good
PS1 = b'%{\x1b[25;1H%}%{\x1b[38;5;255m%}%{\x1b[48;5;26m%}%{\x1b[38;5;255m%}  \xef\x80\x95  %{\x1b[38;5;26m%}%{\x1b[48;5;76m%}\xee\x82\xb0%{\x1b[38;5;228m%}%{\x1b[48;5;76m%}%{\x1b[39;49m%}%{\x1b[38;5;76m%}\xee\x82\xb0%{\x1b[39;49m%} '
RPROMPT = b'%{\x1b[38;5;167m%}\xee\x82\xb2%{\x1b[38;5;255m%}%{\x1b[48;5;167m%} 1.015 %{\x1b[39;49m%}'
     which show                 
show: aliased to python3 -c "print('PS1 =', '${PS1}'.encode('utf-8')); print('RPROMPT =', '${RPROMPT}'.encode('utf-8'))"

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VS Code version: Code 1.37.0 (036a6b1, 2019-08-08T01:22:37.660Z)
OS version: Darwin x64 18.6.0
Extensions: none

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz (8 x 2500)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on native_gpu_memory_buffers: enabled oop_rasterization: disabled_off protected_video_decode: unavailable_off rasterization: enabled skia_deferred_display_list: disabled_off skia_renderer: disabled_off surface_synchronization: enabled_on video_decode: enabled viz_display_compositor: disabled_off webgl: enabled webgl2: enabled
Load (avg)	2, 2, 2
Memory (System)	16.00GB (0.55GB free)
Process Argv	-psn_0_602259
Screen Reader	no
VM	0%

[Tyriar]

The issue is the emoji, tracked in xtermjs/xterm.js#1709

[pradyunsg]

That character is not an emoji. It's nf-fa-home from NerdFonts.

Removing it from the prompt, the issue still occurs:

This prompt has been working for me, since before the July update and that issue is a lot older than that.

[pradyunsg]

(for folks following via email, I added more information to the comment above)

[Tyriar]

@pradyunsg the problem isn't restricted to just emoji but other ambiguous width unicode characters as well.

[pradyunsg]

nods That makes sense.

Would it be possible for you to look into/provide pointers to what change might have affected this, between the June and July releases? I am more than willing to volunteer my time to help resolve this issue.

I can confirm that June release works well for me -- I've downgraded for now.

[Tyriar]

It's a pretty involved issue that will probably eventually be tackled by @jerch, lots of history you can read on xtermjs/xterm.js#1709 and linked issues/prs.