Restoring a User{N} highlight inside an item group causes the whole item group to disappear

[antoineco]

Problem

Given:

• a Lua function that returns a string which can be expanded inside statusline (e.g. return '%1*hello%*')
• a statusline item group that expands the value returned by this function (e.g. %([%{%v:lua.myfunc()%}]%))

The entire item group disappears if the expansion contains a highlight restore item: either %* or %0*.

It does get rendered if a %N* item is positioned before the item group.

Steps to reproduce

nvim --clean

:hi User1 guifg=Red

:hi User2 guifg=Blue

:lua MyFunc = function() return "%1*MyFunc%*" end

1. Simple expansion, no other user highlight in the statusline:

   :set statusline=--%(x%{%v:lua.MyFunc()%}x%)--

   statusline is rendered without the item group, neither the colored text nor the inner 'x's are printed:
   

2. Item group prefixed with another user highlight (it doesn't matter which one):

   :set statusline=--%2*%(x%{%v:lua.MyFunc()%}x%)--

   statusline is rendered with the item group, but not with the desired appearance due to workarounds:
   

   Here the item group no longer disappears, but having to prefix it with a User{N} highlight is a hack that results in visual glitches, and possibly other side effects.

Expected behavior

In the first case above, the statusline should have been rendered with the text "MyFunc" highlighted in red, with all surrounding characters highlighted according to the built-in StatusLine highlight group:

Neovim version (nvim -v)

v0.11.0-dev-219+gc37695a5d

Vim (not Nvim) behaves the same?

N/A (no Lua)

Operating system/version

Debian 12

Terminal name/version

WezTerm

$TERM environment variable

wezterm

Installation

Build from repo

[antoineco]

Interestingly, it works as expected if the Lua function returns any expandable item between %1* and %*, as opposed to just the "MyFunc" text.

:lua MyFunc = function() return "%1*MyFunc%t%*" end

:set statusline=--%(x%{%v:lua.MyFunc()%}x%)--

[zeertzjq]

You don't need a Lua function to reproduce this. It also happens when putting it inside a string literal:

:set statusline=--%(x%{%'%1*MyFunc%*'%}x%)--

[zeertzjq]

Actually you don't need a expression either:

:set statusline=--%(x%1*MyFunc%*x%)--

[antoineco]

Thanks for pointing this out, I didn't even consider putting a string literal inside a %{% item.

I should report this in vim/vim. I'm closing this issue for now.

[antoineco]

This is indeed an upstream bug.
It was decided upstream that the bug wouldn't be fixed to avoid breaking people who rely on the behavior (see reference above.)