E420 when hi Normal has ctermbg=None

[pansz]

When Normal highlight has ctermbg=None, this means a transparent term background, i.e. the same color as the background of Term Client Program, if the term client supports a picture as background, then the background will be the picture. This technique was widely used when we need a background picture for term client.

Vim will issue E420 when ctermfg=bg, if ctermbg=None

The following line:

sil! exe 'hi CtrlPLinePre '.( has("gui_running") ? 'gui' : 'cterm' ).'fg=bg'

should not be used since ctermfg=bg may fail.

Well, I don't know why ctermfg=bg is used, do you want to Hide the foreground? Will this work?

hi link CtrlPLinePre Ignore

[pansz]

I had tried to use

hi link CtrlPLinePre Ignore

And it seems to work great.

[kien]

I already made some changes that should (unintentionally) fix this, I think. Let me know if this doesn't return either -1 or an empty string:

:echo synIDattr(synIDtrans(hlID('Normal')), 'bg')

[pansz]

This returns -1 for me.

So, hi link CtrlPLinePre Ignore isn't a better approach? (I think all colors should be defined by color scheme and plugins should only use hi link)

[kien]

Because not every colorscheme uses guifg=bg or ctermfg=bg for Ignore (molokai for example, uses a visible color for this group's foreground). So it's better using the Normal's bg directly.

[pansz]

Well, it is all about choice. If a colorscheme choose to use a visible color for Ignore, then it does meant to let user see what is intend to be hidden. And if a user choose to use such a colorscheme without any modification, this means he/she choose to see the hidden text (with a dim color, of course).

When a colorscheme set ctermbg=None and use a background picture, it is impossible to hide the text completely, but the colorscheme may choose a foreground color very close to the background picture in order to make the text almost invisible, and define that group to be "Ignore".

[kien]

This should be fixed in 75e31e9.

It's also now possible to change the default highlighting for every part of the prompt.