How to use tmap with <Plug>?

Question

I am wondering how shall I use tmap along with <Plug>.

Here is a snippet of the context where I am using it:

vim9script 

import autoload "../lib/foo.vim"

noremap <unique> <script> <Plug>DoSomething :call <SID>foo.DoSomething()

if !hasmapto('<Plug>DoSomething') || empty(mapcheck("<F2>", "t"))
    tmap <silent> <F2> <c-w><Plug>DoSomething<cr>
endif

When I use hit <F2>, nothing happens but a sound is emitted.

Answer 1

So, there are a few issues with your example:

• the two first lines are irrelevant if you don't also include the content of the imported script, because a) we have no idea what DoSomething() does and b) the rest doesn't use the vim9script syntax anyway,
• the use of <unique> makes it impossible to iterate while testing,
• the conditional check is also irrelevant.

Here is an actual minimal reproducible example:

noremap <script> <Plug>DoSomething :echo 'Do something.'
tmap <silent> <F2> <c-w><Plug>DoSomething<cr>

The problem is that your <Plug> mapping is defined for normal mode, visual mode, and operator-pending mode (:help :map) while you are trying to consume it in a terminal mode mapping. Changing it to a terminal mode mapping is an easy fix:

tnoremap <script> <Plug>DoSomething :echo 'Do something.'