Allow command modifiers for on-demand-loading commands

[subnut]

Before this commit, commands like this -

:tab Git diff HEAD^ HEAD

were interpreted like this -

:Git diff HEAD^ HEAD

This commit fixes that issue.

[tomtomjhj]

I think this needs a version guard because <mods> is a relatively new feature (v7.4.1898)

[subnut]

@tomtomjhj 2016 is relatively new? For whom?
I'm not trying to be sarcastic... I am genuinely interested in knowing use-cases where people need to use vim versions as old as 2016.

---

TBH, I'd completely forgotten about this PR 😅

[tomtomjhj]

Of course, I believe 2016 feature is old enough to use without version check in 2021.
The only reason I think 2016 feature is relatively new is that vim-plug has checks for even older stuff, e.g.

• vim 7.3.442, 2012

  vim-plug/plug.vim

  Line 589 in c997134

  execute 'doautocmd' ((v:version > 703 || has('patch442')) ? '<nomodeline>' : '') join(a:000)

• git 2.0 2014 2f4e281

[janlazo]

I'm one of those people with old Vim versions so add a version,feature checks until @junegunn changes his mind on the minimum Vim/Neovim versions.

[subnut]

@janlazo Will do (please wait a few days, I am currently AFK).

I am curious about why you are still using such an old version of vim.
Can you please explain? 😅

[junegunn]

One of the strong selling points of vim-plug is its excellent backward compatibility. Most of its features work as expected even with Vim 7.0 which means that it works virtually everywhere. There can be various reasons you can't or won't use the latest versions of Vim (company guidelines, security requirements, systems with tiny resources, etc.), and still, you don't have to worry about vim-plug not working. That's a great thing and we're not going to lose that.

[janlazo]

@subnut Old company servers. Difficult to install or upgrade dev packages, even if it's just a newer version of Vim. Some of my colleagues don't know or care that vi,vim,$EDITOR is any version of vim. I doubt anybody there is aware of :terminal command. Some OS packages of vim disable some features are missing a few patches that I need to reliably use the new features (ie. :packadd).

[subnut]

Tried implementing the version guard in 82ffd4f
Please check if the implementation is correct

[subnut]

@janlazo @junegunn What is blocking this PR from being merged?