Is <c-g><c-g> equivalent to <nop> in insert mode?

Question

I've tried :help i_CTRL-G_CTRL-G and :helpgrep CTRL-G more generally and can't figure out why <c-g><c-g> is equivalent to a <nop> in insert mode.

For some context, I was having problems with the mapping:

nnoremap ` <nop>

And it was suggested in a comment here: Using a no-op key in insert mode, can't use key after using no-op mapping That I should use

nnoremap ` <c-g><c-g>

instead.

Using this workaround the problem is avoided, but I can't figure out why it works. In particular, I'm trying to understand how <c-g><c-g> duplicates some or perhaps all of the observable behavior of <nop> ... while simultaneously hitting a different enough codepath to avoid triggering the bug.

Answer 1

As you saw in your search :help i_CTRL-G_CTRL-G doesn't exist. It simply means that by default it is mapped to nothing thus pressing CTRL-GCTRL-G will do nothing which is equivalent to <nop>.

In their comment @Mass said it is a workaround: you are abusing the fact that CTRL-GCTRL-G does nothing to replicate the behavior of <nop> without sending the <nop> keycode. You could get the equivalent with basically any nonexisting mapping like <c-g><c-a>, <c-g><c-b>, etc