How to bind Ctrl-Enter in fish?

In order to configure a user binding (version 2.2.0), it must be in the fish_user_key_bindings function:

function fish_user_key_bindings    bind \n 'commandline -f accept-autosuggestion execute'end

This works fine.

I wanted to expand this binding to Ctrl+Enter, by using the appropriate modifier:

function fish_user_key_bindings    bind \c\n 'commandline -f accept-autosuggestion execute'end

This does not work: Enter uses the current (up to the cursor) suggestion (which is the default) but Ctrl+Enter as well (as if the action with the modifier was not taken into account)