As pointed out in [1], when insert mode autocomplete is disabled,
<c-n> could be used to activate insert mode completions temporarily
[2]. This regressed in 6f7c5aed (Do not show custom completions when
autocomplete is off, 2022-01-03). Fix this by enabling completions
on <c-n>/<c-p>. This allows us to remove a special case for explicit
completers.
Alternative behavior (future?): make <c-n> toggle completion like
<c-o>. This can be done today, as suggested by Screwtape on IRC:
map global insert <c-n> %{<c-o><c-n><a-;>:toggle-ctrl-n<ret>}
define-command toggle-ctrl-n %{
hook global InsertCompletionShow .* %{ map window insert <c-n> <c-n> }
hook global InsertCompletionHide .* %{ unmap window insert <c-n> <c-n> }
}
[1] https://github.com/mawww/kakoune/pull/4493#issuecomment-1031189823
[2] <c-n> completion only lives for the lifetime of the completion
menu, whereas <c-o> lasts until you exit insert mode. This means
that autocompletion is much more convenient than <c-n> or <c-x>f,
because those require an explicit completion request for each
path component.
As reported in [1], completions provided by "set global completers
option=my_completion" activate insert mode autocompletion, even when
the autocomplete option does not have the insert mode flag.
This happens because InsertCompleter::on_option_changed() calls
InsertCompleter::setup_ifn(), which shows the completion pager.
Fix this by computing whether the completion pager is enabled;
otherwise we can return early from setup_ifn().
The completion pager is enabled if the autocompletion bit is set,
or if the user has requested explicit completion.
[1]: https://github.com/kak-lsp/kak-lsp/issues/585
