Make <c-n> show completion menu again when autocomplete is off

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.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/insert_completer.cc b/src/insert_completer.cc
index f32b35ca..8f67f155 100644
--- a/src/insert_completer.cc
+++ b/src/insert_completer.cc
@@ -414,6 +414,7 @@ InsertCompleter::~InsertCompleter()
 
 void InsertCompleter::select(int index, bool relative, Vector<Key>& keystrokes)
 {
+    m_enabled = true;
     if (not setup_ifn())
         return;
 
@@ -461,7 +462,7 @@ void InsertCompleter::select(int index, bool relative, Vector<Key>& keystrokes)
 
 void InsertCompleter::update(bool allow_implicit)
 {
-    m_enabled = allow_implicit or m_explicit_completer;
+    m_enabled = allow_implicit;
     if (m_explicit_completer and try_complete(m_explicit_completer))
         return;