options/value: add `QObject::connect` wrapper

This is useful not just to save on complexity in call sites, but also
because I plan on using the Verdigris library to remove needless
`valueChanged()` and `setValue()` overloads from each `value<t>`
instance.

Also fix a bug in `options/tie.hpp` where `QComboBox::setCurrentIndex`
was erroneously called as `Qt::DirectConnection`.

1 files changed, 11 insertions, 0 deletions

diff --git a/options/value-traits.hpp b/options/value-traits.hpp
index 145cd924..e676f942 100644
--- a/options/value-traits.hpp
+++ b/options/value-traits.hpp
@@ -15,6 +15,17 @@ using cv_qualified =
                        std::remove_cvref_t<t>,
                        std::add_lvalue_reference_t<std::add_const_t<std::remove_cvref_t<t>>>>;
 
+template<typename t, typename = void>
+struct maybe_enum_type {
+    using type = t;
+};
+template<typename t>
+struct maybe_enum_type<t, std::enable_if_t<std::is_enum_v<t>>> {
+    using type = int;
+};
+
+template<typename t> using maybe_enum_type_t = typename maybe_enum_type<t>::type;
+
 template<typename t, typename u = t, typename Enable = void>
 struct default_value_traits
 {