Add as(strict) casts

Author: filipsajdak

include/cpp2util.h

@@ -683,6 +683,19 @@ auto as(T&& t) -> auto
     return cpp2::optional_as<C>(std::forward<T>(t));
 }
 
+template< typename T >
+struct strict {
+    using type = T;
+};
+
+template< typename S, typename T >
+auto as(T&& t) -> auto
+    requires (is<cpp2::strict>(S{}))
+{
+    using C = typename S::type;
+    return cpp2::strict_as<C>(std::forward<T>(t));
+}
+
 //-------------------------------------------------------------------------------------------------------------
 //  std::variant is and as
 //