Test explicitness of as_const_view's functions

Author: frederick-vs-ja

libcxx/test/std/ranges/range.adaptors/range.as.const/ctor.pass.cpp

@@ -37,11 +37,14 @@ static_assert(std::is_constructible_v<std::ranges::as_const_view<NonDefaultConst
 static_assert(std::is_nothrow_constructible_v<std::ranges::as_const_view<DefaultConstructibleView>>);
 
 template <class T, class... Args>
-concept IsImplicitlyConstructible = requires(T val, Args... args) { val = {std::forward<Args>(args)...}; };
+concept IsImplicitlyConstructible = requires(void (&fun)(T), Args&&... args) { fun({std::forward<Args>(args)...}); };
 
 static_assert(IsImplicitlyConstructible<std::ranges::as_const_view<DefaultConstructibleView>>);
 static_assert(!IsImplicitlyConstructible<std::ranges::as_const_view<NonDefaultConstructibleView>, int>);
 
+static_assert(std::is_constructible_v<std::ranges::as_const_view<DefaultConstructibleView>>, DefaultConstructibleView);
+static_assert(!std::is_convertible_v<DefaultConstructibleView, std::ranges::as_const_view<DefaultConstructibleView>>);
+
 constexpr bool test() {
   std::ranges::as_const_view<DefaultConstructibleView> view = {};
   assert(view.base().i_ == 23);