clarify assert information and correct the test

Author: Yuzhiy05

libcxx/include/__ranges/to.h

@@ -83,7 +83,7 @@ template <class _Container, input_range _Range, class... _Args>
   static_assert(!is_const_v<_Container>, "The target container cannot be const-qualified, please remove the const");
   static_assert(
       !is_volatile_v<_Container>, "The target container cannot be volatile-qualified, please remove the volatile");
-  static_assert(is_class_v<_Container> || is_union_v<_Container>, "The target must be a class type");
+  static_assert(is_class_v<_Container> || is_union_v<_Container>, "The target must be a class type or union type");
   // First see if the non-recursive case applies -- the conversion target is either:
   // - a range with a convertible value type;
   // - a non-range type which might support being created from the input argument(s) (e.g. an `optional`).
@@ -210,7 +210,7 @@ template <class _Container, class... _Args>
   static_assert(!is_const_v<_Container>, "The target container cannot be const-qualified, please remove the const");
   static_assert(
       !is_volatile_v<_Container>, "The target container cannot be volatile-qualified, please remove the volatile");
-  static_assert(is_class_v<_Container> || is_union_v<_Container>, "The target must be a class type");
+  static_assert(is_class_v<_Container> || is_union_v<_Container>, "The target must be a class type or union type");
   auto __to_func = []<input_range _Range, class... _Tail>(_Range&& __range, _Tail&&... __tail) static
     requires requires { //
       /**/ ranges::to<_Container>(std::forward<_Range>(__range), std::forward<_Tail>(__tail)...);

libcxx/test/libcxx/ranges/range.utility/range.utility.conv/to.verify.cpp

@@ -21,7 +21,6 @@ void test() {
   using member_func_ptr = decltype(&C::f);
   using member_ptr      = decltype(&C::member);
   using func_ptr        = decltype(&ff);
-  using func_t          = decltype(ff);
 
   struct R {
     int* begin() const { return nullptr; };
@@ -30,7 +29,6 @@ void test() {
     operator int() const { return 0; }
     operator int*() const { return nullptr; }
     operator func_ptr() const { return nullptr; }
-    operator void() const {}
     operator member_func_ptr() const { return nullptr; }
     operator member_ptr() const { return nullptr; }
     operator color() const { return color::red; }
@@ -49,31 +47,25 @@ void test() {
          std::ranges::to<
              func_ptr>()); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
 
-  (void)std::ranges::to<void>(
-      R{}); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
-  (void)(R{} | std::ranges::to<
-                   void>()); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
   (void)std::ranges::to<member_ptr>(
       R{}); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
   (void)(R{} |
          std::ranges::to<
              member_ptr>()); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
-  (void)std::ranges::to<member_func_ptr>(
+
+  (void)std::ranges::to<func_t>(
       R{}); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
-  (void)(R{} |
-         std::ranges::to<
-             member_func_ptr>()); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
-  (void)std::ranges::to<func_ptr>(
+  (void)(R{} | std::ranges::to<
+                   func_t>()); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
+
+  (void)std::ranges::to<void>(
       R{}); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
-  (void)(R{} |
-         std::ranges::to<
-             func_ptr>()); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
+  (void)(R{} | std::ranges::to<
+                   void>()); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
+  //expected-error-re@*:* {{static assertion failed{{.*}}ranges::to: unable to convert to the given container type.}}
+
   (void)std::ranges::to<color>(
       R{}); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
   (void)(R{} | std::ranges::to<
                    color>()); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
-  (void)std::ranges::to<func_t>(
-      R{}); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
-  (void)(R{} | std::ranges::to<
-                   func_t>()); //expected-error-re@*:* {{static assertion failed{{.*}}The target must be a class type}}
 }