slight rework

clang on linux doesn't believe field.name() can be constexpr, so
fall back to Field::name() when constexpr is required.

README.md

@@ -301,7 +301,6 @@ const auto view = rfl::to_view(lisa);
 
 view.apply([](const auto& f) {
   // f is a an rfl::Field pointing to the original field.
-  // f.name() is a compile-time constant.
   std::cout << f.name() << ": " << rfl::json::write(*f.value()) << std::endl;
 });
 ```

docs/named_tuple.md

@@ -102,11 +102,13 @@ auto person = rfl::Field<"first_name", std::string>("Bart") *
               rfl::Field<"last_name", std::string>("Simpson");
 
 person.apply([](const auto& f) {
-  constexpr auto field_name = f.name();
+  auto field_name = f.name();
   const auto& value = *f.value();
 });
 
 person.apply([]<typename Field>(Field& f) {
+  // The field name can also be obtained as a compile-time constant.
+  constexpr auto field_name = Field::name();
   using field_pointer_type = typename Field::Type;
   field_pointer_type* value = f.value();
 });

tests/json/test_view.cpp

@@ -34,15 +34,15 @@ void test() {
 
   view.apply([]<typename Field>(const Field& field) {
     using field_type = std::remove_pointer_t<typename Field::Type>;
-    if constexpr (field.name() == "age") {
+    if constexpr (Field::name() == "age") {
       static_assert(std::is_same_v<field_type, int>);
     } else {
       static_assert(std::is_same_v<field_type, std::string>);
     }
   });
 
-  rfl::to_view(lisa).apply([](auto&& field) {
-    if constexpr (field.name() == "first_name") {
+  rfl::to_view(lisa).apply([](auto field) {
+    if constexpr (decltype(field)::name() == "first_name") {
       *field.value() = "Bart";
     }
   });