(since C++20) [__has_cpp_attribute](https://en.cppreference.com/w/cpp/feature_test#Attributes) expressions, which detects whether a given attribute token is supported and its supported version. https://en.cppreference.com/w/cpp/preprocessor/conditional
(since C++20) __has_cpp_attribute expressions, which detects whether a given attribute token is supported and its supported version.
https://en.cppreference.com/w/cpp/preprocessor/conditional