> Therefore, the answer to the question of, say, “what is a valid C++14 program?” changes over time, up until the publication of C++17, and so forth. In practice, the situation is a bit more complicated when compiler vendors offer conformance modes for specific language revisions (e.g. -std=c++11, -std=c++17). Vendors may consider defect resolutions to apply to any historic revision that contains the defect (whereas ISO considers only the most recent publication as the Standard).

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p213...

Feel free to think I am only doing FUD, and coming from C++ side I am clueless about how editions will fare in the future.