I have wanted to configure targets in such a way that I can pass -stdc++17 as a default value but remove this flag if a consumer wants to use a different version. Using --copt is insufficient as it leads to targets being un-buildable unless consumers specify this on the command line or in their .bazelrc files which can be confusing or not feasible.

Would it be reasonable to define some cxx_standard constraints somewhere within rules_cc that's backed by a string flag such that users can specify on the command line or via a transition what version to use but would otherwise allow maintainers to set meaningful defaults that don't hinder folks who want to use different versions?