Although there's not much concrete application (since a call to a @disabled is already statically checked) for now there is no way to know if a function is @disable.
dlang/dmd pull request #12093 "[dmd-cxx] Backport more recent traits to the C++ port" was merged into dmd-cxx:
- ccab65f15e2f28b4ab58a230aade08e6ce49be54 by Basile Burg:
[dmd-cxx] fix issue 18149 - Add a compiler trait to detect if a function is @disabled
https://github.com/dlang/dmd/pull/12093