forked from mpusz/mp-units
Removing the `WeaklyRegular` requirement from the `Scalar`, `Complex`, and `Vector` concepts seems to address compiler crashes or long compilation times with apple-clang included in Xcode 15. I thought I had previously tried removing the `WeaklyRegular` requirement and it had not solved the problem but either I made a mistake with this test or some other changes after rebasing this work changed the situation.