>careful when dealing with generics / operator overloading

In C++, you can't overload operators for built-in types and template parameters are normally constrained:

  auto f(std::integral auto x) noexcept
  {
      return x+x;
  }

But yes, writing C++ templates that work with wide range of types takes some thinking and operator overloading adds to the mental load (or reduces it, when used sparingly and properly).

>"Operations on basic types" can now invoke UB

They always could. I don't want this conversation to become about Rust vs. C++, I'd gladly use Rust when where is appropriate task.

>needs a concrete example to discuss

Write a new post when you come up with a bunch of good examples)