> What is mess in C++?

Just a couple examples:

How do you make a shallow copy of an object in C++, how do you do the same thing in C? Knowing I can just memcpy _any_ struct in C and have a valid shallow copy is pretty huge.

How do you create a stable ABI in C++? How do you make one in C? In C, knowing that all my exported functions will mostly just work and be stable as long as I don’t change the interface is also huge and allows you to create cross language bindings pretty trivially.

> How do you make a shallow copy of an object in C++

Shallow copies aren't generally possible for classes storing something indirectly, since it violates ownership semantics. That's not how things are done in C++.. Operator = is usually used for making copies, which is optimized to memcpy for POD structures, but for something more complex may perform extra work for doing an actual deep copy.

> How do you create a stable ABI in C++

It's a complex topic. Basic ABI for calling functions is identical to C. But one need to keep in mind, that type layouts and internal implementations of library types (like containers) may differ from implementation to implementation and from version to version.

> knowing that all my exported functions will mostly just work and be stable as long as I don’t change the interface

Nothing prevents you doing this in C++. You can have C-style external interface and use all goods of C++ internally.

You can’t necessarily do that in C either, it depends on if your object is in a container that relies on pointer stability. Intrusive linked lists are common in C and they get broken by this, for example.