It supports neither templates nor ADL, the two of my examples.

In fact the doc says,

> Being 100% compatible with C++ means more or less adding a fully functional C++ compiler front end to D. Anecdotal evidence suggests that writing such is a minimum of a 10 man-year project, essentially making a D compiler with such capability unimplementable.

It then goes on to describe the pragmatic approach that doesn't allow full compatibility:

> D takes a pragmatic approach that assumes a couple modest accommodations can solve a significant chunk of the problem:

> matching C++ name mangling conventions

> matching C++ function calling conventions

> matching C++ virtual function table layout for single inheritance

Can you see how limited this subset of interoperable API is?

> matching C++ name mangling conventions

> matching C++ function calling conventions

> matching C++ virtual function table layout for single inheritance

Basically COM? Which is not surprising as it was designed as an OO native FFI.

And UWP improves on it, giving more C++ features across the ABI, basically what .NET v1.0 should have been all along.

I didn't state it supports 100% compatibility, and it is still better than being stuck with an OS ABI from the 70s, that is only meaningful when the underlying OS is written in C anyway.