William you have obviously read a lot about this stuff, but I suspect that you have scanned through a lot of stuff without fully understanding it.
Let me clarify some points: No C++ standard is compatible with Rust. You only bridge Rust and C++ because both let you use the C ABI. That is the common denominators. Whether gcc, clang or VC++ doesn't matter.
Btw it is called Qt and not QT. The latter is short for the Apple technology Quick Time. I know Qt very well. I've used it since it came out over 20 years ago. Even been on Job interview at Trolltech and got offered a job there.
Anyway Qt and Carbon isn't a problem. What the MOC compiler does is minor. It would not be that hard to do something similar for Carbon. Nor does anything prevent you from making some of the Code in plain C++. Most of your Qt code doesn't need to use the MOC compiler.
You are confused about LLVM and why it exists. LLVM has an intermediate representation for code which can be used between multiple stages of a compiler. That means people can independently make pieces in the compiler pipeline. It was an alternative to the monolithic design of gcc.
What you are thinking about is the fact that with LLVM you can write a compiler that generates low quality LLVM bytecode. The rest of the LLVM tools can then optimize this bytecode. That simplifies creation of new compilers as you don't need to be able to create highly optimized bytecode.
None of this has anything to do with Swift being written in C++. You are confused. Swift could be written in any language. Same applies to LLVM. The important thing about LLVM isn't its implementation language. Nor does Swift embed Objective-C.
Swift shares object model and runtime with Objective-C. A compiled Objective-C class looks like a native Swift class to Swift. That has nothing to do with LLVM by the way. LLVM bytecode is gone at that point. Once you turn LLVM bytecode into machine code there is no "memory" of LLVM having been involved. It is sharing an ABI which makes Objective-C and Swift highly compatible.
What you say about C++, Rust and the Linux kernel just shows your confusion William. You have read a bunch of stuff and gotten really excited that Rust is used in the Linux kernel but don't really understand what is going on. C++ isn't any more or less compatible with the Linux kernel than Rust.
The only difference between Rust and C++ in the Linux kernel is that Linus Torvalds okayed Rust and didn't okay C++. That is it!
Rust and C++ don't have interop other than indirectly through the C ABI. That is the whole point. That is the whole reason Carbon exists. Rust will never interface with C++ as well as Carbon has the potential for. Rust wasn't designed to be compatible with C++. If you make it highly compatible with C++ then its not going to be Rust anymore. It is going to be something similar to Carbon.
Look, I am not a fan of either C++ or Carbon. I think Rust looks like a better language than either one. But you are getting carried away with this extreme fanboyism. Carbon solves real problems. Personally I'd rather see people totally rewrite stuff to another language, but that is beside the point.
