I sorely wish CSP was enforced in any way by Go, but it's not. The only thing which arguably makes Go more "CSP-y" than, say, C++ is that it comes with a decent built-in concurrent queue and some syntax sugar. Goroutines have full mutable access to all the variables in their scope, and lots of Go code ends up being your good old mutex hell -- just more of it, since threads are so easy to create.

I think something way more radical than "C++ threads but with a built-in concurrent queue" is needed. If the default was to share nothing, and any shared memory had to be explicitly shared somehow, that would be a great step in the right direction. Maybe the compiler could even check that explicitly-shared variables are protected by a mutex; something like how Rust mutexes "own" the things they're protecting and you can't access the underlying object without having the lock.