Unused druntime code: Barrier, ReadWriteMutex, Condition

[Richard (Rikki) Andrew Cattermole]

On 16/06/2026 8:15 PM, Denis Feklushkin wrote:
> On Monday, 15 June 2026 at 23:50:01 UTC, Richard (Rikki) Andrew 
> Cattermole wrote:
> 
>>> The attempt to use standard Semaphore and Mutex in ondition 
>>> implementation failed because the current Condition semantics 
>>> requires @nogc, but Mutex and Semaphore are classes and 
>>> std.typecons.scoped isn't available in druntime.
>>
>> The implementation can be extracted into a package struct.
> 
> This leads to duplication of code what already available in 
> `std.typecons.scoped`

No.

I did not suggest anything to do with scoped.

All of the state and function calls to make it platform independent does 
not need to live in a class. It can live in a struct instead and then be 
called into.

```d
class Thing {
	private Thing2 thing2;

	void call() => thing2.call();
}

package:

struct Thing2 {
	void* state;

	void call() {
	}
}
```

>> Nothing needs to break to fix this.
> 
> Why you use "break" to describe this?
> I do not propose break anything: I propose to add `public import` from 
> `std.concurrency.rwmutex` (etc) into `core.sync.rwmutex` module with 
> appropriate deprecation messages.

Druntime cannot import phobos.

Phobos depends upon druntime.

Binary loading is acyclic, not cyclic.

No PR that tries to do this will be merged.