Unused druntime code: Barrier, ReadWriteMutex, Condition

[Richard (Rikki) Andrew Cattermole]

On 16/06/2026 2:23 AM, Denis Feklushkin wrote:
> On Monday, 15 June 2026 at 10:35:39 UTC, Denis Feklushkin wrote:
>> On Monday, 15 June 2026 at 09:41:00 UTC, Denis Feklushkin wrote:
>>
>>> Most likely, these primitives do not exist in any OS - they are too 
>>> high-level and can be implemented on the basis of "more primitive" 
>>> primitives. (Posix implementation just provides convient wrapper, I 
>>> think)
>>
>> It is possible make PR on this base which will satisfy everyone. 
>> However, I'll wait for information about Windows (see previous message).
> 
> 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.

Nothing needs to break to fix this.

> This is another argument for moving this code to Phobos

There is no valid argument here.

To move it requires breaking user code, and that is not an option.