fake RefCounted for CTFE?

[Steven Schveighoffer]

On 6/15/20 8:23 PM, Steven Schveighoffer wrote:
> On 6/15/20 5:39 PM, Timon Gehr wrote:
>> On 15.06.20 23:18, Steven Schveighoffer wrote:
>>> I'm doing some stuff with RefCounted for a factory-like expression, 
>>> where I expect the factory harnesses are going to be very 
>>> short-lived. However, these don't work at CTFE (because malloc/etc 
>>> aren't available).
>>>
>>> Would it make sense for RefCounted to turn into GC for CTFE mode? 
>>> That is, if RefCounted is used during CTFE, it just allocates on the 
>>> GC heap and doesn't actually do ref counting. The end result will be 
>>> a ref counted struct that somehow is flagged that it's never going 
>>> away (and it shouldn't, if it's generated at compile time).
>>>
>>> Then you could use functions that return RefCounted items as static 
>>> initializers, or use libraries that use RefCounted at compile time 
>>> without issues.
>>>
>>> What do you think?
>>
>> I think it should work in CTFE, but it cannot break @nogc.
> 
> Damn you're right. I can't think of a good way around that.
> 
> All I can think of is a specialized function which allocates only in 
> CTFE, and the compiler pretends it can be @nogc.

Another suggestion I found on the issue tracker:

https://issues.dlang.org/show_bug.cgi?id=18119

-Steve