fake RefCounted for CTFE?

[tsbockman]

On Monday, 15 June 2020 at 21:18:23 UTC, Steven Schveighoffer 
wrote:
> 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. 
> ...
> What do you think?

Ref counting isn't only for memory management - sometimes it's 
used to ensure that a value's destructor will run at a logical 
point in time. Using the garbage collector during CTFE instead of 
malloc/free or whatever should be fine, but some thought would 
need to be put into whether there are any other valid uses of 
destructors during CTFE.

The requirement that CTFE functions be pure at least forbids 
*most* other uses of destructors - for example, there is no need 
to close a file in CTFE, since you can't open one to begin with.

But, does D's weak purity provably forbid *all* other valid uses 
of destructors? Making a bad assumption here could break code in 
really ugly and confusing ways, since CTFE is often triggered 
implicitly without any deliberate intent on the part of the 
programmer.