-preview=in might break code

[Iain Buclaw]

On Monday, 5 October 2020 at 07:55:57 UTC, Walter Bright wrote:
> On 10/4/2020 7:19 AM, Iain Buclaw wrote:
>> I've also skimmed past a passing concern that the ABI between 
>> compilers would be different.  Well, let me rest assure you 
>> that DMD, GDC and LDC have never been compatible in the first 
>> place, so there's no point worrying about that now.
>
> The problem is not dmd compiled code calling gdc/ldc compiled 
> code. The problem is code that works with one compiler fails 
> with another, because the "to ref or not to ref" decision is 
> *implementation defined*.

Granted this is a new preview feature, I can only see it being 
healthy if each vendor tries something different and reports back 
on how much success they had with it.

So let other vendors implement as they interpret the spec, and we 
can converge later based on success/failings of our given 
decisions.  I imagine we are 10 releases of DMD away from even 
considering whether or not this should come out of `-preview`.