-preview=in might break code

[Mathias LANG]

On Monday, 5 October 2020 at 08:34:37 UTC, Iain Buclaw wrote:
> 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*.
>
> Furthermore, NRVO is implementation defined, which results in 
> the same dmd/gdc/ldc making different decisions for "to ref or 
> not to ref", and yet I see no one complaining about that.

I cannot resist the bait: 
https://issues.dlang.org/show_bug.cgi?id=20752