-preview=in might break code

[Andrei Alexandrescu]

On 10/5/20 4:42 AM, Mathias LANG wrote:
> 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

So now it's up to us to decide whether we want less of that or more of that.