Returning reference: why this works?

[Denis Feklushkin]

On Wednesday, 13 March 2019 at 21:04:01 UTC, Johan Engelen wrote:
> On Wednesday, 13 March 2019 at 20:57:13 UTC, Denis Feklushkin 
> wrote:
>> import std.stdio;
>>
>> struct S { int x; }
>>
>> ref S func1(ref S i) // i is reference
>> {
>>     return i;
>> }
>>
>> ref S func2(S i) // i is not reference
>> {
>>   return func1(i); // Works! Possibility to return reference 
>> to local object i?
>
> Indeed, you're invoking UB here. With compiler flag `-dip25` 
> that code no longer compiles.
>
> -Johan

Oh, very unexpected! Thank you very much!