preconditions and interfaces

[Alex]

On Sunday, 20 January 2019 at 15:39:49 UTC, Antonio Corbi wrote:
> Hi all,
>
> Playing with interfaces and preconditions in methods I get 
> strange results with dmd-2.0.84.0 but also with dmd-nightly. My 
> code is like this:
> -------------
> import std.stdio;
>
> interface Thing2D {
>   void width(int w)
>     in {
>       writeln("Thing2D.width contract w = ",w);
>       assert(w > 0);
>     }
> }
>
> class Line : Thing2D {
>   override void width(int w)
>     in {
>       writeln("Line.width contract w = ",w);
>       assert(w >= 0);
>     }
>   do {
>     writeln("Line.width: w = ", w);
>   }
> }
>
> void main() {
>   auto l = new Line;
>   l.width(-1);
> }
>
> ---------------
>
> 1) With dmd-2.084.0 I get:
> ./ifaceprecond
> Thing2D.width contract w = 2
> Line.width: w = -1
>
> 2) With dmd-nightly (as of today) I get random values for 
> interface's 'w':
> ./ifaceprecond
> Thing2D.width contract w = 647271536
> Line.width: w = -1
>
> I think this should be an error caught by the contract, isn't 
> it?
>
> Thx!
> Antonio

Seems to be something known...
https://forum.dlang.org/post/hficlieevnvzrnxywkzm@forum.dlang.org