Vision for the D language - stabilizing complexity?

[Jesse Phillips via Digitalmars-d]

On Thursday, 14 July 2016 at 16:47:20 UTC, Ola Fosheim Grøstad 
wrote:
> On Thursday, 14 July 2016 at 16:17:19 UTC, Jesse Phillips wrote:
>> I still haven't found someone who can explain how C++ can 
>> define the behavior of modifying a variable after casting away 
>> const.
>
> C++ is locked down in a mine-field of backward compatibility 
> issues and a need to interface with C verbatim (directly 
> including C header files where const parameters might lack the 
> const modifier).
>
> D does not work with C header files and can redefine the 
> interfaces to fit D semantics in C bindings...

That doesn't explain how you can define the behavior:

     void foo(int const* p) {
         *(const_cast<int*>(p)) = 3;
     }

Does 'p' get modified or is the program going to crash or 
something else? Please define it for me. C++ says: You can't 
modify the location pointed to by 'p' from 'p', using const_cast 
on 'p' you'll either get undefined behavior or it will modify the 
location 'p' points to. So it is defined to either be undefined 
or modify the location 'p' refers to. The language isn't able to 
tell you what will happen so how can it define the behavior?