[Issue 20000] Casting to interfaces arbitrarily disallowed in @safe code

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20000

Basile-z <b2.temp at gmx.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |b2.temp at gmx.com

--- Comment #1 from Basile-z <b2.temp at gmx.com> ---
This is more subtle:

---
module runnable;

import std.stdio;

extern(C++) interface Foo
{
    void foo();
}

extern(C++) interface Bar
{
    void bar();
}

extern(C++) class C1 : Foo
{
    void foo(){writeln("do I look like a Bar !!");}
}

void main(string[] args)
{
    (cast(Bar) new C1).bar();
}
---

With the C++ compat this is clearly not @safe. The fix would have to check
carefully these details.

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