[Issue 24793] Allow implicit conversion of const pointers to void*

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24793

--- Comment #1 from anonymous4 <dfj1esp02 at sneakemail.com> ---
Any pimpl pattern is affected by this.
---
struct Console
{
    GtkButton* btn;

    void write(string s) const
    {
        g_signal_connect_data(cast(GtkButton*)btn, "clicked", &onClick);
    }
}
---

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