Better diagnostics for null classes dereferencing

[kdevel]

On Tuesday, 10 July 2018 at 22:31:54 UTC, Adam D. Ruppe wrote:
> Turn off rtTrapExceptions....
>
> though the command line switch PR is STILL NOT MERGED
>
> https://github.com/dlang/druntime/pull/2035

    extern (C) __gshared bool rt_trapExceptions;
    static this ()
    {
       rt_trapExceptions = false;
    }

plus

    -L-zmuldefs

is required for linking. It works. But why is that -zmuldefs 
linker option required? The "double extern" version

    extern extern (C) __gshared bool rt_trapExceptions;

compiles and links but does not behave seem to set the same 
variable.