https://github.com/dotnet/roslyn/issues/5032
There've always been rumblings here about removing nullable references from D, but that's a large break in backwards compatibility that we can't really afford at this point (outside some magic compiler switch). This C# proposal has some interesting ideas on how assisting the programmer in avoiding null pointer dereferencing can be balanced with backwards-compatibility concerns. I think there's some valuable stuff in here that could potentially be applied in D as well.