Is NullableRef checked at compile time?

[ag0aep6g via Digitalmars-d-learn]

On 05/23/2016 08:10 PM, cy wrote:
> I was squinting at the std.typecons.NullableRef code and it _looks_ like
> isNull is only checked at runtime (and not checked at all in release
> mode!) but D has surprised me before in its ability to pre-calculate
> stuff during compilation.

NullableRef is little more than a plain pointer. In particular, it 
allows nulling the reference. Guarding against null dereferences doesn't 
seem to be on its agenda at all.

> I was thinking of using something like this:
>
> http://arsdnet.net/dcode/notnullsimplified.d
>
> ...which does the check once (during runtime) but after that it's
> compile-time verified not to have a null pointer. (Sort of like C++
> references!) I think using NullableRef instead would have every instance
> of getting the pointer perform the check at runtime, even if it has
> already been verified as not null. That's correct, right? Yes I know,
> premature optimization etc, but I was just curious if a NotNull template
> might be a stronger declaration of a pointer's nullness.

Notice the different name. The goals of NotNull and NullableRef seem to 
be entirely different.

Also note that NotNull uses `assert` for the check, too. So there's no 
check with -release either. Can easily change that to `enforce`, of course.