What are the unused but useful feature you know in D?

[Moritz Maxeiner via Digitalmars-d]

On Monday, 26 June 2017 at 18:47:18 UTC, Random D user wrote:
> Anyway, I think we could just have a compile time switch for 
> defaults.

Imagine having n libraries with pairwise different required 
defaults used in your application. Say goodbye to combined 
compilation, hello n separate required compiler invocations.

> Since some projects want to have pure, @safe, immutable by 
> default, but others want to have @system @nogc. And no one 
> wants write attributes more than they have to.

That's why most of what I do is in templates, so the compiler 
infers them for me, anyway.

>
> Also I think @safe is a little bit broken (because of @trusted 
> and even the very pros (d-devs) seem to get @trusted wrong on a 
> regular basis (at least that's my perception)). Just bite the 
> bullet and use Rust if you want to be actually safe.

Except Rust is in exactly the same boat as D, because the same 
issues that apply to `@trusted` apply to `unsafe`, as well.

>
> Which reminds me that it would be nice to group attributes as 
> well.
> Something like this:
> alias @apiStrict = @safe immutable pure
>
> int foo() @apiStrict
> {
>   return 1;
> }

That would be useful.