D's only runtime memory safety feature is array bounds checking. (The same as Rust, I believe.) The rest is compile time.

D's compile time memory safety focusses on:

1. @safe and @system code

2. disallowing unsafe pointer operations

3. safe alternatives to pointers

4. controlling escaping of pointers

5. controlling the scope of addresses

Rust has other runtime memory safety checking, like RefCell.

D's compiler was never "closed source" if by that you mean "source not visible". It had a weird non-open source license for a long time, but the source has always been visible.

The weird license did use to scare me away, but that's very much a thing of the past now and now it has a standard free license.

https://news.ycombinator.com/item?id=14060846

I don't think D's features are any less exciting than Rust's, but Rust has had a lot of RESF backed by Mozilla.

Source code being visible doesn't make it open source. It had a personal-use-only license, which isn't a valid OSSI license (which is what makes something open source).

That's why I qualified it with "if that's what you mean by closed source". I don't know if all source is either open or closed and anything that isn't OSI-approved is closed. I don't think that's what people usually mean by "closed source".

I also freely granted that dmd's ad-hoc license wasn't open source despite having visible source.

> D had a closed source reference compiler for a long time, and didn't have any major backers.

In addition, wasn't there for a while two separate and incomparable versions of the standard library that fragmented the community?

That was 9 years ago and the second is no longer maintained (for about 2 years at this point).

That's fair, I suspected that people who knew more about this stuff had a reason.

Compiling slower than C++ is not exciting.

just to be clear, p0nce is referring to rust's compile time. D is known to have very fast compile times (unless you are doing very template heavy meta programming..)