Bottom line is, if you are competent enough, you can be
successfull with D, just like you would be if you were using
C/C++. D's superior compile-time meta programming allows you to
express zero cost abstractions give you the edge that makes
things more enjoyable.
There are several open-source kernels written in D that are
proof of the above:
https://github.com/Vild/PowerNex
https://github.com/Bloodmanovski/Trinix
https://github.com/xomboverlord/xomb
Adam Ruppe has a chapter about bare-metal programming with D in
his Cookbook.
I do think D may be a perfectly valid real-time language. And
indeed, I believe that the GC is not an issue (you can disable
it, question solved).
However, is D a proper Embedded System language? I'm not pretty
sure it's there yet.
Plain C rules the world of embedded systems. All the RTES
programmers I've met are reluctant to even use C++.
If you cannot program a 16-bit PIC in D, then D will not replace
C at all (but is it meant to?).
The open-source kernels above are targeted at PC architecture.
I know some work have been done to make bare-metal OS targeted at
ARM. I don't know what's the state of those projects, and I'd
love to make my own once I have time (based on Rasberry Pi for
instance).
To validate D as a proper Real-Time Embedded System, one would
have to make a proper bare-metal OS a ARMv5 chip (for example).
Write your Interrupt Service Routines in assembly calling D
functions, program the MMU, the different hardware blocks (UART,
INTC, USB etc).
And the API of such an OS would benefit of the expressiveness
power of D (templates, traits UDA etc) and not just be a C-style
clone, with an efficiency similar to C (at least same CPU load).
