ADA
I was at ARM TechCon last week, and I finally figured out why Ada (and other langauges) have no popularity in embedded...
There was this big trade show, and lots of vendors.
IAR and Greenhills were there with their C compilers (plus ARM themselves with Keil, and Atmel/etc with gcc.)
Assorted vendors offering specialized debugging tools. For C.
Assorted vendors with networking stacks: USB, Bluetooth, TCP/IP, assorted random wireless protoocols. In C.
Assorted vendors with operating systems: mBed. Micrium. MyNewt. Zephyr. All in C.
And, on the edge of the room, there was AdaCore with their Ada Compiler... All by themselves.
I didn't see any "D", and I'm not sure about C vs C++. There might have been some Java. No C#, AFAICT. After C the most "interest" was in the BBC Micro Bit, which has its own graphical programming language (for kids, you know.)
Most of the realistic alternatives to C in the embedded space are just languages. C is ... multiple
industries!