The problem is, outside Ada and Rust, there isn't much of anything that's maintained because people stayed rejecting anything but C. I will post this on Ada so you can see (a) a nice survey of problems that show up and (b) how it systematically counters them.

http://www.adacore.com/uploads/technical-papers/SafeSecureAd...

The best candidates for simpler ones were Wirth-like languages, esp Modula-3. I used to recommend Delphi as it was a Pascal alternative to Visual C++ whose apps rarely crashed. Free Pascal succeed w/ Lazaurus IDE succeeded it w/ tons of hardware support. Component Pascal w/ Blackbox is still active AFAIK. D is quite active.

Some Modula-2 benefits https://news.ycombinator.com/item?id=9640126

Modula-3 features https://en.wikipedia.org/wiki/Modula-3

Note: Fast to compile, fast to run, easy to read, easy to integrate, optional GC, optional OOP... why we need C and C++ again? Outside legacy systems...

Free Pascal http://www.freepascal.org/

Component Pascal https://en.wikipedia.org/wiki/Component_Pascal

D language (C/C++ successor) https://en.wikipedia.org/wiki/D_%28programming_language%29

Julia http://julialang.org/

Note: It's a language for scientific programming but it's worth considering given speed and C support.

On functional side, people are writing OS's in Haskell, Ocaml, and so on. OcaPic put Ocaml on 8-bitters. ATS Language was used for drivers and 8-bitters. RED/System is like LISP w/out parenthesis for system programming with ability to make DSL's. Any such language can have safety checks built in or output something for analysis. So, even functional languages are performing acceptably in places where C used to be required. Just need more people investing into any trouble spots.

Someone could also pick up the code of Popcorn, Cyclone, or another safer C to develop it. Cyclone is worth linking to as it was so clever:

https://en.wikipedia.org/wiki/Cyclone_%28programming_languag...

Just gotta maintain the front-end. Ivory language from Galois is still maintained & extracts to C. Tools like Softbound+CETS will autotransform your code to safety at a 10-40% performance hit. A typed assembler language like TALx86 or custom one from Hyde's HLA would give you lower level than C with more safety ironically. So, many options for OSS to build on with some like Pascals having mature tooling.

EDIT: Just remembered the Pike programming language used in Roxen web & app servers as a C alternative. They're FAST. So, do google it.