Comment Re:There is already a safe subset of C++ (Score 1) 30
Ish.
I would not trust C++ for safety-critical work as MISRA can only limit features, it can't add support for contracts.
There have been other dialects of C++ - Aspect-Oriented C++ and Feature-Oriented C++ being the two that I monitored closely. You can't really do either by using subsetting, regardless of mechanism.
IMHO, it might be easier to reverse the problem. Instead of having specific subsets for specific tasks, where you drill down to the subset you want, have specific subsets for specific mechanisms where you build up to the feature set you need.