I agree, in principle. But reading over this document, the changes can be made in an incremental fashion. And with far less impact than switching to using C++ just for these (assuming equivalents exist) features.

switching to c++ can also be done in an incremental fashion.

Yes, but not quite as trivially as:

  Enable extension
  Add `checked` to array declarations. (for the simplest
  case they've implemented).

Converting to C++ also means making sure you have `extern "C"` in your function declarations to get around C++'s name mangling when calling C libraries. Among other, potential, source level changes. Or, similarly, making sure your C (now C++) library can be called correctly by C projects that depended on it.

I'm not sold on this project as we haven't seen any results of course, but the approach is simpler than switching to C++.

There are also some nice C99 syntax features like compound literals that may not be supported by your C++ compiler.

since many C programs will have simple array types like that, this addition is mostly syntactic.