Earlier quoted context omitted.
The idea that people occasionally throw around that C is more 'simple' and less 'complex' than C++ or Rust and therefore it leads to more maintainable or easy to understand code is, IMO, completely bogus . C is not simple, it is inept. There are so, so many bargain-bin features and capabilities that it just cannot do that it ends up creating much MORE complex code, not less complex code. I mean, just the pretense tha…
> Just making not literally every piece of data universally mutable? Not possible in C. Trivial in C++ and Rust, and it makes your programs SO much easier to reason about. And Rust is significantly better at this than C++ for the simple reason that mut is a modifier. I’ve lost track of how many times I’ve listened to Kate Gregory extol the virtues of const-ing all the things, but people still don’t systematically add…
Adding const to _function-local_ variables only really matters when you "leak" a pointer or ref, whether mutable or const, to a function or variable the compiler can't optimize away:
std::size_t sz = 4096;
const std::size_t &szRef = sz;
some_opaque_func(szRef);
if (sz != 4096) std::abort(); // cannot be optimized away unless sz is const
In other cases like RVO, adding const is actually detrimental as it prevents the move-constructor from being selected (likewise with the move assignment operator).
Rust _needs_ to have const by default due to its aliasing model ("only one mutable ref per object") and you can't have cheap bound checks without this. But that, too, is a tradeoff (some classes of programs are hard to code in Rust)