Missing/desired feature in C?

Question

I couldn't find another topic about this. I apologize if it's a duplicate.

So, what feature do you miss in the C language?

Please, keep in mind the design principles (Trust the programmer, Keep the language small and simple, Provide only one way to do an operation, etc..) so don't come out with "Garbage collection would be awesome!" and stuff like that

Personally i would really like namespaces with public/private labels.

namespace Foo {
   public:
       void bar(int*, float);
   ...
   private:
       int baz(int);
   ...
}

int main(void) {
   ...
   Foo::bar(&a, b);
   ...
}

I think it would be a good thing to standardize the bunch of "design patterns" used to emulate namespaces (for instance: Namespaces in C).