> If you declared most of the mutable types const (and the use cases for a non-const unique_ptr are few) you can avoid most of these issues
Mutability in Rust is perfectly safe because of the static checks built into the type system – the compiler will catch you if you screw things up.
> you could never implement that without colossal backwards compatibility breakage
I cannot express how important immutability as default is. This prevents the issues that C++ has with folks forgetting to mark things as const. There is also lint that warns when locals are unnecessarily marked as mutable, which can catch some logic errors (I say that from experience).
Also note that I said 'immutability' not 'const'. Immutability is a far stronger invariant than const, and therefore is much safer. It could also lead to better compile-time optimisations in the future. I'm sure you know this, but just in case:
- const: you can't mutate it, but others possibly can
- immutable: nobody can mutate it
Mutability in Rust is perfectly safe because of the static checks built into the type system – the compiler will catch you if you screw things up.
> you could never implement that without colossal backwards compatibility breakage
I cannot express how important immutability as default is. This prevents the issues that C++ has with folks forgetting to mark things as const. There is also lint that warns when locals are unnecessarily marked as mutable, which can catch some logic errors (I say that from experience).
Also note that I said 'immutability' not 'const'. Immutability is a far stronger invariant than const, and therefore is much safer. It could also lead to better compile-time optimisations in the future. I'm sure you know this, but just in case:
- const: you can't mutate it, but others possibly can - immutable: nobody can mutate it