On 11/01/2016 06:52 PM, Nordlöw wrote:
Should I always, when possible, prefer `immutable` over `const`?
I'd say: prefer immutable.
And does `immutable` increase the possibility of the compiler doing optimizations, such as common subexpression elimination? Or can the compiler infer `const` declarations to also be `immutable`?
A `const int x = 42;` is effectively immutable, but its type is const(int), not immutable(int). A compiler may be smart enough to treat it as immutable with regards to optimizations, but I wouldn't expect dmd to be that smart, or only in very simple cases. ldc and gdc are probably better at it.
However, for function overloads and such the compiler must consider the type, not any additional information it has about the data. So if some function has an optimized overload for immutable, that can only be taken when you type out "immutable".
