On 29.08.2018 03:59, Walter Bright wrote:
There's been some talk of adding a "mutable" qualifier for fields, which would stop the transitivity of const at that point. But it has problems, such as what happens with opaque types. The compiler can no longer check them, and hence will have to assume they contain mutable members.
This is a misunderstanding. The __mutable DIP will define the set of allowed program rewrites based on const/immutable/pure. Then code that uses __mutable must remain correct when they are applied. This achieves two things: it clearly defines the semantics of const/immutable/pure and (the possibility of) __mutable will not be an optimization blocker.
I'll get back to this once I have finished the tuple DIP implementation.
