`@safe` by default. What about `@pure` and `immutable` by default?

[Andrei Alexandrescu]

On 4/18/19 2:33 PM, Eugene Wissner wrote:
> On Thursday, 18 April 2019 at 14:52:53 UTC, Jonathan M Davis wrote:
>> pure means that the function does not access mutable, global state 
>> except via the function's arguments. That's it. nd the compiler _is_ 
>> able to do stuff with that and does so right now.
> 
> That compiler actually does something with pure is new to me. So I was 
> wrong here.

There's a lively discussion at 
https://github.com/dlang/dlang.org/pull/2627. Specialists welcome.