New @safe rule: defensive closures

[deadalnix]

On Friday, 27 May 2022 at 22:16:30 UTC, Steven Schveighoffer 
wrote:
> Currently, without DIP1000 enabled, this compiles, and if `bar` 
> squirrels away the array, you have a memory issue.
>

The fundamental problem here, is that proving whether it 
squirrels away or not is actually very difficult, and therefore, 
you really don't want to rely on this, especially if the end 
result is as drastic as making most functions closures.