Why is my @pure function @system when placed in a struct?

[Stefan Koch]

On Wednesday, 27 February 2019 at 17:23:21 UTC, Q. Schroll wrote:
> I have a template function `fImpl` I whish to instantiate 
> manually using the new name `f`. Reason is simple: `f` should 
> not be a template, but overloading it makes it easier that way.
> Nothing's more simple in D:
>
> [...]

the struct gets drawn into your delegate-context.
and I guess that taints  the function.