dip1000 + pure is a DEADLY COMBO

[Per Nordlöw]

On Wednesday, 12 May 2021 at 13:14:30 UTC, Dennis wrote:
> ### Why is this not fixed?
>
> Walter made a PR for fixing the behavior in dmd: (March 2020)
> https://github.com/dlang/dmd/pull/10924
>
> Later, aG0aep6G made a better fix: (November 2020)
> https://github.com/dlang/dmd/pull/12010

I vote for modifying this PR to emit a deprecation message for 
the new case not covered by phobos and many other projects.