-preview switches

[Johan]

On Wednesday, 1 April 2020 at 14:26:15 UTC, Atila Neves wrote:
>
> I think the right way to nudge D programmers to transition to 
> where we can turn -preview into -revert is to issue deprecation 
> messages for a while. Nothing like a noisy build to get people 
> to file issues on github (or even better, PRs) to get this 
> fixed.

Please note that deprecation messages are effectively errors in a 
build environment with -de (i.e. Weka). In that case the only 
workable compilation is to use the new way (i.e. with preview 
switch). Especially due to deprecation/error messages in 
speculative code, this can be annoying to deal with.
What is nice about _not_ showing deprecation messages and instead 
having only -preview, is that it is easier to switch to a new 
compiler (which always creates a ton of work already). And then 
slowly one can enable the preview options to get ready for the 
future. I do think that putting a date on certain things will 
help create some urgency to start future proofing code.

-Johan