[Dlang-internal] Drive-by feature pull requests

[Nick Treleaven]

Recently there have been a number of pull requests that add a 
significant feature to D, with no previous design discussion. I'm 
talking about features that quite clearly need a DIP. Some of 
these did then get a forum DIP post. But then you have some 
design discussion in the PR and some on the forum, and it's 
harder to track which feedback has been addressed by the 
submitter.

This is also undesirable because pull requests should mainly be 
about reviewing the implementation. Pull request comments are not 
properly threaded and are harder to follow, and they get in the 
way of implementation discussion and reviewing. Design discussion 
should happen primarily on the forum, or in other places than a 
PR.

How can we stop this? When anyone sees this happen and there is 
no disclaimer in the PR, anyone should add a warning not to 
critique the design in the PR and to open a forum thread instead. 
Possibly a threat to delete subsequent design discussion if the 
warning is ignored may be useful. This still relies on the 
warning being given soon after the PR is submitted. But it could 
help inform people not to do this.