Make -preview=intpromote not suck

[Ola Fosheim Grøstad]

On Wednesday, 28 October 2020 at 17:34:10 UTC, Steven 
Schveighoffer wrote:
> That ship may have sailed though. The goal is also different. I 
> want to *avoid* breaking existing code, except in the case 
> where it differs from the expected behavior. The exception in 
> all of this is -int.min, which is still not going to work right.


Just add a switch that compiles with runtime overflow checks for 
signed integers (that prints file and line number when it traps). 
Then run it on available codebases and get an impression of where 
the issues are.