Not a compiler bug.

[mw]

On Thursday, 13 August 2020 at 09:25:07 UTC, John Colvin wrote:

> Personally I would love to be able to disallow implicit 
> signed-to-unsigned conversions in almost all cases, but that 
> would be a big breaking change.

At least I want a warning message, even with a turn-on 
command-line switch is fine, I personally will turn it on all the 
time, silently performing this conversions is horrible.

I spent half of the night yesterday to trace down the issue.

https://run.dlang.io/is/je8L4r
==================================
import std.algorithm;
import std.stdio;

void main() {
   long[] a = [-5000, 0];
   long   c = sum(a) / a.length;
   writeln(c);   // output 9223372036854773308
}
==================================


In contrast, there was a compiler warning message for loop index
https://run.dlang.io/is/4Sqc5n
onlineapp.d(4): Deprecation: foreach: loop index implicitly 
converted from size_t to int