dmd foreach loops throw exceptions on invalid UTF sequences, use replacementDchar instead

[Andrei Alexandrescu]

On 2021-11-05 10:22, jfondren wrote:
> 3. a compile-time error (also proposed in the thread)

Speaking of which, I was thinking std2x should simply reject mixed-sign 
min and max during compilation instead of cleverly figuring out the 
"right" comparison. Now we have signed() and unsigned() that make it 
trivial for the user to steer min and max toward doing the right thing, 
and it's clearer too.