[OT] The Usual Arithmetic Confusions

[bachmeier]

On Friday, 28 January 2022 at 02:15:51 UTC, Paul Backus wrote:
> Unfortunately, this is also one of the areas of D that comes 
> directly from C, so D programmers have to watch out for these 
> as well.

Here's a lovely one I wrote about yesterday in Learn:

```
import std.conv, std.range, std.stdio;

void main() {
	writeln(iota(5, 0, -1));
	writeln(iota(5, -1, -1));
	writeln(iota(5.to!uint, -1, -1));
	writeln(iota(5.to!uint, 0, -1));
	writeln(-1.to!uint);
	auto z = -1;
	writeln(z.to!uint);
}
```

Which delivers the following output:

```
[5, 4, 3, 2, 1]
[5, 4, 3, 2, 1, 0]
[]
[5, 4, 3, 2, 1]
4294967295
std.conv.ConvOverflowException@/usr/include/dmd/phobos/std/conv.d(567): Conversion negative overflow
----------------
??:? pure @safe bool std.exception.enforce!(bool).enforce(bool, 
lazy object.Throwable) [0x555fe1c5c946]
??:? pure @safe uint std.conv.toImpl!(uint, int).toImpl(int) 
[0x555fe1c6f1ff]
??:? pure @safe uint std.conv.to!(uint).to!(int).to(int) 
[0x555fe1c6f1d0]
??:? _Dmain [0x555fe1c5594c]
```

All I wanted was a function that iterates through the elements of 
an array starting at the end. The only time you have a problem is 
if you want to include the first element of the array.

A simple solution is to add a `-scottmeyers` switch that retains 
full compatibility with C, but sets the default as a language 
that is productive.