Bug in countUntil?

[Jonathan M Davis]

On Friday, October 12, 2012 21:02:47 monarch_dodra wrote:
> I was looking in countUntil to fix another issue, and I think the
> string support is broken
> 
> This program:
> //----
> import std.algorithm;
> import std.stdio;
> 
> void main()
> {
>      "日本語".countUntil('本').writeln();
> }
> //----
> 
> Will produce "3".
> 
> ...
> 
> I'd have straight up said it was a bug, but the implementation
> goes out of its way to special case narrow strings, when the
> default implementation would have produced the right result
> anyway. So I was thinking it is somehow by design...?
> 
> Am I missing something, or is it just implementation sillyness?

Many algorithms special case narrow strings for efficiency. However, in this 
case, it looks just plain wrong. countUntil is supposed to return the number 
of elements (i.e. code points in this case), but it looks like it's returning 
the number of code units. So, I'd say that it's definitely wrong. If you want 
code units, then use std.string.indexOf. countUntil is supposed to return the 
number of code points.

- Jonathan M Davis