[D1] capitalize cannot be interpreted at CT

[Don]

Ellery Newcomer wrote:
> On 07/21/2010 09:09 PM, strtr wrote:
>> Could somebody please explain this error to me.
> 
> evidently ctfe can't eat
> 
> foreach(i, dchar d; s){
> }
> 
> Bleach. Make sure it's in bugzilla.

CTFE currently doesn't work on *any* functions which are implemented in 
druntime, because it doesn't have access to their source code.