Appending immutable char implicit cast to int, bug or feature?

[Ali Çehreli]

On 12/05/2012 09:30 AM, ixid wrote:
> This is simple code to create all genetic combinations from two organisms.
>
> string[] mixGenes(string a, string b) {
> string[] result;
>
> foreach(i;0..2)
> foreach(j;0..2)
> foreach(k;2..4)
> foreach(m;2..4)
> result ~= [a[i]] ~ [b[j]] ~ [a[k]] ~ [b[m]];
>
> return result;
> }
>
> This works, however when I remove the brackets:
>
> result ~= a[i] ~ b[j] ~ a[k] ~ b[m];
>
> I get the error:
>
> Error: incompatible types for ((cast(int)a[cast(uint)i]) ~
> (cast(int)b[cast(uint)j])): 'int' and 'int'
>
> Why, when trying to append immutable chars to make a string, has it
> decided to implicitly cast them to int?

I don't know where that cast occurs but I wanted to state the obvious: 
Operator ~ is defined only for arrays.

Ali