opSlice Bug?

[Ali Çehreli]

On 11/29/2012 08:15 AM, Namespace wrote:
> Why I have to write
> arr2[] += arr[][]
> instead of
> arr2[] += arr[]
> ? Bug or 'feature'? :P
>
> Code:
> http://dpaste.dzfl.pl/4c732f4c

Apparently, the array-wise operations require the following syntax:

     a[] += b[];

In other words, the compiler wants to see [] on the right-hand side as 
well. The following does not work with the same error message that you get:

     int[] a, b;
     a[] += b;

Error: invalid array operation a[] += b (did you forget a [] ?)

It is the same in your case. You have a function that returns a slice 
but the compiler still wants to see [] on the rigth-hand side:

int[] foo()
{
     int[] b;
     return b;
}

void main()
{
     int[] a;
     a[] += foo();    // <-- Same compilation error
}

That's why you need to put the [] after it:

     a[] += foo()[];

I think it is just the requirement of the syntax. (?)

Ali