mixin alias

[Jarrett Billingsley]

"Derek Parnell" <derek at psych.ward> wrote in message 
news:jnak6l8ihhe1.k3tzm3in813z.dlg at 40tude.net...
> Is there any reason why the alias template parameter cannot be a literal?
>
>
> template Foo(alias b) {
>   int X = b;
> }
>
> void main() {
>  int y = 4;
>  mixin Foo!(y);  // This is okay
>  mixin Foo!(4);  // This fails to compile
>   // "mixin Foo!(4) does not match any template declaration"
> }
>

This is correct.  You can only alias things that have names; the number 3 
does not have a name.

What's weird is that:

template Foo(alias b)
{
    int X = b;
}

template Foo(int b)
{
    int X = b;
}

void main()
{
    int y = 4;
    mixin Foo!(4); // OK
    // mixin Foo!(y); // fails, matches multiple (???)
}

doesn't.  Why does Foo!(y) match Foo(int)?

A (kind of dumb) workaround is:

template Foo(b...)
{
    static assert(b.length == 1);
    int X = b[0];
}