importing std.array: empty in a struct messes things up

[ag0aep6g]

On 03/04/2018 08:17 PM, Dennis wrote:
> I was making a stack interface for an array:
> ```
> struct Stack(T) {
>      import std.array: empty;
>      T[] stack;
>      alias stack this;
> }
> 
> void main()
> {
>      Stack!int stack;
>      bool x = stack.empty;
> }
> ```
> My expectation is that you can now call `empty` on a stack instance 
> since I imported it in the struct, but it gives this error:
> ```
> Error: cannot resolve type for stack.empty(T)(auto ref scope const(T) a) 
> if (is(typeof(a.length) : size_t) || isNarrowString!T)
> ```

`stack.empty` is an alias of `std.array.empty`. It's not a method of the 
struct. It's not a UFCS call to `std.array.empty`.

You can call it this way: `stack.empty(stack)`. You can also call it 
this way: `Stack!int.empty(stack)`. Maybe that makes it more obvious 
what's going on.

> When adding this method to the struct:
> ```
> bool empty() {return stack.empty;}
> ```
> 
> I get this confusing error:
> ```
> Error: expression stack.empty is void and has no value
> ```

I don't know what's going on here. The error message doesn't make sense 
to me. Might be a bug in the compiler.