Bug in mixins?

[John Colvin]

On Friday, 7 March 2014 at 06:23:58 UTC, Frustrated wrote:
> Can someone check this out? The best I can acertain is that the 
> mixin template isn't adding the generated functions because it 
> thinks they are already in the class.
>
> i.e., the code generates the following methods
>
> @property iButton button(iButton b)
> @property iBorder border(iBorder b)
>
> and the class contains the methods
>
> @property WindowsButton button()
> @property WindowsButton button(WindowsButton b)
>
> and the template mixin simply doesn't add the generic methods. 
> (simply because mixing the string mixin directly works, 
> wrapping it in a mixin template does not)
>
> Using that I created a MWE:
>
> http://dpaste.dzfl.pl/6f64e49aba95
>
>
>
> import std.stdio, std.cstream;
>
> // mixin template used to wrap the string mixin
> mixin template C() { mixin(B); }
>
> // eponymously named template used as a string mixin to 
> generate the function
> template B()
> {
> 	string B() { return "void foo(iA a) { writeln(`Generic`);  }"; 
> }
> }
>
> interface iA {	void foo(iA a); }
>
> class A : iA
> {
> 	void foo(A a) { writeln("Specific"); }
> 	//mixin(B);
> 	mixin C;    // doesn't work, use line above, does not insert 
> generic foo
> }
>
>
> void main()
> {
> 	iA a = new A;
> 	a.foo(a);
> 	(cast(A)a).foo(cast(A)a);
> 	(cast(A)a).foo(a);  // line doesn't work when using mixin 
> template because the generic foo does not exist
> }
>
>
> This seems like a bug to me but maybe that's how mixin 
> templates work? If so is there any way to make them insert the 
> code regardless if it thinks they are the same? (they are not 
> in this case and I need to use them to reduce redundancy)

functions introduced through mixin templates do not take part in 
overload resolution when an overload exists outside the mixin.
It's a common annoyance, I can't remember if there's a good 
reason for it.