Consider the following code:

/*********** mmio.d ************/
module mmio;

mixin template HasValue(uint value) {
    static uint getValue() {
        return value;
    }
}

mixin template Parent() {
    final abstract class Child(uint value) {
        mixin HasValue!(value);
    }
}

/*********** test.d ************/
module test;
import mmio;

mixin Parent;

alias Two = Child!(2);

/*********** main.d ************/
import std.stdio;
import test;

void main()
{
    writeln(__traits(parent, test.Two).stringof);
    writeln(__traits(parent, __traits(parent, test.Two)).stringof);

    readln();
}

DMD 2.065 Output:
Child!(2)
Child!(2)

GDC 4.8.2 20130725 Output:
Child
Child

LDC 0.12.1 Output:
Child
Chlld

All of these seem wrong to me.  What I expect for output is:
module test
{the second `writeln` shouldn't compile since `test` has no parent}

A couple of observations:
1. `Child` is not the parent of `test.Two`, `test` is the parent of `test.Two`.
2. If you believe `__traits(parent, test.Two)` is `Child`, `Child` should not be its own parent.

Incidentally, if I remove the template parameter on `Child`, I get the results I expect.

Could someone please confirm if this is a bug or not?

Thanks for the help,
Mike

On Saturday, 29 March 2014 at 03:00:30 UTC, Mike wrote:
> Consider the following code:
>
> /*********** mmio.d ************/
> module mmio;
>
> mixin template HasValue(uint value) {
>     static uint getValue() {
>         return value;
>     }
> }
>
> mixin template Parent() {
>     final abstract class Child(uint value) {
>         mixin HasValue!(value);
>     }
> }
>
> /*********** test.d ************/
> module test;
> import mmio;
>
> mixin Parent;
>
> alias Two = Child!(2);
>
> /*********** main.d ************/
> import std.stdio;
> import test;
>
> void main()
> {
>     writeln(__traits(parent, test.Two).stringof);
>     writeln(__traits(parent, __traits(parent, test.Two)).stringof);
>
>     readln();
> }
>
> DMD 2.065 Output:
> Child!(2)
> Child!(2)
>
> GDC 4.8.2 20130725 Output:
> Child
> Child
>
> LDC 0.12.1 Output:
> Child
> Chlld
>
> All of these seem wrong to me.  What I expect for output is:
> module test
> {the second `writeln` shouldn't compile since `test` has no parent}
>
> A couple of observations:
> 1. `Child` is not the parent of `test.Two`, `test` is the parent of `test.Two`.
> 2. If you believe `__traits(parent, test.Two)` is `Child`, `Child` should not be its own parent.
>
> Incidentally, if I remove the template parameter on `Child`, I get the results I expect.
>
> Could someone please confirm if this is a bug or not?
>
> Thanks for the help,
> Mike

https://d.puremagic.com/issues/show_bug.cgi?id=12496