What are the rules regarding one interface (not class, but interface) inheriting from another?

Nothing in the documentation seems to refer to interface inheritance, only to class inheritance.

I have tried to do some code with this, and the compiler does not complain about one interface inhering from another, but it does give some strange results when the child interface tries to implement an abstract method in the parent interface.

What I am trying to do in structurally like this:

interface I1
{
    abstract x *A();
}

interface I2: I1
{
    final x *A() { ... }
    final int B() { return f(A()); }
}

interface I3: I1
{
    final int C() { return g(A()); }
}

class C1: I3
{
    final x *A() { ... }
}

class C2: I2
{
   // should not need to define A() because that should be defined in I2
   // Not allowed to define A() because already defined in I2
}

On Tuesday, 5 September 2017 at 20:15:44 UTC, GGB wrote:
> What are the rules regarding one interface (not class, but interface) inheriting from another?
>
> Nothing in the documentation seems to refer to interface inheritance, only to class inheritance.
>
> I have tried to do some code with this, and the compiler does not complain about one interface inhering from another, but it does give some strange results when the child interface tries to implement an abstract method in the parent interface.
>

This is related to Issue 2538:
https://issues.dlang.org/show_bug.cgi?id=2538

The spec has more information on interfaces here
https://dlang.org/spec/interface.html

On Tuesday, 5 September 2017 at 21:44:07 UTC, jmh530 wrote:
>
> This is related to Issue 2538:
> https://issues.dlang.org/show_bug.cgi?id=2538
>
> The spec has more information on interfaces here
> https://dlang.org/spec/interface.html

And here is a simpler example:

interface I1
{
    void A();
}

interface I2: I1
{
    final void A() { }
}

class B: I2
{
   //It is an error to declare this class either with A or without it
}

On Tuesday, 5 September 2017 at 21:45:51 UTC, jmh530 wrote:
> On Tuesday, 5 September 2017 at 21:44:07 UTC, jmh530 wrote:
>>
>> This is related to Issue 2538:
>> https://issues.dlang.org/show_bug.cgi?id=2538
>>
>> The spec has more information on interfaces here
>> https://dlang.org/spec/interface.html
>
> And here is a simpler example:
>
> interface I1
> {
>     void A();
> }
>
> interface I2: I1
> {
>     final void A() { }
> }
>
> class B: I2
> {
>    //It is an error to declare this class either with A or without it
> }

Thanks, I think that explains it, although neither the documentation nor the compiler messages make things clear.