Code:

	// test.d
	class A {}
	class B : A {}
	class C : A {}
	void main() {
		A[] objs = [ new B, new C ];	// line 6
	}

Compiler error:

	test.d(6): Error: cannot implicitly convert expression (new B) of type test.A to test.C
	test.d(6): Error: cannot implicitly convert expression ([(__error),new C]) of type C[] to A[]

I thought D was supposed to automatically infer the most derived common base class to assign to an array literal of different types? At least, that's the impression I got from TDPL.

What am I doing wrong?


T

-- 
MAS = Mana Ada Sistem?

On 03/06/2012 11:27 AM, H. S. Teoh wrote:
> Code:
>
> 	// test.d
> 	class A {}
> 	class B : A {}
> 	class C : A {}
> 	void main() {
> 		A[] objs = [ new B, new C ];	// line 6
> 	}
>
> Compiler error:
>
> 	test.d(6): Error: cannot implicitly convert expression (new B) of type test.A to test.C
> 	test.d(6): Error: cannot implicitly convert expression ([(__error),new C]) of type C[] to A[]
>
> I thought D was supposed to automatically infer the most derived common
> base class to assign to an array literal of different types? At least,
> that's the impression I got from TDPL.
>
> What am I doing wrong?
>
>
> T
>

That's probably this bug:

  http://d.puremagic.com/issues/show_bug.cgi?id=5498

Luckily it has a pull request.

Ali

On Tue, 06 Mar 2012 20:27:56 +0100, H. S. Teoh <hsteoh@quickfur.ath.cx> wrote:

> Code:
>
> 	// test.d
> 	class A {}
> 	class B : A {}
> 	class C : A {}
> 	void main() {
> 		A[] objs = [ new B, new C ];	// line 6
> 	}
>
> Compiler error:
>
> 	test.d(6): Error: cannot implicitly convert expression (new B) of type test.A to test.C
> 	test.d(6): Error: cannot implicitly convert expression ([(__error),new C]) of type C[] to A[]
>
> I thought D was supposed to automatically infer the most derived common
> base class to assign to an array literal of different types? At least,
> that's the impression I got from TDPL.
>
> What am I doing wrong?
>
>
> T
>

I have no idea (and haven't read TDPL), but adding a new A somewhere in the array makes it work. Compiler bug..?

You can use a cast as a workaround:
A[] objs = [cast(A)new B, new C ];

This bug has been around for a while, the first time I've seen it mentioned was in the second code snippet in this blog post: http://klickverbot.at/blog/2010/11/announcing-d-support-in-swig/