http://d.puremagic.com/issues/show_bug.cgi?id=11169

           Summary: cannot create instance of abstract class
           Product: D
           Version: D2
          Platform: x86_64
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: pycerl@qq.com


--- Comment #0 from Zhouxuan <pycerl@qq.com> 2013-10-03 22:19:23 PDT ---
//////////////////////////////////////////////////////////// //case 1

class A
{
    abstract void foo();
}

class B : A
{
    static if( __traits(isAbstractClass, typeof(this) ))
    {
    }

    override void foo()
    {
    }
}

void main()
{
    B b = new B();
}

//Error: cannot create instance of abstract class B ////////////////////////////////////////////////////////////

//////////////////////////////////////////////////////////// //case 2

abstract class A
{
    void foo();
}

class B : A
{
    static if( __traits(isAbstractClass, typeof(this) ))
    {
    }

    override void foo()
    {
    }
}

void main()
{
    B b = new B();
}

//Okay ////////////////////////////////////////////////////////////

//////////////////////////////////////////////////////////// //case 3

class A
{
    abstract void foo();
}

class B : A
{
    override void foo()
    {
    }
}

void main()
{
    B b = new B();
}

//Okay ////////////////////////////////////////////////////////////

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Ali Cehreli <acehreli@yahoo.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |acehreli@yahoo.com


--- Comment #1 from Ali Cehreli <acehreli@yahoo.com> 2013-10-03 23:27:26 PDT ---
If others agree, please change the summary to something like

  __traits(isAbstractClass) uses the definition that it knows so far, not the
whole definition of the class


In any case, it would be a chicken and egg problem if static if tried to complete the definition of the class.

Ali

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--- Comment #2 from Zhouxuan <pycerl@qq.com> 2013-10-03 23:48:02 PDT ---
(In reply to comment #1)
> If others agree, please change the summary to something like
> 
>   __traits(isAbstractClass) uses the definition that it knows so far, not the
> whole definition of the class
> 
> 
> In any case, it would be a chicken and egg problem if static if tried to complete the definition of the class.
> 
> Ali

How about follow the rules of checking recursive alias?

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrej.mitrovich@gmail.com


--- Comment #3 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-10-04 04:32:31 PDT ---
(In reply to comment #1)
> If others agree, please change the summary to something like
> 
>   __traits(isAbstractClass) uses the definition that it knows so far, not the
> whole definition of the class

Internal note:

The issue is that __traits(isAbstractClass) has side-effects. It will call `ClassDeclaration::isAbstract`, but this will not only return the result but also set the internal `isabstract` field for the class (damn getter functions with side-effects..). I guess semantic() wasn't called on the class at that point.

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