http://d.puremagic.com/issues/show_bug.cgi?id=2929

           Summary: Alias this when this is null
           Product: D
           Version: 2.029
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: jason.james.house@gmail.com


The code below should demonstrate the problem.  The implicit use of alias this is not null-aware.  That means that a nullable class reference with alias this to another reference type is used, then segfaults will occur.  The only workaround is to define an intermediate variable and test for null before relying on the implicit alias to work.  This kind of kills the utility of alias this.

class A{}
class B{
  private A a;
  A foo(){ return a; }
  alias foo this;
}

void main(){
  B b;
  A a = b; // seg fault
  assert(a is null);
}


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=2929


Lukasz Wrzosek <luk.wrzosek@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |luk.wrzosek@gmail.com
         Resolution|                            |DUPLICATE


--- Comment #1 from Lukasz Wrzosek <luk.wrzosek@gmail.com> 2012-02-14 14:31:59 PST ---
*** This issue has been marked as a duplicate of issue 6777 ***

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Lukasz Wrzosek <luk.wrzosek@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|DUPLICATE                   |


--- Comment #2 from Lukasz Wrzosek <luk.wrzosek@gmail.com> 2012-02-14 14:34:36 PST ---
Sorry, it is not a duplicate ... :(

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
                 CC|                            |andrej.mitrovich@gmail.com
         Resolution|                            |INVALID


--- Comment #3 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-02-04 18:17:14 PST ---
I don't understand this report. alias won't protect you from null references, keeping references non-null is the programmer's responsibility.

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