>     #using <mscorlib.dll>
>     using namespace System;
>     static String *Zero() {return 0;}
>     void main() {
>         String *f[] = new String*[1];
>         if ((f[0] = Zero()) == 0)
>             Console::WriteLine(S"Zero() == 0");
>         else
>             Console::WriteLine(S"Zero() != 0");
>     }

> Even though Zero() returns 0, it will take the 'else' path.

> -Sean

> Ronald Laeremans
> Visual C++ compiler and libraries team

> > I'm having bad luck today.  It wasn't two minutes after I worked around
> the
> > value/enum compiler bugs that I stumbled into another one:

> >     #using <mscorlib.dll>
> >     using namespace System;
> >     static String *Zero() {return 0;}
> >     void main() {
> >         String *f[] = new String*[1];
> >         if ((f[0] = Zero()) == 0)
> >             Console::WriteLine(S"Zero() == 0");
> >         else
> >             Console::WriteLine(S"Zero() != 0");
> >     }

> > Even though Zero() returns 0, it will take the 'else' path.

> > -Sean

> //000018:   if ((f[0] = Zero()) == 0)
>   IL_0009:  ldloc.0
>   IL_000a:  ldc.i4.0
>   IL_000b:  call       string
> modopt([mscorlib]System.Runtime.CompilerServices.CallConvCdecl)
> ?A0x3d035f1e.Zero()
>   IL_0010:  stelem.ref
>   IL_0011:  ldloc.0
>   IL_0012:  ldc.i4.0
>   IL_0013:  ldelem.u4  // I changed this manually to ldelem.ref, then it
> works
>   IL_0014:  brtrue.s   IL_0022

> whereas
> if ((f[0]) == 0)
> compiles to this

> //000018:   if ((f[0]) == 0)
>   IL_0009:  ldloc.0
>   IL_000a:  ldc.i4.0
>   IL_000b:  ldelem.ref
>   IL_000c:  brtrue.s   IL_001a

> > == on Object* or on any other reference type will compare pointer
values.
> > Non const inited strings aren't interned so the pointer values will be
> > different. You will need to call compare on the strings.

> > Ronald Laeremans
> > Visual C++ compiler and libraries team

> > > I'm having bad luck today.  It wasn't two minutes after I worked
around
> > the
> > > value/enum compiler bugs that I stumbled into another one:

> > >     #using <mscorlib.dll>
> > >     using namespace System;
> > >     static String *Zero() {return 0;}
> > >     void main() {
> > >         String *f[] = new String*[1];
> > >         if ((f[0] = Zero()) == 0)
> > >             Console::WriteLine(S"Zero() == 0");
> > >         else
> > >             Console::WriteLine(S"Zero() != 0");
> > >     }

> > > Even though Zero() returns 0, it will take the 'else' path.

> > > -Sean

> That's exactly what I intended to do:  compare pointer values.

> I guess String* was a bad choice for my example since it has overloaded
> operators, but the same problem occurs no matter what the object type is.

> This bug is triggered with the combination of returning a managed pointer
> from a function, assigning it into an array and checking that result for
> null.

> I don't believe my original code was too far-fetched:  I wrote a loop to
> fill an array with objects from a factory method.  Within that loop I
would
> throw an exception if the factory method returned null.  However, this bug
> prevents the exception from ever being thrown; even if a null was assigned
> into the array.  This caused null reference exceptions later on in the
code.

> -Sean