I am using MEC++ in VC 7.1.  I had a method on a __gc object that looked
like this:

__property System::UInt32 get_MyProperty(void)
   {
   System::Byte __pin * pinBytes = &m_byteArray[0];     // entire array is
now pinned
   NativeStruct const __nogc* nativeStructP = reinterpret_cast<NativeStruct
const __nogc*>(pinBytes);

   return nativeStructP->myField;
   }

Then I made another version of the property that didn't do any pinning.
Instead this version cast the address the first element of the managed byte
array member to a managed pointer to a native class like so:

__property System::UInt32 get_MyPropertyNoPin(void)
   {
   NativeStruct const __gc* nativeStructP= reinterpret_cast<NativeStruct
const __gc*>(&m_byteArray[0]);

   // what happens if the heap is compacted right here?  Am I guaranteed to
be OK when I dereference nativeStructP below since I'm using a __gc pointer?

   return nativeStructP->myField;
   }

It seems to compile and run just fine.  Can I really create tracking
references to native structs that, through pointer casting, really live in
the managed heap?  Will they track correctly if the heap is compacted?  Or
is this just a crash waiting to happen?

I actually didn't even expect this to compile.  I would have thought that
even declaring a __gc pointer to a __nogc type would result in a
compile-time error.  That it does compile and seems to run has me wondering
if it will actually work reliably.  If so, then it means that I can avoid
pinning much more than I thought that I could.

If this will work, will it still be possible to do this in C++/CLI in VC 8?

-Bern