Language support for [FixedAddressValueType]

[DaZombieKiller]

FixedAddressValueType allows you to declare a static field as fixed. However, the language doesn't currently treat these fields as fixed, and thus you cannot use the address-of operator on them, instead needing to use a fixed block or Unsafe.AsPointer:

[FixedAddressValueType]
static int someStaticValue;

// ...

fixed (int* p = &someStaticValue)
    SomeUnsafeMethod(p);
    
// alternatively
SomeUnsafeMethod((int*)Unsafe.AsPointer(ref someStaticValue));

This can make it annoying when working with function pointers, as you will need to duplicate the function pointer signature (since you can only use a fixed statement in this situation):

[FixedAddressValueType]
public unsafe static delegate* unmanaged<void> Original;

public unsafe static readonly delegate* unmanaged<void> Detour = &DetourMethod;

// ...

Detours.TransactionBegin();
Detours.UpdateThread(thread);

fixed (delegate* unmanaged<void>* f = &Original)
    Detours.Attach((void**)f, Detour);

Detours.TransactionCommit();