win64 - win32.oaidl.VARIANT -> error LNK2019

[deed via Digitalmars-d-learn]

// bindings from 
https://github.com/CS-svnmirror/dsource-bindings-win32/blob/308739a417eaaba85a5d3ce7741fd43d3042efe0/oaidl.d

---
import win32.oaidl;

// The following gives linker error: error LNK2019: unresolved 
external
// symbol _D5win325oaidl7VARIANT6__initZ referenced
// in function ...
VARIANT v;
v.vt = VARENUM.VT_I4;
v.lVal = 1;

// while this works - no linker error
VARIANT v = { vt: VARENUM.VT_I4, lVal: 1 };


Defining a similar structure as VARIANT with anonymous structs 
and unions targeting linux seemed to work fine without linker 
problems. What is the idiomatic way of handling this on win64?