Zhiyi Zhang (@zhiyi) commented about dlls/wintypes/propertyset.c:
static HRESULT STDMETHODCALLTYPE propertyset_QueryInterface( IPropertySet *iface, REFIID iid, void **out ) {
struct propertyset *impl;
TRACE( "(%p, %s, %p)\n", iface, debugstr_guid( iid ), out );
impl = impl_from_IPropertySet( iface );
Let's initialize it when doing the variable declaration.