What is the Most Effective Tool to Convert WinAPI Headers?

[DanielG]

Ideally somebody would create a WinRT "projection" for Dlang. As 
I understand it there are some metadata (winmd) files that 
describe the full COM API surface, so idiomatic binding 
generation can be automated.

I've not gone any deeper but on the surface it sounds roughly 
similar to how GTK bindings are produced from GIR metadata.