What version of Go are you using (go version)?

$ go version
go version go1.20 windows/amd64

Does this issue reproduce with the latest release?

Yes.

What operating system and processor architecture are you using (go env)?

$ go env
    :
GOARCH=amd64
GOOS=windows
    :

What did you do?

Some of the Windows system dynamic link library (DLL) files have extensions other than .dll.
For example,

• ActiveX Controls files with .ocx extension
• Control Panel applets with .cpl extension
• Device drivers with .drv extension

mkwinsyscall does not support generating the syscall wrappers for these DLLs with different extensions.
The extension is always hard-coded to .dll in the generated code.

//sys ClosePrinter(h syscall.Handle) (err error) = winspool.ClosePrinter

What did you expect to see?

var (
        modwinspool = windows.NewLazySystemDLL("winspool.drv")
        procClosePrinter = modwinspool.NewProc("ClosePrinter")
)

What did you see instead?

var (
        modwinspool = windows.NewLazySystemDLL("winspool.dll")
        procClosePrinter = modwinspool.NewProc("ClosePrinter")
)

Proposed solution

If the user specified the extension of the DLL in the //sys comment, use that extension instead of adding the .dll extension.
Going back to the previous example, the user can specify the extension as .drv in the //sys comment.

//sys ClosePrinter(h syscall.Handle) (err error) = winspool.drv.ClosePrinter

Then, the generated code will be,

var (
        modwinspool = windows.NewLazySystemDLL("winspool.drv")
        procClosePrinter = modwinspool.NewProc("ClosePrinter")
)

The code changes are fairly straightforward. I have working code that I can submit as a pull request if the proposal makes sense.