Bindgen generates wrong bingings for function

[TheRadioGuy]

Input C/C++ Header

    typedef
        _Function_class_(EVT_VIGEM_X360_NOTIFICATION)
        VOID CALLBACK
        EVT_VIGEM_X360_NOTIFICATION(
            PVIGEM_CLIENT Client,
            PVIGEM_TARGET Target,
            UCHAR LargeMotor,
            UCHAR SmallMotor,
            UCHAR LedNumber,
            LPVOID UserData
        );

    typedef EVT_VIGEM_X360_NOTIFICATION *PFN_VIGEM_X360_NOTIFICATION;

Bindgen Invocation

$ bindgen .\ViGEmClient.cpp -o mod.rs  --whitelist-function 'vigem_.*' 

Actual Results

pub type PFN_VIGEM_X360_NOTIFICATION = ::std::option::Option<unsafe extern "C" fn()>;

Expected Results

In rust bindings, there's function with no params, but as we can see in CPP code - there's a lot of params.

By the way, bindings
headers

[TheRadioGuy]

And there's no EVT_VIGEM_X360_NOTIFICATION in bindings :(

[emilio]

This seems similar to some other issues where libclang doesn't expose the arguments probably, then bindgen tries to guess from the AST, but it still fails because of macros.

Can you paste a definition of EVT_VIGEM_X360_NOTIFICATION and the other macros in use here? Ideally a chunk of code that reproduces the issue entirely is the most helpful.

Thanks for filing!

[emilio]

Ah, apparently _Function_class_ is some sort of VC++ annotation. TIL

[emilio]

You need to find where CALLBACK and VOID are defined and so on.

[TheRadioGuy]

There's void.
and I could not find CALLBACK definition

[emilio]

No, I know what void is, this is about VOID (uppercase). The definition is probably in one of the windows headers.

It seems CALLBACK is just __stdcall.

[emilio]

So something like this should do:

#define VOID void
#define CALLBACK __stdcall
#define UCHAR unsigned char

typedef
    VOID CALLBACK
    EVT_VIGEM_X360_NOTIFICATION(
        void* Client,
        void* Target,
        UCHAR LargeMotor,
        UCHAR SmallMotor,
        UCHAR LedNumber,
        void* UserData
    );

typedef EVT_VIGEM_X360_NOTIFICATION *PFN_VIGEM_X360_NOTIFICATION;

[emilio]

This is a libclang bug, https://bugs.llvm.org/show_bug.cgi?id=45919.

But we can workaround it in bindgen to some extent.

[TheRadioGuy]

I have not checked it yet, but thank you!