hidapi: fix function pointer type mismatch in backend table

[ArnauNau]

Summary

Fixes a Clang UBSan function sanitizer TRAP in the HIDAPI backend table.

The HIDAPI backend table used generic void * function pointers, but the PLATFORM, DRIVER, and LIBUSB backends are compiled into this translation unit with macro-renamed device types. Calling those backend functions directly through the generic table leaves an incompatible indirect function call.

To fix this, I added small backend wrappers so the backend table calls functions with the expected type, and the cast to the backend-specific device type happens inside a direct call.

I first tested the approach by using a direct wrapper approach like this:

#ifdef HAVE_PLATFORM_BACKEND
static int PLATFORM_hid_set_nonblocking_backend(hid_device *device, int nonblock)
{
    return PLATFORM_hid_set_nonblocking((PLATFORM_hid_device *)device, nonblock);
}


static const struct hidapi_backend PLATFORM_Backend = {
    PLATFORM_hid_write_backend,
    PLATFORM_hid_read_timeout_backend,
    ...
};
#endif

but after writing the PLATFORM ones and seeing DRIVER and LIBUSB would need their too, I went the macro direction. To me it looks simpler / cleaner; but I can go back to the other way if requested.

Testing

Built SDL with (LLVM) Clang 22.1.7 using:

-fsanitize=undefined,function -fsanitize-trap=undefined,function -fno-sanitize-recover=all

Verified:

• SDL_Init(SDL_INIT_GAMEPAD) no longer traps with a PS5 DualSense connected.
• SDL_GetGamepads reports the connected controller.

[slouken]

Interesting. I'm not even sure how clang can detect this at runtime, but your change looks fine to me.

Thanks!

[slime73]

Missing the code authorship confirmation?

[ArnauNau]

• I confirm that I am the author of this code and release it to the SDL project under the Zlib license. This contribution does not contain code from other sources, including code generated by a Large Language Model ("AI").

@slime73 sorry about that, I didn't see any contribution guidelines and last time I made a PR I don't remember needing to do that.