(SOLVED) Calling pico-sdk methods within a sketch

I would like to call watchdog_reboot, which is defined in

ArduinoCore-mbed/cores/arduino/mbed/targets/TARGET_RASPBERRYPI/TARGET_RP2040/pico-sdk/rp2_common/hardware_watchdog/include/hardware/watchdog.h

The include statement I am using is
#include <hardware/watchdog.h>

The compiler can't find watchdog_reboot when I compile, but it does not give an error on the include statement.

More generally, how can I incorporate calls to the pico-sdk from a sketch?

Some of the sdk .h files aren't "protected" against being included by C++
Try this:

extern "C" {
#include <hardware/watchdog.h>
};

That did it. I totally forgot about the extern "C" sytanx.

Thanks much. This has saved me a large amount of work.