I am making a multi-file arduino project, but the compiler can't recognize a function. I am using the arduino-cli version 0.10.0

This is the error I received

undefined reference to pin_init() collect2.exe: error: ld returned 1 exit status Error during build: exit status 1

This is the command:

arduino-cli compile -b arduino:avr:uno C:\Users\Cioccarelli\Desktop\transmitterCopy\main

main.ino:

#include "C:\Users\Cioccarelli\Desktop\transmitter\automation\automation.h"

void setup() {
    pin_init();
}

void loop() {}

automation.h:

#pragma once

// This is where the components input pins are stored, they are put here by the add_pin function
byte pinSetup[0];
byte pinSetupSize = 0;

// This function is called in the setup() and it initializes every pin listed in pinSetup[] as input
void pin_init();

automation.cpp:

#include "C:\Users\Cioccarelli\Desktop\transmitter\automation\automation.h"

extern pinSetup;
extern pinSetupSize;

void pin_init() {
    for (int i = 0; i < pinSetupSize; i++)
        pinMode(i, INPUT);
}

I think this issue might have to do with the fact that I don't completely understand file inclusion, but I haven't found anything useful in my research