Code works in Arduino IDE but will not complie in PlatformIO

[MnemonicFish]

Code works great in Arduino but cant figure out the issue in PlatformIO

`/*
 This is a sample sketch to show how to use the OneButtonLibrary
 to detect double-click events on a button. 
 The library internals are explained at
 http://www.mathertel.de/Arduino/OneButtonLibrary.aspx
  
 Setup a test circuit:
 * Connect a pushbutton to pin A1 (ButtonPin) and ground.
 * The pin 13 (StatusPin) is used for output attach a led and resistor to ground
   or see the built-in led on the standard arduino board.
   
 The sketch shows how to setup the library and bind the functions (singleClick, doubleClick) to the events.
 In the loop function the button.tick function must be called as often as you like.
*/

// 03.03.2011 created by Matthias Hertel
// 01.12.2011 extension changed to work with the Arduino 1.0 environment

#include "OneButton.h"

#if defined(ARDUINO_AVR_UNO) || defined(ARDUINO_AVR_NANO_EVERY)
// Example for Arduino UNO with input button on pin 2 and builtin LED on pin 13
#define PIN_INPUT 2
#define PIN_LED 13

#elif defined(ESP8266)
// Example for NodeMCU with input button using FLASH button on D3 and using the led on -12 module (D4).
// This LED is lighting on output level LOW.
#define PIN_INPUT D3
#define PIN_LED D4

#elif defined(ESP32)
// Example pin assignments for a ESP32 board
// Some boards have a BOOT switch using GPIO 0.
#define PIN_INPUT 0
// Attach a LED using GPIO 25 and VCC. The LED is on when output level is LOW.
#define PIN_LED 25

#endif

// Setup a new OneButton on pin PIN_INPUT
// The 2. parameter activeLOW is true, because external wiring sets the button to LOW when pressed.
  OneButton button(PIN_INPUT, true);

// In case the momentary button puts the input to HIGH when pressed:
// The 2. parameter activeLOW is false when the external wiring sets the button to HIGH when pressed.
// The 3. parameter can be used to disable the PullUp .
// OneButton button(PIN_INPUT, false, false);

// current LED state, staring with LOW (0)
int ledState = LOW;

// setup code here, to run once:
void setup()
{
  Serial.begin(115200);
  Serial.println("One Button Example with polling.");

  button.setDebounceTicks(2);

  // enable the standard led on pin 13.
  pinMode(PIN_LED, OUTPUT); // sets the digital pin as output

  // enable the standard led on pin 13.
  digitalWrite(PIN_LED, ledState);

  // link the doubleclick function to be called on a doubleclick event.

  button.attachClick(Click);
} // setup


// main code here, to run repeatedly:
void loop()
{
  // keep watching the push button:
  button.tick();

  // You can implement other code in here or just wait a while
  delay(10);
} // loop


// this function will be called when the button was pressed 2 times in a short timeframe.
void Click()
{
  Serial.println("x2");

  ledState = !ledState; // reverse the LED
  digitalWrite(PIN_LED, ledState);
} // doubleClick

// End

`

[mathertel]

You are compiling main.cpp not an Arduino Sketch file.
Please declare/define/implement BEFORE referencing.
( Move the Click() function before setup()).

[MnemonicFish]

Fantastic, that did the trick.. thanks mathertel!

/*
 This is a sample sketch to show how to use the OneButtonLibrary
 to detect double-click events on a button. 
 The library internals are explained at
 http://www.mathertel.de/Arduino/OneButtonLibrary.aspx
  
 Setup a test circuit:
 * Connect a pushbutton to pin A1 (ButtonPin) and ground.
 * The pin 13 (StatusPin) is used for output attach a led and resistor to ground
   or see the built-in led on the standard arduino board.
   
 The sketch shows how to setup the library and bind the functions (singleClick, doubleClick) to the events.
 In the loop function the button.tick function must be called as often as you like.
*/

// 03.03.2011 created by Matthias Hertel
// 01.12.2011 extension changed to work with the Arduino 1.0 environment

#include "OneButton.h"

#define PIN_INPUT 4
// Attach a LED using GPIO 25 and VCC. The LED is on when output level is LOW.
#define PIN_LED 17

// Setup a new OneButton on pin PIN_INPUT
// The 2. parameter activeLOW is true, because external wiring sets the button to LOW when pressed.
  OneButton button1(4, true);

// In case the momentary button puts the input to HIGH when pressed:
// The 2. parameter activeLOW is false when the external wiring sets the button to HIGH when pressed.
// The 3. parameter can be used to disable the PullUp .
// OneButton button(PIN_INPUT, false, false);

// current LED state, staring with LOW (0)
int ledState = LOW;

// this function will be called when the button was pressed 2 times in a short timeframe.
void Click1()
{
  Serial.println("x2");

  ledState = !ledState; // reverse the LED
  digitalWrite(PIN_LED, ledState);
} // doubleClick

// End

// setup code here, to run once:
void setup()
{
  Serial.begin(115200);
  Serial.println("One Button Example with polling.");

  // enable the standard led on pin 13.
  pinMode(PIN_LED, OUTPUT); // sets the digital pin as output

  // enable the standard led on pin 13.
  digitalWrite(PIN_LED, ledState);

  // link the doubleclick function to be called on a doubleclick event

  button1.attachClick(Click1);
  //button1.attachDoubleClick(doubleclick1);
  //button1.attachLongPressStart(longPressStart1);
  //button1.attachLongPressStop(longPressStop1);
  //button1.attachDuringLongPress(longPress1);

} // setup

// main code here, to run repeatedly:
void loop()
{
  // keep watching the push button:
  button1.tick();

  // You can implement other code in here or just wait a while
  delay(10);
} // loop