Platformio fail to printf() floats

main.cpp

// AlertAvert.com (c) 2016. All rights reserved
//
// The code below has been adapted from tutorials on
// mbed.org - credits should go to ARM Ltd.
//
// Author: M. Massenzio

#include "mbed.h"

// USB out to the host PC - from a terminal window access
// using: screen /dev/ttyACM0 (use Ctrl-A Ctrl-K to kill).
//
// On OS X, to find the dev do:
//   ls /dev/tty.usbmodem*
//
Serial pc(USBTX, USBRX); // tx, rx

// Board LEDs
DigitalOut myled(LED1);
DigitalOut yourled(LED2);

bool on = true;
void quit() {
  on = false;
}

void toggle(DigitalOut d1, DigitalOut d2) {
  d1 = !d1;
  d2 = !d2;
}

int main() {
  float intvl = 0.2f;
  
  pc.printf("Starting LED flashing every %.3f sec\r\n", intvl);
  Timeout to;
  myled = !(yourled = 1);
  to.attach(&quit, 5);
  while(on) {
    toggle(myled, yourled);
    wait(0.2);
  }
  myled = yourled = 0;
  pc.printf("Exiting now - %.3f; %d; %f\r\n", 3.14159, 99, 2.768);
}