Using VSCode:

Take care that C/C++ intellisense and C/C++ Clang Command Adapter are not installed as this plugin already includes them.

Autoformat cpp files

In vscode settings change the parameter C_Cpp: Clang_format_style and set as value: {BasedOnStyle: 'Chromium'}

This will format the code like:

void test() {}

void test2() {
  int a = 1;
  for (int b = 0; b < 10; b++) {
    a += b;
  }
}

Program bootloader with PlatformIO and USBTinyISP

Go to the platformIO terminal and type:

$ pio run -e program_via_USBtinyISP --target bootloader