Hi (re posting as my last post seemed to vanish?)
Using the online editor I am having issues verifying any program for the UNO board.
I have tried using "blink" unchanged from the example library, it works fine with the "Arduino/Genuino 101" board selected, but when I select the UNO from the board menu i get the following error:
Linking everything together... lto1: fatal error: bytecode stream in file '/tmp/014847833/build/../../core/core_arduino_avr_uno_0fd389f0184d5a21fcc443ff311da7f1.a' generated with LTO version 4.1 instead of the expected 6.0 compilation terminated. lto-wrapper: fatal error: /home/builder/.arduino15/packages/arduino/tools/avr-gcc/7.3.0-atmel3.6.1-arduino5/bin/avr-gcc returned 1 exit status compilation terminated. /home/builder/.arduino15/packages/arduino/tools/avr-gcc/7.3.0-atmel3.6.1-arduino5/bin/../lib/gcc/avr/7.3.0/../../../../avr/bin/ld: error: lto-wrapper failed collect2: error: ld returned 1 exit status exit status 1