Thanks for the answer, yes official mbed-rtos works.
But I wouldn't consider that a fix, but merely a workaround.
The purpose of the SparkFun fork was exactly to prevent that an experiment suddenly starts failing. The code was obviously working with some older version of armcc, so (given that it's correct C++) it should continue to work. If not, this is a bug in armcc which should be fixed.
Same with my own code. I don't want it to fail suddenly after a year or so without touching anything.
Additionally, the error is rather unspecific. There's no hint to the cause of the error at all. The build system is a bit of a black box.
But thanks anyway and sorry for the rant ;-)
I have trouble with compiling my program since today. It says; Error -230, The build system did not finish successfully.
Someone else having troubles with the online compiler?
note: a simple blinky program compiles fine...