Arduino IDE preprocessor causes unknown type references from prototype creation

[JeffBobbo]

Functions using/returned an object, structs or using typedefs cause bad code to be fed to the compiler:

Source code:
http://0bin.net/paste/Xz5MZdbmuafYUQ2Q#567rrlhZy8-xCaiI7geiRXEZ+DFo92e4dpZ/cAJvJ3j

Arduino preprocessed code (fed to avr-g++):
http://0bin.net/paste/JgtLxMb23ZOaGJMu#RYZv9sCkcSXeapn0XXRCKphshFH38YLSHmGmn2Iy4EL

[matthijskooijman]

This is a bit of a known and hard-to-fix problem. I guess the most effective way to fix this would be to stop preprocessing sources. This is related to #992 an #386.

For now, you can fix this by manually specifying a protype, which should prevent the IDE from adding another one.

[ffissore]

We've just posted a new preprocessor version at https://groups.google.com/a/arduino.cc/d/msg/developers/4X2T3rCxXWM/WbQ2_dGzuhsJ
While it does not solve your issue, at least it allows you to work around it by specifying the prototype your self. Try adding a Foo makeFoo(); at line 21: the sketch will compile fine.

[ffissore]

Fixed by #3779