I get this too. I'm using an MKS Gen L board with Reprap Discount Full Graphic Smart Controller, Arduino 1.8.9 and Marlin 1.1.9 with bugfix.
It doesn't seem to affect anything but it would be nice to get a completely clean compile.
I tried compiling with Arduino 1.8.5 and it doesn't show the error.
I would like to add that i am trying to compile the same exact marlin sketch and libs (synchronized directory on my network) on two different machines. Strangely enough, one lists the error described above and the other one does not (both arduino IDE v1.8.10).
Edited 1 time(s). Last edit at 11/04/2019 03:06PM by reaping miner.