adafruit/Adafruit-GFX-Library — pull request #37 by Chobbes (2014-11-10 09:44:19+00:00)
Title: Made swap a function to prevent awful error messages from macros.

This macro causes a lot of grief for poor students who aren't yet familiar with gcc's dreadful error messages. Unfortunately "swap" is a common name for functions, and if people aren't careful and declare their own functions when including Adafruit_GFX.h you get a misleading error, as opposed to a duplicate declaration one.