I got this error while (re)building, using cygwin make.exe version :3.81.
Error : *** target pattern contains no `%\'.
Try this if you're running Eclipse C/C++ and referencing files from Cygwin under Windows, make sure c:/cygwin/bin or c:/cygwin64/bin comes after your preferred compiler tools in your Windows Path environment.
Example: Path = ;C:\yagarto\bin;C:\yagarto-tools\bin;C:\cygwin64\bin;
After making the changes, exit Eclipse and restart for it to take effect (simply restarting Eclipse without exiting won't fix the problem.