LCD configuration error

Hello, So as of today I've gone back into modifying the Marlin code for my Folger tech Prusa i3 as i've recently acquired an LCD display with an SD card slot. Now because my old laptop help all the source code, and that old laptop was a mac worthy of jurassic world, it crapped out pretty soon and dragged all my source code down with it. Everything else is finally up to where it was before however when removing the forward slashes in front of "#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER" to enable the LCD and compile the program i get the error

Variable or field 'getpos' declared void

SdBaseFile.cpp:297: error: variable or field 'getpos' declared void
SdBaseFile.cpp:297: error: 'fpos_t' was not declared in this scope
SdBaseFile.cpp: In member function 'int SdBaseFile::peek()':
SdBaseFile.cpp:928: error: 'pos' was not declared in this scope
SdBaseFile.cpp: At global scope:
SdBaseFile.cpp:1495: error: variable or field 'setpos' declared void
SdBaseFile.cpp:1495: error: 'fpos_t' was not declared in this scope

ive attempted renaming "fpos_t" to something else like "fpos_t1" at no avail of course...

if you have anything you think may help please do share. Thanks!