When compiling with /W2 and including <GL/glu.h>:
#include <windows.h>
#include <GL/gl.h>
#include <GL/glu.h>
void foo(void) {}
compiler produces a few warnings about missing prototypes:
...\PellesC\Include\Win\GL\glu.h(213): warning #2027: Missing prototype for '3', with type 'void __stdcall (*)()'.
...\PellesC\Include\Win\GL\glu.h(223): warning #2027: Missing prototype for '3', with type 'void __stdcall (*)()'.
...\PellesC\Include\Win\GL\glu.h(239): warning #2027: Missing prototype for '3', with type 'void __stdcall (*)()'.
I believe that void APIENTRY gluQuadricCallback(GLUquadric*,GLenum,void (CALLBACK*)()) should be void APIENTRY gluQuadricCallback(GLUquadric*,GLenum,void (CALLBACK*)(void)) etc.
Pelles C 7 and 8 RC2. Btw, Help->About in POIDE says that it is "Version 8.00.2 Release Candidate #1", but I'm 100% sure that I've installed RC2.