There have been rumblings and rumors for a while now about a native Mac OS X port of AutoCAD. The ObjectARX 2011 SDK header files contain clear evidence of a native Mac port in the works. The evidence comes in the form of code comments and changes made to the files so that they work with the GCC compiler and the Mac OS X libraries.
For example, acedads.h conditionally declares a global function to return the main window handle as follows:
#if defined(_WINDEF_) || defined(_ADESK_MAC_)
/* AutoCAD graphics window handle */
#define adsw_hwndAcad adsw_acadMainWnd()
And in acedinpt.h there’s a telling comment:
#define ACAD_PORT _declspec(dllexport)
// On OS X, we will export all symbols by default and will use GCC
// attributes to exclude symbols we don’t want to export.
// In this case, we do want to export the AcEdInputPoint symbol
#endif // _ADESK_MAC_
It’s clear from the type, quantity, and quality of changes that Autodesk has successfully built at least a limited AutoCAD executable for OS X (both 32 and 64 bit). It’s also clear that the Mac build still has limitations, and some of these limitations might require significant changes (i.e. changes of the sort that would break binary compatibility for ObjectARX applications), therefore one could reasonably conclude that no full-blown Mac port is imminent.