I am using Qt-Creator on Mac OS X for C++-development (I don't use Qt itself). The strange thing is, that Qt-Creator is unable to find any files that are directly in /usr/inlcude. Everything still compiles, but I just cannot use features like autocomplete or "Follow symbol under cursor" in Qt-Creator because of that.
So for C++ headers like iostream, everything works as expected, it finds the header files and indexes them correctly. But if I want to use something from unistd.h, Qt-Creator does not find the include directory. I am using clang 5.2 (from Apple) and Mac OS X 10.9.2.
I even tried adding this (redundant) line to my CMakeLists.txt file:
include_directories(/usr/include)
but that does not help. It is nothing I can not live with, but it is still frustrating.