On 30 April 2011 12:39, ali hagigat wrote: > 3.14 Options for Directory Search > -Idir > This is to ensure that GCC’s procedure to fix buggy system > headers and the ordering for the include next directive are not > inadvertently hanged. > ----------------------------- > Sorry I do not have the answer yet!! I understood "include_next" > directive but what is the procedure of GCC to fix the system headers? GCC installs fixed versions of buggy system headers, as part of the gcc installation tree. Those headers are used instead of the original system ones. > When we specify a path with -I and it is ignored because there is the > same name in the system directories, how it can fix the system headers > then? Because the system directories (including the one containing the fixed headers) are still searched as normal. It really isn't complicated: if a directory is considered as a system directory and it is also named with -I, then the -I option is ignored. BUT THE DIRECTORY IS STILL SEARCHED AS A SYSTEM DIRECTORY. Like Ian said, if you say: -isystem foo -I foo then the -I option is ignored and it is equivalent to: -isystem foo This ensures that if 'foo' contains buggy system headers then those headers will not be found before the fixed versions, because gcc searches the directory containing the fixed headers before it searches other system directories.
