gcc: Fixed Headers

1 
1 13.4 Fixed Header Files
1 =======================
1 
1 GCC needs to install corrected versions of some system header files.
1 This is because most target systems have some header files that won't
1 work with GCC unless they are changed.  Some have bugs, some are
1 incompatible with ISO C, and some depend on special features of other
1 compilers.
1 
1  Installing GCC automatically creates and installs the fixed header
1 files, by running a program called 'fixincludes'.  Normally, you don't
1 need to pay attention to this.  But there are cases where it doesn't do
1 the right thing automatically.
1 
1    * If you update the system's header files, such as by installing a
1      new system version, the fixed header files of GCC are not
1      automatically updated.  They can be updated using the 'mkheaders'
1      script installed in 'LIBEXECDIR/gcc/TARGET/VERSION/install-tools/'.
1 
1    * On some systems, header file directories contain machine-specific
1      symbolic links in certain places.  This makes it possible to share
1      most of the header files among hosts running the same version of
1      the system on different machine models.
1 
1      The programs that fix the header files do not understand this
1      special way of using symbolic links; therefore, the directory of
1      fixed header files is good only for the machine model used to build
1      it.
1 
1      It is possible to make separate sets of fixed header files for the
1      different machine models, and arrange a structure of symbolic links
1      so as to use the proper set, but you'll have to do this by hand.
1