Hi Eljay,
On Friday 04 March 2005 18:12, Eljay Love-Jensen wrote:
>>The question is why the #include_next directive in syslimits.h
>>results in including <gcc-include-dir>/limits.h, not in including
>>limits.h from the next directory in the search list.
>
> Because <gcc-include-dir>/limits.h is the first one in the search
> list.
>
> "This directive works like `#include' except in searching for the
> specified file: it starts searching the list of header file
> directories _after_ the directory in which the current file was
> found."
Well, I don't see here any clue that the current file shall have the
same name.
> <syslimits.h> is not <limits.h>
>
> The current <limits.h> file for the invocation within <syslimits.h>
> had not been found yet, so it starts with the first system include
> search path directory (i.e., <gcc-include-dir>).
Then try the following example:
- the <limits.h> header is copied from GCC include directory into
current directory
- the preprocessor is run with 'cpp -I.'
This results in:
#include "..." search starts here:
#include <...> search starts here:
.
/usr/local/include
/usr/lib/gcc-lib/i386-redhat-linux/3.3.3/include
/usr/include
Headers used:
. limits.h
#include "syslimits.h"
.. /usr/lib/gcc-lib/i386-redhat-linux/3.3.3/include/syslimits.h
#include_next <limits.h>
... /usr/include/limits.h
This way, you see, the #include_next directive results in including
from the directory _after_ the one <syslimits.h> resides in. If your
statement had been true, cpp would have included limits.h from
current directory again (since it is included from a header with a
different name).
Before you ask it: running 'cpp -isystem .' gives exactly the same
result.
Regards,
Alexey.
--
We are intelligent and clever, though you would never call us cunning.
-- Spathi, SC2
