Detect unused header files?

[Sam Ravnborg <sam@ravnborg.org>]

In the kernel we would like to avoid all
unused include files.
Especially in the headers we export to userspace.

Are there any easy way we can use sparse to detect
that a specific header file is not used?

I know this will depend on the configuration, but
for the use I have in mind this does matter only a little.

The header files I have in mind will be fully self-contained
as they all include the header files they need to be used.

Sample:

cat foo.h:
#include <linux/types.h>
#include <linux/swab.h>

struct foo {
        __u32 bar;
        __u32 baz;
};

EOF


Here <linux/swab.h> is obviously not used.
And I would like sparse to flag this...

	Sam