Re: [RFC] duplicate #include check for build system

[Randy.Dunlap]

On Wed, 22 Feb 2006, Herbert Poetzl wrote:

> On Tue, Feb 21, 2006 at 04:18:57PM -0800, Randy.Dunlap wrote:
> > On Wed, 22 Feb 2006, Herbert Poetzl wrote:
> >
> > > On Tue, Feb 21, 2006 at 06:52:46PM +0100, Sam Ravnborg wrote:
> > > > On Tue, Feb 21, 2006 at 02:29:12AM -0500, Daniel Barkalow wrote:
> > > > > On Tue, 21 Feb 2006, Herbert Poetzl wrote:
> > > >
> > > > > I think the kernel style is to encourage duplicate includes,
> > > > > rather than removing them. Removing duplicate includes won't
> > > > > remove any dependancies (since the includes that they duplicate
> > > > > will remain).
> > >
> > > > The style as I have understood it is that each .h file in
> > > > include/linux/ are supposed to be self-contained. So it includes
> > > > what is needs, and the 'what it needs' are kept small.
> > > >
> > > > Keeping the 'what it needs' part small is a challenge resulting
> > > > in smaller .h files. But also a good way to keep related things
> > > > together.
> > >
> > > glad that I stimulated a philosophical discussion
> > > about the kernel header files and what they should
> > > include or not ...
> > >
> > > but the idea was more to give the developers an
> > > instrument to verify that they are not including
> > > stuff several times, and that's actually in .h
> > > and .c files, because it seems that often the same
> > > header file is included twice in the _same_ file
> > >
> > > anyway, was this a positive or negative reply?
> >
> > Hi Herbert,
> >
> > The goal is not to remove the most possible #includes.
>
> which I totally agree with ...
>
> but a) how is that related to _having_ a tool to
> check for duplicate includes, and b) how is it
> related to removing duplicate includes in general?
>
> let me give a simple example here:
>
>  #include <linux/pm.h>
>  #include <linux/sched.h>
>  #include <linux/proc_fs.h>
> -#include <linux/pm.h>
>
> do you think the second one is really desired?

Of course not.

> > E.g., if sched.h already sucks in kernel.h,
> > kernel.h still should be #included if the source (.c)
> > files uses any APIs or extern data from kernel.h.
> >
> > Does that help?
>
> no, sorry, doesn't help here ...
>
> nevertheless thanks,
> Herbert

-- 
~Randy
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