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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Fri, 19 Nov 2021 17:27:17 +0100
Message-ID: <CAK8P3a3O1KLzxSTn1xqi2HjUVw2Utf6m5PZWd1ns7xsExxbJOA@mail.gmail.com>
Subject: Re: [PATCH 00/17] Add memberof(), split some headers, and slightly
 simplify code
To:     "Alejandro Colomar (man-pages)" <alx.manpages@gmail.com>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
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On Fri, Nov 19, 2021 at 5:22 PM Alejandro Colomar (man-pages)
<alx.manpages@gmail.com> wrote:
> On 11/19/21 17:18, Arnd Bergmann wrote:
> > On Fri, Nov 19, 2021 at 5:10 PM Andy Shevchenko
> > <andriy.shevchenko@linux.intel.com> wrote:
> >> On Fri, Nov 19, 2021 at 04:57:46PM +0100, Arnd Bergmann wrote:
> >
> >>> The main problem with this approach is that as soon as you start
> >>> actually reducing the unneeded indirect includes, you end up with
> >>> countless .c files that no longer build because they are missing a
> >>> direct include for something that was always included somewhere
> >>> deep underneath, so I needed a second set of scripts to add
> >>> direct includes to every .c file.
> >>
> >> Can't it be done with cocci support?
> >
> > There are many ways of doing it, but they all tend to suffer from the
> > problem of identifying which headers are actually needed based on
> > the contents of a file, and also figuring out where to put the extra
> > #include if there are complex #ifdefs.
> >
> > For reference, see below for the naive pattern matching I tried.
> > This is obviously incomplete and partially wrong.
>
> FYI, if you may not know the tool,
> theres include-what-you-use(1) (a.k.a. iwyu(1))[1],
> although it is still not mature,
> and I'm helping improve it a bit.

Yes, I know that one, I tried using it as well, but it did not really
scale to the size of the kernel as it requires having all files to use
the correct set of #include, and to know about all the definitions.

       Arnd