[PATCH v3 6/7] buildtools/chkincs: use a staging directory for headers

[Morten Brørup]

> From: Bruce Richardson [mailto:bruce.richardson at intel.com]
> Sent: Thursday, 25 September 2025 11.32
> 
> On Thu, Sep 25, 2025 at 10:42:47AM +0200, David Marchand wrote:
> > Hello Bruce,
> >
> > On Thu, 25 Sept 2025 at 10:00, Bruce Richardson
> > <bruce.richardson at intel.com> wrote:
> > >
> > > On Wed, Sep 24, 2025 at 07:25:34PM +0200, David Marchand wrote:
> > > > A problem with the current headers check is that it relies on
> > > > meson dependencies objects that come with their
> include_directories
> > > > directives, and all of those point at the library / driver
> sources.
> > > >
> > > > This means that we won't detect a public header including a
> private
> > > > (as in, not exported) header, or a driver only header.
> > > >
> > > > To address this issue, a staging directory is added and every
> header
> > > > is copied to it.
> > > >
> > > > Drivers and library headers are staged to two different
> directories
> > > > and the check is updated accordingly.
> > > >
> > > > Signed-off-by: David Marchand <david.marchand at redhat.com>
> > >
> > > In general looks ok to me.
> > > One small comment though - can we not have "staging" as a top-level
> > > directory, but instead hide it inside the buildtools directory, or
> even the
> > > chkincs directory? I dislike having too many subdirectories
> directly off
> > > the root of the project, especially ones purely for internal
> tooling.
> >
> > Well, at first I was trying to change the whole build process iow
> rely
> > only on the staging directory and remove all the include_directories:
> > directives from the declare_dependency() objects.
> > Libraries and apps were ok, but there were a *lot* of complications
> > with drivers (what a *huge mess*, especially for NXP drivers with
> > "compat.h" includes, and Marvell drivers to a smaller extent).
> > I may retry in the future with some AI tool that will brute force
> this :-).
> >
> > For now, I gave up but did not reconsider the location of the staging
> part.
> > Moving to buildtools is indeed saner as it is only for the check now,
> > and I can also make this staging stuff dependent on the
> check_includes
> > option now.
> >
> 
> I wonder should we just consider making chkincs an install-time job
> rather
> than a build-time one? We could look to build chkincs using a custom
> install script (meson.add_install_script) after the header copies are
> already done for us. That should cut down on the complexity within the
> build system, but it does mean an additional install step to a
> temporary
> directory to get it to run. However, for use in our CI I don't see why
> having an install step with DEST_DIR set to /tmp shouldn't be feasible.

Such a temporary directory should be local to the developer's working directory.
(The CI might have different needs; that's not what I'm commenting.)

Furthermore, test building for upstreaming should remain simple. I use something like:
meson setup -Dplatform=generic -Dcheck_includes=true build
ninja -C build

Disclaimer: Haven't really followed this discussion, so maybe my comments above are irrelevant.