[PATCH wayland v1 1/1] wayland-scanner.pc.in: prepend pc_sysrootdir

[Arnaud Vrac]

On Fri, Sep 16, 2016 at 5:19 PM, Joe Konno <joe.konno at linux.intel.com>
wrote:

> On Fri, 16 Sep 2016 10:53:32 +0300
> Pekka Paalanen <ppaalanen at gmail.com> wrote:
>
> > On Thu, 15 Sep 2016 15:22:12 -0700
> > Joe Konno <joe.konno at linux.intel.com> wrote:
> >
> > > From: Joe Konno <joe.konno at intel.com>
> > >
> > > In a cross-compilation environment with packages depending on
> > > wayland-scanner, ensure the path to wayland-scanner is correct. Without
> > > this patch, the path will _not_ point to the target environment but to
> > > the host's, potentially leading to breakage.
> > >
> > > https://bugs.freedesktop.org/show_bug.cgi?id=97828
> > >
> > > Signed-off-by: Joe Konno <joe.konno at intel.com>
> > > ---
> > >  src/wayland-scanner.pc.in | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/src/wayland-scanner.pc.in b/src/wayland-scanner.pc.in
> > > index 7b2a4c92e0e3..ec11a0bc982c 100644
> > > --- a/src/wayland-scanner.pc.in
> > > +++ b/src/wayland-scanner.pc.in
> > > @@ -2,7 +2,7 @@ prefix=@prefix@
> > >  exec_prefix=@exec_prefix@
> > >  datarootdir=@datarootdir@
> > >  pkgdatadir=@datadir@/@PACKAGE@
> > > -wayland_scanner=@bindir@/wayland-scanner
> > > +wayland_scanner=${pc_sysrootdir}/@bindir@/wayland-scanner
> > >
> > >  Name: Wayland Scanner
> > >  Description: Wayland scanner
> >
> > Hi,
> >
> > ok, so pc_sysrootdir points to the sysroot. I would just like to
> > confirm that this really does what you intend. wayland-scanner is a
> > build tool to be run on the host. Such tools get installed into the
> > sysroot even when compiled for the host, not the target, yes?
> >
> > I read both http://dev.gentoo.org/~mgorny/pkg-config-spec.html and
> > https://autotools.io/pkgconfig/cross-compiling.html but couldn't
> > actually understand what is going on, perhaps because I never
> > cross-compile.
> >
> > Hence I cannot offer a Reviewed-by, but I can offer:
> > Acked-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> >
> > (Not for the 1.12.0 release.)
> >
> > Are you using binary-compatible arches for both host and target? I'd
> > like to see a test on a setup where the binaries are completely
> > incompatible so that the host != target difference is obvious.
>
> I'm struggling with this particular cross-compilation scenario as well, as
> there's a fair bit of wonky overhead involved in the build process I'm
> dealing
> with. Figured I'd introduce the patch and solicit feedback early while I
> continue digging.
>
> Your points are fair and the feedback's appreciated. I'll see about testing
> this out a bit more with an incompatible binary target-- right now my host
> is
> Intel-based and my target is also Intel-based.
>
> I'll reply back once I feel convinced one way or the other. ^_^
>

Hi Joe,

I believe your patch is not right, as pq says the sysroot normally contains
the code compiled for the target, which might not be compatible with the
host.

I think the proper way to do this is to compile wayland for the host
separately, and use ${CHOST}-pkg-config instead of pkg-config to get the
wayland-scanner path. In practice you would call
x86_64-linux-gnu-pkg-config --variable=wayland_scanner. The
x86_64-linux-gnu-pkg-config utility will look for pkgconfig files in the
host sysroot, instead of the target sysroot, allowing this use case to work.

Unfortunately not many packages do this correctly...

Regards,
Arnaud
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