Re: [gentoo-dev] [PATCH] qt5-build.eclass: support sysroot builds

[James Le Cuirot]

On Fri, 27 Mar 2020 13:10:34 -0400
David Michael <fedora.dm0@×××××.com> wrote:

> I'd like to be able to install qt5 packages in a sysroot for staging,
> and this is an initial patch for it.  The pkg-config variables might not
> be required, but it seemed appropriate to pass the sysroot-configured
> versions through the build.  There are a few caveats:
>
>   - The upstream configure scripts do some bad things like this:
>     https://code.qt.io/cgit/qt/qtbase.git/tree/configure.pri#n363
>     That makes the build fail for systems using lib64 (e.g. amd64).  I'm
>     able to work around this by defining PKG_CONFIG_LIBDIR for dev-qt/*.

Indeed, that sucks. We should probably patch that out. I don't know
what it means where it says "or use -pkg-config to override this test",
do you? I suspect you could define PKG_CONFIG_LIBDIR=/ or anywhere that
simply exists and it will still work because our wrapper redefines that
variable anyway.

>   - This isn't for real cross-compiling.  There are places where it
>     tries to execute cross-compiled programs that I haven't investigated
>     yet, so this is only for building a sysroot for an architecture
>     compatible with the build system for now.

Understood. I did try to do cross-compiling with Qt4 once upon a time
and I did make a little headway but it wasn't fun.

>   - The qt packages depend on each other being installed in / as well as
>     the sysroot, so their ebuilds will need BDEPENDs added.

I imagine you'd at least need qtcore for qmake and moc. Probably not
the rest though?

>   - I've only gotten to testing a few packages that are dependencies of
>     other applications (like VLC), so I may be missing breakages.
>
> The patch basically just sets -sysroot when $SYSROOT is defined.  It
> also needs to set -extprefix to the normal prefix, since otherwise it
> would default to installing into /sysroot/prefix.  Is anyone involved in
> qt maintenance more experienced with this and able to comment?

I'm not the Qt guy but I am the cross guy. I'm not in a position to
test this right now but it looks good and I love the simplicity of it.
It's a hell of a lot simpler than Qt4 was. To be honest, we should be
setting QMAKE_PKG_CONFIG regardless.

-- 
James Le Cuirot (chewi)
Gentoo Linux Developer