[yocto] Python module and build_ext args

[Craig McQueen]

I wrote:
> Khem Raj wrote:
> > On Thu, Aug 24, 2017 at 9:42 PM, Craig McQueen
> > <craig.mcqueen at innerrange.com> wrote:
> > > Khem Raj wrote:
> > > On Thu, Aug 24, 2017 at 6:48 PM Craig McQueen
> > > <craig.mcqueen at innerrange.com>
> > > wrote:
> > >
> > > I wrote:
> > >> I'm trying to make a recipe for python3-uvloop, using setuptools3.
> > >>
> > >> The Python 3 uvloop module depends on libuv. It bundles a version
> > >> of libuv, and setup.py tries to build it, but it doesn't work well
> > >> for cross-compilation.
> > >> However, it also provides a build_ext parameter
> > >> "--use-system-libuv", which seems to work when I try running it
> > >> manually in devshell. (I have made a suitable recipe for libuv and
> > >> added libuv to DEPENDS.)
> > >>
> > >> How can I specify the "--use-system-libuv" parameter for build_ext
> > >> in the python3-uvloop recipe? I see a reference to
> > >> DISTUTILS_BUILD_EXT_ARGS, but it doesn't seem to be functional.
> > >
> > >
> > > I see DISTUTILS_BUILD_EXT_ARGS was submitted in this patch:
> > > https://patchwork.openembedded.org/patch/66071/
> > >
> > > However, in the Yocto poky repository, I see commit
> > > 0221af0f4ee9e8bfb8796841bdf806e38bc600c6 which appears to be a
> > broken
> > > version of the above patch with the separate build_ext step not
> > > actually executed with the DISTUTILS_BUILD_EXT_ARGS parameters.
> > >
> > >
> > >
> > > You did not explain broken in which sense ?
> > >
> > >
> > >
> > > It is broken in the sense that: The separate build_ext step is not
> > > actually executed with the DISTUTILS_BUILD_EXT_ARGS parameters. The
> > > original patch submission contained:
> > >
> > >
> > >
> > >           STAGING_INCDIR=${STAGING_INCDIR} \
> > >
> > >           STAGING_LIBDIR=${STAGING_LIBDIR} \
> > >
> > >           BUILD_SYS=${BUILD_SYS} HOST_SYS=${HOST_SYS} \
> > >
> > > -         ${STAGING_BINDIR_NATIVE}/${PYTHON_PN}-
> native/${PYTHON_PN}
> > setup.py
> > > build ${DISTUTILS_BUILD_ARGS} || \
> > >
> > > +         ${STAGING_BINDIR_NATIVE}/${PYTHON_PN}-
> native/${PYTHON_PN}
> > > + setup.py
> > > \
> > >
> > > +         build_ext --include-dirs
> > > ${STAGING_INCDIR}/${PYTHON_DIR}${PYTHON_ABI} \
> > >
> > > +         --library-dirs ${STAGING_LIBCDIR}/${PYTHON_DIR} \
> > >
> > > +         ${DISTUTILS_BUILD_EXT_ARGS} \
> > >
> > > +         build ${DISTUTILS_BUILD_ARGS} || \
> > >
> > > +         ${STAGING_BINDIR_NATIVE}/${PYTHON_PN}-
> native/${PYTHON_PN}
> > > + setup.py
> > > build_ext ${DISTUTILS_BUILD_ARGS} || \
> > >
> > >           bbfatal "${PYTHON_PN} setup.py build_ext execution failed."
> > >
> > > }
> > >
> > >
> > >
> > > However that part of the patch is not present in commit
> > > 0221af0f4ee9e8bfb8796841bdf806e38bc600c6.
> > >
> >
> > IIRC there were some breakages with this but it was long time ago. Can
> > you appy this change and test it out ?
> 
> I tried applying the change manually. The Yocto do_compile step succeeded.
> But then the do_install step still failed. It seems that the do_install step
> (which runs setup.py install) still runs the setup.py build_ext step a second
> time, without the extra option I was trying to use.
> 
> I'm not familiar enough with the working of python3 setup.py to know why
> the install step re-runs the build_ext step a second time.

I wasn't able to find an elegant solution for DISTUTILS_BUILD_EXT_ARGS. I ended up getting a working python3-uvloop recipe a different way, using two patches to the setup.py.

I have posted to the uvloop project regarding this:

https://github.com/MagicStack/uvloop/issues/104

-- 
Craig McQueen