Bug#1003165: scikit-learn in unstable FTBFS on arm64, armel, armhf, i386, ppc64el and s390x

[Andreas Tille]

Hi,

Am Wed, Feb 16, 2022 at 12:09:23PM +0100 schrieb John Paul Adrian Glaubitz:
> 
> So, I have skimmed over the build logs and one of the main issues is the use of
> -march flags to enforce a certain baseline [1]:
> 
> powerpc64le-linux-gnu-gcc: error: unrecognized command-line option ‘-march=native’; did you mean ‘-mcpu=native’?
> 
> This is a policy violation and must be fixed in any case. Blacklisting architectures
> is not enough in this case as forcing the baseline of the buildds can lead to code
> that won't run on the user's machines.

I confirm this is a problem and the critical string can also be found in
the amd64 build log[2]:

...
running build_clib
customize UnixCCompiler
customize UnixCCompiler using build_clib
CCompilerOpt.cc_test_flags[1013] : testing flags (-march=native)
C compiler: x86_64-linux-gnu-gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O2 -Wall -g -fstack-protector-strong -Wformat -Werror=format-security -g -fwrapv -O2 -g -O2 -ffile-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC

creating /tmp/tmpk22ehoi2/usr
creating /tmp/tmpk22ehoi2/usr/lib
creating /tmp/tmpk22ehoi2/usr/lib/python3
creating /tmp/tmpk22ehoi2/usr/lib/python3/dist-packages
creating /tmp/tmpk22ehoi2/usr/lib/python3/dist-packages/numpy
creating /tmp/tmpk22ehoi2/usr/lib/python3/dist-packages/numpy/distutils
creating /tmp/tmpk22ehoi2/usr/lib/python3/dist-packages/numpy/distutils/checks
compile options: '-c'
extra options: '-march=native'
CCompilerOpt.cc_test_flags[1013] : testing flags (-O3)
C compiler: x86_64-linux-gnu-gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O2 -Wall -g -fstack-protector-strong -Wformat -Werror=format-security -g -fwrapv -O2 -g -O2 -ffile-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC
...


I admit I'm not sure at what point / what tool might inject this string and
I'm also not sure whether the option -march=native is really used in the
amd64 case.

Kind regards

     Andreas.

> > [1] https://buildd.debian.org/status/fetch.php?pkg=scikit-learn&arch=ppc64el&ver=1.0.2-1&stamp=1644956229&raw=0

[2] https://buildd.debian.org/status/fetch.php?pkg=scikit-learn&arch=amd64&ver=1.0.2-1&stamp=1644952702&raw=0

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