Bug#917252: FTBFS building for armel,armhf on arm64

[Steve McIntyre]

Package: src:llvmlite
Version: 0.26.0-1
Severity: important

Hi!

I've been doing a full rebuild of the Debian archive, building all
source packages targeting armel and armhf using arm64 hardware. We are
planning in future to move all of our 32-bit armel/armhf builds to
using arm64 machines, so this rebuild is to identify packages that
might have problems with this configuration.

I've tried to build llvmlite for armel on top of arm64, and it's
failing in its test suite:

test_close (llvmlite.tests.test_binding.TestGlobalConstructors) ... ok
test_emit_assembly (llvmlite.tests.test_binding.TestGlobalConstructors)
Test TargetMachineRef.emit_assembly() ... ok
test_emit_object (llvmlite.tests.test_binding.TestGlobalConstructors)
Test TargetMachineRef.emit_object() ... ok
test_global_ctors_dtors (llvmlite.tests.test_binding.TestGlobalConstructors) ... LLVM ERROR: Program used external function '__aeabi_unwind_c
pp_pr0' which could not be resolved!
E: pybuild pybuild:338: test: plugin distutils failed with: exit code=1: cd /<<PKGBUILDDIR>>/.pybuild/cpython2_2.7_llvmlite/build; python2.7 
-m unittest discover -v 
dh_auto_test: pybuild --test -i python{version} -p 2.7 returned exit code 13
make: *** [debian/rules:8: build] Error 25
dpkg-buildpackage: error: debian/rules build subprocess returned exit status 2

Full log online at

  https://www.einval.com/debian/arm/rebuild-logs/armel/FAIL/llvmlite_0.26.0-1_armel.log

I can also see that the buildd arm-arm-01 (also an arm64 machine)
failed to build the package for armhf, with the same problem:

  https://buildd.debian.org/status/fetch.php?pkg=llvmlite&arch=armhf&ver=0.26.0-1&stamp=1543651733&raw=0

While this package seems to build fine for armel and armhf if built on
32-bit hardware, it appears there is possibly some misconfiguration
being auto-detected on arm64 hardware.

-- System Information:
Debian Release: 9.6
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-debug'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.9.0-8-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)