[Pkg-mpd-maintainers] Bug#822848: mpd FTBFS on Alpha; misaligned arrays in the test suite

[Michael Cree]

Source: mpd
Version: 0.19.14-2
Severity: important
Justification: fails to build form source (but built in the past)
Tags: patch
User: debian-alpha at lists.debian.org
Usertags: alpha

mpd FTBFS on Alpha with a failure in the test suite [1]:

FAIL: test/test_byte_reverse
============================

.F...


!!!FAILURES!!!
Test Results:
Run:  4   Failures: 1   Errors: 0


1) test: ByteReverseTest::TestByteReverse2 (F) line: 58 test/test_byte_reverse.cxx
assertion failed
- Expression: strcmp(result, (const char *)dest) == 0


This occurs because the test suite (in test/test_byte_reversal.cxx)
allocates static char arrays and passes the char arrays to functions
whose respective arguments were declared to be uint16_t *, etc., in
the main code.

This is in the realm of undefined behaviour on architectures with
strict memory alignment requirements.  Although the test only fails
on Alpha (because Alpha has a particular CPU load instruction that
gcc likes to use to add bugs ..., ahem,  optimise the code on the
assumption of alignment) it is potentially a latent bug for other
architectures with strict alignment requirements.

Since the code is compiled with the c++11 standard I attach a patch
that modifies the test suite to align the non-compliant strings with
the alignas() attribute.  The test suite now passes on Alpha with
that patch.

Cheers
Michael

[1] https://buildd.debian.org/status/fetch.php?pkg=mpd&arch=alpha&ver=0.19.14-2&stamp=1461542099
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