Source: mpd
Version: 0.19.14-2
Severity: important
Justification: fails to build form source (but built in the past)
Tags: patch
User: [email protected]
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
Index: mpd-0.19.14/test/test_byte_reverse.cxx
===================================================================
--- mpd-0.19.14.orig/test/test_byte_reverse.cxx
+++ mpd-0.19.14/test/test_byte_reverse.cxx
@@ -49,9 +49,9 @@ CPPUNIT_TEST_SUITE_REGISTRATION(ByteReve
void
ByteReverseTest::TestByteReverse2()
{
- static const char src[] = "123456";
+ static const char src[] alignas(uint16_t) = "123456";
static const char result[] = "214365";
- static uint8_t dest[ARRAY_SIZE(src)];
+ static uint8_t dest[ARRAY_SIZE(src)] alignas(uint16_t);
reverse_bytes(dest, (const uint8_t *)src,
(const uint8_t *)(src + ARRAY_SIZE(src) - 1), 2);
@@ -73,9 +73,9 @@ ByteReverseTest::TestByteReverse3()
void
ByteReverseTest::TestByteReverse4()
{
- static const char src[] = "12345678";
+ static const char src[] alignas(uint32_t) = "12345678";
static const char result[] = "43218765";
- static uint8_t dest[ARRAY_SIZE(src)];
+ static uint8_t dest[ARRAY_SIZE(src)] alignas(uint32_t);
reverse_bytes(dest, (const uint8_t *)src,
(const uint8_t *)(src + ARRAY_SIZE(src) - 1), 4);
