Some "ar" implementations don't allow empty archives, and failed to
build it.  The real reason (which is hidden with GNU binutils) is that
our Makefile.am was incorrect, and didn't completely disable
libxiph.a.

See https://bugs.musicpd.org/view.php?id=4526

Rename struct Encoder to PreparedEncoder, and add a new (abstract)
class Encoder which represents one encoder instance.

Will be needed to compile libxiph.a.

release v0.19.15

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@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

> In file included from src/decoder/DecoderBuffer.cxx:21:0:
> src/decoder/DecoderBuffer.hxx:41:20: error: 'uint8_t' was not declared in this scope
>   DynamicFifoBuffer<uint8_t> buffer;
>                     ^
> src/decoder/DecoderBuffer.hxx:41:27: error: template argument 1 is invalid
>   DynamicFifoBuffer<uint8_t> buffer;
>                            ^
> src/decoder/DecoderBuffer.hxx: In member function 'void DecoderBuffer::Clear()':
> src/decoder/DecoderBuffer.hxx:61:10: error: request for member 'Clear' in '((DecoderBuffer*)this)->DecoderBuffer::buffer', which is of non-class type 'int'
>    buffer.Clear();
>           ^
> src/decoder/DecoderBuffer.hxx: In member function 'size_t DecoderBuffer::GetAvailable() const':
> src/decoder/DecoderBuffer.hxx:78:17: error: request for member 'GetAvailable' in '((const DecoderBuffer*)this)->DecoderBuffer::buffer', which is of non-class type 'const int'
>    return buffer.GetAvailable();
>                  ^
> src/decoder/DecoderBuffer.hxx: In member function 'ConstBuffer<void> DecoderBuffer::Read() const':
> src/decoder/DecoderBuffer.hxx:87:19: error: request for member 'Read' in '((const DecoderBuffer*)this)->DecoderBuffer::buffer', which is of non-class type 'const int'
>    auto r = buffer.Read();
>                    ^
> src/decoder/DecoderBuffer.hxx:88:27: error: could not convert '{<expression error>, <expression error>}' from '<brace-enclosed initializer list>' to 'ConstBuffer<void>'
>    return { r.data, r.size };
>                            ^
> src/decoder/DecoderBuffer.hxx: In member function 'void DecoderBuffer::Consume(size_t)':
> src/decoder/DecoderBuffer.hxx:105:10: error: request for member 'Consume' in '((DecoderBuffer*)this)->DecoderBuffer::buffer', which is of non-class type 'int'
>    buffer.Consume(nbytes);
>           ^

This seems to be caused by a lacking include, fixed by the below patch.

I'm unsure what made this appear now, though, compiler and toolchain
libraries seem to be the same upstream versions that built 0.19.14-1
just fine in late March.

A complete list which replaces the incomplete list in the mpd.conf
manpage.