SonarLint reports the latter to be better:

std::scoped_lock basically provides the same feature as std::lock_guard,
but is more generic: It can lock several mutexes at the same time, with a
deadlock prevention mechanism (see {rule:cpp:S5524}). The equivalent code
to perform simultaneous locking with std::lock_guard is significantly more
complex. Therefore, it is simpler to use std::scoped_lock all the time,
even when locking only one mutex (there will be no performance impact).
Signed-off-by: Rosen Penev <rosenp@gmail.com>

The former was deprecated with C++14.

According to the C++11 and C++17 standards, both files are identical.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

Since we switched from autotools to Meson in commit
94592c14, we don't need to include
`config.h` early to properly enable large file support.  Meson passes
the required macros on the compiler command line instead of defining
them in `config.h`.

This means we can include `config.h` at any time, whenever we want to
check its macros, and there are no ordering constraints.

Make all uses of MusicChunk safe.

This tiny amount of overhead allows omitting the MusicBuffer in
Clear().

This eliminates some overhead, because the compiler doesn't need to
consider these functions throwing.

After we've been hit by Large File Support problems several times in
the past week (which only occur on 32 bit platforms, which I don't
have), this is yet another attempt to fix the issue.

Always assert that the audio format of the new chunk is valid.

This updates the copyright header to all be the same, which is
pretty much an update of where to mail request for a copy of the GPL
and the years of the MPD project. This also puts all committers under
'The Music Player Project' umbrella. These entries should go
individually in the AUTHORS file, for consistancy.

In !NDEBUG, remember which audio_format is stored in every chunk and
every pipe.  Check the audio_format of every new data block appended
to the music_chunk, and the format of every new chunk appended to the
music_pipe.

Added two assertions.

The value of music_chunk.next is undefined for a chunk returned by
music_pipe_shift().  For more pedantic debugging, poison the reference
before returning the chunk.

music_pipe_peek() is similar to music_pipe_shift(), but doesn't remove
the chunk.  This allows it to be used with a "const" music_pipe.

Turn the music_pipe into a simple music_chunk queue.  The music_chunk
allocation code is moved to music_buffer, and is now managed with a
linked list instead of a ring buffer.  Two separate music_pipe objects
are used by the decoder for the "current" and the "next" song, which
greatly simplifies the cross-fading code.