thread/Mutex: use `using` instead of making it a derived class

src/archive/ArchiveFile.hxx

 /*
- * Copyright 2003-2018 The Music Player Daemon Project
+ * Copyright 2003-2019 The Music Player Daemon Project
  * http://www.musicpd.org
  *
  * This program is free software; you can redistribute it and/or modify
@@ -21,8 +21,8 @@
 #define MPD_ARCHIVE_FILE_HXX
 
 #include "input/Ptr.hxx"
+#include "thread/Mutex.hxx"
 
-class Mutex;
 class ArchiveVisitor;
 
 class ArchiveFile {

src/input/InputPlugin.hxx

@@ -21,10 +21,10 @@
 #define MPD_INPUT_PLUGIN_HXX
 
 #include "Ptr.hxx"
+#include "thread/Mutex.hxx"
 #include "util/Compiler.h"
 
 struct ConfigBlock;
-class Mutex;
 class EventLoop;
 class RemoteTagScanner;
 class RemoteTagHandler;

src/input/LocalOpen.hxx

@@ -21,9 +21,9 @@
 #define MPD_INPUT_LOCAL_OPEN_HXX
 
 #include "Ptr.hxx"
+#include "thread/Mutex.hxx"
 
 class Path;
-class Mutex;
 
 /**
  * Open a "local" file.  This is a wrapper for the input plugins

src/input/plugins/ArchiveInputPlugin.hxx

@@ -21,9 +21,9 @@
 #define MPD_INPUT_ARCHIVE_HXX
 
 #include "input/Ptr.hxx"
+#include "thread/Mutex.hxx"
 
 class Path;
-class Mutex;
 
 InputStreamPtr
 OpenArchiveInputStream(Path path, Mutex &mutex);

src/input/plugins/CurlInputPlugin.hxx

@@ -21,12 +21,11 @@
 #define MPD_INPUT_CURL_HXX
 
 #include "input/Ptr.hxx"
+#include "thread/Mutex.hxx"
 
 #include <string>
 #include <map>
 
-class Mutex;
-
 extern const struct InputPlugin input_plugin_curl;
 
 /**

src/input/plugins/FileInputPlugin.hxx

@@ -21,9 +21,9 @@
 #define MPD_INPUT_FILE_HXX
 
 #include "input/Ptr.hxx"
+#include "thread/Mutex.hxx"
 
 class Path;
-class Mutex;
 
 InputStreamPtr
 OpenFileInputStream(Path path, Mutex &mutex);

src/lib/curl/Init.hxx

 /*
- * Copyright (C) 2008-2017 Max Kellermann <max.kellermann@gmail.com>
+ * Copyright 2008-2019 Max Kellermann <max.kellermann@gmail.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -30,7 +30,8 @@
 #ifndef CURL_INIT_HXX
 #define CURL_INIT_HXX
 
-class Mutex;
+#include "thread/Mutex.hxx"
+
 class EventLoop;
 class CurlGlobal;
 

src/lib/smbclient/Mutex.cxx

@@ -18,6 +18,5 @@
  */
 
 #include "Mutex.hxx"
-#include "thread/Mutex.hxx"
 
 Mutex smbclient_mutex;

src/lib/smbclient/Mutex.hxx

@@ -20,7 +20,7 @@
 #ifndef MPD_SMBCLIENT_MUTEX_HXX
 #define MPD_SMBCLIENT_MUTEX_HXX
 
-class Mutex;
+#include "thread/Mutex.hxx"
 
 /**
  * Since libsmbclient is not thread-safe, this mutex must be locked

src/output/Control.hxx

@@ -45,7 +45,6 @@ struct FilteredAudioOutput;
 struct MusicChunk;
 struct ConfigBlock;
 class MusicPipe;
-class Mutex;
 class Mixer;
 class AudioOutputClient;
 

src/output/Source.hxx

@@ -26,6 +26,7 @@
 #include "ReplayGainMode.hxx"
 #include "pcm/PcmBuffer.hxx"
 #include "pcm/PcmDither.hxx"
+#include "thread/Mutex.hxx"
 #include "util/ConstBuffer.hxx"
 
 #include <utility>
@@ -36,7 +37,6 @@
 
 struct MusicChunk;
 struct Tag;
-class Mutex;
 class Filter;
 class PreparedFilter;
 

src/playlist/PlaylistAny.hxx

@@ -20,11 +20,11 @@
 #ifndef MPD_PLAYLIST_ANY_HXX
 #define MPD_PLAYLIST_ANY_HXX
 
+#include "thread/Mutex.hxx"
 #include "config.h"
 
 #include <memory>
 
-class Mutex;
 class SongEnumerator;
 class Storage;
 

src/playlist/PlaylistMapper.hxx

@@ -20,11 +20,11 @@
 #ifndef MPD_PLAYLIST_MAPPER_HXX
 #define MPD_PLAYLIST_MAPPER_HXX
 
+#include "thread/Mutex.hxx"
 #include "config.h"
 
 #include <memory>
 
-class Mutex;
 class SongEnumerator;
 class Storage;
 

src/playlist/PlaylistPlugin.hxx

@@ -21,10 +21,10 @@
 #define MPD_PLAYLIST_PLUGIN_HXX
 
 #include "input/Ptr.hxx"
+#include "thread/Mutex.hxx"
 
 struct ConfigBlock;
 struct Tag;
-class Mutex;
 class SongEnumerator;
 
 struct playlist_plugin {

src/playlist/PlaylistRegistry.hxx

@@ -21,10 +21,10 @@
 #define MPD_PLAYLIST_REGISTRY_HXX
 
 #include "input/Ptr.hxx"
+#include "thread/Mutex.hxx"
 #include "util/Compiler.h"
 
 struct ConfigData;
-class Mutex;
 class SongEnumerator;
 
 extern const struct playlist_plugin *const playlist_plugins[];

src/playlist/PlaylistStream.hxx

@@ -20,11 +20,11 @@
 #ifndef MPD_PLAYLIST_STREAM_HXX
 #define MPD_PLAYLIST_STREAM_HXX
 
+#include "thread/Mutex.hxx"
 #include "util/Compiler.h"
 
 #include <memory>
 
-class Mutex;
 class SongEnumerator;
 class Path;
 

src/tag/Aiff.hxx

@@ -25,12 +25,11 @@
 #ifndef MPD_AIFF_HXX
 #define MPD_AIFF_HXX
 
-#include <mutex>
+#include "thread/Mutex.hxx"
 
 #include <stddef.h>
 
 class InputStream;
-class Mutex;
 
 /**
  * Seeks the AIFF file to the ID3 chunk.

src/tag/Riff.hxx

@@ -25,11 +25,10 @@
 #ifndef MPD_RIFF_HXX
 #define MPD_RIFF_HXX
 
-#include <mutex>
+#include "thread/Mutex.hxx"
 
 #include <stddef.h>
 
-class Mutex;
 class InputStream;
 
 /**

src/thread/Mutex.hxx

@@ -35,12 +35,12 @@
 #ifdef _WIN32
 
 #include "CriticalSection.hxx"
-class Mutex : public CriticalSection {};
+using Mutex = CriticalSection;
 
 #else
 
 #include "PosixMutex.hxx"
-class Mutex : public PosixMutex {};
+using Mutex = PosixMutex;
 
 #endif