more [[gnu::...]] attributes

src/player/Control.hxx

@@ -326,7 +326,7 @@ public:
 	 */
 	std::unique_ptr<DetachedSong> LockReadTaggedSong() noexcept;
 
-	gcc_pure
+	[[gnu::pure]]
 	PlayerStatus LockGetStatus() noexcept;
 
 	PlayerState GetState() const noexcept {
@@ -338,7 +338,7 @@ public:
 		bool has_next_song;
 	};
 
-	gcc_pure
+	[[gnu::pure]]
 	SyncInfo LockGetSyncInfo() const noexcept {
 		const std::lock_guard<Mutex> protect(mutex);
 		return {state, next_song != nullptr};

src/player/CrossFade.hxx

@@ -21,7 +21,6 @@
 #define MPD_CROSSFADE_HXX
 
 #include "Chrono.hxx"
-#include "util/Compiler.h"
 
 struct AudioFormat;
 class SignedSongTime;
@@ -61,7 +60,7 @@ struct CrossFadeSettings {
 	 * @return the number of chunks for crossfading, or 0 if cross fading
 	 * should be disabled for this song change
 	 */
-	gcc_pure
+	[[gnu::pure]]
 	unsigned Calculate(SignedSongTime total_time,
 			   float replay_gain_db, float replay_gain_prev_db,
 			   const char *mixramp_start,

src/player/Outputs.hxx

@@ -22,7 +22,6 @@
 
 #include "MusicChunkPtr.hxx"
 #include "Chrono.hxx"
-#include "util/Compiler.h"
 
 struct AudioFormat;
 struct MusicChunk;
@@ -107,7 +106,7 @@ public:
 	 * chunk.  A negative value is returned when no chunk has been
 	 * finished yet.
 	 */
-	gcc_pure
+	[[gnu::pure]]
 	virtual SignedSongTime GetElapsedTime() const noexcept = 0;
 };