use [[gnu::...]] attributes

src/db/plugins/ProxyDatabasePlugin.cxx

@@ -16,7 +16,6 @@
 #include "song/UriSongFilter.hxx"
 #include "song/BaseSongFilter.hxx"
 #include "song/TagSongFilter.hxx"
-#include "util/Compiler.h"
 #include "config/Block.hxx"
 #include "tag/Builder.hxx"
 #include "tag/Tag.hxx"
@@ -265,7 +264,7 @@ ProxySong::ProxySong(const mpd_song *song)
 	tag_builder.Commit(tag2);
 }
 
-gcc_const
+[[gnu::const]]
 static enum mpd_tag_type
 Convert(TagType tag_type) noexcept
 {
@@ -694,7 +693,7 @@ Visit(struct mpd_connection *connection,
 		      visit_directory, visit_song, visit_playlist);
 }
 
-gcc_pure
+[[gnu::pure]]
 static bool
 Match(const SongFilter *filter, const LightSong &song) noexcept
 {
@@ -864,7 +863,7 @@ try {
 	throw;
 }
 
-gcc_pure
+[[gnu::pure]]
 static bool
 IsFilterSupported(const ISongFilter &f) noexcept
 {
@@ -890,7 +889,7 @@ IsFilterSupported(const ISongFilter &f) noexcept
 		return false;
 }
 
-gcc_pure
+[[gnu::pure]]
 static bool
 IsFilterFullySupported(const SongFilter &filter,
 		       const struct mpd_connection *connection) noexcept
@@ -908,7 +907,7 @@ IsFilterFullySupported(const SongFilter &filter,
 			   [](const auto &item) { return IsFilterSupported(*item); });
 }
 
-gcc_pure
+[[gnu::pure]]
 static bool
 IsFilterFullySupported(const SongFilter *filter,
 		       const struct mpd_connection *connection) noexcept
@@ -917,7 +916,7 @@ IsFilterFullySupported(const SongFilter *filter,
 		IsFilterFullySupported(*filter, connection);
 }
 
-gcc_pure
+[[gnu::pure]]
 static bool
 IsSortSupported(TagType tag_type,
 		const struct mpd_connection *connection) noexcept
@@ -939,7 +938,7 @@ IsSortSupported(TagType tag_type,
 	return Convert(tag_type) != MPD_TAG_COUNT;
 }
 
-gcc_pure
+[[gnu::pure]]
 static DatabaseSelection
 CheckSelection(DatabaseSelection selection,
 	       struct mpd_connection *connection) noexcept

src/db/plugins/simple/Directory.cxx

@@ -193,7 +193,7 @@ Directory::FindSong(std::string_view name_utf8) const noexcept
 	return nullptr;
 }
 
-gcc_pure
+[[gnu::pure]]
 static bool
 directory_cmp(const Directory &a, const Directory &b) noexcept
 {

src/db/plugins/simple/DirectorySave.cxx

@@ -25,7 +25,7 @@
 #define DIRECTORY_BEGIN "begin: "
 #define DIRECTORY_END "end: "
 
-gcc_const
+[[gnu::const]]
 static const char *
 DeviceToTypeString(unsigned device) noexcept
 {
@@ -44,7 +44,7 @@ DeviceToTypeString(unsigned device) noexcept
 	}
 }
 
-gcc_pure
+[[gnu::pure]]
 static unsigned
 ParseTypeString(const char *type) noexcept
 {

src/db/plugins/simple/SimpleDatabasePlugin.cxx

@@ -248,7 +248,7 @@ SimpleDatabase::ReturnSong([[maybe_unused]] const LightSong *song) const noexcep
 	}
 }
 
-gcc_const
+[[gnu::const]]
 static DatabaseSelection
 CheckSelection(DatabaseSelection selection) noexcept
 {

src/db/plugins/simple/Song.cxx

@@ -47,7 +47,7 @@ Song::GetURI() const noexcept
 /**
  * Path name traversal of a #Directory.
  */
-gcc_pure
+[[gnu::pure]]
 static const Directory *
 FindTargetDirectory(const Directory &base, std::string_view path) noexcept
 {
@@ -69,7 +69,7 @@ FindTargetDirectory(const Directory &base, std::string_view path) noexcept
 /**
  * Path name traversal of a #Song.
  */
-gcc_pure
+[[gnu::pure]]
 static const Song *
 FindTargetSong(const Directory &_directory, std::string_view target) noexcept
 {

src/db/plugins/simple/SongSort.cxx

@@ -60,7 +60,7 @@ compare_tag_item(const Tag &a, const Tag &b, TagType type) noexcept
 }
 
 /* Only used for sorting/searchin a songvec, not general purpose compares */
-gcc_pure
+[[gnu::pure]]
 static bool
 song_cmp(const Song &a, const Song &b) noexcept
 {

src/db/plugins/upnp/UpnpDatabasePlugin.cxx

@@ -563,7 +563,7 @@ UpnpDatabase::VisitServer(const ContentDirectoryService &server,
 	}
 }
 
-gcc_const
+[[gnu::const]]
 static DatabaseSelection
 CheckSelection(DatabaseSelection selection) noexcept
 {