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

src/storage/plugins/CurlStorage.cxx

@@ -203,7 +203,7 @@ ParseU64(const char *s, size_t length) noexcept
 	return ParseU64(std::string(s, length).c_str());
 }
 
-gcc_pure
+[[gnu::pure]]
 static bool
 IsXmlContentType(const char *content_type) noexcept
 {
@@ -211,7 +211,7 @@ IsXmlContentType(const char *content_type) noexcept
 		StringStartsWith(content_type, "application/xml");
 }
 
-gcc_pure
+[[gnu::pure]]
 static bool
 IsXmlContentType(const Curl::Headers &headers) noexcept
 {
@@ -456,7 +456,7 @@ CurlStorage::GetInfo(std::string_view uri_utf8, [[maybe_unused]] bool follow)
 	return HttpGetInfoOperation(*curl, uri.c_str()).Perform();
 }
 
-gcc_pure
+[[gnu::pure]]
 static std::string_view
 UriPathOrSlash(const char *uri) noexcept
 {
@@ -494,7 +494,7 @@ private:
 	 * Convert a "href" attribute (which may be an absolute URI)
 	 * to the base file name.
 	 */
-	gcc_pure
+	[[gnu::pure]]
 	std::string_view HrefToEscapedName(const char *href) const noexcept {
 		std::string_view path = uri_get_path(href);
 		if (path.data() == nullptr)

src/storage/plugins/LocalStorage.hxx

@@ -4,8 +4,6 @@
 #ifndef MPD_STORAGE_LOCAL_HXX
 #define MPD_STORAGE_LOCAL_HXX
 
-#include "util/Compiler.h"
-
 #include <memory>
 
 struct StoragePlugin;
@@ -14,7 +12,6 @@ class Path;
 
 extern const StoragePlugin local_storage_plugin;
 
-gcc_nonnull_all
 std::unique_ptr<Storage>
 CreateLocalStorage(Path base_fs);
 

src/storage/plugins/NfsStorage.cxx

@@ -288,7 +288,7 @@ NfsStorage::GetInfo(std::string_view uri_utf8, bool follow)
 	return operation.GetInfo();
 }
 
-gcc_pure
+[[gnu::pure]]
 static bool
 SkipNameFS(PathTraitsFS::const_pointer name) noexcept
 {

src/storage/plugins/SmbclientStorage.cxx

@@ -133,7 +133,7 @@ SmbclientStorage::OpenDirectory(std::string_view uri_utf8)
 							  handle);
 }
 
-gcc_pure
+[[gnu::pure]]
 static bool
 SkipNameFS(PathTraitsFS::const_pointer name) noexcept
 {