replace __UNUSED with maybe_unused

Standard C++17.

Signed-off-by: Rosen Penev <[email protected]>

configure.ac

@@ -105,11 +105,6 @@ AC_SUBST(LIBTORRENT_CFLAGS)
 
 AC_DEFINE(HAVE_CONFIG_H, 1, true if config.h was included)
 
-CC_ATTRIBUTE_UNUSED(
-  AC_DEFINE([__UNUSED], [__attribute__((unused))], [Wrapper around unused attribute]),
-  AC_DEFINE([__UNUSED], [], [Null-wrapper if unused attribute is unsupported])
-)
-
 AC_CONFIG_FILES([
 	libtorrent.pc
 	Makefile

rak/allocators.h

@@ -77,7 +77,7 @@ class cacheline_allocator {
 
   static pointer alloc_size(size_type size) {
     pointer ptr = NULL;
-    int __UNUSED result = posix_memalign((void**)&ptr, LT_SMP_CACHE_BYTES, size);
+    [[maybe_unused]] int result = posix_memalign((void**)&ptr, LT_SMP_CACHE_BYTES, size);
 
     return ptr;
   }

rak/string_manip.h

@@ -143,8 +143,8 @@ class split_iterator_t {
     return *this;
   }
 
-  bool operator == (__UNUSED const split_iterator_t& itr) const { return m_pos == m_seq->end(); }
-  bool operator != (__UNUSED const split_iterator_t& itr) const { return m_pos != m_seq->end(); }
+  bool operator == ([[maybe_unused]] const split_iterator_t& itr) const { return m_pos == m_seq->end(); }
+  bool operator != ([[maybe_unused]] const split_iterator_t& itr) const { return m_pos != m_seq->end(); }
 
 private:
   const Sequence* m_seq;
@@ -161,7 +161,7 @@ split_iterator(const Sequence& seq, typename Sequence::value_type delim) {
 
 template <typename Sequence>
 inline split_iterator_t<Sequence>
-split_iterator(__UNUSED const Sequence& seq) {
+split_iterator([[maybe_unused]] const Sequence& seq) {
   return split_iterator_t<Sequence>();
 }
 

src/data/chunk.cc

@@ -193,10 +193,10 @@ Chunk::preload(uint32_t position, uint32_t length, bool useAdvise) {
 
     } else {
       for (char* first = (char*)data.first, *last = (char*)data.first + data.second; first < last; first += 4096)
-        volatile char __UNUSED touchChunk = *(char*)data.first;
+        [[maybe_unused]] volatile char touchChunk = *(char*)data.first;
 
       // Make sure we touch the last page in the range.
-      volatile char __UNUSED touchChunk = *((char*)data.first + data.second - 1);
+      [[maybe_unused]] volatile char ouchChunk = *((char*)data.first + data.second - 1);
     }
 
   } while (itr.next());

src/download/chunk_selector.cc

@@ -87,7 +87,7 @@ ChunkSelector::update_priorities() {
 }
 
 uint32_t
-ChunkSelector::find(PeerChunks* pc, __UNUSED bool highPriority) {
+ChunkSelector::find(PeerChunks* pc, [[maybe_unused]] bool highPriority) {
   // This needs to be re-enabled.
   if (m_position == invalid_chunk)
     return invalid_chunk;

src/torrent/poll_kqueue.cc

@@ -394,15 +394,15 @@ PollKQueue::remove_error(Event* event) {
 #else // USE_QUEUE
 
 PollKQueue*
-PollKQueue::create(__UNUSED int maxOpenSockets) {
+PollKQueue::create([[maybe_unused]] int maxOpenSockets) {
   return NULL;
 }
 
 PollKQueue::~PollKQueue() {
 }
 
 int
-PollKQueue::poll(__UNUSED int msec) {
+PollKQueue::poll([[maybe_unused]] int msec) {
   throw internal_error("An PollKQueue function was called, but it is disabled.");
 }
 
@@ -422,57 +422,57 @@ PollKQueue::open_max() const {
 }
 
 void
-PollKQueue::open(__UNUSED torrent::Event* event) {
+PollKQueue::open([[maybe_unused]] torrent::Event* event) {
 }
 
 void
-PollKQueue::close(__UNUSED torrent::Event* event) {
+PollKQueue::close([[maybe_unused]] torrent::Event* event) {
 }
 
 void
-PollKQueue::closed(__UNUSED torrent::Event* event) {
+PollKQueue::closed([[maybe_unused]] torrent::Event* event) {
 }
 
 bool
-PollKQueue::in_read(__UNUSED torrent::Event* event) {
+PollKQueue::in_read([[maybe_unused]] torrent::Event* event) {
   throw internal_error("An PollKQueue function was called, but it is disabled.");
 }
 
 bool
-PollKQueue::in_write(__UNUSED torrent::Event* event) {
+PollKQueue::in_write([[maybe_unused]] torrent::Event* event) {
   throw internal_error("An PollKQueue function was called, but it is disabled.");
 }
 
 bool
-PollKQueue::in_error(__UNUSED torrent::Event* event) {
+PollKQueue::in_error([[maybe_unused]] torrent::Event* event) {
   throw internal_error("An PollKQueue function was called, but it is disabled.");
 }
 
 void
-PollKQueue::insert_read(__UNUSED torrent::Event* event) {
+PollKQueue::insert_read([[maybe_unused]] torrent::Event* event) {
 }
 
 void
-PollKQueue::insert_write(__UNUSED torrent::Event* event) {
+PollKQueue::insert_write([[maybe_unused]] torrent::Event* event) {
 }
 
 void
-PollKQueue::insert_error(__UNUSED torrent::Event* event) {
+PollKQueue::insert_error([[maybe_unused]] torrent::Event* event) {
 }
 
 void
-PollKQueue::remove_read(__UNUSED torrent::Event* event) {
+PollKQueue::remove_read([[maybe_unused]] torrent::Event* event) {
 }
 
 void
-PollKQueue::remove_write(__UNUSED torrent::Event* event) {
+PollKQueue::remove_write([[maybe_unused]] torrent::Event* event) {
 }
 
 void
-PollKQueue::remove_error(__UNUSED torrent::Event* event) {
+PollKQueue::remove_error([[maybe_unused]] torrent::Event* event) {
 }
 
-PollKQueue::PollKQueue(__UNUSED int fd, __UNUSED int maxEvents, __UNUSED int maxOpenSockets) {
+PollKQueue::PollKQueue([[maybe_unused]] int fd, [[maybe_unused]] int maxEvents, [[maybe_unused]] int maxOpenSockets) {
   throw internal_error("An PollKQueue function was called, but it is disabled.");
 }
 

src/torrent/utils/resume.cc

@@ -389,7 +389,7 @@ resume_save_uncertain_pieces(Download download, Object& object) {
 }
 
 bool
-resume_check_target_files(Download download, __UNUSED const Object& object) {
+resume_check_target_files(Download download, [[maybe_unused]] const Object& object) {
   FileList* fileList = download.file_list();
 
   if (!fileList->is_open())
@@ -423,7 +423,7 @@ resume_check_target_files(Download download, __UNUSED const Object& object) {
   } else {
     // We consider empty file lists as being valid.
     return fileList->empty() || fileList->front()->is_created();
-  }    
+  }
 }
 
 void

src/tracker/tracker_udp.cc

@@ -302,7 +302,7 @@ TrackerUdp::event_write() {
   if (m_writeBuffer->size_end() == 0)
     throw internal_error("TrackerUdp::write() called but the write buffer is empty.");
 
-  int __UNUSED s = write_datagram(m_writeBuffer->begin(), m_writeBuffer->size_end(), &m_connectAddress);
+  [[maybe_unused]] int s = write_datagram(m_writeBuffer->begin(), m_writeBuffer->size_end(), &m_connectAddress);
 
   manager->poll()->remove_write(this);
 }

test/configure.ac

@@ -18,11 +18,6 @@ TORRENT_CHECK_CACHELINE()
 TORRENT_MINCORE()
 TORRENT_OTFD()
 
-CC_ATTRIBUTE_UNUSED(
-	AC_DEFINE([__UNUSED], [__attribute__((unused))], [Wrapper around unused attribute]),
-	AC_DEFINE([__UNUSED], [], [Null-wrapper if unused attribute is unsupported])
-)
-
 AC_OUTPUT([
 	Makefile
-])
+])

test/torrent/utils/test_queue_buckets.cc

@@ -44,7 +44,7 @@ static int items_destroyed = 0;
 
 template <>
 void
-test_constants::destroy<int>(__UNUSED int& obj) {
+test_constants::destroy<int>([[maybe_unused]] int& obj) {
   items_destroyed++;
 }