gcc: fix various Wnrvo warnings

GCC cannot elide copies with multiple returns.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

taglib/mpeg/id3v2/frames/textidentificationframe.cpp

@@ -449,10 +449,12 @@ UserTextIdentificationFrame *UserTextIdentificationFrame::find(
 
 String UserTextIdentificationFrame::txxxToKey(const String &description)
 {
-  const String d = description.upper();
+  String d = description.upper();
   for(const auto &[o, t] : txxxFrameTranslation) {
-    if(d == o)
-      return t;
+    if(d == o) {
+      d = t;
+      break;
+    }
   }
   return d;
 }

taglib/mpeg/id3v2/id3v2frame.cpp

@@ -286,6 +286,7 @@ void Frame::parse(const ByteVector &data)
 
 ByteVector Frame::fieldData(const ByteVector &frameData) const
 {
+  ByteVector outData;
   unsigned int headerSize = d->header->size();
 
   unsigned int frameDataOffset = headerSize;
@@ -299,10 +300,10 @@ ByteVector Frame::fieldData(const ByteVector &frameData) const
   if(zlib::isAvailable() && d->header->compression() && !d->header->encryption()) {
     if(frameData.size() <= frameDataOffset) {
       debug("Compressed frame doesn't have enough data to decode");
-      return ByteVector();
+      return outData;
     }
 
-    const ByteVector outData = zlib::decompress(frameData.mid(frameDataOffset));
+    outData = zlib::decompress(frameData.mid(frameDataOffset));
     if(!outData.isEmpty() && frameDataLength != outData.size()) {
       debug("frameDataLength does not match the data length returned by zlib");
     }
@@ -310,11 +311,13 @@ ByteVector Frame::fieldData(const ByteVector &frameData) const
     return outData;
   }
 
-  return frameData.mid(frameDataOffset, frameDataLength);
+  outData = frameData.mid(frameDataOffset, frameDataLength);
+  return outData;
 }
 
 String Frame::readStringField(const ByteVector &data, String::Type encoding, int *position)
 {
+  String str;
   int start = 0;
 
   if(!position)
@@ -325,9 +328,8 @@ String Frame::readStringField(const ByteVector &data, String::Type encoding, int
   int end = data.find(delimiter, *position, delimiter.size());
 
   if(end < *position)
-    return String();
+    return str;
 
-  String str;
   if(encoding == String::Latin1)
     str = Tag::latin1StringHandler()->parse(data.mid(*position, end - *position));
   else
@@ -362,13 +364,12 @@ String::Type Frame::checkTextEncoding(const StringList &fields, String::Type enc
 
 PropertyMap Frame::asProperties() const
 {
+  PropertyMap m;
   if(dynamic_cast< const UnknownFrame *>(this)) {
-    PropertyMap m;
     m.addUnsupportedData("UNKNOWN/" + frameID());
     return m;
   }
   const ByteVector &id = frameID();
-  PropertyMap m;
   m.addUnsupportedData(id);
   return m;
 }

taglib/mpeg/id3v2/id3v2synchdata.cpp

@@ -72,14 +72,15 @@ ByteVector SynchData::fromUInt(unsigned int value)
 
 ByteVector SynchData::decode(const ByteVector &data)
 {
+  ByteVector result;
   if(data.isEmpty()) {
-    return ByteVector();
+    return result;
   }
 
   // We have this optimized method instead of using ByteVector::replace(),
   // since it makes a great difference when decoding huge unsynchronized frames.
 
-  ByteVector result(data.size());
+  result = ByteVector(data.size());
 
   auto src = data.begin();
   auto dst = result.begin();

taglib/ogg/oggfile.cpp

@@ -67,18 +67,21 @@ Ogg::File::~File() = default;
 
 ByteVector Ogg::File::packet(unsigned int i)
 {
+  ByteVector packet;
   // Check to see if we're called setPacket() for this packet since the last
   // save:
 
-  if(d->dirtyPackets.contains(i))
-    return d->dirtyPackets[i];
+  if(d->dirtyPackets.contains(i)) {
+    packet = d->dirtyPackets[i];
+    return packet;
+  }
 
   // If we haven't indexed the page where the packet we're interested in starts,
   // begin reading pages until we have.
 
   if(!readPages(i)) {
     debug("Ogg::File::packet() -- Could not find the requested packet.");
-    return ByteVector();
+    return packet;
   }
 
   // Look for the first page in which the requested packet starts.
@@ -94,7 +97,7 @@ ByteVector Ogg::File::packet(unsigned int i)
   // the pages' packet data until we hit a page that either does not end with the
   // packet that we're fetching or where the last packet is complete.
 
-  ByteVector packet = (*it)->packets()[i - (*it)->firstPacketIndex()];
+  packet = (*it)->packets()[i - (*it)->firstPacketIndex()];
 
   while(nextPacketIndex(*it) <= i) {
     ++it;

taglib/ogg/oggpage.cpp

@@ -203,11 +203,13 @@ unsigned int Ogg::Page::packetCount() const
 
 ByteVectorList Ogg::Page::packets() const
 {
-  if(!d->packets.isEmpty())
-    return d->packets;
-
   ByteVectorList l;
 
+  if(!d->packets.isEmpty()) {
+    l = d->packets;
+    return l;
+  }
+
   if(d->file && d->header.isValid()) {
 
     d->file->seek(d->fileOffset + d->header.size());

taglib/tagutils.cpp

@@ -92,8 +92,9 @@ offset_t Utils::findAPE(File *file, offset_t id3v1Location)
 ByteVector TagLib::Utils::readHeader(IOStream *stream, unsigned int length,
                                      bool skipID3v2, offset_t *headerOffset)
 {
+  ByteVector header;
   if(!stream || !stream->isOpen())
-    return ByteVector();
+    return header;
 
   const offset_t originalPosition = stream->tell();
   offset_t bufferOffset = 0;
@@ -106,7 +107,7 @@ ByteVector TagLib::Utils::readHeader(IOStream *stream, unsigned int length,
   }
 
   stream->seek(bufferOffset);
-  const ByteVector header = stream->readBlock(length);
+  header = stream->readBlock(length);
   stream->seek(originalPosition);
 
   if(headerOffset)

taglib/toolkit/tbytevectorstream.cpp

@@ -61,10 +61,11 @@ FileName ByteVectorStream::name() const
 
 ByteVector ByteVectorStream::readBlock(size_t length)
 {
+  ByteVector v;
   if(length == 0)
-    return ByteVector();
+    return v;
 
-  ByteVector v = d->data.mid(static_cast<unsigned int>(d->position),
+  v = d->data.mid(static_cast<unsigned int>(d->position),
                              static_cast<unsigned int>(length));
   d->position += v.size();
   return v;

taglib/toolkit/tfilestream.cpp

@@ -208,13 +208,14 @@ FileName FileStream::name() const
 
 ByteVector FileStream::readBlock(size_t length)
 {
+  ByteVector buffer;
   if(!isOpen()) {
     debug("FileStream::readBlock() -- invalid file.");
-    return ByteVector();
+    return buffer;
   }
 
   if(length == 0)
-    return ByteVector();
+    return buffer;
 
   if(length > bufferSize()) {
     if(const auto streamLength = static_cast<size_t>(FileStream::length());
@@ -223,7 +224,7 @@ ByteVector FileStream::readBlock(size_t length)
     }
   }
 
-  ByteVector buffer(static_cast<unsigned int>(length));
+  buffer = ByteVector(static_cast<unsigned int>(length));
 
   const size_t count = readFile(d->file, buffer);
   buffer.resize(static_cast<unsigned int>(count));