refactor: remove unused vars, code simplify and minor optimize (#4172)

libtransmission/bandwidth.cc

@@ -144,10 +144,11 @@ void tr_bandwidth::allocateBandwidth(
     tr_priority_t const priority = std::max(parent_priority, this->priority_);
 
     /* set the available bandwidth */
-    if (this->band_[dir].is_limited_)
+    auto bandwidth = &this->band_[dir];
+    if (bandwidth->is_limited_)
     {
-        uint64_t const next_pulse_speed = this->band_[dir].desired_speed_bps_;
-        this->band_[dir].bytes_left_ = next_pulse_speed * period_msec / 1000U;
+        uint64_t const next_pulse_speed = bandwidth->desired_speed_bps_;
+        bandwidth->bytes_left_ = next_pulse_speed * period_msec / 1000U;
     }
 
     /* add this bandwidth's peer, if any, to the peer pool */

libtransmission/watchdir.cc

@@ -111,8 +111,6 @@ void BaseWatchdir::processFile(std::string_view basename)
 
 void BaseWatchdir::scan()
 {
-    auto new_dir_entries = std::set<std::string>{};
-
     tr_error* error = nullptr;
     auto const dir = tr_sys_dir_open(dirname_.c_str(), &error);
     if (dir == TR_BAD_SYS_DIR)

qt/IconCache.cc

@@ -65,7 +65,7 @@ QIcon IconCache::guessMimeIcon(QString const& filename, QIcon fallback) const
 
     if (icon.isNull())
     {
-        icon = fallback;
+        icon = std::move(fallback);
     }
 
     return icon;

qt/Prefs.cc

@@ -197,7 +197,6 @@ bool isValidUtf8(QByteArray const& byteArray)
 
     auto const* const codec = QTextCodec::codecForName("UTF-8");
     auto state = QTextCodec::ConverterState{};
-    auto const text = codec->toUnicode(byteArray.constData(), byteArray.size(), &state);
     return state.invalidChars == 0;
 
 #endif

qt/StyleHelper.cc

@@ -5,7 +5,7 @@
 
 #include "StyleHelper.h"
 
-QIcon::Mode StyleHelper::getIconMode(QStyle::State state)
+QIcon::Mode StyleHelper::getIconMode(QStyle::State const& state)
 {
     if (!state.testFlag(QStyle::State_Enabled))
     {

qt/StyleHelper.h

@@ -11,5 +11,5 @@
 class StyleHelper
 {
 public:
-    static QIcon::Mode getIconMode(QStyle::State state);
+    static QIcon::Mode getIconMode(QStyle::State const& state);
 };

qt/Torrent.h

@@ -112,9 +112,7 @@ private:
     tr_sha1_digest_t data_ = {};
 
 public:
-    TorrentHash()
-    {
-    }
+    TorrentHash() = default;
 
     explicit TorrentHash(tr_sha1_digest_t const& data)
         : data_{ data }

tests/libtransmission/magnet-metainfo-test.cc

@@ -93,8 +93,6 @@ TEST(MagnetMetainfo, magnetParse)
 
 TEST(WebUtilsTest, parseMagnetFuzzRegressions)
 {
-    auto buf = std::vector<char>{};
-
     static auto constexpr Tests = std::array<std::string_view, 1>{
         "UICOl7RLjChs/QZZwNH4sSQwuH890UMHuoxoWBmMkr0=",
     };