Migrate away from deprecated QVariant comparison operators

Another idea would be manually define a custom comparison function for
QVariant. However, having the function would be excessive due to its
limited usage count, also note that we are already casting
various QVariant to its underlying type in existing code.

src/gui/transferlistsortmodel.cpp

@@ -41,7 +41,6 @@ TransferListSortModel::TransferListSortModel(QObject *parent)
     : QSortFilterProxyModel {parent}
 {
     setSortRole(TransferListModel::UnderlyingDataRole);
-    QMetaType::registerComparators<BitTorrent::TorrentState>();
 }
 
 void TransferListSortModel::setStatusFilter(TorrentFilter::Type filter)
@@ -122,21 +121,21 @@ bool TransferListSortModel::lessThan_impl(const QModelIndex &left, const QModelI
         return (Utils::String::naturalCompare(leftValue.toString(), rightValue.toString(), Qt::CaseInsensitive) < 0);
 
     case TransferListModel::TR_STATUS:
-        // QSortFilterProxyModel::lessThan() uses the < operator only for specific QVariant types
-        // so our custom type is outside that list.
-        // In this case QSortFilterProxyModel::lessThan() converts other types to QString and
-        // sorts them.
-        // Thus we can't use the code in the default label.
-        if (leftValue != rightValue)
-            return leftValue < rightValue;
-        return invokeLessThanForColumn(TransferListModel::TR_QUEUE_POSITION);
+        {
+            const auto stateL = leftValue.value<BitTorrent::TorrentState>();
+            const auto stateR = rightValue.value<BitTorrent::TorrentState>();
+
+            if (stateL != stateR)
+                return stateL < stateR;
+            return invokeLessThanForColumn(TransferListModel::TR_QUEUE_POSITION);
+        }
 
     case TransferListModel::TR_ADD_DATE:
     case TransferListModel::TR_SEED_DATE:
     case TransferListModel::TR_SEEN_COMPLETE_DATE:
-    {
-            const QDateTime dateL = leftValue.toDateTime();
-            const QDateTime dateR = rightValue.toDateTime();
+        {
+            const auto dateL = leftValue.toDateTime();
+            const auto dateR = rightValue.toDateTime();
 
             if (dateL.isValid() && dateR.isValid())
             {
@@ -156,20 +155,21 @@ bool TransferListSortModel::lessThan_impl(const QModelIndex &left, const QModelI
         }
 
     case TransferListModel::TR_QUEUE_POSITION:
-    {
-            // QVariant has comparators for all basic types
-            if ((leftValue > 0) || (rightValue > 0))
-            {
-                if ((leftValue > 0) && (rightValue > 0))
-                    return leftValue < rightValue;
+        {
+            const auto positionL = leftValue.toInt();
+            const auto positionR = rightValue.toInt();
 
-                return leftValue != 0;
+            if ((positionL > 0) || (positionR > 0))
+            {
+                if ((positionL > 0) && (positionR > 0))
+                    return positionL < positionR;
+                return positionL != 0;
             }
 
             // Sort according to TR_SEED_DATE
-            const QDateTime dateL = left.sibling(left.row(), TransferListModel::TR_SEED_DATE)
+            const auto dateL = left.sibling(left.row(), TransferListModel::TR_SEED_DATE)
                     .data(TransferListModel::UnderlyingDataRole).toDateTime();
-            const QDateTime dateR = right.sibling(right.row(), TransferListModel::TR_SEED_DATE)
+            const auto dateR = right.sibling(right.row(), TransferListModel::TR_SEED_DATE)
                     .data(TransferListModel::UnderlyingDataRole).toDateTime();
 
             if (dateL.isValid() && dateR.isValid())
@@ -191,22 +191,23 @@ bool TransferListSortModel::lessThan_impl(const QModelIndex &left, const QModelI
 
     case TransferListModel::TR_SEEDS:
     case TransferListModel::TR_PEERS:
-    {
-            // QVariant has comparators for all basic types
-            // Active peers/seeds take precedence over total peers/seeds.
-            if (leftValue != rightValue)
-                return (leftValue < rightValue);
-
-            const QVariant leftValueTotal = left.data(TransferListModel::AdditionalUnderlyingDataRole);
-            const QVariant rightValueTotal = right.data(TransferListModel::AdditionalUnderlyingDataRole);
-            if (leftValueTotal != rightValueTotal)
-                return (leftValueTotal < rightValueTotal);
+        {
+            // Active peers/seeds take precedence over total peers/seeds
+            const auto activeL = leftValue.toInt();
+            const auto activeR = rightValue.toInt();
+            if (activeL != activeR)
+                return activeL < activeR;
+
+            const auto totalL = left.data(TransferListModel::AdditionalUnderlyingDataRole).toInt();
+            const auto totalR = right.data(TransferListModel::AdditionalUnderlyingDataRole).toInt();
+            if (totalL != totalR)
+                return totalL < totalR;
 
             return invokeLessThanForColumn(TransferListModel::TR_QUEUE_POSITION);
         }
 
     case TransferListModel::TR_ETA:
-    {
+        {
             // Sorting rules prioritized.
             // 1. Active torrents at the top
             // 2. Seeding torrents at the bottom
@@ -221,9 +222,9 @@ bool TransferListSortModel::lessThan_impl(const QModelIndex &left, const QModelI
             if (isActiveL != isActiveR)
                 return isActiveL;
 
-            const int queuePosL = left.sibling(left.row(), TransferListModel::TR_QUEUE_POSITION)
+            const auto queuePosL = left.sibling(left.row(), TransferListModel::TR_QUEUE_POSITION)
                     .data(TransferListModel::UnderlyingDataRole).toInt();
-            const int queuePosR = right.sibling(right.row(), TransferListModel::TR_QUEUE_POSITION)
+            const auto queuePosR = right.sibling(right.row(), TransferListModel::TR_QUEUE_POSITION)
                     .data(TransferListModel::UnderlyingDataRole).toInt();
             const bool isSeedingL = (queuePosL < 0);
             const bool isSeedingR = (queuePosR < 0);
@@ -236,8 +237,8 @@ bool TransferListSortModel::lessThan_impl(const QModelIndex &left, const QModelI
                 return isAscendingOrder;
             }
 
-            const qlonglong etaL = leftValue.toLongLong();
-            const qlonglong etaR = rightValue.toLongLong();
+            const auto etaL = leftValue.toLongLong();
+            const auto etaR = rightValue.toLongLong();
             const bool isInvalidL = ((etaL < 0) || (etaL >= MAX_ETA));
             const bool isInvalidR = ((etaR < 0) || (etaR >= MAX_ETA));
             if (isInvalidL && isInvalidR)
@@ -255,12 +256,24 @@ bool TransferListSortModel::lessThan_impl(const QModelIndex &left, const QModelI
         }
 
     case TransferListModel::TR_LAST_ACTIVITY:
+        {
+            const auto lastActivityL = leftValue.toLongLong();
+            const auto lastActivityR = rightValue.toLongLong();
+
+            if (lastActivityL < 0) return false;
+            if (lastActivityR < 0) return true;
+            return lastActivityL < lastActivityR;
+        }
+
     case TransferListModel::TR_RATIO_LIMIT:
-        // QVariant has comparators for all basic types
-        if (leftValue < 0) return false;
-        if (rightValue < 0) return true;
+        {
+            const auto ratioL = leftValue.toReal();
+            const auto ratioR = rightValue.toReal();
 
-        return (leftValue < rightValue);
+            if (ratioL < 0) return false;
+            if (ratioR < 0) return true;
+            return ratioL < ratioR;
+        }
     }
 
     return (leftValue != rightValue)