refactor: unify container presence checks - non-trivial counts

The changes made here were:

| From              | To               |
|-------------------|------------------|
| `m.count(k) == 1` | `m.contains(k)`  |
| `m.count(k) == 0` | `!m.contains(k)` |
| `m.count(k) != 1` | `!m.contains(k)` |
| `m.count(k) < 1`  | `!m.contains(k)` |

* `mapInfo` is instance of `std::unordered_map` and can only contain 0 or 1 value for a given key;
* similarly, `g_enabled_filter_types` and `setClientRules` are both `std::set` instances;
* lastly, while `mapTxSpends` is `std::unordered_multimap` that could potentially hold multiple values, having a size less than 1 means that the value is missing.

`QMap<WalletModel*, WalletView*> mapWalletViews` values were also migrated manually.

Co-authored-by: pablomartin4btc <pablomartin4btc@gmail.com>
Co-authored-by: fanquake <fanquake@gmail.com>

src/addrman.cpp

@@ -516,7 +516,7 @@ void AddrManImpl::MakeTried(AddrInfo& info, nid_type nId)
     if (vvTried[nKBucket][nKBucketPos] != -1) {
         // find an item to evict
         nid_type nIdEvict = vvTried[nKBucket][nKBucketPos];
-        assert(mapInfo.count(nIdEvict) == 1);
+        assert(mapInfo.contains(nIdEvict));
         AddrInfo& infoOld = mapInfo[nIdEvict];
 
         // Remove the to-be-evicted item from the tried set.
@@ -919,7 +919,7 @@ void AddrManImpl::ResolveCollisions_()
         bool erase_collision = false;
 
         // If id_new not found in mapInfo remove it from m_tried_collisions
-        if (mapInfo.count(id_new) != 1) {
+        if (!mapInfo.contains(id_new)) {
             erase_collision = true;
         } else {
             AddrInfo& info_new = mapInfo[id_new];
@@ -985,7 +985,7 @@ std::pair<CAddress, NodeSeconds> AddrManImpl::SelectTriedCollision_()
     nid_type id_new = *it;
 
     // If id_new not found in mapInfo remove it from m_tried_collisions
-    if (mapInfo.count(id_new) != 1) {
+    if (!mapInfo.contains(id_new)) {
         m_tried_collisions.erase(it);
         return {};
     }

src/init.cpp

@@ -968,7 +968,7 @@ bool AppInitParameterInteraction(const ArgsManager& args)
 
     // Signal NODE_COMPACT_FILTERS if peerblockfilters and basic filters index are both enabled.
     if (args.GetBoolArg("-peerblockfilters", DEFAULT_PEERBLOCKFILTERS)) {
-        if (g_enabled_filter_types.count(BlockFilterType::BASIC) != 1) {
+        if (!g_enabled_filter_types.contains(BlockFilterType::BASIC)) {
             return InitError(_("Cannot set -peerblockfilters without -blockfilterindex."));
         }
 

src/qt/walletframe.cpp

@@ -70,7 +70,7 @@ bool WalletFrame::addView(WalletView* walletView)
 {
     if (!clientModel) return false;
 
-    if (mapWalletViews.count(walletView->getWalletModel()) > 0) return false;
+    if (mapWalletViews.contains(walletView->getWalletModel())) return false;
 
     walletView->setClientModel(clientModel);
     walletView->showOutOfSyncWarning(bOutOfSync);
@@ -90,7 +90,7 @@ bool WalletFrame::addView(WalletView* walletView)
 
 void WalletFrame::setCurrentWallet(WalletModel* wallet_model)
 {
-    if (mapWalletViews.count(wallet_model) == 0) return;
+    if (!mapWalletViews.contains(wallet_model)) return;
 
     // Stop the effect of hidden widgets on the size hint of the shown one in QStackedWidget.
     WalletView* view_about_to_hide = currentWalletView();
@@ -116,7 +116,7 @@ void WalletFrame::setCurrentWallet(WalletModel* wallet_model)
 
 void WalletFrame::removeWallet(WalletModel* wallet_model)
 {
-    if (mapWalletViews.count(wallet_model) == 0) return;
+    if (!mapWalletViews.contains(wallet_model)) return;
 
     WalletView *walletView = mapWalletViews.take(wallet_model);
     walletStack->removeWidget(walletView);

src/txrequest.cpp

@@ -580,7 +580,7 @@ public:
         // Bail out if we already have a CANDIDATE_BEST announcement for this (txhash, peer) combination. The case
         // where there is a non-CANDIDATE_BEST announcement already will be caught by the uniqueness property of the
         // ByPeer index when we try to emplace the new object below.
-        if (m_index.get<ByPeer>().count(ByPeerView{peer, true, gtxid.ToUint256()})) return;
+        if (m_index.get<ByPeer>().contains(ByPeerView{peer, true, gtxid.ToUint256()})) return;
 
         // Try creating the announcement with CANDIDATE_DELAYED state (which will fail due to the uniqueness
         // of the ByPeer index if a non-CANDIDATE_BEST announcement already exists with the same txhash and peer).

src/wallet/wallet.cpp

@@ -265,7 +265,7 @@ void WaitForDeleteWallet(std::shared_ptr<CWallet>&& wallet)
     wallet.reset();
     {
         WAIT_LOCK(g_wallet_release_mutex, lock);
-        while (g_unloading_wallet_set.count(name) == 1) {
+        while (g_unloading_wallet_set.contains(name)) {
             g_wallet_release_cv.wait(lock);
         }
     }
@@ -1525,7 +1525,7 @@ void CWallet::blockDisconnected(const interfaces::BlockInfo& block)
 
         for (const CTxIn& tx_in : ptx->vin) {
             // No other wallet transactions conflicted with this transaction
-            if (mapTxSpends.count(tx_in.prevout) < 1) continue;
+            if (!mapTxSpends.contains(tx_in.prevout)) continue;
 
             std::pair<TxSpends::const_iterator, TxSpends::const_iterator> range = mapTxSpends.equal_range(tx_in.prevout);