Use CoinControl to pass custom fee setting from QT.

This fixes buggy behavior where we were temporarily setting and unsetting the
global payTxFee when trying to send a transaction with a custom fee from the
GUI. The previous behavior was inconsistent depending on the order of using the
RPC call settxfee and clicking various radio buttons in the sendcoinsdialog.
The new behavior is that transactions sent with the GUI will always use either
the smartfee slider value or the custom fee set on the GUI and they will not
affect the global defaults which are only for RPC and initial GUI values.

src/qt/sendcoinsdialog.cpp

@@ -175,18 +175,13 @@ void SendCoinsDialog::setModel(WalletModel *_model)
             ui->confTargetSelector->addItem(tr("%1 (%2 blocks)").arg(GUIUtil::formatNiceTimeOffset(n*Params().GetConsensus().nPowTargetSpacing)).arg(n));
         }
         connect(ui->confTargetSelector, SIGNAL(currentIndexChanged(int)), this, SLOT(updateSmartFeeLabel()));
-        connect(ui->confTargetSelector, SIGNAL(currentIndexChanged(int)), this, SLOT(updateGlobalFeeVariables()));
         connect(ui->confTargetSelector, SIGNAL(currentIndexChanged(int)), this, SLOT(coinControlUpdateLabels()));
         connect(ui->groupFee, SIGNAL(buttonClicked(int)), this, SLOT(updateFeeSectionControls()));
-        connect(ui->groupFee, SIGNAL(buttonClicked(int)), this, SLOT(updateGlobalFeeVariables()));
         connect(ui->groupFee, SIGNAL(buttonClicked(int)), this, SLOT(coinControlUpdateLabels()));
-        connect(ui->groupCustomFee, SIGNAL(buttonClicked(int)), this, SLOT(updateGlobalFeeVariables()));
         connect(ui->groupCustomFee, SIGNAL(buttonClicked(int)), this, SLOT(coinControlUpdateLabels()));
-        connect(ui->customFee, SIGNAL(valueChanged()), this, SLOT(updateGlobalFeeVariables()));
         connect(ui->customFee, SIGNAL(valueChanged()), this, SLOT(coinControlUpdateLabels()));
         connect(ui->checkBoxMinimumFee, SIGNAL(stateChanged(int)), this, SLOT(setMinimumFee()));
         connect(ui->checkBoxMinimumFee, SIGNAL(stateChanged(int)), this, SLOT(updateFeeSectionControls()));
-        connect(ui->checkBoxMinimumFee, SIGNAL(stateChanged(int)), this, SLOT(updateGlobalFeeVariables()));
         connect(ui->checkBoxMinimumFee, SIGNAL(stateChanged(int)), this, SLOT(coinControlUpdateLabels()));
         connect(ui->optInRBF, SIGNAL(stateChanged(int)), this, SLOT(updateSmartFeeLabel()));
         connect(ui->optInRBF, SIGNAL(stateChanged(int)), this, SLOT(coinControlUpdateLabels()));
@@ -194,7 +189,6 @@ void SendCoinsDialog::setModel(WalletModel *_model)
         updateFeeSectionControls();
         updateMinFeeLabel();
         updateSmartFeeLabel();
-        updateGlobalFeeVariables();
 
         // set default rbf checkbox state
         ui->optInRBF->setCheckState(model->getDefaultWalletRbf() ? Qt::Checked : Qt::Unchecked);
@@ -274,12 +268,8 @@ void SendCoinsDialog::on_sendButton_clicked()
     CCoinControl ctrl;
     if (model->getOptionsModel()->getCoinControlFeatures())
         ctrl = *CoinControlDialog::coinControl;
-    if (ui->radioSmartFee->isChecked()) {
-        ctrl.m_confirm_target = getConfTargetForIndex(ui->confTargetSelector->currentIndex());
-    } else {
-        ctrl.m_confirm_target = boost::none;
-    }
-    ctrl.signalRbf = ui->optInRBF->isChecked();
+
+    updateCoinControlState(ctrl);
 
     prepareStatus = model->prepareTransaction(currentTransaction, ctrl);
 
@@ -636,18 +626,6 @@ void SendCoinsDialog::updateFeeSectionControls()
     ui->customFee               ->setEnabled(ui->radioCustomFee->isChecked() && !ui->checkBoxMinimumFee->isChecked());
 }
 
-void SendCoinsDialog::updateGlobalFeeVariables()
-{
-    if (ui->radioSmartFee->isChecked())
-    {
-        payTxFee = CFeeRate(0);
-    }
-    else
-    {
-        payTxFee = CFeeRate(ui->customFee->value());
-    }
-}
-
 void SendCoinsDialog::updateFeeMinimizedLabel()
 {
     if(!model || !model->getOptionsModel())
@@ -669,15 +647,30 @@ void SendCoinsDialog::updateMinFeeLabel()
         );
 }
 
+void SendCoinsDialog::updateCoinControlState(CCoinControl& ctrl)
+{
+    if (ui->radioCustomFee->isChecked()) {
+        ctrl.m_feerate = CFeeRate(ui->customFee->value());
+    } else {
+        ctrl.m_feerate = boost::none;
+    }
+    // Avoid using global defaults when sending money from the GUI
+    // Either custom fee will be used or if not selected, the confirmation target from dropdown box
+    ctrl.m_confirm_target = getConfTargetForIndex(ui->confTargetSelector->currentIndex());
+    ctrl.signalRbf = ui->optInRBF->isChecked();
+}
+
 void SendCoinsDialog::updateSmartFeeLabel()
 {
     if(!model || !model->getOptionsModel())
         return;
-
-    int nBlocksToConfirm = getConfTargetForIndex(ui->confTargetSelector->currentIndex());
+    CCoinControl coin_control;
+    updateCoinControlState(coin_control);
+    coin_control.m_feerate = boost::none; // Explicitly use only fee estimation rate for smart fee labels
     FeeCalculation feeCalc;
-    bool conservative_estimate = CalculateEstimateType(FeeEstimateMode::UNSET, ui->optInRBF->isChecked());
-    CFeeRate feeRate = ::feeEstimator.estimateSmartFee(nBlocksToConfirm, &feeCalc, ::mempool, conservative_estimate);
+    bool conservative_estimate = CalculateEstimateType(FeeEstimateMode::UNSET, coin_control.signalRbf);
+    CFeeRate feeRate = ::feeEstimator.estimateSmartFee(*coin_control.m_confirm_target, &feeCalc, ::mempool, conservative_estimate);
+
     if (feeRate <= CFeeRate(0)) // not enough data => minfee
     {
         ui->labelSmartFee->setText(BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(),
@@ -752,8 +745,6 @@ void SendCoinsDialog::coinControlFeatureChanged(bool checked)
     if (!checked && model) // coin control features disabled
         CoinControlDialog::coinControl->SetNull();
 
-    // make sure we set back the confirmation target
-    updateGlobalFeeVariables();
     coinControlUpdateLabels();
 }
 
@@ -844,15 +835,11 @@ void SendCoinsDialog::coinControlUpdateLabels()
     if (!model || !model->getOptionsModel())
         return;
 
+    updateCoinControlState(*CoinControlDialog::coinControl);
+
     // set pay amounts
     CoinControlDialog::payAmounts.clear();
     CoinControlDialog::fSubtractFeeFromAmount = false;
-    if (ui->radioSmartFee->isChecked()) {
-        CoinControlDialog::coinControl->m_confirm_target = getConfTargetForIndex(ui->confTargetSelector->currentIndex());
-    } else {
-        CoinControlDialog::coinControl->m_confirm_target = boost::none;
-    }
-    CoinControlDialog::coinControl->signalRbf = ui->optInRBF->isChecked();
 
     for(int i = 0; i < ui->entries->count(); ++i)
     {

src/qt/sendcoinsdialog.h

@@ -68,6 +68,8 @@ private:
     void processSendCoinsReturn(const WalletModel::SendCoinsReturn &sendCoinsReturn, const QString &msgArg = QString());
     void minimizeFeeSection(bool fMinimize);
     void updateFeeMinimizedLabel();
+    // Update the passed in CCoinControl with state from the GUI
+    void updateCoinControlState(CCoinControl& ctrl);
 
 private Q_SLOTS:
     void on_sendButton_clicked();
@@ -91,7 +93,6 @@ private Q_SLOTS:
     void updateFeeSectionControls();
     void updateMinFeeLabel();
     void updateSmartFeeLabel();
-    void updateGlobalFeeVariables();
 
 Q_SIGNALS:
     // Fired when a message should be reported to the user