Merge #15894: Remove duplicated "Error: " prefix in logs

f724f31401b963c75bd64f5e2c5b9d9561a9a9dd Make AbortNode() aware of MSG_NOPREFIX flag (Hennadii Stepanov)
96fd4ee02f6c3be21cade729b95a85c60634b0f8 Add MSG_NOPREFIX flag for user messages (Hennadii Stepanov)
f0641f274ffe94fbe7cae43c07a9373013739df2 Prepend the error/warning prefix for GUI messages (Hennadii Stepanov)

Pull request description:

  The "Error" prefix/title is set already in the next functions:
  - `noui_ThreadSafeMessageBox()`https://github.com/bitcoin/bitcoin/blob/2068f089c8b7b90eb4557d3f67ea0f0ed2059a23/src/noui.cpp#L17
  - `ThreadSafeMessageBox()`https://github.com/bitcoin/bitcoin/blob/a720a983015c9ef8cc814c16a5b9ef6379695817/src/qt/bitcoingui.cpp#L1351

  Currently on master:
  ![Screenshot from 2019-04-25 22-08-54](https://user-images.githubusercontent.com/32963518/56763092-25ee8280-67aa-11e9-86c8-6a029dd9ab08.png)

  With this PR:
  ![Screenshot from 2019-04-25 22-26-36](https://user-images.githubusercontent.com/32963518/56763107-30108100-67aa-11e9-9021-683cbd7e2aaa.png)

ACKs for top commit:
  laanwj:
    concept and code-review ACK f724f31401b963c75bd64f5e2c5b9d9561a9a9dd

Tree-SHA512: 218a179b81cc2ac64239d833c02b4c4d4da9b976728a2dcd645966726c4c660b6f1fe43aa28f33d1cb566785a4329e7f93bf5a502bf202316db79d2ff5fce0f8

1 files changed, 16 insertions, 14 deletions

diff --git a/src/qt/bitcoingui.cpp b/src/qt/bitcoingui.cpp
index 8388e8d36e..babb2ce518 100644
--- a/src/qt/bitcoingui.cpp
+++ b/src/qt/bitcoingui.cpp
@@ -1039,49 +1039,51 @@ void BitcoinGUI::setNumBlocks(int count, const QDateTime& blockDate, double nVer
     progressBar->setToolTip(tooltip);
 }
 
-void BitcoinGUI::message(const QString &title, const QString &message, unsigned int style, bool *ret)
+void BitcoinGUI::message(const QString& title, QString message, unsigned int style, bool* ret)
 {
-    QString strTitle = tr("Bitcoin"); // default title
+    // Default title. On macOS, the window title is ignored (as required by the macOS Guidelines).
+    QString strTitle{PACKAGE_NAME};
     // Default to information icon
     int nMBoxIcon = QMessageBox::Information;
     int nNotifyIcon = Notificator::Information;
 
-    QString msgType;
+    bool prefix = !(style & CClientUIInterface::MSG_NOPREFIX);
+    style &= ~CClientUIInterface::MSG_NOPREFIX;
 
-    // Prefer supplied title over style based title
+    QString msgType;
     if (!title.isEmpty()) {
         msgType = title;
-    }
-    else {
+    } else {
         switch (style) {
         case CClientUIInterface::MSG_ERROR:
             msgType = tr("Error");
+            if (prefix) message = tr("Error: %1").arg(message);
             break;
         case CClientUIInterface::MSG_WARNING:
             msgType = tr("Warning");
+            if (prefix) message = tr("Warning: %1").arg(message);
             break;
         case CClientUIInterface::MSG_INFORMATION:
             msgType = tr("Information");
+            // No need to prepend the prefix here.
             break;
         default:
             break;
         }
     }
-    // Append title to "Bitcoin - "
-    if (!msgType.isEmpty())
+
+    if (!msgType.isEmpty()) {
         strTitle += " - " + msgType;
+    }
 
-    // Check for error/warning icon
     if (style & CClientUIInterface::ICON_ERROR) {
         nMBoxIcon = QMessageBox::Critical;
         nNotifyIcon = Notificator::Critical;
-    }
-    else if (style & CClientUIInterface::ICON_WARNING) {
+    } else if (style & CClientUIInterface::ICON_WARNING) {
         nMBoxIcon = QMessageBox::Warning;
         nNotifyIcon = Notificator::Warning;
     }
 
-    // Display message
     if (style & CClientUIInterface::MODAL) {
         // Check for buttons, use OK as default, if none was supplied
         QMessageBox::StandardButton buttons;
@@ -1094,9 +1096,9 @@ void BitcoinGUI::message(const QString &title, const QString &message, unsigned
         int r = mBox.exec();
         if (ret != nullptr)
             *ret = r == QMessageBox::Ok;
-    }
-    else
+    } else {
         notificator->notify(static_cast<Notificator::Class>(nNotifyIcon), strTitle, message);
+    }
 }
 
 void BitcoinGUI::changeEvent(QEvent *e)