Merge #17031: gui: Prevent processing duplicate payment requests

3f89e1e Prevent processing duplicate payment requests (João Barbosa)

Pull request description:

  Considering the following from Qt [src/plugins/platforms/cocoa/qcocoaapplicationdelegate.mm#L267](https://github.com/qt/qtbase/blob/13e0a36626bd75e631dd9536e795a494432b1945/src/plugins/platforms/cocoa/qcocoaapplicationdelegate.mm#L267)

  ```cpp
  - (void)application:(NSApplication *)sender openFiles:(NSArray *)filenames
  {
      Q_UNUSED(filenames);
      Q_UNUSED(sender);

      for (NSString *fileName in filenames) {
          QString qtFileName = QString::fromNSString(fileName);
          if (inLaunch) {
              // We need to be careful because Cocoa will be nice enough to take
              // command line arguments and send them to us as events. Given the history
              // of Qt Applications, this will result in behavior people don't want, as
              // they might be doing the opening themselves with the command line parsing.
              if (qApp->arguments().contains(qtFileName))
                  continue;
          }
          QWindowSystemInterface::handleFileOpenEvent(qtFileName);
      }
  ```

  And that a2714a5 was merged, now Qt isn't able to filter out the above notifications, and then a [QFileOpenEvent](https://doc.qt.io/qt-5/qfileopenevent.html) event is delivered to `PaymentServer::eventFilter`, which in turn (re)adds the payment request.

  This change fixes #17025, but makes sense regardless of the issue.

ACKs for top commit:
  laanwj:
    Nah, this seems fine, utACK 3f89e1e
  Sjors:
    ACK 3f89e1e on macOS 10.14.6
  achow101:
    Code review ACK 3f89e1e

Tree-SHA512: dd1e0c73fd84953418173ca71f6f5a67ad74a5dc7e3b1d54915ef0545f513df6a24f27242a77bb094e2833a478e2f3bf30ecd50251f3c55b65e780097cb8ab4d

Author: fanquake

src/qt/paymentserver.cpp

@@ -82,7 +82,7 @@ static QString ipcServerName()
 // the main GUI window is up and ready to ask the user
 // to send payment.
 
-static QList<QString> savedPaymentRequests;
+static QSet<QString> savedPaymentRequests;
 
 //
 // Sending to the server is done synchronously, at startup.
@@ -107,7 +107,8 @@ void PaymentServer::ipcParseCommandLine(interfaces::Node& node, int argc, char*
         // will start a mainnet instance and throw a "wrong network" error.
         if (arg.startsWith(BITCOIN_IPC_PREFIX, Qt::CaseInsensitive)) // bitcoin: URI
         {
-            savedPaymentRequests.append(arg);
+            if (savedPaymentRequests.contains(arg)) continue;
+            savedPaymentRequests.insert(arg);
 
             SendCoinsRecipient r;
             if (GUIUtil::parseBitcoinURI(arg, &r) && !r.address.isEmpty())
@@ -127,7 +128,8 @@ void PaymentServer::ipcParseCommandLine(interfaces::Node& node, int argc, char*
 #ifdef ENABLE_BIP70
         else if (QFile::exists(arg)) // Filename
         {
-            savedPaymentRequests.append(arg);
+            if (savedPaymentRequests.contains(arg)) continue;
+            savedPaymentRequests.insert(arg);
 
             PaymentRequestPlus request;
             if (readPaymentRequestFromFile(arg, request))
@@ -280,7 +282,7 @@ void PaymentServer::handleURIOrFile(const QString& s)
 {
     if (saveURIs)
     {
-        savedPaymentRequests.append(s);
+        savedPaymentRequests.insert(s);
         return;
     }