Qt/Intro: Allow changing prune setting even when specified on commandline

src/qt/intro.cpp

@@ -154,7 +154,6 @@ Intro::Intro(QWidget *parent, int64_t blockchain_size_gb, int64_t chain_state_si
         default:
             ui->prune->setChecked(true);
         }
-        ui->prune->setEnabled(false);
     }
     ui->pruneMiB->setValue(m_prune_target_mib);
     ui->pruneMiB->setToolTip(ui->prune->toolTip());

src/qt/optionsmodel.cpp

@@ -238,6 +238,9 @@ bool OptionsModel::Init(bilingual_str& error)
     // and we want command-line parameters to overwrite the GUI settings.
     for (OptionID option : {DatabaseCache, ThreadsScriptVerif, SpendZeroConfChange, ExternalSignerPath, MapPortUPnP,
                             MapPortNatpmp, Listen, Server, PruneTristate, ProxyUse, ProxyUseTor, Language}) {
+        // isSettingIgnored will have a false positive here during first-run prune changes
+        if (option == PruneTristate && m_prune_forced_by_gui) continue;
+
         std::string setting = SettingName(option);
         if (node().isSettingIgnored(setting)) addOverriddenOption("-" + setting);
         try {
@@ -397,6 +400,7 @@ void OptionsModel::SetPruneTargetMiB(int prune_target_mib)
     // this point because this function is only called after the intro screen is
     // shown, before the node starts.
     node().forceSetting("prune", new_value);
+    m_prune_forced_by_gui = true;
 
     // Update settings.json if value configured in intro screen is different
     // from saved value. Avoid writing settings.json if bitcoin.conf value

src/qt/optionsmodel.h

@@ -138,6 +138,7 @@ private:
 
     /* settings that were overridden by command-line */
     QString strOverriddenByCommandLine;
+    bool m_prune_forced_by_gui{false};
 
     static QString FontChoiceToString(const OptionsModel::FontChoice&);
     static FontChoice FontChoiceFromString(const QString&);