Merge bitcoin-core/gui#556: refactor: Make BitcoinUnits::Unit a scoped enum

0e5dedbc9eb54105ab9b0c4ce1f57afa55bcb5b6 qt/wallettests: sort includes (William Casarin)
0554251d660caa1c3f5f44ae1d9fa3c23d2aac18 qt: Skip displayUnitChanged signal if unit is not actually changed (Hennadii Stepanov)
ffbc2fe459034024cb2fce9fd94bff457b7a7d49 qt, refactor: Remove default cases for scoped enum (Hennadii Stepanov)
152d5bad50f145af922011f6ec1fd9afd9076ceb qt, refactor: Remove BitcoinUnits::valid function (Hennadii Stepanov)
aa23960fdf1deff321ecea435026c87db78498fb qt, refactor: Make BitcoinUnits::Unit a scoped enum (Hennadii Stepanov)
75832fdc37ea3fe9cf515bd1946e220fe07a440b qt: Use QVariant instead of int for BitcoinUnit in QSettings (Hennadii Stepanov)

Pull request description:

  This is a rebased version of #60

  Since Qt 5.5 there are [means](https://doc.qt.io/qt-5/qobject.html#Q_ENUM) to register an enum type with the meta-object system (such enum still lacks an ability to interact with [QSettings::setValue()](https://doc.qt.io/qt-5/qsettings.html#setValue) and [QSettings::value()](https://doc.qt.io/qt-5/qsettings.html#value) without defined stream operators).

  In order to reduce global namespace polluting and to force strong type checking, this PR makes BitcoinUnits::Unit a scoped enum (typedef BitcoinUnits::Unit BitcoinUnit;).

  No behavior change.

ACKs for top commit:
  jonatack:
    ACK 0e5dedbc9eb54105ab9b0c4ce1f57afa55bcb5b6, review and debug build of each commit after rebase on current master, lightly tested running the GUI, changing units a few times, and verifying persistence after restarting
  promag:
    Code review ACK 0e5dedbc9eb54105ab9b0c4ce1f57afa55bcb5b6

Tree-SHA512: 39ec0d7e4f0b9b25be287888121a8db6b282339674e37ec3a3554da63a9e22d6fe079e8310ca289b2a0356a19b3c7e55afa17d09dd34e0f222177f603bb053a3

1 files changed, 18 insertions, 13 deletions

diff --git a/src/qt/optionsmodel.cpp b/src/qt/optionsmodel.cpp
index 52bda59748..40b9ed5483 100644
--- a/src/qt/optionsmodel.cpp
+++ b/src/qt/optionsmodel.cpp
@@ -24,6 +24,7 @@
 #include <QLatin1Char>
 #include <QSettings>
 #include <QStringList>
+#include <QVariant>
 
 const char *DEFAULT_GUI_PROXY_HOST = "127.0.0.1";
 
@@ -71,9 +72,16 @@ void OptionsModel::Init(bool resetSettings)
     fMinimizeOnClose = settings.value("fMinimizeOnClose").toBool();
 
     // Display
-    if (!settings.contains("nDisplayUnit"))
-        settings.setValue("nDisplayUnit", BitcoinUnits::BTC);
-    nDisplayUnit = settings.value("nDisplayUnit").toInt();
+    if (!settings.contains("DisplayBitcoinUnit")) {
+        settings.setValue("DisplayBitcoinUnit", QVariant::fromValue(BitcoinUnit::BTC));
+    }
+    QVariant unit = settings.value("DisplayBitcoinUnit");
+    if (unit.canConvert<BitcoinUnit>()) {
+        m_display_bitcoin_unit = unit.value<BitcoinUnit>();
+    } else {
+        m_display_bitcoin_unit = BitcoinUnit::BTC;
+        settings.setValue("DisplayBitcoinUnit", QVariant::fromValue(m_display_bitcoin_unit));
+    }
 
     if (!settings.contains("strThirdPartyTxUrls"))
         settings.setValue("strThirdPartyTxUrls", "");
@@ -376,7 +384,7 @@ QVariant OptionsModel::data(const QModelIndex & index, int role) const
             return m_sub_fee_from_amount;
 #endif
         case DisplayUnit:
-            return nDisplayUnit;
+            return QVariant::fromValue(m_display_bitcoin_unit);
         case ThirdPartyTxUrls:
             return strThirdPartyTxUrls;
         case Language:
@@ -584,16 +592,13 @@ bool OptionsModel::setData(const QModelIndex & index, const QVariant & value, in
     return successful;
 }
 
-/** Updates current unit in memory, settings and emits displayUnitChanged(newUnit) signal */
-void OptionsModel::setDisplayUnit(const QVariant &value)
+void OptionsModel::setDisplayUnit(const QVariant& new_unit)
 {
-    if (!value.isNull())
-    {
-        QSettings settings;
-        nDisplayUnit = value.toInt();
-        settings.setValue("nDisplayUnit", nDisplayUnit);
-        Q_EMIT displayUnitChanged(nDisplayUnit);
-    }
+    if (new_unit.isNull() || new_unit.value<BitcoinUnit>() == m_display_bitcoin_unit) return;
+    m_display_bitcoin_unit = new_unit.value<BitcoinUnit>();
+    QSettings settings;
+    settings.setValue("DisplayBitcoinUnit", QVariant::fromValue(m_display_bitcoin_unit));
+    Q_EMIT displayUnitChanged(m_display_bitcoin_unit);
 }
 
 void OptionsModel::setRestartRequired(bool fRequired)