McuSupport: Read and write user settings with non-versioned key

The settings keys are versioned to avoid the situation where the
installer removes a settings key which may still be in use.
See QTCREATORBUG-29194 for details.

When reading from user settings, it makes more sense to use the
non-versioned keys, especially in the case of the main Qt for MCUs
SDK package path. With this patch, the plain settings key is used
to read and write except for when determining the default value of a
path in the McuPackage constructor, where we want to also look in the
system scope settings for the values written by the installer, which
may be version specific

Task-number: QTCREATORBUG-30810
Change-Id: Ib1e2be170cb7da24b6e4534b59f702b894556d8c
Reviewed-by: Yasser Grimes <yasser.grimes@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/mcusupport/mcupackage.cpp

@@ -43,11 +43,11 @@ McuPackage::McuPackage(const SettingsHandler::Ptr &settingsHandler,
                        const McuPackageVersionDetector *versionDetector,
                        const bool addToSystemPath,
                        const Utils::PathChooser::Kind &valueType,
-                       const bool useNewestVersionKey)
+                       const bool allowNewerVersionKey)
     : settingsHandler(settingsHandler)
     , m_label(label)
     , m_detectionPaths(detectionPaths)
-    , m_settingsKey(settingsHandler->getVersionedKey(settingsKey, QSettings::SystemScope, versions, useNewestVersionKey))
+    , m_settingsKey(settingsKey)
     , m_versionDetector(versionDetector)
     , m_versions(versions)
     , m_cmakeVariableName(cmakeVarName)
@@ -56,8 +56,18 @@ McuPackage::McuPackage(const SettingsHandler::Ptr &settingsHandler,
     , m_addToSystemPath(addToSystemPath)
     , m_valueType(valueType)
 {
-    m_defaultPath = settingsHandler->getPath(m_settingsKey, QSettings::SystemScope, defaultPath);
+    // The installer writes versioned keys as well as the plain key as found in the kits.
-    m_path = settingsHandler->getPath(m_settingsKey, QSettings::UserScope, m_defaultPath);
+    // Use the versioned key in case the plain key was removed by an uninstall operation
+    const Utils::Key versionedKey = settingsHandler->getVersionedKey(settingsKey,
+                                                                     QSettings::SystemScope,
+                                                                     versions,
+                                                                     allowNewerVersionKey);
+    m_defaultPath = settingsHandler->getPath(versionedKey, QSettings::SystemScope, defaultPath);
+    m_path = settingsHandler->getPath(m_settingsKey, QSettings::UserScope, "");
+    // The user settings may have been written with a versioned key in older versions of QtCreator
+    if (m_path.isEmpty()) {
+        m_path = settingsHandler->getPath(versionedKey, QSettings::UserScope, m_defaultPath);
+    }
     if (m_path.isEmpty()) {
         m_path = FilePath::fromUserInput(qtcEnvironmentVariable(m_environmentVariableName));
     }

src/plugins/mcusupport/mcupackage.h

@@ -41,7 +41,7 @@ public:
                const bool addToPath = false,
                const Utils::PathChooser::Kind &valueType
                = Utils::PathChooser::Kind::ExistingDirectory,
-               const bool useNewestVersionKey = false);
+               const bool allowNewerVersionKey = false);
 
     ~McuPackage() override = default;
 

src/plugins/mcusupport/settingshandler.cpp

@@ -105,12 +105,24 @@ FilePath SettingsHandler::getPath(const Key &settingsKey,
 
 bool SettingsHandler::write(const Key &settingsKey,
                             const FilePath &path,
-                            const FilePath &defaultPath) const
+                            const FilePath &maybeDefaultPath) const
 {
     const FilePath savedPath = packagePathFromSettings(settingsKey,
                                                        *Core::ICore::settings(QSettings::UserScope),
-                                                       defaultPath);
+                                                       maybeDefaultPath);
     const Key key = Key(Constants::SETTINGS_GROUP) + '/' + Constants::SETTINGS_KEY_PACKAGE_PREFIX + settingsKey;
+
+    FilePath defaultPath = maybeDefaultPath;
+    if (path == maybeDefaultPath) {
+        // If the installer has overwritten the non-versioned key with an older version than the
+        // newest versioned key, and the user wants to manually return to the newest installed
+        // version, the defaultPath will match the desired path, and the settings object will
+        // assume it can simply remove the key instead of writing a new value to it.
+        // To work around this, pretend like the default value is the value found from the global scope
+        defaultPath = packagePathFromSettings(settingsKey,
+                                              *Core::ICore::settings(QSettings::SystemScope),
+                                              maybeDefaultPath);;
+    }
     Core::ICore::settings()->setValueWithDefault(key,
                                                  path.toUserOutput(),
                                                  defaultPath.toUserOutput());