CMakePM: Add default kit configuration hashing

This adds a QTC_KIT_DEFAULT_CONFIG_HASH variable containing the hash of
all the default Qt Creator CMake kit variables:
  * CMAKE_C_COMPILER
  * CMAKE_CXX_COMPILER
  * QT_QMAKE_EXECUTABLE
  * CMAKE_PREFIX_PATH

This way when a CMake preset changes any of these CMake variables a new
Kit will be created. Otherwise a previous kit containing different
values will be used.

Fixes: QTCREATORBUG-28609
Change-Id: I77b67e9c8fa15dc3ff2f22c5b63d4ca1c7670fdc
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/cmakeprojectmanager/cmakekitinformation.cpp

@@ -39,6 +39,7 @@
 #include <utils/variablechooser.h>
 
 #include <QComboBox>
+#include <QCryptographicHash>
 #include <QDialog>
 #include <QDialogButtonBox>
 #include <QGridLayout>
@@ -875,6 +876,7 @@ const char CMAKE_CXX_TOOLCHAIN_KEY[] = "CMAKE_CXX_COMPILER";
 const char CMAKE_QMAKE_KEY[] = "QT_QMAKE_EXECUTABLE";
 const char CMAKE_PREFIX_PATH_KEY[] = "CMAKE_PREFIX_PATH";
 const char QTC_CMAKE_PRESET_KEY[] = "QTC_CMAKE_PRESET";
+const char QTC_KIT_DEFAULT_CONFIG_HASH[] = "QTC_KIT_DEFAULT_CONFIG_HASH";
 
 class CMakeConfigurationKitAspectWidget final : public KitAspectWidget
 {
@@ -1135,6 +1137,43 @@ CMakeConfigItem CMakeConfigurationKitAspect::cmakePresetConfigItem(const Project
     });
 }
 
+void CMakeConfigurationKitAspect::setKitDefaultConfigHash(ProjectExplorer::Kit *k)
+{
+    const CMakeConfig defaultConfigExpanded
+        = Utils::transform(defaultConfiguration(k).toList(), [k](const CMakeConfigItem &item) {
+              CMakeConfigItem expanded(item);
+              expanded.value = item.expandedValue(k).toUtf8();
+              return expanded;
+          });
+    const QByteArray kitHash = computeDefaultConfigHash(defaultConfigExpanded);
+
+    CMakeConfig config = configuration(k);
+    config.append(CMakeConfigItem(QTC_KIT_DEFAULT_CONFIG_HASH, CMakeConfigItem::INTERNAL, kitHash));
+
+    setConfiguration(k, config);
+}
+
+CMakeConfigItem CMakeConfigurationKitAspect::kitDefaultConfigHashItem(const ProjectExplorer::Kit *k)
+{
+    const CMakeConfig config = configuration(k);
+    return Utils::findOrDefault(config, [](const CMakeConfigItem &item) {
+        return item.key == QTC_KIT_DEFAULT_CONFIG_HASH;
+    });
+}
+
+QByteArray CMakeConfigurationKitAspect::computeDefaultConfigHash(const CMakeConfig &config)
+{
+    const CMakeConfig defaultConfig = defaultConfiguration(nullptr);
+    const QByteArray configValues = std::accumulate(defaultConfig.begin(),
+                                                    defaultConfig.end(),
+                                                    QByteArray(),
+                                                    [config](QByteArray &sum,
+                                                             const CMakeConfigItem &item) {
+                                                        return sum += config.valueOf(item.key);
+                                                    });
+    return QCryptographicHash::hash(configValues, QCryptographicHash::Md5).toHex();
+}
+
 QVariant CMakeConfigurationKitAspect::defaultValue(const Kit *k) const
 {
     // FIXME: Convert preload scripts