CMake: Make cache clean detection better

Do clean the cache when necessary. The logic used to be wrong in that
it sometimes would just force a reparse where a cache clean was necessary.

Change-Id: Ice5e3bceaea83d4fd4d7c2ae6e21e76118e2d2c0
Reviewed-by: Vikas Pachdha <vikas.pachdha@theqtcompany.com>
Reviewed-by: Tim Jenssen <tim.jenssen@theqtcompany.com>

src/plugins/cmakeprojectmanager/builddirmanager.cpp

@@ -607,6 +607,9 @@ void BuildDirManager::maybeForceReparse()
     const QByteArray EXTRA_GENERATOR_KEY = "CMAKE_EXTRA_GENERATOR";
     const QByteArray CMAKE_COMMAND_KEY = "CMAKE_COMMAND";
 
+    const QByteArrayList criticalKeys
+            = QByteArrayList() << GENERATOR_KEY << EXTRA_GENERATOR_KEY << CMAKE_COMMAND_KEY;
+
     if (!m_hasData) {
         forceReparse();
         return;
@@ -614,6 +617,8 @@ void BuildDirManager::maybeForceReparse()
 
     const CMakeConfig currentConfig = parsedConfiguration();
 
+    const CMakeTool *tool = CMakeKitInformation::cmakeTool(kit());
+    QTC_ASSERT(tool, return); // No cmake... we should not have ended up here in the first place
     const QString kitGenerator = CMakeGeneratorKitInformation::generator(kit());
     int pos = kitGenerator.lastIndexOf(QLatin1String(" - "));
     const QString extraKitGenerator = (pos > 0) ? kitGenerator.left(pos) : QString();
@@ -624,36 +629,41 @@ void BuildDirManager::maybeForceReparse()
     if (!extraKitGenerator.isEmpty())
         targetConfig.append(CMakeConfigItem(EXTRA_GENERATOR_KEY, CMakeConfigItem::INTERNAL,
                                             QByteArray(), extraKitGenerator.toUtf8()));
-    const CMakeTool *tool = CMakeKitInformation::cmakeTool(kit());
-    if (tool)
     targetConfig.append(CMakeConfigItem(CMAKE_COMMAND_KEY, CMakeConfigItem::INTERNAL,
                                         QByteArray(), tool->cmakeExecutable().toUserOutput().toUtf8()));
     Utils::sort(targetConfig, CMakeConfigItem::sortOperator());
 
+    bool mustReparse = false;
     auto ccit = currentConfig.constBegin();
     auto kcit = targetConfig.constBegin();
+
     while (ccit != currentConfig.constEnd() && kcit != targetConfig.constEnd()) {
         if (ccit->key == kcit->key) {
-            if (ccit->value != kcit->value)
+            if (ccit->value != kcit->value) {
-                break;
+                if (criticalKeys.contains(kcit->key)) {
+                        clearCache();
+                        return;
+                }
+                mustReparse = true;
+            }
             ++ccit;
             ++kcit;
         } else {
-            if (ccit->key < kcit->key)
+            if (ccit->key < kcit->key) {
                 ++ccit;
-            else
+            } else {
-                break;
+                ++kcit;
+                mustReparse = true;
+            }
         }
     }
 
-    if (kcit != targetConfig.end()) {
+    // If we have keys that do not exist yet, then reparse.
-        if (kcit->key == GENERATOR_KEY
+    //
-                || kcit->key == EXTRA_GENERATOR_KEY
+    // The critical keys *must* be set in cmake configuration, so those were already
-                || kcit->key == CMAKE_COMMAND_KEY)
+    // handled above.
-            clearCache();
+    if (mustReparse || kcit != targetConfig.constEnd())
-        else
         forceReparse();
-    }
 }
 
 } // namespace Internal