Decouple clearing condition cache from evaluating general messages

cpp/include/loot/database_interface.h

@@ -120,6 +120,18 @@ public:
    */
   virtual bool Evaluate(const std::string& condition) const = 0;
 
+  /**
+   * @brief Clears the cache of metadata condition evaluation results.
+   * @details As many conditions involve reading files and/or directories,
+   *          libloot caches the results of condition evaluation and reuses
+   *          those cached results in subsequent evaluations.
+   *
+   *          Clearing the condition cache means that the next time a condition
+   *          is evaluated, it will be evaluated from scratch instead of using a
+   *          cached result.
+   */
+  virtual void ClearConditionCache() = 0;
+
   /**
    * @}
    * @name Non-plugin Data Access

cpp/src/api/database.cpp

@@ -52,6 +52,14 @@ bool Database::Evaluate(const std::string& condition) const {
   }
 }
 
+void Database::ClearConditionCache() {
+  try {
+    return database_->clear_condition_cache();
+  } catch (const ::rust::Error& e) {
+    std::rethrow_exception(mapError(e));
+  }
+}
+
 std::vector<std::string> Database::GetKnownBashTags() const {
   try {
     return convert<std::string>(database_->known_bash_tags());

cpp/src/api/database.h

@@ -26,6 +26,8 @@ public:
 
   bool Evaluate(const std::string& condition) const override;
 
+  void ClearConditionCache() override;
+
   std::vector<std::string> GetKnownBashTags() const override;
 
   std::vector<Message> GetGeneralMessages(

cpp/src/database.rs

@@ -94,6 +94,15 @@ impl Database {
             .map_err(Into::into)
     }
 
+    pub fn clear_condition_cache(&self) -> Result<(), VerboseError> {
+        self.0
+            .write()
+            .map_err(DatabaseLockPoisonError::from)?
+            .clear_condition_cache();
+
+        Ok(())
+    }
+
     pub fn known_bash_tags(&self) -> Result<Vec<String>, VerboseError> {
         Ok(self
             .0

cpp/src/lib.rs

@@ -266,6 +266,8 @@ mod ffi {
 
         pub fn evaluate(&self, condition: &str) -> Result<bool>;
 
+        pub fn clear_condition_cache(&self) -> Result<()>;
+
         pub fn known_bash_tags(&self) -> Result<Vec<String>>;
 
         pub fn general_messages(&self, evaluate_conditions: bool) -> Result<Vec<Message>>;

cpp/src/tests/api/interface/database_interface_test.h

@@ -277,6 +277,21 @@ TEST_P(DatabaseInterfaceTest, evaluateShouldReturnFalseIfTheConditionIsFalse) {
   EXPECT_FALSE(handle_->GetDatabase().Evaluate("file(\"missing.esp\")"));
 }
 
+TEST_P(DatabaseInterfaceTest,
+    clearConditionCacheShouldCauseConditionsToBeEvaluatedFromScratch) {
+  const auto condition = "file(\"Blank.esp\")";
+
+  EXPECT_TRUE(handle_->GetDatabase().Evaluate(condition));
+
+  std::filesystem::remove(dataPath / "Blank.esp");
+
+  EXPECT_TRUE(handle_->GetDatabase().Evaluate(condition));
+
+  handle_->GetDatabase().ClearConditionCache();
+
+  EXPECT_FALSE(handle_->GetDatabase().Evaluate(condition));
+}
+
 TEST_P(DatabaseInterfaceTest,
        getGroupsShouldReturnAllGroupsListedInTheLoadedMetadata) {
   ASSERT_NO_THROW(GenerateMasterlist());