Perform a clean Gradle build if android plugins changed

Fixes #38986

platform/android/export/export.cpp

@@ -254,6 +254,8 @@ class EditorExportPlatformAndroid : public EditorExportPlatform {
 	};
 
 	Vector<PluginConfig> plugins;
+	String last_plugin_names;
+	uint64_t last_custom_build_time = 0;
 	volatile bool plugins_changed;
 	Mutex plugins_lock;
 	Vector<Device> devices;
@@ -1831,6 +1833,29 @@ public:
 		return list;
 	}
 
+	inline bool is_clean_build_required(Vector<PluginConfig> enabled_plugins) {
+		String plugin_names = get_plugins_names(enabled_plugins);
+		bool first_build = last_custom_build_time == 0;
+		bool have_plugins_changed = false;
+
+		if (!first_build) {
+			have_plugins_changed = plugin_names != last_plugin_names;
+			if (!have_plugins_changed) {
+				for (int i = 0; i < enabled_plugins.size(); i++) {
+					if (enabled_plugins.get(i).last_updated > last_custom_build_time) {
+						have_plugins_changed = true;
+						break;
+					}
+				}
+			}
+		}
+
+		last_custom_build_time = OS::get_singleton()->get_unix_time();
+		last_plugin_names = plugin_names;
+
+		return have_plugins_changed || first_build;
+	}
+
 	virtual Error export_project(const Ref<EditorExportPreset> &p_preset, bool p_debug, const String &p_path, int p_flags = 0) {
 		ExportNotifier notifier(*this, p_preset, p_debug, p_path, p_flags);
 
@@ -1877,8 +1902,12 @@ public:
 			String local_plugins_binaries = get_plugins_binaries(BINARY_TYPE_LOCAL, enabled_plugins);
 			String remote_plugins_binaries = get_plugins_binaries(BINARY_TYPE_REMOTE, enabled_plugins);
 			String custom_maven_repos = get_plugins_custom_maven_repos(enabled_plugins);
+			bool clean_build_required = is_clean_build_required(enabled_plugins);
 
 			List<String> cmdline;
+			if (clean_build_required) {
+				cmdline.push_back("clean");
+			}
 			cmdline.push_back("build");
 			cmdline.push_back("-Pexport_package_name=" + package_name); // argument to specify the package name.
 			cmdline.push_back("-Pplugins_local_binaries=" + local_plugins_binaries); // argument to specify the list of plugins local dependencies.

platform/android/plugin/godot_plugin_config.h

@@ -70,6 +70,8 @@ The `dependencies` section and fields are optional and defined as follow:
 struct PluginConfig {
 	// Set to true when the config file is properly loaded.
 	bool valid_config = false;
+	// Unix timestamp of last change to this plugin.
+	uint64_t last_updated = 0;
 
 	// Required config section
 	String name;
@@ -87,6 +89,7 @@ struct PluginConfig {
  */
 static const PluginConfig GODOT_PAYMENT = {
 	/*.valid_config =*/true,
+	/*.last_updated =*/0,
 	/*.name =*/"GodotPayment",
 	/*.binary_type =*/"local",
 	/*.binary =*/"res://android/build/libs/plugins/GodotPayment.release.aar",
@@ -150,6 +153,18 @@ static inline bool is_plugin_config_valid(PluginConfig plugin_config) {
 	return valid_name && valid_binary && valid_binary_type && valid_local_dependencies;
 }
 
+static inline uint64_t get_plugin_modification_time(const PluginConfig &plugin_config, const String &config_path) {
+	uint64_t last_updated = FileAccess::get_modified_time(config_path);
+	last_updated = MAX(last_updated, FileAccess::get_modified_time(plugin_config.binary));
+
+	for (int i = 0; i < plugin_config.local_dependencies.size(); i++) {
+		String binary = plugin_config.local_dependencies.get(i);
+		last_updated = MAX(last_updated, FileAccess::get_modified_time(binary));
+	}
+
+	return last_updated;
+}
+
 static inline PluginConfig load_plugin_config(Ref<ConfigFile> config_file, const String &path) {
 	PluginConfig plugin_config = {};
 
@@ -177,6 +192,7 @@ static inline PluginConfig load_plugin_config(Ref<ConfigFile> config_file, const
 			}
 
 			plugin_config.valid_config = is_plugin_config_valid(plugin_config);
+			plugin_config.last_updated = get_plugin_modification_time(plugin_config, path);
 		}
 	}