[3.x] [Debugger] Add --debug-server CLI option.

Automatically starts the editor debug server at given <IP>:<PORT>.

E.g.:
 # Run editor and debug server listening on any interface, port 8080
godot3 -e --path proj/proj_empty --debug-server *:8080

 # Run the godot project connecting to that debug server.
godot3 --path proj/proj_empty --remote-debug 127.0.0.1:8080

editor/script_editor_debugger.cpp

@@ -1560,8 +1560,10 @@ void ScriptEditorDebugger::_clear_execution() {
 	stack_script.unref();
 }
 
-void ScriptEditorDebugger::start() {
+void ScriptEditorDebugger::start(int p_port, const IP_Address &p_bind_address) {
+	if (is_inside_tree()) {
 		stop();
+	}
 
 	if (is_visible_in_tree()) {
 		EditorNode::get_singleton()->make_bottom_panel_item_visible(this);
@@ -1573,7 +1575,11 @@ void ScriptEditorDebugger::start() {
 	}
 
 	const int max_tries = 6;
+	if (p_port < 0) {
 		remote_port = (int)EditorSettings::get_singleton()->get("network/debug/remote_port");
+	} else {
+		remote_port = p_port;
+	}
 	int current_try = 0;
 	// Find first available port.
 	Error err = server->listen(remote_port);
@@ -1582,7 +1588,7 @@ void ScriptEditorDebugger::start() {
 		current_try++;
 		remote_port++;
 		OS::get_singleton()->delay_usec(1000);
-		err = server->listen(remote_port);
+		err = server->listen(remote_port, p_bind_address);
 	}
 	// No suitable port found.
 	if (err != OK) {
@@ -1592,7 +1598,7 @@ void ScriptEditorDebugger::start() {
 	EditorNode::get_singleton()->get_scene_tree_dock()->show_tab_buttons();
 
 	auto_switch_remote_scene_tree = (bool)EditorSettings::get_singleton()->get("debugger/auto_switch_to_remote_scene_tree");
-	if (auto_switch_remote_scene_tree) {
+	if (is_inside_tree() && auto_switch_remote_scene_tree) {
 		EditorNode::get_singleton()->get_scene_tree_dock()->show_remote_tree();
 	}
 

editor/script_editor_debugger.h

@@ -244,7 +244,7 @@ protected:
 	static void _bind_methods();
 
 public:
-	void start();
+	void start(int p_port = -1, const IP_Address &p_bind_address = IP_Address("*"));
 	void pause();
 	void unpause();
 	void stop();

main/main.cpp

@@ -80,6 +80,7 @@
 #include "editor/editor_translation.h"
 #include "editor/progress_dialog.h"
 #include "editor/project_manager.h"
+#include "editor/script_editor_debugger.h"
 #ifndef NO_EDITOR_SPLASH
 #include "main/splash_editor.gen.h"
 #endif
@@ -133,6 +134,7 @@ static OS::ProcessID allow_focus_steal_pid = 0;
 static bool delta_sync_after_draw = false;
 #ifdef TOOLS_ENABLED
 static bool auto_build_solutions = false;
+static String debug_server_uri;
 #endif
 
 // Display
@@ -257,6 +259,7 @@ void Main::print_help(const char *p_binary) {
 #ifdef TOOLS_ENABLED
 	OS::get_singleton()->print("  -e, --editor                     Start the editor instead of running the scene.\n");
 	OS::get_singleton()->print("  -p, --project-manager            Start the project manager, even if a project is auto-detected.\n");
+	OS::get_singleton()->print("  --debug-server <address>         Start the editor debug server (<IP>:<port>, e.g. 127.0.0.1:6007)\n");
 #endif
 	OS::get_singleton()->print("  -q, --quit                       Quit after the first iteration.\n");
 	OS::get_singleton()->print("  -l, --language <locale>          Use a specific locale (<locale> being a two-letter code).\n");
@@ -733,6 +736,19 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 		} else if (I->get() == "-p" || I->get() == "--project-manager") { // starts project manager
 
 			project_manager = true;
+
+		} else if (I->get() == "--debug-server") {
+			if (I->next()) {
+				debug_server_uri = I->next()->get();
+				if (debug_server_uri.find(":") == -1) { // wrong address
+					OS::get_singleton()->print("Invalid debug server address. It should be of the form <bind_address>:<port>.\n");
+					goto error;
+				}
+				N = I->next()->next();
+			} else {
+				OS::get_singleton()->print("Missing remote debug server server, aborting.\n");
+				goto error;
+			}
 		} else if (I->get() == "--build-solutions") { // Build the scripting solution such C#
 
 			auto_build_solutions = true;
@@ -2063,6 +2079,13 @@ bool Main::start() {
 						ERR_PRINT("Failed to load scene");
 				}
 				OS::get_singleton()->set_context(OS::CONTEXT_EDITOR);
+				// Start debug server.
+				if (!debug_server_uri.empty()) {
+					int idx = debug_server_uri.rfind(":");
+					IP_Address addr = debug_server_uri.substr(0, idx);
+					int port = debug_server_uri.substr(idx + 1).to_int();
+					ScriptEditor::get_singleton()->get_debugger()->start(port, addr);
+				}
 			}
 #endif
 			if (!editor) {