Add error message when trying to load project from CWD.

core/os/os.cpp

@@ -408,6 +408,10 @@ Error OS::set_cwd(const String &p_cwd) {
 	return ERR_CANT_OPEN;
 }
 
+String OS::get_cwd() const {
+	return ".";
+}
+
 Dictionary OS::get_memory_info() const {
 	Dictionary meminfo;
 

core/os/os.h

@@ -205,6 +205,7 @@ class OS {
 	virtual Error shell_open(const String &p_uri);
 	virtual Error shell_show_in_file_manager(String p_path, bool p_open_folder = true);
 	virtual Error set_cwd(const String &p_cwd);
+	virtual String get_cwd() const;
 
 	virtual bool has_environment(const String &p_var) const = 0;
 	virtual String get_environment(const String &p_var) const = 0;

drivers/unix/os_unix.cpp

@@ -1096,6 +1096,16 @@ Error OS_Unix::set_cwd(const String &p_cwd) {
 	return OK;
 }
 
+String OS_Unix::get_cwd() const {
+	String dir;
+	char real_current_dir_name[2048];
+	ERR_FAIL_NULL_V(getcwd(real_current_dir_name, 2048), ".");
+	if (dir.append_utf8(real_current_dir_name) != OK) {
+		dir = real_current_dir_name;
+	}
+	return dir;
+}
+
 bool OS_Unix::has_environment(const String &p_var) const {
 	return getenv(p_var.utf8().get_data()) != nullptr;
 }

drivers/unix/os_unix.h

@@ -101,6 +101,7 @@ class OS_Unix : public OS {
 	virtual Error get_dynamic_library_symbol_handle(void *p_library_handle, const String &p_name, void *&p_symbol_handle, bool p_optional = false) override;
 
 	virtual Error set_cwd(const String &p_cwd) override;
+	virtual String get_cwd() const override;
 
 	virtual String get_name() const override;
 	virtual String get_distribution_name() const override;

main/main.cpp

@@ -992,6 +992,7 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 	OS::get_singleton()->initialize();
 
 #if !defined(OVERRIDE_PATH_ENABLED) && !defined(TOOLS_ENABLED)
+	String old_cwd = OS::get_singleton()->get_cwd();
 #ifdef MACOS_ENABLED
 	String new_cwd = OS::get_singleton()->get_bundle_resource_dir();
 	if (new_cwd.is_empty() || !new_cwd.is_absolute_path()) {
@@ -2019,8 +2020,23 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 #ifdef TOOLS_ENABLED
 		editor = false;
 #else
-		const String error_msg = "Error: Couldn't load project data at path \"" + project_path + "\". Is the .pck file missing?\nIf you've renamed the executable, the associated .pck file should also be renamed to match the executable's name (without the extension).\n";
-		OS::get_singleton()->print("%s", error_msg.utf8().get_data());
+		String error_msg = "Error: Couldn't load project data at path \"" + (project_path == "." ? OS::get_singleton()->get_cwd() : project_path) + "\". Is the .pck file missing?\n\n";
+#if !defined(OVERRIDE_PATH_ENABLED) && !defined(TOOLS_ENABLED)
+		String exec_path = OS::get_singleton()->get_executable_path();
+		String exec_basename = exec_path.get_file().get_basename();
+
+		if (FileAccess::exists(old_cwd.path_join(exec_basename + ".pck"))) {
+			error_msg += "\"" + exec_basename + ".pck\" was found in the current working directory. To be able to load a project from the CWD, use the `disable_path_overrides=no` SCons option when compiling Godot.\n";
+		} else if (FileAccess::exists(old_cwd.path_join("project.godot"))) {
+			error_msg += "\"project.godot\" was found in the current working directory. To be able to load a project from the CWD, use the `disable_path_overrides=no` SCons option when compiling Godot.\n";
+		} else {
+			error_msg += "If you've renamed the executable, the associated .pck file should also be renamed to match the executable's name (without the extension).\n";
+		}
+#else
+		error_msg += "If you've renamed the executable, the associated .pck file should also be renamed to match the executable's name (without the extension).\n";
+#endif
+		ERR_PRINT(error_msg);
+
 		OS::get_singleton()->alert(error_msg);
 
 		goto error;

platform/windows/os_windows.cpp

@@ -1678,6 +1678,14 @@ Error OS_Windows::set_cwd(const String &p_cwd) {
 	return OK;
 }
 
+String OS_Windows::get_cwd() const {
+	Char16String real_current_dir_name;
+	size_t str_len = GetCurrentDirectoryW(0, nullptr);
+	real_current_dir_name.resize_uninitialized(str_len + 1);
+	GetCurrentDirectoryW(real_current_dir_name.size(), (LPWSTR)real_current_dir_name.ptrw());
+	return String::utf16((const char16_t *)real_current_dir_name.get_data()).trim_prefix(R"(\\?\)").replace_char('\\', '/');
+}
+
 Vector<String> OS_Windows::get_system_fonts() const {
 	if (!dwrite_init) {
 		return Vector<String>();

platform/windows/os_windows.h

@@ -201,6 +201,7 @@ class OS_Windows : public OS {
 	virtual double get_unix_time() const override;
 
 	virtual Error set_cwd(const String &p_cwd) override;
+	virtual String get_cwd() const override;
 
 	virtual void add_frame_delay(bool p_can_draw, bool p_wake_for_events) override;
 	virtual void delay_usec(uint32_t p_usec) const override;