Use std::string_view in logging code

src/script/common/c_internal.cpp

@@ -122,27 +122,30 @@ void script_error(lua_State *L, int pcall_result, const char *mod, const char *f
 	throw LuaError(err_msg);
 }
 
-static void script_log_add_source(lua_State *L, std::string &message, int stack_depth)
+[[nodiscard]] static std::string script_log_add_source(lua_State *L,
+	std::string_view message, int stack_depth)
 {
+	std::string ret(message);
 	if (stack_depth <= 0)
-		return;
+		return ret;
 
 	lua_Debug ar;
 	if (lua_getstack(L, stack_depth, &ar)) {
 		FATAL_ERROR_IF(!lua_getinfo(L, "Sl", &ar), "lua_getinfo() failed");
-		message.append(" (at " + std::string(ar.short_src) + ":"
+		ret.append(" (at ").append(ar.short_src).append(":"
 			+ std::to_string(ar.currentline) + ")");
 	} else {
-		message.append(" (at ?:?)");
+		ret.append(" (at ?:?)");
 	}
+	return ret;
 }
 
-bool script_log_unique(lua_State *L, std::string message, std::ostream &log_to,
+bool script_log_unique(lua_State *L, std::string_view message_in, std::ostream &log_to,
 	int stack_depth)
 {
 	thread_local std::vector<u64> logged_messages;
 
-	script_log_add_source(L, message, stack_depth);
+	auto message = script_log_add_source(L, message_in, stack_depth);
 	u64 hash = murmur_hash_64_ua(message.data(), message.length(), 0xBADBABE);
 
 	if (std::find(logged_messages.begin(), logged_messages.end(), hash)
@@ -174,7 +177,7 @@ DeprecatedHandlingMode get_deprecated_handling_mode()
 	return ret;
 }
 
-void log_deprecated(lua_State *L, std::string message, int stack_depth, bool once)
+void log_deprecated(lua_State *L, std::string_view message, int stack_depth, bool once)
 {
 	DeprecatedHandlingMode mode = get_deprecated_handling_mode();
 	if (mode == DeprecatedHandlingMode::Ignore)
@@ -184,12 +187,12 @@ void log_deprecated(lua_State *L, std::string message, int stack_depth, bool onc
 	if (once) {
 		log = script_log_unique(L, message, warningstream, stack_depth);
 	} else {
-		script_log_add_source(L, message, stack_depth);
-		warningstream << message << std::endl;
+		auto message2 = script_log_add_source(L, message, stack_depth);
+		warningstream << message2 << std::endl;
 	}
 
 	if (mode == DeprecatedHandlingMode::Error)
-		throw LuaError(message);
+		throw LuaError(std::string(message));
 	else if (log)
 		infostream << script_get_backtrace(L) << std::endl;
 }

src/script/common/c_internal.h

@@ -26,6 +26,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #pragma once
 
+#include <string_view>
+
 extern "C" {
 #include <lua.h>
 #include <lauxlib.h>
@@ -127,7 +129,7 @@ int script_error_handler(lua_State *L);
 // Takes an error from lua_pcall and throws it as a LuaError
 void script_error(lua_State *L, int pcall_result, const char *mod, const char *fxn);
 
-bool script_log_unique(lua_State *L, std::string message, std::ostream &log_to,
+bool script_log_unique(lua_State *L, std::string_view message, std::ostream &log_to,
 	int stack_depth = 1);
 
 enum DeprecatedHandlingMode {
@@ -152,7 +154,8 @@ DeprecatedHandlingMode get_deprecated_handling_mode();
  *        (ie: not builtin or core). -1 to disabled.
  * @param once Log the deprecation warning only once per callsite.
  */
-void log_deprecated(lua_State *L, std::string message, int stack_depth = 1, bool once = false);
+void log_deprecated(lua_State *L, std::string_view message,
+	int stack_depth = 1, bool once = false);
 
 // Safely call string.dump on a function value
 // (does not pop, leaves one value on stack)

src/script/lua_api/l_util.cpp

@@ -61,13 +61,13 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 int ModApiUtil::l_log(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
-	std::string text;
+	std::string_view text;
 	LogLevel level = LL_NONE;
-	if (lua_isnone(L, 2)) {
-		text = luaL_checkstring(L, 1);
+	if (lua_isnoneornil(L, 2)) {
+		text = readParam<std::string_view>(L, 1);
 	} else {
-		std::string name = luaL_checkstring(L, 1);
-		text = luaL_checkstring(L, 2);
+		auto name = readParam<std::string_view>(L, 1);
+		text = readParam<std::string_view>(L, 2);
 		if (name == "deprecated") {
 			log_deprecated(L, text, 2);
 			return 0;
@@ -75,7 +75,7 @@ int ModApiUtil::l_log(lua_State *L)
 		level = Logger::stringToLevel(name);
 		if (level == LL_MAX) {
 			warningstream << "Tried to log at unknown level '" << name
-				<< "'.  Defaulting to \"none\"." << std::endl;
+				<< "'. Defaulting to \"none\"." << std::endl;
 			level = LL_NONE;
 		}
 	}