Added CLuaStackChecker

Author: sbx320

Shared/mods/deathmatch/logic/lua/CLuaFunctionParser.h

@@ -12,6 +12,7 @@
 #include <variant>
 #include <SharedUtil.Template.h>
 #include "lua/CLuaFunctionParseHelpers.h"
+#include "lua/CLuaStackChecker.h"
 #include "lua/LuaBasic.h"
 
 template <bool, auto*>
@@ -246,6 +247,8 @@ struct CLuaFunctionParser<ErrorOnFailure, Func>
     template <typename T>
     inline T PopUnsafe(lua_State* L, std::size_t& index)
     {
+        // Expect no change in stack size
+        LUA_STACK_EXPECT(0); 
         // trivial types are directly popped
         if constexpr (std::is_same_v<T, std::string> || std::is_same_v<T, int> || std::is_same_v<T, float> || std::is_same_v<T, double> ||
                       std::is_same_v<T, short> || std::is_same_v<T, unsigned int> || std::is_same_v<T, unsigned short> || std::is_same_v<T, bool>)

Shared/mods/deathmatch/logic/lua/CLuaStackChecker.h

@@ -0,0 +1,56 @@
+/*****************************************************************************
+ *
+ *  PROJECT:     Multi Theft Auto
+ *  LICENSE:     See LICENSE in the top level directory
+ *
+ *  Multi Theft Auto is available from http://www.multitheftauto.com/
+ *
+ *****************************************************************************/
+#pragma once
+#include <stdexcept>
+/*
+ * Simple utility to verify the Lua stack.
+ * The general idea is to simply write
+ *   LUA_STACK_EXPECT(N);
+ * at the beginning of a function, where N
+ * is the expected amount of change in the Lua
+ * stack size.
+ *
+ * As an example: A __index metamethod receives
+ * two parameters on the stack and returns a
+ * single value. Therefor each __index
+ * implementation should decrease the Lua stack
+ * size by one. Therefore write:
+ *   LUA_STACK_EXPECT(-1);
+ */
+namespace lua
+{
+    struct CLuaStackChecker
+    {
+        lua_State* L;
+        int        m_iTop = 0;
+        int        m_iExpected = 0;
+        CLuaStackChecker(lua_State* L, int expected) : L(L)
+        {
+            m_iTop = lua_gettop(L);
+            m_iExpected = expected;
+        }
+
+        ~CLuaStackChecker() noexcept(false)
+        {
+            int iNewtop = lua_gettop(L);
+            int iChange = iNewtop - m_iTop;
+            if (iChange != m_iExpected)
+            {
+                printf("Lua Stack Error: top should be %d is %d (change should be %d is %d)\n", m_iTop + m_iExpected, iNewtop, m_iExpected, iChange);
+                throw std::runtime_error("Lua Stack Error");
+            }
+        }
+    };
+}            // namespace lua
+
+#ifdef MTA_DEBUG
+#define LUA_STACK_EXPECT(i) lua::CLuaStackChecker invalidHiddenName(L, i)
+#else
+#define LUA_STACK_EXPECT(i)
+#endif