This adds the additional safety features. stack_guard should probably be migrated into the tests too, since a lesser form is already used there.

Closes #54 #55

sol/coroutine.hpp

@@ -67,7 +67,11 @@ private:
     }
 
 public:
-    coroutine(lua_State* L, int index = -1) noexcept : reference(L, index) {}
+    coroutine(lua_State* L, int index = -1) : reference(L, index) {
+#ifdef SOL_CHECK_ARGUMENTS
+        type_assert(L, index, type::function);
+#endif // Safety
+    }
     coroutine() noexcept = default;
     coroutine(const coroutine&) noexcept = default;
     coroutine& operator=(const coroutine&) noexcept = default;

sol/function.hpp

@@ -65,7 +65,16 @@ private:
     }
 
 public:
-    using reference::reference;
+    function() = default;
+    function(const function&) = default;
+    function& operator=(const function&) = default;
+    function( function&& ) = default;
+    function& operator=( function&& ) = default;
+    function(lua_State* L, int index = -1): reference(L, index) {
+#ifdef SOL_CHECK_ARGUMENTS
+        type_assert(L, index, type::function);
+#endif // Safety
+    }
     
     template<typename... Args>
     function_result operator()( Args&&... args ) const {

sol/protected_function.hpp

@@ -130,13 +130,15 @@ public:
     reference error_handler;
 
     protected_function() = default;
-    protected_function(lua_State* L, int index = -1): reference(L, index), error_handler(get_default_handler()) {
-        type_assert(L, index, type::function);
-    }
     protected_function(const protected_function&) = default;
     protected_function& operator=(const protected_function&) = default;
     protected_function( protected_function&& ) = default;
     protected_function& operator=( protected_function&& ) = default;
+    protected_function(lua_State* L, int index = -1): reference(L, index), error_handler(get_default_handler()) {
+#ifdef SOL_CHECK_ARGUMENTS
+        type_assert(L, index, type::function);
+#endif // Safety
+    }
 
     template<typename... Args>
     protected_function_result operator()(Args&&... args) const {

sol/stack_get.hpp

@@ -148,6 +148,18 @@ struct getter<c_closure> {
 	}
 };
 
+template<>
+struct getter<error> {
+    static error get(lua_State* L,  int index = -1) {
+        size_t sz = 0;
+        const char* err = lua_tolstring(L, index, &sz);
+        if (err == nullptr) {
+            return error(detail::direct_error, "");
+        }
+        return error(detail::direct_error, std::string(err, sz));
+    }
+};
+
 template<>
 struct getter<void*> {
     static void* get(lua_State* L, int index = -1) {

sol/stack_guard.hpp

@@ -0,0 +1,59 @@
+// The MIT License (MIT) 
+
+// Copyright (c) 2013-2016 Rapptz, ThePhD and contributors
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy of
+// this software and associated documentation files (the "Software"), to deal in
+// the Software without restriction, including without limitation the rights to
+// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+// the Software, and to permit persons to whom the Software is furnished to do so,
+// subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+#ifndef SOL_STACK_GUARD_HPP
+#define SOL_STACK_GUARD_HPP
+
+#include "compatibility/version.hpp"
+#include "error.hpp"
+#include <functional>
+
+namespace sol {
+namespace detail {
+inline void stack_fail(int, int) {
+#ifndef SOL_NO_EXCEPTIONS
+    throw error(detail::direct_error, "imbalanced stack after operation finish");
+#else
+    // Lol, what do you want, an error printout? :3c
+    // There's no sane default here. The right way would be C-style abort(), and that's not acceptable, so
+    // hopefully someone will register their own stack_fail thing here
+#endif // No Exceptions
+}
+} // detail
+
+struct stack_guard {
+    lua_State* L;
+    int top;
+    std::function<void(int, int)> fx;
+
+    stack_guard(lua_State* L) : stack_guard(L, lua_gettop(L)) {}
+    stack_guard(lua_State* L, int top, std::function<void(int, int)> fx = detail::stack_fail) : L(L), top(top), fx(std::move(fx)) {}
+    ~stack_guard() {
+        int bottom = lua_gettop(L);
+        if (top == bottom) {
+            return;
+        }
+	   fx(top, bottom);
+    }
+};
+} // sol
+
+#endif // SOL_STACK_GUARD_HPP

sol/table_core.hpp

@@ -152,7 +152,9 @@ public:
     table_core( ) noexcept : reference( ) { }
     table_core( const table_core<true>& global ) noexcept : reference( global ) { }
     table_core( lua_State* L, int index = -1 ) : reference( L, index ) {
+#ifdef SOL_CHECK_ARGUMENTS
         type_assert( L, index, type::table );
+#endif // Safety
     }
 
     table_iterator begin () const {

sol/thread.hpp

@@ -28,7 +28,16 @@
 namespace sol {
 class thread : public reference {
 public:
-    using reference::reference;
+    thread () noexcept = default;
+    thread(const thread&) = default;
+    thread(thread&&) = default;
+    thread& operator=(const thread&) = default;
+    thread& operator=(thread&&) = default;
+    thread(lua_State* L, int index = -1) : reference(L, index) {
+#ifdef SOL_CHECK_ARGUMENTS
+        type_assert(L, index, type::thread);
+#endif // Safety
+    }
 
     state_view state() const {
         return state_view(this->thread_state());

sol/types.hpp

@@ -213,7 +213,7 @@ class coroutine;
 class thread;
 class object;
 class userdata;
-class light_userdata;
+class lightuserdata;
 
 template <typename T, typename = void>
 struct lua_type_of : std::integral_constant<type, type::userdata> {};
@@ -264,7 +264,7 @@ template <>
 struct lua_type_of<userdata_value> : std::integral_constant<type, type::userdata> {};
 
 template <>
-struct lua_type_of<light_userdata> : std::integral_constant<type, type::lightuserdata> {};
+struct lua_type_of<lightuserdata> : std::integral_constant<type, type::lightuserdata> {};
 
 template <>
 struct lua_type_of<userdata> : std::integral_constant<type, type::userdata> {};

sol/userdata.hpp

@@ -27,12 +27,30 @@
 namespace sol {
 class userdata : public reference {
 public:
-    using reference::reference;
+    userdata () noexcept = default;
+    userdata(const userdata&) = default;
+    userdata(userdata&&) = default;
+    userdata& operator=(const userdata&) = default;
+    userdata& operator=(userdata&&) = default;
+    userdata(lua_State* L, int index = -1) : reference(L, index) {
+#ifdef SOL_CHECK_ARGUMENTS
+        type_assert(L, index, type::userdata);
+#endif // Safety
+    }
 };
 
-class light_userdata : public reference {
+class lightuserdata : public reference {
 public:
-    using reference::reference;
+    lightuserdata () noexcept = default;
+    lightuserdata(const lightuserdata&) = default;
+    lightuserdata(lightuserdata&&) = default;
+    lightuserdata& operator=(const lightuserdata&) = default;
+    lightuserdata& operator=(lightuserdata&&) = default;
+    lightuserdata(lua_State* L, int index = -1) : reference(L, index) {
+#ifdef SOL_CHECK_ARGUMENTS
+        type_assert(L, index, type::lightuserdata);
+#endif // Safety
+    }
 };
 
 } // sol