Improved functions example and adjusted all errors for g++ conformance with -Wall -Werror

examples/functions.cpp

@@ -15,6 +15,10 @@ struct multiplier {
     }
 };
 
+inline std::string make_string( std::string input ) { 
+	return "string: " + input;
+}
+
 int main() {
 	sol::state lua;
 	lua.open_libraries(sol::lib::base);
@@ -50,11 +54,13 @@ int main() {
 	// retrieval of a function is done similarly
 	// to other variables, using sol::function
 	sol::function add = lua["my_add"];
+	int value = add(10, 11);
 	assert(add.call<int>(10, 11) == 21);
+	assert(value == 21);
 
 	// multi-return functions are supported using
 	// std::tuple as the interface.
-    lua.set_function("multi", []{ return std::make_tuple(10, "goodbye"); });
+	lua.set_function("multi", [] { return std::make_tuple(10, "goodbye"); });
 	lua.script("x, y = multi()");
 	lua.script("assert(x == 10 and y == 'goodbye')");
 
@@ -63,7 +69,22 @@ int main() {
 	std::string second;
 	std::tie(first, second) = multi.call<int, std::string>();
 
-    // assert the values
+	// use the values
 	assert(first == 10);
 	assert(second == "goodbye");
+
+	// you can even overload functions
+	// just pass in the different functions
+	// you want to pack into a single name:
+	// make SURE they take different number of
+	// arguments/different types!
+	
+	lua.set_function("func", sol::overload([](int x) { return x; }, make_string, my_add));
+
+	// All these functions are now overloaded through "func"
+	lua.script(R"(
+print(func(1))
+print(func("bark"))
+print(func(1,2))
+)");
 }

sol/function.hpp

@@ -386,14 +386,13 @@ struct pusher<overload_set<Functions...>> {
 template<typename Signature>
 struct getter<std::function<Signature>> {
     typedef function_traits<Signature> fx_t;
-    typedef typename fx_t::args_type args_t;
-    typedef typename tuple_types_t<typename fx_t::return_type> ret_t;
+    typedef typename fx_t::args_type args_type;
+    typedef tuple_types_t<typename fx_t::return_type> return_type;
 
     template<typename... FxArgs, typename... Ret>
     static std::function<Signature> get_std_func(types<FxArgs...>, types<Ret...>, lua_State* L, int index = -1) {
-        typedef typename function_traits<Signature>::return_type return_t;
         sol::function f(L, index);
-        auto fx = [f, L, index](FxArgs&&... args) -> return_t {
+        auto fx = [f, L, index](FxArgs&&... args) -> return_type_t<Ret...> {
             return f(types<Ret...>(), std::forward<FxArgs>(args)...);
         };
         return std::move(fx);
@@ -414,7 +413,7 @@ struct getter<std::function<Signature>> {
     }
 
     static std::function<Signature> get(lua_State* L, int index) {
-        return get_std_func(args_t(), ret_t(), L, index);
+        return get_std_func(args_type(), return_type(), L, index);
     }
 };
 } // stack

sol/function_result.hpp

@@ -89,11 +89,6 @@ public:
         return get(tr, tr);
     }
 
-    template <typename K>
-    decltype(auto) operator[](K&& key) const {
-        return get<table>()[std::forward<K>(key)];
-    }
-
     ~function_result() {
         stack::remove(L, index, popcount);
     }

sol/function_types_core.hpp

@@ -49,7 +49,7 @@ function_packer<Sig, Args...> function_pack( Args&&... args ) {
     return function_packer<Sig, Args...>(std::forward<Args>(args)...);
 }
 
-inline bool check_types(types<>, indices<>, lua_State* L, int) {
+inline bool check_types(types<>, indices<>, lua_State*, int) {
 	return true;
 }
 

sol/function_types_overload.hpp

@@ -37,7 +37,7 @@ struct overloaded_function : base_function {
 
     }
 
-    int match_arity(lua_State* L, std::ptrdiff_t x, indices<>) {
+    int match_arity(lua_State*, std::ptrdiff_t, indices<>) {
         throw error("no matching function call takes this number of arguments");
     }
 
@@ -99,7 +99,7 @@ struct usertype_overloaded_function : base_function {
 
     }
 
-    int match_arity(lua_State* L, std::ptrdiff_t x, indices<>) {
+    int match_arity(lua_State*, std::ptrdiff_t, indices<>) {
         throw error("no matching function call takes this number of arguments");
     }
 
@@ -154,7 +154,7 @@ struct usertype_indexing_function<overload_set<Functions...>, T> : base_function
     usertype_indexing_function(std::string name, Functions... fxs)
     : overloads({function_traits<Functions>::arity, fxs}...), name(std::move(name)) {}
 
-    int match_arity(lua_State* L, std::ptrdiff_t x, indices<>) {
+    int match_arity(lua_State*, std::ptrdiff_t, indices<>) {
         throw error("no matching function call takes this number of arguments");
     }
 

sol/function_types_static.hpp

@@ -75,7 +75,7 @@ struct static_member_function {
 
     template<typename... Ret, typename... Args>
     static int typed_call(types<Ret...> tr, types<Args...> ta, T& item, function_type& ifx, lua_State* L) {
-        auto fx = [&item, &ifx](Args&&... args) -> return_type { return (item.*ifx)(std::forward<Args>(args)...); };
+        auto fx = [&item, &ifx](Args&&... args) -> return_type_t<Ret...> { return (item.*ifx)(std::forward<Args>(args)...); };
         decltype(auto) r = stack::call(L, 0, tr, ta, fx);
         int nargs = static_cast<int>(sizeof...(Args));
         lua_pop(L, nargs);

sol/reference.hpp

@@ -40,7 +40,7 @@ struct push_pop<true, T> {
 template <bool top_level = false, typename T>
 push_pop<top_level, T> push_popper(T&& x) {
     return push_pop<top_level, T>(std::forward<T>(x));
-};
+}
 } // stack
 
 class reference {

sol/usertype.hpp

@@ -252,7 +252,8 @@ private:
     template<typename Fx>
     std::unique_ptr<base_function> make_function(const std::string&, Fx&& func) {
         typedef Unqualified<Fx> Fxu;
-        typedef Unqualified<std::remove_pointer_t<function_traits<Fxu>::arg<0>>> Argu;
+	   typedef std::tuple_element_t<0, typename function_traits<Fxu>::args_tuple_type> Arg0;
+        typedef Unqualified<std::remove_pointer_t<Arg0>> Argu;
         static_assert(std::is_base_of<Argu, T>::value, "Any non-member-function must have a first argument which is covariant with the desired usertype.");
         typedef std::decay_t<Fxu> function_type;
         return std::make_unique<usertype_function<function_type, T>>(func);

tests.cpp

@@ -85,7 +85,7 @@ struct self_test {
     }
 };
 
-int func_1(int a) {
+int func_1(int) {
     return 1;
 }
 
@@ -93,11 +93,11 @@ std::string func_1s(std::string a) {
     return "string: " + a;
 }
 
-int func_2(int a, int b) {
+int func_2(int, int) {
     return 2;
 }
 
-void func_3(int a, int b, int c) {
+void func_3(int, int, int) {
 
 }
 
@@ -1006,7 +1006,7 @@ TEST_CASE("references/get-set", "properly get and set with std::ref semantics. N
     REQUIRE(var.boop != my_var.boop);
     
     REQUIRE(std::addressof(ref_var) == std::addressof(rvar));
-    //REQUIRE(std::addressof(proxy_ref_var.get()) == std::addressof(rvar));
+    REQUIRE(std::addressof(proxy_ref_var.get()) == std::addressof(rvar));
     REQUIRE(rvar.boop == 5);
     REQUIRE(rvar.boop == ref_var.boop);
 }
@@ -1042,7 +1042,7 @@ TEST_CASE( "functions/function_result-protected_function", "Function result shou
         // Does not bypass error function, will call it
         luaL_error( lua.lua_state(), "BIG ERROR MESSAGES!" );
     };
-    auto specialhandler = []( std::string message ) {
+    auto specialhandler = []( std::string ) {
         return errormessage2;
     };