Patch LuaFunction memory leak

LuaCppInterface/luacppinterface.h

@@ -23,7 +23,10 @@ class Lua
 	template<typename SIG>
 	LuaFunction<SIG> internalCreateFunction( std::shared_ptr< std::function<SIG> > func, lua_CFunction cfunc)
 	{
-		LuaFunction<SIG>** ptr = (LuaFunction<SIG>**)lua_newuserdata(state.get(), sizeof(LuaFunction<SIG>**));
+		auto* ptr = (std::shared_ptr< std::function<SIG> >*)
+			lua_newuserdata(state.get(), sizeof(std::shared_ptr< std::function<SIG> >*));
+
+		ptr = new std::shared_ptr< std::function<SIG> >(func);
 
 		lua_newtable(state.get());
 
@@ -45,11 +48,8 @@ class Lua
 
 		// set the metatable
 		lua_setmetatable(state.get(), -2);
-		LuaFunction<SIG> function = LuaFunction<SIG>(state, -1, func);
 
-		// instantiate a luafunction that has a weak reference to the state
-		// that the lua garbage collector will collect.
-		*ptr = new LuaFunction<SIG>(LuaFunction<SIG>(LuaNoDestructor(state.get()), -1, func));
+		LuaFunction<SIG> function(LuaNoDestructor(state.get()), -1, func);
 
 		lua_pop(state.get(), 1);
 		return function;
@@ -58,8 +58,8 @@ class Lua
 	template<typename SIG>
 	static int lua_finalizer(lua_State* state)
 	{
-		LuaFunction<SIG>** func = (LuaFunction<SIG>**)lua_touserdata(state, lua_upvalueindex(1));
-		delete *func;
+		auto* func = (std::shared_ptr< std::function<SIG> >*)lua_touserdata(state, lua_upvalueindex(1));
+		delete func;
 		return 0;
 	};
 

tests/Makefile.am

@@ -3,7 +3,7 @@ if COND_GCOV
    MAYBE_COVERAGE=-fprofile-arcs
 endif
 
-TESTS = demonstration1 demonstration2 demonstration3 demonstration4 luacpp testcallabletable testchartowideconvert testcoroutineexception testcoroutineexpectedbutnot testcreate testctoluafunction testexceptioninluafunction testextractingasfunctionbutistable testfunction testfunctionerror testfunctionexpectedbutnotcallable testfunctionparams testfunctionparamsreturn testfunctionreturn testgetmetatableonclosedstate testgetsetfunction testgetsetfunction2 testgetsetinsidetable testgetsetinteger testgetsetstring testgetsettable testgetstate testgettypeofvalueat testinvalidscript testpassingfunction testreadinglightuserdatafromuserdata testregistry testresumenoscript testreturnfromnative testreturnfromscript testreturnfromyieldingfunction testreturntablefromlua testreturntablefromnative testscriptexception testsetstring testsetwstring testtable testtableexpectedbutnotable testtableforeachintegerkey testtableforeachstringkey testtypeintstringmorph testtypemorphintwstring testtypestringintmorph testuserdata testuserdataconstructor testuserdatadispose testuserdatamethod testwidetocharconvert
+TESTS = demonstration1 demonstration2 demonstration3 demonstration4 luacpp testcallabletable testchartowideconvert testcoroutineexception testcoroutineexpectedbutnot testcreate testctoluafunction testexceptioninluafunction testextractingasfunctionbutistable testfunction testfunctiondoesntleak testfunctionerror testfunctionexpectedbutnotcallable testfunctionparams testfunctionparamsreturn testfunctionreturn testgetmetatableonclosedstate testgetsetfunction testgetsetfunction2 testgetsetinsidetable testgetsetinteger testgetsetstring testgetsettable testgetstate testgettypeofvalueat testinvalidscript testpassingfunction testreadinglightuserdatafromuserdata testregistry testresumenoscript testreturnfromnative testreturnfromscript testreturnfromyieldingfunction testreturntablefromlua testreturntablefromnative testscriptexception testsetstring testsetwstring testtable testtableexpectedbutnotable testtableforeachintegerkey testtableforeachstringkey testtypeintstringmorph testtypemorphintwstring testtypestringintmorph testuserdata testuserdataconstructor testuserdatadispose testuserdatamethod testwidetocharconvert
 
 check_PROGRAMS = $(TESTS)
 
@@ -53,6 +53,9 @@ testextractingasfunctionbutistable_LDADD = $(REQUIRED_LIBS)
 testfunction_SOURCES = testfunction.cpp lua
 testfunction_LDADD = $(REQUIRED_LIBS)
 
+testfunctiondoesntleak_SOURCES = testfunctiondoesntleak.cpp lua
+testfunctiondoesntleak_LDADD = $(REQUIRED_LIBS)
+
 testfunctionerror_SOURCES = testfunctionerror.cpp lua
 testfunctionerror_LDADD = $(REQUIRED_LIBS)
 

tests/testfunctiondoesntleak.cpp

@@ -0,0 +1,31 @@
+// Test for CreateFunction memory leak
+
+#include <memory>
+#include <luacppinterface.h>
+
+struct Functor {
+	std::shared_ptr<int> ptr;
+
+	void operator()() const {
+		// no-op
+	}
+};
+
+int main()
+{
+	Lua lua;
+
+	// Create a LuaFunction from a functor that holds a shared_ptr to
+	// a resource. If the function created via CreateFunction gets
+	// collected by the GC, the weak pointer will expire after that
+	std::weak_ptr<int> weak;
+	{
+		auto ptr = std::make_shared<int>(0);
+		weak = ptr;
+		auto function = lua.CreateFunction<void()>(Functor{ptr});
+	}
+
+	lua.CollectGarbage();
+
+	return !weak.expired();
+}