Take lua_Destructor in lua_newuserdatadtor (with lua_State argument).

mlua needs access to Lua state in userdata destructor to set a flag
to prevent further access to Lua VM ops in destructor.

Author: khvzak

CLI/src/Repl.cpp

@@ -169,7 +169,7 @@ void* createCliRequireContext(lua_State* L)
     void* ctx = lua_newuserdatadtor(
         L,
         sizeof(ReplRequirer),
-        [](void* ptr)
+        [](lua_State*, void* ptr)
         {
             static_cast<ReplRequirer*>(ptr)->~ReplRequirer();
         }

VM/include/lua.h

@@ -54,6 +54,12 @@ typedef int (*lua_Continuation)(lua_State* L, int status);
 
 typedef void* (*lua_Alloc)(void* ud, void* ptr, size_t osize, size_t nsize);
 
+/*
+** prototype for userdata destructor
+*/
+
+typedef void (*lua_Destructor)(lua_State* L, void* userdata);
+
 // non-return type
 #define l_noret void LUA_NORETURN
 
@@ -189,7 +195,7 @@ LUA_API int lua_pushthread(lua_State* L);
 LUA_API void lua_pushlightuserdatatagged(lua_State* L, void* p, int tag);
 LUA_API void* lua_newuserdatatagged(lua_State* L, size_t sz, int tag);
 LUA_API void* lua_newuserdatataggedwithmetatable(lua_State* L, size_t sz, int tag); // metatable fetched with lua_getuserdatametatable
-LUA_API void* lua_newuserdatadtor(lua_State* L, size_t sz, void (*dtor)(void*));
+LUA_API void* lua_newuserdatadtor(lua_State* L, size_t sz, lua_Destructor dtor);
 
 LUA_API void* lua_newbuffer(lua_State* L, size_t sz);
 
@@ -319,8 +325,6 @@ LUA_API double lua_clock();
 
 LUA_API void lua_setuserdatatag(lua_State* L, int idx, int tag);
 
-typedef void (*lua_Destructor)(lua_State* L, void* userdata);
-
 LUA_API void lua_setuserdatadtor(lua_State* L, int tag, lua_Destructor dtor);
 LUA_API lua_Destructor lua_getuserdatadtor(lua_State* L, int tag);
 

VM/src/lapi.cpp

@@ -1326,7 +1326,7 @@ void* lua_newuserdatataggedwithmetatable(lua_State* L, size_t sz, int tag)
     return u->data;
 }
 
-void* lua_newuserdatadtor(lua_State* L, size_t sz, void (*dtor)(void*))
+void* lua_newuserdatadtor(lua_State* L, size_t sz, lua_Destructor dtor)
 {
     luaC_checkGC(L);
     luaC_threadbarrier(L);

VM/src/ludata.cpp

@@ -32,10 +32,10 @@ void luaU_freeudata(lua_State* L, Udata* u, lua_Page* page)
     }
     else if (u->tag == UTAG_IDTOR)
     {
-        void (*dtor)(void*) = nullptr;
+        lua_Destructor dtor = nullptr;
         memcpy(&dtor, &u->data + u->len - sizeof(dtor), sizeof(dtor));
         if (dtor)
-            dtor(u->data);
+            dtor(L, u->data);
     }
 
 

tests/Conformance.test.cpp

@@ -1605,15 +1605,15 @@ TEST_CASE("Reference")
     lua_newuserdatadtor(
         L,
         0,
-        [](void*)
+        [](lua_State*, void* data)
         {
             dtorhits++;
         }
     );
     lua_newuserdatadtor(
         L,
         0,
-        [](void*)
+        [](lua_State*, void* data)
         {
             dtorhits++;
         }
@@ -1651,7 +1651,7 @@ TEST_CASE("NewUserdataOverflow")
         [](lua_State* L1)
         {
             // The following userdata request might cause an overflow.
-            lua_newuserdatadtor(L1, SIZE_MAX, [](void* d) {});
+            lua_newuserdatadtor(L1, SIZE_MAX, [](lua_State*, void* d) {});
             // The overflow might segfault in the following call.
             lua_getmetatable(L1, -1);
             return 0;
@@ -2557,7 +2557,7 @@ TEST_CASE("UserdataApi")
     void* ud3 = lua_newuserdatadtor(
         L,
         4,
-        [](void* data)
+        [](lua_State*, void* data)
         {
             dtorhits += *(int*)data;
         }
@@ -2566,7 +2566,7 @@ TEST_CASE("UserdataApi")
     void* ud4 = lua_newuserdatadtor(
         L,
         1,
-        [](void* data)
+        [](lua_State*, void* data)
         {
             dtorhits += *(char*)data;
         }
@@ -2646,7 +2646,7 @@ TEST_CASE("UserdataAlignment")
 
         for (int i = 0; i < 10; i++)
         {
-            void* data = lua_newuserdatadtor(L, size, [](void*) {});
+            void* data = lua_newuserdatadtor(L, size, [](lua_State*, void* data) {});
             LUAU_ASSERT(uintptr_t(data) % 16 == 0);
             lua_pop(L, 1);
         }