Disallow requiring love.graphics and love.window in threads.

src/common/runtime.cpp

@@ -1064,6 +1064,13 @@ lua_State *luax_getpinnedthread(lua_State *L)
 	return thread;
 }
 
+extern "C" int luax_module_threaderror(lua_State *L)
+{
+	// Module name is the first param in the stack.
+	const char *name = luaL_checkstring(L, 1);
+	return luaL_error(L, "The %s module cannot be used in thread code.", name);
+}
+
 void luax_markdeprecated(lua_State *L, int level, const char *name, APIType api)
 {
 	luax_markdeprecated(L, level, name, api, DEPRECATED_NO_REPLACEMENT, nullptr);

src/common/runtime.h

@@ -493,6 +493,14 @@ lua_State *luax_insistpinnedthread(lua_State *L);
  **/
 lua_State *luax_getpinnedthread(lua_State *L);
 
+/**
+ * Lua C function to use with luax_preload when the given module should not
+ * be allowed on a thread. Must be called from the thread's code.
+ **/
+extern "C" {
+	int luax_module_threaderror(lua_State *L);
+}
+
 /**
  * Mark a function as deprecated. Should only be called inside wrapper function
  * code.

src/modules/thread/LuaThread.cpp

@@ -68,6 +68,10 @@ void LuaThread::threadFunction()
 	lua_pop(L, 1);
 #endif // LOVE_BUILD_STANDALONE
 
+	// We might want to add more input-related modules to this list.
+	luax_preload(L, luax_module_threaderror, "love.window");
+	luax_preload(L, luax_module_threaderror, "love.graphics");
+
 	luax_require(L, "love.thread");
 	lua_pop(L, 1);