What is causing SWIG to generate invalid code?

I have been interfacing between Python and C using ctypes, and I have been trying to switch to using SWIG. However, the code generated by SWIG has errors and will not compile.

I have two .c files UTTT.c and UTTT_Library.c, a header file for both of the files, boardCount.h, and the interface file UTTT.i. I am using Windows Subsystem for Linux

After running swig -python UTTT.i and gcc -c -fpic UTTT_wrap.c UTTT.c UTTT_Library.c -I/usr/local/include/python3.12 I get a compilation error in the code generated by SWIG:

UTTT_wrap.c: In function ‘_wrap_CGameState_board_set’:UTTT_wrap.c:3555:60: error: assignment to expression with array type           for (; jj < (size_t)3; ++jj) arg1->board[ii][jj] = arg2[ii][jj];

I am unsure exactly what the issue with the array assignment is, but I am also confused why SWIG is not generating valid code.

Here is the contents of UTTT.i

%module UTTT%{    #include "boardCount.h"%}%include boardCount.h

This is what setup.py contains:

#!/usr/bin/env python3from distutils.core import setup, Extensionexample_module = Extension('_UTTT',sources = ['UTTT_wrap.cxx', 'UTTT_Library.c', "UTTT.c"])setup (name = 'UTTT',       version = '0.1',       author      = "Robert Stegmann",       description = """Library for ultimate tic tac toe""",       ext_modules = [example_module],       py_modules = ["UTTT"],       )

Here is an excerpt from boardCount.h defining CGameState

#define ROW_DIMENSION 3#define COL_DIMENSION ROW_DIMENSIONtypedef struct {    char board[9][ROW_DIMENSION][COL_DIMENSION];    char boardsWon[ROW_DIMENSION][COL_DIMENSION];    unsigned char currentBoard;    unsigned char currentTurn;    char gameWon;} CGameState;

Here is the code generated by SWIG that has the issue

SWIGINTERN PyObject *_wrap_CGameState_board_set(PyObject *SWIGUNUSEDPARM(self), PyObject *args) {  PyObject *resultobj = 0;  CGameState *arg1 = (CGameState *) 0 ;  char (*arg2)[3][3] ;  void *argp1 = 0 ;  int res1 = 0 ;  void *argp2 = 0 ;  int res2 = 0 ;  PyObject * obj0 = 0 ;  PyObject * obj1 = 0 ;  if (!PyArg_ParseTuple(args,(char *)"OO:CGameState_board_set",&obj0,&obj1)) SWIG_fail;  res1 = SWIG_ConvertPtr(obj0, &argp1,SWIGTYPE_p_CGameState, 0 |  0 );  if (!SWIG_IsOK(res1)) {    SWIG_exception_fail(SWIG_ArgError(res1), "in method '" "CGameState_board_set" "', argument " "1"" of type '" "CGameState *""'");   }  arg1 = (CGameState *)(argp1);  res2 = SWIG_ConvertPtr(obj1, &argp2,SWIGTYPE_p_a_3__a_3__char, 0 |  0 );  if (!SWIG_IsOK(res2)) {    SWIG_exception_fail(SWIG_ArgError(res2), "in method '" "CGameState_board_set" "', argument " "2"" of type '" "char [9][3][3]""'");   }   arg2 = (char (*)[3][3])(argp2);  {    if (arg2) {      size_t ii = 0;      for (; ii < (size_t)9; ++ii) {        if (arg2[ii]) {          size_t jj = 0;          for (; jj < (size_t)3; ++jj) arg1->board[ii][jj] = arg2[ii][jj];        } else {          SWIG_exception_fail(SWIG_ValueError, "invalid null reference " "in variable '""board""' of type '""char [9][3][3]""'");        }      }    } else {      SWIG_exception_fail(SWIG_ValueError, "invalid null reference " "in variable '""board""' of type '""char [9][3][3]""'");    }  }  resultobj = SWIG_Py_Void();  return resultobj;fail:  return NULL;}