[BUG] clang warning from View.MemoryView's array_cwrapper

[wkschwartz]

Describe the bug

Cythonizing and compiling on macOS with Apple clang version 14.0.3 (clang-1403.0.22.14.1) generates the following

compiler warning for "equality comparison with extraneous parentheses".

clang -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -isysroot $MACOS13SDK -I$VENV_INCLUDE -I$PYTHON311_INCLUDE -c mycode.c -o $BUILD_DIR/mycode.o
mycode.c:5898:28: warning: equality comparison with extraneous parentheses
      [-Wparentheses-equality]
  if (((__pyx_v_c_mode[0]) == 'f')) {
       ~~~~~~~~~~~~~~~~~~~~^~~~~~
mycode.c:5898:28: note: remove extraneous parentheses around the comparison to
      silence this warning
  if (((__pyx_v_c_mode[0]) == 'f')) {
      ~                    ^     ~
mycode.c:5898:28: note: use '=' to turn this equality comparison into an
      assignment
  if (((__pyx_v_c_mode[0]) == 'f')) {
                           ^~
                           =
1 warning generated.

Searching mycode.c for if (((__pyx_v_c_mode[0]) == 'f')) { takes me to the following

generated C function.

/* "View.MemoryView":268
 * 
 * @cname("__pyx_array_new")
 * cdef array array_cwrapper(tuple shape, Py_ssize_t itemsize, char *format, char *c_mode, char *buf):             # <<<<<<<<<<<<<<
 *     cdef array result
 *     cdef str mode = "fortran" if c_mode[0] == b'f' else "c"  # this often comes from a constant C string.
 */

static struct __pyx_array_obj *__pyx_array_new(PyObject *__pyx_v_shape, Py_ssize_t __pyx_v_itemsize, char *__pyx_v_format, char *__pyx_v_c_mode, char *__pyx_v_buf) {
  struct __pyx_array_obj *__pyx_v_result = 0;
  PyObject *__pyx_v_mode = 0;
  struct __pyx_array_obj *__pyx_r = NULL;
  __Pyx_RefNannyDeclarations
  PyObject *__pyx_t_1 = NULL;
  int __pyx_t_2;
  PyObject *__pyx_t_3 = NULL;
  PyObject *__pyx_t_4 = NULL;
  int __pyx_lineno = 0;
  const char *__pyx_filename = NULL;
  int __pyx_clineno = 0;
  __Pyx_RefNannySetupContext("array_cwrapper", 0);

  /* "View.MemoryView":270
 * cdef array array_cwrapper(tuple shape, Py_ssize_t itemsize, char *format, char *c_mode, char *buf):
 *     cdef array result
 *     cdef str mode = "fortran" if c_mode[0] == b'f' else "c"  # this often comes from a constant C string.             # <<<<<<<<<<<<<<
 * 
 *     if buf is NULL:
 */
  if (((__pyx_v_c_mode[0]) == 'f')) {
    __Pyx_INCREF(__pyx_n_s_fortran);
    __pyx_t_1 = __pyx_n_s_fortran;
  } else {
    __Pyx_INCREF(__pyx_n_s_c);
    __pyx_t_1 = __pyx_n_s_c;
  }
  __pyx_v_mode = ((PyObject*)__pyx_t_1);
  __pyx_t_1 = 0;

/* ✂️ */
}

Code to reproduce the behaviour:

I don't have a minimal example, except to say that my code uses Cython memoryviews extensively as function parameters like unsigned int8_t[:, :, ::1] out not None. I build my Cython code with the following setup.py

from setuptools import setup
from Cython.Build import cythonize
setup(ext_modules=cythonize('mycode.pyx'))

and then I ran

$ python setup.py build_ext --force --inplace

Expected behaviour

Cython's generated C code should not produce warnings on major compilers under default build setups.

OS

macOS 13.4.1

Python version

CPython 3.11.3

Cython version

3.0.0

Additional context

setuptools 67.7.2

$ clang --version
Apple clang version 14.0.3 (clang-1403.0.22.14.1)
Target: x86_64-apple-darwin22.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin