Function _convert_from_list

numpy/core/src/multiarray/descriptor.c:611–710

* a list specifying a data-type can just be * a list of formats. The names for the fields * will default to f0, f1, f2, and so forth. */

 * will default to f0, f1, f2, and so forth.
 */
static PyArray_Descr *
_convert_from_list(PyObject *obj, int align)
{
    int n = PyList_GET_SIZE(obj);
    /*
     * Ignore any empty string at end which _internal._commastring
     * can produce
     */
    PyObject *last_item = PyList_GET_ITEM(obj, n-1);
    if (PyUnicode_Check(last_item)) {
        Py_ssize_t s = PySequence_Size(last_item);
        if (s < 0) {
            return NULL;
        }
        if (s == 0) {
            n = n - 1;
        }
    }
    if (n == 0) {
        PyErr_SetString(PyExc_ValueError, "Expected at least one field name");
        return NULL;
    }
    PyObject *nameslist = PyTuple_New(n);
    if (!nameslist) {
        return NULL;
    }
    PyObject *fields = PyDict_New();
    if (!fields) {
        Py_DECREF(nameslist);
        return NULL;
    }

    /* Types with fields need the Python C API for field access */
    char dtypeflags = NPY_NEEDS_PYAPI;
    int maxalign = 0;
    int totalsize = 0;
    for (int i = 0; i < n; i++) {
        PyArray_Descr *conv = _convert_from_any(
                PyList_GET_ITEM(obj, i), align);
        if (conv == NULL) {
            goto fail;
        }
        dtypeflags |= (conv->flags & NPY_FROM_FIELDS);
        if (align) {
            int _align = conv->alignment;
            if (_align > 1) {
                totalsize = NPY_NEXT_ALIGNED_OFFSET(totalsize, _align);
            }
            maxalign = PyArray_MAX(maxalign, _align);
        }
        PyObject *size_obj = PyLong_FromLong((long) totalsize);
        if (!size_obj) {
            Py_DECREF(conv);
            goto fail;
        }
        PyObject *tup = PyTuple_New(2);
        if (!tup) {
            Py_DECREF(size_obj);