MAINT: Fix pickling/unpickling for unsigned flags

seberg · seberg · commit 237524d2c722 · 2024-03-05T14:47:06.000+01:00
Note that the (rare) aligned struct case will not allow unpickling
NumPy 2.x files with NumPy 1.x.  This could be added if necessary.

Unpickling 1.x files in 2.x is unproblematic
diff --git a/numpy/_core/src/multiarray/descriptor.c b/numpy/_core/src/multiarray/descriptor.c
@@ -2785,7 +2785,7 @@ arraydescr_reduce(PyArray_Descr *self, PyObject *NPY_UNUSED(args))
     }
     PyTuple_SET_ITEM(state, 5, PyLong_FromLong(elsize));
     PyTuple_SET_ITEM(state, 6, PyLong_FromLong(alignment));
-    PyTuple_SET_ITEM(state, 7, PyLong_FromLong(self->flags));
+    PyTuple_SET_ITEM(state, 7, PyLong_FromUnsignedLongLong(self->flags));
 
     PyTuple_SET_ITEM(ret, 2, state);
     return ret;
@@ -2840,7 +2840,7 @@ arraydescr_setstate(_PyArray_LegacyDescr *self, PyObject *args)
     PyObject *subarray, *fields, *names = NULL, *metadata=NULL;
     int incref_names = 1;
     int int_dtypeflags = 0;
-    char dtypeflags;
+    npy_uint64 dtypeflags;
 
     if (!PyDataType_ISLEGACY(self)) {
         PyErr_SetString(PyExc_RuntimeError,
@@ -3140,6 +3140,10 @@ arraydescr_setstate(_PyArray_LegacyDescr *self, PyObject *args)
      * flags as an int even though it actually was a char in the PyArray_Descr
      * structure
      */
+    if (int_dtypeflags < 0 && int_dtypeflags >= -128) {
+        /* NumPy used to use a char. So normalize if signed. */
+        int_dtypeflags += 128;
+    }
     dtypeflags = int_dtypeflags;
     if (dtypeflags != int_dtypeflags) {
         PyErr_Format(PyExc_ValueError,
