fixup value on win32

Author: skirpichev

Lib/test/test_capi/test_float.py

@@ -183,25 +183,27 @@ def test_pack_unpack_roundtrip(self):
     def test_pack_unpack_roundtrip_for_nans(self):
         pack = _testcapi.float_pack
         unpack = _testcapi.float_unpack
-
-        for _ in range(100):
+        for _ in range(1000):
             for size in (2, 4, 8):
                 sign = random.randint(0, 1)
-                quiet = random.randint(0, 1)
+                signaling = random.randint(0, 1)
+                quiet = int(not signaling)
                 if size == 8:
-                    payload = random.randint(0 if quiet else 1, 1<<50)
+                    payload = random.randint(signaling, 1<<50)
                     i = (sign<<63) + (0x7ff<<52) + (quiet<<51) + payload
                 elif size == 4:
-                    payload = random.randint(0 if quiet else 1, 1<<21)
+                    payload = random.randint(signaling, 1<<21)
                     i = (sign<<31) + (0xff<<23) + (quiet<<22) + payload
                 elif size == 2:
-                    payload = random.randint(0 if quiet else 1, 1<<8)
+                    payload = random.randint(signaling, 1<<8)
                     i = (sign<<15) + (0x1f<<10) + (quiet<<9) + payload
                 data = bytes.fromhex(f'{i:x}')
                 for endian in (BIG_ENDIAN, LITTLE_ENDIAN):
                     with self.subTest(data=data, size=size, endian=endian):
                         data1 = data if endian == BIG_ENDIAN else data[::-1]
                         value = unpack(data1, endian)
+                        if signaling and sys.platform == 'win32':
+                            value = _testcapi.float_set_snan(value)
                         data2 = pack(size, value, endian)
                         self.assertTrue(math.isnan(value))
                         self.assertEqual(data1, data2)

Modules/_testcapi/clinic/float.c.h

@@ -157,13 +157,46 @@ test_string_to_double(PyObject *self, PyObject *Py_UNUSED(ignored))
 }
 
 
+/*[clinic input]
+_testcapi.float_set_snan
+
+    obj: object
+    /
+
+Make a signaling NaN.
+[clinic start generated code]*/
+
+static PyObject *
+_testcapi_float_set_snan(PyObject *module, PyObject *obj)
+/*[clinic end generated code: output=f43778a70f60aa4b input=c1269b0f88ef27ac]*/
+{
+    if (!PyFloat_Check(obj)) {
+        PyErr_SetString(PyExc_ValueError, "float-point number expected");
+        return NULL;
+    }
+    PyObject *ret = PyNumber_Positive(obj);
+    if (!ret) {
+        return NULL;
+    }
+    double *d = &((PyFloatObject *)ret)->ob_fval;
+    if (!isnan(*d)) {
+        PyErr_SetString(PyExc_ValueError, "nan expected");
+        return NULL;
+    }
+    uint64_t *v = (uint64_t *)d;
+    *v &= ~(1ULL<<51); /* make sNaN */
+    return ret;
+}
+
 static PyMethodDef test_methods[] = {
     _TESTCAPI_FLOAT_PACK_METHODDEF
     _TESTCAPI_FLOAT_UNPACK_METHODDEF
+    _TESTCAPI_FLOAT_SET_SNAN_METHODDEF
     {"test_string_to_double", test_string_to_double, METH_NOARGS},
     {NULL},
 };
 
+
 int
 _PyTestCapi_Init_Float(PyObject *mod)
 {