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[3.6] bpo-31373: remove overly strict float range checks (GH-3486) by benjaminp · Pull Request #3495 · python/cpython

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[3.6] bpo-31373: remove overly strict float range checks (GH-3486) #3495

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6 changes: 6 additions & 0 deletions Lib/test/test_float.py

Original file line number Diff line number Diff line change
Expand Up @@ -613,6 +613,12 @@ def test_float_specials_do_unpack(self):
('<f', LE_FLOAT_NAN)]:
struct.unpack(fmt, data)

@support.requires_IEEE_754
def test_serialized_float_rounding(self):
from _testcapi import FLT_MAX
self.assertEqual(struct.pack("<f", 3.40282356e38), struct.pack("<f", FLT_MAX))
self.assertEqual(struct.pack("<f", -3.40282356e38), struct.pack("<f", -FLT_MAX))

class FormatTestCase(unittest.TestCase):

def test_format(self):
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6 changes: 6 additions & 0 deletions Lib/test/test_getargs2.py

Original file line number Diff line number Diff line change
Expand Up @@ -377,6 +377,12 @@ def test_f(self):
r = getargs_f(NAN)
self.assertNotEqual(r, r)

@support.requires_IEEE_754
def test_f_rounding(self):
from _testcapi import getargs_f
self.assertEqual(getargs_f(3.40282356e38), FLT_MAX)
self.assertEqual(getargs_f(-3.40282356e38), -FLT_MAX)

def test_d(self):
from _testcapi import getargs_d
self.assertEqual(getargs_d(4.25), 4.25)
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4 changes: 2 additions & 2 deletions Objects/floatobject.c

Original file line number Diff line number Diff line change
Expand Up @@ -2182,13 +2182,13 @@ _PyFloat_Pack4(double x, unsigned char *p, int le)

}
else {
float y = (float)x;
int i, incr = 1;

if (fabs(x) > FLT_MAX && !Py_IS_INFINITY(x))
if (Py_IS_INFINITY(y) && !Py_IS_INFINITY(x))
goto Overflow;

unsigned char s[sizeof(float)];
float y = (float)x;
memcpy(s, &y, sizeof(float));

if ((float_format == ieee_little_endian_format && !le)
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4 changes: 0 additions & 4 deletions Python/getargs.c

Original file line number Diff line number Diff line change
Expand Up @@ -811,10 +811,6 @@ convertsimple(PyObject *arg, const char **p_format, va_list *p_va, int flags,
double dval = PyFloat_AsDouble(arg);
if (PyErr_Occurred())
RETURN_ERR_OCCURRED;
else if (dval > FLT_MAX)
*p = (float)INFINITY;
else if (dval < -FLT_MAX)
*p = (float)-INFINITY;
else
*p = (float) dval;
break;
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