Index: Lib/test/test_math.py
===================================================================
--- Lib/test/test_math.py	(révision 86282)
+++ Lib/test/test_math.py	(copie de travail)
@@ -8,6 +8,7 @@
 import sys
 import random
 import struct
+import sysconfig

 eps = 1E-05
 NAN = float('nan')
@@ -891,11 +892,16 @@
         self.ftest('tanh(inf)', math.tanh(INF), 1)
         self.ftest('tanh(-inf)', math.tanh(NINF), -1)
         self.assertTrue(math.isnan(math.tanh(NAN)))
+
+    @unittest.skipUnless(float.__getformat__("double").startswith("IEEE"),
+                         'need IEEE double float')
+    @unittest.skipIf(sysconfig.get_config_var('TANH_PRESERVES_ZERO_SIGN') == 0,
+                     "system tanh() function doesn't copy the sign")
+    def testTanhSign(self):
         # check that tanh(-0.) == -0. on IEEE 754 systems
-        if float.__getformat__("double").startswith("IEEE"):
-            self.assertEqual(math.tanh(-0.), -0.)
-            self.assertEqual(math.copysign(1., math.tanh(-0.)),
-                             math.copysign(1., -0.))
+        self.assertEqual(math.tanh(-0.), -0.)
+        self.assertEqual(math.copysign(1., math.tanh(-0.)),
+                         math.copysign(1., -0.))

     def test_trunc(self):
         self.assertEqual(math.trunc(1), 1)
Index: Lib/test/test_cmath.py
===================================================================
--- Lib/test/test_cmath.py	(révision 86282)
+++ Lib/test/test_cmath.py	(copie de travail)
@@ -3,6 +3,7 @@
 import unittest
 import cmath, math
 from cmath import phase, polar, rect, pi
+import sysconfig

 INF = float('inf')
 NAN = float('nan')
@@ -61,6 +62,11 @@
     def tearDown(self):
         self.test_values.close()

+    def assertComplexEqual(self, a, b):
+        self.assertEqual(a, b)
+        self.assertEqual(math.copysign(1., a.real), math.copysign(1., b.real))
+        self.assertEqual(math.copysign(1., a.imag), math.copysign(1., b.imag))
+
     def rAssertAlmostEqual(self, a, b, rel_err = 2e-15, abs_err = 5e-323,
                            msg=None):
         """Fail if the two floating-point numbers are not almost equal.
@@ -473,7 +479,15 @@
         self.assertTrue(cmath.isinf(complex(NAN, INF)))
         self.assertTrue(cmath.isinf(complex(INF, NAN)))

+    @unittest.skipIf(sysconfig.get_config_var('TANH_PRESERVES_ZERO_SIGN') == 0,
+                     "system tanh() function doesn't copy the sign")
+    def testTanhSign(self):
+        self.assertComplexEqual(cmath.tanh(complex(0., .0j)), complex(0., .0j))
+        self.assertComplexEqual(cmath.tanh(complex(0., -.0j)), complex(0., -.0j))
+        self.assertComplexEqual(cmath.tanh(complex(-0., .0j)), complex(-0., .0j))
+        self.assertComplexEqual(cmath.tanh(complex(-0., -.0j)), complex(-0., -.0j))

+
 def test_main():
     run_unittest(CMathTests)

Index: Lib/test/cmath_testcases.txt
===================================================================
--- Lib/test/cmath_testcases.txt	(révision 86282)
+++ Lib/test/cmath_testcases.txt	(copie de travail)
@@ -1858,12 +1858,6 @@
 -- tanh: Hyperbolic Tangent --
 ------------------------------

--- zeros
-tanh0000 tanh 0.0 0.0 -> 0.0 0.0
-tanh0001 tanh 0.0 -0.0 -> 0.0 -0.0
-tanh0002 tanh -0.0 0.0 -> -0.0 0.0
-tanh0003 tanh -0.0 -0.0 -> -0.0 -0.0
-
 -- random inputs
 tanh0004 tanh -21.200500450664993 -1.6970729480342996 -> -1.0 1.9241352344849399e-19
 tanh0005 tanh -0.34158771504251928 -8.0848504951747131 -> -2.123711225855613 1.2827526782026006