From 58ceecfe5ac0ad436d556b589870dd2df62731c0 Mon Sep 17 00:00:00 2001
From: Mark Dickinson <dickinsm@gmail.com>
Date: Sat, 20 Jul 2013 17:59:13 +0100
Subject: [PATCH] Issue #18513: Add workaround for OS X 10.8 cexp bug that
 leads to wrong cmath.rect(0.0,-0.0) results.

---
 Misc/NEWS             | 3 +++
 Modules/cmathmodule.c | 7 +++++++
 2 files changed, 10 insertions(+)

diff --git a/Misc/NEWS b/Misc/NEWS
index de16f7b1de8..f79f62584aa 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -49,6 +49,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #18513: Fix behaviour of cmath.rect w.r.t. signed zeros on OS X 10.8 +
+  gcc.
+
 - Issue #18480: Add missing call to PyType_Ready to the _elementtree extension.
 
 - Issue #17778: Fix test discovery for test_multiprocessing. (Patch by
diff --git a/Modules/cmathmodule.c b/Modules/cmathmodule.c
index 3021cf0466a..36bf4a1e3df 100644
--- a/Modules/cmathmodule.c
+++ b/Modules/cmathmodule.c
@@ -1006,6 +1006,13 @@ cmath_rect(PyObject *self, PyObject *args)
         else
             errno = 0;
     }
+    else if (phi == 0.0) {
+        /* Workaround for buggy results with phi=-0.0 on OS X 10.8.  See
+           bugs.python.org/issue18513. */
+        z.real = r;
+        z.imag = r * phi;
+        errno = 0;
+    }
     else {
         z.real = r * cos(phi);
         z.imag = r * sin(phi);