pythoncapi
diff --git a/‎Lib/test/test_complex.py‎
Lines changed: 23 additions & 0 deletions b/‎Lib/test/test_complex.py‎
Lines changed: 23 additions & 0 deletions
diff --git a/‎Misc/NEWS‎
Lines changed: 4 additions & 0 deletions b/‎Misc/NEWS‎
Lines changed: 4 additions & 0 deletions
diff --git a/‎Objects/complexobject.c‎
Lines changed: 3 additions & 3 deletions b/‎Objects/complexobject.c‎
Lines changed: 3 additions & 3 deletions
@@ -387,6 +387,29 @@ def __complex__(self):
         self.assertAlmostEqual(complex(complex1(1j)), 2j)
         self.assertRaises(TypeError, complex, complex2(1j))
 
+    @support.requires_IEEE_754
+    def test_constructor_special_numbers(self):
+        class complex2(complex):
+            pass
+        for x in 0.0, -0.0, INF, -INF, NAN:
+            for y in 0.0, -0.0, INF, -INF, NAN:
+                with self.subTest(x=x, y=y):
+                    z = complex(x, y)
+                    self.assertFloatsAreIdentical(z.real, x)
+                    self.assertFloatsAreIdentical(z.imag, y)
+                    z = complex2(x, y)
+                    self.assertIs(type(z), complex2)
+                    self.assertFloatsAreIdentical(z.real, x)
+                    self.assertFloatsAreIdentical(z.imag, y)
+                    z = complex(complex2(x, y))
+                    self.assertIs(type(z), complex)
+                    self.assertFloatsAreIdentical(z.real, x)
+                    self.assertFloatsAreIdentical(z.imag, y)
+                    z = complex2(complex(x, y))
+                    self.assertIs(type(z), complex2)
+                    self.assertFloatsAreIdentical(z.real, x)
+                    self.assertFloatsAreIdentical(z.imag, y)
+
     def test_underscores(self):
         # check underscores
         for lit in VALID_UNDERSCORE_LITERALS:
 
@@ -10,6 +10,10 @@ What's New in Python 3.7.0 alpha 1?
 Core and Builtins
 -----------------
 
+- bpo-29602: Fix incorrect handling of signed zeros in complex constructor for
+  complex subclasses and for inputs having a __complex__ method. Patch
+  by Serhiy Storchaka.
+
 - bpo-29347: Fixed possibly dereferencing undefined pointers
   when creating weakref objects.
 
 
@@ -1025,11 +1025,11 @@ complex_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
             return NULL;
         }
         cr.real = PyFloat_AsDouble(tmp);
-        cr.imag = 0.0; /* Shut up compiler warning */
+        cr.imag = 0.0;
         Py_DECREF(tmp);
     }
     if (i == NULL) {
-        ci.real = 0.0;
+        ci.real = cr.imag;
     }
     else if (PyComplex_Check(i)) {
         ci = ((PyComplexObject*)i)->cval;
@@ -1051,7 +1051,7 @@ complex_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
     if (ci_is_complex) {
         cr.real -= ci.imag;
     }
-    if (cr_is_complex) {
+    if (cr_is_complex && i != NULL) {
         ci.real += cr.imag;
     }
     return complex_subtype_from_doubles(type, cr.real, ci.real);
Original file line number	Diff line number	Diff line change
`@@ -1025,11 +1025,11 @@ complex_new(PyTypeObject type, PyObject args, PyObject *kwds)`
`1025`	`1025`	`return NULL;`
`1026`	`1026`	`}`
`1027`	`1027`	`cr.real = PyFloat_AsDouble(tmp);`
`1028`		`- cr.imag = 0.0; /* Shut up compiler warning */`
	`1028`	`+ cr.imag = 0.0;`
`1029`	`1029`	`Py_DECREF(tmp);`
`1030`	`1030`	`}`
`1031`	`1031`	`if (i == NULL) {`
`1032`		`- ci.real = 0.0;`
	`1032`	`+ ci.real = cr.imag;`
`1033`	`1033`	`}`
`1034`	`1034`	`else if (PyComplex_Check(i)) {`
`1035`	`1035`	`ci = ((PyComplexObject*)i)->cval;`
`@@ -1051,7 +1051,7 @@ complex_new(PyTypeObject type, PyObject args, PyObject *kwds)`
`1051`	`1051`	`if (ci_is_complex) {`
`1052`	`1052`	`cr.real -= ci.imag;`
`1053`	`1053`	`}`
`1054`		`- if (cr_is_complex) {`
	`1054`	`+ if (cr_is_complex && i != NULL) {`
`1055`	`1055`	`ci.real += cr.imag;`
`1056`	`1056`	`}`
`1057`	`1057`	`return complex_subtype_from_doubles(type, cr.real, ci.real);`