Fix complex add/sub handling of negative zero

Fixes #585

Author: msimacek

graalpython/com.oracle.graal.python.test/src/tests/test_complex.py

@@ -39,6 +39,7 @@
 import sys
 import unittest
 from math import atan2
+import math
 
 def test_create():
     c = 4 + 4j
@@ -91,6 +92,46 @@ def test_sub():
     assert (1.5 - c2) == complex(-0.5, -2)
 
 
+def test_mixed_real_complex_zero_signs():
+    z = complex(0.0, -0.0)
+
+    def add_int_local():
+        x = 0
+        return z + x, x + z
+
+    def add_float_local():
+        x = 0.0
+        return z + x, x + z
+
+    def add_bool_local():
+        x = False
+        return z + x, x + z
+
+    for left, right in (add_int_local(), add_float_local(), add_bool_local()):
+        assert left == right
+        assert math.copysign(1.0, left.imag) == 1.0
+        assert math.copysign(1.0, right.imag) == 1.0
+
+    def sub_int_local():
+        x = 0
+        return x - z, z - x
+
+    def sub_float_local():
+        x = 0.0
+        return x - z, z - x
+
+    def sub_bool_local():
+        x = False
+        return x - z, z - x
+
+    # Subtraction is not commutative, but sign handling should follow CPython.
+    for left, right in (sub_int_local(), sub_float_local(), sub_bool_local()):
+        assert left == 0j
+        assert right == -0j
+        assert math.copysign(1.0, left.imag) == 1.0
+        assert math.copysign(1.0, right.imag) == -1.0
+
+
 def test_div():
     c2 = 2+2j
     assert (c2 / 2) == complex(1, 1)

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/complex/ComplexBuiltins.java

@@ -966,13 +966,25 @@ abstract static class AddNode extends BinaryOpBuiltinNode {
         @Specialization
         static PComplex doInt(PComplex left, int right,
                         @Bind PythonLanguage language) {
-            return PFactory.createComplex(language, left.getReal() + right, left.getImag());
+            return PFactory.createComplex(language, left.getReal() + right, left.getImag() + 0.0);
         }
 
         @Specialization
         static PComplex doDouble(PComplex left, double right,
                         @Bind PythonLanguage language) {
-            return PFactory.createComplex(language, left.getReal() + right, left.getImag());
+            return PFactory.createComplex(language, left.getReal() + right, left.getImag() + 0.0);
+        }
+
+        @Specialization
+        static PComplex doInt(int left, PComplex right,
+                        @Bind PythonLanguage language) {
+            return PFactory.createComplex(language, left + right.getReal(), 0.0 + right.getImag());
+        }
+
+        @Specialization
+        static PComplex doDouble(double left, PComplex right,
+                        @Bind PythonLanguage language) {
+            return PFactory.createComplex(language, left + right.getReal(), 0.0 + right.getImag());
         }
 
         @Specialization
@@ -1082,13 +1094,25 @@ static ComplexValue multiply(ComplexValue left, ComplexValue right) {
     abstract static class SubNode extends BinaryOpBuiltinNode {
         static PComplex doComplex(PComplex left, double right,
                         @Bind PythonLanguage language) {
-            return PFactory.createComplex(language, left.getReal() - right, left.getImag());
+            return PFactory.createComplex(language, left.getReal() - right, left.getImag() - 0.0);
         }
 
         @Specialization
         static PComplex doComplex(PComplex left, int right,
                         @Bind PythonLanguage language) {
-            return PFactory.createComplex(language, left.getReal() - right, left.getImag());
+            return PFactory.createComplex(language, left.getReal() - right, left.getImag() - 0.0);
+        }
+
+        @Specialization
+        static PComplex doComplex(int left, PComplex right,
+                        @Bind PythonLanguage language) {
+            return PFactory.createComplex(language, left - right.getReal(), 0.0 - right.getImag());
+        }
+
+        @Specialization
+        static PComplex doComplex(double left, PComplex right,
+                        @Bind PythonLanguage language) {
+            return PFactory.createComplex(language, left - right.getReal(), 0.0 - right.getImag());
         }
 
         @Specialization