Merge pull request RustPython#1123 from corona10/fix_complex_hash

windelbouwman · web-flow · commit dd20263fba8d · 2019-07-10T19:27:59.000+02:00
complex: Fix hash function to work correctly
diff --git a/tests/snippets/builtin_complex.py b/tests/snippets/builtin_complex.py
@@ -94,6 +94,10 @@
 assert hash(complex(-float('inf'))) == hash(-float('inf'))
 assert hash(1j) != hash(1)
 
+# TODO: Find a way to test platform dependent values
+assert hash(3.1 - 4.2j) == hash(3.1 - 4.2j)
+assert hash(3.1 + 4.2j) == hash(3.1 + 4.2j)
+
 # numbers.Complex
 
 a = complex(3, 4)
diff --git a/vm/src/obj/objcomplex.rs b/vm/src/obj/objcomplex.rs
@@ -1,5 +1,6 @@
 use num_complex::Complex64;
 use num_traits::Zero;
+use std::num::Wrapping;
 
 use crate::function::OptionalArg;
 use crate::pyhash;
@@ -254,7 +255,7 @@ impl PyComplex {
     fn hash(&self, _vm: &VirtualMachine) -> pyhash::PyHash {
         let re_hash = pyhash::hash_float(self.value.re);
         let im_hash = pyhash::hash_float(self.value.im);
-
-        re_hash + im_hash * pyhash::IMAG
+        let ret = Wrapping(re_hash) + Wrapping(im_hash) * Wrapping(pyhash::IMAG);
+        ret.0
     }
 }
