From b43c51154222e376be658032e2de1f3bdc90d085 Mon Sep 17 00:00:00 2001
From: silmeth <sth.jaworski@gmail.com>
Date: Tue, 5 Feb 2019 19:49:14 +0100
Subject: [PATCH] fix range len() for negative and non-divisible steps

---
 vm/src/obj/objrange.rs | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/vm/src/obj/objrange.rs b/vm/src/obj/objrange.rs
index 5924cd048..7e25fd058 100644
--- a/vm/src/obj/objrange.rs
+++ b/vm/src/obj/objrange.rs
@@ -4,7 +4,7 @@ use super::super::pyobject::{
 use super::super::vm::VirtualMachine;
 use super::objint;
 use super::objtype;
-use num_bigint::{BigInt, ToBigInt};
+use num_bigint::{BigInt, ToBigInt, Sign};
 use num_traits::{One, Signed, ToPrimitive, Zero};
 
 #[derive(Debug, Clone)]
@@ -19,10 +19,13 @@ pub struct RangeType {
 impl RangeType {
     #[inline]
     pub fn len(&self) -> usize {
-        ((self.end.clone() - self.start.clone()) / self.step.clone())
-            .abs()
-            .to_usize()
-            .unwrap()
+        match self.step.sign() {
+            Sign::Plus if self.start < self.end =>
+                ((&self.end - &self.start - 1usize) / &self.step).to_usize().unwrap() + 1,
+            Sign::Minus if self.start > self.end =>
+                ((&self.start - &self.end - 1usize) / (-&self.step)).to_usize().unwrap() + 1,
+            _ => 0,
+        }
     }
 
     #[inline]