Bug 16526 - Mono's BigInteger converts a large negative to a positive int64
Summary: Mono's BigInteger converts a large negative to a positive int64
Status: RESOLVED FIXED
Alias: None
Product: Class Libraries
Classification: Mono
Component: General ()
Version: master
Hardware: PC Windows
: --- normal
Target Milestone: Untriaged
Assignee: Rodrigo Kumpera
URL:
Depends on:
Blocks:
 
Reported: 2013-11-30 10:43 UTC by donsyme
Modified: 2013-12-06 11:14 UTC (History)
2 users (show)

Tags:
Is this bug a regression?: ---
Last known good build:

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Status:
RESOLVED FIXED

Description donsyme 2013-11-30 10:43:26 UTC
This is a corner case bug in the Mono BigInteger implementation. 

Mono should raise a System.OverflowException for this obscure case when converting a large negative biginteger to an int64. Instead it returns a positive int64.

open System.Numerics

let x = -1I * BigInteger.Pow(2I,63) 
 int64 (x - 1I)

// The value is -9223372036854775809
// Mono gives: 9223372036854775807L  (very incorrect)
// .NET gives: System.OverflowException
Comment 1 Rodrigo Kumpera 2013-12-06 11:14:25 UTC
Fixed in master.