pkg/43609: hugs98 overflow bug when printing Integers on platforms with sizeof(long) != sizeof(int)

[kretschm%cs.uni-bonn.de@localhost]

>Number:         43609
>Category:       pkg
>Synopsis:       hugs98 overflow bug when printing Integers on platforms with 
>sizeof(long) != sizeof(int)
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 13 06:25:00 +0000 2010
>Originator:     Matthias Kretschmer
>Release:        NetBSD 5.0.2_PATCH
>Organization:
>Environment:
NetBSD random87 5.0.2 NetBSD 5.0.2 (GENERIC) amd64
>Description:
If you convert Int to Integer using toInteger, then there is a sign extension 
bug in the underlying primitive.  This is only triggered on platforms with 
sizeof(long)==8 > sizeof(int)==4.

If you have the sign extension bug, then toInteger (minBound :: Int), toInteger 
(minBound :: Data.Int.Int32), etc. return false results.
>How-To-Repeat:
compile hugs98 on amd64 or any other LP64 platform and do the following in the 
interpreter:

Hugs> toInteger (minBound :: Int)
-18446744071562067968


where as it should read

Hugs> toInteger (minBound :: Int)
-2147483648
>Fix:
Changing src/bignums.c line 120 from

    no = (unsigned long)(-n);

to

    no = (unsigned long)(-(long)n);

solves the problem.