>Number:         26933
>Category:       toolchain
>Synopsis:       lint incorrectly warns of right-shift of unsigned short
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Sep 13 01:06:00 UTC 2004
>Closed-Date:
>Last-Modified:
>Originator:     Jason R Thorpe
>Release:        NetBSD 2.0G
>Organization:
        -- Jason R. Thorpe <thorpej@shagadelic.org>
>Environment:
	
	
System: NetBSD yeah-baby.shagadelic.org 2.0G NetBSD 2.0G (YEAH-BABY-XP) #26: Thu Jul 15 08:26:49 PDT 2004 thorpej@yeah-baby.shagadelic.org:/u1/netbsd/src/sys/arch/i386/compile/YEAH-BABY-XP i386
Architecture: i386
Machine: i386
>Description:
	Lint incorrectly issues the following warning:

lintbug.c(5): warning: bitwise operation on signed value possibly nonportable [117]

	when it encounters a right-shift of an unsigned short in
	certain cases.

>How-To-Repeat:
	Run the following test case through:

	lint -chapbxzF -w -X 272 -i

void
bug(unsigned char *p, unsigned short u)
{

	*p = (u >> 8) & 0xffU;
}

	Changing the "unsigned short" in the test case to "unsigned int"
	causes the warning to go away.  Lint is possibly mis-promoting
	the argument?

	Worth noting that the following test case also fails:

void
bug(unsigned char *p, unsigned int x)
{
	unsigned short u = x & 0xffffU;

	*p = (u >> 8) & 0xffU;
}

	Ok, so maybe lint is just totally screwing up "unsigned short".

>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted: