265709 - suspicious cast in prnetdb on Solaris AMD64

Status: RESOLVED FIXED

(NSPR :: NSPR, defect, P3)

Description

[Julien Pierre]

When building NSPR on Solaris AMD64, I get the following warnings with gcc (but
not with Sun studio) :

../../../../pr/src/misc/prnetdb.c:2131: warning: cast from pointer to integer of
different size
../../../../pr/src/misc/prnetdb.c:2135: warning: cast to pointer from integer of
different size

The assignment on the first warning line is         :
PRIntn iter = (PRIntn) iterPtr;

Where iterPtr is an argument declared as void* .

The second warning line is :

        return (void *) iter;

PRIntn is typedef'ed to int in prtypes.h, which on this platform is smaller than
the size needed to hold a void* . It would therefore appear that this code is
broken for platforms where sizeof(void*) != sizeof(int), and needs to be changed
to use some other type than PRIntn. Wan-Teh, do you agree ?

Comment 1

[Wan-Teh Chang]

This code is broken only if the value of 'iter' cannot
be stored in a void* pointer without loss.  The maximum
value 'iter' can assume is the number of IP addresses of
the host, which is much smaller than 2^32 or 2^64.

Comment 2

[Wan-Teh Chang]

If you really want to eliminate the warnings, you
can try something like:

    PRIntn iter = (PRIntn)(PRPtrdiff) iterPtr;

    return (void *)(PRPtrdiff) iter;

Comment 3

[Julien Pierre]

Thanks for pointing out that the cast doesn't cause a real problem. Your
solution works and eliminates the gcc compiler warning on AMD64.

I would still like to see this fixed because the warning is not a benign one,
and is likely to waste time the next time we go over the compiler warnings.
Please check your solution to the tip. Thanks again !

Comment 4

[Wan-Teh Chang]

Do you want the warnings fixed on the NSPR_4_5_BRANCH, too?

Comment 5

[Julien Pierre]

Sure. Thanks !

Comment 6

[Julien Pierre]

Fixed on NSPR_4_5_BRANCH :

Checking in prnetdb.c;
/cvsroot/mozilla/nsprpub/pr/src/misc/prnetdb.c,v  <--  prnetdb.c
new revision: 3.41.2.1; previous revision: 3.41

Wan-Teh, please check in on the tip and close this bug.
Thanks.

I'm reducing this bug to P3 / trivial since this has only a compiler warning impact.

Comment 7

[Wan-Teh Chang]

Fix checked in on the NSPR trunk (NSPR 4.6) and
NSPRPUB_PRE_4_2_CLIENT_BRANCH (post Mozilla 1.8
Alpha 4).