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From Mark Hindess <mark.hind...@googlemail.com>
Subject Re: [classlib][build] failure?
Date Wed, 20 Sep 2006 09:14:59 GMT

On 20 September 2006 at 10:06, Mark Hindess <mark.hindess@googlemail.com> wrote:
> 
> On 20 September 2006 at 10:03, "Leo Li" <liyilei1979@gmail.com> wrote:
> >
> > Hi, all:
> > 
> > Since I am not an expert of gcc, I think we need a guru to set the flags in
> > makefile of linux:
> > 1. It will report any required warnings and regard it as error to lead a
> > failure build so that it is forced for us to correct it.
> > 
> > 2. It can avoid to stop building due to such warnings:
> > 
> > In OSFileSystem.c, we have:
> > JNIEXPORT jlong JNICALL
> > Java_org_apache_harmony_luni_platform_OSFileSystem_readDirectImpl
> >   (JNIEnv * env, jobject thiz, jlong fd, jlong buf, jint offset, jint
> > nbytes)
> > {
> >   PORT_ACCESS_FROM_ENV (env);
> >   return (jlong) hyfile_read ((IDATA) fd, (void *) (buf+offset), (IDATA)
> > nbytes);
> > }
> > Actually, the hyfile_read returns a int32 while the jlong is int64. I think
> > the warning seems to be not avoidable.
> 
> I don't think that is the problem.  Casting from 32bit to 64bit is going
> to lead to a loss of information.

Oops.  I meant "isn't going to".
-Mark.

> > I have had tried some flags, but I have not got what I want.
> > Any good suggestion?
> 
> The problem occurs because (buf+offset) is a 64bit value (since buf is
> 64bit) and void* is a 32bit value (on x86).  If we cast (buf+offset) to
> a 32bit value before casting to (void*) the warning will be removed.
> 
> IDATA (and UDATA) are defined to be integers of the same size as 
> pointers for a given platform so if them for the cast then the warning
> can be avoided (and the code will still be correct on x86_64).
> 
> So something like:
> 
>   return (jlong) hyfile_read ((IDATA) fd,
>                               (void *) ((IDATA)(buf+offset)),
>                               (IDATA) nbytes);
> 
> (I've not tested this and each case should be looked at to see if the
> cast is really valid.)
> 
> Regards,
>  Mark.
> 
> 
> 
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