[FFmpeg-cvslog] r12620 - trunk/configure

[İsmail Dönmez]

On Sat, Mar 29, 2008 at 10:02 PM, matthieu castet
<castet.matthieu at free.fr> wrote:
>
> ?smail D?nmez wrote:
>  > On Fri, Mar 28, 2008 at 10:04 PM, matthieu castet
>  > <castet.matthieu at free.fr> wrote:
>  >> diego wrote:
>  >>  > Author: diego
>  >>  > Date: Fri Mar 28 12:53:37 2008
>  >>  > New Revision: 12620
>  >>  >
>  >>  > Log:
>  >>  > Replace hackish CFLAGS 64 bit test by a proper compilation check.
>  >>  > patch by ?smail D?nmez, ismail namtrac org
>  >>  >
>  >>  >
>  >>  > Modified:
>  >>  >    trunk/configure
>  >>  >
>  >>  > Modified: trunk/configure
>  >>  > ==============================================================================
>  >>
>  >>> +        check_cc <<EOF && enable fast_64bit && arch="x86_64"
>  >>  > +        int test[sizeof(char*) - 7];
>  >>  > +EOF
>  >>  Just for info gcc see "sizeof(char*) - 7" as a big integer not a
>  >>  negative integer.
>  >>
>  >>  The check still failed on 32 bits because of array overflow. I wonder if
>  >>  it was the expected behaviour.
>  >
>  > Yes thats the point, it won't compile on 32bit. Thats why we use check_cc.
>  my point was is there something in C standard that prevent to allocate
>  such big array ?
>
>  Yes gcc failed because of array overflow, but not all C compiler are gcc.
>
>  May be it could be more safe to make "sizeof(char*) - 7" signed and be
>  in the case of negative array (which is in the C standard).

sizeof(char*) is 4 on 32bit so you are trying to do int test[-3] which
should fail on all valid compilers.

Regards,
ismail

-- 
Never learn by your mistakes, if you do you may never dare to try again.