> > This seems pretty clear. C99 requires that storage be allocated
> >
> >for uninitialized objects, that an indeterminate value be stored
> >in the object when the declarator for the object is reached in the
> >block, that the last-stored value be retained for the duration of
> >the block.
> >
> >
> I think that is an incorrect interpretation. Remember the standard is
> always "as-if" when it gives an implementation approach. Please
> show a correct C program that can tell that gcc is not following
> the above scheme.
#include <stdio.h>
unsigned char
T (unsigned char x)
{
static int first = 1;
static unsigned char firstx;
if (first)
{
first = 0;
firstx = x;
return ~x;
}
if (x == firstx)
printf ("Behavior is pre GCC 4.0\n");
else
printf ("Behavior is GCC 4.0 and later\n");
return 0;
}
*** cut ***
extern int T (unsigned char);
int
foo (void)
{
int result;
unsigned char x;
result = T (x);
T (x);
return result;
}
int
main ()
{
return foo ();
}
Compile as follows:
gcc-3.4 -O2 -c T.c
gcc-3.4 -o und -O2 und.c T.o
./und
Behavior is pre GCC 4.0
gcc-4.0 -o und -O2 und.c T.o
Behavior is GCC 4.0 and later
That's what I see on hppa-unknown-linux-gnu. The 4.0 behavior is
caused by GCC using result for the second call to T, whereas 3.3
and 3.4 use the same undefined value for both calls to T.
Dave
--
J. David Anglin [EMAIL PROTECTED]
National Research Council of Canada (613) 990-0752 (FAX: 952-6602)
