[Bug libfortran/24685] real(16) formatted input is broken for huge values (gfortran.dg/default_format_2.f90)

[fxcoudert at gcc dot gnu dot org]

------- Comment #30 from fxcoudert at gcc dot gnu dot org  2008-02-23 20:10 -------
On powerpc-apple-darwin9.2, gfortran.dg/large_real_kind_form_io_2.f90 fails for
that reason:

$ cat a.f90
  real(kind=16) :: a,b
  character(len=180) :: tmp

  b = 8.98846567431157953864652595394501287669662887245e307_16
  write (tmp, *) b
  read (tmp, *) a
  write(*,"(G70.55E4)") b
  write(*,"(G70.55E4)") a
  write(*,"(G70.55E4)") a-b
  if (a /= b) print *, "#####"

end
$ ./bin/gfortran a.f90 && ./a.out
       0.8988465674311579538646525953945123668100000000000000000E+0308
       0.8988465674311579538646525953945123668100000000000000000E+0308
       0.1107913932560222642718302084617242634400000000000000000E+0277
 #####

But, as the following C testcase shows, that's not a gfortran problem, but
rather a libc issue on darwin:

$ cat a.c
#include <stdio.h>
#include <string.h>
int main(void) {
  long double x, y = 8.98846567431157953864652595394501287669662887245e307L;
  char buf[79];
  memset (buf, ' ', sizeof(buf));
  sprintf (buf, "%60.70Lg", y);
  puts (buf);
  sscanf (buf, "%Lg", &x);
  memset (buf, ' ', sizeof(buf));
  sprintf (buf, "%60.70Lg", x);
  puts (buf);
  printf ("%60.70Lg\n", x-y);
  return 0;
}
$ gcc a.c && ./a.out
8.988465674311579538646525953945123668089884894711532863671504057886634e+307
8.988465674311579538646525953945123668089884894711532863671504057886634e+307
1.107913932560222642718302084617242634394213707491304322373697056856707e+276

I have reported that issue to Apple as radar #5761818, we'll see if it is
fixed, but I doubt it (no new PowerPC sold by Apple, and generally little
interest in long double). I have thus XFAILed
gfortran.dg/large_real_kind_form_io_2.f90 on powerpc*-apple-darwin*.

As comment #27 says, this doesn't fail on sparc-solaris, I'm closing this as
INVALID. Please reopen if you have a testcase on another target where the issue
is not due to a faulty libc.


-- 

fxcoudert at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24685