Re: segfault in translate_common()

[Paul Thomas <paulthomas2 at wanadoo dot fr>]

Bernhard,

> If you comment out one of "toggle", the segfault goes away.
This example shows that your two toggles are not equivalent;

      module mod0
        double complex FOO
        common/bar/FOO
      contains
        subroutine eyeore ()   
          FOO = FOO + (1.0d0, 0.0d0)
        end subroutine eyeore
      end module mod0
      module mod1
!         use mod0 ! toggle
      end module mod1
      module mod2
        use mod0 ! toggle
        use mod1
      contains
        subroutine tigger ()   
          print *, FOO
        end subroutine tigger
      end module mod2

      use mod2
      FOO = (0.0d0, 1.0d0)
      call eyeore ()
      call tigger ()
      end

The assignment in the main program does not transmit to either 
subroutine.  With the toggle, as shown, eyeore succeeds in adding (1,0) 
to the FOO, seen by tigger.  With the other toggle, poor old tigger sees 
nothing at all.

Printing out the parse tree shows that common blocks like /bar/, 
/_0_bar/, /_1__0_bar/ and /_2__1__0_bar/ are in circulation.  
Read_module is obviously failing to check if there is already a common 
block of the same name that has been previously use associated.

The patch below fixes your problem but "perturbs" my fix for module 
equivalences; the test cases work perfectly but the module equivalences 
to common variables manage to be associated with different external 
symbols, which are none the less correctly aligned! I obviously need to 
understand this before emitting a patch and a test case.  Otherwise it 
regtests on FC3/Athlon.

If this turns out to be a valid fix, gfc_get_common can be simplified 
and the second argument removed, since it is now always zero.

Best regards

Paul T

Index: gcc/gcc/fortran/module.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/fortran/module.c,v
retrieving revision 1.34
diff -c -3 -p -r1.34 module.c
*** gcc/gcc/fortran/module.c    25 Jun 2005 00:40:35 -0000      1.34
--- gcc/gcc/fortran/module.c    11 Aug 2005 14:22:45 -0000
*************** Software Foundation, 51 Franklin Street,
*** 2908,2914 ****
       mio_lparen ();
       mio_internal_string (name);

!       p = gfc_get_common (name, 1);

       mio_symbol_ref (&p->head);
       mio_integer (&p->saved);
--- 2908,2914 ----
       mio_lparen ();
       mio_internal_string (name);

!       p = gfc_get_common (name, 0);

       mio_symbol_ref (&p->head);
       mio_integer (&p->saved);