[Bug fortran/22304] gfortran silently changes values in equilvanence'd variables

["pault at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From pault at gcc dot gnu dot org  2005-08-05 06:08 -------
This is amusing.....

      integer o(4), b, c
      COMMON /IBM/ o
      EQUIVALENCE (o(1),b),(C,o(4))
      o(3)=1
      CALL MYSUB1
      CALL MYSUB2
      END 
 
      subroutine MYSUB1 
      integer o (4), b, c
      COMMON /IBM/ o 
      EQUIVALENCE (o(1), b), (o(4), c) 
      WRITE (6,*) "IN MYSUB1: o(3)= ", o(3) 
      RETURN 
      END

      subroutine MYSUB2
      integer o (4), b, c
      COMMON /IBM/ o 
      EQUIVALENCE (o(1), b), (c, o(4)) 
      WRITE (6,*) "IN MYSUB2: o(3)= ", o(3) 
      RETURN 
      END 
 
 IN MYSUB1: o(3)=            0
 IN MYSUB2: o(3)=    134519416

The code shows that SUB1 references the common block, whereas SUB2 goes for a
home grown equivalence.  This is a good clue as to where things are failing.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22304