[Bug fortran/33525] New: crash in if ( i .gt. 0 .and. a(i) .gt. 0 ) when a(0) is out of bounds

[Bug fortran/33525] New: crash in if ( i .gt. 0 .and. a(i) .gt. 0 ) when a(0) is out of bounds

[dusan dot turk at ijs dot si]

the if statement crashes the code:
> 
>       program t
>       integer*4 i
>       real*4 a(10)
>       do i = 1, 10
>          a(i) = i
>       end do
>       i = 0
>       if ( i .gt. 0 .and. a(i) .gt. 0 ) then
>          i = i + 1
>          write(*,*) i
>       end if
>       end
> 
>  $ gfortran -fbounds-check -o t.exe t.f
>  $ t.exe 
> Fortran runtime error: Array reference out of bounds for array 'a',
> lower bound of dimension 1 exceeded (in file 't.f', at line 8)
With all other FORTAN compilers I've worked so far this does not happen as
after the first condition is not fulfilled the second is never tested.
This problem makes impossible to develope a program in GFROTRAN environment.


-- 
           Summary: crash in if ( i .gt. 0 .and. a(i) .gt. 0 ) when a(0) is
                    out of bounds
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: blocker
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dusan dot turk at ijs dot si


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33525

[Bug fortran/33525] crash in if ( i .gt. 0 .and. a(i) .gt. 0 ) when a(0) is out of bounds

[kargl at gcc dot gnu dot org]

------- Comment #1 from kargl at gcc dot gnu dot org  2007-09-21 23:03 -------
The Fortran language does not guarantee the order of the
evaluation of the logical expression in your IF statement.
A fortran processor can try to evaluate "a(0) .gt. 0" before
the "i .gt. 0" expression.  Your code is broken and possibly
illegal Fortran.  Rewrite your code as you meant:

       i = 0
       if ( i .gt. 0) then
          if (a(i) .gt. 0 ) then
             i = i + 1
             write(*,*) i
          end if
       end if


-- 

kargl at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33525