[Bug fortran/46325] [4.6 Regression] gfortran.dg/char_initialiser_actual.f90 FAILs with -fstack-protector

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46325

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |burnus at gcc dot gnu.org

--- Comment #4 from Tobias Burnus <burnus at gcc dot gnu.org> 2010-11-11 21:58:42 UTC ---
(In reply to comment #2)
> If this is actually valid Fortran

Short answer: The reduced test program in comment 2 is invalid according to the
Fortran standard. Long answer below.


> program char_initialiser
>   character*5, dimension(3) :: x
>   character*5, dimension(:), pointer :: y
>   x=(/"is Ja","ne Fo","nda  "/)

So far so good. "y" is a pointer and "x" is a nonpointer, nontarget which thus
may not alias.


>   y => pfoo ((/"is Ja","ne Fo","nda  "/))

By itself, it looks valid.


>   function pfoo(ch2)
>      character*5, dimension(:), target  :: ch2
>      character*5, dimension(:), pointer :: pfoo
>      pfoo => ch2
>   end function pfoo

Also this function looks valid as "ch2" is a target (at least in the scope of
"pfoo"). However, as the actual argument associated with "pfoo" (namely "x") is
not a target, the pointer "pfoo" has the pointer associations status
"undefined" after "pfoo" -- that's still valid. Thus:

  y => pfoo ((/"is Ja","ne Fo","nda  "/))

is equivalent to

  y => <undefined pointer>

However, the following line is invalid:
    call afoo (y, x)
as the dummy arguments of "afoo" are not pointers and "y" has the status
undefined.


To put this in some legalize by quoting from Fortran 2008:

"12.5.2.4 Ordinary dummy variables" [...] "If the dummy argument has the TARGET
attribute and the effective argument does not have the TARGET attribute or is
an array section with a vector subscript, any pointers associated with the
dummy argument become undefined when execution of the procedure completes."

And: "7.1.9.2 Type, type parameters, and shape of a primary"
"If the pointer is not associated with a target, it may appear as a primary
only as an actual argument in a reference to a procedure whose corresponding
dummy argument is declared to be a pointer, or as the target in a pointer
assignment statement."