[Bug fortran/56293] Segfault when trying to access pass-by-reference value of a not-word-aligned REAL(16) / -fno-align-commons

[tobi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56293

--- Comment #7 from Tobias Schlüter <tobi at gcc dot gnu.org> 2013-03-11 00:15:43 UTC ---
(In reply to comment #6)
> > The question is also whether one can construct a fully standard-conform example
> > which fails without -fno-align-commons – and whether some real-world code uses
> > COMMON in a way that would fails with alignments/padding.
> 
>       program main
>       real a,f1,f2,d
>       common /foo/ a,f1,f2,d
>       a = 1.0
>       d = 1.0
>       call s1
>       end
>       subroutine s1
>       real a,b
>       double precision d
>       common /foo/ a,d,b
>       print *,a
>       print *,b
>       end

That's not valid.  I'm looking at the F95 working draft:
according to note 5.33
"""Association in different scoping units between objects of default type,
objects of double precision real type, and sequence structures is permitted
according to the rules for equivalence objects (5.5.1)."""

and in 5.5.1. we have
"""If an equivalence-object is of type default integer, default real, double
precision real, default complex, default logical, or numeric sequence type, all
of the objects in the equivalence set shall be of these types."""