https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103662
--- Comment #15 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Putting a breakpoint on new_alias_set, I see that
RECORD_TYPE sq gets alias set 1
RECORD_TYPE s gets alias set 9
RECORD_TYPE t gets alias set 10
Those are
type sq
sequence
integer :: i
end type sq
and
type, bind(c) :: s
integer (c_int) :: k
end type s
type t
sequence
integer :: k
end type t
in the testcase. The testcase stores through the sq type and reads through
pointer to s and pointer to t type. As the alias sets are different, for the
middle-end the testcase is invalid.
Now, the question is what is the Fortran unlimited polymorphic semantics, if
one can store through one type and read through a different type which just has
the same layout, or if it also has to use the same name etc., or if it is even
acceptable to store through say a type with a pair of integers and read through
a type with double precision etc.
GCC has types that can alias anything, so if the semantics is like that,
unlimited polymorphic middle-end pointers perhaps should use that.
Or the testcase is invalid and has to use type sq in foo as well. Or we need
to ensure sq and s/t above have the same alias set.
