[Bug fortran/106731] ICE on automatic array of derived type with DTIO

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106731

kargl at gcc dot gnu.org changed:

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

--- Comment #3 from kargl at gcc dot gnu.org ---
(In reply to federico from comment #0)
> A derived type that has user-defined I/O causes ICE on all gfortran versions
> 7 to 12.1.0, whenever it's being used as an automatic object.
> 
> The error is at 
> 
> 
>    63 |         type(t) :: automatic(n)
>       |                               1
> internal compiler error: in gfc_trans_auto_array_allocation, at
> fortran/trans-array.cc:6617
> 
> This does not happen if the derived type is allocated.
> 
> Here's the simplest example: 
> 
> module causes_ice
>     implicit none
> 
>     type :: t
>         real(8) :: x
>         contains
>         procedure, private :: write_formatted
>         generic :: write(formatted) => write_formatted
>     end type t
> 
>     contains
> 
>     subroutine write_formatted(this, unit, iotype, v_list, iostat, iomsg)
>        class(t), intent(in) :: this
>        integer, intent(in) :: unit
>        character(*), intent(in) :: iotype
>        integer, intent(in) :: v_list(:)
>        integer, intent(out) :: iostat
>        character(*), intent(inout) :: iomsg
>        write(unit, '(a)', iostat=iostat, iomsg=iomsg) 'dummy'
>     end subroutine write_formatted
> 
> end module causes_ice
> 
> module use_t
>     use causes_ice
>     implicit none
> 
>     public :: automatic_alloc
> 
>     contains
> 
>     subroutine automatic_alloc(n)
>         integer, intent(in) :: n
> 
>         ! Automatic array: ICE!
>         type(t) :: automatic(n)
> 
>         ! Allocatable: works
>         type(t), allocatable :: alloc(:)
>         allocate(alloc(n))
> 
>         ! Do anything
>         print *, 'n=',n,automatic(n)%x
> 
>     end subroutine automatic_alloc
> 
> end module use_t
> 
> program test
>     use use_t
>     call automatic_alloc(1)
> end program test
> 
> I could find other DTIO-related bugs, but none seemed related with the
> allocation type.

You're hitting an assert() in trans-array.cc.  It's unclear to me why the
assert() is there.  If it is commented out, the code compiles and executes.

% git diff gcc/fortran/trans-array.cc | cat
diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index 05134952db4..c5916aeee53 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -6614,7 +6614,7 @@ gfc_trans_auto_array_allocation (tree decl, gfc_symbol *
sym,
   type = TREE_TYPE (type);

   gcc_assert (!sym->attr.use_assoc);
-  gcc_assert (!TREE_STATIC (decl));
+//  gcc_assert (!TREE_STATIC (decl));
   gcc_assert (!sym->module);

   if (sym->ts.type == BT_CHARACTER