[Bug fortran/70842] [4.9/5/6/7 Regression] internal compiler error with character members within a polymorphic pointer

[kargl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70842

--- Comment #5 from kargl at gcc dot gnu.org ---
(In reply to Gerhard Steinmetz from comment #4)
> ICE for both release and experimental :
> 
> 
> $ gfortran-6 pr70842.f90
> f951: internal compiler error: in gfc_add_component_ref, at
> fortran/class.c:241
> 

With the patch I posted earlier today and code in comment #1, I see

 gfc7 -c a.f90
a.f90:14:30:

         print*, len(me%string)
                              1
Error: Data transfer element at (1) cannot be polymorphic unless it
is processed by a defined input/output procedure

I don't use CLASS and know little about its expected behavior.
Is the above even remotely right?