Index: gcc/fortran/ChangeLog
===================================================================
--- gcc/fortran/ChangeLog	(Revision 226036)
+++ gcc/fortran/ChangeLog	(Arbeitskopie)
@@ -1,3 +1,15 @@
+2015-07-21  Andre Vehreschild  <vehre@gcc.gnu.org>
+
+	PR fortran/66035
+	* trans-expr.c (alloc_scalar_allocatable_for_subcomponent_assignment):
+	Compute the size to allocate for class and derived type objects
+	correclty.
+	(gfc_trans_subcomponent_assign): Only allocate memory for a
+	component when the object to assign is not an allocatable class
+	object (the memory is already present for allocatable class objects).
+	Furthermore use copy_class_to_class for assigning the rhs to the
+	component (may happen for dummy class objects on the rhs).
+
 2015-07-17  Alessandro Fanfarillo  <fanfarillo.gcc@gmail.com>
 
 	* trans-intrinsic.c (conv_co_collective): Remove redundant address
Index: gcc/fortran/trans-expr.c
===================================================================
--- gcc/fortran/trans-expr.c	(Revision 226036)
+++ gcc/fortran/trans-expr.c	(Arbeitskopie)
@@ -6732,6 +6732,29 @@
 				       TREE_TYPE (tmp), tmp,
 				       fold_convert (TREE_TYPE (tmp), size));
     }
+  else if (cm->ts.type == BT_CLASS)
+    {
+      gcc_assert (expr2->ts.type == BT_CLASS || expr2->ts.type == BT_DERIVED);
+      if (expr2->ts.type == BT_DERIVED)
+	{
+	  tmp = gfc_get_symbol_decl (expr2->ts.u.derived);
+	  size = TYPE_SIZE_UNIT (tmp);
+	}
+      else
+	{
+	  gfc_expr *e2vtab;
+	  gfc_se se;
+	  e2vtab = gfc_find_and_cut_at_last_class_ref (expr2);
+	  gfc_add_vptr_component (e2vtab);
+	  gfc_add_size_component (e2vtab);
+	  gfc_init_se (&se, NULL);
+	  gfc_conv_expr (&se, e2vtab);
+	  gfc_add_block_to_block (block, &se.pre);
+	  size = fold_convert (size_type_node, se.expr);
+	  gfc_free_expr (e2vtab);
+	}
+      size_in_bytes = size;
+    }
   else
     {
       /* Otherwise use the length in bytes of the rhs.  */
@@ -6859,7 +6882,8 @@
       gfc_add_expr_to_block (&block, tmp);
     }
   else if (init && (cm->attr.allocatable
-	   || (cm->ts.type == BT_CLASS && CLASS_DATA (cm)->attr.allocatable)))
+	   || (cm->ts.type == BT_CLASS && CLASS_DATA (cm)->attr.allocatable
+	       && expr->ts.type != BT_CLASS)))
     {
       /* Take care about non-array allocatable components here.  The alloc_*
 	 routine below is motivated by the alloc_scalar_allocatable_for_
Index: gcc/testsuite/ChangeLog
===================================================================
--- gcc/testsuite/ChangeLog	(Revision 226036)
+++ gcc/testsuite/ChangeLog	(Arbeitskopie)
@@ -1,3 +1,8 @@
+2015-07-21  Andre Vehreschild  <vehre@gcc.gnu.org>
+
+	PR fortran/66035
+	* gfortran.dg/structure_constructor_13.f03: New test.
+
 2015-07-21  Alex Velenko  <Alex.Velenko@arm.com>
 
 	Backport from mainline:
Index: gcc/testsuite/gfortran.dg/structure_constructor_13.f03
===================================================================
--- gcc/testsuite/gfortran.dg/structure_constructor_13.f03	(Revision 0)
+++ gcc/testsuite/gfortran.dg/structure_constructor_13.f03	(Arbeitskopie)
@@ -0,0 +1,28 @@
+! { dg-do run }
+!
+! Contributed by Melven Roehrig-Zoellner  <Melven.Roehrig-Zoellner@DLR.de>
+! PR fortran/66035
+
+program test_pr66035
+  type t
+  end type t
+  type w
+    class(t), allocatable :: c
+  end type w
+
+  type(t) :: o
+
+  call test(o)
+contains
+  subroutine test(o)
+    class(t), intent(inout) :: o
+    type(w), dimension(:), allocatable :: list
+
+    select type (o)
+      class is (t)
+        list = [w(o)] ! This caused an ICE
+      class default
+        call abort()
+    end select
+  end subroutine
+end program