Hi all,

commited as r221591 to gcc_4.9-branch. Okayed by Paul via IRC on 2015-03-22.
Thanks, Paul.

gcc/fortran/ChangeLog

2015-03-23  Andre Vehreschild  <ve...@gmx.de>
            Janus Weil  <ja...@gcc.gnu.org>

        Backported from mainline
        PR fortran/60255
        Initial patch version: Janus Weil
        * class.c (gfc_get_len_component): New.
        (gfc_build_class_symbol): Add _len component to unlimited
        polymorphic entities.
        (find_intrinsic_vtab): Removed emitting of error message.
        * gfortran.h: Added prototype for gfc_get_len_component.
        * simplify.c (gfc_simplify_len): Use _len component where
        available.
        * trans-expr.c (gfc_class_len_get): New.
        (gfc_conv_intrinsic_to_class): Add handling for deferred
        character arrays.
        (gfc_conv_structure): Treat _len component correctly.
        (gfc_conv_expr): Prevent bind_c handling when not required.
        (gfc_trans_pointer_assignment): Propagate _len component.
        * trans-stmt.c (class_has_len_component): New.
        (trans_associate_var): _len component treatement for associate
        context.
        (gfc_trans_allocate): Same as for trans_associate_var()
        * trans.h: Add prototype for gfc_class_len_get.

gcc/testsuite/ChangeLog

2015-03-20  Andre Vehreschild  <ve...@gmx.de>

        Backport from mainline
        PR fortran/60255
        * gfortran.dg/unlimited_polymorphic_2.f03: Removed error.
        Converted from dos to unix line endings.
        * gfortran.dg/unlimited_polymorphic_20.f03: New test.

Regards,
        Andre
-- 
Andre Vehreschild * Email: vehre ad gmx dot de 
Index: gcc/testsuite/ChangeLog
===================================================================
--- gcc/testsuite/ChangeLog	(Revision 221590)
+++ gcc/testsuite/ChangeLog	(Arbeitskopie)
@@ -1,3 +1,11 @@
+2015-03-20  Andre Vehreschild  <ve...@gmx.de>
+
+	Backport from mainline
+	PR fortran/60255
+	* gfortran.dg/unlimited_polymorphic_2.f03: Removed error.
+	Converted from dos to unix line endings.
+	* gfortran.dg/unlimited_polymorphic_20.f03: New test.
+
 2015-03-23  Yvan Roux  <yvan.r...@linaro.org>
 
 	Backport from trunk r216841.
Index: gcc/testsuite/gfortran.dg/unlimited_polymorphic_2.f03
===================================================================
--- gcc/testsuite/gfortran.dg/unlimited_polymorphic_2.f03	(Revision 221590)
+++ gcc/testsuite/gfortran.dg/unlimited_polymorphic_2.f03	(Arbeitskopie)
@@ -1,80 +1,80 @@
-! { dg-do compile }
-!
-! Test the most important constraints unlimited polymorphic entities
-!
-! Contributed by Paul Thomas  <pa...@gcc.gnu.org>
-!            and Tobias Burnus <bur...@gcc.gnu.org>
-!
-  CHARACTER(:), allocatable, target :: chr ! { dg-error "TODO: Deferred character length variable" }
-! F2008: C5100
-  integer :: i(2)
-  logical :: flag
-  class(*), pointer :: u1, u2(:) ! { dg-error "cannot appear in COMMON" }
-  common u1
-  u1 => chr
-! F2003: C625
-  allocate (u1) ! { dg-error "requires either a type-spec or SOURCE tag" }
-  allocate (real :: u1)
-  Allocate (u1, source = 1.0)
-
-! F2008: C4106
-  u2 = [u1] ! { dg-error "shall not be unlimited polymorphic" }
-
-  i = u2 ! { dg-error "Can\\'t convert CLASS\\(\\*\\)" }
-
-! Repeats same_type_as_1.f03 for unlimited polymorphic u2
-  flag = same_type_as (i, u2) ! { dg-error "cannot be of type INTEGER" }
-  flag = extends_type_of (i, u2) ! { dg-error "cannot be of type INTEGER" }
-
-contains
-
-! C717 (R735) If data-target is unlimited polymorphic,
-! data-pointer-object shall be unlimited polymorphic, of a sequence
-! derived type, or of a type with the BIND attribute.
-!
-  subroutine bar
-
-    type sq
-      sequence
-      integer :: i
-    end type sq
-
-    type(sq), target :: x
-    class(*), pointer :: y
-    integer, pointer :: tgt
-
-    x%i = 42
-    y => x
-    call foo (y)
-
-    y => tgt ! This is OK, of course.
-    tgt => y ! { dg-error "must be unlimited polymorphic" }
-
-    select type (y) ! This is the correct way to accomplish the previous
-      type is (integer)
-        tgt => y
-    end select
-
-  end subroutine bar
-
-
-  subroutine foo(tgt)
-    class(*), pointer, intent(in) :: tgt
-    type t
-      sequence
-      integer :: k
-    end type t
-
-    type(t), pointer :: ptr
-
-    ptr => tgt ! C717 allows this.
-
-    select type (tgt)
-! F03:C815 or F08:C839
-      type is (t) ! { dg-error "shall not specify a sequence derived type" }
-        ptr => tgt ! { dg-error "Expected TYPE IS" }
-    end select
-
-    print *, ptr%k
-  end subroutine foo
-END
+! { dg-do compile }
+!
+! Test the most important constraints unlimited polymorphic entities
+!
+! Contributed by Paul Thomas  <pa...@gcc.gnu.org>
+!            and Tobias Burnus <bur...@gcc.gnu.org>
+!
+  CHARACTER(:), allocatable, target :: chr
+! F2008: C5100
+  integer :: i(2)
+  logical :: flag
+  class(*), pointer :: u1, u2(:) ! { dg-error "cannot appear in COMMON" }
+  common u1
+  u1 => chr
+! F2003: C625
+  allocate (u1) ! { dg-error "requires either a type-spec or SOURCE tag" }
+  allocate (real :: u1)
+  Allocate (u1, source = 1.0)
+
+! F2008: C4106
+  u2 = [u1] ! { dg-error "shall not be unlimited polymorphic" }
+
+  i = u2 ! { dg-error "Can\\'t convert CLASS\\(\\*\\)" }
+
+! Repeats same_type_as_1.f03 for unlimited polymorphic u2
+  flag = same_type_as (i, u2) ! { dg-error "cannot be of type INTEGER" }
+  flag = extends_type_of (i, u2) ! { dg-error "cannot be of type INTEGER" }
+
+contains
+
+! C717 (R735) If data-target is unlimited polymorphic,
+! data-pointer-object shall be unlimited polymorphic, of a sequence
+! derived type, or of a type with the BIND attribute.
+!
+  subroutine bar
+
+    type sq
+      sequence
+      integer :: i
+    end type sq
+
+    type(sq), target :: x
+    class(*), pointer :: y
+    integer, pointer :: tgt
+
+    x%i = 42
+    y => x
+    call foo (y)
+
+    y => tgt ! This is OK, of course.
+    tgt => y ! { dg-error "must be unlimited polymorphic" }
+
+    select type (y) ! This is the correct way to accomplish the previous
+      type is (integer)
+        tgt => y
+    end select
+
+  end subroutine bar
+
+
+  subroutine foo(tgt)
+    class(*), pointer, intent(in) :: tgt
+    type t
+      sequence
+      integer :: k
+    end type t
+
+    type(t), pointer :: ptr
+
+    ptr => tgt ! C717 allows this.
+
+    select type (tgt)
+! F03:C815 or F08:C839
+      type is (t) ! { dg-error "shall not specify a sequence derived type" }
+        ptr => tgt ! { dg-error "Expected TYPE IS" }
+    end select
+
+    print *, ptr%k
+  end subroutine foo
+END
Index: gcc/testsuite/gfortran.dg/unlimited_polymorphic_20.f03
===================================================================
--- gcc/testsuite/gfortran.dg/unlimited_polymorphic_20.f03	(Revision 0)
+++ gcc/testsuite/gfortran.dg/unlimited_polymorphic_20.f03	(Revision 221591)
@@ -0,0 +1,104 @@
+! { dg-do run }
+!
+! Testing fix for PR fortran/60255
+!
+! Author: Andre Vehreschild <ve...@gmx.de>
+!
+MODULE m
+
+contains
+  subroutine bar (arg, res)
+    class(*) :: arg
+    character(100) :: res
+    select type (w => arg)
+      type is (character(*))
+        write (res, '(I2)') len(w)
+    end select
+  end subroutine
+
+END MODULE
+
+program test
+    use m;
+    implicit none
+    character(LEN=:), allocatable, target :: S
+    character(LEN=100) :: res
+    class(*), pointer :: ucp
+    call sub1 ("long test string", 16)
+    call sub2 ()
+    S = "test"
+    ucp => S
+    call sub3 (ucp)
+    call sub4 (S, 4)
+    call sub4 ("This is a longer string.", 24)
+    call bar (S, res)
+    if (trim (res) .NE. " 4") call abort ()
+    call bar(ucp, res)
+    if (trim (res) .NE. " 4") call abort ()
+
+contains
+
+    subroutine sub1(dcl, ilen)
+        character(len=*), target :: dcl
+        integer(4) :: ilen
+        character(len=:), allocatable :: hlp
+        class(*), pointer :: ucp
+
+        ucp => dcl
+
+        select type (ucp)
+        type is (character(len=*))
+            if (len(dcl) .NE. ilen) call abort ()
+            if (len(ucp) .NE. ilen) call abort ()
+            hlp = ucp
+            if (len(hlp) .NE. ilen) call abort ()
+        class default
+            call abort()
+        end select
+    end subroutine
+
+    subroutine sub2
+        character(len=:), allocatable, target :: dcl
+        class(*), pointer :: ucp
+
+        dcl = "ttt"
+        ucp => dcl
+
+        select type (ucp)
+        type is (character(len=*))
+            if (len(ucp) .ne. 3) call abort ()
+        class default
+            call abort()
+        end select
+    end subroutine
+
+    subroutine sub3(ucp)
+        character(len=:), allocatable :: hlp
+        class(*), pointer :: ucp
+
+        select type (ucp)
+        type is (character(len=*))
+            if (len(ucp) .ne. 4) call abort ()
+            hlp = ucp
+            if (len(hlp) .ne. 4) call abort ()
+        class default
+            call abort()
+        end select
+    end subroutine
+
+    subroutine sub4(ucp, ilen)
+        character(len=:), allocatable :: hlp
+        integer(4) :: ilen
+        class(*) :: ucp
+
+        select type (ucp)
+        type is (character(len=*))
+            if (len(ucp) .ne. ilen) call abort ()
+            hlp = ucp
+            if (len(hlp) .ne. ilen) call abort ()
+        class default
+            call abort()
+        end select
+    end subroutine
+end program
+
Index: gcc/fortran/simplify.c
===================================================================
--- gcc/fortran/simplify.c	(Revision 221590)
+++ gcc/fortran/simplify.c	(Arbeitskopie)
@@ -3690,6 +3690,14 @@
       mpz_set (result->value.integer, e->ts.u.cl->length->value.integer);
       return range_check (result, "LEN");
     }
+  else if (e->expr_type == EXPR_VARIABLE && e->ts.type == BT_CHARACTER
+	   && e->symtree->n.sym
+	   && e->symtree->n.sym->assoc && e->symtree->n.sym->assoc->target
+	   && e->symtree->n.sym->assoc->target->ts.type == BT_DERIVED)
+    /* The expression in assoc->target points to a ref to the _data component
+       of the unlimited polymorphic entity.  To get the _len component the last
+       _data ref needs to be stripped and a ref to the _len component added.  */
+    return gfc_get_len_component (e->symtree->n.sym->assoc->target);
   else
     return NULL;
 }
Index: gcc/fortran/trans-expr.c
===================================================================
--- gcc/fortran/trans-expr.c	(Revision 221590)
+++ gcc/fortran/trans-expr.c	(Arbeitskopie)
@@ -92,6 +92,7 @@
    in future implementations.  Use the corresponding APIs.  */
 #define CLASS_DATA_FIELD 0
 #define CLASS_VPTR_FIELD 1
+#define CLASS_LEN_FIELD 2
 #define VTABLE_HASH_FIELD 0
 #define VTABLE_SIZE_FIELD 1
 #define VTABLE_EXTENDS_FIELD 2
@@ -146,6 +147,20 @@
 }
 
 
+tree
+gfc_class_len_get (tree decl)
+{
+  tree len;
+  if (POINTER_TYPE_P (TREE_TYPE (decl)))
+    decl = build_fold_indirect_ref_loc (input_location, decl);
+  len = gfc_advance_chain (TYPE_FIELDS (TREE_TYPE (decl)),
+			    CLASS_LEN_FIELD);
+  return fold_build3_loc (input_location, COMPONENT_REF,
+			  TREE_TYPE (len), decl, len,
+			  NULL_TREE);
+}
+
+
 static tree
 gfc_vtable_field_get (tree decl, int field)
 {
@@ -599,6 +614,45 @@
 	}
     }
 
+  /* When the actual arg is a char array, then set the _len component of the
+     unlimited polymorphic entity, too.  */
+  if (e->ts.type == BT_CHARACTER)
+    {
+      ctree = gfc_class_len_get (var);
+      /* Start with parmse->string_length because this seems to be set to a
+	 correct value more often.  */
+      if (parmse->string_length)
+	  gfc_add_modify (&parmse->pre, ctree, parmse->string_length);
+      /* When the string_length is not yet set, then try the backend_decl of
+	 the cl.  */
+      else if (e->ts.u.cl->backend_decl)
+          gfc_add_modify (&parmse->pre, ctree, e->ts.u.cl->backend_decl);
+      /* If both of the above approaches fail, then try to generate an
+	 expression from the input, which is only feasible currently, when the
+	 expression can be evaluated to a constant one.  */
+      else
+	{
+	  /* Try to simplify the expression.  */
+	  gfc_simplify_expr (e, 0);
+	  if (e->expr_type == EXPR_CONSTANT && !e->ts.u.cl->resolved)
+	    {
+	      /* Amazingly all data is present to compute the length of a
+		 constant string, but the expression is not yet there.  */
+	      e->ts.u.cl->length = gfc_get_constant_expr (BT_INTEGER, 4,
+							  &e->where);
+	      mpz_set_ui (e->ts.u.cl->length->value.integer,
+			  e->value.character.length);
+	      gfc_conv_const_charlen (e->ts.u.cl);
+	      e->ts.u.cl->resolved = 1;
+	      gfc_add_modify (&parmse->pre, ctree, e->ts.u.cl->backend_decl);
+	    }
+	  else
+	    {
+	      gfc_error ("Can't compute the length of the char array at %L.",
+			 &e->where);
+	    }
+	}
+    }
   /* Pass the address of the class object.  */
   parmse->expr = gfc_build_addr_expr (NULL_TREE, var);
 }
@@ -6193,7 +6247,7 @@
 	 of EXPR_NULL,... by default, the static nullify is not needed
 	 since this is done every time we come into scope.  */
       if (!c->expr || (cm->attr.allocatable && cm->attr.flavor != FL_PROCEDURE))
-        continue;
+	continue;
 
       if (cm->initializer && cm->initializer->expr_type != EXPR_NULL
 	  && strcmp (cm->name, "_extends") == 0
@@ -6211,6 +6265,10 @@
 	  val = TYPE_SIZE_UNIT (gfc_get_derived_type (cm->ts.u.derived));
 	  CONSTRUCTOR_APPEND_ELT (v, cm->backend_decl, val);
 	}
+      else if (cm->ts.type == BT_INTEGER && strcmp (cm->name, "_len") == 0)
+	CONSTRUCTOR_APPEND_ELT (v, cm->backend_decl,
+				fold_convert (TREE_TYPE (cm->backend_decl),
+					      integer_zero_node));
       else
 	{
 	  val = gfc_conv_initializer (c->expr, &cm->ts,
@@ -6287,7 +6345,8 @@
      null_pointer_node.  C_PTR and C_FUNPTR are converted to match the
      typespec for the C_PTR and C_FUNPTR symbols, which has already been
      updated to be an integer with a kind equal to the size of a (void *).  */
-  if (expr->ts.type == BT_DERIVED && expr->ts.u.derived->ts.f90_type == BT_VOID)
+  if (expr->ts.type == BT_DERIVED && expr->ts.u.derived->ts.f90_type == BT_VOID
+      && expr->ts.u.derived->attr.is_bind_c)
     {
       if (expr->expr_type == EXPR_VARIABLE
 	  && (expr->symtree->n.sym->intmod_sym_id == ISOCBINDING_NULL_PTR
@@ -6552,6 +6611,27 @@
 	rse.expr = build_fold_indirect_ref_loc (input_location,
 					    rse.expr);
 
+      /* For string assignments to unlimited polymorphic pointers add an
+	 assignment of the string_length to the _len component of the
+	 pointer.  */
+      if ((expr1->ts.type == BT_CLASS || expr1->ts.type == BT_DERIVED)
+	  && expr1->ts.u.derived->attr.unlimited_polymorphic
+	  && (expr2->ts.type == BT_CHARACTER ||
+	      ((expr2->ts.type == BT_DERIVED || expr2->ts.type == BT_CLASS)
+	       && expr2->ts.u.derived->attr.unlimited_polymorphic)))
+	{
+	  gfc_expr *len_comp;
+	  gfc_se se;
+	  len_comp = gfc_get_len_component (expr1);
+	  gfc_init_se (&se, NULL);
+	  gfc_conv_expr (&se, len_comp);
+
+	  /* ptr % _len = len (str)  */
+	  gfc_add_modify (&block, se.expr, rse.string_length);
+	  lse.string_length = se.expr;
+	  gfc_free_expr (len_comp);
+	}
+
       gfc_add_block_to_block (&block, &lse.pre);
       gfc_add_block_to_block (&block, &rse.pre);
 
Index: gcc/fortran/class.c
===================================================================
--- gcc/fortran/class.c	(Revision 221590)
+++ gcc/fortran/class.c	(Arbeitskopie)
@@ -34,6 +34,12 @@
              (pointer/allocatable/dimension/...).
     * _vptr: A pointer to the vtable entry (see below) of the dynamic type.
 
+    Only for unlimited polymorphic classes:
+    * _len:  An integer(4) to store the string length when the unlimited
+             polymorphic pointer is used to point to a char array.  The '_len'
+             component will be zero when no character array is stored in
+             '_data'.
+
    For each derived type we set up a "vtable" entry, i.e. a structure with the
    following fields:
     * _hash:     A hash value serving as a unique identifier for this type.
@@ -544,10 +550,48 @@
 }
 
 
+/* Get the _len component from a class/derived object storing a string.
+   For unlimited polymorphic entities a ref to the _data component is available
+   while a ref to the _len component is needed.  This routine traverses the
+   ref-chain and strips the last ref to a _data from it replacing it with a
+   ref to the _len component.  */
+
+gfc_expr *
+gfc_get_len_component (gfc_expr *e)
+{
+  gfc_expr *ptr;
+  gfc_ref *ref, **last;
+
+  ptr = gfc_copy_expr (e);
+
+  /* We need to remove the last _data component ref from ptr.  */
+  last = &(ptr->ref);
+  ref = ptr->ref;
+  while (ref)
+    {
+      if (!ref->next
+	  && ref->type == REF_COMPONENT
+	  && strcmp ("_data", ref->u.c.component->name)== 0)
+	{
+	  gfc_free_ref_list (ref);
+	  *last = NULL;
+	  break;
+	}
+      last = &(ref->next);
+      ref = ref->next;
+    }
+  /* And replace if with a ref to the _len component.  */
+  gfc_add_component_ref (ptr, "_len");
+  return ptr;
+}
+
+
 /* Build a polymorphic CLASS entity, using the symbol that comes from
    build_sym. A CLASS entity is represented by an encapsulating type,
    which contains the declared type as '_data' component, plus a pointer
-   component '_vptr' which determines the dynamic type.  */
+   component '_vptr' which determines the dynamic type.  When this CLASS
+   entity is unlimited polymorphic, then also add a component '_len' to
+   store the length of string when that is stored in it.  */
 
 bool
 gfc_build_class_symbol (gfc_typespec *ts, symbol_attribute *attr,
@@ -645,6 +689,8 @@
       if (!gfc_add_component (fclass, "_vptr", &c))
 	return false;
       c->ts.type = BT_DERIVED;
+      c->attr.access = ACCESS_PRIVATE;
+      c->attr.pointer = 1;
 
       if (ts->u.derived->attr.unlimited_polymorphic)
 	{
@@ -651,13 +697,20 @@
 	  vtab = gfc_find_derived_vtab (ts->u.derived);
 	  gcc_assert (vtab);
 	  c->ts.u.derived = vtab->ts.u.derived;
+
+	  /* Add component '_len'.  Only unlimited polymorphic pointers may
+             have a string assigned to them, i.e., only those need the _len
+             component.  */
+	  if (!gfc_add_component (fclass, "_len", &c))
+	    return false;
+	  c->ts.type = BT_INTEGER;
+	  c->ts.kind = 4;
+	  c->attr.access = ACCESS_PRIVATE;
+	  c->attr.artificial = 1;
 	}
       else
 	/* Build vtab later.  */
 	c->ts.u.derived = NULL;
-
-      c->attr.access = ACCESS_PRIVATE;
-      c->attr.pointer = 1;
     }
 
   if (!ts->u.derived->attr.unlimited_polymorphic)
@@ -2434,18 +2487,9 @@
   gfc_symbol *copy = NULL, *src = NULL, *dst = NULL;
   int charlen = 0;
 
-  if (ts->type == BT_CHARACTER)
-    {
-      if (ts->deferred)
-	{
-	  gfc_error ("TODO: Deferred character length variable at %C cannot "
-		     "yet be associated with unlimited polymorphic entities");
-	  return NULL;
-	}
-      else if (ts->u.cl && ts->u.cl->length
-	       && ts->u.cl->length->expr_type == EXPR_CONSTANT)
-	charlen = mpz_get_si (ts->u.cl->length->value.integer);
-    }
+  if (ts->type == BT_CHARACTER && !ts->deferred && ts->u.cl && ts->u.cl->length
+      && ts->u.cl->length->expr_type == EXPR_CONSTANT)
+    charlen = mpz_get_si (ts->u.cl->length->value.integer);
 
   /* Find the top-level namespace.  */
   for (ns = gfc_current_ns; ns; ns = ns->parent)
Index: gcc/fortran/gfortran.h
===================================================================
--- gcc/fortran/gfortran.h	(Revision 221590)
+++ gcc/fortran/gfortran.h	(Arbeitskopie)
@@ -3173,6 +3173,7 @@
 bool gfc_is_class_container_ref (gfc_expr *e);
 gfc_expr *gfc_class_initializer (gfc_typespec *, gfc_expr *);
 unsigned int gfc_hash_value (gfc_symbol *);
+gfc_expr *gfc_get_len_component (gfc_expr *e);
 bool gfc_build_class_symbol (gfc_typespec *, symbol_attribute *,
 			     gfc_array_spec **);
 gfc_symbol *gfc_find_derived_vtab (gfc_symbol *);
Index: gcc/fortran/ChangeLog
===================================================================
--- gcc/fortran/ChangeLog	(Revision 221590)
+++ gcc/fortran/ChangeLog	(Arbeitskopie)
@@ -1,3 +1,28 @@
+2015-03-23  Andre Vehreschild  <ve...@gmx.de>
+	    Janus Weil  <ja...@gcc.gnu.org>
+
+	Backported from mainline
+	PR fortran/60255
+	Initial patch version: Janus Weil
+	* class.c (gfc_get_len_component): New.
+	(gfc_build_class_symbol): Add _len component to unlimited
+	polymorphic entities.
+	(find_intrinsic_vtab): Removed emitting of error message.
+	* gfortran.h: Added prototype for gfc_get_len_component.
+	* simplify.c (gfc_simplify_len): Use _len component where
+	available.
+	* trans-expr.c (gfc_class_len_get): New.
+	(gfc_conv_intrinsic_to_class): Add handling for deferred
+	character arrays.
+	(gfc_conv_structure): Treat _len component correctly.
+	(gfc_conv_expr): Prevent bind_c handling when not required.
+	(gfc_trans_pointer_assignment): Propagate _len component.
+	* trans-stmt.c (class_has_len_component): New.
+	(trans_associate_var): _len component treatement for associate
+	context.
+	(gfc_trans_allocate): Same as for trans_associate_var()
+	* trans.h: Add prototype for gfc_class_len_get.
+
 2015-03-21  Mikael Morin  <mik...@gcc.gnu.org>
 
 	PR fortran/61138
Index: gcc/fortran/trans-stmt.c
===================================================================
--- gcc/fortran/trans-stmt.c	(Revision 221590)
+++ gcc/fortran/trans-stmt.c	(Arbeitskopie)
@@ -1133,6 +1133,22 @@
 }
 
 
+/* Return true, when the class has a _len component.  */
+
+static bool
+class_has_len_component (gfc_symbol *sym)
+{
+  gfc_component *comp = sym->ts.u.derived->components;
+  while (comp)
+    {
+      if (strcmp (comp->name, "_len") == 0)
+	return true;
+      comp = comp->next;
+    }
+  return false;
+}
+
+
 /* Do proper initialization for ASSOCIATE names.  */
 
 static void
@@ -1146,6 +1162,8 @@
   tree offset;
   tree dim;
   int n;
+  tree charlen;
+  bool need_len_assign;
 
   gcc_assert (sym->assoc);
   e = sym->assoc->target;
@@ -1156,6 +1174,20 @@
 
   unlimited = UNLIMITED_POLY (e);
 
+  /* Assignments to the string length need to be generated, when
+     ( sym is a char array or
+       sym has a _len component)
+     and the associated expression is unlimited polymorphic, which is
+     not (yet) correctly in 'unlimited', because for an already associated
+     BT_DERIVED the u-poly flag is not set, i.e.,
+      __tmp_CHARACTER_0_1 => w => arg
+       ^ generated temp      ^ from code, the w does not have the u-poly
+     flag set, where UNLIMITED_POLY(e) expects it.  */
+  need_len_assign = ((unlimited || (e->ts.type == BT_DERIVED
+                     && e->ts.u.derived->attr.unlimited_polymorphic))
+      && (sym->ts.type == BT_CHARACTER
+          || ((sym->ts.type == BT_CLASS || sym->ts.type == BT_DERIVED)
+              && class_has_len_component (sym))));
   /* Do a `pointer assignment' with updated descriptor (or assign descriptor
      to array temporary) for arrays with either unknown shape or if associating
      to a variable.  */
@@ -1255,8 +1287,11 @@
 	 unconditionally associate pointers and the symbol is scalar.  */
       if (sym->ts.type == BT_CLASS && CLASS_DATA (sym)->attr.dimension)
 	{
+	  tree target_expr;
 	  /* For a class array we need a descriptor for the selector.  */
 	  gfc_conv_expr_descriptor (&se, e);
+	  /* Needed to get/set the _len component below.  */
+	  target_expr = se.expr;
 
 	  /* Obtain a temporary class container for the result.  */
 	  gfc_conv_class_to_class (&se, e, sym->ts, false, true, false, false);
@@ -1276,6 +1311,23 @@
 				        gfc_array_index_type,
 				        offset, tmp);
 	    }
+	  if (need_len_assign)
+	    {
+	      /* Get the _len comp from the target expr by stripping _data
+		 from it and adding component-ref to _len.  */
+	      tmp = gfc_class_len_get (TREE_OPERAND (target_expr, 0));
+	      /* Get the component-ref for the temp structure's _len comp.  */
+	      charlen = gfc_class_len_get (se.expr);
+	      /* Add the assign to the beginning of the the block...  */
+	      gfc_add_modify (&se.pre, charlen,
+			      fold_convert (TREE_TYPE (charlen), tmp));
+	      /* and the oposite way at the end of the block, to hand changes
+		 on the string length back.  */
+	      gfc_add_modify (&se.post, tmp,
+			      fold_convert (TREE_TYPE (tmp), charlen));
+	      /* Length assignment done, prevent adding it again below.  */
+	      need_len_assign = false;
+	    }
 	  gfc_conv_descriptor_offset_set (&se.pre, desc, offset);
 	}
       else if (sym->ts.type == BT_CLASS && e->ts.type == BT_CLASS
@@ -1290,7 +1342,13 @@
 	  se.expr = build_fold_indirect_ref_loc (input_location, se.expr);
 	}
       else
-	gfc_conv_expr (&se, e);
+	{
+	  /* For BT_CLASS and BT_DERIVED, this boils down to a pointer assign,
+	     which has the string length included.  For CHARACTERS it is still
+	     needed and will be done at the end of this routine.  */
+	  gfc_conv_expr (&se, e);
+	  need_len_assign = need_len_assign && sym->ts.type == BT_CHARACTER;
+	}
 
       tmp = TREE_TYPE (sym->backend_decl);
       tmp = gfc_build_addr_expr (tmp, se.expr);
@@ -1311,21 +1369,30 @@
       gfc_add_init_cleanup (block, tmp, NULL_TREE);
     }
 
-  /* Set the stringlength from the vtable size.  */
-  if (sym->ts.type == BT_CHARACTER && sym->attr.select_type_temporary)
+  /* Set the stringlength, when needed.  */
+  if (need_len_assign)
     {
-      tree charlen;
       gfc_se se;
       gfc_init_se (&se, NULL);
-      gcc_assert (UNLIMITED_POLY (e->symtree->n.sym));
-      tmp = gfc_get_symbol_decl (e->symtree->n.sym);
-      tmp = gfc_vtable_size_get (tmp);
+      if (e->symtree->n.sym->ts.type == BT_CHARACTER)
+	{
+	  /* What about deferred strings?  */
+	  gcc_assert (!e->symtree->n.sym->ts.deferred);
+	  tmp = e->symtree->n.sym->ts.u.cl->backend_decl;
+	}
+      else
+	tmp = gfc_class_len_get (gfc_get_symbol_decl (e->symtree->n.sym));
       gfc_get_symbol_decl (sym);
-      charlen = sym->ts.u.cl->backend_decl;
-      gfc_add_modify (&se.pre, charlen,
-		      fold_convert (TREE_TYPE (charlen), tmp));
-      gfc_add_init_cleanup (block, gfc_finish_block( &se.pre),
-			    gfc_finish_block (&se.post));
+      charlen = sym->ts.type == BT_CHARACTER ? sym->ts.u.cl->backend_decl
+					: gfc_class_len_get (sym->backend_decl);
+      /* Prevent adding a noop len= len.  */
+      if (tmp != charlen)
+	{
+	  gfc_add_modify (&se.pre, charlen,
+			  fold_convert (TREE_TYPE (charlen), tmp));
+	  gfc_add_init_cleanup (block, gfc_finish_block (&se.pre),
+				gfc_finish_block (&se.post));
+	}
     }
 }
 
@@ -5038,6 +5105,15 @@
 		gfc_add_modify (&se.pre, se.string_length,
 				fold_convert (TREE_TYPE (se.string_length),
 				memsz));
+	      else if ((al->expr->ts.type == BT_DERIVED
+			|| al->expr->ts.type == BT_CLASS)
+		       && expr->ts.u.derived->attr.unlimited_polymorphic)
+		{
+		  tmp = gfc_class_len_get (al->expr->symtree->n.sym->backend_decl);
+		  gfc_add_modify (&se.pre, tmp,
+				  fold_convert (TREE_TYPE (tmp),
+						memsz));
+		}
 
 	      /* Convert to size in bytes, using the character KIND.  */
 	      if (unlimited_char)
Index: gcc/fortran/trans.h
===================================================================
--- gcc/fortran/trans.h	(Revision 221590)
+++ gcc/fortran/trans.h	(Arbeitskopie)
@@ -347,6 +347,7 @@
 /* Class API functions.  */
 tree gfc_class_data_get (tree);
 tree gfc_class_vptr_get (tree);
+tree gfc_class_len_get (tree);
 void gfc_reset_vptr (stmtblock_t *, gfc_expr *);
 tree gfc_class_set_static_fields (tree, tree, tree);
 tree gfc_vtable_hash_get (tree);

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