re PR fortran/18918 (Eventually support Fortran 2008's coarrays [co-arrays])

2010-04-09  Tobias Burnus  <burnus@net-b.de>

        PR fortran/18918
        * decl.c (variable_decl, match_attr_spec): Fix setting the array
        spec.
        * array.c (match_subscript,gfc_match_array_ref): Add coarray
        * support.
        * data.c (gfc_assign_data_value): Ditto.
        * expr.c (gfc_check_pointer_assign): Add check for coarray
        * constraint.
        (gfc_traverse_expr): Traverse also through codimension expressions.
        (gfc_is_coindexed, gfc_has_ultimate_allocatable,
        gfc_has_ultimate_pointer): New functions.
        * gfortran.h (gfc_array_ref_dimen_type): Add DIMEN_STAR for
        * coarrays.
        (gfc_array_ref): Add codimen.
        (gfc_array_ref): Add in_allocate.
        (gfc_is_coindexed, gfc_has_ultimate_allocatable,
        gfc_has_ultimate_pointer): Add prototypes.
        * interface.c (compare_parameter, compare_actual_formal,
        check_intents): Add coarray constraints.
        * match.c (gfc_match_iterator): Add coarray constraint.
        * match.h (gfc_match_array_ref): Update interface.
        * primary.c (gfc_match_varspec): Handle codimensions.
        * resolve.c (coarray_alloc, inquiry_argument): New static
        * variables.
        (check_class_members): Return gfc_try instead for error recovery.
        (resolve_typebound_function,resolve_typebound_subroutine,
        check_members): Handle return value of check_class_members.
        (resolve_structure_cons, resolve_actual_arglist, resolve_function,
        check_dimension, compare_spec_to_ref, resolve_array_ref,
        resolve_ref, resolve_variable, gfc_resolve_expr, conformable_arrays,
        resolve_allocate_expr, resolve_ordinary_assign): Add coarray
        support.
        * trans-array.c (gfc_conv_array_ref, gfc_walk_variable_expr):
        Skip over coarray refs.
        (gfc_array_allocate) Add support for references containing coindexes.
        * trans-expr.c (gfc_add_interface_mapping): Copy coarray
        * attribute.
        (gfc_map_intrinsic_function): Ignore codimensions.

2010-04-09  Tobias Burnus  <burnus@net-b.de>

        PR fortran/18918
        * gfortran.dg/coarray_7.f90: New test.
        * gfortran.dg/coarray_8.f90: New test.

From-SVN: r158149

13 files changed, 821 insertions, 93 deletions

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index 0b6bfae..96efee0 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,39 @@
+2010-04-09  Tobias Burnus  <burnus@net-b.de>
+
+	PR fortran/18918
+	* decl.c (variable_decl, match_attr_spec): Fix setting the array
+	spec.
+	* array.c (match_subscript,gfc_match_array_ref): Add coarray support.
+	* data.c (gfc_assign_data_value): Ditto.
+	* expr.c (gfc_check_pointer_assign): Add check for coarray constraint.
+	(gfc_traverse_expr): Traverse also through codimension expressions.
+	(gfc_is_coindexed, gfc_has_ultimate_allocatable,
+	gfc_has_ultimate_pointer): New functions.
+	* gfortran.h (gfc_array_ref_dimen_type): Add DIMEN_STAR for coarrays.
+	(gfc_array_ref): Add codimen.
+	(gfc_array_ref): Add in_allocate.
+	(gfc_is_coindexed, gfc_has_ultimate_allocatable,
+	gfc_has_ultimate_pointer): Add prototypes.
+	* interface.c (compare_parameter, compare_actual_formal,
+	check_intents): Add coarray constraints.
+	* match.c (gfc_match_iterator): Add coarray constraint.
+	* match.h (gfc_match_array_ref): Update interface.
+	* primary.c (gfc_match_varspec): Handle codimensions.
+	* resolve.c (coarray_alloc, inquiry_argument): New static variables.
+	(check_class_members): Return gfc_try instead for error recovery.
+	(resolve_typebound_function,resolve_typebound_subroutine,
+	check_members): Handle return value of check_class_members.
+	(resolve_structure_cons, resolve_actual_arglist, resolve_function,
+	check_dimension, compare_spec_to_ref, resolve_array_ref,
+	resolve_ref, resolve_variable, gfc_resolve_expr, conformable_arrays,
+	resolve_allocate_expr, resolve_ordinary_assign): Add coarray
+	support.
+	* trans-array.c (gfc_conv_array_ref, gfc_walk_variable_expr):
+	Skip over coarray refs.
+	(gfc_array_allocate) Add support for references containing coindexes.
+	* trans-expr.c (gfc_add_interface_mapping): Copy coarray attribute.
+	(gfc_map_intrinsic_function): Ignore codimensions.
+
 2010-04-08  Bud Davis  <bdavis9659@sbcglobal.net>
 
 	PR fortran/28039
diff --git a/gcc/fortran/array.c b/gcc/fortran/array.c
index 4282fd1..5ceca4b 100644
--- a/gcc/fortran/array.c
+++ b/gcc/fortran/array.c
@@ -61,12 +61,13 @@ gfc_copy_array_ref (gfc_array_ref *src)
    expression.  */
 
 static match
-match_subscript (gfc_array_ref *ar, int init)
+match_subscript (gfc_array_ref *ar, int init, bool match_star)
 {
   match m;
+  bool star = false;
   int i;
 
-  i = ar->dimen;
+  i = ar->dimen + ar->codimen;
 
   ar->c_where[i] = gfc_current_locus;
   ar->start[i] = ar->end[i] = ar->stride[i] = NULL;
@@ -81,9 +82,12 @@ match_subscript (gfc_array_ref *ar, int init)
     goto end_element;
 
   /* Get start element.  */
-  if (init)
+  if (match_star && (m = gfc_match_char ('*')) == MATCH_YES)
+    star = true;
+
+  if (!star && init)
     m = gfc_match_init_expr (&ar->start[i]);
-  else
+  else if (!star)
     m = gfc_match_expr (&ar->start[i]);
 
   if (m == MATCH_NO)
@@ -92,14 +96,22 @@ match_subscript (gfc_array_ref *ar, int init)
     return MATCH_ERROR;
 
   if (gfc_match_char (':') == MATCH_NO)
-    return MATCH_YES;
+    goto matched;
+
+  if (star)
+    {
+      gfc_error ("Unexpected '*' in coarray subscript at %C");
+      return MATCH_ERROR;
+    }
 
   /* Get an optional end element.  Because we've seen the colon, we
      definitely have a range along this dimension.  */
 end_element:
   ar->dimen_type[i] = DIMEN_RANGE;
 
-  if (init)
+  if (match_star && (m = gfc_match_char ('*')) == MATCH_YES)
+    star = true;
+  else if (init)
     m = gfc_match_init_expr (&ar->end[i]);
   else
     m = gfc_match_expr (&ar->end[i]);
@@ -110,6 +122,12 @@ end_element:
   /* See if we have an optional stride.  */
   if (gfc_match_char (':') == MATCH_YES)
     {
+      if (star)
+	{
+	  gfc_error ("Strides not allowed in coarray subscript at %C");
+	  return MATCH_ERROR;
+	}
+
       m = init ? gfc_match_init_expr (&ar->stride[i])
 	       : gfc_match_expr (&ar->stride[i]);
 
@@ -119,6 +137,10 @@ end_element:
 	return MATCH_ERROR;
     }
 
+matched:
+  if (star)
+    ar->dimen_type[i] = DIMEN_STAR;
+
   return MATCH_YES;
 }
 
@@ -128,14 +150,23 @@ end_element:
    to consist of init expressions.  */
 
 match
-gfc_match_array_ref (gfc_array_ref *ar, gfc_array_spec *as, int init)
+gfc_match_array_ref (gfc_array_ref *ar, gfc_array_spec *as, int init,
+		     int corank)
 {
   match m;
+  bool matched_bracket = false;
 
   memset (ar, '\0', sizeof (ar));
 
   ar->where = gfc_current_locus;
   ar->as = as;
+  ar->type = AR_UNKNOWN;
+
+  if (gfc_match_char ('[') == MATCH_YES)
+    {
+       matched_bracket = true;
+       goto coarray;
+    }
 
   if (gfc_match_char ('(') != MATCH_YES)
     {
@@ -144,34 +175,73 @@ gfc_match_array_ref (gfc_array_ref *ar, gfc_array_spec *as, int init)
       return MATCH_YES;
     }
 
-  ar->type = AR_UNKNOWN;
-
   for (ar->dimen = 0; ar->dimen < GFC_MAX_DIMENSIONS; ar->dimen++)
     {
-      m = match_subscript (ar, init);
+      m = match_subscript (ar, init, false);
       if (m == MATCH_ERROR)
-	goto error;
+	return MATCH_ERROR;
 
       if (gfc_match_char (')') == MATCH_YES)
-	goto matched;
+	{
+	  ar->dimen++;
+	  goto coarray;
+	}
 
       if (gfc_match_char (',') != MATCH_YES)
 	{
 	  gfc_error ("Invalid form of array reference at %C");
-	  goto error;
+	  return MATCH_ERROR;
 	}
     }
 
   gfc_error ("Array reference at %C cannot have more than %d dimensions",
 	     GFC_MAX_DIMENSIONS);
-
-error:
   return MATCH_ERROR;
 
-matched:
-  ar->dimen++;
+coarray:
+  if (!matched_bracket && gfc_match_char ('[') != MATCH_YES)
+    {
+      if (ar->dimen > 0)
+	return MATCH_YES;
+      else
+	return MATCH_ERROR;
+    }
+
+  if (gfc_option.coarray == GFC_FCOARRAY_NONE)
+    {
+      gfc_error ("Coarrays disabled at %C, use -fcoarray= to enable");
+      return MATCH_ERROR;
+    }
+
+  if (corank == 0)
+    {
+	gfc_error ("Unexpected coarray designator at %C");
+	return MATCH_ERROR;
+    }
+
+  for (ar->codimen = 0; ar->codimen + ar->dimen < GFC_MAX_DIMENSIONS; ar->codimen++)
+    {
+      m = match_subscript (ar, init, ar->codimen == (corank - 1));
+      if (m == MATCH_ERROR)
+	return MATCH_ERROR;
+
+      if (gfc_match_char (']') == MATCH_YES)
+	{
+	  ar->codimen++;
+	  return MATCH_YES;
+	}
+
+      if (gfc_match_char (',') != MATCH_YES)
+	{
+	  gfc_error ("Invalid form of coarray reference at %C");
+	  return MATCH_ERROR;
+	}
+    }
+
+  gfc_error ("Array reference at %C cannot have more than %d dimensions",
+	     GFC_MAX_DIMENSIONS);
+  return MATCH_ERROR;
 
-  return MATCH_YES;
 }
 
 
@@ -460,8 +530,8 @@ coarray:
 
   if (gfc_option.coarray == GFC_FCOARRAY_NONE)
     {
-       gfc_error ("Coarrays disabled at %C, use -fcoarray= to enable");
-       goto cleanup;
+      gfc_error ("Coarrays disabled at %C, use -fcoarray= to enable");
+      goto cleanup;
     }
 
   for (;;)
diff --git a/gcc/fortran/data.c b/gcc/fortran/data.c
index 0d04d65..16cd899 100644
--- a/gcc/fortran/data.c
+++ b/gcc/fortran/data.c
@@ -289,6 +289,14 @@ gfc_assign_data_value (gfc_expr *lvalue, gfc_expr *rvalue, mpz_t index)
       switch (ref->type)
 	{
 	case REF_ARRAY:
+	  if (ref->u.ar.as->rank == 0)
+	    {
+	      gcc_assert (ref->u.ar.as->corank > 0);
+	      if (init == NULL)
+		gfc_free (expr);
+	      continue;
+	    }
+
 	  if (init && expr->expr_type != EXPR_ARRAY)
 	    {
 	      gfc_error ("'%s' at %L already is initialized at %L",
diff --git a/gcc/fortran/decl.c b/gcc/fortran/decl.c
index b376192..a9cd984 100644
--- a/gcc/fortran/decl.c
+++ b/gcc/fortran/decl.c
@@ -570,6 +570,62 @@ cleanup:
 
 /************************ Declaration statements *********************/
 
+
+/* Auxilliary function to merge DIMENSION and CODIMENSION array specs.  */
+
+static void
+merge_array_spec (gfc_array_spec *from, gfc_array_spec *to, bool copy)
+{
+  int i;
+
+  if (to->rank == 0 && from->rank > 0)
+    {
+      to->rank = from->rank;
+      to->type = from->type;
+      to->cray_pointee = from->cray_pointee;
+      to->cp_was_assumed = from->cp_was_assumed;
+
+      for (i = 0; i < to->corank; i++)
+	{
+	  to->lower[from->rank + i] = to->lower[i];
+	  to->upper[from->rank + i] = to->upper[i];
+	}
+      for (i = 0; i < from->rank; i++)
+	{
+	  if (copy)
+	    {
+	      to->lower[i] = gfc_copy_expr (from->lower[i]);
+	      to->upper[i] = gfc_copy_expr (from->upper[i]);
+	    }
+	  else
+	    {
+	      to->lower[i] = from->lower[i];
+	      to->upper[i] = from->upper[i];
+	    }
+	}
+    }
+  else if (to->corank == 0 && from->corank > 0)
+    {
+      to->corank = from->corank;
+      to->cotype = from->cotype;
+
+      for (i = 0; i < from->corank; i++)
+	{
+	  if (copy)
+	    {
+	      to->lower[to->rank + i] = gfc_copy_expr (from->lower[i]);
+	      to->upper[to->rank + i] = gfc_copy_expr (from->upper[i]);
+	    }
+	  else
+	    {
+	      to->lower[to->rank + i] = from->lower[i];
+	      to->upper[to->rank + i] = from->upper[i];
+	    }
+	}
+    }
+}
+
+
 /* Match an intent specification.  Since this can only happen after an
    INTENT word, a legal intent-spec must follow.  */
 
@@ -1603,6 +1659,8 @@ variable_decl (int elem)
 
   if (m == MATCH_NO)
     as = gfc_copy_array_spec (current_as);
+  else if (current_as)
+    merge_array_spec (current_as, as, true);
 
   char_len = NULL;
   cl = NULL;
@@ -3050,27 +3108,27 @@ match_attr_spec (void)
       seen[d]++;
       seen_at[d] = gfc_current_locus;
 
-      if (d == DECL_DIMENSION)
+      if (d == DECL_DIMENSION || d == DECL_CODIMENSION)
 	{
-	  m = gfc_match_array_spec (&current_as, true, false);
+	  gfc_array_spec *as = NULL;
 
-	  if (m == MATCH_NO)
+	  m = gfc_match_array_spec (&as, d == DECL_DIMENSION,
+				    d == DECL_CODIMENSION);
+
+	  if (current_as == NULL)
+	    current_as = as;
+	  else if (m == MATCH_YES)
 	    {
-	      gfc_error ("Missing dimension specification at %C");
-	      m = MATCH_ERROR;
+	      merge_array_spec (as, current_as, false);
+	      gfc_free (as);
 	    }
 
-	  if (m == MATCH_ERROR)
-	    goto cleanup;
-	}
-
-      if (d == DECL_CODIMENSION)
-	{
-	  m = gfc_match_array_spec (&current_as, false, true);
-
 	  if (m == MATCH_NO)
 	    {
-	      gfc_error ("Missing codimension specification at %C");
+	      if (d == DECL_CODIMENSION)
+		gfc_error ("Missing codimension specification at %C");
+	      else
+		gfc_error ("Missing dimension specification at %C");
 	      m = MATCH_ERROR;
 	    }
 
diff --git a/gcc/fortran/expr.c b/gcc/fortran/expr.c
index d85f23c..2200a80 100644
--- a/gcc/fortran/expr.c
+++ b/gcc/fortran/expr.c
@@ -3205,6 +3205,20 @@ gfc_check_pointer_assign (gfc_expr *lvalue, gfc_expr *rvalue)
   if (rvalue->expr_type == EXPR_NULL && rvalue->ts.type == BT_UNKNOWN)
     return SUCCESS;
 
+  /* F2008, C723 (pointer) and C726 (proc-pointer); for PURE also C1283.  */
+  if (lvalue->expr_type == EXPR_VARIABLE
+      && gfc_is_coindexed (lvalue))
+    {
+      gfc_ref *ref;
+      for (ref = lvalue->ref; ref; ref = ref->next)
+	if (ref->type == REF_ARRAY && ref->u.ar.codimen)
+	  {
+	    gfc_error ("Pointer object at %L shall not have a coindex",
+		       &lvalue->where);
+	    return FAILURE;
+	  }
+    }
+
   /* Checks on rvalue for procedure pointer assignments.  */
   if (proc_pointer)
     {
@@ -3369,6 +3383,20 @@ gfc_check_pointer_assign (gfc_expr *lvalue, gfc_expr *rvalue)
       return FAILURE;
     }
 
+  /* F2008, C725. For PURE also C1283.  */
+  if (rvalue->expr_type == EXPR_VARIABLE
+      && gfc_is_coindexed (rvalue))
+    {
+      gfc_ref *ref;
+      for (ref = rvalue->ref; ref; ref = ref->next)
+	if (ref->type == REF_ARRAY && ref->u.ar.codimen)
+	  {
+	    gfc_error ("Data target at %L shall not have a coindex",
+		       &rvalue->where);
+	    return FAILURE;
+	  }
+    }
+
   return SUCCESS;
 }
 
@@ -3642,7 +3670,8 @@ gfc_traverse_expr (gfc_expr *expr, gfc_symbol *sym,
 	    return true;
 
 	  if (ref->u.c.component->as)
-	    for (i = 0; i < ref->u.c.component->as->rank; i++)
+	    for (i = 0; i < ref->u.c.component->as->rank
+			    + ref->u.c.component->as->corank; i++)
 	      {
 		if (gfc_traverse_expr (ref->u.c.component->as->lower[i],
 				       sym, func, f))
@@ -3836,3 +3865,75 @@ gfc_expr_replace_comp (gfc_expr *expr, gfc_component *dest)
   gfc_traverse_expr (expr, (gfc_symbol *)dest, &replace_comp, 0);
 }
 
+
+bool
+gfc_is_coindexed (gfc_expr *e)
+{
+  gfc_ref *ref;
+
+  for (ref = e->ref; ref; ref = ref->next)
+    if (ref->type == REF_ARRAY && ref->u.ar.codimen > 0)
+      return true;
+
+  return false;
+}
+
+
+/* Check whether the expression has an ultimate allocatable component.
+   Being itself allocatable does not count.  */
+bool
+gfc_has_ultimate_allocatable (gfc_expr *e)
+{
+  gfc_ref *ref, *last = NULL;
+
+  if (e->expr_type != EXPR_VARIABLE)
+    return false;
+
+  for (ref = e->ref; ref; ref = ref->next)
+    if (ref->type == REF_COMPONENT)
+      last = ref;
+
+  if (last && last->u.c.component->ts.type == BT_CLASS)
+    return last->u.c.component->ts.u.derived->components->attr.alloc_comp;
+  else if (last && last->u.c.component->ts.type == BT_DERIVED)
+    return last->u.c.component->ts.u.derived->attr.alloc_comp;
+  else if (last)
+    return false;
+
+  if (e->ts.type == BT_CLASS)
+    return e->ts.u.derived->components->attr.alloc_comp;
+  else if (e->ts.type == BT_DERIVED)
+    return e->ts.u.derived->attr.alloc_comp;
+  else
+    return false;
+}
+
+
+/* Check whether the expression has an pointer component.
+   Being itself a pointer does not count.  */
+bool
+gfc_has_ultimate_pointer (gfc_expr *e)
+{
+  gfc_ref *ref, *last = NULL;
+
+  if (e->expr_type != EXPR_VARIABLE)
+    return false;
+
+  for (ref = e->ref; ref; ref = ref->next)
+    if (ref->type == REF_COMPONENT)
+      last = ref;
+ 
+  if (last && last->u.c.component->ts.type == BT_CLASS)
+    return last->u.c.component->ts.u.derived->components->attr.pointer_comp;
+  else if (last && last->u.c.component->ts.type == BT_DERIVED)
+    return last->u.c.component->ts.u.derived->attr.pointer_comp;
+  else if (last)
+    return false;
+
+  if (e->ts.type == BT_CLASS)
+    return e->ts.u.derived->components->attr.pointer_comp;
+  else if (e->ts.type == BT_DERIVED)
+    return e->ts.u.derived->attr.pointer_comp;
+  else
+    return false;
+}
diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index f4f5d52..3668df4 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -1444,13 +1444,15 @@ extern gfc_interface_info current_interface;
 
 enum gfc_array_ref_dimen_type
 {
-  DIMEN_ELEMENT = 1, DIMEN_RANGE, DIMEN_VECTOR, DIMEN_UNKNOWN
+  DIMEN_ELEMENT = 1, DIMEN_RANGE, DIMEN_VECTOR, DIMEN_STAR, DIMEN_UNKNOWN
 };
 
 typedef struct gfc_array_ref
 {
   ar_type type;
   int dimen;			/* # of components in the reference */
+  int codimen;
+  bool in_allocate;		/* For coarray checks. */
   locus where;
   gfc_array_spec *as;
 
@@ -2642,6 +2644,11 @@ void gfc_expr_replace_comp (gfc_expr *, gfc_component *);
 
 bool gfc_is_proc_ptr_comp (gfc_expr *, gfc_component **);
 
+bool gfc_is_coindexed (gfc_expr *);
+bool gfc_has_ultimate_allocatable (gfc_expr *);
+bool gfc_has_ultimate_pointer (gfc_expr *);
+
+
 /* st.c */
 extern gfc_code new_st;
 
diff --git a/gcc/fortran/interface.c b/gcc/fortran/interface.c
index 5b01af9..9dd797b 100644
--- a/gcc/fortran/interface.c
+++ b/gcc/fortran/interface.c
@@ -1445,6 +1445,65 @@ compare_parameter (gfc_symbol *formal, gfc_expr *actual,
       return 0;
     }
 
+  if (formal->attr.codimension)
+    {
+      gfc_ref *last = NULL;
+
+      if (actual->expr_type != EXPR_VARIABLE
+	  || (actual->ref == NULL
+	      && !actual->symtree->n.sym->attr.codimension))
+	{
+	  if (where)
+	    gfc_error ("Actual argument to '%s' at %L must be a coarray",
+		       formal->name, &actual->where);
+	  return 0;
+	}
+
+      for (ref = actual->ref; ref; ref = ref->next)
+	{
+	  if (ref->type == REF_ARRAY && ref->u.ar.codimen != 0)
+	    {
+	      if (where)
+		gfc_error ("Actual argument to '%s' at %L must be a coarray "
+			   "and not coindexed", formal->name, &ref->u.ar.where);
+	      return 0;
+	    }
+	  if (ref->type == REF_ARRAY && ref->u.ar.as->corank
+	      && ref->u.ar.type != AR_FULL && ref->u.ar.dimen != 0)
+	    {
+	      if (where)
+		gfc_error ("Actual argument to '%s' at %L must be a coarray "
+			   "and thus shall not have an array designator",
+			   formal->name, &ref->u.ar.where);
+	      return 0;
+	    }
+	  if (ref->type == REF_COMPONENT)
+	    last = ref;
+	}
+
+      if (last && !last->u.c.component->attr.codimension)
+      	{
+	  if (where)
+	    gfc_error ("Actual argument to '%s' at %L must be a coarray",
+		       formal->name, &actual->where);
+	  return 0;
+	}
+
+      /* F2008, 12.5.2.6.  */
+      if (formal->attr.allocatable &&
+	  ((last && last->u.c.component->as->corank != formal->as->corank)
+	   || (!last
+	       && actual->symtree->n.sym->as->corank != formal->as->corank)))
+	{
+	  if (where)
+	    gfc_error ("Corank mismatch in argument '%s' at %L (%d and %d)",
+		   formal->name, &actual->where, formal->as->corank,
+		   last ? last->u.c.component->as->corank
+			: actual->symtree->n.sym->as->corank);
+	  return 0;
+	}
+    }
+
   if (symbol_rank (formal) == actual->rank)
     return 1;
 
@@ -1453,10 +1512,13 @@ compare_parameter (gfc_symbol *formal, gfc_expr *actual,
 		   || formal->as->type == AS_DEFERRED)
 	       && actual->expr_type != EXPR_NULL;
 
+  /* Scalar & coindexed, see: F2008, Section 12.5.2.4.  */
   if (rank_check || ranks_must_agree
       || (formal->attr.pointer && actual->expr_type != EXPR_NULL)
       || (actual->rank != 0 && !(is_elemental || formal->attr.dimension))
-      || (actual->rank == 0 && formal->as->type == AS_ASSUMED_SHAPE))
+      || (actual->rank == 0 && formal->as->type == AS_ASSUMED_SHAPE)
+      || (actual->rank == 0 && formal->attr.dimension
+	  && gfc_is_coindexed (actual)))
     {
       if (where)
 	gfc_error ("Rank mismatch in argument '%s' at %L (%d and %d)",
@@ -1474,7 +1536,8 @@ compare_parameter (gfc_symbol *formal, gfc_expr *actual,
      - (F2003) if the actual argument is of type character.  */
 
   for (ref = actual->ref; ref; ref = ref->next)
-    if (ref->type == REF_ARRAY && ref->u.ar.type == AR_ELEMENT)
+    if (ref->type == REF_ARRAY && ref->u.ar.type == AR_ELEMENT
+	&& ref->u.ar.dimen > 0)
       break;
 
   /* Not an array element.  */
@@ -1984,6 +2047,57 @@ compare_actual_formal (gfc_actual_arglist **ap, gfc_formal_arglist *formal,
 	  return 0;
 	}
 
+      /* Fortran 2008, C1242.  */
+      if (f->sym->attr.pointer && gfc_is_coindexed (a->expr))
+	{
+	  if (where)
+	    gfc_error ("Coindexed actual argument at %L to pointer "
+		       "dummy '%s'",
+		       &a->expr->where, f->sym->name);
+	  return 0;
+	}
+
+      /* Fortran 2008, 12.5.2.5 (no constraint).  */
+      if (a->expr->expr_type == EXPR_VARIABLE
+	  && f->sym->attr.intent != INTENT_IN
+	  && f->sym->attr.allocatable
+	  && gfc_is_coindexed (a->expr))
+	{
+	  if (where)
+	    gfc_error ("Coindexed actual argument at %L to allocatable "
+		       "dummy '%s' requires INTENT(IN)",
+		       &a->expr->where, f->sym->name);
+	  return 0;
+	}
+
+      /* Fortran 2008, C1237.  */
+      if (a->expr->expr_type == EXPR_VARIABLE
+	  && (f->sym->attr.asynchronous || f->sym->attr.volatile_)
+	  && gfc_is_coindexed (a->expr)
+	  && (a->expr->symtree->n.sym->attr.volatile_
+	      || a->expr->symtree->n.sym->attr.asynchronous))
+	{
+	  if (where)
+	    gfc_error ("Coindexed ASYNCHRONOUS or VOLATILE actual argument at "
+		       "at %L requires that dummy %s' has neither "
+		       "ASYNCHRONOUS nor VOLATILE", &a->expr->where,
+		       f->sym->name);
+	  return 0;
+	}
+
+      /* Fortran 2008, 12.5.2.4 (no constraint).  */
+      if (a->expr->expr_type == EXPR_VARIABLE
+	  && f->sym->attr.intent != INTENT_IN && !f->sym->attr.value
+	  && gfc_is_coindexed (a->expr)
+	  && gfc_has_ultimate_allocatable (a->expr))
+	{
+	  if (where)
+	    gfc_error ("Coindexed actual argument at %L with allocatable "
+		       "ultimate component to dummy '%s' requires either VALUE "
+		       "or INTENT(IN)", &a->expr->where, f->sym->name);
+	  return 0;
+	}
+
       if (a->expr->expr_type != EXPR_NULL
 	  && compare_allocatable (f->sym, a->expr) == 0)
 	{
@@ -2367,6 +2481,36 @@ check_intents (gfc_formal_arglist *f, gfc_actual_arglist *a)
 	      return FAILURE;
 	    }
 	}
+
+       /* Fortran 2008, C1283.  */
+       if (gfc_pure (NULL) && gfc_is_coindexed (a->expr))
+	{
+	  if (f_intent == INTENT_INOUT || f_intent == INTENT_OUT)
+	    {
+	      gfc_error ("Coindexed actual argument at %L in PURE procedure "
+			 "is passed to an INTENT(%s) argument",
+			 &a->expr->where, gfc_intent_string (f_intent));
+	      return FAILURE;
+	    }
+
+	  if (f->sym->attr.pointer)
+	    {
+	      gfc_error ("Coindexed actual argument at %L in PURE procedure "
+			 "is passed to a POINTER dummy argument",
+			 &a->expr->where);
+	      return FAILURE;
+	    }
+	}
+
+       /* F2008, Section 12.5.2.4.  */
+       if (a->expr->ts.type == BT_CLASS && f->sym->ts.type == BT_CLASS
+	   && gfc_is_coindexed (a->expr))
+	 {
+	   gfc_error ("Coindexed polymorphic actual argument at %L is passed "
+		      "polymorphic dummy argument '%s'",
+			 &a->expr->where, f->sym->name);
+	   return FAILURE;
+	 }
     }
 
   return SUCCESS;
diff --git a/gcc/fortran/match.c b/gcc/fortran/match.c
index 70bf9ac..2709de7 100644
--- a/gcc/fortran/match.c
+++ b/gcc/fortran/match.c
@@ -949,6 +949,8 @@ gfc_match_iterator (gfc_iterator *iter, int init_flag)
   locus start;
   match m;
 
+  e1 = e2 = e3 = NULL;
+
   /* Match the start of an iterator without affecting the symbol table.  */
 
   start = gfc_current_locus;
@@ -962,9 +964,12 @@ gfc_match_iterator (gfc_iterator *iter, int init_flag)
   if (m != MATCH_YES)
     return MATCH_NO;
 
-  gfc_match_char ('=');
-
-  e1 = e2 = e3 = NULL;
+  /* F2008, C617 & C565.  */
+  if (var->symtree->n.sym->attr.codimension)
+    {
+      gfc_error ("Loop variable at %C cannot be a coarray");
+      goto cleanup;
+    }
 
   if (var->ref != NULL)
     {
@@ -979,6 +984,8 @@ gfc_match_iterator (gfc_iterator *iter, int init_flag)
       goto cleanup;
     }
 
+  gfc_match_char ('=');
+
   var->symtree->n.sym->attr.implied_index = 1;
 
   m = init_flag ? gfc_match_init_expr (&e1) : gfc_match_expr (&e1);
diff --git a/gcc/fortran/match.h b/gcc/fortran/match.h
index 7a0f847..67e7741 100644
--- a/gcc/fortran/match.h
+++ b/gcc/fortran/match.h
@@ -216,7 +216,7 @@ match gfc_match_init_expr (gfc_expr **);
 
 /* array.c.  */
 match gfc_match_array_spec (gfc_array_spec **, bool, bool);
-match gfc_match_array_ref (gfc_array_ref *, gfc_array_spec *, int);
+match gfc_match_array_ref (gfc_array_ref *, gfc_array_spec *, int, int);
 match gfc_match_array_constructor (gfc_expr **);
 
 /* interface.c.  */
diff --git a/gcc/fortran/primary.c b/gcc/fortran/primary.c
index 113729f..34b6874 100644
--- a/gcc/fortran/primary.c
+++ b/gcc/fortran/primary.c
@@ -1746,7 +1746,25 @@ gfc_match_varspec (gfc_expr *primary, int equiv_flag, bool sub_flag,
   tail = NULL;
 
   gfc_gobble_whitespace ();
+
+  if (gfc_peek_ascii_char () == '[')
+    {
+      if (sym->attr.dimension)
+	{
+	  gfc_error ("Array section designator, e.g. '(:)', is required "
+		     "besides the coarray designator '[...]' at %C");
+	  return MATCH_ERROR;
+	}
+      if (!sym->attr.codimension)
+	{
+	  gfc_error ("Coarray designator at %C but '%s' is not a coarray",
+		     sym->name);
+	  return MATCH_ERROR;
+	}
+    }
+
   if ((equiv_flag && gfc_peek_ascii_char () == '(')
+      || gfc_peek_ascii_char () == '[' || sym->attr.codimension
       || (sym->attr.dimension && !sym->attr.proc_pointer
 	  && !gfc_is_proc_ptr_comp (primary, NULL)
 	  && !(gfc_matching_procptr_assignment
@@ -1761,7 +1779,7 @@ gfc_match_varspec (gfc_expr *primary, int equiv_flag, bool sub_flag,
       tail->type = REF_ARRAY;
 
       m = gfc_match_array_ref (&tail->u.ar, equiv_flag ? NULL : sym->as,
-			       equiv_flag);
+			       equiv_flag, sym->as ? sym->as->corank : 0);
       if (m != MATCH_YES)
 	return m;
 
@@ -1771,7 +1789,7 @@ gfc_match_varspec (gfc_expr *primary, int equiv_flag, bool sub_flag,
 	  tail = extend_ref (primary, tail);
 	  tail->type = REF_ARRAY;
 
-	  m = gfc_match_array_ref (&tail->u.ar, NULL, equiv_flag);
+	  m = gfc_match_array_ref (&tail->u.ar, NULL, equiv_flag, 0);
 	  if (m != MATCH_YES)
 	    return m;
 	}
@@ -1881,7 +1899,8 @@ gfc_match_varspec (gfc_expr *primary, int equiv_flag, bool sub_flag,
 	  tail = extend_ref (primary, tail);
 	  tail->type = REF_ARRAY;
 
-	  m = gfc_match_array_ref (&tail->u.ar, component->as, equiv_flag);
+	  m = gfc_match_array_ref (&tail->u.ar, component->as, equiv_flag,
+			  component->as->corank);
 	  if (m != MATCH_YES)
 	    return m;
 	}
@@ -1894,7 +1913,8 @@ gfc_match_varspec (gfc_expr *primary, int equiv_flag, bool sub_flag,
 
 	  m = gfc_match_array_ref (&tail->u.ar,
 				   component->ts.u.derived->components->as,
-				   equiv_flag);
+				   equiv_flag,
+			   component->ts.u.derived->components->as->corank);
 	  if (m != MATCH_YES)
 	    return m;
 	}
@@ -1949,6 +1969,13 @@ check_substring:
 	}
     }
 
+  /* F2008, C727.  */
+  if (primary->expr_type == EXPR_PPC && gfc_is_coindexed (primary))
+    {
+      gfc_error ("Coindexed procedure-pointer component at %C");
+      return MATCH_ERROR;
+    }
+
   return MATCH_YES;
 }
 
@@ -2023,7 +2050,9 @@ gfc_variable_attr (gfc_expr *expr, gfc_typespec *ts)
 	    break;
 
 	  case AR_ELEMENT:
-	    allocatable = pointer = 0;
+	    /* Handle coarrays.  */
+	    if (ref->u.ar.dimen > 0)
+	      allocatable = pointer = 0;
 	    break;
 
 	  case AR_UNKNOWN:
@@ -2349,6 +2378,15 @@ gfc_match_structure_constructor (gfc_symbol *sym, gfc_expr **result,
 	  if (m == MATCH_ERROR)
 	    goto cleanup;
 
+	  /* F2008, R457/C725, for PURE C1283.  */
+          if (this_comp->attr.pointer && gfc_is_coindexed (comp_tail->val))
+	    {
+	      gfc_error ("Coindexed expression to pointer component '%s' in "
+			 "structure constructor at %C!", comp_tail->name);
+	      goto cleanup;
+ 	    }
+
+
 	  /* If not explicitly a parent constructor, gather up the components
 	     and build one.  */
 	  if (comp && comp == sym->components
diff --git a/gcc/fortran/resolve.c b/gcc/fortran/resolve.c
index 3ec454e..5e9b25c 100644
--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -77,6 +77,9 @@ static int current_entry_id;
 /* We use bitmaps to determine if a branch target is valid.  */
 static bitmap_obstack labels_obstack;
 
+/* True when simplifying a EXPR_VARIABLE argument to an inquiry function.  */
+static bool inquiry_argument = false;
+
 int
 gfc_is_formal_arg (void)
 {
@@ -932,12 +935,13 @@ resolve_structure_cons (gfc_expr *expr)
 
       /* F2003, C1272 (3).  */
       if (gfc_pure (NULL) && cons->expr->expr_type == EXPR_VARIABLE
-	  && gfc_impure_variable (cons->expr->symtree->n.sym))
+	  && (gfc_impure_variable (cons->expr->symtree->n.sym)
+	      || gfc_is_coindexed (cons->expr)))
 	{
 	  t = FAILURE;
-	  gfc_error ("Invalid expression in the derived type constructor for pointer "
-		     "component '%s' at %L in PURE procedure", comp->name,
-		     &cons->expr->where);
+	  gfc_error ("Invalid expression in the derived type constructor for "
+		     "pointer component '%s' at %L in PURE procedure",
+		     comp->name, &cons->expr->where);
 	}
     }
 
@@ -1319,7 +1323,7 @@ resolve_actual_arglist (gfc_actual_arglist *arg, procedure_type ptype,
   gfc_expr *e;
   int save_need_full_assumed_size;
   gfc_component *comp;
-	
+
   for (; arg; arg = arg->next)
     {
       e = arg->expr;
@@ -1549,6 +1553,15 @@ resolve_actual_arglist (gfc_actual_arglist *arg, procedure_type ptype,
 		}
 	    }
 	}
+
+      /* Fortran 2008, C1237.  */
+      if (e->expr_type == EXPR_VARIABLE && gfc_is_coindexed (e)
+          && gfc_has_ultimate_pointer (e))
+        {
+          gfc_error ("Coindexed actual argument at %L with ultimate pointer "
+		     "component", &e->where);
+          return FAILURE;
+        }
     }
 
   return SUCCESS;
@@ -2590,11 +2603,19 @@ resolve_function (gfc_expr *expr)
   if (expr->symtree && expr->symtree->n.sym)
     p = expr->symtree->n.sym->attr.proc;
 
+  if (expr->value.function.isym && expr->value.function.isym->inquiry)
+    inquiry_argument = true;
   no_formal_args = sym && is_external_proc (sym) && sym->formal == NULL;
+
   if (resolve_actual_arglist (expr->value.function.actual,
 			      p, no_formal_args) == FAILURE)
+    {
+      inquiry_argument = false;
       return FAILURE;
+    }
 
+  inquiry_argument = false;
+ 
   /* Need to setup the call to the correct c_associated, depending on
      the number of cptrs to user gives to compare.  */
   if (sym && sym->attr.is_iso_c == 1)
@@ -3755,6 +3776,17 @@ check_dimension (int i, gfc_array_ref *ar, gfc_array_spec *as)
 {
   mpz_t last_value;
 
+  if (ar->dimen_type[i] == DIMEN_STAR)
+    {
+      gcc_assert (ar->stride[i] == NULL);
+      /* This implies [*] as [*:] and [*:3] are not possible.  */
+      if (ar->start[i] == NULL)
+	{
+	  gcc_assert (ar->end[i] == NULL);
+	  return SUCCESS;
+	}
+    }
+
 /* Given start, end and stride values, calculate the minimum and
    maximum referenced indexes.  */
 
@@ -3763,21 +3795,36 @@ check_dimension (int i, gfc_array_ref *ar, gfc_array_spec *as)
     case DIMEN_VECTOR:
       break;
 
+    case DIMEN_STAR:
     case DIMEN_ELEMENT:
       if (compare_bound (ar->start[i], as->lower[i]) == CMP_LT)
 	{
-	  gfc_warning ("Array reference at %L is out of bounds "
-		       "(%ld < %ld) in dimension %d", &ar->c_where[i],
-		       mpz_get_si (ar->start[i]->value.integer),
-		       mpz_get_si (as->lower[i]->value.integer), i+1);
+	  if (i < as->rank)
+	    gfc_warning ("Array reference at %L is out of bounds "
+			 "(%ld < %ld) in dimension %d", &ar->c_where[i],
+			 mpz_get_si (ar->start[i]->value.integer),
+			 mpz_get_si (as->lower[i]->value.integer), i+1);
+	  else
+	    gfc_warning ("Array reference at %L is out of bounds "
+			 "(%ld < %ld) in codimension %d", &ar->c_where[i],
+			 mpz_get_si (ar->start[i]->value.integer),
+			 mpz_get_si (as->lower[i]->value.integer),
+			 i + 1 - as->rank);
 	  return SUCCESS;
 	}
       if (compare_bound (ar->start[i], as->upper[i]) == CMP_GT)
 	{
-	  gfc_warning ("Array reference at %L is out of bounds "
-		       "(%ld > %ld) in dimension %d", &ar->c_where[i],
-		       mpz_get_si (ar->start[i]->value.integer),
-		       mpz_get_si (as->upper[i]->value.integer), i+1);
+	  if (i < as->rank)
+	    gfc_warning ("Array reference at %L is out of bounds "
+			 "(%ld > %ld) in dimension %d", &ar->c_where[i],
+			 mpz_get_si (ar->start[i]->value.integer),
+			 mpz_get_si (as->upper[i]->value.integer), i+1);
+	  else
+	    gfc_warning ("Array reference at %L is out of bounds "
+			 "(%ld > %ld) in codimension %d", &ar->c_where[i],
+			 mpz_get_si (ar->start[i]->value.integer),
+			 mpz_get_si (as->upper[i]->value.integer),
+			 i + 1 - as->rank);
 	  return SUCCESS;
 	}
 
@@ -3897,10 +3944,32 @@ compare_spec_to_ref (gfc_array_ref *ar)
       return FAILURE;
     }
 
+  /* ar->codimen == 0 is a local array.  */
+  if (as->corank != ar->codimen && ar->codimen != 0)
+    {
+      gfc_error ("Coindex rank mismatch in array reference at %L (%d/%d)",
+		 &ar->where, ar->codimen, as->corank);
+      return FAILURE;
+    }
+
   for (i = 0; i < as->rank; i++)
     if (check_dimension (i, ar, as) == FAILURE)
       return FAILURE;
 
+  /* Local access has no coarray spec.  */
+  if (ar->codimen != 0)
+    for (i = as->rank; i < as->rank + as->corank; i++)
+      {
+	if (ar->dimen_type[i] != DIMEN_ELEMENT && !ar->in_allocate)
+	  {
+	    gfc_error ("Coindex of codimension %d must be a scalar at %L",
+		       i + 1 - as->rank, &ar->where);
+	    return FAILURE;
+	  }
+	if (check_dimension (i, ar, as) == FAILURE)
+	  return FAILURE;
+      }
+
   return SUCCESS;
 }
 
@@ -4069,7 +4138,7 @@ resolve_array_ref (gfc_array_ref *ar)
   int i, check_scalar;
   gfc_expr *e;
 
-  for (i = 0; i < ar->dimen; i++)
+  for (i = 0; i < ar->dimen + ar->codimen; i++)
     {
       check_scalar = ar->dimen_type[i] == DIMEN_RANGE;
 
@@ -4103,6 +4172,9 @@ resolve_array_ref (gfc_array_ref *ar)
 	  }
     }
 
+  if (ar->type == AR_FULL && ar->as->rank == 0)
+    ar->type = AR_ELEMENT;
+
   /* If the reference type is unknown, figure out what kind it is.  */
 
   if (ar->type == AR_UNKNOWN)
@@ -4307,6 +4379,13 @@ resolve_ref (gfc_expr *expr)
 	  switch (ref->u.ar.type)
 	    {
 	    case AR_FULL:
+	      /* Coarray scalar.  */
+	      if (ref->u.ar.as->rank == 0)
+		{
+		  current_part_dimension = 0;
+		  break;
+		}
+	      /* Fall through.  */
 	    case AR_SECTION:
 	      current_part_dimension = 1;
 	      break;
@@ -4576,6 +4655,47 @@ resolve_procedure:
   if (t == SUCCESS && resolve_procedure_expression (e) == FAILURE)
     t = FAILURE;
 
+  /* F2008, C617 and C1229.  */
+  if (!inquiry_argument && (e->ts.type == BT_CLASS || e->ts.type == BT_DERIVED)
+      && gfc_is_coindexed (e))
+    {
+      gfc_ref *ref, *ref2 = NULL;
+
+      if (e->ts.type == BT_CLASS)
+	{
+	  gfc_error ("Polymorphic subobject of coindexed object at %L",
+		     &e->where);
+	  t = FAILURE;
+	}
+
+      for (ref = e->ref; ref; ref = ref->next)
+	{
+	  if (ref->type == REF_COMPONENT)
+	    ref2 = ref;
+	  if (ref->type == REF_ARRAY && ref->u.ar.codimen > 0)
+	    break;
+	}
+
+      for ( ; ref; ref = ref->next)
+	if (ref->type == REF_COMPONENT)
+	  break;
+
+      /* Expression itself is coindexed object.  */
+      if (ref == NULL)
+	{
+	  gfc_component *c;
+	  c = ref2 ? ref2->u.c.component : e->symtree->n.sym->components;
+	  for ( ; c; c = c->next)
+	    if (c->attr.allocatable && c->ts.type == BT_CLASS)
+	      {
+		gfc_error ("Coindexed object with polymorphic allocatable "
+			 "subcomponent at %L", &e->where);
+		t = FAILURE;
+		break;
+	      }
+	}
+    }
+
   return t;
 }
 
@@ -5163,7 +5283,7 @@ resolve_compcall (gfc_expr* e, bool fcn, bool class_members)
    of f03 OOP.  As soon as vtables are in place and contain pointers
    to methods, this will no longer be necessary.  */
 static gfc_expr *list_e;
-static void check_class_members (gfc_symbol *);
+static gfc_try check_class_members (gfc_symbol *);
 static gfc_try class_try;
 static bool fcn_flag;
 
@@ -5172,11 +5292,11 @@ static void
 check_members (gfc_symbol *derived)
 {
   if (derived->attr.flavor == FL_DERIVED)
-    check_class_members (derived);
+    (void) check_class_members (derived);
 }
 
 
-static void 
+static gfc_try 
 check_class_members (gfc_symbol *derived)
 {
   gfc_expr *e;
@@ -5193,7 +5313,7 @@ check_class_members (gfc_symbol *derived)
     {
       gfc_error ("no typebound available procedure named '%s' at %L",
 		 e->value.compcall.name, &e->where);
-      return;
+      return FAILURE;
     }
 
   /* If we have to match a passed class member, force the actual
@@ -5203,6 +5323,9 @@ check_class_members (gfc_symbol *derived)
       if (e->value.compcall.base_object == NULL)
 	e->value.compcall.base_object = extract_compcall_passed_object (e);
 
+      if (e->value.compcall.base_object == NULL)
+	return FAILURE;
+
       if (!derived->attr.abstract)
 	{
 	  e->value.compcall.base_object->ts.type = BT_DERIVED;
@@ -5240,6 +5363,8 @@ check_class_members (gfc_symbol *derived)
   /* Burrow down into grandchildren types.  */
   if (derived->f2k_derived)
     gfc_traverse_ns (derived->f2k_derived, check_members);
+
+  return SUCCESS;
 }
 
 
@@ -5393,7 +5518,9 @@ resolve_typebound_function (gfc_expr* e)
   class_try = SUCCESS;
   fcn_flag = true;
   list_e = gfc_copy_expr (e);
-  check_class_members (derived);
+
+  if (check_class_members (derived) == FAILURE)
+    return FAILURE;
 
   class_try = (resolve_compcall (e, true, false) == SUCCESS)
 		 ? class_try : FAILURE;
@@ -5453,7 +5580,9 @@ resolve_typebound_subroutine (gfc_code *code)
   class_try = SUCCESS;
   fcn_flag = false;
   list_e = gfc_copy_expr (code->expr1);
-  check_class_members (derived);
+
+  if (check_class_members (derived) == FAILURE)
+    return FAILURE;
 
   class_try = (resolve_typebound_call (code) == SUCCESS)
 		 ? class_try : FAILURE;
@@ -5585,10 +5714,16 @@ gfc_try
 gfc_resolve_expr (gfc_expr *e)
 {
   gfc_try t;
+  bool inquiry_save;
 
   if (e == NULL)
     return SUCCESS;
 
+  /* inquiry_argument only applies to variables.  */
+  inquiry_save = inquiry_argument;
+  if (e->expr_type != EXPR_VARIABLE)
+    inquiry_argument = false;
+
   switch (e->expr_type)
     {
     case EXPR_OP:
@@ -5676,6 +5811,8 @@ gfc_resolve_expr (gfc_expr *e)
   if (e->ts.type == BT_CHARACTER && t == SUCCESS && !e->ts.u.cl)
     fixup_charlen (e);
 
+  inquiry_argument = inquiry_save;
+
   return t;
 }
 
@@ -6123,6 +6260,7 @@ static gfc_try
 resolve_allocate_expr (gfc_expr *e, gfc_code *code)
 {
   int i, pointer, allocatable, dimension, check_intent_in, is_abstract;
+  int codimension;
   symbol_attribute attr;
   gfc_ref *ref, *ref2;
   gfc_array_ref *ar;
@@ -6134,8 +6272,17 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code)
   /* Check INTENT(IN), unless the object is a sub-component of a pointer.  */
   check_intent_in = 1;
 
+  /* Mark the ultimost array component as being in allocate to allow DIMEN_STAR
+     checking of coarrays.  */
+  for (ref = e->ref; ref; ref = ref->next)
+    if (ref->next == NULL)
+      break;
+
+  if (ref && ref->type == REF_ARRAY)
+    ref->u.ar.in_allocate = true;
+
   if (gfc_resolve_expr (e) == FAILURE)
-    return FAILURE;
+    goto failure;
 
   /* Make sure the expression is allocatable or a pointer.  If it is
      pointer, the next-to-last reference must be a pointer.  */
@@ -6153,6 +6300,7 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code)
       attr = gfc_expr_attr (e);
       pointer = attr.pointer;
       dimension = attr.dimension;
+      codimension = attr.codimension;
     }
   else
     {
@@ -6161,6 +6309,7 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code)
 	  allocatable = sym->ts.u.derived->components->attr.allocatable;
 	  pointer = sym->ts.u.derived->components->attr.pointer;
 	  dimension = sym->ts.u.derived->components->attr.dimension;
+	  codimension = sym->ts.u.derived->components->attr.codimension;
 	  is_abstract = sym->ts.u.derived->components->attr.abstract;
 	}
       else
@@ -6168,6 +6317,7 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code)
 	  allocatable = sym->attr.allocatable;
 	  pointer = sym->attr.pointer;
 	  dimension = sym->attr.dimension;
+	  codimension = sym->attr.codimension;
 	}
 
       for (ref = e->ref; ref; ref2 = ref, ref = ref->next)
@@ -6183,12 +6333,21 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code)
 		break;
 
 	      case REF_COMPONENT:
+		/* F2008, C644.  */
+		if (gfc_is_coindexed (e))
+		  {
+		    gfc_error ("Coindexed allocatable object at %L",
+			       &e->where);
+		    goto failure;
+		  }
+
 		c = ref->u.c.component;
 		if (c->ts.type == BT_CLASS)
 		  {
 		    allocatable = c->ts.u.derived->components->attr.allocatable;
 		    pointer = c->ts.u.derived->components->attr.pointer;
 		    dimension = c->ts.u.derived->components->attr.dimension;
+		    codimension = c->ts.u.derived->components->attr.codimension;
 		    is_abstract = c->ts.u.derived->components->attr.abstract;
 		  }
 		else
@@ -6196,6 +6355,7 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code)
 		    allocatable = c->attr.allocatable;
 		    pointer = c->attr.pointer;
 		    dimension = c->attr.dimension;
+		    codimension = c->attr.codimension;
 		    is_abstract = c->attr.abstract;
 		  }
 		break;
@@ -6212,7 +6372,7 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code)
     {
       gfc_error ("Allocate-object at %L must be ALLOCATABLE or a POINTER",
 		 &e->where);
-      return FAILURE;
+      goto failure;
     }
 
   /* Some checks for the SOURCE tag.  */
@@ -6223,13 +6383,13 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code)
 	{
 	  gfc_error ("Type of entity at %L is type incompatible with "
 		      "source-expr at %L", &e->where, &code->expr3->where);
-	  return FAILURE;
+	  goto failure;
 	}
 
       /* Check F03:C632 and restriction following Note 6.18.  */
       if (code->expr3->rank > 0
 	  && conformable_arrays (code->expr3, e) == FAILURE)
-	return FAILURE;
+	goto failure;
 
       /* Check F03:C633.  */
       if (code->expr3->ts.kind != e->ts.kind)
@@ -6237,7 +6397,7 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code)
 	  gfc_error ("The allocate-object at %L and the source-expr at %L "
 		      "shall have the same kind type parameter",
 		      &e->where, &code->expr3->where);
-	  return FAILURE;
+	  goto failure;
 	}
     }
   else if (is_abstract&& code->ext.alloc.ts.type == BT_UNKNOWN)
@@ -6245,14 +6405,14 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code)
       gcc_assert (e->ts.type == BT_CLASS);
       gfc_error ("Allocating %s of ABSTRACT base type at %L requires a "
 		 "type-spec or SOURCE=", sym->name, &e->where);
-      return FAILURE;
+      goto failure;
     }
 
   if (check_intent_in && sym->attr.intent == INTENT_IN)
     {
       gfc_error ("Cannot allocate INTENT(IN) variable '%s' at %L",
 		 sym->name, &e->where);
-      return FAILURE;
+      goto failure;
     }
     
   if (!code->expr3)
@@ -6285,16 +6445,17 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code)
 	}
     }
 
-  if (pointer || dimension == 0)
-    return SUCCESS;
+  if (pointer || (dimension == 0 && codimension == 0))
+    goto success;
 
   /* Make sure the next-to-last reference node is an array specification.  */
 
-  if (ref2 == NULL || ref2->type != REF_ARRAY || ref2->u.ar.type == AR_FULL)
+  if (ref2 == NULL || ref2->type != REF_ARRAY || ref2->u.ar.type == AR_FULL
+      || (dimension && ref2->u.ar.dimen == 0))
     {
       gfc_error ("Array specification required in ALLOCATE statement "
 		 "at %L", &e->where);
-      return FAILURE;
+      goto failure;
     }
 
   /* Make sure that the array section reference makes sense in the
@@ -6302,6 +6463,13 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code)
 
   ar = &ref2->u.ar;
 
+  if (codimension && ar->codimen == 0)
+    {
+      gfc_error ("Coarray specification required in ALLOCATE statement "
+		 "at %L", &e->where);
+      goto failure;
+    }
+
   for (i = 0; i < ar->dimen; i++)
     {
       if (ref2->u.ar.type == AR_ELEMENT)
@@ -6322,13 +6490,13 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code)
 
 	case DIMEN_UNKNOWN:
 	case DIMEN_VECTOR:
+	case DIMEN_STAR:
 	  gfc_error ("Bad array specification in ALLOCATE statement at %L",
 		     &e->where);
-	  return FAILURE;
+	  goto failure;
 	}
 
 check_symbols:
-
       for (a = code->ext.alloc.list; a; a = a->next)
 	{
 	  sym = a->expr->symtree->n.sym;
@@ -6345,12 +6513,46 @@ check_symbols:
 	      gfc_error ("'%s' must not appear in the array specification at "
 			 "%L in the same ALLOCATE statement where it is "
 			 "itself allocated", sym->name, &ar->where);
-	      return FAILURE;
+	      goto failure;
 	    }
 	}
     }
 
+  for (i = ar->dimen; i < ar->codimen + ar->dimen; i++)
+    {
+      if (ar->dimen_type[i] == DIMEN_ELEMENT
+	  || ar->dimen_type[i] == DIMEN_RANGE)
+	{
+	  if (i == (ar->dimen + ar->codimen - 1))
+	    {
+	      gfc_error ("Expected '*' in coindex specification in ALLOCATE "
+			 "statement at %L", &e->where);
+	      goto failure;
+	    }
+	  break;
+	}
+
+      if (ar->dimen_type[i] == DIMEN_STAR && i == (ar->dimen + ar->codimen - 1)
+	  && ar->stride[i] == NULL)
+	break;
+
+      gfc_error ("Bad coarray specification in ALLOCATE statement at %L",
+		 &e->where);
+      goto failure;
+    }
+
+  if (codimension)
+    {
+      gfc_error ("Sorry, allocatable coarrays are no yet supported coarray "
+		 "at %L", &e->where);
+      goto failure;
+    }
+
+success:
   return SUCCESS;
+
+failure:
+  return FAILURE;
 }
 
 static void
@@ -8031,17 +8233,35 @@ resolve_ordinary_assign (gfc_code *code, gfc_namespace *ns)
 	    && lhs->expr_type == EXPR_VARIABLE
 	    && lhs->ts.u.derived->attr.pointer_comp
 	    && rhs->expr_type == EXPR_VARIABLE
-	    && gfc_impure_variable (rhs->symtree->n.sym))
+	    && (gfc_impure_variable (rhs->symtree->n.sym)
+		|| gfc_is_coindexed (rhs)))
+	{
+	  /* F2008, C1283.  */
+	  if (gfc_is_coindexed (rhs))
+	    gfc_error ("Coindexed expression at %L is assigned to "
+			"a derived type variable with a POINTER "
+			"component in a PURE procedure",
+			&rhs->where);
+	  else
+	    gfc_error ("The impure variable at %L is assigned to "
+			"a derived type variable with a POINTER "
+			"component in a PURE procedure (12.6)",
+			&rhs->where);
+	  return rval;
+	}
+
+      /* Fortran 2008, C1283.  */
+      if (gfc_is_coindexed (lhs))
 	{
-	  gfc_error ("The impure variable at %L is assigned to "
-		     "a derived type variable with a POINTER "
-		     "component in a PURE procedure (12.6)",
-		     &rhs->where);
+	  gfc_error ("Assignment to coindexed variable at %L in a PURE "
+		     "procedure", &rhs->where);
 	  return rval;
 	}
     }
 
   /* F03:7.4.1.2.  */
+  /* FIXME: Valid in Fortran 2008, unless the LHS is both polymorphic
+     and coindexed; cf. F2008, 7.2.1.2 and PR 43366.  */
   if (lhs->ts.type == BT_CLASS)
     {
       gfc_error ("Variable must not be polymorphic in assignment at %L",
@@ -8049,6 +8269,14 @@ resolve_ordinary_assign (gfc_code *code, gfc_namespace *ns)
       return false;
     }
 
+  /* F2008, Section 7.2.1.2.  */
+  if (gfc_is_coindexed (lhs) && gfc_has_ultimate_allocatable (lhs))
+    {
+      gfc_error ("Coindexed variable must not be have an allocatable ultimate "
+		 "component in assignment at %L", &lhs->where);
+      return false;
+    }
+
   gfc_check_assign (lhs, rhs, 1);
   return false;
 }
@@ -10462,8 +10690,8 @@ resolve_fl_derived (gfc_symbol *sym)
   for (c = sym->components; c != NULL; c = c->next)
     {
       /* F2008, C442.  */
-      if (c->attr.codimension
-	  && (!c->attr.allocatable || c->as->type != AS_DEFERRED))
+      if (c->attr.codimension /* FIXME: c->as check due to PR 43412.  */
+	  && (!c->attr.allocatable || (c->as && c->as->type != AS_DEFERRED)))
 	{
 	  gfc_error ("Coarray component '%s' at %L must be allocatable with "
 		     "deferred shape", c->name, &c->loc);
@@ -11351,9 +11579,9 @@ resolve_symbol (gfc_symbol *sym)
     gfc_error ("Variable '%s' at %L is a coarray or has a coarray "
 	       "component and is not ALLOCATABLE, SAVE nor a "
 	       "dummy argument", sym->name, &sym->declared_at);
-  /* F2008, C528.  */
+  /* F2008, C528.  */  /* FIXME: sym->as check due to PR 43412.  */
   else if (sym->attr.codimension && !sym->attr.allocatable
-      && sym->as->cotype == AS_DEFERRED)
+      && sym->as && sym->as->cotype == AS_DEFERRED)
     gfc_error ("Coarray variable '%s' at %L shall not have codimensions with "
 		"deferred shape", sym->name, &sym->declared_at);
   else if (sym->attr.codimension && sym->attr.allocatable
@@ -11548,6 +11776,13 @@ check_data_variable (gfc_data_variable *var, locus *where)
       if (ref->type == REF_COMPONENT && ref->u.c.component->attr.pointer)
 	has_pointer = 1;
 
+      if (ref->type == REF_ARRAY && ref->u.ar.codimen)
+	{
+	  gfc_error ("DATA element '%s' at %L cannot have a coindex",
+		     sym->name, where);
+	  return FAILURE;
+	}
+
       if (has_pointer
 	    && ref->type == REF_ARRAY
 	    && ref->u.ar.type != AR_FULL)
diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
index 75516ce..cbdd8b9 100644
--- a/gcc/fortran/trans-array.c
+++ b/gcc/fortran/trans-array.c
@@ -2531,6 +2531,9 @@ gfc_conv_array_ref (gfc_se * se, gfc_array_ref * ar, gfc_symbol * sym,
   gfc_se indexse;
   gfc_se tmpse;
 
+  if (ar->dimen == 0)
+    return;
+
   /* Handle scalarized references separately.  */
   if (ar->type != AR_ELEMENT)
     {
@@ -3958,7 +3961,8 @@ gfc_array_allocate (gfc_se * se, gfc_expr * expr, tree pstat)
   /* Find the last reference in the chain.  */
   while (ref && ref->next != NULL)
     {
-      gcc_assert (ref->type != REF_ARRAY || ref->u.ar.type == AR_ELEMENT);
+      gcc_assert (ref->type != REF_ARRAY || ref->u.ar.type == AR_ELEMENT
+		  || (ref->u.ar.dimen == 0 && ref->u.ar.codimen > 0));
       prev_ref = ref;
       ref = ref->next;
     }
@@ -3966,6 +3970,18 @@ gfc_array_allocate (gfc_se * se, gfc_expr * expr, tree pstat)
   if (ref == NULL || ref->type != REF_ARRAY)
     return false;
 
+  /* Return if this is a scalar coarray.  */
+  if (!prev_ref && !expr->symtree->n.sym->attr.dimension)
+    {
+      gcc_assert (expr->symtree->n.sym->attr.codimension);
+      return false;
+    }
+  else if (prev_ref && !prev_ref->u.c.component->attr.dimension)
+    {
+      gcc_assert (prev_ref->u.c.component->attr.codimension);
+      return false;
+    }
+
   if (!prev_ref)
     allocatable_array = expr->symtree->n.sym->attr.allocatable;
   else
@@ -6361,6 +6377,13 @@ gfc_walk_variable_expr (gfc_ss * ss, gfc_expr * expr)
 	continue;
 
       ar = &ref->u.ar;
+
+      if (ar->as->rank == 0)
+	{
+	  /* Scalar coarray.  */
+	  continue;
+	}
+
       switch (ar->type)
 	{
 	case AR_ELEMENT:
diff --git a/gcc/fortran/trans-expr.c b/gcc/fortran/trans-expr.c
index 7e95ce1..10716b7 100644
--- a/gcc/fortran/trans-expr.c
+++ b/gcc/fortran/trans-expr.c
@@ -1848,6 +1848,7 @@ gfc_add_interface_mapping (gfc_interface_mapping * mapping,
   new_sym->as = gfc_copy_array_spec (sym->as);
   new_sym->attr.referenced = 1;
   new_sym->attr.dimension = sym->attr.dimension;
+  new_sym->attr.codimension = sym->attr.codimension;
   new_sym->attr.pointer = sym->attr.pointer;
   new_sym->attr.allocatable = sym->attr.allocatable;
   new_sym->attr.flavor = sym->attr.flavor;
@@ -2076,7 +2077,7 @@ gfc_map_intrinsic_function (gfc_expr *expr, gfc_interface_mapping *mapping)
       break;
 
     case GFC_ISYM_SIZE:
-      if (!sym->as)
+      if (!sym->as || sym->as->rank == 0)
 	return false;
 
       if (arg2 && arg2->expr_type == EXPR_CONSTANT)
@@ -2114,7 +2115,7 @@ gfc_map_intrinsic_function (gfc_expr *expr, gfc_interface_mapping *mapping)
 	/* TODO These implementations of lbound and ubound do not limit if
 	   the size < 0, according to F95's 13.14.53 and 13.14.113.  */
 
-      if (!sym->as)
+      if (!sym->as || sym->as->rank == 0)
 	return false;
 
       if (arg2 && arg2->expr_type == EXPR_CONSTANT)