[GCC 4.8] Initial check-in of GCC 4.8.0

Change-Id: I0719d8a6d0f69b367a6ab6f10eb75622dbf12771

1 files changed, 4163 insertions, 0 deletions

diff --git a/gcc-4.8/gcc/fortran/interface.c b/gcc-4.8/gcc/fortran/interface.c
new file mode 100644
index 000000000..fff8c39ad
--- /dev/null
+++ b/gcc-4.8/gcc/fortran/interface.c
@@ -0,0 +1,4163 @@
+/* Deal with interfaces.
+   Copyright (C) 2000-2013 Free Software Foundation, Inc.
+   Contributed by Andy Vaught
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+
+/* Deal with interfaces.  An explicit interface is represented as a
+   singly linked list of formal argument structures attached to the
+   relevant symbols.  For an implicit interface, the arguments don't
+   point to symbols.  Explicit interfaces point to namespaces that
+   contain the symbols within that interface.
+
+   Implicit interfaces are linked together in a singly linked list
+   along the next_if member of symbol nodes.  Since a particular
+   symbol can only have a single explicit interface, the symbol cannot
+   be part of multiple lists and a single next-member suffices.
+
+   This is not the case for general classes, though.  An operator
+   definition is independent of just about all other uses and has it's
+   own head pointer.
+
+   Nameless interfaces:
+     Nameless interfaces create symbols with explicit interfaces within
+     the current namespace.  They are otherwise unlinked.
+
+   Generic interfaces:
+     The generic name points to a linked list of symbols.  Each symbol
+     has an explicit interface.  Each explicit interface has its own
+     namespace containing the arguments.  Module procedures are symbols in
+     which the interface is added later when the module procedure is parsed.
+
+   User operators:
+     User-defined operators are stored in a their own set of symtrees
+     separate from regular symbols.  The symtrees point to gfc_user_op
+     structures which in turn head up a list of relevant interfaces.
+
+   Extended intrinsics and assignment:
+     The head of these interface lists are stored in the containing namespace.
+
+   Implicit interfaces:
+     An implicit interface is represented as a singly linked list of
+     formal argument list structures that don't point to any symbol
+     nodes -- they just contain types.
+
+
+   When a subprogram is defined, the program unit's name points to an
+   interface as usual, but the link to the namespace is NULL and the
+   formal argument list points to symbols within the same namespace as
+   the program unit name.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "gfortran.h"
+#include "match.h"
+#include "arith.h"
+
+/* The current_interface structure holds information about the
+   interface currently being parsed.  This structure is saved and
+   restored during recursive interfaces.  */
+
+gfc_interface_info current_interface;
+
+
+/* Free a singly linked list of gfc_interface structures.  */
+
+void
+gfc_free_interface (gfc_interface *intr)
+{
+  gfc_interface *next;
+
+  for (; intr; intr = next)
+    {
+      next = intr->next;
+      free (intr);
+    }
+}
+
+
+/* Change the operators unary plus and minus into binary plus and
+   minus respectively, leaving the rest unchanged.  */
+
+static gfc_intrinsic_op
+fold_unary_intrinsic (gfc_intrinsic_op op)
+{
+  switch (op)
+    {
+    case INTRINSIC_UPLUS:
+      op = INTRINSIC_PLUS;
+      break;
+    case INTRINSIC_UMINUS:
+      op = INTRINSIC_MINUS;
+      break;
+    default:
+      break;
+    }
+
+  return op;
+}
+
+
+/* Match a generic specification.  Depending on which type of
+   interface is found, the 'name' or 'op' pointers may be set.
+   This subroutine doesn't return MATCH_NO.  */
+
+match
+gfc_match_generic_spec (interface_type *type,
+			char *name,
+			gfc_intrinsic_op *op)
+{
+  char buffer[GFC_MAX_SYMBOL_LEN + 1];
+  match m;
+  gfc_intrinsic_op i;
+
+  if (gfc_match (" assignment ( = )") == MATCH_YES)
+    {
+      *type = INTERFACE_INTRINSIC_OP;
+      *op = INTRINSIC_ASSIGN;
+      return MATCH_YES;
+    }
+
+  if (gfc_match (" operator ( %o )", &i) == MATCH_YES)
+    {				/* Operator i/f */
+      *type = INTERFACE_INTRINSIC_OP;
+      *op = fold_unary_intrinsic (i);
+      return MATCH_YES;
+    }
+
+  *op = INTRINSIC_NONE;
+  if (gfc_match (" operator ( ") == MATCH_YES)
+    {
+      m = gfc_match_defined_op_name (buffer, 1);
+      if (m == MATCH_NO)
+	goto syntax;
+      if (m != MATCH_YES)
+	return MATCH_ERROR;
+
+      m = gfc_match_char (')');
+      if (m == MATCH_NO)
+	goto syntax;
+      if (m != MATCH_YES)
+	return MATCH_ERROR;
+
+      strcpy (name, buffer);
+      *type = INTERFACE_USER_OP;
+      return MATCH_YES;
+    }
+
+  if (gfc_match_name (buffer) == MATCH_YES)
+    {
+      strcpy (name, buffer);
+      *type = INTERFACE_GENERIC;
+      return MATCH_YES;
+    }
+
+  *type = INTERFACE_NAMELESS;
+  return MATCH_YES;
+
+syntax:
+  gfc_error ("Syntax error in generic specification at %C");
+  return MATCH_ERROR;
+}
+
+
+/* Match one of the five F95 forms of an interface statement.  The
+   matcher for the abstract interface follows.  */
+
+match
+gfc_match_interface (void)
+{
+  char name[GFC_MAX_SYMBOL_LEN + 1];
+  interface_type type;
+  gfc_symbol *sym;
+  gfc_intrinsic_op op;
+  match m;
+
+  m = gfc_match_space ();
+
+  if (gfc_match_generic_spec (&type, name, &op) == MATCH_ERROR)
+    return MATCH_ERROR;
+
+  /* If we're not looking at the end of the statement now, or if this
+     is not a nameless interface but we did not see a space, punt.  */
+  if (gfc_match_eos () != MATCH_YES
+      || (type != INTERFACE_NAMELESS && m != MATCH_YES))
+    {
+      gfc_error ("Syntax error: Trailing garbage in INTERFACE statement "
+		 "at %C");
+      return MATCH_ERROR;
+    }
+
+  current_interface.type = type;
+
+  switch (type)
+    {
+    case INTERFACE_GENERIC:
+      if (gfc_get_symbol (name, NULL, &sym))
+	return MATCH_ERROR;
+
+      if (!sym->attr.generic
+	  && gfc_add_generic (&sym->attr, sym->name, NULL) == FAILURE)
+	return MATCH_ERROR;
+
+      if (sym->attr.dummy)
+	{
+	  gfc_error ("Dummy procedure '%s' at %C cannot have a "
+		     "generic interface", sym->name);
+	  return MATCH_ERROR;
+	}
+
+      current_interface.sym = gfc_new_block = sym;
+      break;
+
+    case INTERFACE_USER_OP:
+      current_interface.uop = gfc_get_uop (name);
+      break;
+
+    case INTERFACE_INTRINSIC_OP:
+      current_interface.op = op;
+      break;
+
+    case INTERFACE_NAMELESS:
+    case INTERFACE_ABSTRACT:
+      break;
+    }
+
+  return MATCH_YES;
+}
+
+
+
+/* Match a F2003 abstract interface.  */
+
+match
+gfc_match_abstract_interface (void)
+{
+  match m;
+
+  if (gfc_notify_std (GFC_STD_F2003, "ABSTRACT INTERFACE at %C")
+		      == FAILURE)
+    return MATCH_ERROR;
+
+  m = gfc_match_eos ();
+
+  if (m != MATCH_YES)
+    {
+      gfc_error ("Syntax error in ABSTRACT INTERFACE statement at %C");
+      return MATCH_ERROR;
+    }
+
+  current_interface.type = INTERFACE_ABSTRACT;
+
+  return m;
+}
+
+
+/* Match the different sort of generic-specs that can be present after
+   the END INTERFACE itself.  */
+
+match
+gfc_match_end_interface (void)
+{
+  char name[GFC_MAX_SYMBOL_LEN + 1];
+  interface_type type;
+  gfc_intrinsic_op op;
+  match m;
+
+  m = gfc_match_space ();
+
+  if (gfc_match_generic_spec (&type, name, &op) == MATCH_ERROR)
+    return MATCH_ERROR;
+
+  /* If we're not looking at the end of the statement now, or if this
+     is not a nameless interface but we did not see a space, punt.  */
+  if (gfc_match_eos () != MATCH_YES
+      || (type != INTERFACE_NAMELESS && m != MATCH_YES))
+    {
+      gfc_error ("Syntax error: Trailing garbage in END INTERFACE "
+		 "statement at %C");
+      return MATCH_ERROR;
+    }
+
+  m = MATCH_YES;
+
+  switch (current_interface.type)
+    {
+    case INTERFACE_NAMELESS:
+    case INTERFACE_ABSTRACT:
+      if (type != INTERFACE_NAMELESS)
+	{
+	  gfc_error ("Expected a nameless interface at %C");
+	  m = MATCH_ERROR;
+	}
+
+      break;
+
+    case INTERFACE_INTRINSIC_OP:
+      if (type != current_interface.type || op != current_interface.op)
+	{
+
+	  if (current_interface.op == INTRINSIC_ASSIGN)
+	    {
+	      m = MATCH_ERROR;
+	      gfc_error ("Expected 'END INTERFACE ASSIGNMENT (=)' at %C");
+	    }
+	  else
+	    {
+	      const char *s1, *s2;
+	      s1 = gfc_op2string (current_interface.op);
+	      s2 = gfc_op2string (op);
+
+	      /* The following if-statements are used to enforce C1202
+		 from F2003.  */
+	      if ((strcmp(s1, "==") == 0 && strcmp(s2, ".eq.") == 0)
+		  || (strcmp(s1, ".eq.") == 0 && strcmp(s2, "==") == 0))
+		break;
+	      if ((strcmp(s1, "/=") == 0 && strcmp(s2, ".ne.") == 0)
+		  || (strcmp(s1, ".ne.") == 0 && strcmp(s2, "/=") == 0))
+		break;
+	      if ((strcmp(s1, "<=") == 0 && strcmp(s2, ".le.") == 0)
+		  || (strcmp(s1, ".le.") == 0 && strcmp(s2, "<=") == 0))
+		break;
+	      if ((strcmp(s1, "<") == 0 && strcmp(s2, ".lt.") == 0)
+		  || (strcmp(s1, ".lt.") == 0 && strcmp(s2, "<") == 0))
+		break;
+	      if ((strcmp(s1, ">=") == 0 && strcmp(s2, ".ge.") == 0)
+		  || (strcmp(s1, ".ge.") == 0 && strcmp(s2, ">=") == 0))
+		break;
+	      if ((strcmp(s1, ">") == 0 && strcmp(s2, ".gt.") == 0)
+		  || (strcmp(s1, ".gt.") == 0 && strcmp(s2, ">") == 0))
+		break;
+
+	      m = MATCH_ERROR;
+	      gfc_error ("Expecting 'END INTERFACE OPERATOR (%s)' at %C, "
+			 "but got %s", s1, s2);
+	    }
+
+	}
+
+      break;
+
+    case INTERFACE_USER_OP:
+      /* Comparing the symbol node names is OK because only use-associated
+	 symbols can be renamed.  */
+      if (type != current_interface.type
+	  || strcmp (current_interface.uop->name, name) != 0)
+	{
+	  gfc_error ("Expecting 'END INTERFACE OPERATOR (.%s.)' at %C",
+		     current_interface.uop->name);
+	  m = MATCH_ERROR;
+	}
+
+      break;
+
+    case INTERFACE_GENERIC:
+      if (type != current_interface.type
+	  || strcmp (current_interface.sym->name, name) != 0)
+	{
+	  gfc_error ("Expecting 'END INTERFACE %s' at %C",
+		     current_interface.sym->name);
+	  m = MATCH_ERROR;
+	}
+
+      break;
+    }
+
+  return m;
+}
+
+
+/* Compare two derived types using the criteria in 4.4.2 of the standard,
+   recursing through gfc_compare_types for the components.  */
+
+int
+gfc_compare_derived_types (gfc_symbol *derived1, gfc_symbol *derived2)
+{
+  gfc_component *dt1, *dt2;
+
+  if (derived1 == derived2)
+    return 1;
+
+  gcc_assert (derived1 && derived2);
+
+  /* Special case for comparing derived types across namespaces.  If the
+     true names and module names are the same and the module name is
+     nonnull, then they are equal.  */
+  if (strcmp (derived1->name, derived2->name) == 0
+      && derived1->module != NULL && derived2->module != NULL
+      && strcmp (derived1->module, derived2->module) == 0)
+    return 1;
+
+  /* Compare type via the rules of the standard.  Both types must have
+     the SEQUENCE or BIND(C) attribute to be equal.  */
+
+  if (strcmp (derived1->name, derived2->name))
+    return 0;
+
+  if (derived1->component_access == ACCESS_PRIVATE
+      || derived2->component_access == ACCESS_PRIVATE)
+    return 0;
+
+  if (!(derived1->attr.sequence && derived2->attr.sequence)
+      && !(derived1->attr.is_bind_c && derived2->attr.is_bind_c))
+    return 0;
+
+  dt1 = derived1->components;
+  dt2 = derived2->components;
+
+  /* Since subtypes of SEQUENCE types must be SEQUENCE types as well, a
+     simple test can speed things up.  Otherwise, lots of things have to
+     match.  */
+  for (;;)
+    {
+      if (strcmp (dt1->name, dt2->name) != 0)
+	return 0;
+
+      if (dt1->attr.access != dt2->attr.access)
+	return 0;
+
+      if (dt1->attr.pointer != dt2->attr.pointer)
+	return 0;
+
+      if (dt1->attr.dimension != dt2->attr.dimension)
+	return 0;
+
+     if (dt1->attr.allocatable != dt2->attr.allocatable)
+	return 0;
+
+      if (dt1->attr.dimension && gfc_compare_array_spec (dt1->as, dt2->as) == 0)
+	return 0;
+
+      /* Make sure that link lists do not put this function into an
+	 endless recursive loop!  */
+      if (!(dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.u.derived)
+	    && !(dt2->ts.type == BT_DERIVED && derived2 == dt2->ts.u.derived)
+	    && gfc_compare_types (&dt1->ts, &dt2->ts) == 0)
+	return 0;
+
+      else if ((dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.u.derived)
+		&& !(dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.u.derived))
+	return 0;
+
+      else if (!(dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.u.derived)
+		&& (dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.u.derived))
+	return 0;
+
+      dt1 = dt1->next;
+      dt2 = dt2->next;
+
+      if (dt1 == NULL && dt2 == NULL)
+	break;
+      if (dt1 == NULL || dt2 == NULL)
+	return 0;
+    }
+
+  return 1;
+}
+
+
+/* Compare two typespecs, recursively if necessary.  */
+
+int
+gfc_compare_types (gfc_typespec *ts1, gfc_typespec *ts2)
+{
+  /* See if one of the typespecs is a BT_VOID, which is what is being used
+     to allow the funcs like c_f_pointer to accept any pointer type.
+     TODO: Possibly should narrow this to just the one typespec coming in
+     that is for the formal arg, but oh well.  */
+  if (ts1->type == BT_VOID || ts2->type == BT_VOID)
+    return 1;
+
+  if (ts1->type == BT_CLASS
+      && ts1->u.derived->components->ts.u.derived->attr.unlimited_polymorphic)
+    return 1;
+
+  /* F2003: C717  */
+  if (ts2->type == BT_CLASS && ts1->type == BT_DERIVED
+      && ts2->u.derived->components->ts.u.derived->attr.unlimited_polymorphic
+      && (ts1->u.derived->attr.sequence || ts1->u.derived->attr.is_bind_c))
+    return 1;
+
+  if (ts1->type != ts2->type
+      && ((ts1->type != BT_DERIVED && ts1->type != BT_CLASS)
+	  || (ts2->type != BT_DERIVED && ts2->type != BT_CLASS)))
+    return 0;
+  if (ts1->type != BT_DERIVED && ts1->type != BT_CLASS)
+    return (ts1->kind == ts2->kind);
+
+  /* Compare derived types.  */
+  if (gfc_type_compatible (ts1, ts2))
+    return 1;
+
+  return gfc_compare_derived_types (ts1->u.derived ,ts2->u.derived);
+}
+
+
+/* Given two symbols that are formal arguments, compare their ranks
+   and types.  Returns nonzero if they have the same rank and type,
+   zero otherwise.  */
+
+static int
+compare_type_rank (gfc_symbol *s1, gfc_symbol *s2)
+{
+  gfc_array_spec *as1, *as2;
+  int r1, r2;
+
+  as1 = (s1->ts.type == BT_CLASS) ? CLASS_DATA (s1)->as : s1->as;
+  as2 = (s2->ts.type == BT_CLASS) ? CLASS_DATA (s2)->as : s2->as;
+
+  r1 = as1 ? as1->rank : 0;
+  r2 = as2 ? as2->rank : 0;
+
+  if (r1 != r2
+      && (!as1 || as1->type != AS_ASSUMED_RANK)
+      && (!as2 || as2->type != AS_ASSUMED_RANK))
+    return 0;			/* Ranks differ.  */
+
+  return gfc_compare_types (&s1->ts, &s2->ts)
+	 || s1->ts.type == BT_ASSUMED || s2->ts.type == BT_ASSUMED;
+}
+
+
+/* Given two symbols that are formal arguments, compare their types
+   and rank and their formal interfaces if they are both dummy
+   procedures.  Returns nonzero if the same, zero if different.  */
+
+static int
+compare_type_rank_if (gfc_symbol *s1, gfc_symbol *s2)
+{
+  if (s1 == NULL || s2 == NULL)
+    return s1 == s2 ? 1 : 0;
+
+  if (s1 == s2)
+    return 1;
+
+  if (s1->attr.flavor != FL_PROCEDURE && s2->attr.flavor != FL_PROCEDURE)
+    return compare_type_rank (s1, s2);
+
+  if (s1->attr.flavor != FL_PROCEDURE || s2->attr.flavor != FL_PROCEDURE)
+    return 0;
+
+  /* At this point, both symbols are procedures.  It can happen that
+     external procedures are compared, where one is identified by usage
+     to be a function or subroutine but the other is not.  Check TKR
+     nonetheless for these cases.  */
+  if (s1->attr.function == 0 && s1->attr.subroutine == 0)
+    return s1->attr.external == 1 ? compare_type_rank (s1, s2) : 0;
+
+  if (s2->attr.function == 0 && s2->attr.subroutine == 0)
+    return s2->attr.external == 1 ? compare_type_rank (s1, s2) : 0;
+
+  /* Now the type of procedure has been identified.  */
+  if (s1->attr.function != s2->attr.function
+      || s1->attr.subroutine != s2->attr.subroutine)
+    return 0;
+
+  if (s1->attr.function && compare_type_rank (s1, s2) == 0)
+    return 0;
+
+  /* Originally, gfortran recursed here to check the interfaces of passed
+     procedures.  This is explicitly not required by the standard.  */
+  return 1;
+}
+
+
+/* Given a formal argument list and a keyword name, search the list
+   for that keyword.  Returns the correct symbol node if found, NULL
+   if not found.  */
+
+static gfc_symbol *
+find_keyword_arg (const char *name, gfc_formal_arglist *f)
+{
+  for (; f; f = f->next)
+    if (strcmp (f->sym->name, name) == 0)
+      return f->sym;
+
+  return NULL;
+}
+
+
+/******** Interface checking subroutines **********/
+
+
+/* Given an operator interface and the operator, make sure that all
+   interfaces for that operator are legal.  */
+
+bool
+gfc_check_operator_interface (gfc_symbol *sym, gfc_intrinsic_op op,
+			      locus opwhere)
+{
+  gfc_formal_arglist *formal;
+  sym_intent i1, i2;
+  bt t1, t2;
+  int args, r1, r2, k1, k2;
+
+  gcc_assert (sym);
+
+  args = 0;
+  t1 = t2 = BT_UNKNOWN;
+  i1 = i2 = INTENT_UNKNOWN;
+  r1 = r2 = -1;
+  k1 = k2 = -1;
+
+  for (formal = gfc_sym_get_dummy_args (sym); formal; formal = formal->next)
+    {
+      gfc_symbol *fsym = formal->sym;
+      if (fsym == NULL)
+	{
+	  gfc_error ("Alternate return cannot appear in operator "
+		     "interface at %L", &sym->declared_at);
+	  return false;
+	}
+      if (args == 0)
+	{
+	  t1 = fsym->ts.type;
+	  i1 = fsym->attr.intent;
+	  r1 = (fsym->as != NULL) ? fsym->as->rank : 0;
+	  k1 = fsym->ts.kind;
+	}
+      if (args == 1)
+	{
+	  t2 = fsym->ts.type;
+	  i2 = fsym->attr.intent;
+	  r2 = (fsym->as != NULL) ? fsym->as->rank : 0;
+	  k2 = fsym->ts.kind;
+	}
+      args++;
+    }
+
+  /* Only +, - and .not. can be unary operators.
+     .not. cannot be a binary operator.  */
+  if (args == 0 || args > 2 || (args == 1 && op != INTRINSIC_PLUS
+				&& op != INTRINSIC_MINUS
+				&& op != INTRINSIC_NOT)
+      || (args == 2 && op == INTRINSIC_NOT))
+    {
+      if (op == INTRINSIC_ASSIGN)
+	gfc_error ("Assignment operator interface at %L must have "
+		   "two arguments", &sym->declared_at);
+      else
+	gfc_error ("Operator interface at %L has the wrong number of arguments",
+		   &sym->declared_at);
+      return false;
+    }
+
+  /* Check that intrinsics are mapped to functions, except
+     INTRINSIC_ASSIGN which should map to a subroutine.  */
+  if (op == INTRINSIC_ASSIGN)
+    {
+      gfc_formal_arglist *dummy_args;
+
+      if (!sym->attr.subroutine)
+	{
+	  gfc_error ("Assignment operator interface at %L must be "
+		     "a SUBROUTINE", &sym->declared_at);
+	  return false;
+	}
+
+      /* Allowed are (per F2003, 12.3.2.1.2 Defined assignments):
+	 - First argument an array with different rank than second,
+	 - First argument is a scalar and second an array,
+	 - Types and kinds do not conform, or
+	 - First argument is of derived type.  */
+      dummy_args = gfc_sym_get_dummy_args (sym);
+      if (dummy_args->sym->ts.type != BT_DERIVED
+	  && dummy_args->sym->ts.type != BT_CLASS
+	  && (r2 == 0 || r1 == r2)
+	  && (dummy_args->sym->ts.type == dummy_args->next->sym->ts.type
+	      || (gfc_numeric_ts (&dummy_args->sym->ts)
+		  && gfc_numeric_ts (&dummy_args->next->sym->ts))))
+	{
+	  gfc_error ("Assignment operator interface at %L must not redefine "
+		     "an INTRINSIC type assignment", &sym->declared_at);
+	  return false;
+	}
+    }
+  else
+    {
+      if (!sym->attr.function)
+	{
+	  gfc_error ("Intrinsic operator interface at %L must be a FUNCTION",
+		     &sym->declared_at);
+	  return false;
+	}
+    }
+
+  /* Check intents on operator interfaces.  */
+  if (op == INTRINSIC_ASSIGN)
+    {
+      if (i1 != INTENT_OUT && i1 != INTENT_INOUT)
+	{
+	  gfc_error ("First argument of defined assignment at %L must be "
+		     "INTENT(OUT) or INTENT(INOUT)", &sym->declared_at);
+	  return false;
+	}
+
+      if (i2 != INTENT_IN)
+	{
+	  gfc_error ("Second argument of defined assignment at %L must be "
+		     "INTENT(IN)", &sym->declared_at);
+	  return false;
+	}
+    }
+  else
+    {
+      if (i1 != INTENT_IN)
+	{
+	  gfc_error ("First argument of operator interface at %L must be "
+		     "INTENT(IN)", &sym->declared_at);
+	  return false;
+	}
+
+      if (args == 2 && i2 != INTENT_IN)
+	{
+	  gfc_error ("Second argument of operator interface at %L must be "
+		     "INTENT(IN)", &sym->declared_at);
+	  return false;
+	}
+    }
+
+  /* From now on, all we have to do is check that the operator definition
+     doesn't conflict with an intrinsic operator. The rules for this
+     game are defined in 7.1.2 and 7.1.3 of both F95 and F2003 standards,
+     as well as 12.3.2.1.1 of Fortran 2003:
+
+     "If the operator is an intrinsic-operator (R310), the number of
+     function arguments shall be consistent with the intrinsic uses of
+     that operator, and the types, kind type parameters, or ranks of the
+     dummy arguments shall differ from those required for the intrinsic
+     operation (7.1.2)."  */
+
+#define IS_NUMERIC_TYPE(t) \
+  ((t) == BT_INTEGER || (t) == BT_REAL || (t) == BT_COMPLEX)
+
+  /* Unary ops are easy, do them first.  */
+  if (op == INTRINSIC_NOT)
+    {
+      if (t1 == BT_LOGICAL)
+	goto bad_repl;
+      else
+	return true;
+    }
+
+  if (args == 1 && (op == INTRINSIC_PLUS || op == INTRINSIC_MINUS))
+    {
+      if (IS_NUMERIC_TYPE (t1))
+	goto bad_repl;
+      else
+	return true;
+    }
+
+  /* Character intrinsic operators have same character kind, thus
+     operator definitions with operands of different character kinds
+     are always safe.  */
+  if (t1 == BT_CHARACTER && t2 == BT_CHARACTER && k1 != k2)
+    return true;
+
+  /* Intrinsic operators always perform on arguments of same rank,
+     so different ranks is also always safe.  (rank == 0) is an exception
+     to that, because all intrinsic operators are elemental.  */
+  if (r1 != r2 && r1 != 0 && r2 != 0)
+    return true;
+
+  switch (op)
+  {
+    case INTRINSIC_EQ:
+    case INTRINSIC_EQ_OS:
+    case INTRINSIC_NE:
+    case INTRINSIC_NE_OS:
+      if (t1 == BT_CHARACTER && t2 == BT_CHARACTER)
+	goto bad_repl;
+      /* Fall through.  */
+
+    case INTRINSIC_PLUS:
+    case INTRINSIC_MINUS:
+    case INTRINSIC_TIMES:
+    case INTRINSIC_DIVIDE:
+    case INTRINSIC_POWER:
+      if (IS_NUMERIC_TYPE (t1) && IS_NUMERIC_TYPE (t2))
+	goto bad_repl;
+      break;
+
+    case INTRINSIC_GT:
+    case INTRINSIC_GT_OS:
+    case INTRINSIC_GE:
+    case INTRINSIC_GE_OS:
+    case INTRINSIC_LT:
+    case INTRINSIC_LT_OS:
+    case INTRINSIC_LE:
+    case INTRINSIC_LE_OS:
+      if (t1 == BT_CHARACTER && t2 == BT_CHARACTER)
+	goto bad_repl;
+      if ((t1 == BT_INTEGER || t1 == BT_REAL)
+	  && (t2 == BT_INTEGER || t2 == BT_REAL))
+	goto bad_repl;
+      break;
+
+    case INTRINSIC_CONCAT:
+      if (t1 == BT_CHARACTER && t2 == BT_CHARACTER)
+	goto bad_repl;
+      break;
+
+    case INTRINSIC_AND:
+    case INTRINSIC_OR:
+    case INTRINSIC_EQV:
+    case INTRINSIC_NEQV:
+      if (t1 == BT_LOGICAL && t2 == BT_LOGICAL)
+	goto bad_repl;
+      break;
+
+    default:
+      break;
+  }
+
+  return true;
+
+#undef IS_NUMERIC_TYPE
+
+bad_repl:
+  gfc_error ("Operator interface at %L conflicts with intrinsic interface",
+	     &opwhere);
+  return false;
+}
+
+
+/* Given a pair of formal argument lists, we see if the two lists can
+   be distinguished by counting the number of nonoptional arguments of
+   a given type/rank in f1 and seeing if there are less then that
+   number of those arguments in f2 (including optional arguments).
+   Since this test is asymmetric, it has to be called twice to make it
+   symmetric. Returns nonzero if the argument lists are incompatible
+   by this test. This subroutine implements rule 1 of section F03:16.2.3.
+   'p1' and 'p2' are the PASS arguments of both procedures (if applicable).  */
+
+static int
+count_types_test (gfc_formal_arglist *f1, gfc_formal_arglist *f2,
+		  const char *p1, const char *p2)
+{
+  int rc, ac1, ac2, i, j, k, n1;
+  gfc_formal_arglist *f;
+
+  typedef struct
+  {
+    int flag;
+    gfc_symbol *sym;
+  }
+  arginfo;
+
+  arginfo *arg;
+
+  n1 = 0;
+
+  for (f = f1; f; f = f->next)
+    n1++;
+
+  /* Build an array of integers that gives the same integer to
+     arguments of the same type/rank.  */
+  arg = XCNEWVEC (arginfo, n1);
+
+  f = f1;
+  for (i = 0; i < n1; i++, f = f->next)
+    {
+      arg[i].flag = -1;
+      arg[i].sym = f->sym;
+    }
+
+  k = 0;
+
+  for (i = 0; i < n1; i++)
+    {
+      if (arg[i].flag != -1)
+	continue;
+
+      if (arg[i].sym && (arg[i].sym->attr.optional
+			 || (p1 && strcmp (arg[i].sym->name, p1) == 0)))
+	continue;		/* Skip OPTIONAL and PASS arguments.  */
+
+      arg[i].flag = k;
+
+      /* Find other non-optional, non-pass arguments of the same type/rank.  */
+      for (j = i + 1; j < n1; j++)
+	if ((arg[j].sym == NULL
+	     || !(arg[j].sym->attr.optional
+		  || (p1 && strcmp (arg[j].sym->name, p1) == 0)))
+	    && (compare_type_rank_if (arg[i].sym, arg[j].sym)
+	        || compare_type_rank_if (arg[j].sym, arg[i].sym)))
+	  arg[j].flag = k;
+
+      k++;
+    }
+
+  /* Now loop over each distinct type found in f1.  */
+  k = 0;
+  rc = 0;
+
+  for (i = 0; i < n1; i++)
+    {
+      if (arg[i].flag != k)
+	continue;
+
+      ac1 = 1;
+      for (j = i + 1; j < n1; j++)
+	if (arg[j].flag == k)
+	  ac1++;
+
+      /* Count the number of non-pass arguments in f2 with that type,
+	 including those that are optional.  */
+      ac2 = 0;
+
+      for (f = f2; f; f = f->next)
+	if ((!p2 || strcmp (f->sym->name, p2) != 0)
+	    && (compare_type_rank_if (arg[i].sym, f->sym)
+		|| compare_type_rank_if (f->sym, arg[i].sym)))
+	  ac2++;
+
+      if (ac1 > ac2)
+	{
+	  rc = 1;
+	  break;
+	}
+
+      k++;
+    }
+
+  free (arg);
+
+  return rc;
+}
+
+
+/* Perform the correspondence test in rule (3) of F08:C1215.
+   Returns zero if no argument is found that satisfies this rule,
+   nonzero otherwise. 'p1' and 'p2' are the PASS arguments of both procedures
+   (if applicable).
+
+   This test is also not symmetric in f1 and f2 and must be called
+   twice.  This test finds problems caused by sorting the actual
+   argument list with keywords.  For example:
+
+   INTERFACE FOO
+     SUBROUTINE F1(A, B)
+       INTEGER :: A ; REAL :: B
+     END SUBROUTINE F1
+
+     SUBROUTINE F2(B, A)
+       INTEGER :: A ; REAL :: B
+     END SUBROUTINE F1
+   END INTERFACE FOO
+
+   At this point, 'CALL FOO(A=1, B=1.0)' is ambiguous.  */
+
+static int
+generic_correspondence (gfc_formal_arglist *f1, gfc_formal_arglist *f2,
+			const char *p1, const char *p2)
+{
+  gfc_formal_arglist *f2_save, *g;
+  gfc_symbol *sym;
+
+  f2_save = f2;
+
+  while (f1)
+    {
+      if (f1->sym->attr.optional)
+	goto next;
+
+      if (p1 && strcmp (f1->sym->name, p1) == 0)
+	f1 = f1->next;
+      if (f2 && p2 && strcmp (f2->sym->name, p2) == 0)
+	f2 = f2->next;
+
+      if (f2 != NULL && (compare_type_rank (f1->sym, f2->sym)
+			 || compare_type_rank (f2->sym, f1->sym))
+	  && !((gfc_option.allow_std & GFC_STD_F2008)
+	       && ((f1->sym->attr.allocatable && f2->sym->attr.pointer)
+		   || (f2->sym->attr.allocatable && f1->sym->attr.pointer))))
+	goto next;
+
+      /* Now search for a disambiguating keyword argument starting at
+	 the current non-match.  */
+      for (g = f1; g; g = g->next)
+	{
+	  if (g->sym->attr.optional || (p1 && strcmp (g->sym->name, p1) == 0))
+	    continue;
+
+	  sym = find_keyword_arg (g->sym->name, f2_save);
+	  if (sym == NULL || !compare_type_rank (g->sym, sym)
+	      || ((gfc_option.allow_std & GFC_STD_F2008)
+		  && ((sym->attr.allocatable && g->sym->attr.pointer)
+		      || (sym->attr.pointer && g->sym->attr.allocatable))))
+	    return 1;
+	}
+
+    next:
+      if (f1 != NULL)
+	f1 = f1->next;
+      if (f2 != NULL)
+	f2 = f2->next;
+    }
+
+  return 0;
+}
+
+
+/* Check if the characteristics of two dummy arguments match,
+   cf. F08:12.3.2.  */
+
+static gfc_try
+check_dummy_characteristics (gfc_symbol *s1, gfc_symbol *s2,
+			     bool type_must_agree, char *errmsg, int err_len)
+{
+  /* Check type and rank.  */
+  if (type_must_agree && !compare_type_rank (s2, s1))
+    {
+      snprintf (errmsg, err_len, "Type/rank mismatch in argument '%s'",
+		s1->name);
+      return FAILURE;
+    }
+
+  /* Check INTENT.  */
+  if (s1->attr.intent != s2->attr.intent)
+    {
+      snprintf (errmsg, err_len, "INTENT mismatch in argument '%s'",
+		s1->name);
+      return FAILURE;
+    }
+
+  /* Check OPTIONAL attribute.  */
+  if (s1->attr.optional != s2->attr.optional)
+    {
+      snprintf (errmsg, err_len, "OPTIONAL mismatch in argument '%s'",
+		s1->name);
+      return FAILURE;
+    }
+
+  /* Check ALLOCATABLE attribute.  */
+  if (s1->attr.allocatable != s2->attr.allocatable)
+    {
+      snprintf (errmsg, err_len, "ALLOCATABLE mismatch in argument '%s'",
+		s1->name);
+      return FAILURE;
+    }
+
+  /* Check POINTER attribute.  */
+  if (s1->attr.pointer != s2->attr.pointer)
+    {
+      snprintf (errmsg, err_len, "POINTER mismatch in argument '%s'",
+		s1->name);
+      return FAILURE;
+    }
+
+  /* Check TARGET attribute.  */
+  if (s1->attr.target != s2->attr.target)
+    {
+      snprintf (errmsg, err_len, "TARGET mismatch in argument '%s'",
+		s1->name);
+      return FAILURE;
+    }
+
+  /* FIXME: Do more comprehensive testing of attributes, like e.g.
+	    ASYNCHRONOUS, CONTIGUOUS, VALUE, VOLATILE, etc.  */
+
+  /* Check interface of dummy procedures.  */
+  if (s1->attr.flavor == FL_PROCEDURE)
+    {
+      char err[200];
+      if (!gfc_compare_interfaces (s1, s2, s2->name, 0, 1, err, sizeof(err),
+				   NULL, NULL))
+	{
+	  snprintf (errmsg, err_len, "Interface mismatch in dummy procedure "
+		    "'%s': %s", s1->name, err);
+	  return FAILURE;
+	}
+    }
+
+  /* Check string length.  */
+  if (s1->ts.type == BT_CHARACTER
+      && s1->ts.u.cl && s1->ts.u.cl->length
+      && s2->ts.u.cl && s2->ts.u.cl->length)
+    {
+      int compval = gfc_dep_compare_expr (s1->ts.u.cl->length,
+					  s2->ts.u.cl->length);
+      switch (compval)
+      {
+	case -1:
+	case  1:
+	case -3:
+	  snprintf (errmsg, err_len, "Character length mismatch "
+		    "in argument '%s'", s1->name);
+	  return FAILURE;
+
+	case -2:
+	  /* FIXME: Implement a warning for this case.
+	  gfc_warning ("Possible character length mismatch in argument '%s'",
+		       s1->name);*/
+	  break;
+
+	case 0:
+	  break;
+
+	default:
+	  gfc_internal_error ("check_dummy_characteristics: Unexpected result "
+			      "%i of gfc_dep_compare_expr", compval);
+	  break;
+      }
+    }
+
+  /* Check array shape.  */
+  if (s1->as && s2->as)
+    {
+      int i, compval;
+      gfc_expr *shape1, *shape2;
+
+      if (s1->as->type != s2->as->type)
+	{
+	  snprintf (errmsg, err_len, "Shape mismatch in argument '%s'",
+		    s1->name);
+	  return FAILURE;
+	}
+
+      if (s1->as->type == AS_EXPLICIT)
+	for (i = 0; i < s1->as->rank + s1->as->corank; i++)
+	  {
+	    shape1 = gfc_subtract (gfc_copy_expr (s1->as->upper[i]),
+				  gfc_copy_expr (s1->as->lower[i]));
+	    shape2 = gfc_subtract (gfc_copy_expr (s2->as->upper[i]),
+				  gfc_copy_expr (s2->as->lower[i]));
+	    compval = gfc_dep_compare_expr (shape1, shape2);
+	    gfc_free_expr (shape1);
+	    gfc_free_expr (shape2);
+	    switch (compval)
+	    {
+	      case -1:
+	      case  1:
+	      case -3:
+		snprintf (errmsg, err_len, "Shape mismatch in dimension %i of "
+			  "argument '%s'", i + 1, s1->name);
+		return FAILURE;
+
+	      case -2:
+		/* FIXME: Implement a warning for this case.
+		gfc_warning ("Possible shape mismatch in argument '%s'",
+			    s1->name);*/
+		break;
+
+	      case 0:
+		break;
+
+	      default:
+		gfc_internal_error ("check_dummy_characteristics: Unexpected "
+				    "result %i of gfc_dep_compare_expr",
+				    compval);
+		break;
+	    }
+	  }
+    }
+
+  return SUCCESS;
+}
+
+
+/* Check if the characteristics of two function results match,
+   cf. F08:12.3.3.  */
+
+static gfc_try
+check_result_characteristics (gfc_symbol *s1, gfc_symbol *s2,
+			      char *errmsg, int err_len)
+{
+  gfc_symbol *r1, *r2;
+
+  r1 = s1->result ? s1->result : s1;
+  r2 = s2->result ? s2->result : s2;
+
+  if (r1->ts.type == BT_UNKNOWN)
+    return SUCCESS;
+
+  /* Check type and rank.  */
+  if (!compare_type_rank (r1, r2))
+    {
+      snprintf (errmsg, err_len, "Type/rank mismatch in function result");
+      return FAILURE;
+    }
+
+  /* Check ALLOCATABLE attribute.  */
+  if (r1->attr.allocatable != r2->attr.allocatable)
+    {
+      snprintf (errmsg, err_len, "ALLOCATABLE attribute mismatch in "
+		"function result");
+      return FAILURE;
+    }
+
+  /* Check POINTER attribute.  */
+  if (r1->attr.pointer != r2->attr.pointer)
+    {
+      snprintf (errmsg, err_len, "POINTER attribute mismatch in "
+		"function result");
+      return FAILURE;
+    }
+
+  /* Check CONTIGUOUS attribute.  */
+  if (r1->attr.contiguous != r2->attr.contiguous)
+    {
+      snprintf (errmsg, err_len, "CONTIGUOUS attribute mismatch in "
+		"function result");
+      return FAILURE;
+    }
+
+  /* Check PROCEDURE POINTER attribute.  */
+  if (r1 != s1 && r1->attr.proc_pointer != r2->attr.proc_pointer)
+    {
+      snprintf (errmsg, err_len, "PROCEDURE POINTER mismatch in "
+		"function result");
+      return FAILURE;
+    }
+
+  /* Check string length.  */
+  if (r1->ts.type == BT_CHARACTER && r1->ts.u.cl && r2->ts.u.cl)
+    {
+      if (r1->ts.deferred != r2->ts.deferred)
+	{
+	  snprintf (errmsg, err_len, "Character length mismatch "
+		    "in function result");
+	  return FAILURE;
+	}
+
+      if (r1->ts.u.cl->length)
+	{
+	  int compval = gfc_dep_compare_expr (r1->ts.u.cl->length,
+					      r2->ts.u.cl->length);
+	  switch (compval)
+	  {
+	    case -1:
+	    case  1:
+	    case -3:
+	      snprintf (errmsg, err_len, "Character length mismatch "
+			"in function result");
+	      return FAILURE;
+
+	    case -2:
+	      /* FIXME: Implement a warning for this case.
+	      snprintf (errmsg, err_len, "Possible character length mismatch "
+			"in function result");*/
+	      break;
+
+	    case 0:
+	      break;
+
+	    default:
+	      gfc_internal_error ("check_result_characteristics (1): Unexpected "
+				  "result %i of gfc_dep_compare_expr", compval);
+	      break;
+	  }
+	}
+    }
+
+  /* Check array shape.  */
+  if (!r1->attr.allocatable && !r1->attr.pointer && r1->as && r2->as)
+    {
+      int i, compval;
+      gfc_expr *shape1, *shape2;
+
+      if (r1->as->type != r2->as->type)
+	{
+	  snprintf (errmsg, err_len, "Shape mismatch in function result");
+	  return FAILURE;
+	}
+
+      if (r1->as->type == AS_EXPLICIT)
+	for (i = 0; i < r1->as->rank + r1->as->corank; i++)
+	  {
+	    shape1 = gfc_subtract (gfc_copy_expr (r1->as->upper[i]),
+				   gfc_copy_expr (r1->as->lower[i]));
+	    shape2 = gfc_subtract (gfc_copy_expr (r2->as->upper[i]),
+				   gfc_copy_expr (r2->as->lower[i]));
+	    compval = gfc_dep_compare_expr (shape1, shape2);
+	    gfc_free_expr (shape1);
+	    gfc_free_expr (shape2);
+	    switch (compval)
+	    {
+	      case -1:
+	      case  1:
+	      case -3:
+		snprintf (errmsg, err_len, "Shape mismatch in dimension %i of "
+			  "function result", i + 1);
+		return FAILURE;
+
+	      case -2:
+		/* FIXME: Implement a warning for this case.
+		gfc_warning ("Possible shape mismatch in return value");*/
+		break;
+
+	      case 0:
+		break;
+
+	      default:
+		gfc_internal_error ("check_result_characteristics (2): "
+				    "Unexpected result %i of "
+				    "gfc_dep_compare_expr", compval);
+		break;
+	    }
+	  }
+    }
+
+  return SUCCESS;
+}
+
+
+/* 'Compare' two formal interfaces associated with a pair of symbols.
+   We return nonzero if there exists an actual argument list that
+   would be ambiguous between the two interfaces, zero otherwise.
+   'strict_flag' specifies whether all the characteristics are
+   required to match, which is not the case for ambiguity checks.
+   'p1' and 'p2' are the PASS arguments of both procedures (if applicable).  */
+
+int
+gfc_compare_interfaces (gfc_symbol *s1, gfc_symbol *s2, const char *name2,
+			int generic_flag, int strict_flag,
+			char *errmsg, int err_len,
+			const char *p1, const char *p2)
+{
+  gfc_formal_arglist *f1, *f2;
+
+  gcc_assert (name2 != NULL);
+
+  if (s1->attr.function && (s2->attr.subroutine
+      || (!s2->attr.function && s2->ts.type == BT_UNKNOWN
+	  && gfc_get_default_type (name2, s2->ns)->type == BT_UNKNOWN)))
+    {
+      if (errmsg != NULL)
+	snprintf (errmsg, err_len, "'%s' is not a function", name2);
+      return 0;
+    }
+
+  if (s1->attr.subroutine && s2->attr.function)
+    {
+      if (errmsg != NULL)
+	snprintf (errmsg, err_len, "'%s' is not a subroutine", name2);
+      return 0;
+    }
+
+  /* Do strict checks on all characteristics
+     (for dummy procedures and procedure pointer assignments).  */
+  if (!generic_flag && strict_flag)
+    {
+      if (s1->attr.function && s2->attr.function)
+	{
+	  /* If both are functions, check result characteristics.  */
+	  if (check_result_characteristics (s1, s2, errmsg, err_len)
+	      == FAILURE)
+	    return 0;
+	}
+
+      if (s1->attr.pure && !s2->attr.pure)
+	{
+	  snprintf (errmsg, err_len, "Mismatch in PURE attribute");
+	  return 0;
+	}
+      if (s1->attr.elemental && !s2->attr.elemental)
+	{
+	  snprintf (errmsg, err_len, "Mismatch in ELEMENTAL attribute");
+	  return 0;
+	}
+    }
+
+  if (s1->attr.if_source == IFSRC_UNKNOWN
+      || s2->attr.if_source == IFSRC_UNKNOWN)
+    return 1;
+
+  f1 = gfc_sym_get_dummy_args (s1);
+  f2 = gfc_sym_get_dummy_args (s2);
+
+  if (f1 == NULL && f2 == NULL)
+    return 1;			/* Special case: No arguments.  */
+
+  if (generic_flag)
+    {
+      if (count_types_test (f1, f2, p1, p2)
+	  || count_types_test (f2, f1, p2, p1))
+	return 0;
+      if (generic_correspondence (f1, f2, p1, p2)
+	  || generic_correspondence (f2, f1, p2, p1))
+	return 0;
+    }
+  else
+    /* Perform the abbreviated correspondence test for operators (the
+       arguments cannot be optional and are always ordered correctly).
+       This is also done when comparing interfaces for dummy procedures and in
+       procedure pointer assignments.  */
+
+    for (;;)
+      {
+	/* Check existence.  */
+	if (f1 == NULL && f2 == NULL)
+	  break;
+	if (f1 == NULL || f2 == NULL)
+	  {
+	    if (errmsg != NULL)
+	      snprintf (errmsg, err_len, "'%s' has the wrong number of "
+			"arguments", name2);
+	    return 0;
+	  }
+
+	if (UNLIMITED_POLY (f1->sym))
+	  goto next;
+
+	if (strict_flag)
+	  {
+	    /* Check all characteristics.  */
+	    if (check_dummy_characteristics (f1->sym, f2->sym,
+					     true, errmsg, err_len) == FAILURE)
+	      return 0;
+	  }
+	else if (!compare_type_rank (f2->sym, f1->sym))
+	  {
+	    /* Only check type and rank.  */
+	    if (errmsg != NULL)
+	      snprintf (errmsg, err_len, "Type/rank mismatch in argument '%s'",
+			f1->sym->name);
+	    return 0;
+	  }
+next:
+	f1 = f1->next;
+	f2 = f2->next;
+      }
+
+  return 1;
+}
+
+
+/* Given a pointer to an interface pointer, remove duplicate
+   interfaces and make sure that all symbols are either functions
+   or subroutines, and all of the same kind.  Returns nonzero if
+   something goes wrong.  */
+
+static int
+check_interface0 (gfc_interface *p, const char *interface_name)
+{
+  gfc_interface *psave, *q, *qlast;
+
+  psave = p;
+  for (; p; p = p->next)
+    {
+      /* Make sure all symbols in the interface have been defined as
+	 functions or subroutines.  */
+      if (((!p->sym->attr.function && !p->sym->attr.subroutine)
+	   || !p->sym->attr.if_source)
+	  && p->sym->attr.flavor != FL_DERIVED)
+	{
+	  if (p->sym->attr.external)
+	    gfc_error ("Procedure '%s' in %s at %L has no explicit interface",
+		       p->sym->name, interface_name, &p->sym->declared_at);
+	  else
+	    gfc_error ("Procedure '%s' in %s at %L is neither function nor "
+		       "subroutine", p->sym->name, interface_name,
+		      &p->sym->declared_at);
+	  return 1;
+	}
+
+      /* Verify that procedures are either all SUBROUTINEs or all FUNCTIONs.  */
+      if ((psave->sym->attr.function && !p->sym->attr.function
+	   && p->sym->attr.flavor != FL_DERIVED)
+	  || (psave->sym->attr.subroutine && !p->sym->attr.subroutine))
+	{
+	  if (p->sym->attr.flavor != FL_DERIVED)
+	    gfc_error ("In %s at %L procedures must be either all SUBROUTINEs"
+		       " or all FUNCTIONs", interface_name,
+		       &p->sym->declared_at);
+	  else
+	    gfc_error ("In %s at %L procedures must be all FUNCTIONs as the "
+		       "generic name is also the name of a derived type",
+		       interface_name, &p->sym->declared_at);
+	  return 1;
+	}
+
+      /* F2003, C1207. F2008, C1207.  */
+      if (p->sym->attr.proc == PROC_INTERNAL
+	  && gfc_notify_std (GFC_STD_F2008, "Internal procedure "
+			     "'%s' in %s at %L", p->sym->name, interface_name,
+			     &p->sym->declared_at) == FAILURE)
+	return 1;
+    }
+  p = psave;
+
+  /* Remove duplicate interfaces in this interface list.  */
+  for (; p; p = p->next)
+    {
+      qlast = p;
+
+      for (q = p->next; q;)
+	{
+	  if (p->sym != q->sym)
+	    {
+	      qlast = q;
+	      q = q->next;
+	    }
+	  else
+	    {
+	      /* Duplicate interface.  */
+	      qlast->next = q->next;
+	      free (q);
+	      q = qlast->next;
+	    }
+	}
+    }
+
+  return 0;
+}
+
+
+/* Check lists of interfaces to make sure that no two interfaces are
+   ambiguous.  Duplicate interfaces (from the same symbol) are OK here.  */
+
+static int
+check_interface1 (gfc_interface *p, gfc_interface *q0,
+		  int generic_flag, const char *interface_name,
+		  bool referenced)
+{
+  gfc_interface *q;
+  for (; p; p = p->next)
+    for (q = q0; q; q = q->next)
+      {
+	if (p->sym == q->sym)
+	  continue;		/* Duplicates OK here.  */
+
+	if (p->sym->name == q->sym->name && p->sym->module == q->sym->module)
+	  continue;
+
+	if (p->sym->attr.flavor != FL_DERIVED
+	    && q->sym->attr.flavor != FL_DERIVED
+	    && gfc_compare_interfaces (p->sym, q->sym, q->sym->name,
+				       generic_flag, 0, NULL, 0, NULL, NULL))
+	  {
+	    if (referenced)
+	      gfc_error ("Ambiguous interfaces '%s' and '%s' in %s at %L",
+			 p->sym->name, q->sym->name, interface_name,
+			 &p->where);
+	    else if (!p->sym->attr.use_assoc && q->sym->attr.use_assoc)
+	      gfc_warning ("Ambiguous interfaces '%s' and '%s' in %s at %L",
+			   p->sym->name, q->sym->name, interface_name,
+			   &p->where);
+	    else
+	      gfc_warning ("Although not referenced, '%s' has ambiguous "
+			   "interfaces at %L", interface_name, &p->where);
+	    return 1;
+	  }
+      }
+  return 0;
+}
+
+
+/* Check the generic and operator interfaces of symbols to make sure
+   that none of the interfaces conflict.  The check has to be done
+   after all of the symbols are actually loaded.  */
+
+static void
+check_sym_interfaces (gfc_symbol *sym)
+{
+  char interface_name[100];
+  gfc_interface *p;
+
+  if (sym->ns != gfc_current_ns)
+    return;
+
+  if (sym->generic != NULL)
+    {
+      sprintf (interface_name, "generic interface '%s'", sym->name);
+      if (check_interface0 (sym->generic, interface_name))
+	return;
+
+      for (p = sym->generic; p; p = p->next)
+	{
+	  if (p->sym->attr.mod_proc
+	      && (p->sym->attr.if_source != IFSRC_DECL
+		  || p->sym->attr.procedure))
+	    {
+	      gfc_error ("'%s' at %L is not a module procedure",
+			 p->sym->name, &p->where);
+	      return;
+	    }
+	}
+
+      /* Originally, this test was applied to host interfaces too;
+	 this is incorrect since host associated symbols, from any
+	 source, cannot be ambiguous with local symbols.  */
+      check_interface1 (sym->generic, sym->generic, 1, interface_name,
+			sym->attr.referenced || !sym->attr.use_assoc);
+    }
+}
+
+
+static void
+check_uop_interfaces (gfc_user_op *uop)
+{
+  char interface_name[100];
+  gfc_user_op *uop2;
+  gfc_namespace *ns;
+
+  sprintf (interface_name, "operator interface '%s'", uop->name);
+  if (check_interface0 (uop->op, interface_name))
+    return;
+
+  for (ns = gfc_current_ns; ns; ns = ns->parent)
+    {
+      uop2 = gfc_find_uop (uop->name, ns);
+      if (uop2 == NULL)
+	continue;
+
+      check_interface1 (uop->op, uop2->op, 0,
+			interface_name, true);
+    }
+}
+
+/* Given an intrinsic op, return an equivalent op if one exists,
+   or INTRINSIC_NONE otherwise.  */
+
+gfc_intrinsic_op
+gfc_equivalent_op (gfc_intrinsic_op op)
+{
+  switch(op)
+    {
+    case INTRINSIC_EQ:
+      return INTRINSIC_EQ_OS;
+
+    case INTRINSIC_EQ_OS:
+      return INTRINSIC_EQ;
+
+    case INTRINSIC_NE:
+      return INTRINSIC_NE_OS;
+
+    case INTRINSIC_NE_OS:
+      return INTRINSIC_NE;
+
+    case INTRINSIC_GT:
+      return INTRINSIC_GT_OS;
+
+    case INTRINSIC_GT_OS:
+      return INTRINSIC_GT;
+
+    case INTRINSIC_GE:
+      return INTRINSIC_GE_OS;
+
+    case INTRINSIC_GE_OS:
+      return INTRINSIC_GE;
+
+    case INTRINSIC_LT:
+      return INTRINSIC_LT_OS;
+
+    case INTRINSIC_LT_OS:
+      return INTRINSIC_LT;
+
+    case INTRINSIC_LE:
+      return INTRINSIC_LE_OS;
+
+    case INTRINSIC_LE_OS:
+      return INTRINSIC_LE;
+
+    default:
+      return INTRINSIC_NONE;
+    }
+}
+
+/* For the namespace, check generic, user operator and intrinsic
+   operator interfaces for consistency and to remove duplicate
+   interfaces.  We traverse the whole namespace, counting on the fact
+   that most symbols will not have generic or operator interfaces.  */
+
+void
+gfc_check_interfaces (gfc_namespace *ns)
+{
+  gfc_namespace *old_ns, *ns2;
+  char interface_name[100];
+  int i;
+
+  old_ns = gfc_current_ns;
+  gfc_current_ns = ns;
+
+  gfc_traverse_ns (ns, check_sym_interfaces);
+
+  gfc_traverse_user_op (ns, check_uop_interfaces);
+
+  for (i = GFC_INTRINSIC_BEGIN; i != GFC_INTRINSIC_END; i++)
+    {
+      if (i == INTRINSIC_USER)
+	continue;
+
+      if (i == INTRINSIC_ASSIGN)
+	strcpy (interface_name, "intrinsic assignment operator");
+      else
+	sprintf (interface_name, "intrinsic '%s' operator",
+		 gfc_op2string ((gfc_intrinsic_op) i));
+
+      if (check_interface0 (ns->op[i], interface_name))
+	continue;
+
+      if (ns->op[i])
+	gfc_check_operator_interface (ns->op[i]->sym, (gfc_intrinsic_op) i,
+				      ns->op[i]->where);
+
+      for (ns2 = ns; ns2; ns2 = ns2->parent)
+	{
+	  gfc_intrinsic_op other_op;
+
+	  if (check_interface1 (ns->op[i], ns2->op[i], 0,
+				interface_name, true))
+	    goto done;
+
+	  /* i should be gfc_intrinsic_op, but has to be int with this cast
+	     here for stupid C++ compatibility rules.  */
+	  other_op = gfc_equivalent_op ((gfc_intrinsic_op) i);
+	  if (other_op != INTRINSIC_NONE
+	    &&  check_interface1 (ns->op[i], ns2->op[other_op],
+				  0, interface_name, true))
+	    goto done;
+	}
+    }
+
+done:
+  gfc_current_ns = old_ns;
+}
+
+
+static int
+symbol_rank (gfc_symbol *sym)
+{
+  if (sym->ts.type == BT_CLASS && CLASS_DATA (sym)->as)
+    return CLASS_DATA (sym)->as->rank;
+
+  return (sym->as == NULL) ? 0 : sym->as->rank;
+}
+
+
+/* Given a symbol of a formal argument list and an expression, if the
+   formal argument is allocatable, check that the actual argument is
+   allocatable. Returns nonzero if compatible, zero if not compatible.  */
+
+static int
+compare_allocatable (gfc_symbol *formal, gfc_expr *actual)
+{
+  symbol_attribute attr;
+
+  if (formal->attr.allocatable
+      || (formal->ts.type == BT_CLASS && CLASS_DATA (formal)->attr.allocatable))
+    {
+      attr = gfc_expr_attr (actual);
+      if (!attr.allocatable)
+	return 0;
+    }
+
+  return 1;
+}
+
+
+/* Given a symbol of a formal argument list and an expression, if the
+   formal argument is a pointer, see if the actual argument is a
+   pointer. Returns nonzero if compatible, zero if not compatible.  */
+
+static int
+compare_pointer (gfc_symbol *formal, gfc_expr *actual)
+{
+  symbol_attribute attr;
+
+  if (formal->attr.pointer
+      || (formal->ts.type == BT_CLASS && CLASS_DATA (formal)
+	  && CLASS_DATA (formal)->attr.class_pointer))
+    {
+      attr = gfc_expr_attr (actual);
+
+      /* Fortran 2008 allows non-pointer actual arguments.  */
+      if (!attr.pointer && attr.target && formal->attr.intent == INTENT_IN)
+	return 2;
+
+      if (!attr.pointer)
+	return 0;
+    }
+
+  return 1;
+}
+
+
+/* Emit clear error messages for rank mismatch.  */
+
+static void
+argument_rank_mismatch (const char *name, locus *where,
+			int rank1, int rank2)
+{
+
+  /* TS 29113, C407b.  */
+  if (rank2 == -1)
+    {
+      gfc_error ("The assumed-rank array at %L requires that the dummy argument"
+		 " '%s' has assumed-rank", where, name);
+    }
+  else if (rank1 == 0)
+    {
+      gfc_error ("Rank mismatch in argument '%s' at %L "
+		 "(scalar and rank-%d)", name, where, rank2);
+    }
+  else if (rank2 == 0)
+    {
+      gfc_error ("Rank mismatch in argument '%s' at %L "
+		 "(rank-%d and scalar)", name, where, rank1);
+    }
+  else
+    {
+      gfc_error ("Rank mismatch in argument '%s' at %L "
+		 "(rank-%d and rank-%d)", name, where, rank1, rank2);
+    }
+}
+
+
+/* Given a symbol of a formal argument list and an expression, see if
+   the two are compatible as arguments.  Returns nonzero if
+   compatible, zero if not compatible.  */
+
+static int
+compare_parameter (gfc_symbol *formal, gfc_expr *actual,
+		   int ranks_must_agree, int is_elemental, locus *where)
+{
+  gfc_ref *ref;
+  bool rank_check, is_pointer;
+
+  /* If the formal arg has type BT_VOID, it's to one of the iso_c_binding
+     procs c_f_pointer or c_f_procpointer, and we need to accept most
+     pointers the user could give us.  This should allow that.  */
+  if (formal->ts.type == BT_VOID)
+    return 1;
+
+  if (formal->ts.type == BT_DERIVED
+      && formal->ts.u.derived && formal->ts.u.derived->ts.is_iso_c
+      && actual->ts.type == BT_DERIVED
+      && actual->ts.u.derived && actual->ts.u.derived->ts.is_iso_c)
+    return 1;
+
+  if (formal->ts.type == BT_CLASS && actual->ts.type == BT_DERIVED)
+    /* Make sure the vtab symbol is present when
+       the module variables are generated.  */
+    gfc_find_derived_vtab (actual->ts.u.derived);
+
+  if (actual->ts.type == BT_PROCEDURE)
+    {
+      char err[200];
+      gfc_symbol *act_sym = actual->symtree->n.sym;
+
+      if (formal->attr.flavor != FL_PROCEDURE)
+	{
+	  if (where)
+	    gfc_error ("Invalid procedure argument at %L", &actual->where);
+	  return 0;
+	}
+
+      if (!gfc_compare_interfaces (formal, act_sym, act_sym->name, 0, 1, err,
+				   sizeof(err), NULL, NULL))
+	{
+	  if (where)
+	    gfc_error ("Interface mismatch in dummy procedure '%s' at %L: %s",
+		       formal->name, &actual->where, err);
+	  return 0;
+	}
+
+      if (formal->attr.function && !act_sym->attr.function)
+	{
+	  gfc_add_function (&act_sym->attr, act_sym->name,
+	  &act_sym->declared_at);
+	  if (act_sym->ts.type == BT_UNKNOWN
+	      && gfc_set_default_type (act_sym, 1, act_sym->ns) == FAILURE)
+	    return 0;
+	}
+      else if (formal->attr.subroutine && !act_sym->attr.subroutine)
+	gfc_add_subroutine (&act_sym->attr, act_sym->name,
+			    &act_sym->declared_at);
+
+      return 1;
+    }
+
+  /* F2008, C1241.  */
+  if (formal->attr.pointer && formal->attr.contiguous
+      && !gfc_is_simply_contiguous (actual, true))
+    {
+      if (where)
+	gfc_error ("Actual argument to contiguous pointer dummy '%s' at %L "
+		   "must be simply contiguous", formal->name, &actual->where);
+      return 0;
+    }
+
+  if ((actual->expr_type != EXPR_NULL || actual->ts.type != BT_UNKNOWN)
+      && actual->ts.type != BT_HOLLERITH
+      && formal->ts.type != BT_ASSUMED
+      && !gfc_compare_types (&formal->ts, &actual->ts)
+      && !(formal->ts.type == BT_DERIVED && actual->ts.type == BT_CLASS
+	   && gfc_compare_derived_types (formal->ts.u.derived,
+					 CLASS_DATA (actual)->ts.u.derived)))
+    {
+      if (where)
+	gfc_error ("Type mismatch in argument '%s' at %L; passed %s to %s",
+		   formal->name, &actual->where, gfc_typename (&actual->ts),
+		   gfc_typename (&formal->ts));
+      return 0;
+    }
+
+  /* F2008, 12.5.2.5; IR F08/0073.  */
+  if (formal->ts.type == BT_CLASS && actual->expr_type != EXPR_NULL
+      && ((CLASS_DATA (formal)->attr.class_pointer
+	   && !formal->attr.intent == INTENT_IN)
+          || CLASS_DATA (formal)->attr.allocatable))
+    {
+      if (actual->ts.type != BT_CLASS)
+	{
+	  if (where)
+	    gfc_error ("Actual argument to '%s' at %L must be polymorphic",
+			formal->name, &actual->where);
+	  return 0;
+	}
+      if (!gfc_compare_derived_types (CLASS_DATA (actual)->ts.u.derived,
+				      CLASS_DATA (formal)->ts.u.derived))
+	{
+	  if (where)
+	    gfc_error ("Actual argument to '%s' at %L must have the same "
+		       "declared type", formal->name, &actual->where);
+	  return 0;
+	}
+    }
+
+  /* F08: 12.5.2.5 Allocatable and pointer dummy variables.  However, this
+     is necessary also for F03, so retain error for both.
+     NOTE: Other type/kind errors pre-empt this error.  Since they are F03
+     compatible, no attempt has been made to channel to this one.  */
+  if (UNLIMITED_POLY (formal) && !UNLIMITED_POLY (actual)
+      && (CLASS_DATA (formal)->attr.allocatable
+	  ||CLASS_DATA (formal)->attr.class_pointer))
+    {
+      if (where)
+	gfc_error ("Actual argument to '%s' at %L must be unlimited "
+		   "polymorphic since the formal argument is a "
+		   "pointer or allocatable unlimited polymorphic "
+		   "entity [F2008: 12.5.2.5]", formal->name,
+		   &actual->where);
+      return 0;
+    }
+
+  if (formal->attr.codimension && !gfc_is_coarray (actual))
+    {
+      if (where)
+	gfc_error ("Actual argument to '%s' at %L must be a coarray",
+		       formal->name, &actual->where);
+      return 0;
+    }
+
+  if (formal->attr.codimension && formal->attr.allocatable)
+    {
+      gfc_ref *last = NULL;
+
+      for (ref = actual->ref; ref; ref = ref->next)
+	if (ref->type == REF_COMPONENT)
+	  last = ref;
+
+      /* F2008, 12.5.2.6.  */
+      if ((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 (formal->attr.codimension)
+    {
+      /* F2008, 12.5.2.8.  */
+      if (formal->attr.dimension
+	  && (formal->attr.contiguous || formal->as->type != AS_ASSUMED_SHAPE)
+	  && gfc_expr_attr (actual).dimension
+	  && !gfc_is_simply_contiguous (actual, true))
+	{
+	  if (where)
+	    gfc_error ("Actual argument to '%s' at %L must be simply "
+		       "contiguous", formal->name, &actual->where);
+	  return 0;
+	}
+
+      /* F2008, C1303 and C1304.  */
+      if (formal->attr.intent != INTENT_INOUT
+	  && (((formal->ts.type == BT_DERIVED || formal->ts.type == BT_CLASS)
+	       && formal->ts.u.derived->from_intmod == INTMOD_ISO_FORTRAN_ENV
+	       && formal->ts.u.derived->intmod_sym_id == ISOFORTRAN_LOCK_TYPE)
+	      || formal->attr.lock_comp))
+
+    	{
+	  if (where)
+	    gfc_error ("Actual argument to non-INTENT(INOUT) dummy '%s' at %L, "
+		       "which is LOCK_TYPE or has a LOCK_TYPE component",
+		       formal->name, &actual->where);
+	  return 0;
+	}
+    }
+
+  /* F2008, C1239/C1240.  */
+  if (actual->expr_type == EXPR_VARIABLE
+      && (actual->symtree->n.sym->attr.asynchronous
+         || actual->symtree->n.sym->attr.volatile_)
+      &&  (formal->attr.asynchronous || formal->attr.volatile_)
+      && actual->rank && !gfc_is_simply_contiguous (actual, true)
+      && ((formal->as->type != AS_ASSUMED_SHAPE && !formal->attr.pointer)
+	  || formal->attr.contiguous))
+    {
+      if (where)
+	gfc_error ("Dummy argument '%s' has to be a pointer or assumed-shape "
+		   "array without CONTIGUOUS attribute - as actual argument at"
+		   " %L is not simply contiguous and both are ASYNCHRONOUS "
+		   "or VOLATILE", formal->name, &actual->where);
+      return 0;
+    }
+
+  if (formal->attr.allocatable && !formal->attr.codimension
+      && gfc_expr_attr (actual).codimension)
+    {
+      if (formal->attr.intent == INTENT_OUT)
+	{
+	  if (where)
+	    gfc_error ("Passing coarray at %L to allocatable, noncoarray, "
+		       "INTENT(OUT) dummy argument '%s'", &actual->where,
+		       formal->name);
+	    return 0;
+	}
+      else if (gfc_option.warn_surprising && where
+	       && formal->attr.intent != INTENT_IN)
+	gfc_warning ("Passing coarray at %L to allocatable, noncoarray dummy "
+		     "argument '%s', which is invalid if the allocation status"
+		     " is modified",  &actual->where, formal->name);
+    }
+
+  /* If the rank is the same or the formal argument has assumed-rank.  */
+  if (symbol_rank (formal) == actual->rank || symbol_rank (formal) == -1)
+    return 1;
+
+  if (actual->ts.type == BT_CLASS && CLASS_DATA (actual)->as
+	&& CLASS_DATA (actual)->as->rank == symbol_rank (formal))
+    return 1;
+
+  rank_check = where != NULL && !is_elemental && formal->as
+	       && (formal->as->type == AS_ASSUMED_SHAPE
+		   || 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->ts.type == BT_CLASS
+	       && CLASS_DATA (formal)->as->type == AS_ASSUMED_SHAPE)
+	      || (formal->ts.type != BT_CLASS
+		   && formal->as->type == AS_ASSUMED_SHAPE))
+	  && actual->expr_type != EXPR_NULL)
+      || (actual->rank == 0 && formal->attr.dimension
+	  && gfc_is_coindexed (actual)))
+    {
+      if (where)
+	argument_rank_mismatch (formal->name, &actual->where,
+				symbol_rank (formal), actual->rank);
+      return 0;
+    }
+  else if (actual->rank != 0 && (is_elemental || formal->attr.dimension))
+    return 1;
+
+  /* At this point, we are considering a scalar passed to an array.   This
+     is valid (cf. F95 12.4.1.1, F2003 12.4.1.2, and F2008 12.5.2.4),
+     - if the actual argument is (a substring of) an element of a
+       non-assumed-shape/non-pointer/non-polymorphic array; or
+     - (F2003) if the actual argument is of type character of default/c_char
+       kind.  */
+
+  is_pointer = actual->expr_type == EXPR_VARIABLE
+	       ? actual->symtree->n.sym->attr.pointer : false;
+
+  for (ref = actual->ref; ref; ref = ref->next)
+    {
+      if (ref->type == REF_COMPONENT)
+	is_pointer = ref->u.c.component->attr.pointer;
+      else if (ref->type == REF_ARRAY && ref->u.ar.type == AR_ELEMENT
+	       && ref->u.ar.dimen > 0
+	       && (!ref->next
+		   || (ref->next->type == REF_SUBSTRING && !ref->next->next)))
+        break;
+    }
+
+  if (actual->ts.type == BT_CLASS && actual->expr_type != EXPR_NULL)
+    {
+      if (where)
+	gfc_error ("Polymorphic scalar passed to array dummy argument '%s' "
+		   "at %L", formal->name, &actual->where);
+      return 0;
+    }
+
+  if (actual->expr_type != EXPR_NULL && ref && actual->ts.type != BT_CHARACTER
+      && (is_pointer || ref->u.ar.as->type == AS_ASSUMED_SHAPE))
+    {
+      if (where)
+	gfc_error ("Element of assumed-shaped or pointer "
+		   "array passed to array dummy argument '%s' at %L",
+		   formal->name, &actual->where);
+      return 0;
+    }
+
+  if (actual->ts.type == BT_CHARACTER && actual->expr_type != EXPR_NULL
+      && (!ref || is_pointer || ref->u.ar.as->type == AS_ASSUMED_SHAPE))
+    {
+      if (formal->ts.kind != 1 && (gfc_option.allow_std & GFC_STD_GNU) == 0)
+	{
+	  if (where)
+	    gfc_error ("Extension: Scalar non-default-kind, non-C_CHAR-kind "
+		       "CHARACTER actual argument with array dummy argument "
+		       "'%s' at %L", formal->name, &actual->where);
+	  return 0;
+	}
+
+      if (where && (gfc_option.allow_std & GFC_STD_F2003) == 0)
+	{
+	  gfc_error ("Fortran 2003: Scalar CHARACTER actual argument with "
+		     "array dummy argument '%s' at %L",
+		     formal->name, &actual->where);
+	  return 0;
+	}
+      else if ((gfc_option.allow_std & GFC_STD_F2003) == 0)
+	return 0;
+      else
+	return 1;
+    }
+
+  if (ref == NULL && actual->expr_type != EXPR_NULL)
+    {
+      if (where)
+	argument_rank_mismatch (formal->name, &actual->where,
+				symbol_rank (formal), actual->rank);
+      return 0;
+    }
+
+  return 1;
+}
+
+
+/* Returns the storage size of a symbol (formal argument) or
+   zero if it cannot be determined.  */
+
+static unsigned long
+get_sym_storage_size (gfc_symbol *sym)
+{
+  int i;
+  unsigned long strlen, elements;
+
+  if (sym->ts.type == BT_CHARACTER)
+    {
+      if (sym->ts.u.cl && sym->ts.u.cl->length
+          && sym->ts.u.cl->length->expr_type == EXPR_CONSTANT)
+	strlen = mpz_get_ui (sym->ts.u.cl->length->value.integer);
+      else
+	return 0;
+    }
+  else
+    strlen = 1;
+
+  if (symbol_rank (sym) == 0)
+    return strlen;
+
+  elements = 1;
+  if (sym->as->type != AS_EXPLICIT)
+    return 0;
+  for (i = 0; i < sym->as->rank; i++)
+    {
+      if (sym->as->upper[i]->expr_type != EXPR_CONSTANT
+	  || sym->as->lower[i]->expr_type != EXPR_CONSTANT)
+	return 0;
+
+      elements *= mpz_get_si (sym->as->upper[i]->value.integer)
+		  - mpz_get_si (sym->as->lower[i]->value.integer) + 1L;
+    }
+
+  return strlen*elements;
+}
+
+
+/* Returns the storage size of an expression (actual argument) or
+   zero if it cannot be determined. For an array element, it returns
+   the remaining size as the element sequence consists of all storage
+   units of the actual argument up to the end of the array.  */
+
+static unsigned long
+get_expr_storage_size (gfc_expr *e)
+{
+  int i;
+  long int strlen, elements;
+  long int substrlen = 0;
+  bool is_str_storage = false;
+  gfc_ref *ref;
+
+  if (e == NULL)
+    return 0;
+
+  if (e->ts.type == BT_CHARACTER)
+    {
+      if (e->ts.u.cl && e->ts.u.cl->length
+          && e->ts.u.cl->length->expr_type == EXPR_CONSTANT)
+	strlen = mpz_get_si (e->ts.u.cl->length->value.integer);
+      else if (e->expr_type == EXPR_CONSTANT
+	       && (e->ts.u.cl == NULL || e->ts.u.cl->length == NULL))
+	strlen = e->value.character.length;
+      else
+	return 0;
+    }
+  else
+    strlen = 1; /* Length per element.  */
+
+  if (e->rank == 0 && !e->ref)
+    return strlen;
+
+  elements = 1;
+  if (!e->ref)
+    {
+      if (!e->shape)
+	return 0;
+      for (i = 0; i < e->rank; i++)
+	elements *= mpz_get_si (e->shape[i]);
+      return elements*strlen;
+    }
+
+  for (ref = e->ref; ref; ref = ref->next)
+    {
+      if (ref->type == REF_SUBSTRING && ref->u.ss.start
+	  && ref->u.ss.start->expr_type == EXPR_CONSTANT)
+	{
+	  if (is_str_storage)
+	    {
+	      /* The string length is the substring length.
+		 Set now to full string length.  */
+	      if (!ref->u.ss.length || !ref->u.ss.length->length
+		  || ref->u.ss.length->length->expr_type != EXPR_CONSTANT)
+		return 0;
+
+	      strlen = mpz_get_ui (ref->u.ss.length->length->value.integer);
+	    }
+	  substrlen = strlen - mpz_get_ui (ref->u.ss.start->value.integer) + 1;
+	  continue;
+	}
+
+      if (ref->type == REF_ARRAY && ref->u.ar.type == AR_SECTION)
+	for (i = 0; i < ref->u.ar.dimen; i++)
+	  {
+	    long int start, end, stride;
+	    stride = 1;
+
+	    if (ref->u.ar.stride[i])
+	      {
+		if (ref->u.ar.stride[i]->expr_type == EXPR_CONSTANT)
+		  stride = mpz_get_si (ref->u.ar.stride[i]->value.integer);
+		else
+		  return 0;
+	      }
+
+	    if (ref->u.ar.start[i])
+	      {
+		if (ref->u.ar.start[i]->expr_type == EXPR_CONSTANT)
+		  start = mpz_get_si (ref->u.ar.start[i]->value.integer);
+		else
+		  return 0;
+	      }
+	    else if (ref->u.ar.as->lower[i]
+		     && ref->u.ar.as->lower[i]->expr_type == EXPR_CONSTANT)
+	      start = mpz_get_si (ref->u.ar.as->lower[i]->value.integer);
+	    else
+	      return 0;
+
+	    if (ref->u.ar.end[i])
+	      {
+		if (ref->u.ar.end[i]->expr_type == EXPR_CONSTANT)
+		  end = mpz_get_si (ref->u.ar.end[i]->value.integer);
+		else
+		  return 0;
+	      }
+	    else if (ref->u.ar.as->upper[i]
+		     && ref->u.ar.as->upper[i]->expr_type == EXPR_CONSTANT)
+	      end = mpz_get_si (ref->u.ar.as->upper[i]->value.integer);
+	    else
+	      return 0;
+
+	    elements *= (end - start)/stride + 1L;
+	  }
+      else if (ref->type == REF_ARRAY && ref->u.ar.type == AR_FULL)
+	for (i = 0; i < ref->u.ar.as->rank; i++)
+	  {
+	    if (ref->u.ar.as->lower[i] && ref->u.ar.as->upper[i]
+		&& ref->u.ar.as->lower[i]->expr_type == EXPR_CONSTANT
+		&& ref->u.ar.as->upper[i]->expr_type == EXPR_CONSTANT)
+	      elements *= mpz_get_si (ref->u.ar.as->upper[i]->value.integer)
+			  - mpz_get_si (ref->u.ar.as->lower[i]->value.integer)
+			  + 1L;
+	    else
+	      return 0;
+	  }
+      else if (ref->type == REF_ARRAY && ref->u.ar.type == AR_ELEMENT
+	       && e->expr_type == EXPR_VARIABLE)
+	{
+	  if (ref->u.ar.as->type == AS_ASSUMED_SHAPE
+	      || e->symtree->n.sym->attr.pointer)
+	    {
+	      elements = 1;
+	      continue;
+	    }
+
+	  /* Determine the number of remaining elements in the element
+	     sequence for array element designators.  */
+	  is_str_storage = true;
+	  for (i = ref->u.ar.dimen - 1; i >= 0; i--)
+	    {
+	      if (ref->u.ar.start[i] == NULL
+		  || ref->u.ar.start[i]->expr_type != EXPR_CONSTANT
+		  || ref->u.ar.as->upper[i] == NULL
+		  || ref->u.ar.as->lower[i] == NULL
+		  || ref->u.ar.as->upper[i]->expr_type != EXPR_CONSTANT
+		  || ref->u.ar.as->lower[i]->expr_type != EXPR_CONSTANT)
+		return 0;
+
+	      elements
+		   = elements
+		     * (mpz_get_si (ref->u.ar.as->upper[i]->value.integer)
+			- mpz_get_si (ref->u.ar.as->lower[i]->value.integer)
+			+ 1L)
+		     - (mpz_get_si (ref->u.ar.start[i]->value.integer)
+			- mpz_get_si (ref->u.ar.as->lower[i]->value.integer));
+	    }
+        }
+    }
+
+  if (substrlen)
+    return (is_str_storage) ? substrlen + (elements-1)*strlen
+			    : elements*strlen;
+  else
+    return elements*strlen;
+}
+
+
+/* Given an expression, check whether it is an array section
+   which has a vector subscript. If it has, one is returned,
+   otherwise zero.  */
+
+int
+gfc_has_vector_subscript (gfc_expr *e)
+{
+  int i;
+  gfc_ref *ref;
+
+  if (e == NULL || e->rank == 0 || e->expr_type != EXPR_VARIABLE)
+    return 0;
+
+  for (ref = e->ref; ref; ref = ref->next)
+    if (ref->type == REF_ARRAY && ref->u.ar.type == AR_SECTION)
+      for (i = 0; i < ref->u.ar.dimen; i++)
+	if (ref->u.ar.dimen_type[i] == DIMEN_VECTOR)
+	  return 1;
+
+  return 0;
+}
+
+
+/* Given formal and actual argument lists, see if they are compatible.
+   If they are compatible, the actual argument list is sorted to
+   correspond with the formal list, and elements for missing optional
+   arguments are inserted. If WHERE pointer is nonnull, then we issue
+   errors when things don't match instead of just returning the status
+   code.  */
+
+static int
+compare_actual_formal (gfc_actual_arglist **ap, gfc_formal_arglist *formal,
+	 	       int ranks_must_agree, int is_elemental, locus *where)
+{
+  gfc_actual_arglist **new_arg, *a, *actual, temp;
+  gfc_formal_arglist *f;
+  int i, n, na;
+  unsigned long actual_size, formal_size;
+  bool full_array = false;
+
+  actual = *ap;
+
+  if (actual == NULL && formal == NULL)
+    return 1;
+
+  n = 0;
+  for (f = formal; f; f = f->next)
+    n++;
+
+  new_arg = XALLOCAVEC (gfc_actual_arglist *, n);
+
+  for (i = 0; i < n; i++)
+    new_arg[i] = NULL;
+
+  na = 0;
+  f = formal;
+  i = 0;
+
+  for (a = actual; a; a = a->next, f = f->next)
+    {
+      /* Look for keywords but ignore g77 extensions like %VAL.  */
+      if (a->name != NULL && a->name[0] != '%')
+	{
+	  i = 0;
+	  for (f = formal; f; f = f->next, i++)
+	    {
+	      if (f->sym == NULL)
+		continue;
+	      if (strcmp (f->sym->name, a->name) == 0)
+		break;
+	    }
+
+	  if (f == NULL)
+	    {
+	      if (where)
+		gfc_error ("Keyword argument '%s' at %L is not in "
+			   "the procedure", a->name, &a->expr->where);
+	      return 0;
+	    }
+
+	  if (new_arg[i] != NULL)
+	    {
+	      if (where)
+		gfc_error ("Keyword argument '%s' at %L is already associated "
+			   "with another actual argument", a->name,
+			   &a->expr->where);
+	      return 0;
+	    }
+	}
+
+      if (f == NULL)
+	{
+	  if (where)
+	    gfc_error ("More actual than formal arguments in procedure "
+		       "call at %L", where);
+
+	  return 0;
+	}
+
+      if (f->sym == NULL && a->expr == NULL)
+	goto match;
+
+      if (f->sym == NULL)
+	{
+	  if (where)
+	    gfc_error ("Missing alternate return spec in subroutine call "
+		       "at %L", where);
+	  return 0;
+	}
+
+      if (a->expr == NULL)
+	{
+	  if (where)
+	    gfc_error ("Unexpected alternate return spec in subroutine "
+		       "call at %L", where);
+	  return 0;
+	}
+
+      /* Make sure that intrinsic vtables exist for calls to unlimited
+	 polymorphic formal arguments.  */
+      if (UNLIMITED_POLY(f->sym)
+	  && a->expr->ts.type != BT_DERIVED
+	  && a->expr->ts.type != BT_CLASS)
+	gfc_find_intrinsic_vtab (&a->expr->ts);
+
+      if (a->expr->expr_type == EXPR_NULL
+	  && ((f->sym->ts.type != BT_CLASS && !f->sym->attr.pointer
+	       && (f->sym->attr.allocatable || !f->sym->attr.optional
+		   || (gfc_option.allow_std & GFC_STD_F2008) == 0))
+	      || (f->sym->ts.type == BT_CLASS
+		  && !CLASS_DATA (f->sym)->attr.class_pointer
+		  && (CLASS_DATA (f->sym)->attr.allocatable
+		      || !f->sym->attr.optional
+		      || (gfc_option.allow_std & GFC_STD_F2008) == 0))))
+	{
+	  if (where
+	      && (!f->sym->attr.optional
+		  || (f->sym->ts.type != BT_CLASS && f->sym->attr.allocatable)
+		  || (f->sym->ts.type == BT_CLASS
+			 && CLASS_DATA (f->sym)->attr.allocatable)))
+	    gfc_error ("Unexpected NULL() intrinsic at %L to dummy '%s'",
+		       where, f->sym->name);
+	  else if (where)
+	    gfc_error ("Fortran 2008: Null pointer at %L to non-pointer "
+		       "dummy '%s'", where, f->sym->name);
+
+	  return 0;
+	}
+
+      if (!compare_parameter (f->sym, a->expr, ranks_must_agree,
+			      is_elemental, where))
+	return 0;
+
+      /* TS 29113, 6.3p2.  */
+      if (f->sym->ts.type == BT_ASSUMED
+	  && (a->expr->ts.type == BT_DERIVED
+	      || (a->expr->ts.type == BT_CLASS && CLASS_DATA (a->expr))))
+	{
+	  gfc_namespace *f2k_derived;
+
+	  f2k_derived = a->expr->ts.type == BT_DERIVED
+			? a->expr->ts.u.derived->f2k_derived
+			: CLASS_DATA (a->expr)->ts.u.derived->f2k_derived;
+
+	  if (f2k_derived
+	      && (f2k_derived->finalizers || f2k_derived->tb_sym_root))
+	    {
+	      gfc_error ("Actual argument at %L to assumed-type dummy is of "
+			 "derived type with type-bound or FINAL procedures",
+			 &a->expr->where);
+	      return FAILURE;
+	    }
+	}
+
+      /* Special case for character arguments.  For allocatable, pointer
+	 and assumed-shape dummies, the string length needs to match
+	 exactly.  */
+      if (a->expr->ts.type == BT_CHARACTER
+	   && a->expr->ts.u.cl && a->expr->ts.u.cl->length
+	   && a->expr->ts.u.cl->length->expr_type == EXPR_CONSTANT
+	   && f->sym->ts.u.cl && f->sym->ts.u.cl && f->sym->ts.u.cl->length
+	   && f->sym->ts.u.cl->length->expr_type == EXPR_CONSTANT
+	   && (f->sym->attr.pointer || f->sym->attr.allocatable
+	       || (f->sym->as && f->sym->as->type == AS_ASSUMED_SHAPE))
+	   && (mpz_cmp (a->expr->ts.u.cl->length->value.integer,
+			f->sym->ts.u.cl->length->value.integer) != 0))
+	 {
+	   if (where && (f->sym->attr.pointer || f->sym->attr.allocatable))
+	     gfc_warning ("Character length mismatch (%ld/%ld) between actual "
+			  "argument and pointer or allocatable dummy argument "
+			  "'%s' at %L",
+			  mpz_get_si (a->expr->ts.u.cl->length->value.integer),
+			  mpz_get_si (f->sym->ts.u.cl->length->value.integer),
+			  f->sym->name, &a->expr->where);
+	   else if (where)
+	     gfc_warning ("Character length mismatch (%ld/%ld) between actual "
+			  "argument and assumed-shape dummy argument '%s' "
+			  "at %L",
+			  mpz_get_si (a->expr->ts.u.cl->length->value.integer),
+			  mpz_get_si (f->sym->ts.u.cl->length->value.integer),
+			  f->sym->name, &a->expr->where);
+	   return 0;
+	 }
+
+      if ((f->sym->attr.pointer || f->sym->attr.allocatable)
+	    && f->sym->ts.deferred != a->expr->ts.deferred
+	    && a->expr->ts.type == BT_CHARACTER)
+	{
+	  if (where)
+	    gfc_error ("Actual argument at %L to allocatable or "
+		       "pointer dummy argument '%s' must have a deferred "
+		       "length type parameter if and only if the dummy has one",
+		       &a->expr->where, f->sym->name);
+	  return 0;
+	}
+
+      if (f->sym->ts.type == BT_CLASS)
+	goto skip_size_check;
+
+      actual_size = get_expr_storage_size (a->expr);
+      formal_size = get_sym_storage_size (f->sym);
+      if (actual_size != 0 && actual_size < formal_size
+	  && a->expr->ts.type != BT_PROCEDURE
+	  && f->sym->attr.flavor != FL_PROCEDURE)
+	{
+	  if (a->expr->ts.type == BT_CHARACTER && !f->sym->as && where)
+	    gfc_warning ("Character length of actual argument shorter "
+			 "than of dummy argument '%s' (%lu/%lu) at %L",
+			 f->sym->name, actual_size, formal_size,
+			 &a->expr->where);
+          else if (where)
+	    gfc_warning ("Actual argument contains too few "
+			 "elements for dummy argument '%s' (%lu/%lu) at %L",
+			 f->sym->name, actual_size, formal_size,
+			 &a->expr->where);
+	  return  0;
+	}
+
+     skip_size_check:
+
+      /* Satisfy F03:12.4.1.3 by ensuring that a procedure pointer actual
+         argument is provided for a procedure pointer formal argument.  */
+      if (f->sym->attr.proc_pointer
+	  && !((a->expr->expr_type == EXPR_VARIABLE
+		&& a->expr->symtree->n.sym->attr.proc_pointer)
+	       || (a->expr->expr_type == EXPR_FUNCTION
+		   && a->expr->symtree->n.sym->result->attr.proc_pointer)
+	       || gfc_is_proc_ptr_comp (a->expr)))
+	{
+	  if (where)
+	    gfc_error ("Expected a procedure pointer for argument '%s' at %L",
+		       f->sym->name, &a->expr->where);
+	  return 0;
+	}
+
+      /* Satisfy F03:12.4.1.3 by ensuring that a procedure actual argument is
+	 provided for a procedure formal argument.  */
+      if (f->sym->attr.flavor == FL_PROCEDURE
+	  && gfc_expr_attr (a->expr).flavor != FL_PROCEDURE)
+	{
+	  if (where)
+	    gfc_error ("Expected a procedure for argument '%s' at %L",
+		       f->sym->name, &a->expr->where);
+	  return 0;
+	}
+
+      if (f->sym->as && f->sym->as->type == AS_ASSUMED_SHAPE
+	  && a->expr->expr_type == EXPR_VARIABLE
+	  && a->expr->symtree->n.sym->as
+	  && a->expr->symtree->n.sym->as->type == AS_ASSUMED_SIZE
+	  && (a->expr->ref == NULL
+	      || (a->expr->ref->type == REF_ARRAY
+		  && a->expr->ref->u.ar.type == AR_FULL)))
+	{
+	  if (where)
+	    gfc_error ("Actual argument for '%s' cannot be an assumed-size"
+		       " array at %L", f->sym->name, where);
+	  return 0;
+	}
+
+      if (a->expr->expr_type != EXPR_NULL
+	  && compare_pointer (f->sym, a->expr) == 0)
+	{
+	  if (where)
+	    gfc_error ("Actual argument for '%s' must be a pointer at %L",
+		       f->sym->name, &a->expr->where);
+	  return 0;
+	}
+
+      if (a->expr->expr_type != EXPR_NULL
+	  && (gfc_option.allow_std & GFC_STD_F2008) == 0
+	  && compare_pointer (f->sym, a->expr) == 2)
+	{
+	  if (where)
+	    gfc_error ("Fortran 2008: Non-pointer actual argument at %L to "
+		       "pointer dummy '%s'", &a->expr->where,f->sym->name);
+	  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 "
+		       "%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 (f->sym->ts.type == BT_CLASS
+	   && CLASS_DATA (f->sym)->attr.allocatable
+	   && gfc_is_class_array_ref (a->expr, &full_array)
+	   && !full_array)
+	{
+	  if (where)
+	    gfc_error ("Actual CLASS array argument for '%s' must be a full "
+		       "array at %L", f->sym->name, &a->expr->where);
+	  return 0;
+	}
+
+
+      if (a->expr->expr_type != EXPR_NULL
+	  && compare_allocatable (f->sym, a->expr) == 0)
+	{
+	  if (where)
+	    gfc_error ("Actual argument for '%s' must be ALLOCATABLE at %L",
+		       f->sym->name, &a->expr->where);
+	  return 0;
+	}
+
+      /* Check intent = OUT/INOUT for definable actual argument.  */
+      if ((f->sym->attr.intent == INTENT_OUT
+	  || f->sym->attr.intent == INTENT_INOUT))
+	{
+	  const char* context = (where
+				 ? _("actual argument to INTENT = OUT/INOUT")
+				 : NULL);
+
+	  if (((f->sym->ts.type == BT_CLASS && f->sym->attr.class_ok
+		&& CLASS_DATA (f->sym)->attr.class_pointer)
+	       || (f->sym->ts.type != BT_CLASS && f->sym->attr.pointer))
+	      && gfc_check_vardef_context (a->expr, true, false, false, context)
+		   == FAILURE)
+	    return 0;
+	  if (gfc_check_vardef_context (a->expr, false, false, false, context)
+		== FAILURE)
+	    return 0;
+	}
+
+      if ((f->sym->attr.intent == INTENT_OUT
+	   || f->sym->attr.intent == INTENT_INOUT
+	   || f->sym->attr.volatile_
+	   || f->sym->attr.asynchronous)
+	  && gfc_has_vector_subscript (a->expr))
+	{
+	  if (where)
+	    gfc_error ("Array-section actual argument with vector "
+		       "subscripts at %L is incompatible with INTENT(OUT), "
+		       "INTENT(INOUT), VOLATILE or ASYNCHRONOUS attribute "
+		       "of the dummy argument '%s'",
+		       &a->expr->where, f->sym->name);
+	  return 0;
+	}
+
+      /* C1232 (R1221) For an actual argument which is an array section or
+	 an assumed-shape array, the dummy argument shall be an assumed-
+	 shape array, if the dummy argument has the VOLATILE attribute.  */
+
+      if (f->sym->attr.volatile_
+	  && a->expr->symtree->n.sym->as
+	  && a->expr->symtree->n.sym->as->type == AS_ASSUMED_SHAPE
+	  && !(f->sym->as && f->sym->as->type == AS_ASSUMED_SHAPE))
+	{
+	  if (where)
+	    gfc_error ("Assumed-shape actual argument at %L is "
+		       "incompatible with the non-assumed-shape "
+		       "dummy argument '%s' due to VOLATILE attribute",
+		       &a->expr->where,f->sym->name);
+	  return 0;
+	}
+
+      if (f->sym->attr.volatile_
+	  && a->expr->ref && a->expr->ref->u.ar.type == AR_SECTION
+	  && !(f->sym->as && f->sym->as->type == AS_ASSUMED_SHAPE))
+	{
+	  if (where)
+	    gfc_error ("Array-section actual argument at %L is "
+		       "incompatible with the non-assumed-shape "
+		       "dummy argument '%s' due to VOLATILE attribute",
+		       &a->expr->where,f->sym->name);
+	  return 0;
+	}
+
+      /* C1233 (R1221) For an actual argument which is a pointer array, the
+	 dummy argument shall be an assumed-shape or pointer array, if the
+	 dummy argument has the VOLATILE attribute.  */
+
+      if (f->sym->attr.volatile_
+	  && a->expr->symtree->n.sym->attr.pointer
+	  && a->expr->symtree->n.sym->as
+	  && !(f->sym->as
+	       && (f->sym->as->type == AS_ASSUMED_SHAPE
+		   || f->sym->attr.pointer)))
+	{
+	  if (where)
+	    gfc_error ("Pointer-array actual argument at %L requires "
+		       "an assumed-shape or pointer-array dummy "
+		       "argument '%s' due to VOLATILE attribute",
+		       &a->expr->where,f->sym->name);
+	  return 0;
+	}
+
+    match:
+      if (a == actual)
+	na = i;
+
+      new_arg[i++] = a;
+    }
+
+  /* Make sure missing actual arguments are optional.  */
+  i = 0;
+  for (f = formal; f; f = f->next, i++)
+    {
+      if (new_arg[i] != NULL)
+	continue;
+      if (f->sym == NULL)
+	{
+	  if (where)
+	    gfc_error ("Missing alternate return spec in subroutine call "
+		       "at %L", where);
+	  return 0;
+	}
+      if (!f->sym->attr.optional)
+	{
+	  if (where)
+	    gfc_error ("Missing actual argument for argument '%s' at %L",
+		       f->sym->name, where);
+	  return 0;
+	}
+    }
+
+  /* The argument lists are compatible.  We now relink a new actual
+     argument list with null arguments in the right places.  The head
+     of the list remains the head.  */
+  for (i = 0; i < n; i++)
+    if (new_arg[i] == NULL)
+      new_arg[i] = gfc_get_actual_arglist ();
+
+  if (na != 0)
+    {
+      temp = *new_arg[0];
+      *new_arg[0] = *actual;
+      *actual = temp;
+
+      a = new_arg[0];
+      new_arg[0] = new_arg[na];
+      new_arg[na] = a;
+    }
+
+  for (i = 0; i < n - 1; i++)
+    new_arg[i]->next = new_arg[i + 1];
+
+  new_arg[i]->next = NULL;
+
+  if (*ap == NULL && n > 0)
+    *ap = new_arg[0];
+
+  /* Note the types of omitted optional arguments.  */
+  for (a = *ap, f = formal; a; a = a->next, f = f->next)
+    if (a->expr == NULL && a->label == NULL)
+      a->missing_arg_type = f->sym->ts.type;
+
+  return 1;
+}
+
+
+typedef struct
+{
+  gfc_formal_arglist *f;
+  gfc_actual_arglist *a;
+}
+argpair;
+
+/* qsort comparison function for argument pairs, with the following
+   order:
+    - p->a->expr == NULL
+    - p->a->expr->expr_type != EXPR_VARIABLE
+    - growing p->a->expr->symbol.  */
+
+static int
+pair_cmp (const void *p1, const void *p2)
+{
+  const gfc_actual_arglist *a1, *a2;
+
+  /* *p1 and *p2 are elements of the to-be-sorted array.  */
+  a1 = ((const argpair *) p1)->a;
+  a2 = ((const argpair *) p2)->a;
+  if (!a1->expr)
+    {
+      if (!a2->expr)
+	return 0;
+      return -1;
+    }
+  if (!a2->expr)
+    return 1;
+  if (a1->expr->expr_type != EXPR_VARIABLE)
+    {
+      if (a2->expr->expr_type != EXPR_VARIABLE)
+	return 0;
+      return -1;
+    }
+  if (a2->expr->expr_type != EXPR_VARIABLE)
+    return 1;
+  return a1->expr->symtree->n.sym < a2->expr->symtree->n.sym;
+}
+
+
+/* Given two expressions from some actual arguments, test whether they
+   refer to the same expression. The analysis is conservative.
+   Returning FAILURE will produce no warning.  */
+
+static gfc_try
+compare_actual_expr (gfc_expr *e1, gfc_expr *e2)
+{
+  const gfc_ref *r1, *r2;
+
+  if (!e1 || !e2
+      || e1->expr_type != EXPR_VARIABLE
+      || e2->expr_type != EXPR_VARIABLE
+      || e1->symtree->n.sym != e2->symtree->n.sym)
+    return FAILURE;
+
+  /* TODO: improve comparison, see expr.c:show_ref().  */
+  for (r1 = e1->ref, r2 = e2->ref; r1 && r2; r1 = r1->next, r2 = r2->next)
+    {
+      if (r1->type != r2->type)
+	return FAILURE;
+      switch (r1->type)
+	{
+	case REF_ARRAY:
+	  if (r1->u.ar.type != r2->u.ar.type)
+	    return FAILURE;
+	  /* TODO: At the moment, consider only full arrays;
+	     we could do better.  */
+	  if (r1->u.ar.type != AR_FULL || r2->u.ar.type != AR_FULL)
+	    return FAILURE;
+	  break;
+
+	case REF_COMPONENT:
+	  if (r1->u.c.component != r2->u.c.component)
+	    return FAILURE;
+	  break;
+
+	case REF_SUBSTRING:
+	  return FAILURE;
+
+	default:
+	  gfc_internal_error ("compare_actual_expr(): Bad component code");
+	}
+    }
+  if (!r1 && !r2)
+    return SUCCESS;
+  return FAILURE;
+}
+
+
+/* Given formal and actual argument lists that correspond to one
+   another, check that identical actual arguments aren't not
+   associated with some incompatible INTENTs.  */
+
+static gfc_try
+check_some_aliasing (gfc_formal_arglist *f, gfc_actual_arglist *a)
+{
+  sym_intent f1_intent, f2_intent;
+  gfc_formal_arglist *f1;
+  gfc_actual_arglist *a1;
+  size_t n, i, j;
+  argpair *p;
+  gfc_try t = SUCCESS;
+
+  n = 0;
+  for (f1 = f, a1 = a;; f1 = f1->next, a1 = a1->next)
+    {
+      if (f1 == NULL && a1 == NULL)
+	break;
+      if (f1 == NULL || a1 == NULL)
+	gfc_internal_error ("check_some_aliasing(): List mismatch");
+      n++;
+    }
+  if (n == 0)
+    return t;
+  p = XALLOCAVEC (argpair, n);
+
+  for (i = 0, f1 = f, a1 = a; i < n; i++, f1 = f1->next, a1 = a1->next)
+    {
+      p[i].f = f1;
+      p[i].a = a1;
+    }
+
+  qsort (p, n, sizeof (argpair), pair_cmp);
+
+  for (i = 0; i < n; i++)
+    {
+      if (!p[i].a->expr
+	  || p[i].a->expr->expr_type != EXPR_VARIABLE
+	  || p[i].a->expr->ts.type == BT_PROCEDURE)
+	continue;
+      f1_intent = p[i].f->sym->attr.intent;
+      for (j = i + 1; j < n; j++)
+	{
+	  /* Expected order after the sort.  */
+	  if (!p[j].a->expr || p[j].a->expr->expr_type != EXPR_VARIABLE)
+	    gfc_internal_error ("check_some_aliasing(): corrupted data");
+
+	  /* Are the expression the same?  */
+	  if (compare_actual_expr (p[i].a->expr, p[j].a->expr) == FAILURE)
+	    break;
+	  f2_intent = p[j].f->sym->attr.intent;
+	  if ((f1_intent == INTENT_IN && f2_intent == INTENT_OUT)
+	      || (f1_intent == INTENT_OUT && f2_intent == INTENT_IN))
+	    {
+	      gfc_warning ("Same actual argument associated with INTENT(%s) "
+			   "argument '%s' and INTENT(%s) argument '%s' at %L",
+			   gfc_intent_string (f1_intent), p[i].f->sym->name,
+			   gfc_intent_string (f2_intent), p[j].f->sym->name,
+			   &p[i].a->expr->where);
+	      t = FAILURE;
+	    }
+	}
+    }
+
+  return t;
+}
+
+
+/* Given formal and actual argument lists that correspond to one
+   another, check that they are compatible in the sense that intents
+   are not mismatched.  */
+
+static gfc_try
+check_intents (gfc_formal_arglist *f, gfc_actual_arglist *a)
+{
+  sym_intent f_intent;
+
+  for (;; f = f->next, a = a->next)
+    {
+      if (f == NULL && a == NULL)
+	break;
+      if (f == NULL || a == NULL)
+	gfc_internal_error ("check_intents(): List mismatch");
+
+      if (a->expr == NULL || a->expr->expr_type != EXPR_VARIABLE)
+	continue;
+
+      f_intent = f->sym->attr.intent;
+
+      if (gfc_pure (NULL) && gfc_impure_variable (a->expr->symtree->n.sym))
+	{
+	  if ((f->sym->ts.type == BT_CLASS && f->sym->attr.class_ok
+	       && CLASS_DATA (f->sym)->attr.class_pointer)
+	      || (f->sym->ts.type != BT_CLASS && f->sym->attr.pointer))
+	    {
+	      gfc_error ("Procedure argument at %L is local to a PURE "
+			 "procedure and has the POINTER attribute",
+			 &a->expr->where);
+	      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->ts.type == BT_CLASS && f->sym->attr.class_ok
+               && CLASS_DATA (f->sym)->attr.class_pointer)
+              || (f->sym->ts.type != BT_CLASS && 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;
+}
+
+
+/* Check how a procedure is used against its interface.  If all goes
+   well, the actual argument list will also end up being properly
+   sorted.  */
+
+gfc_try
+gfc_procedure_use (gfc_symbol *sym, gfc_actual_arglist **ap, locus *where)
+{
+  gfc_formal_arglist *dummy_args;
+
+  /* Warn about calls with an implicit interface.  Special case
+     for calling a ISO_C_BINDING becase c_loc and c_funloc
+     are pseudo-unknown.  Additionally, warn about procedures not
+     explicitly declared at all if requested.  */
+  if (sym->attr.if_source == IFSRC_UNKNOWN && ! sym->attr.is_iso_c)
+    {
+      if (gfc_option.warn_implicit_interface)
+	gfc_warning ("Procedure '%s' called with an implicit interface at %L",
+		     sym->name, where);
+      else if (gfc_option.warn_implicit_procedure
+	       && sym->attr.proc == PROC_UNKNOWN)
+	gfc_warning ("Procedure '%s' called at %L is not explicitly declared",
+		     sym->name, where);
+    }
+
+  if (sym->attr.if_source == IFSRC_UNKNOWN)
+    {
+      gfc_actual_arglist *a;
+
+      if (sym->attr.pointer)
+	{
+	  gfc_error("The pointer object '%s' at %L must have an explicit "
+		    "function interface or be declared as array",
+		    sym->name, where);
+	  return FAILURE;
+	}
+
+      if (sym->attr.allocatable && !sym->attr.external)
+	{
+	  gfc_error("The allocatable object '%s' at %L must have an explicit "
+		    "function interface or be declared as array",
+		    sym->name, where);
+	  return FAILURE;
+	}
+
+      if (sym->attr.allocatable)
+	{
+	  gfc_error("Allocatable function '%s' at %L must have an explicit "
+		    "function interface", sym->name, where);
+	  return FAILURE;
+	}
+
+      for (a = *ap; a; a = a->next)
+	{
+	  /* Skip g77 keyword extensions like %VAL, %REF, %LOC.  */
+	  if (a->name != NULL && a->name[0] != '%')
+	    {
+	      gfc_error("Keyword argument requires explicit interface "
+			"for procedure '%s' at %L", sym->name, &a->expr->where);
+	      break;
+	    }
+
+	  /* TS 29113, 6.2.  */
+	  if (a->expr && a->expr->ts.type == BT_ASSUMED
+	      && sym->intmod_sym_id != ISOCBINDING_LOC)
+	    {
+	      gfc_error ("Assumed-type argument %s at %L requires an explicit "
+			 "interface", a->expr->symtree->n.sym->name,
+			 &a->expr->where);
+	      break;
+	    }
+
+	  /* F2008, C1303 and C1304.  */
+	  if (a->expr
+	      && (a->expr->ts.type == BT_DERIVED || a->expr->ts.type == BT_CLASS)
+	      && ((a->expr->ts.u.derived->from_intmod == INTMOD_ISO_FORTRAN_ENV
+		   && a->expr->ts.u.derived->intmod_sym_id == ISOFORTRAN_LOCK_TYPE)
+		  || gfc_expr_attr (a->expr).lock_comp))
+	    {
+	      gfc_error("Actual argument of LOCK_TYPE or with LOCK_TYPE "
+			"component at %L requires an explicit interface for "
+			"procedure '%s'", &a->expr->where, sym->name);
+	      break;
+	    }
+
+	  if (a->expr && a->expr->expr_type == EXPR_NULL
+	      && a->expr->ts.type == BT_UNKNOWN)
+	    {
+	      gfc_error ("MOLD argument to NULL required at %L", &a->expr->where);
+	      return FAILURE;
+	    }
+
+	  /* TS 29113, C407b.  */
+	  if (a->expr && a->expr->expr_type == EXPR_VARIABLE
+	      && symbol_rank (a->expr->symtree->n.sym) == -1)
+	    {
+	      gfc_error ("Assumed-rank argument requires an explicit interface "
+			 "at %L", &a->expr->where);
+	      return FAILURE;
+	    }
+	}
+
+      return SUCCESS;
+    }
+
+  dummy_args = gfc_sym_get_dummy_args (sym);
+
+  if (!compare_actual_formal (ap, dummy_args, 0, sym->attr.elemental, where))
+    return FAILURE;
+
+  if (check_intents (dummy_args, *ap) == FAILURE)
+    return FAILURE;
+
+  if (gfc_option.warn_aliasing)
+    check_some_aliasing (dummy_args, *ap);
+
+  return SUCCESS;
+}
+
+
+/* Check how a procedure pointer component is used against its interface.
+   If all goes well, the actual argument list will also end up being properly
+   sorted. Completely analogous to gfc_procedure_use.  */
+
+void
+gfc_ppc_use (gfc_component *comp, gfc_actual_arglist **ap, locus *where)
+{
+  /* Warn about calls with an implicit interface.  Special case
+     for calling a ISO_C_BINDING becase c_loc and c_funloc
+     are pseudo-unknown.  */
+  if (gfc_option.warn_implicit_interface
+      && comp->attr.if_source == IFSRC_UNKNOWN
+      && !comp->attr.is_iso_c)
+    gfc_warning ("Procedure pointer component '%s' called with an implicit "
+		 "interface at %L", comp->name, where);
+
+  if (comp->attr.if_source == IFSRC_UNKNOWN)
+    {
+      gfc_actual_arglist *a;
+      for (a = *ap; a; a = a->next)
+	{
+	  /* Skip g77 keyword extensions like %VAL, %REF, %LOC.  */
+	  if (a->name != NULL && a->name[0] != '%')
+	    {
+	      gfc_error("Keyword argument requires explicit interface "
+			"for procedure pointer component '%s' at %L",
+			comp->name, &a->expr->where);
+	      break;
+	    }
+	}
+
+      return;
+    }
+
+  if (!compare_actual_formal (ap, comp->ts.interface->formal, 0,
+			      comp->attr.elemental, where))
+    return;
+
+  check_intents (comp->ts.interface->formal, *ap);
+  if (gfc_option.warn_aliasing)
+    check_some_aliasing (comp->ts.interface->formal, *ap);
+}
+
+
+/* Try if an actual argument list matches the formal list of a symbol,
+   respecting the symbol's attributes like ELEMENTAL.  This is used for
+   GENERIC resolution.  */
+
+bool
+gfc_arglist_matches_symbol (gfc_actual_arglist** args, gfc_symbol* sym)
+{
+  gfc_formal_arglist *dummy_args;
+  bool r;
+
+  gcc_assert (sym->attr.flavor == FL_PROCEDURE);
+
+  dummy_args = gfc_sym_get_dummy_args (sym);
+
+  r = !sym->attr.elemental;
+  if (compare_actual_formal (args, dummy_args, r, !r, NULL))
+    {
+      check_intents (dummy_args, *args);
+      if (gfc_option.warn_aliasing)
+	check_some_aliasing (dummy_args, *args);
+      return true;
+    }
+
+  return false;
+}
+
+
+/* Given an interface pointer and an actual argument list, search for
+   a formal argument list that matches the actual.  If found, returns
+   a pointer to the symbol of the correct interface.  Returns NULL if
+   not found.  */
+
+gfc_symbol *
+gfc_search_interface (gfc_interface *intr, int sub_flag,
+		      gfc_actual_arglist **ap)
+{
+  gfc_symbol *elem_sym = NULL;
+  gfc_symbol *null_sym = NULL;
+  locus null_expr_loc;
+  gfc_actual_arglist *a;
+  bool has_null_arg = false;
+
+  for (a = *ap; a; a = a->next)
+    if (a->expr && a->expr->expr_type == EXPR_NULL
+	&& a->expr->ts.type == BT_UNKNOWN)
+      {
+	has_null_arg = true;
+	null_expr_loc = a->expr->where;
+	break;
+      }
+
+  for (; intr; intr = intr->next)
+    {
+      if (intr->sym->attr.flavor == FL_DERIVED)
+	continue;
+      if (sub_flag && intr->sym->attr.function)
+	continue;
+      if (!sub_flag && intr->sym->attr.subroutine)
+	continue;
+
+      if (gfc_arglist_matches_symbol (ap, intr->sym))
+	{
+	  if (has_null_arg && null_sym)
+	    {
+	      gfc_error ("MOLD= required in NULL() argument at %L: Ambiguity "
+			 "between specific functions %s and %s",
+			 &null_expr_loc, null_sym->name, intr->sym->name);
+	      return NULL;
+	    }
+	  else if (has_null_arg)
+	    {
+	      null_sym = intr->sym;
+	      continue;
+	    }
+
+	  /* Satisfy 12.4.4.1 such that an elemental match has lower
+	     weight than a non-elemental match.  */
+	  if (intr->sym->attr.elemental)
+	    {
+	      elem_sym = intr->sym;
+	      continue;
+	    }
+	  return intr->sym;
+	}
+    }
+
+  if (null_sym)
+    return null_sym;
+
+  return elem_sym ? elem_sym : NULL;
+}
+
+
+/* Do a brute force recursive search for a symbol.  */
+
+static gfc_symtree *
+find_symtree0 (gfc_symtree *root, gfc_symbol *sym)
+{
+  gfc_symtree * st;
+
+  if (root->n.sym == sym)
+    return root;
+
+  st = NULL;
+  if (root->left)
+    st = find_symtree0 (root->left, sym);
+  if (root->right && ! st)
+    st = find_symtree0 (root->right, sym);
+  return st;
+}
+
+
+/* Find a symtree for a symbol.  */
+
+gfc_symtree *
+gfc_find_sym_in_symtree (gfc_symbol *sym)
+{
+  gfc_symtree *st;
+  gfc_namespace *ns;
+
+  /* First try to find it by name.  */
+  gfc_find_sym_tree (sym->name, gfc_current_ns, 1, &st);
+  if (st && st->n.sym == sym)
+    return st;
+
+  /* If it's been renamed, resort to a brute-force search.  */
+  /* TODO: avoid having to do this search.  If the symbol doesn't exist
+     in the symtree for the current namespace, it should probably be added.  */
+  for (ns = gfc_current_ns; ns; ns = ns->parent)
+    {
+      st = find_symtree0 (ns->sym_root, sym);
+      if (st)
+	return st;
+    }
+  gfc_internal_error ("Unable to find symbol %s", sym->name);
+  /* Not reached.  */
+}
+
+
+/* See if the arglist to an operator-call contains a derived-type argument
+   with a matching type-bound operator.  If so, return the matching specific
+   procedure defined as operator-target as well as the base-object to use
+   (which is the found derived-type argument with operator).  The generic
+   name, if any, is transmitted to the final expression via 'gname'.  */
+
+static gfc_typebound_proc*
+matching_typebound_op (gfc_expr** tb_base,
+		       gfc_actual_arglist* args,
+		       gfc_intrinsic_op op, const char* uop,
+		       const char ** gname)
+{
+  gfc_actual_arglist* base;
+
+  for (base = args; base; base = base->next)
+    if (base->expr->ts.type == BT_DERIVED || base->expr->ts.type == BT_CLASS)
+      {
+	gfc_typebound_proc* tb;
+	gfc_symbol* derived;
+	gfc_try result;
+
+	while (base->expr->expr_type == EXPR_OP
+	       && base->expr->value.op.op == INTRINSIC_PARENTHESES)
+	  base->expr = base->expr->value.op.op1;
+
+	if (base->expr->ts.type == BT_CLASS)
+	  {
+	    if (CLASS_DATA (base->expr) == NULL
+		|| !gfc_expr_attr (base->expr).class_ok)
+	      continue;
+	    derived = CLASS_DATA (base->expr)->ts.u.derived;
+	  }
+	else
+	  derived = base->expr->ts.u.derived;
+
+	if (op == INTRINSIC_USER)
+	  {
+	    gfc_symtree* tb_uop;
+
+	    gcc_assert (uop);
+	    tb_uop = gfc_find_typebound_user_op (derived, &result, uop,
+						 false, NULL);
+
+	    if (tb_uop)
+	      tb = tb_uop->n.tb;
+	    else
+	      tb = NULL;
+	  }
+	else
+	  tb = gfc_find_typebound_intrinsic_op (derived, &result, op,
+						false, NULL);
+
+	/* This means we hit a PRIVATE operator which is use-associated and
+	   should thus not be seen.  */
+	if (result == FAILURE)
+	  tb = NULL;
+
+	/* Look through the super-type hierarchy for a matching specific
+	   binding.  */
+	for (; tb; tb = tb->overridden)
+	  {
+	    gfc_tbp_generic* g;
+
+	    gcc_assert (tb->is_generic);
+	    for (g = tb->u.generic; g; g = g->next)
+	      {
+		gfc_symbol* target;
+		gfc_actual_arglist* argcopy;
+		bool matches;
+
+		gcc_assert (g->specific);
+		if (g->specific->error)
+		  continue;
+
+		target = g->specific->u.specific->n.sym;
+
+		/* Check if this arglist matches the formal.  */
+		argcopy = gfc_copy_actual_arglist (args);
+		matches = gfc_arglist_matches_symbol (&argcopy, target);
+		gfc_free_actual_arglist (argcopy);
+
+		/* Return if we found a match.  */
+		if (matches)
+		  {
+		    *tb_base = base->expr;
+		    *gname = g->specific_st->name;
+		    return g->specific;
+		  }
+	      }
+	  }
+      }
+
+  return NULL;
+}
+
+
+/* For the 'actual arglist' of an operator call and a specific typebound
+   procedure that has been found the target of a type-bound operator, build the
+   appropriate EXPR_COMPCALL and resolve it.  We take this indirection over
+   type-bound procedures rather than resolving type-bound operators 'directly'
+   so that we can reuse the existing logic.  */
+
+static void
+build_compcall_for_operator (gfc_expr* e, gfc_actual_arglist* actual,
+			     gfc_expr* base, gfc_typebound_proc* target,
+			     const char *gname)
+{
+  e->expr_type = EXPR_COMPCALL;
+  e->value.compcall.tbp = target;
+  e->value.compcall.name = gname ? gname : "$op";
+  e->value.compcall.actual = actual;
+  e->value.compcall.base_object = base;
+  e->value.compcall.ignore_pass = 1;
+  e->value.compcall.assign = 0;
+  if (e->ts.type == BT_UNKNOWN
+	&& target->function)
+    {
+      if (target->is_generic)
+	e->ts = target->u.generic->specific->u.specific->n.sym->ts;
+      else
+	e->ts = target->u.specific->n.sym->ts;
+    }
+}
+
+
+/* This subroutine is called when an expression is being resolved.
+   The expression node in question is either a user defined operator
+   or an intrinsic operator with arguments that aren't compatible
+   with the operator.  This subroutine builds an actual argument list
+   corresponding to the operands, then searches for a compatible
+   interface.  If one is found, the expression node is replaced with
+   the appropriate function call. We use the 'match' enum to specify
+   whether a replacement has been made or not, or if an error occurred.  */
+
+match
+gfc_extend_expr (gfc_expr *e)
+{
+  gfc_actual_arglist *actual;
+  gfc_symbol *sym;
+  gfc_namespace *ns;
+  gfc_user_op *uop;
+  gfc_intrinsic_op i;
+  const char *gname;
+
+  sym = NULL;
+
+  actual = gfc_get_actual_arglist ();
+  actual->expr = e->value.op.op1;
+
+  gname = NULL;
+
+  if (e->value.op.op2 != NULL)
+    {
+      actual->next = gfc_get_actual_arglist ();
+      actual->next->expr = e->value.op.op2;
+    }
+
+  i = fold_unary_intrinsic (e->value.op.op);
+
+  if (i == INTRINSIC_USER)
+    {
+      for (ns = gfc_current_ns; ns; ns = ns->parent)
+	{
+	  uop = gfc_find_uop (e->value.op.uop->name, ns);
+	  if (uop == NULL)
+	    continue;
+
+	  sym = gfc_search_interface (uop->op, 0, &actual);
+	  if (sym != NULL)
+	    break;
+	}
+    }
+  else
+    {
+      for (ns = gfc_current_ns; ns; ns = ns->parent)
+	{
+	  /* Due to the distinction between '==' and '.eq.' and friends, one has
+	     to check if either is defined.  */
+	  switch (i)
+	    {
+#define CHECK_OS_COMPARISON(comp) \
+  case INTRINSIC_##comp: \
+  case INTRINSIC_##comp##_OS: \
+    sym = gfc_search_interface (ns->op[INTRINSIC_##comp], 0, &actual); \
+    if (!sym) \
+      sym = gfc_search_interface (ns->op[INTRINSIC_##comp##_OS], 0, &actual); \
+    break;
+	      CHECK_OS_COMPARISON(EQ)
+	      CHECK_OS_COMPARISON(NE)
+	      CHECK_OS_COMPARISON(GT)
+	      CHECK_OS_COMPARISON(GE)
+	      CHECK_OS_COMPARISON(LT)
+	      CHECK_OS_COMPARISON(LE)
+#undef CHECK_OS_COMPARISON
+
+	      default:
+		sym = gfc_search_interface (ns->op[i], 0, &actual);
+	    }
+
+	  if (sym != NULL)
+	    break;
+	}
+    }
+
+  /* TODO: Do an ambiguity-check and error if multiple matching interfaces are
+     found rather than just taking the first one and not checking further.  */
+
+  if (sym == NULL)
+    {
+      gfc_typebound_proc* tbo;
+      gfc_expr* tb_base;
+
+      /* See if we find a matching type-bound operator.  */
+      if (i == INTRINSIC_USER)
+	tbo = matching_typebound_op (&tb_base, actual,
+				     i, e->value.op.uop->name, &gname);
+      else
+	switch (i)
+	  {
+#define CHECK_OS_COMPARISON(comp) \
+  case INTRINSIC_##comp: \
+  case INTRINSIC_##comp##_OS: \
+    tbo = matching_typebound_op (&tb_base, actual, \
+				 INTRINSIC_##comp, NULL, &gname); \
+    if (!tbo) \
+      tbo = matching_typebound_op (&tb_base, actual, \
+				   INTRINSIC_##comp##_OS, NULL, &gname); \
+    break;
+	    CHECK_OS_COMPARISON(EQ)
+	    CHECK_OS_COMPARISON(NE)
+	    CHECK_OS_COMPARISON(GT)
+	    CHECK_OS_COMPARISON(GE)
+	    CHECK_OS_COMPARISON(LT)
+	    CHECK_OS_COMPARISON(LE)
+#undef CHECK_OS_COMPARISON
+
+	    default:
+	      tbo = matching_typebound_op (&tb_base, actual, i, NULL, &gname);
+	      break;
+	  }
+
+      /* If there is a matching typebound-operator, replace the expression with
+	 a call to it and succeed.  */
+      if (tbo)
+	{
+	  gfc_try result;
+
+	  gcc_assert (tb_base);
+	  build_compcall_for_operator (e, actual, tb_base, tbo, gname);
+
+	  result = gfc_resolve_expr (e);
+	  if (result == FAILURE)
+	    return MATCH_ERROR;
+
+	  return MATCH_YES;
+	}
+
+      /* Don't use gfc_free_actual_arglist().  */
+      free (actual->next);
+      free (actual);
+
+      return MATCH_NO;
+    }
+
+  /* Change the expression node to a function call.  */
+  e->expr_type = EXPR_FUNCTION;
+  e->symtree = gfc_find_sym_in_symtree (sym);
+  e->value.function.actual = actual;
+  e->value.function.esym = NULL;
+  e->value.function.isym = NULL;
+  e->value.function.name = NULL;
+  e->user_operator = 1;
+
+  if (gfc_resolve_expr (e) == FAILURE)
+    return MATCH_ERROR;
+
+  return MATCH_YES;
+}
+
+
+/* Tries to replace an assignment code node with a subroutine call to
+   the subroutine associated with the assignment operator.  Return
+   SUCCESS if the node was replaced.  On FAILURE, no error is
+   generated.  */
+
+gfc_try
+gfc_extend_assign (gfc_code *c, gfc_namespace *ns)
+{
+  gfc_actual_arglist *actual;
+  gfc_expr *lhs, *rhs;
+  gfc_symbol *sym;
+  const char *gname;
+
+  gname = NULL;
+
+  lhs = c->expr1;
+  rhs = c->expr2;
+
+  /* Don't allow an intrinsic assignment to be replaced.  */
+  if (lhs->ts.type != BT_DERIVED && lhs->ts.type != BT_CLASS
+      && (rhs->rank == 0 || rhs->rank == lhs->rank)
+      && (lhs->ts.type == rhs->ts.type
+	  || (gfc_numeric_ts (&lhs->ts) && gfc_numeric_ts (&rhs->ts))))
+    return FAILURE;
+
+  actual = gfc_get_actual_arglist ();
+  actual->expr = lhs;
+
+  actual->next = gfc_get_actual_arglist ();
+  actual->next->expr = rhs;
+
+  sym = NULL;
+
+  for (; ns; ns = ns->parent)
+    {
+      sym = gfc_search_interface (ns->op[INTRINSIC_ASSIGN], 1, &actual);
+      if (sym != NULL)
+	break;
+    }
+
+  /* TODO: Ambiguity-check, see above for gfc_extend_expr.  */
+
+  if (sym == NULL)
+    {
+      gfc_typebound_proc* tbo;
+      gfc_expr* tb_base;
+
+      /* See if we find a matching type-bound assignment.  */
+      tbo = matching_typebound_op (&tb_base, actual,
+				   INTRINSIC_ASSIGN, NULL, &gname);
+
+      /* If there is one, replace the expression with a call to it and
+	 succeed.  */
+      if (tbo)
+	{
+	  gcc_assert (tb_base);
+	  c->expr1 = gfc_get_expr ();
+	  build_compcall_for_operator (c->expr1, actual, tb_base, tbo, gname);
+	  c->expr1->value.compcall.assign = 1;
+	  c->expr1->where = c->loc;
+	  c->expr2 = NULL;
+	  c->op = EXEC_COMPCALL;
+
+	  /* c is resolved from the caller, so no need to do it here.  */
+
+	  return SUCCESS;
+	}
+
+      free (actual->next);
+      free (actual);
+      return FAILURE;
+    }
+
+  /* Replace the assignment with the call.  */
+  c->op = EXEC_ASSIGN_CALL;
+  c->symtree = gfc_find_sym_in_symtree (sym);
+  c->expr1 = NULL;
+  c->expr2 = NULL;
+  c->ext.actual = actual;
+
+  return SUCCESS;
+}
+
+
+/* Make sure that the interface just parsed is not already present in
+   the given interface list.  Ambiguity isn't checked yet since module
+   procedures can be present without interfaces.  */
+
+gfc_try
+gfc_check_new_interface (gfc_interface *base, gfc_symbol *new_sym, locus loc)
+{
+  gfc_interface *ip;
+
+  for (ip = base; ip; ip = ip->next)
+    {
+      if (ip->sym == new_sym)
+	{
+	  gfc_error ("Entity '%s' at %L is already present in the interface",
+		     new_sym->name, &loc);
+	  return FAILURE;
+	}
+    }
+
+  return SUCCESS;
+}
+
+
+/* Add a symbol to the current interface.  */
+
+gfc_try
+gfc_add_interface (gfc_symbol *new_sym)
+{
+  gfc_interface **head, *intr;
+  gfc_namespace *ns;
+  gfc_symbol *sym;
+
+  switch (current_interface.type)
+    {
+    case INTERFACE_NAMELESS:
+    case INTERFACE_ABSTRACT:
+      return SUCCESS;
+
+    case INTERFACE_INTRINSIC_OP:
+      for (ns = current_interface.ns; ns; ns = ns->parent)
+	switch (current_interface.op)
+	  {
+	    case INTRINSIC_EQ:
+	    case INTRINSIC_EQ_OS:
+	      if (gfc_check_new_interface (ns->op[INTRINSIC_EQ], new_sym,
+					   gfc_current_locus) == FAILURE
+	          || gfc_check_new_interface (ns->op[INTRINSIC_EQ_OS], new_sym,
+					      gfc_current_locus) == FAILURE)
+		return FAILURE;
+	      break;
+
+	    case INTRINSIC_NE:
+	    case INTRINSIC_NE_OS:
+	      if (gfc_check_new_interface (ns->op[INTRINSIC_NE], new_sym,
+					   gfc_current_locus) == FAILURE
+	          || gfc_check_new_interface (ns->op[INTRINSIC_NE_OS], new_sym,
+					      gfc_current_locus) == FAILURE)
+		return FAILURE;
+	      break;
+
+	    case INTRINSIC_GT:
+	    case INTRINSIC_GT_OS:
+	      if (gfc_check_new_interface (ns->op[INTRINSIC_GT], new_sym,
+					   gfc_current_locus) == FAILURE
+	          || gfc_check_new_interface (ns->op[INTRINSIC_GT_OS], new_sym,
+					      gfc_current_locus) == FAILURE)
+		return FAILURE;
+	      break;
+
+	    case INTRINSIC_GE:
+	    case INTRINSIC_GE_OS:
+	      if (gfc_check_new_interface (ns->op[INTRINSIC_GE], new_sym,
+					   gfc_current_locus) == FAILURE
+	          || gfc_check_new_interface (ns->op[INTRINSIC_GE_OS], new_sym,
+					      gfc_current_locus) == FAILURE)
+		return FAILURE;
+	      break;
+
+	    case INTRINSIC_LT:
+	    case INTRINSIC_LT_OS:
+	      if (gfc_check_new_interface (ns->op[INTRINSIC_LT], new_sym,
+					   gfc_current_locus) == FAILURE
+	          || gfc_check_new_interface (ns->op[INTRINSIC_LT_OS], new_sym,
+					      gfc_current_locus) == FAILURE)
+		return FAILURE;
+	      break;
+
+	    case INTRINSIC_LE:
+	    case INTRINSIC_LE_OS:
+	      if (gfc_check_new_interface (ns->op[INTRINSIC_LE], new_sym,
+					   gfc_current_locus) == FAILURE
+	          || gfc_check_new_interface (ns->op[INTRINSIC_LE_OS], new_sym,
+					      gfc_current_locus) == FAILURE)
+		return FAILURE;
+	      break;
+
+	    default:
+	      if (gfc_check_new_interface (ns->op[current_interface.op], new_sym,
+					   gfc_current_locus) == FAILURE)
+		return FAILURE;
+	  }
+
+      head = &current_interface.ns->op[current_interface.op];
+      break;
+
+    case INTERFACE_GENERIC:
+      for (ns = current_interface.ns; ns; ns = ns->parent)
+	{
+	  gfc_find_symbol (current_interface.sym->name, ns, 0, &sym);
+	  if (sym == NULL)
+	    continue;
+
+	  if (gfc_check_new_interface (sym->generic, new_sym, gfc_current_locus)
+	      == FAILURE)
+	    return FAILURE;
+	}
+
+      head = &current_interface.sym->generic;
+      break;
+
+    case INTERFACE_USER_OP:
+      if (gfc_check_new_interface (current_interface.uop->op, new_sym,
+				   gfc_current_locus) == FAILURE)
+	return FAILURE;
+
+      head = &current_interface.uop->op;
+      break;
+
+    default:
+      gfc_internal_error ("gfc_add_interface(): Bad interface type");
+    }
+
+  intr = gfc_get_interface ();
+  intr->sym = new_sym;
+  intr->where = gfc_current_locus;
+
+  intr->next = *head;
+  *head = intr;
+
+  return SUCCESS;
+}
+
+
+gfc_interface *
+gfc_current_interface_head (void)
+{
+  switch (current_interface.type)
+    {
+      case INTERFACE_INTRINSIC_OP:
+	return current_interface.ns->op[current_interface.op];
+	break;
+
+      case INTERFACE_GENERIC:
+	return current_interface.sym->generic;
+	break;
+
+      case INTERFACE_USER_OP:
+	return current_interface.uop->op;
+	break;
+
+      default:
+	gcc_unreachable ();
+    }
+}
+
+
+void
+gfc_set_current_interface_head (gfc_interface *i)
+{
+  switch (current_interface.type)
+    {
+      case INTERFACE_INTRINSIC_OP:
+	current_interface.ns->op[current_interface.op] = i;
+	break;
+
+      case INTERFACE_GENERIC:
+	current_interface.sym->generic = i;
+	break;
+
+      case INTERFACE_USER_OP:
+	current_interface.uop->op = i;
+	break;
+
+      default:
+	gcc_unreachable ();
+    }
+}
+
+
+/* Gets rid of a formal argument list.  We do not free symbols.
+   Symbols are freed when a namespace is freed.  */
+
+void
+gfc_free_formal_arglist (gfc_formal_arglist *p)
+{
+  gfc_formal_arglist *q;
+
+  for (; p; p = q)
+    {
+      q = p->next;
+      free (p);
+    }
+}
+
+
+/* Check that it is ok for the type-bound procedure 'proc' to override the
+   procedure 'old', cf. F08:4.5.7.3.  */
+
+gfc_try
+gfc_check_typebound_override (gfc_symtree* proc, gfc_symtree* old)
+{
+  locus where;
+  gfc_symbol *proc_target, *old_target;
+  unsigned proc_pass_arg, old_pass_arg, argpos;
+  gfc_formal_arglist *proc_formal, *old_formal;
+  bool check_type;
+  char err[200];
+
+  /* This procedure should only be called for non-GENERIC proc.  */
+  gcc_assert (!proc->n.tb->is_generic);
+
+  /* If the overwritten procedure is GENERIC, this is an error.  */
+  if (old->n.tb->is_generic)
+    {
+      gfc_error ("Can't overwrite GENERIC '%s' at %L",
+		 old->name, &proc->n.tb->where);
+      return FAILURE;
+    }
+
+  where = proc->n.tb->where;
+  proc_target = proc->n.tb->u.specific->n.sym;
+  old_target = old->n.tb->u.specific->n.sym;
+
+  /* Check that overridden binding is not NON_OVERRIDABLE.  */
+  if (old->n.tb->non_overridable)
+    {
+      gfc_error ("'%s' at %L overrides a procedure binding declared"
+		 " NON_OVERRIDABLE", proc->name, &where);
+      return FAILURE;
+    }
+
+  /* It's an error to override a non-DEFERRED procedure with a DEFERRED one.  */
+  if (!old->n.tb->deferred && proc->n.tb->deferred)
+    {
+      gfc_error ("'%s' at %L must not be DEFERRED as it overrides a"
+		 " non-DEFERRED binding", proc->name, &where);
+      return FAILURE;
+    }
+
+  /* If the overridden binding is PURE, the overriding must be, too.  */
+  if (old_target->attr.pure && !proc_target->attr.pure)
+    {
+      gfc_error ("'%s' at %L overrides a PURE procedure and must also be PURE",
+		 proc->name, &where);
+      return FAILURE;
+    }
+
+  /* If the overridden binding is ELEMENTAL, the overriding must be, too.  If it
+     is not, the overriding must not be either.  */
+  if (old_target->attr.elemental && !proc_target->attr.elemental)
+    {
+      gfc_error ("'%s' at %L overrides an ELEMENTAL procedure and must also be"
+		 " ELEMENTAL", proc->name, &where);
+      return FAILURE;
+    }
+  if (!old_target->attr.elemental && proc_target->attr.elemental)
+    {
+      gfc_error ("'%s' at %L overrides a non-ELEMENTAL procedure and must not"
+		 " be ELEMENTAL, either", proc->name, &where);
+      return FAILURE;
+    }
+
+  /* If the overridden binding is a SUBROUTINE, the overriding must also be a
+     SUBROUTINE.  */
+  if (old_target->attr.subroutine && !proc_target->attr.subroutine)
+    {
+      gfc_error ("'%s' at %L overrides a SUBROUTINE and must also be a"
+		 " SUBROUTINE", proc->name, &where);
+      return FAILURE;
+    }
+
+  /* If the overridden binding is a FUNCTION, the overriding must also be a
+     FUNCTION and have the same characteristics.  */
+  if (old_target->attr.function)
+    {
+      if (!proc_target->attr.function)
+	{
+	  gfc_error ("'%s' at %L overrides a FUNCTION and must also be a"
+		     " FUNCTION", proc->name, &where);
+	  return FAILURE;
+	}
+
+      if (check_result_characteristics (proc_target, old_target,
+					err, sizeof(err)) == FAILURE)
+	{
+	  gfc_error ("Result mismatch for the overriding procedure "
+		     "'%s' at %L: %s", proc->name, &where, err);
+	  return FAILURE;
+	}
+    }
+
+  /* If the overridden binding is PUBLIC, the overriding one must not be
+     PRIVATE.  */
+  if (old->n.tb->access == ACCESS_PUBLIC
+      && proc->n.tb->access == ACCESS_PRIVATE)
+    {
+      gfc_error ("'%s' at %L overrides a PUBLIC procedure and must not be"
+		 " PRIVATE", proc->name, &where);
+      return FAILURE;
+    }
+
+  /* Compare the formal argument lists of both procedures.  This is also abused
+     to find the position of the passed-object dummy arguments of both
+     bindings as at least the overridden one might not yet be resolved and we
+     need those positions in the check below.  */
+  proc_pass_arg = old_pass_arg = 0;
+  if (!proc->n.tb->nopass && !proc->n.tb->pass_arg)
+    proc_pass_arg = 1;
+  if (!old->n.tb->nopass && !old->n.tb->pass_arg)
+    old_pass_arg = 1;
+  argpos = 1;
+  proc_formal = gfc_sym_get_dummy_args (proc_target);
+  old_formal = gfc_sym_get_dummy_args (old_target);
+  for ( ; proc_formal && old_formal;
+       proc_formal = proc_formal->next, old_formal = old_formal->next)
+    {
+      if (proc->n.tb->pass_arg
+	  && !strcmp (proc->n.tb->pass_arg, proc_formal->sym->name))
+	proc_pass_arg = argpos;
+      if (old->n.tb->pass_arg
+	  && !strcmp (old->n.tb->pass_arg, old_formal->sym->name))
+	old_pass_arg = argpos;
+
+      /* Check that the names correspond.  */
+      if (strcmp (proc_formal->sym->name, old_formal->sym->name))
+	{
+	  gfc_error ("Dummy argument '%s' of '%s' at %L should be named '%s' as"
+		     " to match the corresponding argument of the overridden"
+		     " procedure", proc_formal->sym->name, proc->name, &where,
+		     old_formal->sym->name);
+	  return FAILURE;
+	}
+
+      check_type = proc_pass_arg != argpos && old_pass_arg != argpos;
+      if (check_dummy_characteristics (proc_formal->sym, old_formal->sym,
+				       check_type, err, sizeof(err)) == FAILURE)
+	{
+	  gfc_error ("Argument mismatch for the overriding procedure "
+		     "'%s' at %L: %s", proc->name, &where, err);
+	  return FAILURE;
+	}
+
+      ++argpos;
+    }
+  if (proc_formal || old_formal)
+    {
+      gfc_error ("'%s' at %L must have the same number of formal arguments as"
+		 " the overridden procedure", proc->name, &where);
+      return FAILURE;
+    }
+
+  /* If the overridden binding is NOPASS, the overriding one must also be
+     NOPASS.  */
+  if (old->n.tb->nopass && !proc->n.tb->nopass)
+    {
+      gfc_error ("'%s' at %L overrides a NOPASS binding and must also be"
+		 " NOPASS", proc->name, &where);
+      return FAILURE;
+    }
+
+  /* If the overridden binding is PASS(x), the overriding one must also be
+     PASS and the passed-object dummy arguments must correspond.  */
+  if (!old->n.tb->nopass)
+    {
+      if (proc->n.tb->nopass)
+	{
+	  gfc_error ("'%s' at %L overrides a binding with PASS and must also be"
+		     " PASS", proc->name, &where);
+	  return FAILURE;
+	}
+
+      if (proc_pass_arg != old_pass_arg)
+	{
+	  gfc_error ("Passed-object dummy argument of '%s' at %L must be at"
+		     " the same position as the passed-object dummy argument of"
+		     " the overridden procedure", proc->name, &where);
+	  return FAILURE;
+	}
+    }
+
+  return SUCCESS;
+}