gcc/c-typeck.c

/* Build expressions with type checking for C compiler.
   Copyright (C) 1987, 1988, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
   Free Software Foundation, Inc.

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/>.  */


/* This file is part of the C front end.
   It contains routines to build C expressions given their operands,
   including computing the types of the result, C-specific error checks,
   and some optimization.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "rtl.h"
#include "tree.h"
#include "langhooks.h"
#include "c-tree.h"
#include "tm_p.h"
#include "flags.h"
#include "output.h"
#include "expr.h"
#include "toplev.h"
#include "intl.h"
#include "ggc.h"
#include "target.h"
#include "tree-iterator.h"
#include "gimple.h"
#include "tree-flow.h"

/* Possible cases of implicit bad conversions.  Used to select
   diagnostic messages in convert_for_assignment.  */
enum impl_conv {
  ic_argpass,
  ic_assign,
  ic_init,
  ic_return
};

/* The level of nesting inside "__alignof__".  */
int in_alignof;

/* The level of nesting inside "sizeof".  */
int in_sizeof;

/* The level of nesting inside "typeof".  */
int in_typeof;

struct c_label_context_se *label_context_stack_se;
struct c_label_context_vm *label_context_stack_vm;

/* Nonzero if we've already printed a "missing braces around initializer"
   message within this initializer.  */
static int missing_braces_mentioned;

static int require_constant_value;
static int require_constant_elements;

static bool null_pointer_constant_p (const_tree);
static tree qualify_type (tree, tree);
static int tagged_types_tu_compatible_p (const_tree, const_tree);
static int comp_target_types (tree, tree);
static int function_types_compatible_p (const_tree, const_tree);
static int type_lists_compatible_p (const_tree, const_tree);
static tree decl_constant_value_for_broken_optimization (tree);
static tree lookup_field (tree, tree);
static int convert_arguments (int, tree *, tree, tree, tree, tree);
static tree pointer_diff (tree, tree);
static tree convert_for_assignment (tree, tree, enum impl_conv, tree, tree,
				    int);
static tree valid_compound_expr_initializer (tree, tree);
static void push_string (const char *);
static void push_member_name (tree);
static int spelling_length (void);
static char *print_spelling (char *);
static void warning_init (int, const char *);
static tree digest_init (tree, tree, bool, int);
static void output_init_element (tree, bool, tree, tree, int, bool);
static void output_pending_init_elements (int);
static int set_designator (int);
static void push_range_stack (tree);
static void add_pending_init (tree, tree, bool);
static void set_nonincremental_init (void);
static void set_nonincremental_init_from_string (tree);
static tree find_init_member (tree);
static void readonly_error (tree, enum lvalue_use);
static int lvalue_or_else (const_tree, enum lvalue_use);
static int lvalue_p (const_tree);
static void record_maybe_used_decl (tree);
static int comptypes_internal (const_tree, const_tree);

/* Return true if EXP is a null pointer constant, false otherwise.  */

static bool
null_pointer_constant_p (const_tree expr)
{
  /* This should really operate on c_expr structures, but they aren't
     yet available everywhere required.  */
  tree type = TREE_TYPE (expr);
  return (TREE_CODE (expr) == INTEGER_CST
	  && !TREE_OVERFLOW (expr)
	  && integer_zerop (expr)
	  && (INTEGRAL_TYPE_P (type)
	      || (TREE_CODE (type) == POINTER_TYPE
		  && VOID_TYPE_P (TREE_TYPE (type))
		  && TYPE_QUALS (TREE_TYPE (type)) == TYPE_UNQUALIFIED)));
}
/* This is a cache to hold if two types are compatible or not.  */

struct tagged_tu_seen_cache {
  const struct tagged_tu_seen_cache * next;
  const_tree t1;
  const_tree t2;
  /* The return value of tagged_types_tu_compatible_p if we had seen
     these two types already.  */
  int val;
};

static const struct tagged_tu_seen_cache * tagged_tu_seen_base;
static void free_all_tagged_tu_seen_up_to (const struct tagged_tu_seen_cache *);

/* Do `exp = require_complete_type (exp);' to make sure exp
   does not have an incomplete type.  (That includes void types.)  */

tree
require_complete_type (tree value)
{
  tree type = TREE_TYPE (value);

  if (value == error_mark_node || type == error_mark_node)
    return error_mark_node;

  /* First, detect a valid value with a complete type.  */
  if (COMPLETE_TYPE_P (type))
    return value;

  c_incomplete_type_error (value, type);
  return error_mark_node;
}

/* Print an error message for invalid use of an incomplete type.
   VALUE is the expression that was used (or 0 if that isn't known)
   and TYPE is the type that was invalid.  */

void
c_incomplete_type_error (const_tree value, const_tree type)
{
  const char *type_code_string;

  /* Avoid duplicate error message.  */
  if (TREE_CODE (type) == ERROR_MARK)
    return;

  if (value != 0 && (TREE_CODE (value) == VAR_DECL
		     || TREE_CODE (value) == PARM_DECL))
    error ("%qD has an incomplete type", value);
  else
    {
    retry:
      /* We must print an error message.  Be clever about what it says.  */

      switch (TREE_CODE (type))
	{
	case RECORD_TYPE:
	  type_code_string = "struct";
	  break;

	case UNION_TYPE:
	  type_code_string = "union";
	  break;

	case ENUMERAL_TYPE:
	  type_code_string = "enum";
	  break;

	case VOID_TYPE:
	  error ("invalid use of void expression");
	  return;

	case ARRAY_TYPE:
	  if (TYPE_DOMAIN (type))
	    {
	      if (TYPE_MAX_VALUE (TYPE_DOMAIN (type)) == NULL)
		{
		  error ("invalid use of flexible array member");
		  return;
		}
	      type = TREE_TYPE (type);
	      goto retry;
	    }
	  error ("invalid use of array with unspecified bounds");
	  return;

	default:
	  gcc_unreachable ();
	}

      if (TREE_CODE (TYPE_NAME (type)) == IDENTIFIER_NODE)
	error ("invalid use of undefined type %<%s %E%>",
	       type_code_string, TYPE_NAME (type));
      else
	/* If this type has a typedef-name, the TYPE_NAME is a TYPE_DECL.  */
	error ("invalid use of incomplete typedef %qD", TYPE_NAME (type));
    }
}

/* Given a type, apply default promotions wrt unnamed function
   arguments and return the new type.  */

tree
c_type_promotes_to (tree type)
{
  if (TYPE_MAIN_VARIANT (type) == float_type_node)
    return double_type_node;

  if (c_promoting_integer_type_p (type))
    {
      /* Preserve unsignedness if not really getting any wider.  */
      if (TYPE_UNSIGNED (type)
	  && (TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node)))
	return unsigned_type_node;
      return integer_type_node;
    }

  return type;
}

/* Return a variant of TYPE which has all the type qualifiers of LIKE
   as well as those of TYPE.  */

static tree
qualify_type (tree type, tree like)
{
  return c_build_qualified_type (type,
				 TYPE_QUALS (type) | TYPE_QUALS (like));
}

/* Return true iff the given tree T is a variable length array.  */

bool
c_vla_type_p (const_tree t)
{
  if (TREE_CODE (t) == ARRAY_TYPE
      && C_TYPE_VARIABLE_SIZE (t))
    return true;
  return false;
}

/* Return the composite type of two compatible types.

   We assume that comptypes has already been done and returned
   nonzero; if that isn't so, this may crash.  In particular, we
   assume that qualifiers match.  */

tree
composite_type (tree t1, tree t2)
{
  enum tree_code code1;
  enum tree_code code2;
  tree attributes;

  /* Save time if the two types are the same.  */

  if (t1 == t2) return t1;

  /* If one type is nonsense, use the other.  */
  if (t1 == error_mark_node)
    return t2;
  if (t2 == error_mark_node)
    return t1;

  code1 = TREE_CODE (t1);
  code2 = TREE_CODE (t2);

  /* Merge the attributes.  */
  attributes = targetm.merge_type_attributes (t1, t2);

  /* If one is an enumerated type and the other is the compatible
     integer type, the composite type might be either of the two
     (DR#013 question 3).  For consistency, use the enumerated type as
     the composite type.  */

  if (code1 == ENUMERAL_TYPE && code2 == INTEGER_TYPE)
    return t1;
  if (code2 == ENUMERAL_TYPE && code1 == INTEGER_TYPE)
    return t2;

  gcc_assert (code1 == code2);

  switch (code1)
    {
    case POINTER_TYPE:
      /* For two pointers, do this recursively on the target type.  */
      {
	tree pointed_to_1 = TREE_TYPE (t1);
	tree pointed_to_2 = TREE_TYPE (t2);
	tree target = composite_type (pointed_to_1, pointed_to_2);
	t1 = build_pointer_type (target);
	t1 = build_type_attribute_variant (t1, attributes);
	return qualify_type (t1, t2);
      }

    case ARRAY_TYPE:
      {
	tree elt = composite_type (TREE_TYPE (t1), TREE_TYPE (t2));
	int quals;
	tree unqual_elt;
	tree d1 = TYPE_DOMAIN (t1);
	tree d2 = TYPE_DOMAIN (t2);
	bool d1_variable, d2_variable;
	bool d1_zero, d2_zero;
	bool t1_complete, t2_complete;

	/* We should not have any type quals on arrays at all.  */
	gcc_assert (!TYPE_QUALS (t1) && !TYPE_QUALS (t2));

	t1_complete = COMPLETE_TYPE_P (t1);
	t2_complete = COMPLETE_TYPE_P (t2);

	d1_zero = d1 == 0 || !TYPE_MAX_VALUE (d1);
	d2_zero = d2 == 0 || !TYPE_MAX_VALUE (d2);

	d1_variable = (!d1_zero
		       && (TREE_CODE (TYPE_MIN_VALUE (d1)) != INTEGER_CST
			   || TREE_CODE (TYPE_MAX_VALUE (d1)) != INTEGER_CST));
	d2_variable = (!d2_zero
		       && (TREE_CODE (TYPE_MIN_VALUE (d2)) != INTEGER_CST
			   || TREE_CODE (TYPE_MAX_VALUE (d2)) != INTEGER_CST));
	d1_variable = d1_variable || (d1_zero && c_vla_type_p (t1));
	d2_variable = d2_variable || (d2_zero && c_vla_type_p (t2));

	/* Save space: see if the result is identical to one of the args.  */
	if (elt == TREE_TYPE (t1) && TYPE_DOMAIN (t1)
	    && (d2_variable || d2_zero || !d1_variable))
	  return build_type_attribute_variant (t1, attributes);
	if (elt == TREE_TYPE (t2) && TYPE_DOMAIN (t2)
	    && (d1_variable || d1_zero || !d2_variable))
	  return build_type_attribute_variant (t2, attributes);

	if (elt == TREE_TYPE (t1) && !TYPE_DOMAIN (t2) && !TYPE_DOMAIN (t1))
	  return build_type_attribute_variant (t1, attributes);
	if (elt == TREE_TYPE (t2) && !TYPE_DOMAIN (t2) && !TYPE_DOMAIN (t1))
	  return build_type_attribute_variant (t2, attributes);

	/* Merge the element types, and have a size if either arg has
	   one.  We may have qualifiers on the element types.  To set
	   up TYPE_MAIN_VARIANT correctly, we need to form the
	   composite of the unqualified types and add the qualifiers
	   back at the end.  */
	quals = TYPE_QUALS (strip_array_types (elt));
	unqual_elt = c_build_qualified_type (elt, TYPE_UNQUALIFIED);
	t1 = build_array_type (unqual_elt,
			       TYPE_DOMAIN ((TYPE_DOMAIN (t1)
					     && (d2_variable
						 || d2_zero
						 || !d1_variable))
					    ? t1
					    : t2));
	/* Ensure a composite type involving a zero-length array type
	   is a zero-length type not an incomplete type.  */
	if (d1_zero && d2_zero
	    && (t1_complete || t2_complete)
	    && !COMPLETE_TYPE_P (t1))
	  {
	    TYPE_SIZE (t1) = bitsize_zero_node;
	    TYPE_SIZE_UNIT (t1) = size_zero_node;
	  }
	t1 = c_build_qualified_type (t1, quals);
	return build_type_attribute_variant (t1, attributes);
      }

    case ENUMERAL_TYPE:
    case RECORD_TYPE:
    case UNION_TYPE:
      if (attributes != NULL)
	{
	  /* Try harder not to create a new aggregate type.  */
	  if (attribute_list_equal (TYPE_ATTRIBUTES (t1), attributes))
	    return t1;
	  if (attribute_list_equal (TYPE_ATTRIBUTES (t2), attributes))
	    return t2;
	}
      return build_type_attribute_variant (t1, attributes);

    case FUNCTION_TYPE:
      /* Function types: prefer the one that specified arg types.
	 If both do, merge the arg types.  Also merge the return types.  */
      {
	tree valtype = composite_type (TREE_TYPE (t1), TREE_TYPE (t2));
	tree p1 = TYPE_ARG_TYPES (t1);
	tree p2 = TYPE_ARG_TYPES (t2);
	int len;
	tree newargs, n;
	int i;

	/* Save space: see if the result is identical to one of the args.  */
	if (valtype == TREE_TYPE (t1) && !TYPE_ARG_TYPES (t2))
	  return build_type_attribute_variant (t1, attributes);
	if (valtype == TREE_TYPE (t2) && !TYPE_ARG_TYPES (t1))
	  return build_type_attribute_variant (t2, attributes);

	/* Simple way if one arg fails to specify argument types.  */
	if (TYPE_ARG_TYPES (t1) == 0)
	 {
	    t1 = build_function_type (valtype, TYPE_ARG_TYPES (t2));
	    t1 = build_type_attribute_variant (t1, attributes);
	    return qualify_type (t1, t2);
	 }
	if (TYPE_ARG_TYPES (t2) == 0)
	 {
	   t1 = build_function_type (valtype, TYPE_ARG_TYPES (t1));
	   t1 = build_type_attribute_variant (t1, attributes);
	   return qualify_type (t1, t2);
	 }

	/* If both args specify argument types, we must merge the two
	   lists, argument by argument.  */
	/* Tell global_bindings_p to return false so that variable_size
	   doesn't die on VLAs in parameter types.  */
	c_override_global_bindings_to_false = true;

	len = list_length (p1);
	newargs = 0;

	for (i = 0; i < len; i++)
	  newargs = tree_cons (NULL_TREE, NULL_TREE, newargs);

	n = newargs;

	for (; p1;
	     p1 = TREE_CHAIN (p1), p2 = TREE_CHAIN (p2), n = TREE_CHAIN (n))
	  {
	    /* A null type means arg type is not specified.
	       Take whatever the other function type has.  */
	    if (TREE_VALUE (p1) == 0)
	      {
		TREE_VALUE (n) = TREE_VALUE (p2);
		goto parm_done;
	      }
	    if (TREE_VALUE (p2) == 0)
	      {
		TREE_VALUE (n) = TREE_VALUE (p1);
		goto parm_done;
	      }

	    /* Given  wait (union {union wait *u; int *i} *)
	       and  wait (union wait *),
	       prefer  union wait *  as type of parm.  */
	    if (TREE_CODE (TREE_VALUE (p1)) == UNION_TYPE
		&& TREE_VALUE (p1) != TREE_VALUE (p2))
	      {
		tree memb;
		tree mv2 = TREE_VALUE (p2);
		if (mv2 && mv2 != error_mark_node
		    && TREE_CODE (mv2) != ARRAY_TYPE)
		  mv2 = TYPE_MAIN_VARIANT (mv2);
		for (memb = TYPE_FIELDS (TREE_VALUE (p1));
		     memb; memb = TREE_CHAIN (memb))
		  {
		    tree mv3 = TREE_TYPE (memb);
		    if (mv3 && mv3 != error_mark_node
			&& TREE_CODE (mv3) != ARRAY_TYPE)
		      mv3 = TYPE_MAIN_VARIANT (mv3);
		    if (comptypes (mv3, mv2))
		      {
			TREE_VALUE (n) = composite_type (TREE_TYPE (memb),
							 TREE_VALUE (p2));
			pedwarn (input_location, OPT_pedantic, 
				 "function types not truly compatible in ISO C");
			goto parm_done;
		      }
		  }
	      }
	    if (TREE_CODE (TREE_VALUE (p2)) == UNION_TYPE
		&& TREE_VALUE (p2) != TREE_VALUE (p1))
	      {
		tree memb;
		tree mv1 = TREE_VALUE (p1);
		if (mv1 && mv1 != error_mark_node
		    && TREE_CODE (mv1) != ARRAY_TYPE)
		  mv1 = TYPE_MAIN_VARIANT (mv1);
		for (memb = TYPE_FIELDS (TREE_VALUE (p2));
		     memb; memb = TREE_CHAIN (memb))
		  {
		    tree mv3 = TREE_TYPE (memb);
		    if (mv3 && mv3 != error_mark_node
			&& TREE_CODE (mv3) != ARRAY_TYPE)
		      mv3 = TYPE_MAIN_VARIANT (mv3);
		    if (comptypes (mv3, mv1))
		      {
			TREE_VALUE (n) = composite_type (TREE_TYPE (memb),
							 TREE_VALUE (p1));
			pedwarn (input_location, OPT_pedantic, 
				 "function types not truly compatible in ISO C");
			goto parm_done;
		      }
		  }
	      }
	    TREE_VALUE (n) = composite_type (TREE_VALUE (p1), TREE_VALUE (p2));
	  parm_done: ;
	  }

	c_override_global_bindings_to_false = false;
	t1 = build_function_type (valtype, newargs);
	t1 = qualify_type (t1, t2);
	/* ... falls through ...  */
      }

    default:
      return build_type_attribute_variant (t1, attributes);
    }

}

/* Return the type of a conditional expression between pointers to
   possibly differently qualified versions of compatible types.

   We assume that comp_target_types has already been done and returned
   nonzero; if that isn't so, this may crash.  */

static tree
common_pointer_type (tree t1, tree t2)
{
  tree attributes;
  tree pointed_to_1, mv1;
  tree pointed_to_2, mv2;
  tree target;
  unsigned target_quals;

  /* Save time if the two types are the same.  */

  if (t1 == t2) return t1;

  /* If one type is nonsense, use the other.  */
  if (t1 == error_mark_node)
    return t2;
  if (t2 == error_mark_node)
    return t1;

  gcc_assert (TREE_CODE (t1) == POINTER_TYPE
	      && TREE_CODE (t2) == POINTER_TYPE);

  /* Merge the attributes.  */
  attributes = targetm.merge_type_attributes (t1, t2);

  /* Find the composite type of the target types, and combine the
     qualifiers of the two types' targets.  Do not lose qualifiers on
     array element types by taking the TYPE_MAIN_VARIANT.  */
  mv1 = pointed_to_1 = TREE_TYPE (t1);
  mv2 = pointed_to_2 = TREE_TYPE (t2);
  if (TREE_CODE (mv1) != ARRAY_TYPE)
    mv1 = TYPE_MAIN_VARIANT (pointed_to_1);
  if (TREE_CODE (mv2) != ARRAY_TYPE)
    mv2 = TYPE_MAIN_VARIANT (pointed_to_2);
  target = composite_type (mv1, mv2);

  /* For function types do not merge const qualifiers, but drop them
     if used inconsistently.  The middle-end uses these to mark const
     and noreturn functions.  */
  if (TREE_CODE (pointed_to_1) == FUNCTION_TYPE)
    target_quals = TYPE_QUALS (pointed_to_1) & TYPE_QUALS (pointed_to_2);
  else
    target_quals = TYPE_QUALS (pointed_to_1) | TYPE_QUALS (pointed_to_2);
  t1 = build_pointer_type (c_build_qualified_type (target, target_quals));
  return build_type_attribute_variant (t1, attributes);
}

/* Return the common type for two arithmetic types under the usual
   arithmetic conversions.  The default conversions have already been
   applied, and enumerated types converted to their compatible integer
   types.  The resulting type is unqualified and has no attributes.

   This is the type for the result of most arithmetic operations
   if the operands have the given two types.  */

static tree
c_common_type (tree t1, tree t2)
{
  enum tree_code code1;
  enum tree_code code2;

  /* If one type is nonsense, use the other.  */
  if (t1 == error_mark_node)
    return t2;
  if (t2 == error_mark_node)
    return t1;

  if (TYPE_QUALS (t1) != TYPE_UNQUALIFIED)
    t1 = TYPE_MAIN_VARIANT (t1);

  if (TYPE_QUALS (t2) != TYPE_UNQUALIFIED)
    t2 = TYPE_MAIN_VARIANT (t2);

  if (TYPE_ATTRIBUTES (t1) != NULL_TREE)
    t1 = build_type_attribute_variant (t1, NULL_TREE);

  if (TYPE_ATTRIBUTES (t2) != NULL_TREE)
    t2 = build_type_attribute_variant (t2, NULL_TREE);

  /* Save time if the two types are the same.  */

  if (t1 == t2) return t1;

  code1 = TREE_CODE (t1);
  code2 = TREE_CODE (t2);

  gcc_assert (code1 == VECTOR_TYPE || code1 == COMPLEX_TYPE
	      || code1 == FIXED_POINT_TYPE || code1 == REAL_TYPE
	      || code1 == INTEGER_TYPE);
  gcc_assert (code2 == VECTOR_TYPE || code2 == COMPLEX_TYPE
	      || code2 == FIXED_POINT_TYPE || code2 == REAL_TYPE
	      || code2 == INTEGER_TYPE);

  /* When one operand is a decimal float type, the other operand cannot be
     a generic float type or a complex type.  We also disallow vector types
     here.  */
  if ((DECIMAL_FLOAT_TYPE_P (t1) || DECIMAL_FLOAT_TYPE_P (t2))
      && !(DECIMAL_FLOAT_TYPE_P (t1) && DECIMAL_FLOAT_TYPE_P (t2)))
    {
      if (code1 == VECTOR_TYPE || code2 == VECTOR_TYPE)
	{
	  error ("can%'t mix operands of decimal float and vector types");
	  return error_mark_node;
	}
      if (code1 == COMPLEX_TYPE || code2 == COMPLEX_TYPE)
	{
	  error ("can%'t mix operands of decimal float and complex types");
	  return error_mark_node;
	}
      if (code1 == REAL_TYPE && code2 == REAL_TYPE)
	{
	  error ("can%'t mix operands of decimal float and other float types");
	  return error_mark_node;
	}
    }

  /* If one type is a vector type, return that type.  (How the usual
     arithmetic conversions apply to the vector types extension is not
     precisely specified.)  */
  if (code1 == VECTOR_TYPE)
    return t1;

  if (code2 == VECTOR_TYPE)
    return t2;

  /* If one type is complex, form the common type of the non-complex
     components, then make that complex.  Use T1 or T2 if it is the
     required type.  */
  if (code1 == COMPLEX_TYPE || code2 == COMPLEX_TYPE)
    {
      tree subtype1 = code1 == COMPLEX_TYPE ? TREE_TYPE (t1) : t1;
      tree subtype2 = code2 == COMPLEX_TYPE ? TREE_TYPE (t2) : t2;
      tree subtype = c_common_type (subtype1, subtype2);

      if (code1 == COMPLEX_TYPE && TREE_TYPE (t1) == subtype)
	return t1;
      else if (code2 == COMPLEX_TYPE && TREE_TYPE (t2) == subtype)
	return t2;
      else
	return build_complex_type (subtype);
    }

  /* If only one is real, use it as the result.  */

  if (code1 == REAL_TYPE && code2 != REAL_TYPE)
    return t1;

  if (code2 == REAL_TYPE && code1 != REAL_TYPE)
    return t2;

  /* If both are real and either are decimal floating point types, use
     the decimal floating point type with the greater precision. */

  if (code1 == REAL_TYPE && code2 == REAL_TYPE)
    {
      if (TYPE_MAIN_VARIANT (t1) == dfloat128_type_node
	  || TYPE_MAIN_VARIANT (t2) == dfloat128_type_node)
	return dfloat128_type_node;
      else if (TYPE_MAIN_VARIANT (t1) == dfloat64_type_node
	       || TYPE_MAIN_VARIANT (t2) == dfloat64_type_node)
	return dfloat64_type_node;
      else if (TYPE_MAIN_VARIANT (t1) == dfloat32_type_node
	       || TYPE_MAIN_VARIANT (t2) == dfloat32_type_node)
	return dfloat32_type_node;
    }

  /* Deal with fixed-point types.  */
  if (code1 == FIXED_POINT_TYPE || code2 == FIXED_POINT_TYPE)
    {
      unsigned int unsignedp = 0, satp = 0;
      enum machine_mode m1, m2;
      unsigned int fbit1, ibit1, fbit2, ibit2, max_fbit, max_ibit;

      m1 = TYPE_MODE (t1);
      m2 = TYPE_MODE (t2);

      /* If one input type is saturating, the result type is saturating.  */
      if (TYPE_SATURATING (t1) || TYPE_SATURATING (t2))
	satp = 1;

      /* If both fixed-point types are unsigned, the result type is unsigned.
	 When mixing fixed-point and integer types, follow the sign of the
	 fixed-point type.
	 Otherwise, the result type is signed.  */
      if ((TYPE_UNSIGNED (t1) && TYPE_UNSIGNED (t2)
	   && code1 == FIXED_POINT_TYPE && code2 == FIXED_POINT_TYPE)
	  || (code1 == FIXED_POINT_TYPE && code2 != FIXED_POINT_TYPE
	      && TYPE_UNSIGNED (t1))
	  || (code1 != FIXED_POINT_TYPE && code2 == FIXED_POINT_TYPE
	      && TYPE_UNSIGNED (t2)))
	unsignedp = 1;

      /* The result type is signed.  */
      if (unsignedp == 0)
	{
	  /* If the input type is unsigned, we need to convert to the
	     signed type.  */
	  if (code1 == FIXED_POINT_TYPE && TYPE_UNSIGNED (t1))
	    {
	      enum mode_class mclass = (enum mode_class) 0;
	      if (GET_MODE_CLASS (m1) == MODE_UFRACT)
		mclass = MODE_FRACT;
	      else if (GET_MODE_CLASS (m1) == MODE_UACCUM)
		mclass = MODE_ACCUM;
	      else
		gcc_unreachable ();
	      m1 = mode_for_size (GET_MODE_PRECISION (m1), mclass, 0);
	    }
	  if (code2 == FIXED_POINT_TYPE && TYPE_UNSIGNED (t2))
	    {
	      enum mode_class mclass = (enum mode_class) 0;
	      if (GET_MODE_CLASS (m2) == MODE_UFRACT)
		mclass = MODE_FRACT;
	      else if (GET_MODE_CLASS (m2) == MODE_UACCUM)
		mclass = MODE_ACCUM;
	      else
		gcc_unreachable ();
	      m2 = mode_for_size (GET_MODE_PRECISION (m2), mclass, 0);
	    }
	}

      if (code1 == FIXED_POINT_TYPE)
	{
	  fbit1 = GET_MODE_FBIT (m1);
	  ibit1 = GET_MODE_IBIT (m1);
	}
      else
	{
	  fbit1 = 0;
	  /* Signed integers need to subtract one sign bit.  */
	  ibit1 = TYPE_PRECISION (t1) - (!TYPE_UNSIGNED (t1));
	}

      if (code2 == FIXED_POINT_TYPE)
	{
	  fbit2 = GET_MODE_FBIT (m2);
	  ibit2 = GET_MODE_IBIT (m2);
	}
      else
	{
	  fbit2 = 0;
	  /* Signed integers need to subtract one sign bit.  */
	  ibit2 = TYPE_PRECISION (t2) - (!TYPE_UNSIGNED (t2));
	}

      max_ibit = ibit1 >= ibit2 ?  ibit1 : ibit2;
      max_fbit = fbit1 >= fbit2 ?  fbit1 : fbit2;
      return c_common_fixed_point_type_for_size (max_ibit, max_fbit, unsignedp,
						 satp);
    }

  /* Both real or both integers; use the one with greater precision.  */

  if (TYPE_PRECISION (t1) > TYPE_PRECISION (t2))
    return t1;
  else if (TYPE_PRECISION (t2) > TYPE_PRECISION (t1))
    return t2;

  /* Same precision.  Prefer long longs to longs to ints when the
     same precision, following the C99 rules on integer type rank
     (which are equivalent to the C90 rules for C90 types).  */

  if (TYPE_MAIN_VARIANT (t1) == long_long_unsigned_type_node
      || TYPE_MAIN_VARIANT (t2) == long_long_unsigned_type_node)
    return long_long_unsigned_type_node;

  if (TYPE_MAIN_VARIANT (t1) == long_long_integer_type_node
      || TYPE_MAIN_VARIANT (t2) == long_long_integer_type_node)
    {
      if (TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
	return long_long_unsigned_type_node;
      else
	return long_long_integer_type_node;
    }

  if (TYPE_MAIN_VARIANT (t1) == long_unsigned_type_node
      || TYPE_MAIN_VARIANT (t2) == long_unsigned_type_node)
    return long_unsigned_type_node;

  if (TYPE_MAIN_VARIANT (t1) == long_integer_type_node
      || TYPE_MAIN_VARIANT (t2) == long_integer_type_node)
    {
      /* But preserve unsignedness from the other type,
	 since long cannot hold all the values of an unsigned int.  */
      if (TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
	return long_unsigned_type_node;
      else
	return long_integer_type_node;
    }

  /* Likewise, prefer long double to double even if same size.  */
  if (TYPE_MAIN_VARIANT (t1) == long_double_type_node
      || TYPE_MAIN_VARIANT (t2) == long_double_type_node)
    return long_double_type_node;

  /* Otherwise prefer the unsigned one.  */

  if (TYPE_UNSIGNED (t1))
    return t1;
  else
    return t2;
}

/* Wrapper around c_common_type that is used by c-common.c and other
   front end optimizations that remove promotions.  ENUMERAL_TYPEs
   are allowed here and are converted to their compatible integer types.
   BOOLEAN_TYPEs are allowed here and return either boolean_type_node or
   preferably a non-Boolean type as the common type.  */
tree
common_type (tree t1, tree t2)
{
  if (TREE_CODE (t1) == ENUMERAL_TYPE)
    t1 = c_common_type_for_size (TYPE_PRECISION (t1), 1);
  if (TREE_CODE (t2) == ENUMERAL_TYPE)
    t2 = c_common_type_for_size (TYPE_PRECISION (t2), 1);

  /* If both types are BOOLEAN_TYPE, then return boolean_type_node.  */
  if (TREE_CODE (t1) == BOOLEAN_TYPE
      && TREE_CODE (t2) == BOOLEAN_TYPE)
    return boolean_type_node;

  /* If either type is BOOLEAN_TYPE, then return the other.  */
  if (TREE_CODE (t1) == BOOLEAN_TYPE)
    return t2;
  if (TREE_CODE (t2) == BOOLEAN_TYPE)
    return t1;

  return c_common_type (t1, t2);
}

/* Return 1 if TYPE1 and TYPE2 are compatible types for assignment
   or various other operations.  Return 2 if they are compatible
   but a warning may be needed if you use them together.  */

int
comptypes (tree type1, tree type2)
{
  const struct tagged_tu_seen_cache * tagged_tu_seen_base1 = tagged_tu_seen_base;
  int val;

  val = comptypes_internal (type1, type2);
  free_all_tagged_tu_seen_up_to (tagged_tu_seen_base1);

  return val;
}

/* Return 1 if TYPE1 and TYPE2 are compatible types for assignment
   or various other operations.  Return 2 if they are compatible
   but a warning may be needed if you use them together.  This
   differs from comptypes, in that we don't free the seen types.  */

static int
comptypes_internal (const_tree type1, const_tree type2)
{
  const_tree t1 = type1;
  const_tree t2 = type2;
  int attrval, val;

  /* Suppress errors caused by previously reported errors.  */

  if (t1 == t2 || !t1 || !t2
      || TREE_CODE (t1) == ERROR_MARK || TREE_CODE (t2) == ERROR_MARK)
    return 1;

  /* If either type is the internal version of sizetype, return the
     language version.  */
  if (TREE_CODE (t1) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t1)
      && TYPE_ORIG_SIZE_TYPE (t1))
    t1 = TYPE_ORIG_SIZE_TYPE (t1);

  if (TREE_CODE (t2) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t2)
      && TYPE_ORIG_SIZE_TYPE (t2))
    t2 = TYPE_ORIG_SIZE_TYPE (t2);


  /* Enumerated types are compatible with integer types, but this is
     not transitive: two enumerated types in the same translation unit
     are compatible with each other only if they are the same type.  */

  if (TREE_CODE (t1) == ENUMERAL_TYPE && TREE_CODE (t2) != ENUMERAL_TYPE)
    t1 = c_common_type_for_size (TYPE_PRECISION (t1), TYPE_UNSIGNED (t1));
  else if (TREE_CODE (t2) == ENUMERAL_TYPE && TREE_CODE (t1) != ENUMERAL_TYPE)
    t2 = c_common_type_for_size (TYPE_PRECISION (t2), TYPE_UNSIGNED (t2));

  if (t1 == t2)
    return 1;

  /* Different classes of types can't be compatible.  */

  if (TREE_CODE (t1) != TREE_CODE (t2))
    return 0;

  /* Qualifiers must match. C99 6.7.3p9 */

  if (TYPE_QUALS (t1) != TYPE_QUALS (t2))
    return 0;

  /* Allow for two different type nodes which have essentially the same
     definition.  Note that we already checked for equality of the type
     qualifiers (just above).  */

  if (TREE_CODE (t1) != ARRAY_TYPE
      && TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
    return 1;

  /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
  if (!(attrval = targetm.comp_type_attributes (t1, t2)))
     return 0;

  /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
  val = 0;

  switch (TREE_CODE (t1))
    {
    case POINTER_TYPE:
      /* Do not remove mode or aliasing information.  */
      if (TYPE_MODE (t1) != TYPE_MODE (t2)
	  || TYPE_REF_CAN_ALIAS_ALL (t1) != TYPE_REF_CAN_ALIAS_ALL (t2))
	break;
      val = (TREE_TYPE (t1) == TREE_TYPE (t2)
	     ? 1 : comptypes_internal (TREE_TYPE (t1), TREE_TYPE (t2)));
      break;

    case FUNCTION_TYPE:
      val = function_types_compatible_p (t1, t2);
      break;

    case ARRAY_TYPE:
      {
	tree d1 = TYPE_DOMAIN (t1);
	tree d2 = TYPE_DOMAIN (t2);
	bool d1_variable, d2_variable;
	bool d1_zero, d2_zero;
	val = 1;

	/* Target types must match incl. qualifiers.  */
	if (TREE_TYPE (t1) != TREE_TYPE (t2)
	    && 0 == (val = comptypes_internal (TREE_TYPE (t1), TREE_TYPE (t2))))
	  return 0;

	/* Sizes must match unless one is missing or variable.  */
	if (d1 == 0 || d2 == 0 || d1 == d2)
	  break;

	d1_zero = !TYPE_MAX_VALUE (d1);
	d2_zero = !TYPE_MAX_VALUE (d2);

	d1_variable = (!d1_zero
		       && (TREE_CODE (TYPE_MIN_VALUE (d1)) != INTEGER_CST
			   || TREE_CODE (TYPE_MAX_VALUE (d1)) != INTEGER_CST));
	d2_variable = (!d2_zero
		       && (TREE_CODE (TYPE_MIN_VALUE (d2)) != INTEGER_CST
			   || TREE_CODE (TYPE_MAX_VALUE (d2)) != INTEGER_CST));
	d1_variable = d1_variable || (d1_zero && c_vla_type_p (t1));
	d2_variable = d2_variable || (d2_zero && c_vla_type_p (t2));

	if (d1_variable || d2_variable)
	  break;
	if (d1_zero && d2_zero)
	  break;
	if (d1_zero || d2_zero
	    || !tree_int_cst_equal (TYPE_MIN_VALUE (d1), TYPE_MIN_VALUE (d2))
	    || !tree_int_cst_equal (TYPE_MAX_VALUE (d1), TYPE_MAX_VALUE (d2)))
	  val = 0;

	break;
      }

    case ENUMERAL_TYPE:
    case RECORD_TYPE:
    case UNION_TYPE:
      if (val != 1 && !same_translation_unit_p (t1, t2))
	{
	  tree a1 = TYPE_ATTRIBUTES (t1);
	  tree a2 = TYPE_ATTRIBUTES (t2);

	  if (! attribute_list_contained (a1, a2)
	      && ! attribute_list_contained (a2, a1))
	    break;

	  if (attrval != 2)
	    return tagged_types_tu_compatible_p (t1, t2);
	  val = tagged_types_tu_compatible_p (t1, t2);
	}
      break;

    case VECTOR_TYPE:
      val = TYPE_VECTOR_SUBPARTS (t1) == TYPE_VECTOR_SUBPARTS (t2)
	    && comptypes_internal (TREE_TYPE (t1), TREE_TYPE (t2));
      break;

    default:
      break;
    }
  return attrval == 2 && val == 1 ? 2 : val;
}

/* Return 1 if TTL and TTR are pointers to types that are equivalent,
   ignoring their qualifiers.  */

static int
comp_target_types (tree ttl, tree ttr)
{
  int val;
  tree mvl, mvr;

  /* Do not lose qualifiers on element types of array types that are
     pointer targets by taking their TYPE_MAIN_VARIANT.  */
  mvl = TREE_TYPE (ttl);
  mvr = TREE_TYPE (ttr);
  if (TREE_CODE (mvl) != ARRAY_TYPE)
    mvl = TYPE_MAIN_VARIANT (mvl);
  if (TREE_CODE (mvr) != ARRAY_TYPE)
    mvr = TYPE_MAIN_VARIANT (mvr);
  val = comptypes (mvl, mvr);

  if (val == 2)
    pedwarn (input_location, OPT_pedantic, "types are not quite compatible");
  return val;
}

/* Subroutines of `comptypes'.  */

/* Determine whether two trees derive from the same translation unit.
   If the CONTEXT chain ends in a null, that tree's context is still
   being parsed, so if two trees have context chains ending in null,
   they're in the same translation unit.  */
int
same_translation_unit_p (const_tree t1, const_tree t2)
{
  while (t1 && TREE_CODE (t1) != TRANSLATION_UNIT_DECL)
    switch (TREE_CODE_CLASS (TREE_CODE (t1)))
      {
      case tcc_declaration:
	t1 = DECL_CONTEXT (t1); break;
      case tcc_type:
	t1 = TYPE_CONTEXT (t1); break;
      case tcc_exceptional:
	t1 = BLOCK_SUPERCONTEXT (t1); break;  /* assume block */
      default: gcc_unreachable ();
      }

  while (t2 && TREE_CODE (t2) != TRANSLATION_UNIT_DECL)
    switch (TREE_CODE_CLASS (TREE_CODE (t2)))
      {
      case tcc_declaration:
	t2 = DECL_CONTEXT (t2); break;
      case tcc_type:
	t2 = TYPE_CONTEXT (t2); break;
      case tcc_exceptional:
	t2 = BLOCK_SUPERCONTEXT (t2); break;  /* assume block */
      default: gcc_unreachable ();
      }

  return t1 == t2;
}

/* Allocate the seen two types, assuming that they are compatible. */

static struct tagged_tu_seen_cache *
alloc_tagged_tu_seen_cache (const_tree t1, const_tree t2)
{
  struct tagged_tu_seen_cache *tu = XNEW (struct tagged_tu_seen_cache);
  tu->next = tagged_tu_seen_base;
  tu->t1 = t1;
  tu->t2 = t2;

  tagged_tu_seen_base = tu;

  /* The C standard says that two structures in different translation
     units are compatible with each other only if the types of their
     fields are compatible (among other things).  We assume that they
     are compatible until proven otherwise when building the cache.
     An example where this can occur is:
     struct a
     {
       struct a *next;
     };
     If we are comparing this against a similar struct in another TU,
     and did not assume they were compatible, we end up with an infinite
     loop.  */
  tu->val = 1;
  return tu;
}

/* Free the seen types until we get to TU_TIL. */

static void
free_all_tagged_tu_seen_up_to (const struct tagged_tu_seen_cache *tu_til)
{
  const struct tagged_tu_seen_cache *tu = tagged_tu_seen_base;
  while (tu != tu_til)
    {
      const struct tagged_tu_seen_cache *const tu1
	= (const struct tagged_tu_seen_cache *) tu;
      tu = tu1->next;
      free (CONST_CAST (struct tagged_tu_seen_cache *, tu1));
    }
  tagged_tu_seen_base = tu_til;
}

/* Return 1 if two 'struct', 'union', or 'enum' types T1 and T2 are
   compatible.  If the two types are not the same (which has been
   checked earlier), this can only happen when multiple translation
   units are being compiled.  See C99 6.2.7 paragraph 1 for the exact
   rules.  */

static int
tagged_types_tu_compatible_p (const_tree t1, const_tree t2)
{
  tree s1, s2;
  bool needs_warning = false;

  /* We have to verify that the tags of the types are the same.  This
     is harder than it looks because this may be a typedef, so we have
     to go look at the original type.  It may even be a typedef of a
     typedef...
     In the case of compiler-created builtin structs the TYPE_DECL
     may be a dummy, with no DECL_ORIGINAL_TYPE.  Don't fault.  */
  while (TYPE_NAME (t1)
	 && TREE_CODE (TYPE_NAME (t1)) == TYPE_DECL
	 && DECL_ORIGINAL_TYPE (TYPE_NAME (t1)))
    t1 = DECL_ORIGINAL_TYPE (TYPE_NAME (t1));

  while (TYPE_NAME (t2)
	 && TREE_CODE (TYPE_NAME (t2)) == TYPE_DECL
	 && DECL_ORIGINAL_TYPE (TYPE_NAME (t2)))
    t2 = DECL_ORIGINAL_TYPE (TYPE_NAME (t2));

  /* C90 didn't have the requirement that the two tags be the same.  */
  if (flag_isoc99 && TYPE_NAME (t1) != TYPE_NAME (t2))
    return 0;

  /* C90 didn't say what happened if one or both of the types were
     incomplete; we choose to follow C99 rules here, which is that they
     are compatible.  */
  if (TYPE_SIZE (t1) == NULL
      || TYPE_SIZE (t2) == NULL)
    return 1;

  {
    const struct tagged_tu_seen_cache * tts_i;
    for (tts_i = tagged_tu_seen_base; tts_i != NULL; tts_i = tts_i->next)
      if (tts_i->t1 == t1 && tts_i->t2 == t2)
	return tts_i->val;
  }

  switch (TREE_CODE (t1))
    {
    case ENUMERAL_TYPE:
      {
	struct tagged_tu_seen_cache *tu = alloc_tagged_tu_seen_cache (t1, t2);
	/* Speed up the case where the type values are in the same order.  */
	tree tv1 = TYPE_VALUES (t1);
	tree tv2 = TYPE_VALUES (t2);

	if (tv1 == tv2)
	  {
	    return 1;
	  }

	for (;tv1 && tv2; tv1 = TREE_CHAIN (tv1), tv2 = TREE_CHAIN (tv2))
	  {
	    if (TREE_PURPOSE (tv1) != TREE_PURPOSE (tv2))
	      break;
	    if (simple_cst_equal (TREE_VALUE (tv1), TREE_VALUE (tv2)) != 1)
	      {
		tu->val = 0;
		return 0;
	      }
	  }

	if (tv1 == NULL_TREE && tv2 == NULL_TREE)
	  {
	    return 1;
	  }
	if (tv1 == NULL_TREE || tv2 == NULL_TREE)
	  {
	    tu->val = 0;
	    return 0;
	  }

	if (list_length (TYPE_VALUES (t1)) != list_length (TYPE_VALUES (t2)))
	  {
	    tu->val = 0;
	    return 0;
	  }

	for (s1 = TYPE_VALUES (t1); s1; s1 = TREE_CHAIN (s1))
	  {
	    s2 = purpose_member (TREE_PURPOSE (s1), TYPE_VALUES (t2));
	    if (s2 == NULL
		|| simple_cst_equal (TREE_VALUE (s1), TREE_VALUE (s2)) != 1)
	      {
		tu->val = 0;
		return 0;
	      }
	  }
	return 1;
      }

    case UNION_TYPE:
      {
	struct tagged_tu_seen_cache *tu = alloc_tagged_tu_seen_cache (t1, t2);
	if (list_length (TYPE_FIELDS (t1)) != list_length (TYPE_FIELDS (t2)))
	  {
	    tu->val = 0;
	    return 0;
	  }

	/*  Speed up the common case where the fields are in the same order. */
	for (s1 = TYPE_FIELDS (t1), s2 = TYPE_FIELDS (t2); s1 && s2;
	     s1 = TREE_CHAIN (s1), s2 = TREE_CHAIN (s2))
	  {
	    int result;

	    if (DECL_NAME (s1) != DECL_NAME (s2))
	      break;
	    result = comptypes_internal (TREE_TYPE (s1), TREE_TYPE (s2));

	    if (result != 1 && !DECL_NAME (s1))
	      break;
	    if (result == 0)
	      {
		tu->val = 0;
		return 0;
	      }
	    if (result == 2)
	      needs_warning = true;

	    if (TREE_CODE (s1) == FIELD_DECL
		&& simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
				     DECL_FIELD_BIT_OFFSET (s2)) != 1)
	      {
		tu->val = 0;
		return 0;
	      }
	  }
	if (!s1 && !s2)
	  {
	    tu->val = needs_warning ? 2 : 1;
	    return tu->val;
	  }

	for (s1 = TYPE_FIELDS (t1); s1; s1 = TREE_CHAIN (s1))
	  {
	    bool ok = false;

	    for (s2 = TYPE_FIELDS (t2); s2; s2 = TREE_CHAIN (s2))
	      if (DECL_NAME (s1) == DECL_NAME (s2))
		{
		  int result;

		  result = comptypes_internal (TREE_TYPE (s1), TREE_TYPE (s2));

		  if (result != 1 && !DECL_NAME (s1))
		    continue;
		  if (result == 0)
		    {
		      tu->val = 0;
		      return 0;
		    }
		  if (result == 2)
		    needs_warning = true;

		  if (TREE_CODE (s1) == FIELD_DECL
		      && simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
					   DECL_FIELD_BIT_OFFSET (s2)) != 1)
		    break;

		  ok = true;
		  break;
		}
	    if (!ok)
	      {
		tu->val = 0;
		return 0;
	      }
	  }
	tu->val = needs_warning ? 2 : 10;
	return tu->val;
      }

    case RECORD_TYPE:
      {
	struct tagged_tu_seen_cache *tu = alloc_tagged_tu_seen_cache (t1, t2);

	for (s1 = TYPE_FIELDS (t1), s2 = TYPE_FIELDS (t2);
	     s1 && s2;
	     s1 = TREE_CHAIN (s1), s2 = TREE_CHAIN (s2))
	  {
	    int result;
	    if (TREE_CODE (s1) != TREE_CODE (s2)
		|| DECL_NAME (s1) != DECL_NAME (s2))
	      break;
	    result = comptypes_internal (TREE_TYPE (s1), TREE_TYPE (s2));
	    if (result == 0)
	      break;
	    if (result == 2)
	      needs_warning = true;

	    if (TREE_CODE (s1) == FIELD_DECL
		&& simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
				     DECL_FIELD_BIT_OFFSET (s2)) != 1)
	      break;
	  }
	if (s1 && s2)
	  tu->val = 0;
	else
	  tu->val = needs_warning ? 2 : 1;
	return tu->val;
      }

    default:
      gcc_unreachable ();
    }
}

/* Return 1 if two function types F1 and F2 are compatible.
   If either type specifies no argument types,
   the other must specify a fixed number of self-promoting arg types.
   Otherwise, if one type specifies only the number of arguments,
   the other must specify that number of self-promoting arg types.
   Otherwise, the argument types must match.  */

static int
function_types_compatible_p (const_tree f1, const_tree f2)
{
  tree args1, args2;
  /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
  int val = 1;
  int val1;
  tree ret1, ret2;

  ret1 = TREE_TYPE (f1);
  ret2 = TREE_TYPE (f2);

  /* 'volatile' qualifiers on a function's return type used to mean
     the function is noreturn.  */
  if (TYPE_VOLATILE (ret1) != TYPE_VOLATILE (ret2))
    pedwarn (input_location, 0, "function return types not compatible due to %<volatile%>");
  if (TYPE_VOLATILE (ret1))
    ret1 = build_qualified_type (TYPE_MAIN_VARIANT (ret1),
				 TYPE_QUALS (ret1) & ~TYPE_QUAL_VOLATILE);
  if (TYPE_VOLATILE (ret2))
    ret2 = build_qualified_type (TYPE_MAIN_VARIANT (ret2),
				 TYPE_QUALS (ret2) & ~TYPE_QUAL_VOLATILE);
  val = comptypes_internal (ret1, ret2);
  if (val == 0)
    return 0;

  args1 = TYPE_ARG_TYPES (f1);
  args2 = TYPE_ARG_TYPES (f2);

  /* An unspecified parmlist matches any specified parmlist
     whose argument types don't need default promotions.  */

  if (args1 == 0)
    {
      if (!self_promoting_args_p (args2))
	return 0;
      /* If one of these types comes from a non-prototype fn definition,
	 compare that with the other type's arglist.
	 If they don't match, ask for a warning (but no error).  */
      if (TYPE_ACTUAL_ARG_TYPES (f1)
	  && 1 != type_lists_compatible_p (args2, TYPE_ACTUAL_ARG_TYPES (f1)))
	val = 2;
      return val;
    }
  if (args2 == 0)
    {
      if (!self_promoting_args_p (args1))
	return 0;
      if (TYPE_ACTUAL_ARG_TYPES (f2)
	  && 1 != type_lists_compatible_p (args1, TYPE_ACTUAL_ARG_TYPES (f2)))
	val = 2;
      return val;
    }

  /* Both types have argument lists: compare them and propagate results.  */
  val1 = type_lists_compatible_p (args1, args2);
  return val1 != 1 ? val1 : val;
}

/* Check two lists of types for compatibility,
   returning 0 for incompatible, 1 for compatible,
   or 2 for compatible with warning.  */

static int
type_lists_compatible_p (const_tree args1, const_tree args2)
{
  /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
  int val = 1;
  int newval = 0;

  while (1)
    {
      tree a1, mv1, a2, mv2;
      if (args1 == 0 && args2 == 0)
	return val;
      /* If one list is shorter than the other,
	 they fail to match.  */
      if (args1 == 0 || args2 == 0)
	return 0;
      mv1 = a1 = TREE_VALUE (args1);
      mv2 = a2 = TREE_VALUE (args2);
      if (mv1 && mv1 != error_mark_node && TREE_CODE (mv1) != ARRAY_TYPE)
	mv1 = TYPE_MAIN_VARIANT (mv1);
      if (mv2 && mv2 != error_mark_node && TREE_CODE (mv2) != ARRAY_TYPE)
	mv2 = TYPE_MAIN_VARIANT (mv2);
      /* A null pointer instead of a type
	 means there is supposed to be an argument
	 but nothing is specified about what type it has.
	 So match anything that self-promotes.  */
      if (a1 == 0)
	{
	  if (c_type_promotes_to (a2) != a2)
	    return 0;
	}
      else if (a2 == 0)
	{
	  if (c_type_promotes_to (a1) != a1)
	    return 0;
	}
      /* If one of the lists has an error marker, ignore this arg.  */
      else if (TREE_CODE (a1) == ERROR_MARK
	       || TREE_CODE (a2) == ERROR_MARK)
	;
      else if (!(newval = comptypes_internal (mv1, mv2)))
	{
	  /* Allow  wait (union {union wait *u; int *i} *)
	     and  wait (union wait *)  to be compatible.  */
	  if (TREE_CODE (a1) == UNION_TYPE
	      && (TYPE_NAME (a1) == 0
		  || TYPE_TRANSPARENT_UNION (a1))
	      && TREE_CODE (TYPE_SIZE (a1)) == INTEGER_CST
	      && tree_int_cst_equal (TYPE_SIZE (a1),
				     TYPE_SIZE (a2)))
	    {
	      tree memb;
	      for (memb = TYPE_FIELDS (a1);
		   memb; memb = TREE_CHAIN (memb))
		{
		  tree mv3 = TREE_TYPE (memb);
		  if (mv3 && mv3 != error_mark_node
		      && TREE_CODE (mv3) != ARRAY_TYPE)
		    mv3 = TYPE_MAIN_VARIANT (mv3);
		  if (comptypes_internal (mv3, mv2))
		    break;
		}
	      if (memb == 0)
		return 0;
	    }
	  else if (TREE_CODE (a2) == UNION_TYPE
		   && (TYPE_NAME (a2) == 0
		       || TYPE_TRANSPARENT_UNION (a2))
		   && TREE_CODE (TYPE_SIZE (a2)) == INTEGER_CST
		   && tree_int_cst_equal (TYPE_SIZE (a2),
					  TYPE_SIZE (a1)))
	    {
	      tree memb;
	      for (memb = TYPE_FIELDS (a2);
		   memb; memb = TREE_CHAIN (memb))
		{
		  tree mv3 = TREE_TYPE (memb);
		  if (mv3 && mv3 != error_mark_node
		      && TREE_CODE (mv3) != ARRAY_TYPE)
		    mv3 = TYPE_MAIN_VARIANT (mv3);
		  if (comptypes_internal (mv3, mv1))
		    break;
		}
	      if (memb == 0)
		return 0;
	    }
	  else
	    return 0;
	}

      /* comptypes said ok, but record if it said to warn.  */
      if (newval > val)
	val = newval;

      args1 = TREE_CHAIN (args1);
      args2 = TREE_CHAIN (args2);
    }
}

/* Compute the size to increment a pointer by.  */

static tree
c_size_in_bytes (const_tree type)
{
  enum tree_code code = TREE_CODE (type);

  if (code == FUNCTION_TYPE || code == VOID_TYPE || code == ERROR_MARK)
    return size_one_node;

  if (!COMPLETE_OR_VOID_TYPE_P (type))
    {
      error ("arithmetic on pointer to an incomplete type");
      return size_one_node;
    }

  /* Convert in case a char is more than one unit.  */
  return size_binop (CEIL_DIV_EXPR, TYPE_SIZE_UNIT (type),
		     size_int (TYPE_PRECISION (char_type_node)
			       / BITS_PER_UNIT));
}

/* Return either DECL or its known constant value (if it has one).  */

tree
decl_constant_value (tree decl)
{
  if (/* Don't change a variable array bound or initial value to a constant
	 in a place where a variable is invalid.  Note that DECL_INITIAL
	 isn't valid for a PARM_DECL.  */
      current_function_decl != 0
      && TREE_CODE (decl) != PARM_DECL
      && !TREE_THIS_VOLATILE (decl)
      && TREE_READONLY (decl)
      && DECL_INITIAL (decl) != 0
      && TREE_CODE (DECL_INITIAL (decl)) != ERROR_MARK
      /* This is invalid if initial value is not constant.
	 If it has either a function call, a memory reference,
	 or a variable, then re-evaluating it could give different results.  */
      && TREE_CONSTANT (DECL_INITIAL (decl))
      /* Check for cases where this is sub-optimal, even though valid.  */
      && TREE_CODE (DECL_INITIAL (decl)) != CONSTRUCTOR)
    return DECL_INITIAL (decl);
  return decl;
}

/* Return either DECL or its known constant value (if it has one), but
   return DECL if pedantic or DECL has mode BLKmode.  This is for
   bug-compatibility with the old behavior of decl_constant_value
   (before GCC 3.0); every use of this function is a bug and it should
   be removed before GCC 3.1.  It is not appropriate to use pedantic
   in a way that affects optimization, and BLKmode is probably not the
   right test for avoiding misoptimizations either.  */

static tree
decl_constant_value_for_broken_optimization (tree decl)
{
  tree ret;

  if (pedantic || DECL_MODE (decl) == BLKmode)
    return decl;

  ret = decl_constant_value (decl);
  /* Avoid unwanted tree sharing between the initializer and current
     function's body where the tree can be modified e.g. by the
     gimplifier.  */
  if (ret != decl && TREE_STATIC (decl))
    ret = unshare_expr (ret);
  return ret;
}

/* Convert the array expression EXP to a pointer.  */
static tree
array_to_pointer_conversion (tree exp)
{
  tree orig_exp = exp;
  tree type = TREE_TYPE (exp);
  tree adr;
  tree restype = TREE_TYPE (type);
  tree ptrtype;

  gcc_assert (TREE_CODE (type) == ARRAY_TYPE);

  STRIP_TYPE_NOPS (exp);

  if (TREE_NO_WARNING (orig_exp))
    TREE_NO_WARNING (exp) = 1;

  ptrtype = build_pointer_type (restype);

  if (TREE_CODE (exp) == INDIRECT_REF)
    return convert (ptrtype, TREE_OPERAND (exp, 0));

  if (TREE_CODE (exp) == VAR_DECL)
    {
      /* We are making an ADDR_EXPR of ptrtype.  This is a valid
	 ADDR_EXPR because it's the best way of representing what
	 happens in C when we take the address of an array and place
	 it in a pointer to the element type.  */
      adr = build1 (ADDR_EXPR, ptrtype, exp);
      if (!c_mark_addressable (exp))
	return error_mark_node;
      TREE_SIDE_EFFECTS (adr) = 0;   /* Default would be, same as EXP.  */
      return adr;
    }

  /* This way is better for a COMPONENT_REF since it can
     simplify the offset for a component.  */
  adr = build_unary_op (EXPR_LOCATION (exp), ADDR_EXPR, exp, 1);
  return convert (ptrtype, adr);
}

/* Convert the function expression EXP to a pointer.  */
static tree
function_to_pointer_conversion (tree exp)
{
  tree orig_exp = exp;

  gcc_assert (TREE_CODE (TREE_TYPE (exp)) == FUNCTION_TYPE);

  STRIP_TYPE_NOPS (exp);

  if (TREE_NO_WARNING (orig_exp))
    TREE_NO_WARNING (exp) = 1;

  return build_unary_op (EXPR_LOCATION (exp), ADDR_EXPR, exp, 0);
}

/* Perform the default conversion of arrays and functions to pointers.
   Return the result of converting EXP.  For any other expression, just
   return EXP after removing NOPs.  */

struct c_expr
default_function_array_conversion (struct c_expr exp)
{
  tree orig_exp = exp.value;
  tree type = TREE_TYPE (exp.value);
  enum tree_code code = TREE_CODE (type);

  switch (code)
    {
    case ARRAY_TYPE:
      {
	bool not_lvalue = false;
	bool lvalue_array_p;

	while ((TREE_CODE (exp.value) == NON_LVALUE_EXPR
		|| CONVERT_EXPR_P (exp.value))
	       && TREE_TYPE (TREE_OPERAND (exp.value, 0)) == type)
	  {
	    if (TREE_CODE (exp.value) == NON_LVALUE_EXPR)
	      not_lvalue = true;
	    exp.value = TREE_OPERAND (exp.value, 0);
	  }

	if (TREE_NO_WARNING (orig_exp))
	  TREE_NO_WARNING (exp.value) = 1;

	lvalue_array_p = !not_lvalue && lvalue_p (exp.value);
	if (!flag_isoc99 && !lvalue_array_p)
	  {
	    /* Before C99, non-lvalue arrays do not decay to pointers.
	       Normally, using such an array would be invalid; but it can
	       be used correctly inside sizeof or as a statement expression.
	       Thus, do not give an error here; an error will result later.  */
	    return exp;
	  }

	exp.value = array_to_pointer_conversion (exp.value);
      }
      break;
    case FUNCTION_TYPE:
      exp.value = function_to_pointer_conversion (exp.value);
      break;
    default:
      STRIP_TYPE_NOPS (exp.value);
      if (TREE_NO_WARNING (orig_exp))
	TREE_NO_WARNING (exp.value) = 1;
      break;
    }

  return exp;
}


/* EXP is an expression of integer type.  Apply the integer promotions
   to it and return the promoted value.  */

tree
perform_integral_promotions (tree exp)
{
  tree type = TREE_TYPE (exp);
  enum tree_code code = TREE_CODE (type);

  gcc_assert (INTEGRAL_TYPE_P (type));

  /* Normally convert enums to int,
     but convert wide enums to something wider.  */
  if (code == ENUMERAL_TYPE)
    {
      type = c_common_type_for_size (MAX (TYPE_PRECISION (type),
					  TYPE_PRECISION (integer_type_node)),
				     ((TYPE_PRECISION (type)
				       >= TYPE_PRECISION (integer_type_node))
				      && TYPE_UNSIGNED (type)));

      return convert (type, exp);
    }

  /* ??? This should no longer be needed now bit-fields have their
     proper types.  */
  if (TREE_CODE (exp) == COMPONENT_REF
      && DECL_C_BIT_FIELD (TREE_OPERAND (exp, 1))
      /* If it's thinner than an int, promote it like a
	 c_promoting_integer_type_p, otherwise leave it alone.  */
      && 0 > compare_tree_int (DECL_SIZE (TREE_OPERAND (exp, 1)),
			       TYPE_PRECISION (integer_type_node)))
    return convert (integer_type_node, exp);

  if (c_promoting_integer_type_p (type))
    {
      /* Preserve unsignedness if not really getting any wider.  */
      if (TYPE_UNSIGNED (type)
	  && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
	return convert (unsigned_type_node, exp);

      return convert (integer_type_node, exp);
    }

  return exp;
}


/* Perform default promotions for C data used in expressions.
   Enumeral types or short or char are converted to int.
   In addition, manifest constants symbols are replaced by their values.  */

tree
default_conversion (tree exp)
{
  tree orig_exp;
  tree type = TREE_TYPE (exp);
  enum tree_code code = TREE_CODE (type);

  /* Functions and arrays have been converted during parsing.  */
  gcc_assert (code != FUNCTION_TYPE);
  if (code == ARRAY_TYPE)
    return exp;

  /* Constants can be used directly unless they're not loadable.  */
  if (TREE_CODE (exp) == CONST_DECL)
    exp = DECL_INITIAL (exp);

  /* Replace a nonvolatile const static variable with its value unless
     it is an array, in which case we must be sure that taking the
     address of the array produces consistent results.  */
  else if (optimize && TREE_CODE (exp) == VAR_DECL && code != ARRAY_TYPE)
    {
      exp = decl_constant_value_for_broken_optimization (exp);
      type = TREE_TYPE (exp);
    }

  /* Strip no-op conversions.  */
  orig_exp = exp;
  STRIP_TYPE_NOPS (exp);

  if (TREE_NO_WARNING (orig_exp))
    TREE_NO_WARNING (exp) = 1;

  if (code == VOID_TYPE)
    {
      error ("void value not ignored as it ought to be");
      return error_mark_node;
    }

  exp = require_complete_type (exp);
  if (exp == error_mark_node)
    return error_mark_node;

  if (INTEGRAL_TYPE_P (type))
    return perform_integral_promotions (exp);

  return exp;
}

/* Look up COMPONENT in a structure or union DECL.

   If the component name is not found, returns NULL_TREE.  Otherwise,
   the return value is a TREE_LIST, with each TREE_VALUE a FIELD_DECL
   stepping down the chain to the component, which is in the last
   TREE_VALUE of the list.  Normally the list is of length one, but if
   the component is embedded within (nested) anonymous structures or
   unions, the list steps down the chain to the component.  */

static tree
lookup_field (tree decl, tree component)
{
  tree type = TREE_TYPE (decl);
  tree field;

  /* If TYPE_LANG_SPECIFIC is set, then it is a sorted array of pointers
     to the field elements.  Use a binary search on this array to quickly
     find the element.  Otherwise, do a linear search.  TYPE_LANG_SPECIFIC
     will always be set for structures which have many elements.  */

  if (TYPE_LANG_SPECIFIC (type) && TYPE_LANG_SPECIFIC (type)->s)
    {
      int bot, top, half;
      tree *field_array = &TYPE_LANG_SPECIFIC (type)->s->elts[0];

      field = TYPE_FIELDS (type);
      bot = 0;
      top = TYPE_LANG_SPECIFIC (type)->s->len;
      while (top - bot > 1)
	{
	  half = (top - bot + 1) >> 1;
	  field = field_array[bot+half];

	  if (DECL_NAME (field) == NULL_TREE)
	    {
	      /* Step through all anon unions in linear fashion.  */
	      while (DECL_NAME (field_array[bot]) == NULL_TREE)
		{
		  field = field_array[bot++];
		  if (TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
		      || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
		    {
		      tree anon = lookup_field (field, component);

		      if (anon)
			return tree_cons (NULL_TREE, field, anon);
		    }
		}

	      /* Entire record is only anon unions.  */
	      if (bot > top)
		return NULL_TREE;

	      /* Restart the binary search, with new lower bound.  */
	      continue;
	    }

	  if (DECL_NAME (field) == component)
	    break;
	  if (DECL_NAME (field) < component)
	    bot += half;
	  else
	    top = bot + half;
	}

      if (DECL_NAME (field_array[bot]) == component)
	field = field_array[bot];
      else if (DECL_NAME (field) != component)
	return NULL_TREE;
    }
  else
    {
      for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
	{
	  if (DECL_NAME (field) == NULL_TREE
	      && (TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
		  || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE))
	    {
	      tree anon = lookup_field (field, component);

	      if (anon)
		return tree_cons (NULL_TREE, field, anon);
	    }

	  if (DECL_NAME (field) == component)
	    break;
	}

      if (field == NULL_TREE)
	return NULL_TREE;
    }

  return tree_cons (NULL_TREE, field, NULL_TREE);
}

/* Make an expression to refer to the COMPONENT field of
   structure or union value DATUM.  COMPONENT is an IDENTIFIER_NODE.  */

tree
build_component_ref (tree datum, tree component)
{
  tree type = TREE_TYPE (datum);
  enum tree_code code = TREE_CODE (type);
  tree field = NULL;
  tree ref;

  if (!objc_is_public (datum, component))
    return error_mark_node;

  /* See if there is a field or component with name COMPONENT.  */

  if (code == RECORD_TYPE || code == UNION_TYPE)
    {
      if (!COMPLETE_TYPE_P (type))
	{
	  c_incomplete_type_error (NULL_TREE, type);
	  return error_mark_node;
	}

      field = lookup_field (datum, component);

      if (!field)
	{
	  error ("%qT has no member named %qE", type, component);
	  return error_mark_node;
	}

      /* Chain the COMPONENT_REFs if necessary down to the FIELD.
	 This might be better solved in future the way the C++ front
	 end does it - by giving the anonymous entities each a
	 separate name and type, and then have build_component_ref
	 recursively call itself.  We can't do that here.  */
      do
	{
	  tree subdatum = TREE_VALUE (field);
	  int quals;
	  tree subtype;

	  if (TREE_TYPE (subdatum) == error_mark_node)
	    return error_mark_node;

	  quals = TYPE_QUALS (strip_array_types (TREE_TYPE (subdatum)));
	  quals |= TYPE_QUALS (TREE_TYPE (datum));
	  subtype = c_build_qualified_type (TREE_TYPE (subdatum), quals);

	  ref = build3 (COMPONENT_REF, subtype, datum, subdatum,
			NULL_TREE);
	  if (TREE_READONLY (datum) || TREE_READONLY (subdatum))
	    TREE_READONLY (ref) = 1;
	  if (TREE_THIS_VOLATILE (datum) || TREE_THIS_VOLATILE (subdatum))
	    TREE_THIS_VOLATILE (ref) = 1;

	  if (TREE_DEPRECATED (subdatum))
	    warn_deprecated_use (subdatum);

	  datum = ref;

	  field = TREE_CHAIN (field);
	}
      while (field);

      return ref;
    }
  else if (code != ERROR_MARK)
    error ("request for member %qE in something not a structure or union",
	   component);

  return error_mark_node;
}

/* Given an expression PTR for a pointer, return an expression
   for the value pointed to.
   ERRORSTRING is the name of the operator to appear in error messages.

   LOC is the location to use for the generated tree.  */

tree
build_indirect_ref (location_t loc, tree ptr, const char *errorstring)
{
  tree pointer = default_conversion (ptr);
  tree type = TREE_TYPE (pointer);
  tree ref;

  if (TREE_CODE (type) == POINTER_TYPE)
    {
      if (CONVERT_EXPR_P (pointer)
          || TREE_CODE (pointer) == VIEW_CONVERT_EXPR)
	{
	  /* If a warning is issued, mark it to avoid duplicates from
	     the backend.  This only needs to be done at
	     warn_strict_aliasing > 2.  */
	  if (warn_strict_aliasing > 2)
	    if (strict_aliasing_warning (TREE_TYPE (TREE_OPERAND (pointer, 0)),
					 type, TREE_OPERAND (pointer, 0)))
	      TREE_NO_WARNING (pointer) = 1;
	}

      if (TREE_CODE (pointer) == ADDR_EXPR
	  && (TREE_TYPE (TREE_OPERAND (pointer, 0))
	      == TREE_TYPE (type)))
	{
	  ref = TREE_OPERAND (pointer, 0);
	  protected_set_expr_location (ref, loc);
	  return ref;
	}
      else
	{
	  tree t = TREE_TYPE (type);

	  ref = build1 (INDIRECT_REF, t, pointer);

	  if (!COMPLETE_OR_VOID_TYPE_P (t) && TREE_CODE (t) != ARRAY_TYPE)
	    {
	      error_at (loc, "dereferencing pointer to incomplete type");
	      return error_mark_node;
	    }
	  if (VOID_TYPE_P (t) && skip_evaluation == 0)
	    warning_at (loc, 0, "dereferencing %<void *%> pointer");

	  /* We *must* set TREE_READONLY when dereferencing a pointer to const,
	     so that we get the proper error message if the result is used
	     to assign to.  Also, &* is supposed to be a no-op.
	     And ANSI C seems to specify that the type of the result
	     should be the const type.  */
	  /* A de-reference of a pointer to const is not a const.  It is valid
	     to change it via some other pointer.  */
	  TREE_READONLY (ref) = TYPE_READONLY (t);
	  TREE_SIDE_EFFECTS (ref)
	    = TYPE_VOLATILE (t) || TREE_SIDE_EFFECTS (pointer);
	  TREE_THIS_VOLATILE (ref) = TYPE_VOLATILE (t);
	  protected_set_expr_location (ref, loc);
	  return ref;
	}
    }
  else if (TREE_CODE (pointer) != ERROR_MARK)
    error_at (loc,
	      "invalid type argument of %qs (have %qT)", errorstring, type);
  return error_mark_node;
}

/* This handles expressions of the form "a[i]", which denotes
   an array reference.

   This is logically equivalent in C to *(a+i), but we may do it differently.
   If A is a variable or a member, we generate a primitive ARRAY_REF.
   This avoids forcing the array out of registers, and can work on
   arrays that are not lvalues (for example, members of structures returned
   by functions).

   LOC is the location to use for the returned expression.  */

tree
build_array_ref (tree array, tree index, location_t loc)
{
  tree ret;
  bool swapped = false;
  if (TREE_TYPE (array) == error_mark_node
      || TREE_TYPE (index) == error_mark_node)
    return error_mark_node;

  if (TREE_CODE (TREE_TYPE (array)) != ARRAY_TYPE
      && TREE_CODE (TREE_TYPE (array)) != POINTER_TYPE)
    {
      tree temp;
      if (TREE_CODE (TREE_TYPE (index)) != ARRAY_TYPE
	  && TREE_CODE (TREE_TYPE (index)) != POINTER_TYPE)
	{
	  error_at (loc, "subscripted value is neither array nor pointer");
	  return error_mark_node;
	}
      temp = array;
      array = index;
      index = temp;
      swapped = true;
    }

  if (!INTEGRAL_TYPE_P (TREE_TYPE (index)))
    {
      error_at (loc, "array subscript is not an integer");
      return error_mark_node;
    }

  if (TREE_CODE (TREE_TYPE (TREE_TYPE (array))) == FUNCTION_TYPE)
    {
      error_at (loc, "subscripted value is pointer to function");
      return error_mark_node;
    }

  /* ??? Existing practice has been to warn only when the char
     index is syntactically the index, not for char[array].  */
  if (!swapped)
     warn_array_subscript_with_type_char (index);

  /* Apply default promotions *after* noticing character types.  */
  index = default_conversion (index);

  gcc_assert (TREE_CODE (TREE_TYPE (index)) == INTEGER_TYPE);

  if (TREE_CODE (TREE_TYPE (array)) == ARRAY_TYPE)
    {
      tree rval, type;

      /* An array that is indexed by a non-constant
	 cannot be stored in a register; we must be able to do
	 address arithmetic on its address.
	 Likewise an array of elements of variable size.  */
      if (TREE_CODE (index) != INTEGER_CST
	  || (COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (array)))
	      && TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (array)))) != INTEGER_CST))
	{
	  if (!c_mark_addressable (array))
	    return error_mark_node;
	}
      /* An array that is indexed by a constant value which is not within
	 the array bounds cannot be stored in a register either; because we
	 would get a crash in store_bit_field/extract_bit_field when trying
	 to access a non-existent part of the register.  */
      if (TREE_CODE (index) == INTEGER_CST
	  && TYPE_DOMAIN (TREE_TYPE (array))
	  && !int_fits_type_p (index, TYPE_DOMAIN (TREE_TYPE (array))))
	{
	  if (!c_mark_addressable (array))
	    return error_mark_node;
	}

      if (pedantic)
	{
	  tree foo = array;
	  while (TREE_CODE (foo) == COMPONENT_REF)
	    foo = TREE_OPERAND (foo, 0);
	  if (TREE_CODE (foo) == VAR_DECL && C_DECL_REGISTER (foo))
	    pedwarn (loc, OPT_pedantic, 
		     "ISO C forbids subscripting %<register%> array");
	  else if (!flag_isoc99 && !lvalue_p (foo))
	    pedwarn (loc, OPT_pedantic, 
		     "ISO C90 forbids subscripting non-lvalue array");
	}

      type = TREE_TYPE (TREE_TYPE (array));
      rval = build4 (ARRAY_REF, type, array, index, NULL_TREE, NULL_TREE);
      /* Array ref is const/volatile if the array elements are
	 or if the array is.  */
      TREE_READONLY (rval)
	|= (TYPE_READONLY (TREE_TYPE (TREE_TYPE (array)))
	    | TREE_READONLY (array));
      TREE_SIDE_EFFECTS (rval)
	|= (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (array)))
	    | TREE_SIDE_EFFECTS (array));
      TREE_THIS_VOLATILE (rval)
	|= (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (array)))
	    /* This was added by rms on 16 Nov 91.
	       It fixes  vol struct foo *a;  a->elts[1]
	       in an inline function.
	       Hope it doesn't break something else.  */
	    | TREE_THIS_VOLATILE (array));
      ret = require_complete_type (fold (rval));
      protected_set_expr_location (ret, loc);
      return ret;
    }
  else
    {
      tree ar = default_conversion (array);

      if (ar == error_mark_node)
	return ar;

      gcc_assert (TREE_CODE (TREE_TYPE (ar)) == POINTER_TYPE);
      gcc_assert (TREE_CODE (TREE_TYPE (TREE_TYPE (ar))) != FUNCTION_TYPE);

      return build_indirect_ref
	(loc, build_binary_op (loc, PLUS_EXPR, ar, index, 0),
	 "array indexing");
    }
}

/* Build an external reference to identifier ID.  FUN indicates
   whether this will be used for a function call.  LOC is the source
   location of the identifier.  */
tree
build_external_ref (tree id, int fun, location_t loc)
{
  tree ref;
  tree decl = lookup_name (id);

  /* In Objective-C, an instance variable (ivar) may be preferred to
     whatever lookup_name() found.  */
  decl = objc_lookup_ivar (decl, id);

  if (decl && decl != error_mark_node)
    ref = decl;
  else if (fun)
    /* Implicit function declaration.  */
    ref = implicitly_declare (id);
  else if (decl == error_mark_node)
    /* Don't complain about something that's already been
       complained about.  */
    return error_mark_node;
  else
    {
      undeclared_variable (id, loc);
      return error_mark_node;
    }

  if (TREE_TYPE (ref) == error_mark_node)
    return error_mark_node;

  if (TREE_DEPRECATED (ref))
    warn_deprecated_use (ref);

  /* Recursive call does not count as usage.  */
  if (ref != current_function_decl) 
    {
      TREE_USED (ref) = 1;
    }

  if (TREE_CODE (ref) == FUNCTION_DECL && !in_alignof)
    {
      if (!in_sizeof && !in_typeof)
	C_DECL_USED (ref) = 1;
      else if (DECL_INITIAL (ref) == 0
	       && DECL_EXTERNAL (ref)
	       && !TREE_PUBLIC (ref))
	record_maybe_used_decl (ref);
    }

  if (TREE_CODE (ref) == CONST_DECL)
    {
      used_types_insert (TREE_TYPE (ref));
      ref = DECL_INITIAL (ref);
      TREE_CONSTANT (ref) = 1;
    }
  else if (current_function_decl != 0
	   && !DECL_FILE_SCOPE_P (current_function_decl)
	   && (TREE_CODE (ref) == VAR_DECL
	       || TREE_CODE (ref) == PARM_DECL
	       || TREE_CODE (ref) == FUNCTION_DECL))
    {
      tree context = decl_function_context (ref);

      if (context != 0 && context != current_function_decl)
	DECL_NONLOCAL (ref) = 1;
    }
  /* C99 6.7.4p3: An inline definition of a function with external
     linkage ... shall not contain a reference to an identifier with
     internal linkage.  */
  else if (current_function_decl != 0
	   && DECL_DECLARED_INLINE_P (current_function_decl)
	   && DECL_EXTERNAL (current_function_decl)
	   && VAR_OR_FUNCTION_DECL_P (ref)
	   && (TREE_CODE (ref) != VAR_DECL || TREE_STATIC (ref))
	   && ! TREE_PUBLIC (ref)
	   && DECL_CONTEXT (ref) != current_function_decl)
    pedwarn (loc, 0, "%qD is static but used in inline function %qD "
	     "which is not static", ref, current_function_decl);

  return ref;
}

/* Record details of decls possibly used inside sizeof or typeof.  */
struct maybe_used_decl
{
  /* The decl.  */
  tree decl;
  /* The level seen at (in_sizeof + in_typeof).  */
  int level;
  /* The next one at this level or above, or NULL.  */
  struct maybe_used_decl *next;
};

static struct maybe_used_decl *maybe_used_decls;

/* Record that DECL, an undefined static function reference seen
   inside sizeof or typeof, might be used if the operand of sizeof is
   a VLA type or the operand of typeof is a variably modified
   type.  */

static void
record_maybe_used_decl (tree decl)
{
  struct maybe_used_decl *t = XOBNEW (&parser_obstack, struct maybe_used_decl);
  t->decl = decl;
  t->level = in_sizeof + in_typeof;
  t->next = maybe_used_decls;
  maybe_used_decls = t;
}

/* Pop the stack of decls possibly used inside sizeof or typeof.  If
   USED is false, just discard them.  If it is true, mark them used
   (if no longer inside sizeof or typeof) or move them to the next
   level up (if still inside sizeof or typeof).  */

void
pop_maybe_used (bool used)
{
  struct maybe_used_decl *p = maybe_used_decls;
  int cur_level = in_sizeof + in_typeof;
  while (p && p->level > cur_level)
    {
      if (used)
	{
	  if (cur_level == 0)
	    C_DECL_USED (p->decl) = 1;
	  else
	    p->level = cur_level;
	}
      p = p->next;
    }
  if (!used || cur_level == 0)
    maybe_used_decls = p;
}

/* Return the result of sizeof applied to EXPR.  */

struct c_expr
c_expr_sizeof_expr (struct c_expr expr)
{
  struct c_expr ret;
  if (expr.value == error_mark_node)
    {
      ret.value = error_mark_node;
      ret.original_code = ERROR_MARK;
      pop_maybe_used (false);
    }
  else
    {
      ret.value = c_sizeof (TREE_TYPE (expr.value));
      ret.original_code = ERROR_MARK;
      if (c_vla_type_p (TREE_TYPE (expr.value)))
	{
	  /* sizeof is evaluated when given a vla (C99 6.5.3.4p2).  */
	  ret.value = build2 (COMPOUND_EXPR, TREE_TYPE (ret.value), expr.value, ret.value);
	}
      pop_maybe_used (C_TYPE_VARIABLE_SIZE (TREE_TYPE (expr.value)));
    }
  return ret;
}

/* Return the result of sizeof applied to T, a structure for the type
   name passed to sizeof (rather than the type itself).  */

struct c_expr
c_expr_sizeof_type (struct c_type_name *t)
{
  tree type;
  struct c_expr ret;
  type = groktypename (t);
  ret.value = c_sizeof (type);
  ret.original_code = ERROR_MARK;
  pop_maybe_used (type != error_mark_node
		  ? C_TYPE_VARIABLE_SIZE (type) : false);
  return ret;
}

/* Build a function call to function FUNCTION with parameters PARAMS.
   PARAMS is a list--a chain of TREE_LIST nodes--in which the
   TREE_VALUE of each node is a parameter-expression.
   FUNCTION's data type may be a function type or a pointer-to-function.  */

tree
build_function_call (tree function, tree params)
{
  tree fntype, fundecl = 0;
  tree name = NULL_TREE, result;
  tree tem;
  int nargs;
  tree *argarray;
  

  /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
  STRIP_TYPE_NOPS (function);

  /* Convert anything with function type to a pointer-to-function.  */
  if (TREE_CODE (function) == FUNCTION_DECL)
    {
      /* Implement type-directed function overloading for builtins.
	 resolve_overloaded_builtin and targetm.resolve_overloaded_builtin
	 handle all the type checking.  The result is a complete expression
	 that implements this function call.  */
      tem = resolve_overloaded_builtin (function, params);
      if (tem)
	return tem;

      name = DECL_NAME (function);
      fundecl = function;
    }
  if (TREE_CODE (TREE_TYPE (function)) == FUNCTION_TYPE)
    function = function_to_pointer_conversion (function);

  /* For Objective-C, convert any calls via a cast to OBJC_TYPE_REF
     expressions, like those used for ObjC messenger dispatches.  */
  function = objc_rewrite_function_call (function, params);

  fntype = TREE_TYPE (function);

  if (TREE_CODE (fntype) == ERROR_MARK)
    return error_mark_node;

  if (!(TREE_CODE (fntype) == POINTER_TYPE
	&& TREE_CODE (TREE_TYPE (fntype)) == FUNCTION_TYPE))
    {
      error ("called object %qE is not a function", function);
      return error_mark_node;
    }

  if (fundecl && TREE_THIS_VOLATILE (fundecl))
    current_function_returns_abnormally = 1;

  /* fntype now gets the type of function pointed to.  */
  fntype = TREE_TYPE (fntype);

  /* Convert the parameters to the types declared in the
     function prototype, or apply default promotions.  */

  nargs = list_length (params);
  argarray = (tree *) alloca (nargs * sizeof (tree));
  nargs = convert_arguments (nargs, argarray, TYPE_ARG_TYPES (fntype), 
			     params, function, fundecl);
  if (nargs < 0)
    return error_mark_node;

  /* Check that the function is called through a compatible prototype.
     If it is not, replace the call by a trap, wrapped up in a compound
     expression if necessary.  This has the nice side-effect to prevent
     the tree-inliner from generating invalid assignment trees which may
     blow up in the RTL expander later.  */
  if (CONVERT_EXPR_P (function)
      && TREE_CODE (tem = TREE_OPERAND (function, 0)) == ADDR_EXPR
      && TREE_CODE (tem = TREE_OPERAND (tem, 0)) == FUNCTION_DECL
      && !comptypes (fntype, TREE_TYPE (tem)))
    {
      tree return_type = TREE_TYPE (fntype);
      tree trap = build_function_call (built_in_decls[BUILT_IN_TRAP],
				       NULL_TREE);
      int i;

      /* This situation leads to run-time undefined behavior.  We can't,
	 therefore, simply error unless we can prove that all possible
	 executions of the program must execute the code.  */
      if (warning (0, "function called through a non-compatible type"))
	/* We can, however, treat "undefined" any way we please.
	   Call abort to encourage the user to fix the program.  */
	inform (input_location, "if this code is reached, the program will abort");
      /* Before the abort, allow the function arguments to exit or
	 call longjmp.  */
      for (i = 0; i < nargs; i++)
	trap = build2 (COMPOUND_EXPR, void_type_node, argarray[i], trap);

      if (VOID_TYPE_P (return_type))
	return trap;
      else
	{
	  tree rhs;

	  if (AGGREGATE_TYPE_P (return_type))
	    rhs = build_compound_literal (return_type,
					  build_constructor (return_type, 0));
	  else
	    rhs = fold_convert (return_type, integer_zero_node);

	  return build2 (COMPOUND_EXPR, return_type, trap, rhs);
	}
    }

  /* Check that arguments to builtin functions match the expectations.  */
  if (fundecl
      && DECL_BUILT_IN (fundecl)
      && DECL_BUILT_IN_CLASS (fundecl) == BUILT_IN_NORMAL
      && !check_builtin_function_arguments (fundecl, nargs, argarray))
    return error_mark_node;

  /* Check that the arguments to the function are valid.  */
  check_function_arguments (TYPE_ATTRIBUTES (fntype), nargs, argarray,
			    TYPE_ARG_TYPES (fntype));

  if (require_constant_value)
    {
      result = fold_build_call_array_initializer (TREE_TYPE (fntype),
						  function, nargs, argarray);
      if (TREE_CONSTANT (result)
	  && (name == NULL_TREE
	      || strncmp (IDENTIFIER_POINTER (name), "__builtin_", 10) != 0))
	pedwarn_init (input_location, 0, "initializer element is not constant");
    }
  else
    result = fold_build_call_array (TREE_TYPE (fntype),
				    function, nargs, argarray);

  if (VOID_TYPE_P (TREE_TYPE (result)))
    return result;
  return require_complete_type (result);
}

/* Convert the argument expressions in the list VALUES
   to the types in the list TYPELIST.  The resulting arguments are
   stored in the array ARGARRAY which has size NARGS.

   If TYPELIST is exhausted, or when an element has NULL as its type,
   perform the default conversions.

   PARMLIST is the chain of parm decls for the function being called.
   It may be 0, if that info is not available.
   It is used only for generating error messages.

   FUNCTION is a tree for the called function.  It is used only for
   error messages, where it is formatted with %qE.

   This is also where warnings about wrong number of args are generated.

   VALUES is a chain of TREE_LIST nodes with the elements of the list
   in the TREE_VALUE slots of those nodes.

   Returns the actual number of arguments processed (which may be less
   than NARGS in some error situations), or -1 on failure.  */

static int
convert_arguments (int nargs, tree *argarray,
		   tree typelist, tree values, tree function, tree fundecl)
{
  tree typetail, valtail;
  int parmnum;
  const bool type_generic = fundecl
    && lookup_attribute ("type generic", TYPE_ATTRIBUTES(TREE_TYPE (fundecl)));
  tree selector;

  /* Change pointer to function to the function itself for
     diagnostics.  */
  if (TREE_CODE (function) == ADDR_EXPR
      && TREE_CODE (TREE_OPERAND (function, 0)) == FUNCTION_DECL)
    function = TREE_OPERAND (function, 0);

  /* Handle an ObjC selector specially for diagnostics.  */
  selector = objc_message_selector ();

  /* Scan the given expressions and types, producing individual
     converted arguments and storing them in ARGARRAY.  */

  for (valtail = values, typetail = typelist, parmnum = 0;
       valtail;
       valtail = TREE_CHAIN (valtail), parmnum++)
    {
      tree type = typetail ? TREE_VALUE (typetail) : 0;
      tree val = TREE_VALUE (valtail);
      tree rname = function;
      int argnum = parmnum + 1;
      const char *invalid_func_diag;

      if (type == void_type_node)
	{
	  error ("too many arguments to function %qE", function);
	  return parmnum;
	}

      if (selector && argnum > 2)
	{
	  rname = selector;
	  argnum -= 2;
	}

      STRIP_TYPE_NOPS (val);

      val = require_complete_type (val);

      if (type != 0)
	{
	  /* Formal parm type is specified by a function prototype.  */
	  tree parmval;

	  if (type == error_mark_node || !COMPLETE_TYPE_P (type))
	    {
	      error ("type of formal parameter %d is incomplete", parmnum + 1);
	      parmval = val;
	    }
	  else
	    {
	      /* Optionally warn about conversions that
		 differ from the default conversions.  */
	      if (warn_traditional_conversion || warn_traditional)
		{
		  unsigned int formal_prec = TYPE_PRECISION (type);

		  if (INTEGRAL_TYPE_P (type)
		      && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
		    warning (0, "passing argument %d of %qE as integer "
			     "rather than floating due to prototype",
			     argnum, rname);
		  if (INTEGRAL_TYPE_P (type)
		      && TREE_CODE (TREE_TYPE (val)) == COMPLEX_TYPE)
		    warning (0, "passing argument %d of %qE as integer "
			     "rather than complex due to prototype",
			     argnum, rname);
		  else if (TREE_CODE (type) == COMPLEX_TYPE
			   && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
		    warning (0, "passing argument %d of %qE as complex "
			     "rather than floating due to prototype",
			     argnum, rname);
		  else if (TREE_CODE (type) == REAL_TYPE
			   && INTEGRAL_TYPE_P (TREE_TYPE (val)))
		    warning (0, "passing argument %d of %qE as floating "
			     "rather than integer due to prototype",
			     argnum, rname);
		  else if (TREE_CODE (type) == COMPLEX_TYPE
			   && INTEGRAL_TYPE_P (TREE_TYPE (val)))
		    warning (0, "passing argument %d of %qE as complex "
			     "rather than integer due to prototype",
			     argnum, rname);
		  else if (TREE_CODE (type) == REAL_TYPE
			   && TREE_CODE (TREE_TYPE (val)) == COMPLEX_TYPE)
		    warning (0, "passing argument %d of %qE as floating "
			     "rather than complex due to prototype",
			     argnum, rname);
		  /* ??? At some point, messages should be written about
		     conversions between complex types, but that's too messy
		     to do now.  */
		  else if (TREE_CODE (type) == REAL_TYPE
			   && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
		    {
		      /* Warn if any argument is passed as `float',
			 since without a prototype it would be `double'.  */
		      if (formal_prec == TYPE_PRECISION (float_type_node)
			  && type != dfloat32_type_node)
			warning (0, "passing argument %d of %qE as %<float%> "
				 "rather than %<double%> due to prototype",
				 argnum, rname);

		      /* Warn if mismatch between argument and prototype
			 for decimal float types.  Warn of conversions with
			 binary float types and of precision narrowing due to
			 prototype. */
 		      else if (type != TREE_TYPE (val)
			       && (type == dfloat32_type_node
				   || type == dfloat64_type_node
				   || type == dfloat128_type_node
				   || TREE_TYPE (val) == dfloat32_type_node
				   || TREE_TYPE (val) == dfloat64_type_node
				   || TREE_TYPE (val) == dfloat128_type_node)
			       && (formal_prec
				   <= TYPE_PRECISION (TREE_TYPE (val))
				   || (type == dfloat128_type_node
				       && (TREE_TYPE (val)
					   != dfloat64_type_node
					   && (TREE_TYPE (val)
					       != dfloat32_type_node)))
				   || (type == dfloat64_type_node
				       && (TREE_TYPE (val)
					   != dfloat32_type_node))))
			warning (0, "passing argument %d of %qE as %qT "
				 "rather than %qT due to prototype",
				 argnum, rname, type, TREE_TYPE (val));

		    }
		  /* Detect integer changing in width or signedness.
		     These warnings are only activated with
		     -Wtraditional-conversion, not with -Wtraditional.  */
		  else if (warn_traditional_conversion && INTEGRAL_TYPE_P (type)
			   && INTEGRAL_TYPE_P (TREE_TYPE (val)))
		    {
		      tree would_have_been = default_conversion (val);
		      tree type1 = TREE_TYPE (would_have_been);

		      if (TREE_CODE (type) == ENUMERAL_TYPE
			  && (TYPE_MAIN_VARIANT (type)
			      == TYPE_MAIN_VARIANT (TREE_TYPE (val))))
			/* No warning if function asks for enum
			   and the actual arg is that enum type.  */
			;
		      else if (formal_prec != TYPE_PRECISION (type1))
			warning (OPT_Wtraditional_conversion, "passing argument %d of %qE "
				 "with different width due to prototype",
				 argnum, rname);
		      else if (TYPE_UNSIGNED (type) == TYPE_UNSIGNED (type1))
			;
		      /* Don't complain if the formal parameter type
			 is an enum, because we can't tell now whether
			 the value was an enum--even the same enum.  */
		      else if (TREE_CODE (type) == ENUMERAL_TYPE)
			;
		      else if (TREE_CODE (val) == INTEGER_CST
			       && int_fits_type_p (val, type))
			/* Change in signedness doesn't matter
			   if a constant value is unaffected.  */
			;
		      /* If the value is extended from a narrower
			 unsigned type, it doesn't matter whether we
			 pass it as signed or unsigned; the value
			 certainly is the same either way.  */
		      else if (TYPE_PRECISION (TREE_TYPE (val)) < TYPE_PRECISION (type)
			       && TYPE_UNSIGNED (TREE_TYPE (val)))
			;
		      else if (TYPE_UNSIGNED (type))
			warning (OPT_Wtraditional_conversion, "passing argument %d of %qE "
				 "as unsigned due to prototype",
				 argnum, rname);
		      else
			warning (OPT_Wtraditional_conversion, "passing argument %d of %qE "
				 "as signed due to prototype", argnum, rname);
		    }
		}

	      parmval = convert_for_assignment (type, val, ic_argpass,
						fundecl, function,
						parmnum + 1);

	      if (targetm.calls.promote_prototypes (fundecl ? TREE_TYPE (fundecl) : 0)
		  && INTEGRAL_TYPE_P (type)
		  && (TYPE_PRECISION (type) < TYPE_PRECISION (integer_type_node)))
		parmval = default_conversion (parmval);
	    }
	  argarray[parmnum] = parmval;
	}
      else if (TREE_CODE (TREE_TYPE (val)) == REAL_TYPE
	       && (TYPE_PRECISION (TREE_TYPE (val))
		   < TYPE_PRECISION (double_type_node))
	       && !DECIMAL_FLOAT_MODE_P (TYPE_MODE (TREE_TYPE (val))))
        {
	  if (type_generic)
	    argarray[parmnum] = val;
	  else
	    /* Convert `float' to `double'.  */
	    argarray[parmnum] = convert (double_type_node, val);
	}
      else if ((invalid_func_diag =
		targetm.calls.invalid_arg_for_unprototyped_fn (typelist, fundecl, val)))
	{
	  error (invalid_func_diag);
	  return -1;
	}
      else
	/* Convert `short' and `char' to full-size `int'.  */
	argarray[parmnum] = default_conversion (val);

      if (typetail)
	typetail = TREE_CHAIN (typetail);
    }

  gcc_assert (parmnum == nargs);

  if (typetail != 0 && TREE_VALUE (typetail) != void_type_node)
    {
      error ("too few arguments to function %qE", function);
      return -1;
    }

  return parmnum;
}

/* This is the entry point used by the parser to build unary operators
   in the input.  CODE, a tree_code, specifies the unary operator, and
   ARG is the operand.  For unary plus, the C parser currently uses
   CONVERT_EXPR for code.

   LOC is the location to use for the tree generated.
*/

struct c_expr
parser_build_unary_op (enum tree_code code, struct c_expr arg, location_t loc)
{
  struct c_expr result;

  result.value = build_unary_op (loc, code, arg.value, 0);
  result.original_code = code;
  
  if (TREE_OVERFLOW_P (result.value) && !TREE_OVERFLOW_P (arg.value))
    overflow_warning (result.value);

  return result;
}

/* This is the entry point used by the parser to build binary operators
   in the input.  CODE, a tree_code, specifies the binary operator, and
   ARG1 and ARG2 are the operands.  In addition to constructing the
   expression, we check for operands that were written with other binary
   operators in a way that is likely to confuse the user.

   LOCATION is the location of the binary operator.  */

struct c_expr
parser_build_binary_op (location_t location, enum tree_code code,
			struct c_expr arg1, struct c_expr arg2)
{
  struct c_expr result;

  enum tree_code code1 = arg1.original_code;
  enum tree_code code2 = arg2.original_code;

  result.value = build_binary_op (location, code,
				  arg1.value, arg2.value, 1);
  result.original_code = code;

  if (TREE_CODE (result.value) == ERROR_MARK)
    return result;

  if (location != UNKNOWN_LOCATION)
    protected_set_expr_location (result.value, location);

  /* Check for cases such as x+y<<z which users are likely
     to misinterpret.  */
  if (warn_parentheses)
    warn_about_parentheses (code, code1, arg1.value, code2, arg2.value);

  if (TREE_CODE_CLASS (code1) != tcc_comparison)
    warn_logical_operator (code, arg1.value, arg2.value);

  /* Warn about comparisons against string literals, with the exception
     of testing for equality or inequality of a string literal with NULL.  */
  if (code == EQ_EXPR || code == NE_EXPR)
    {
      if ((code1 == STRING_CST && !integer_zerop (arg2.value))
	  || (code2 == STRING_CST && !integer_zerop (arg1.value)))
	warning (OPT_Waddress, "comparison with string literal results in unspecified behavior");
    }
  else if (TREE_CODE_CLASS (code) == tcc_comparison
	   && (code1 == STRING_CST || code2 == STRING_CST))
    warning (OPT_Waddress, "comparison with string literal results in unspecified behavior");

  if (TREE_OVERFLOW_P (result.value) 
      && !TREE_OVERFLOW_P (arg1.value) 
      && !TREE_OVERFLOW_P (arg2.value))
    overflow_warning (result.value);

  return result;
}

/* Return a tree for the difference of pointers OP0 and OP1.
   The resulting tree has type int.  */

static tree
pointer_diff (tree op0, tree op1)
{
  tree restype = ptrdiff_type_node;

  tree target_type = TREE_TYPE (TREE_TYPE (op0));
  tree con0, con1, lit0, lit1;
  tree orig_op1 = op1;

  if (TREE_CODE (target_type) == VOID_TYPE)
    pedwarn (input_location, pedantic ? OPT_pedantic : OPT_Wpointer_arith, 
	     "pointer of type %<void *%> used in subtraction");
  if (TREE_CODE (target_type) == FUNCTION_TYPE)
    pedwarn (input_location, pedantic ? OPT_pedantic : OPT_Wpointer_arith, 
	     "pointer to a function used in subtraction");

  /* If the conversion to ptrdiff_type does anything like widening or
     converting a partial to an integral mode, we get a convert_expression
     that is in the way to do any simplifications.
     (fold-const.c doesn't know that the extra bits won't be needed.
     split_tree uses STRIP_SIGN_NOPS, which leaves conversions to a
     different mode in place.)
     So first try to find a common term here 'by hand'; we want to cover
     at least the cases that occur in legal static initializers.  */
  if (CONVERT_EXPR_P (op0)
      && (TYPE_PRECISION (TREE_TYPE (op0))
	  == TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (op0, 0)))))
    con0 = TREE_OPERAND (op0, 0);
  else
    con0 = op0;
  if (CONVERT_EXPR_P (op1)
      && (TYPE_PRECISION (TREE_TYPE (op1))
	  == TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (op1, 0)))))
    con1 = TREE_OPERAND (op1, 0);
  else
    con1 = op1;

  if (TREE_CODE (con0) == PLUS_EXPR)
    {
      lit0 = TREE_OPERAND (con0, 1);
      con0 = TREE_OPERAND (con0, 0);
    }
  else
    lit0 = integer_zero_node;

  if (TREE_CODE (con1) == PLUS_EXPR)
    {
      lit1 = TREE_OPERAND (con1, 1);
      con1 = TREE_OPERAND (con1, 0);
    }
  else
    lit1 = integer_zero_node;

  if (operand_equal_p (con0, con1, 0))
    {
      op0 = lit0;
      op1 = lit1;
    }


  /* First do the subtraction as integers;
     then drop through to build the divide operator.
     Do not do default conversions on the minus operator
     in case restype is a short type.  */

  op0 = build_binary_op (input_location,
			 MINUS_EXPR, convert (restype, op0),
			 convert (restype, op1), 0);
  /* This generates an error if op1 is pointer to incomplete type.  */
  if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (TREE_TYPE (orig_op1))))
    error ("arithmetic on pointer to an incomplete type");

  /* This generates an error if op0 is pointer to incomplete type.  */
  op1 = c_size_in_bytes (target_type);

  /* Divide by the size, in easiest possible way.  */
  return fold_build2 (EXACT_DIV_EXPR, restype, op0, convert (restype, op1));
}

/* Construct and perhaps optimize a tree representation
   for a unary operation.  CODE, a tree_code, specifies the operation
   and XARG is the operand.
   For any CODE other than ADDR_EXPR, FLAG nonzero suppresses
   the default promotions (such as from short to int).
   For ADDR_EXPR, the default promotions are not applied; FLAG nonzero
   allows non-lvalues; this is only used to handle conversion of non-lvalue
   arrays to pointers in C99.

   LOCATION is the location of the operator.  */

tree
build_unary_op (location_t location,
		enum tree_code code, tree xarg, int flag)
{
  /* No default_conversion here.  It causes trouble for ADDR_EXPR.  */
  tree arg = xarg;
  tree argtype = 0;
  enum tree_code typecode;
  tree val;
  tree ret = error_mark_node;
  int noconvert = flag;
  const char *invalid_op_diag;

  if (code != ADDR_EXPR)
    arg = require_complete_type (arg);

  typecode = TREE_CODE (TREE_TYPE (arg));
  if (typecode == ERROR_MARK)
    return error_mark_node;
  if (typecode == ENUMERAL_TYPE || typecode == BOOLEAN_TYPE)
    typecode = INTEGER_TYPE;

  if ((invalid_op_diag
       = targetm.invalid_unary_op (code, TREE_TYPE (xarg))))
    {
      error_at (location, invalid_op_diag);
      return error_mark_node;
    }

  switch (code)
    {
    case CONVERT_EXPR:
      /* This is used for unary plus, because a CONVERT_EXPR
	 is enough to prevent anybody from looking inside for
	 associativity, but won't generate any code.  */
      if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
	    || typecode == FIXED_POINT_TYPE || typecode == COMPLEX_TYPE
	    || typecode == VECTOR_TYPE))
	{
	  error_at (location, "wrong type argument to unary plus");
	  return error_mark_node;
	}
      else if (!noconvert)
	arg = default_conversion (arg);
      arg = non_lvalue (arg);
      break;

    case NEGATE_EXPR:
      if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
	    || typecode == FIXED_POINT_TYPE || typecode == COMPLEX_TYPE
	    || typecode == VECTOR_TYPE))
	{
	  error_at (location, "wrong type argument to unary minus");
	  return error_mark_node;
	}
      else if (!noconvert)
	arg = default_conversion (arg);
      break;

    case BIT_NOT_EXPR:
      /* ~ works on integer types and non float vectors. */
      if (typecode == INTEGER_TYPE
	  || (typecode == VECTOR_TYPE
	      && !VECTOR_FLOAT_TYPE_P (TREE_TYPE (arg))))
	{
	  if (!noconvert)
	    arg = default_conversion (arg);
	}
      else if (typecode == COMPLEX_TYPE)
	{
	  code = CONJ_EXPR;
	  pedwarn (location, OPT_pedantic, 
		   "ISO C does not support %<~%> for complex conjugation");
	  if (!noconvert)
	    arg = default_conversion (arg);
	}
      else
	{
	  error_at (location, "wrong type argument to bit-complement");
	  return error_mark_node;
	}
      break;

    case ABS_EXPR:
      if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE))
	{
	  error_at (location, "wrong type argument to abs");
	  return error_mark_node;
	}
      else if (!noconvert)
	arg = default_conversion (arg);
      break;

    case CONJ_EXPR:
      /* Conjugating a real value is a no-op, but allow it anyway.  */
      if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
	    || typecode == COMPLEX_TYPE))
	{
	  error_at (location, "wrong type argument to conjugation");
	  return error_mark_node;
	}
      else if (!noconvert)
	arg = default_conversion (arg);
      break;

    case TRUTH_NOT_EXPR:
      if (typecode != INTEGER_TYPE && typecode != FIXED_POINT_TYPE
	  && typecode != REAL_TYPE && typecode != POINTER_TYPE
	  && typecode != COMPLEX_TYPE)
	{
	  error_at (location,
		    "wrong type argument to unary exclamation mark");
	  return error_mark_node;
	}
      arg = c_objc_common_truthvalue_conversion (location, arg);
      ret = invert_truthvalue (arg);
      goto return_build_unary_op;

    case REALPART_EXPR:
      if (TREE_CODE (arg) == COMPLEX_CST)
	ret = TREE_REALPART (arg);
      else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
	ret = fold_build1 (REALPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg);
      else
	ret = arg;
      goto return_build_unary_op;

    case IMAGPART_EXPR:
      if (TREE_CODE (arg) == COMPLEX_CST)
	ret = TREE_IMAGPART (arg);
      else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
	ret = fold_build1 (IMAGPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg);
      else
	ret = omit_one_operand (TREE_TYPE (arg), integer_zero_node, arg);
      goto return_build_unary_op;

    case PREINCREMENT_EXPR:
    case POSTINCREMENT_EXPR:
    case PREDECREMENT_EXPR:
    case POSTDECREMENT_EXPR:

      /* Increment or decrement the real part of the value,
	 and don't change the imaginary part.  */
      if (typecode == COMPLEX_TYPE)
	{
	  tree real, imag;

	  pedwarn (location, OPT_pedantic, 
		   "ISO C does not support %<++%> and %<--%> on complex types");

	  arg = stabilize_reference (arg);
	  real = build_unary_op (EXPR_LOCATION (arg), REALPART_EXPR, arg, 1);
	  imag = build_unary_op (EXPR_LOCATION (arg), IMAGPART_EXPR, arg, 1);
	  real = build_unary_op (EXPR_LOCATION (arg), code, real, 1);
	  if (real == error_mark_node || imag == error_mark_node)
	    return error_mark_node;
	  ret = build2 (COMPLEX_EXPR, TREE_TYPE (arg),
			real, imag);
	  goto return_build_unary_op;
	}

      /* Report invalid types.  */

      if (typecode != POINTER_TYPE && typecode != FIXED_POINT_TYPE
	  && typecode != INTEGER_TYPE && typecode != REAL_TYPE)
	{
	  if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
	    error_at (location, "wrong type argument to increment");
	  else
	    error_at (location, "wrong type argument to decrement");

	  return error_mark_node;
	}

      {
	tree inc;

	argtype = TREE_TYPE (arg);

	/* Compute the increment.  */

	if (typecode == POINTER_TYPE)
	  {
	    /* If pointer target is an undefined struct,
	       we just cannot know how to do the arithmetic.  */
	    if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (argtype)))
	      {
		if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
		  error_at (location,
			    "increment of pointer to unknown structure");
		else
		  error_at (location,
			    "decrement of pointer to unknown structure"