gcc/cp/tree.cc

/* Language-dependent node constructors for parse phase of GNU compiler.
   Copyright (C) 1987-2022 Free Software Foundation, Inc.
   Hacked by Michael Tiemann (tiemann@cygnus.com)

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/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tree.h"
#include "cp-tree.h"
#include "gimple-expr.h"
#include "cgraph.h"
#include "stor-layout.h"
#include "print-tree.h"
#include "tree-iterator.h"
#include "tree-inline.h"
#include "debug.h"
#include "convert.h"
#include "gimplify.h"
#include "stringpool.h"
#include "attribs.h"
#include "flags.h"
#include "selftest.h"

static tree bot_manip (tree *, int *, void *);
static tree bot_replace (tree *, int *, void *);
static hashval_t list_hash_pieces (tree, tree, tree);
static tree build_target_expr (tree, tree, tsubst_flags_t);
static tree count_trees_r (tree *, int *, void *);
static tree verify_stmt_tree_r (tree *, int *, void *);

static tree handle_init_priority_attribute (tree *, tree, tree, int, bool *);
static tree handle_abi_tag_attribute (tree *, tree, tree, int, bool *);

/* If REF is an lvalue, returns the kind of lvalue that REF is.
   Otherwise, returns clk_none.  */

cp_lvalue_kind
lvalue_kind (const_tree ref)
{
  cp_lvalue_kind op1_lvalue_kind = clk_none;
  cp_lvalue_kind op2_lvalue_kind = clk_none;

  /* Expressions of reference type are sometimes wrapped in
     INDIRECT_REFs.  INDIRECT_REFs are just internal compiler
     representation, not part of the language, so we have to look
     through them.  */
  if (REFERENCE_REF_P (ref))
    return lvalue_kind (TREE_OPERAND (ref, 0));

  if (TREE_TYPE (ref)
      && TYPE_REF_P (TREE_TYPE (ref)))
    {
      /* unnamed rvalue references are rvalues */
      if (TYPE_REF_IS_RVALUE (TREE_TYPE (ref))
	  && TREE_CODE (ref) != PARM_DECL
	  && !VAR_P (ref)
	  && TREE_CODE (ref) != COMPONENT_REF
	  /* Functions are always lvalues.  */
	  && TREE_CODE (TREE_TYPE (TREE_TYPE (ref))) != FUNCTION_TYPE)
	{
	  op1_lvalue_kind = clk_rvalueref;
	  if (implicit_rvalue_p (ref))
	    op1_lvalue_kind |= clk_implicit_rval;
	  return op1_lvalue_kind;
	}

      /* lvalue references and named rvalue references are lvalues.  */
      return clk_ordinary;
    }

  if (ref == current_class_ptr)
    return clk_none;

  /* Expressions with cv void type are prvalues.  */
  if (TREE_TYPE (ref) && VOID_TYPE_P (TREE_TYPE (ref)))
    return clk_none;

  switch (TREE_CODE (ref))
    {
    case SAVE_EXPR:
      return clk_none;

      /* preincrements and predecrements are valid lvals, provided
	 what they refer to are valid lvals.  */
    case PREINCREMENT_EXPR:
    case PREDECREMENT_EXPR:
    case TRY_CATCH_EXPR:
    case REALPART_EXPR:
    case IMAGPART_EXPR:
    case VIEW_CONVERT_EXPR:
      return lvalue_kind (TREE_OPERAND (ref, 0));

    case ARRAY_REF:
      {
	tree op1 = TREE_OPERAND (ref, 0);
	if (TREE_CODE (TREE_TYPE (op1)) == ARRAY_TYPE)
	  {
	    op1_lvalue_kind = lvalue_kind (op1);
	    if (op1_lvalue_kind == clk_class)
	      /* in the case of an array operand, the result is an lvalue if
		 that operand is an lvalue and an xvalue otherwise */
	      op1_lvalue_kind = clk_rvalueref;
	    return op1_lvalue_kind;
	  }
	else
	  return clk_ordinary;
      }

    case MEMBER_REF:
    case DOTSTAR_EXPR:
      if (TREE_CODE (ref) == MEMBER_REF)
	op1_lvalue_kind = clk_ordinary;
      else
	op1_lvalue_kind = lvalue_kind (TREE_OPERAND (ref, 0));
      if (TYPE_PTRMEMFUNC_P (TREE_TYPE (TREE_OPERAND (ref, 1))))
	op1_lvalue_kind = clk_none;
      else if (op1_lvalue_kind == clk_class)
	/* The result of a .* expression whose second operand is a pointer to a
	   data member is an lvalue if the first operand is an lvalue and an
	   xvalue otherwise.  */
	op1_lvalue_kind = clk_rvalueref;
      return op1_lvalue_kind;

    case COMPONENT_REF:
      if (BASELINK_P (TREE_OPERAND (ref, 1)))
	{
	  tree fn = BASELINK_FUNCTIONS (TREE_OPERAND (ref, 1));

	  /* For static member function recurse on the BASELINK, we can get
	     here e.g. from reference_binding.  If BASELINK_FUNCTIONS is
	     OVERLOAD, the overload is resolved first if possible through
	     resolve_address_of_overloaded_function.  */
	  if (TREE_CODE (fn) == FUNCTION_DECL && DECL_STATIC_FUNCTION_P (fn))
	    return lvalue_kind (TREE_OPERAND (ref, 1));
	}
      op1_lvalue_kind = lvalue_kind (TREE_OPERAND (ref, 0));
      if (op1_lvalue_kind == clk_class)
	/* If E1 is an lvalue, then E1.E2 is an lvalue;
	   otherwise E1.E2 is an xvalue.  */
	op1_lvalue_kind = clk_rvalueref;

      /* Look at the member designator.  */
      if (!op1_lvalue_kind)
	;
      else if (is_overloaded_fn (TREE_OPERAND (ref, 1)))
	/* The "field" can be a FUNCTION_DECL or an OVERLOAD in some
	   situations.  If we're seeing a COMPONENT_REF, it's a non-static
	   member, so it isn't an lvalue. */
	op1_lvalue_kind = clk_none;
      else if (TREE_CODE (TREE_OPERAND (ref, 1)) != FIELD_DECL)
	/* This can be IDENTIFIER_NODE in a template.  */;
      else if (DECL_C_BIT_FIELD (TREE_OPERAND (ref, 1)))
	{
	  /* Clear the ordinary bit.  If this object was a class
	     rvalue we want to preserve that information.  */
	  op1_lvalue_kind &= ~clk_ordinary;
	  /* The lvalue is for a bitfield.  */
	  op1_lvalue_kind |= clk_bitfield;
	}
      else if (DECL_PACKED (TREE_OPERAND (ref, 1)))
	op1_lvalue_kind |= clk_packed;

      return op1_lvalue_kind;

    case STRING_CST:
    case COMPOUND_LITERAL_EXPR:
      return clk_ordinary;

    case CONST_DECL:
      /* CONST_DECL without TREE_STATIC are enumeration values and
	 thus not lvalues.  With TREE_STATIC they are used by ObjC++
	 in objc_build_string_object and need to be considered as
	 lvalues.  */
      if (! TREE_STATIC (ref))
	return clk_none;
      /* FALLTHRU */
    case VAR_DECL:
      if (VAR_P (ref) && DECL_HAS_VALUE_EXPR_P (ref))
	return lvalue_kind (DECL_VALUE_EXPR (CONST_CAST_TREE (ref)));

      if (TREE_READONLY (ref) && ! TREE_STATIC (ref)
	  && DECL_LANG_SPECIFIC (ref)
	  && DECL_IN_AGGR_P (ref))
	return clk_none;
      /* FALLTHRU */
    case INDIRECT_REF:
    case ARROW_EXPR:
    case PARM_DECL:
    case RESULT_DECL:
    case PLACEHOLDER_EXPR:
      return clk_ordinary;

      /* A scope ref in a template, left as SCOPE_REF to support later
	 access checking.  */
    case SCOPE_REF:
      gcc_assert (!type_dependent_expression_p (CONST_CAST_TREE (ref)));
      {
	tree op = TREE_OPERAND (ref, 1);
	if (TREE_CODE (op) == FIELD_DECL)
	  return (DECL_C_BIT_FIELD (op) ? clk_bitfield : clk_ordinary);
	else
	  return lvalue_kind (op);
      }

    case MAX_EXPR:
    case MIN_EXPR:
      /* Disallow <? and >? as lvalues if either argument side-effects.  */
      if (TREE_SIDE_EFFECTS (TREE_OPERAND (ref, 0))
	  || TREE_SIDE_EFFECTS (TREE_OPERAND (ref, 1)))
	return clk_none;
      op1_lvalue_kind = lvalue_kind (TREE_OPERAND (ref, 0));
      op2_lvalue_kind = lvalue_kind (TREE_OPERAND (ref, 1));
      break;

    case COND_EXPR:
      if (processing_template_decl)
	{
	  /* Within templates, a REFERENCE_TYPE will indicate whether
	     the COND_EXPR result is an ordinary lvalue or rvalueref.
	     Since REFERENCE_TYPEs are handled above, if we reach this
	     point, we know we got a plain rvalue.  Unless we have a
	     type-dependent expr, that is, but we shouldn't be testing
	     lvalueness if we can't even tell the types yet!  */
	  gcc_assert (!type_dependent_expression_p (CONST_CAST_TREE (ref)));
	  goto default_;
	}
      {
	tree op1 = TREE_OPERAND (ref, 1);
	if (!op1) op1 = TREE_OPERAND (ref, 0);
	tree op2 = TREE_OPERAND (ref, 2);
	op1_lvalue_kind = lvalue_kind (op1);
	op2_lvalue_kind = lvalue_kind (op2);
	if (!op1_lvalue_kind != !op2_lvalue_kind)
	  {
	    /* The second or the third operand (but not both) is a
	       throw-expression; the result is of the type
	       and value category of the other.  */
	    if (op1_lvalue_kind && TREE_CODE (op2) == THROW_EXPR)
	      op2_lvalue_kind = op1_lvalue_kind;
	    else if (op2_lvalue_kind && TREE_CODE (op1) == THROW_EXPR)
	      op1_lvalue_kind = op2_lvalue_kind;
	  }
      }
      break;

    case MODOP_EXPR:
      /* We expect to see unlowered MODOP_EXPRs only during
	 template processing.  */
      gcc_assert (processing_template_decl);
      return clk_ordinary;

    case MODIFY_EXPR:
    case TYPEID_EXPR:
      return clk_ordinary;

    case COMPOUND_EXPR:
      return lvalue_kind (TREE_OPERAND (ref, 1));

    case TARGET_EXPR:
      return clk_class;

    case VA_ARG_EXPR:
      return (CLASS_TYPE_P (TREE_TYPE (ref)) ? clk_class : clk_none);

    case CALL_EXPR:
      /* We can see calls outside of TARGET_EXPR in templates.  */
      if (CLASS_TYPE_P (TREE_TYPE (ref)))
	return clk_class;
      return clk_none;

    case FUNCTION_DECL:
      /* All functions (except non-static-member functions) are
	 lvalues.  */
      return (DECL_NONSTATIC_MEMBER_FUNCTION_P (ref)
	      ? clk_none : clk_ordinary);

    case BASELINK:
      /* We now represent a reference to a single static member function
	 with a BASELINK.  */
      /* This CONST_CAST is okay because BASELINK_FUNCTIONS returns
	 its argument unmodified and we assign it to a const_tree.  */
      return lvalue_kind (BASELINK_FUNCTIONS (CONST_CAST_TREE (ref)));

    case NON_DEPENDENT_EXPR:
    case PAREN_EXPR:
      return lvalue_kind (TREE_OPERAND (ref, 0));

    case TEMPLATE_PARM_INDEX:
      if (CLASS_TYPE_P (TREE_TYPE (ref)))
	/* A template parameter object is an lvalue.  */
	return clk_ordinary;
      return clk_none;

    default:
    default_:
      if (!TREE_TYPE (ref))
	return clk_none;
      if (CLASS_TYPE_P (TREE_TYPE (ref))
	  || TREE_CODE (TREE_TYPE (ref)) == ARRAY_TYPE)
	return clk_class;
      return clk_none;
    }

  /* If one operand is not an lvalue at all, then this expression is
     not an lvalue.  */
  if (!op1_lvalue_kind || !op2_lvalue_kind)
    return clk_none;

  /* Otherwise, it's an lvalue, and it has all the odd properties
     contributed by either operand.  */
  op1_lvalue_kind = op1_lvalue_kind | op2_lvalue_kind;
  /* It's not an ordinary lvalue if it involves any other kind.  */
  if ((op1_lvalue_kind & ~clk_ordinary) != clk_none)
    op1_lvalue_kind &= ~clk_ordinary;
  /* It can't be both a pseudo-lvalue and a non-addressable lvalue.
     A COND_EXPR of those should be wrapped in a TARGET_EXPR.  */
  if ((op1_lvalue_kind & (clk_rvalueref|clk_class))
      && (op1_lvalue_kind & (clk_bitfield|clk_packed)))
    op1_lvalue_kind = clk_none;
  return op1_lvalue_kind;
}

/* Returns the kind of lvalue that REF is, in the sense of [basic.lval].  */

cp_lvalue_kind
real_lvalue_p (const_tree ref)
{
  cp_lvalue_kind kind = lvalue_kind (ref);
  if (kind & (clk_rvalueref|clk_class))
    return clk_none;
  else
    return kind;
}

/* c-common wants us to return bool.  */

bool
lvalue_p (const_tree t)
{
  return real_lvalue_p (t);
}

/* This differs from lvalue_p in that xvalues are included.  */

bool
glvalue_p (const_tree ref)
{
  cp_lvalue_kind kind = lvalue_kind (ref);
  if (kind & clk_class)
    return false;
  else
    return (kind != clk_none);
}

/* This differs from glvalue_p in that class prvalues are included.  */

bool
obvalue_p (const_tree ref)
{
  return (lvalue_kind (ref) != clk_none);
}

/* Returns true if REF is an xvalue (the result of dereferencing an rvalue
   reference), false otherwise.  */

bool
xvalue_p (const_tree ref)
{
  return (lvalue_kind (ref) == clk_rvalueref);
}

/* True if REF is a bit-field.  */

bool
bitfield_p (const_tree ref)
{
  return (lvalue_kind (ref) & clk_bitfield);
}

/* C++-specific version of stabilize_reference.  */

tree
cp_stabilize_reference (tree ref)
{
  STRIP_ANY_LOCATION_WRAPPER (ref);
  switch (TREE_CODE (ref))
    {
    case NON_DEPENDENT_EXPR:
      /* We aren't actually evaluating this.  */
      return ref;

    /* We need to treat specially anything stabilize_reference doesn't
       handle specifically.  */
    case VAR_DECL:
    case PARM_DECL:
    case RESULT_DECL:
    CASE_CONVERT:
    case FLOAT_EXPR:
    case FIX_TRUNC_EXPR:
    case INDIRECT_REF:
    case COMPONENT_REF:
    case BIT_FIELD_REF:
    case ARRAY_REF:
    case ARRAY_RANGE_REF:
    case ERROR_MARK:
      break;
    default:
      cp_lvalue_kind kind = lvalue_kind (ref);
      if ((kind & ~clk_class) != clk_none)
	{
	  tree type = unlowered_expr_type (ref);
	  bool rval = !!(kind & clk_rvalueref);
	  type = cp_build_reference_type (type, rval);
	  /* This inhibits warnings in, eg, cxx_mark_addressable
	     (c++/60955).  */
	  warning_sentinel s (extra_warnings);
	  ref = build_static_cast (input_location, type, ref,
				   tf_error);
	}
    }

  return stabilize_reference (ref);
}

/* Test whether DECL is a builtin that may appear in a
   constant-expression. */

bool
builtin_valid_in_constant_expr_p (const_tree decl)
{
  STRIP_ANY_LOCATION_WRAPPER (decl);
  if (TREE_CODE (decl) != FUNCTION_DECL)
    /* Not a function.  */
    return false;
  if (DECL_BUILT_IN_CLASS (decl) != BUILT_IN_NORMAL)
    {
      if (fndecl_built_in_p (decl, BUILT_IN_FRONTEND))
	switch (DECL_FE_FUNCTION_CODE (decl))
	  {
	  case CP_BUILT_IN_IS_CONSTANT_EVALUATED:
	  case CP_BUILT_IN_SOURCE_LOCATION:
	  case CP_BUILT_IN_IS_CORRESPONDING_MEMBER:
	  case CP_BUILT_IN_IS_POINTER_INTERCONVERTIBLE_WITH_CLASS:
	    return true;
	  default:
	    break;
	  }
      /* Not a built-in.  */
      return false;
    }
  switch (DECL_FUNCTION_CODE (decl))
    {
      /* These always have constant results like the corresponding
	 macros/symbol.  */
    case BUILT_IN_FILE:
    case BUILT_IN_FUNCTION:
    case BUILT_IN_LINE:

      /* The following built-ins are valid in constant expressions
	 when their arguments are.  */
    case BUILT_IN_ADD_OVERFLOW_P:
    case BUILT_IN_SUB_OVERFLOW_P:
    case BUILT_IN_MUL_OVERFLOW_P:

      /* These have constant results even if their operands are
	 non-constant.  */
    case BUILT_IN_CONSTANT_P:
    case BUILT_IN_ATOMIC_ALWAYS_LOCK_FREE:
      return true;
    default:
      return false;
    }
}

/* Build a TARGET_EXPR, initializing the DECL with the VALUE.  */

static tree
build_target_expr (tree decl, tree value, tsubst_flags_t complain)
{
  tree t;
  tree type = TREE_TYPE (decl);

  value = mark_rvalue_use (value);

  gcc_checking_assert (VOID_TYPE_P (TREE_TYPE (value))
		       || TREE_TYPE (decl) == TREE_TYPE (value)
		       /* On ARM ctors return 'this'.  */
		       || (TYPE_PTR_P (TREE_TYPE (value))
			   && TREE_CODE (value) == CALL_EXPR)
		       || useless_type_conversion_p (TREE_TYPE (decl),
						     TREE_TYPE (value)));

  /* Set TREE_READONLY for optimization, such as gimplify_init_constructor
     moving a constant aggregate into .rodata.  */
  if (CP_TYPE_CONST_NON_VOLATILE_P (type)
      && !TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type)
      && !VOID_TYPE_P (TREE_TYPE (value))
      && reduced_constant_expression_p (value))
    TREE_READONLY (decl) = true;

  if (complain & tf_no_cleanup)
    /* The caller is building a new-expr and does not need a cleanup.  */
    t = NULL_TREE;
  else
    {
      t = cxx_maybe_build_cleanup (decl, complain);
      if (t == error_mark_node)
	return error_mark_node;
    }
  t = build4 (TARGET_EXPR, type, decl, value, t, NULL_TREE);
  if (location_t eloc = cp_expr_location (value))
    SET_EXPR_LOCATION (t, eloc);
  /* We always set TREE_SIDE_EFFECTS so that expand_expr does not
     ignore the TARGET_EXPR.  If there really turn out to be no
     side-effects, then the optimizer should be able to get rid of
     whatever code is generated anyhow.  */
  TREE_SIDE_EFFECTS (t) = 1;

  return t;
}

/* Return an undeclared local temporary of type TYPE for use in building a
   TARGET_EXPR.  */

tree
build_local_temp (tree type)
{
  tree slot = build_decl (input_location,
			  VAR_DECL, NULL_TREE, type);
  DECL_ARTIFICIAL (slot) = 1;
  DECL_IGNORED_P (slot) = 1;
  DECL_CONTEXT (slot) = current_function_decl;
  layout_decl (slot, 0);
  return slot;
}

/* Return whether DECL is such a local temporary (or one from
   create_tmp_var_raw).  */

bool
is_local_temp (tree decl)
{
  return (VAR_P (decl) && DECL_ARTIFICIAL (decl)
	  && !TREE_STATIC (decl));
}

/* Set various status flags when building an AGGR_INIT_EXPR object T.  */

static void
process_aggr_init_operands (tree t)
{
  bool side_effects;

  side_effects = TREE_SIDE_EFFECTS (t);
  if (!side_effects)
    {
      int i, n;
      n = TREE_OPERAND_LENGTH (t);
      for (i = 1; i < n; i++)
	{
	  tree op = TREE_OPERAND (t, i);
	  if (op && TREE_SIDE_EFFECTS (op))
	    {
	      side_effects = 1;
	      break;
	    }
	}
    }
  TREE_SIDE_EFFECTS (t) = side_effects;
}

/* Build an AGGR_INIT_EXPR of class tcc_vl_exp with the indicated RETURN_TYPE,
   FN, and SLOT.  NARGS is the number of call arguments which are specified
   as a tree array ARGS.  */

static tree
build_aggr_init_array (tree return_type, tree fn, tree slot, int nargs,
		       tree *args)
{
  tree t;
  int i;

  t = build_vl_exp (AGGR_INIT_EXPR, nargs + 3);
  TREE_TYPE (t) = return_type;
  AGGR_INIT_EXPR_FN (t) = fn;
  AGGR_INIT_EXPR_SLOT (t) = slot;
  for (i = 0; i < nargs; i++)
    AGGR_INIT_EXPR_ARG (t, i) = args[i];
  process_aggr_init_operands (t);
  return t;
}

/* INIT is a CALL_EXPR or AGGR_INIT_EXPR which needs info about its
   target.  TYPE is the type to be initialized.

   Build an AGGR_INIT_EXPR to represent the initialization.  This function
   differs from build_cplus_new in that an AGGR_INIT_EXPR can only be used
   to initialize another object, whereas a TARGET_EXPR can either
   initialize another object or create its own temporary object, and as a
   result building up a TARGET_EXPR requires that the type's destructor be
   callable.  */

tree
build_aggr_init_expr (tree type, tree init)
{
  tree fn;
  tree slot;
  tree rval;
  int is_ctor;

  gcc_assert (!VOID_TYPE_P (type));

  /* Don't build AGGR_INIT_EXPR in a template.  */
  if (processing_template_decl)
    return init;

  fn = cp_get_callee (init);
  if (fn == NULL_TREE)
    return convert (type, init);

  is_ctor = (TREE_CODE (fn) == ADDR_EXPR
	     && TREE_CODE (TREE_OPERAND (fn, 0)) == FUNCTION_DECL
	     && DECL_CONSTRUCTOR_P (TREE_OPERAND (fn, 0)));

  /* We split the CALL_EXPR into its function and its arguments here.
     Then, in expand_expr, we put them back together.  The reason for
     this is that this expression might be a default argument
     expression.  In that case, we need a new temporary every time the
     expression is used.  That's what break_out_target_exprs does; it
     replaces every AGGR_INIT_EXPR with a copy that uses a fresh
     temporary slot.  Then, expand_expr builds up a call-expression
     using the new slot.  */

  /* If we don't need to use a constructor to create an object of this
     type, don't mess with AGGR_INIT_EXPR.  */
  if (is_ctor || TREE_ADDRESSABLE (type))
    {
      slot = build_local_temp (type);

      if (TREE_CODE (init) == CALL_EXPR)
	{
	  rval = build_aggr_init_array (void_type_node, fn, slot,
					call_expr_nargs (init),
					CALL_EXPR_ARGP (init));
	  AGGR_INIT_FROM_THUNK_P (rval)
	    = CALL_FROM_THUNK_P (init);
	}
      else
	{
	  rval = build_aggr_init_array (void_type_node, fn, slot,
					aggr_init_expr_nargs (init),
					AGGR_INIT_EXPR_ARGP (init));
	  AGGR_INIT_FROM_THUNK_P (rval)
	    = AGGR_INIT_FROM_THUNK_P (init);
	}
      TREE_SIDE_EFFECTS (rval) = 1;
      AGGR_INIT_VIA_CTOR_P (rval) = is_ctor;
      TREE_NOTHROW (rval) = TREE_NOTHROW (init);
      CALL_EXPR_OPERATOR_SYNTAX (rval) = CALL_EXPR_OPERATOR_SYNTAX (init);
      CALL_EXPR_ORDERED_ARGS (rval) = CALL_EXPR_ORDERED_ARGS (init);
      CALL_EXPR_REVERSE_ARGS (rval) = CALL_EXPR_REVERSE_ARGS (init);
    }
  else
    rval = init;

  return rval;
}

/* INIT is a CALL_EXPR or AGGR_INIT_EXPR which needs info about its
   target.  TYPE is the type that this initialization should appear to
   have.

   Build an encapsulation of the initialization to perform
   and return it so that it can be processed by language-independent
   and language-specific expression expanders.  */

tree
build_cplus_new (tree type, tree init, tsubst_flags_t complain)
{
  /* This function should cope with what build_special_member_call
     can produce.  When performing parenthesized aggregate initialization,
     it can produce a { }.  */
  if (BRACE_ENCLOSED_INITIALIZER_P (init))
    {
      gcc_assert (cxx_dialect >= cxx20);
      return finish_compound_literal (type, init, complain);
    }

  tree rval = build_aggr_init_expr (type, init);
  tree slot;

  if (init == error_mark_node)
    return error_mark_node;

  if (!complete_type_or_maybe_complain (type, init, complain))
    return error_mark_node;

  /* Make sure that we're not trying to create an instance of an
     abstract class.  */
  if (abstract_virtuals_error_sfinae (NULL_TREE, type, complain))
    return error_mark_node;

  if (TREE_CODE (rval) == AGGR_INIT_EXPR)
    slot = AGGR_INIT_EXPR_SLOT (rval);
  else if (TREE_CODE (rval) == CALL_EXPR
	   || TREE_CODE (rval) == CONSTRUCTOR)
    slot = build_local_temp (type);
  else
    return rval;

  rval = build_target_expr (slot, rval, complain);

  if (rval != error_mark_node)
    TARGET_EXPR_IMPLICIT_P (rval) = 1;

  return rval;
}

/* Subroutine of build_vec_init_expr: Build up a single element
   intialization as a proxy for the full array initialization to get things
   marked as used and any appropriate diagnostics.

   This used to be necessary because we were deferring building the actual
   constructor calls until gimplification time; now we only do it to set
   VEC_INIT_EXPR_IS_CONSTEXPR.

   We assume that init is either NULL_TREE, {}, void_type_node (indicating
   value-initialization), or another array to copy.  */

static tree
build_vec_init_elt (tree type, tree init, tsubst_flags_t complain)
{
  tree inner_type = strip_array_types (type);

  if (integer_zerop (array_type_nelts_total (type))
      || !CLASS_TYPE_P (inner_type))
    /* No interesting initialization to do.  */
    return integer_zero_node;
  if (init && BRACE_ENCLOSED_INITIALIZER_P (init))
    {
      /* Even if init has initializers for some array elements,
	 we're interested in the {}-init of trailing elements.	*/
      if (CP_AGGREGATE_TYPE_P (inner_type))
	{
	  tree empty = build_constructor (init_list_type_node, nullptr);
	  return digest_init (inner_type, empty, complain);
	}
      else
	/* It's equivalent to value-init.  */
	init = void_type_node;
    }
  if (init == void_type_node)
    return build_value_init (inner_type, complain);

  releasing_vec argvec;
  if (init && !BRACE_ENCLOSED_INITIALIZER_P (init))
    {
      gcc_assert (same_type_ignoring_top_level_qualifiers_p
		  (type, TREE_TYPE (init)));
      tree init_type = strip_array_types (TREE_TYPE (init));
      tree dummy = build_dummy_object (init_type);
      if (!lvalue_p (init))
	dummy = move (dummy);
      argvec->quick_push (dummy);
    }
  init = build_special_member_call (NULL_TREE, complete_ctor_identifier,
				    &argvec, inner_type, LOOKUP_NORMAL,
				    complain);

  /* For a trivial constructor, build_over_call creates a TARGET_EXPR.  But
     we don't want one here because we aren't creating a temporary.  */
  if (TREE_CODE (init) == TARGET_EXPR)
    init = TARGET_EXPR_INITIAL (init);

  return init;
}

/* Return a TARGET_EXPR which expresses the initialization of an array to
   be named later, either default-initialization or copy-initialization
   from another array of the same type.  */

tree
build_vec_init_expr (tree type, tree init, tsubst_flags_t complain)
{
  if (tree vi = get_vec_init_expr (init))
    return vi;

  tree elt_init;
  if (init && TREE_CODE (init) == CONSTRUCTOR
      && !BRACE_ENCLOSED_INITIALIZER_P (init))
    /* We built any needed constructor calls in digest_init.  */
    elt_init = init;
  else
    elt_init = build_vec_init_elt (type, init, complain);

  bool value_init = false;
  if (init == void_type_node)
    {
      value_init = true;
      init = NULL_TREE;
    }

  tree slot = build_local_temp (type);
  init = build2 (VEC_INIT_EXPR, type, slot, init);
  TREE_SIDE_EFFECTS (init) = true;
  SET_EXPR_LOCATION (init, input_location);

  if (cxx_dialect >= cxx11)
    {
      bool cx = potential_constant_expression (elt_init);
      if (BRACE_ENCLOSED_INITIALIZER_P (init))
	cx &= potential_constant_expression (init);
      VEC_INIT_EXPR_IS_CONSTEXPR (init) = cx;
    }
  VEC_INIT_EXPR_VALUE_INIT (init) = value_init;

  return init;
}

/* Call build_vec_init to expand VEC_INIT into TARGET (for which NULL_TREE
   means VEC_INIT_EXPR_SLOT).  */

tree
expand_vec_init_expr (tree target, tree vec_init, tsubst_flags_t complain,
		      vec<tree,va_gc> **flags)
{
  iloc_sentinel ils = EXPR_LOCATION (vec_init);

  if (!target)
    target = VEC_INIT_EXPR_SLOT (vec_init);
  tree init = VEC_INIT_EXPR_INIT (vec_init);
  int from_array = (init && TREE_CODE (TREE_TYPE (init)) == ARRAY_TYPE);
  return build_vec_init (target, NULL_TREE, init,
			 VEC_INIT_EXPR_VALUE_INIT (vec_init),
			 from_array, complain, flags);
}

/* Give a helpful diagnostic for a non-constexpr VEC_INIT_EXPR in a context
   that requires a constant expression.  */

void
diagnose_non_constexpr_vec_init (tree expr)
{
  tree type = TREE_TYPE (VEC_INIT_EXPR_SLOT (expr));
  tree init, elt_init;
  if (VEC_INIT_EXPR_VALUE_INIT (expr))
    init = void_type_node;
  else
    init = VEC_INIT_EXPR_INIT (expr);

  elt_init = build_vec_init_elt (type, init, tf_warning_or_error);
  require_potential_constant_expression (elt_init);
}

tree
build_array_copy (tree init)
{
  return get_target_expr (build_vec_init_expr
			  (TREE_TYPE (init), init, tf_warning_or_error));
}

/* Build a TARGET_EXPR using INIT to initialize a new temporary of the
   indicated TYPE.  */

tree
build_target_expr_with_type (tree init, tree type, tsubst_flags_t complain)
{
  gcc_assert (!VOID_TYPE_P (type));
  gcc_assert (!VOID_TYPE_P (TREE_TYPE (init)));

  if (TREE_CODE (init) == TARGET_EXPR
      || init == error_mark_node)
    return init;
  else if (CLASS_TYPE_P (type) && type_has_nontrivial_copy_init (type)
	   && TREE_CODE (init) != COND_EXPR
	   && TREE_CODE (init) != CONSTRUCTOR
	   && TREE_CODE (init) != VA_ARG_EXPR
	   && TREE_CODE (init) != CALL_EXPR)
    /* We need to build up a copy constructor call.  COND_EXPR is a special
       case because we already have copies on the arms and we don't want
       another one here.  A CONSTRUCTOR is aggregate initialization, which
       is handled separately.  A VA_ARG_EXPR is magic creation of an
       aggregate; there's no additional work to be done.  A CALL_EXPR
       already creates a prvalue.  */
    return force_rvalue (init, complain);

  return force_target_expr (type, init, complain);
}

/* Like the above function, but without the checking.  This function should
   only be used by code which is deliberately trying to subvert the type
   system, such as call_builtin_trap.  Or build_over_call, to avoid
   infinite recursion.  */

tree
force_target_expr (tree type, tree init, tsubst_flags_t complain)
{
  tree slot;

  gcc_assert (!VOID_TYPE_P (type));

  slot = build_local_temp (type);
  return build_target_expr (slot, init, complain);
}

/* Like build_target_expr_with_type, but use the type of INIT.  */

tree
get_target_expr_sfinae (tree init, tsubst_flags_t complain)
{
  if (TREE_CODE (init) == AGGR_INIT_EXPR)
    return build_target_expr (AGGR_INIT_EXPR_SLOT (init), init, complain);
  else if (TREE_CODE (init) == VEC_INIT_EXPR)
    return build_target_expr (VEC_INIT_EXPR_SLOT (init), init, complain);
  else
    {
      init = convert_bitfield_to_declared_type (init);
      return build_target_expr_with_type (init, TREE_TYPE (init), complain);
    }
}

tree
get_target_expr (tree init)
{
  return get_target_expr_sfinae (init, tf_warning_or_error);
}

/* If EXPR is a bitfield reference, convert it to the declared type of
   the bitfield, and return the resulting expression.  Otherwise,
   return EXPR itself.  */

tree
convert_bitfield_to_declared_type (tree expr)
{
  tree bitfield_type;

  bitfield_type = is_bitfield_expr_with_lowered_type (expr);
  if (bitfield_type)
    expr = convert_to_integer_nofold (TYPE_MAIN_VARIANT (bitfield_type),
				      expr);
  return expr;
}

/* EXPR is being used in an rvalue context.  Return a version of EXPR
   that is marked as an rvalue.  */

tree
rvalue (tree expr)
{
  tree type;

  if (error_operand_p (expr))
    return expr;

  expr = mark_rvalue_use (expr);

  /* [basic.lval]

     Non-class rvalues always have cv-unqualified types.  */
  type = TREE_TYPE (expr);
  if (!CLASS_TYPE_P (type) && cv_qualified_p (type))
    type = cv_unqualified (type);

  /* We need to do this for rvalue refs as well to get the right answer
     from decltype; see c++/36628.  */
  if (!processing_template_decl && glvalue_p (expr))
    {
      /* But don't use this function for class lvalues; use move (to treat an
	 lvalue as an xvalue) or force_rvalue (to make a prvalue copy).  */
      gcc_checking_assert (!CLASS_TYPE_P (type));
      expr = build1 (NON_LVALUE_EXPR, type, expr);
    }
  else if (type != TREE_TYPE (expr))
    expr = build_nop (type, expr);

  return expr;
}


struct cplus_array_info
{
  tree type;
  tree domain;
};

struct cplus_array_hasher : ggc_ptr_hash<tree_node>
{
  typedef cplus_array_info *compare_type;

  static hashval_t hash (tree t);
  static bool equal (tree, cplus_array_info *);
};

/* Hash an ARRAY_TYPE.  K is really of type `tree'.  */

hashval_t
cplus_array_hasher::hash (tree t)
{
  hashval_t hash;

  hash = TYPE_UID (TREE_TYPE (t));
  if (TYPE_DOMAIN (t))
    hash ^= TYPE_UID (TYPE_DOMAIN (t));
  return hash;
}

/* Compare two ARRAY_TYPEs.  K1 is really of type `tree', K2 is really
   of type `cplus_array_info*'. */

bool
cplus_array_hasher::equal (tree t1, cplus_array_info *t2)
{
  return (TREE_TYPE (t1) == t2->type && TYPE_DOMAIN (t1) == t2->domain);
}

/* Hash table containing dependent array types, which are unsuitable for
   the language-independent type hash table.  */
static GTY (()) hash_table<cplus_array_hasher> *cplus_array_htab;

/* Build an ARRAY_TYPE without laying it out.  */

static tree
build_min_array_type (tree elt_type, tree index_type)
{
  tree t = cxx_make_type (ARRAY_TYPE);
  TREE_TYPE (t) = elt_type;
  TYPE_DOMAIN (t) = index_type;
  return t;
}

/* Set TYPE_CANONICAL like build_array_type_1, but using
   build_cplus_array_type.  */

static void
set_array_type_canon (tree t, tree elt_type, tree index_type, bool dep)
{
  /* Set the canonical type for this new node.  */
  if (TYPE_STRUCTURAL_EQUALITY_P (elt_type)
      || (index_type && TYPE_STRUCTURAL_EQUALITY_P (index_type)))
    SET_TYPE_STRUCTURAL_EQUALITY (t);
  else if (TYPE_CANONICAL (elt_type) != elt_type
	   || (index_type && TYPE_CANONICAL (index_type) != index_type))
    TYPE_CANONICAL (t)
      = build_cplus_array_type (TYPE_CANONICAL (elt_type),
				index_type
				? TYPE_CANONICAL (index_type) : index_type,
				dep);
  else
    TYPE_CANONICAL (t) = t;
}

/* Like build_array_type, but handle special C++ semantics: an array of a
   variant element type is a variant of the array of the main variant of
   the element type.  IS_DEPENDENT is -ve if we should determine the
   dependency.  Otherwise its bool value indicates dependency.  */

tree
build_cplus_array_type (tree elt_type, tree index_type, int dependent)
{
  tree t;

  if (elt_type == error_mark_node || index_type == error_mark_node)
    return error_mark_node;

  if (dependent < 0)
    dependent = (uses_template_parms (elt_type)
		 || (index_type && uses_template_parms (index_type)));

  if (elt_type != TYPE_MAIN_VARIANT (elt_type))
    /* Start with an array of the TYPE_MAIN_VARIANT.  */
    t = build_cplus_array_type (TYPE_MAIN_VARIANT (elt_type),
				index_type, dependent);
  else if (dependent)
    {
      /* Since type_hash_canon calls layout_type, we need to use our own
	 hash table.  */
      cplus_array_info cai;
      hashval_t hash;

      if (cplus_array_htab == NULL)
	cplus_array_htab = hash_table<cplus_array_hasher>::create_ggc (61);
      
      hash = TYPE_UID (elt_type);
      if (index_type)
	hash ^= TYPE_UID (index_type);
      cai.type = elt_type;
      cai.domain = index_type;

      tree *e = cplus_array_htab->find_slot_with_hash (&cai, hash, INSERT); 
      if (*e)
	/* We have found the type: we're done.  */
	return (tree) *e;
      else
	{
	  /* Build a new array type.  */
	  t = build_min_array_type (elt_type, index_type);

	  /* Store it in the hash table. */
	  *e = t;

	  /* Set the canonical type for this new node.  */
	  set_array_type_canon (t, elt_type, index_type, dependent);

	  /* Mark it as dependent now, this saves time later.  */
	  TYPE_DEPENDENT_P_VALID (t) = true;
	  TYPE_DEPENDENT_P (t) = true;
	}
    }
  else
    {
      bool typeless_storage = is_byte_access_type (elt_type);
      t = build_array_type (elt_type, index_type, typeless_storage);

      /* Mark as non-dependenty now, this will save time later.  */
      TYPE_DEPENDENT_P_VALID (t) = true;
    }

  /* Now check whether we already have this array variant.  */
  if (elt_type != TYPE_MAIN_VARIANT (elt_type))
    {
      tree m = t;
      for (t = m; t; t = TYPE_NEXT_VARIANT (t))
	if (TREE_TYPE (t) == elt_type
	    && TYPE_NAME (t) == NULL_TREE
	    && TYPE_ATTRIBUTES (t) == NULL_TREE)
	  break;
      if (!t)
	{
	  t = build_min_array_type (elt_type, index_type);
	  /* Mark dependency now, this saves time later.  */
	  TYPE_DEPENDENT_P_VALID (t) = true;
	  TYPE_DEPENDENT_P (t) = dependent;
	  set_array_type_canon (t, elt_type, index_type, dependent);
	  if (!dependent)
	    {
	      layout_type (t);
	      /* Make sure sizes are shared with the main variant.
		 layout_type can't be called after setting TYPE_NEXT_VARIANT,
		 as it will overwrite alignment etc. of all variants.  */
	      TYPE_SIZE (t) = TYPE_SIZE (m);
	      TYPE_SIZE_UNIT (t) = TYPE_SIZE_UNIT (m);
	      TYPE_TYPELESS_STORAGE (t) = TYPE_TYPELESS_STORAGE (m);
	    }

	  TYPE_MAIN_VARIANT (t) = m;
	  TYPE_NEXT_VARIANT (t) = TYPE_NEXT_VARIANT (m);
	  TYPE_NEXT_VARIANT (m) = t;
	}
    }

  /* Avoid spurious warnings with VLAs (c++/54583).  */
  if (TYPE_SIZE (t) && EXPR_P (TYPE_SIZE (t)))
    suppress_warning (TYPE_SIZE (t), OPT_Wunused);

  /* Push these needs up to the ARRAY_TYPE so that initialization takes
     place more easily.  */
  bool needs_ctor = (TYPE_NEEDS_CONSTRUCTING (t)
		     = TYPE_NEEDS_CONSTRUCTING (elt_type));
  bool needs_dtor = (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (t)
		     = TYPE_HAS_NONTRIVIAL_DESTRUCTOR (elt_type));

  if (!dependent && t == TYPE_MAIN_VARIANT (t)
      && !COMPLETE_TYPE_P (t) && COMPLETE_TYPE_P (elt_type))
    {
      /* The element type has been completed since the last time we saw
	 this array type; update the layout and 'tor flags for any variants
	 that need it.  */
      layout_type (t);
      for (tree v = TYPE_NEXT_VARIANT (t); v; v = TYPE_NEXT_VARIANT (v))
	{
	  TYPE_NEEDS_CONSTRUCTING (v) = needs_ctor;
	  TYPE_HAS_NONTRIVIAL_DESTRUCTOR (v) = needs_dtor;
	}
    }

  return t;
}

/* Return an ARRAY_TYPE with element type ELT and length N.  */

tree
build_array_of_n_type (tree elt, int n)
{
  return build_cplus_array_type (elt, build_index_type (size_int (n - 1)));
}

/* True iff T is an array of unknown bound.  */

bool
array_of_unknown_bound_p (const_tree t)
{
  return (TREE_CODE (t) == ARRAY_TYPE
	  && !TYPE_DOMAIN (t));
}

/* True iff T is an N3639 array of runtime bound (VLA).  These were approved
   for C++14 but then removed.  This should only be used for N3639
   specifically; code wondering more generally if something is a VLA should use
   vla_type_p.  */

bool
array_of_runtime_bound_p (tree t)
{
  if (!t || TREE_CODE (t) != ARRAY_TYPE)
    return false;
  if (variably_modified_type_p (TREE_TYPE (t), NULL_TREE))
    return false;
  tree dom = TYPE_DOMAIN (t);
  if (!dom)
    return false;
  tree max = TYPE_MAX_VALUE (dom);
  return (!potential_rvalue_constant_expression (max)
	  || (!value_dependent_expression_p (max) && !TREE_CONSTANT (max)));
}

/* True iff T is a variable length array.  */

bool
vla_type_p (tree t)
{
  for (; t && TREE_CODE (t) == ARRAY_TYPE;
       t = TREE_TYPE (t))
    if (tree dom = TYPE_DOMAIN (t))
      {
	tree max = TYPE_MAX_VALUE (dom);
	if (!potential_rvalue_constant_expression (max)
	    || (!value_dependent_expression_p (max) && !TREE_CONSTANT (max)))
	  return true;
      }
  return false;
}


/* Return a reference type node of MODE referring to TO_TYPE.  If MODE
   is VOIDmode the standard pointer mode will be picked.  If RVAL is
   true, return an rvalue reference type, otherwise return an lvalue
   reference type.  If a type node exists, reuse it, otherwise create
   a new one.  */
tree
cp_build_reference_type_for_mode (tree to_type, machine_mode mode, bool rval)
{
  tree lvalue_ref, t;

  if (to_type == error_mark_node)
    return error_mark_node;

  if (TYPE_REF_P (to_type))
    {
      rval = rval && TYPE_REF_IS_RVALUE (to_type);
      to_type = TREE_TYPE (to_type);
    }

  lvalue_ref = build_reference_type_for_mode (to_type, mode, false);

  if (!rval)
    return lvalue_ref;

  /* This code to create rvalue reference types is based on and tied
     to the code creating lvalue reference types in the middle-end
     functions build_reference_type_for_mode and build_reference_type.

     It works by putting the rvalue reference type nodes after the
     lvalue reference nodes in the TYPE_NEXT_REF_TO linked list, so
     they will effectively be ignored by the middle end.  */

  for (t = lvalue_ref; (t = TYPE_NEXT_REF_TO (t)); )
    if (TYPE_REF_IS_RVALUE (t))
      return t;

  t = build_distinct_type_copy (lvalue_ref);

  TYPE_REF_IS_RVALUE (t) = true;
  TYPE_NEXT_REF_TO (t) = TYPE_NEXT_REF_TO (lvalue_ref);
  TYPE_NEXT_REF_TO (lvalue_ref) = t;

  if (TYPE_STRUCTURAL_EQUALITY_P (to_type))
    SET_TYPE_STRUCTURAL_EQUALITY (t);
  else if (TYPE_CANONICAL (to_type) != to_type)
    TYPE_CANONICAL (t) 
      = cp_build_reference_type_for_mode (TYPE_CANONICAL (to_type), mode, rval);
  else
    TYPE_CANONICAL (t) = t;

  layout_type (t);

  return t;

}

/* Return a reference type node referring to TO_TYPE.  If RVAL is
   true, return an rvalue reference type, otherwise return an lvalue
   reference type.  If a type node exists, reuse it, otherwise create
   a new one.  */
tree
cp_build_reference_type (tree to_type, bool rval)
{
  return cp_build_reference_type_for_mode (to_type, VOIDmode, rval);
}

/* Returns EXPR cast to rvalue reference type, like std::move.  */

tree
move (tree expr)
{
  tree type = TREE_TYPE (expr);
  gcc_assert (!TYPE_REF_P (type));
  if (xvalue_p (expr))
    return expr;
  type = cp_build_reference_type (type, /*rval*/true);
  return build_static_cast (input_location, type, expr,
			    tf_warning_or_error);
}

/* Used by the C++ front end to build qualified array types.  However,
   the C version of this function does not properly maintain canonical
   types (which are not used in C).  */
tree
c_build_qualified_type (tree type, int type_quals, tree /* orig_qual_type */,
			size_t /* orig_qual_indirect */)
{
  return cp_build_qualified_type (type, type_quals);
}


/* Make a variant of TYPE, qualified with the TYPE_QUALS.  Handles
   arrays correctly.  In particular, if TYPE is an array of T's, and
   TYPE_QUALS is non-empty, returns an array of qualified T's.

   FLAGS determines how to deal with ill-formed qualifications. If
   tf_ignore_bad_quals is set, then bad qualifications are dropped
   (this is permitted if TYPE was introduced via a typedef or template
   type parameter). If bad qualifications are dropped and tf_warning
   is set, then a warning is issued for non-const qualifications.  If
   tf_ignore_bad_quals is not set and tf_error is not set, we
   return error_mark_node. Otherwise, we issue an error, and ignore
   the qualifications.

   Qualification of a reference type is valid when the reference came
   via a typedef or template type argument. [dcl.ref] No such
   dispensation is provided for qualifying a function type.  [dcl.fct]
   DR 295 queries this and the proposed resolution brings it into line
   with qualifying a reference.  We implement the DR.  We also behave
   in a similar manner for restricting non-pointer types.  */

tree
cp_build_qualified_type_real (tree type,
			      int type_quals,
			      tsubst_flags_t complain)
{
  tree result;
  int bad_quals = TYPE_UNQUALIFIED;

  if (type == error_mark_node)
    return type;

  if (type_quals == cp_type_quals (type))
    return type;

  if (TREE_CODE (type) == ARRAY_TYPE)
    {
      /* In C++, the qualification really applies to the array element
	 type.  Obtain the appropriately qualified element type.  */
      tree t;
      tree element_type
	= cp_build_qualified_type_real (TREE_TYPE (type),
					type_quals,
					complain);

      if (element_type == error_mark_node)
	return error_mark_node;

      /* See if we already have an identically qualified type.  Tests
	 should be equivalent to those in check_qualified_type.  */
      for (t = TYPE_MAIN_VARIANT (type); t; t = TYPE_NEXT_VARIANT (t))
	if (TREE_TYPE (t) == element_type
	    && TYPE_NAME (t) == TYPE_NAME (type)
	    && TYPE_CONTEXT (t) == TYPE_CONTEXT (type)
	    && attribute_list_equal (TYPE_ATTRIBUTES (t),
				     TYPE_ATTRIBUTES (type)))
	  break;

      if (!t)
	{
	  /* If we already know the dependentness, tell the array type
	     constructor.  This is important for module streaming, as we cannot
	     dynamically determine that on read in.  */
	  t = build_cplus_array_type (element_type, TYPE_DOMAIN (type),
				      TYPE_DEPENDENT_P_VALID (type)
				      ? int (TYPE_DEPENDENT_P (type)) : -1);

	  /* Keep the typedef name.  */
	  if (TYPE_NAME (t) != TYPE_NAME (type))
	    {
	      t = build_variant_type_copy (t);
	      TYPE_NAME (t) = TYPE_NAME (type);
	      SET_TYPE_ALIGN (t, TYPE_ALIGN (type));
	      TYPE_USER_ALIGN (t) = TYPE_USER_ALIGN (type);
	    }
	}

      /* Even if we already had this variant, we update
	 TYPE_NEEDS_CONSTRUCTING and TYPE_HAS_NONTRIVIAL_DESTRUCTOR in case
	 they changed since the variant was originally created.

	 This seems hokey; if there is some way to use a previous
	 variant *without* coming through here,
	 TYPE_NEEDS_CONSTRUCTING will never be updated.  */
      TYPE_NEEDS_CONSTRUCTING (t)
	= TYPE_NEEDS_CONSTRUCTING (TYPE_MAIN_VARIANT (element_type));
      TYPE_HAS_NONTRIVIAL_DESTRUCTOR (t)
	= TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TYPE_MAIN_VARIANT (element_type));
      return t;
    }
  else if (TREE_CODE (type) == TYPE_PACK_EXPANSION)
    {
      tree t = PACK_EXPANSION_PATTERN (type);

      t = cp_build_qualified_type_real (t, type_quals, complain);
      return make_pack_expansion (t, complain);
    }

  /* A reference or method type shall not be cv-qualified.
     [dcl.ref], [dcl.fct].  This used to be an error, but as of DR 295
     (in CD1) we always ignore extra cv-quals on functions.  */

  /* [dcl.ref/1] Cv-qualified references are ill-formed except when
     the cv-qualifiers are introduced through the use of a typedef-name
     ([dcl.typedef], [temp.param]) or decltype-specifier
     ([dcl.type.decltype]),in which case the cv-qualifiers are
     ignored.  */
  if (type_quals & (TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE)
      && (TYPE_REF_P (type)
	  || FUNC_OR_METHOD_TYPE_P (type)))
    {
      if (TYPE_REF_P (type)
	  && (!typedef_variant_p (type) || FUNC_OR_METHOD_TYPE_P (type)))
	bad_quals |= type_quals & (TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE);
      type_quals &= ~(TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE);
    }

  /* But preserve any function-cv-quals on a FUNCTION_TYPE.  */
  if (TREE_CODE (type) == FUNCTION_TYPE)
    type_quals |= type_memfn_quals (type);

  /* A restrict-qualified type must be a pointer (or reference)
     to object or incomplete type. */
  if ((type_quals & TYPE_QUAL_RESTRICT)
      && TREE_CODE (type) != TEMPLATE_TYPE_PARM
      && TREE_CODE (type) != TYPENAME_TYPE
      && !INDIRECT_TYPE_P (type))
    {
      bad_quals |= TYPE_QUAL_RESTRICT;
      type_quals &= ~TYPE_QUAL_RESTRICT;
    }

  if (bad_quals == TYPE_UNQUALIFIED
      || (complain & tf_ignore_bad_quals))
    /*OK*/;
  else if (!(complain & tf_error))
    return error_mark_node;
  else
    {
      tree bad_type = build_qualified_type (ptr_type_node, bad_quals);
      error ("%qV qualifiers cannot be applied to %qT",
	     bad_type, type);
    }

  /* Retrieve (or create) the appropriately qualified variant.  */
  result = build_qualified_type (type, type_quals);

  return result;
}

/* Return TYPE with const and volatile removed.  */

tree
cv_unqualified (tree type)
{
  int quals;

  if (type == error_mark_node)
    return type;

  quals = cp_type_quals (type);
  quals &= ~(TYPE_QUAL_CONST|TYPE_QUAL_VOLATILE);
  return cp_build_qualified_type (type, quals);
}

/* Subroutine of strip_typedefs.  We want to apply to RESULT the attributes
   from ATTRIBS that affect type identity, and no others.  If any are not
   applied, set *remove_attributes to true.  */

static tree
apply_identity_attributes (tree result, tree attribs, bool *remove_attributes)
{
  tree first_ident = NULL_TREE;
  tree new_attribs = NULL_TREE;
  tree *p = &new_attribs;

  if (OVERLOAD_TYPE_P (result))
    {
      /* On classes and enums all attributes are ingrained.  */
      gcc_assert (attribs == TYPE_ATTRIBUTES (result));
      return result;
    }

  for (tree a = attribs; a; a = TREE_CHAIN (a))
    {
      const attribute_spec *as
	= lookup_attribute_spec (get_attribute_name (a));
      if (as && as->affects_type_identity)
	{
	  if (!first_ident)
	    first_ident = a;
	  else if (first_ident == error_mark_node)
	    {
	      *p = tree_cons (TREE_PURPOSE (a), TREE_VALUE (a), NULL_TREE);
	      p = &TREE_CHAIN (*p);
	    }
	}
      else if (first_ident && first_ident != error_mark_node)
	{
	  for (tree a2 = first_ident; a2 != a; a2 = TREE_CHAIN (a2))
	    {
	      *p = tree_cons (TREE_PURPOSE (a2), TREE_VALUE (a2), NULL_TREE);
	      p = &TREE_CHAIN (*p);
	    }
	  first_ident = error_mark_node;
	}
    }
  if (first_ident != error_mark_node)
    new_attribs = first_ident;

  if (first_ident == attribs)
    /* All attributes affected type identity.  */;
  else
    *remove_attributes = true;

  return cp_build_type_attribute_variant (result, new_attribs);
}

/* Builds a qualified variant of T that is either not a typedef variant
   (the default behavior) or not a typedef variant of a user-facing type
   (if FLAGS contains STF_USER_FACING).

   E.g. consider the following declarations:
     typedef const int ConstInt;
     typedef ConstInt* PtrConstInt;
   If T is PtrConstInt, this function returns a type representing
     const int*.
   In other words, if T is a typedef, the function returns the underlying type.
   The cv-qualification and attributes of the type returned match the
   input type.
   They will always be compatible types.
   The returned type is built so that all of its subtypes
   recursively have their typedefs stripped as well.

   This is different from just returning TYPE_CANONICAL (T)
   Because of several reasons:
    * If T is a type that needs structural equality
      its TYPE_CANONICAL (T) will be NULL.
    * TYPE_CANONICAL (T) desn't carry type attributes
      and loses template parameter names.

   If REMOVE_ATTRIBUTES is non-null, also strip attributes that don't
   affect type identity, and set the referent to true if any were
   stripped.  */

tree
strip_typedefs (tree t, bool *remove_attributes /* = NULL */,
		unsigned int flags /* = 0 */)
{
  tree result = NULL, type = NULL, t0 = NULL;

  if (!t || t == error_mark_node)
    return t;

  if (TREE_CODE (t) == TREE_LIST)
    {
      bool changed = false;
      releasing_vec vec;
      tree r = t;
      for (; t; t = TREE_CHAIN (t))
	{
	  gcc_assert (!TREE_PURPOSE (t));
	  tree elt = strip_typedefs (TREE_VALUE (t), remove_attributes, flags);
	  if (elt != TREE_VALUE (t))
	    changed = true;
	  vec_safe_push (vec, elt);
	}
      if (changed)
	r = build_tree_list_vec (vec);
      return r;
    }

  gcc_assert (TYPE_P (t));

  if (t == TYPE_CANONICAL (t))
    return t;

  if (!(flags & STF_STRIP_DEPENDENT)
      && dependent_alias_template_spec_p (t, nt_opaque))
    /* DR 1558: However, if the template-id is dependent, subsequent
       template argument substitution still applies to the template-id.  */
    return t;

  switch (TREE_CODE (t))
    {
    case POINTER_TYPE:
      type = strip_typedefs (TREE_TYPE (t), remove_attributes, flags);
      result = build_pointer_type_for_mode (type, TYPE_MODE (t), false);
      break;
    case REFERENCE_TYPE:
      type = strip_typedefs (TREE_TYPE (t), remove_attributes, flags);
      result = cp_build_reference_type_for_mode (type, TYPE_MODE (t), TYPE_REF_IS_RVALUE (t));
      break;
    case OFFSET_TYPE:
      t0 = strip_typedefs (TYPE_OFFSET_BASETYPE (t), remove_attributes, flags);
      type = strip_typedefs (TREE_TYPE (t), remove_attributes, flags);
      result = build_offset_type (t0, type);
      break;
    case RECORD_TYPE:
      if (TYPE_PTRMEMFUNC_P (t))
	{
	  t0 = strip_typedefs (TYPE_PTRMEMFUNC_FN_TYPE (t),
			       remove_attributes, flags);
	  result = build_ptrmemfunc_type (t0);
	}
      break;
    case ARRAY_TYPE:
      type = strip_typedefs (TREE_TYPE (t), remove_attributes, flags);
      t0  = strip_typedefs (TYPE_DOMAIN (t), remove_attributes, flags);
      gcc_checking_assert (TYPE_DEPENDENT_P_VALID (t)
			   || !dependent_type_p (t));
      result = build_cplus_array_type (type, t0, TYPE_DEPENDENT_P (t));
      break;
    case FUNCTION_TYPE:
    case METHOD_TYPE:
      {
	tree arg_types = NULL, arg_node, arg_node2, arg_type;
	bool changed;

	/* Because we stomp on TREE_PURPOSE of TYPE_ARG_TYPES in many places
	   around the compiler (e.g. cp_parser_late_parsing_default_args), we
	   can't expect that re-hashing a function type will find a previous
	   equivalent type, so try to reuse the input type if nothing has
	   changed.  If the type is itself a variant, that will change.  */
	bool is_variant = typedef_variant_p (t);
	if (remove_attributes
	    && (TYPE_ATTRIBUTES (t) || TYPE_USER_ALIGN (t)))
	  is_variant = true;

	type = strip_typedefs (TREE_TYPE (t), remove_attributes, flags);
	tree canon_spec = (flag_noexcept_type
			   ? canonical_eh_spec (TYPE_RAISES_EXCEPTIONS (t))
			   : NULL_TREE);
	changed = (type != TREE_TYPE (t) || is_variant
		   || TYPE_RAISES_EXCEPTIONS (t) != canon_spec);

	for (arg_node = TYPE_ARG_TYPES (t);
	     arg_node;
	     arg_node = TREE_CHAIN (arg_node))
	  {
	    if (arg_node == void_list_node)
	      break;
	    arg_type = strip_typedefs (TREE_VALUE (arg_node),
				       remove_attributes, flags);
	    gcc_assert (arg_type);
	    if (arg_type == TREE_VALUE (arg_node) && !changed)
	      continue;

	    if (!changed)
	      {
		changed = true;
		for (arg_node2 = TYPE_ARG_TYPES (t);
		     arg_node2 != arg_node;
		     arg_node2 = TREE_CHAIN (arg_node2))
		  arg_types
		    = tree_cons (TREE_PURPOSE (arg_node2),
				 TREE_VALUE (arg_node2), arg_types);
	      }

	    arg_types
	      = tree_cons (TREE_PURPOSE (arg_node), arg_type, arg_types);
	  }

	if (!changed)
	  return t;

	if (arg_types)
	  arg_types = nreverse (arg_types);

	/* A list of parameters not ending with an ellipsis
	   must end with void_list_node.  */
	if (arg_node)
	  arg_types = chainon (arg_types, void_list_node);

	if (TREE_CODE (t) == METHOD_TYPE)
	  {
	    tree class_type = TREE_TYPE (TREE_VALUE (arg_types));
	    gcc_assert (class_type);
	    result =
	      build_method_type_directly (class_type, type,
					  TREE_CHAIN (arg_types));
	  }
	else
	  {
	    result = build_function_type (type, arg_types);
	    result = apply_memfn_quals (result, type_memfn_quals (t));
	  }

	result = build_cp_fntype_variant (result,
					  type_memfn_rqual (t), canon_spec,
					  TYPE_HAS_LATE_RETURN_TYPE (t));
      }
      break;
    case TYPENAME_TYPE:
      {
	bool changed = false;
	tree fullname = TYPENAME_TYPE_FULLNAME (t);
	if (TREE_CODE (fullname) == TEMPLATE_ID_EXPR
	    && TREE_OPERAND (fullname, 1))
	  {
	    tree args = TREE_OPERAND (fullname, 1);
	    tree new_args = copy_node (args);
	    for (int i = 0; i < TREE_VEC_LENGTH (args); ++i)
	      {
		tree arg = TREE_VEC_ELT (args, i);
		tree strip_arg;
		if (TYPE_P (arg))
		  strip_arg = strip_typedefs (arg, remove_attributes, flags);
		else
		  strip_arg = strip_typedefs_expr (arg, remove_attributes,
						   flags);
		TREE_VEC_ELT (new_args, i) = strip_arg;
		if (strip_arg != arg)
		  changed = true;
	      }
	    if (changed)
	      {
		NON_DEFAULT_TEMPLATE_ARGS_COUNT (new_args)
		  = NON_DEFAULT_TEMPLATE_ARGS_COUNT (args);
		fullname
		  = lookup_template_function (TREE_OPERAND (fullname, 0),
					      new_args);
	      }
	    else
	      ggc_free (new_args);
	  }
	tree ctx = strip_typedefs (TYPE_CONTEXT (t), remove_attributes, flags);
	if (!changed && ctx == TYPE_CONTEXT (t) && !typedef_variant_p (t))
	  return t;
	tree name = fullname;
	if (TREE_CODE (fullname) == TEMPLATE_ID_EXPR)
	  name = TREE_OPERAND (fullname, 0);
	/* Use build_typename_type rather than make_typename_type because we
	   don't want to resolve it here, just strip typedefs.  */
	result = build_typename_type (ctx, name, fullname, typename_type);
      }
      break;
    case DECLTYPE_TYPE:
      result = strip_typedefs_expr (DECLTYPE_TYPE_EXPR (t),
				    remove_attributes, flags);
      if (result == DECLTYPE_TYPE_EXPR (t))
	result = NULL_TREE;
      else
	result = (finish_decltype_type
		  (result,
		   DECLTYPE_TYPE_ID_EXPR_OR_MEMBER_ACCESS_P (t),
		   tf_none));
      break;
    case UNDERLYING_TYPE:
      type = strip_typedefs (UNDERLYING_TYPE_TYPE (t),
			     remove_attributes, flags);
      result = finish_underlying_type (type);
      break;
    case TYPE_PACK_EXPANSION:
      {
	tree pat = PACK_EXPANSION_PATTERN (t);
	if (TYPE_P (pat))
	  {
	    type = strip_typedefs (pat, remove_attributes, flags);
	    if (type != pat)
	      {
		result = build_distinct_type_copy (t);
		PACK_EXPANSION_PATTERN (result) = type;
	      }
	  }
      }
      break;
    default:
      break;
    }

  if (!result)
    {
      if (typedef_variant_p (t))
	{
	  if ((flags & STF_USER_VISIBLE)
	      && !user_facing_original_type_p (t))
	    return t;
	  /* If T is a non-template alias or typedef, we can assume that
	     instantiating its definition will hit any substitution failure,
	     so we don't need to retain it here as well.  */
	  if (!alias_template_specialization_p (t, nt_opaque))
	    flags |= STF_STRIP_DEPENDENT;
	  result = strip_typedefs (DECL_ORIGINAL_TYPE (TYPE_NAME (t)),
				   remove_attributes, flags);
	}
      else
	result = TYPE_MAIN_VARIANT (t);
    }
  /*gcc_assert (!typedef_variant_p (result)
	      || dependent_alias_template_spec_p (result, nt_opaque)
	      || ((flags & STF_USER_VISIBLE)
		  && !user_facing_original_type_p (result)));*/

  if (COMPLETE_TYPE_P (result) && !COMPLETE_TYPE_P (t))
  /* If RESULT is complete and T isn't, it's likely the case that T
     is a variant of RESULT which hasn't been updated yet.  Skip the
     attribute handling.  */;
  else
    {
      if (TYPE_USER_ALIGN (t) != TYPE_USER_ALIGN (result)
	  || TYPE_ALIGN (t) != TYPE_ALIGN (result))
	{
	  gcc_assert (TYPE_USER_ALIGN (t));
	  if (remove_attributes)
	    *remove_attributes = true;
	  else
	    {
	      if (TYPE_ALIGN (t) == TYPE_ALIGN (result))
		result = build_variant_type_copy (result);
	      else
		result = build_aligned_type (result, TYPE_ALIGN (t));
	      TYPE_USER_ALIGN (result) = true;
	    }
	}

      if (TYPE_ATTRIBUTES (t))
	{
	  if (remove_attributes)
	    result = apply_identity_attributes (result, TYPE_ATTRIBUTES (t),
						remove_attributes);
	  else
	    result = cp_build_type_attribute_variant (result,
						      TYPE_ATTRIBUTES (t));
	}
    }

  return cp_build_qualified_type (result, cp_type_quals (t));
}

/* Like strip_typedefs above, but works on expressions, so that in

   template<class T> struct A
   {
     typedef T TT;
     B<sizeof(TT)> b;
   };

   sizeof(TT) is replaced by sizeof(T).  */

tree
strip_typedefs_expr (tree t, bool *remove_attributes, unsigned int flags)
{
  unsigned i,n;
  tree r, type, *ops;
  enum tree_code code;

  if (t == NULL_TREE || t == error_mark_node)
    return t;

  STRIP_ANY_LOCATION_WRAPPER (t);

  if (DECL_P (t) || CONSTANT_CLASS_P (t))
    return t;

  /* Some expressions have type operands, so let's handle types here rather
     than check TYPE_P in multiple places below.  */
  if (TYPE_P (t))
    return strip_typedefs (t, remove_attributes, flags);

  code = TREE_CODE (t);
  switch (code)
    {
    case IDENTIFIER_NODE:
    case TEMPLATE_PARM_INDEX:
    case OVERLOAD:
    case BASELINK:
    case ARGUMENT_PACK_SELECT:
      return t;

    case TRAIT_EXPR:
      {
	tree type1 = strip_typedefs (TRAIT_EXPR_TYPE1 (t),
				     remove_attributes, flags);
	tree type2 = strip_typedefs (TRAIT_EXPR_TYPE2 (t),
				     remove_attributes, flags);
	if (type1 == TRAIT_EXPR_TYPE1 (t)
	    && type2 == TRAIT_EXPR_TYPE2 (t))
	  return t;
	r = copy_node (t);
	TRAIT_EXPR_TYPE1 (r) = type1;
	TRAIT_EXPR_TYPE2 (r) = type2;
	return r;
      }

    case TREE_LIST:
      {
	releasing_vec vec;
	bool changed = false;
	tree it;
	for (it = t; it; it = TREE_CHAIN (it))
	  {
	    tree val = strip_typedefs_expr (TREE_VALUE (it),
					    remove_attributes, flags);
	    vec_safe_push (vec, val);
	    if (val != TREE_VALUE (it))
	      changed = true;
	    gcc_assert (TREE_PURPOSE (it) == NULL_TREE);
	  }
	if (changed)
	  {
	    r = NULL_TREE;
	    FOR_EACH_VEC_ELT_REVERSE (*vec, i, it)
	      r = tree_cons (NULL_TREE, it, r);
	  }
	else
	  r = t;
	return r;
      }

    case TREE_VEC:
      {
	bool changed = false;
	releasing_vec vec;
	n = TREE_VEC_LENGTH (t);
	vec_safe_reserve (vec, n);
	for (i = 0; i < n; ++i)
	  {
	    tree op = strip_typedefs_expr (TREE_VEC_ELT (t, i),
					   remove_attributes, flags);
	    vec->quick_push (op);
	    if (op != TREE_VEC_ELT (t, i))
	      changed = true;
	  }
	if (changed)
	  {
	    r = copy_node (t);
	    for (i = 0; i < n; ++i)
	      TREE_VEC_ELT (r, i) = (*vec)[i];
	    NON_DEFAULT_TEMPLATE_ARGS_COUNT (r)
	      = NON_DEFAULT_TEMPLATE_ARGS_COUNT (t);
	  }
	else
	  r = t;
	return r;
      }

    case CONSTRUCTOR:
      {
	bool changed = false;
	vec<constructor_elt, va_gc> *vec
	  = vec_safe_copy (CONSTRUCTOR_ELTS (t));
	n = CONSTRUCTOR_NELTS (t);
	type = strip_typedefs (TREE_TYPE (t), remove_attributes, flags);
	for (i = 0; i < n; ++i)
	  {
	    constructor_elt *e = &(*vec)[i];
	    tree op = strip_typedefs_expr (e->value, remove_attributes, flags);
	    if (op != e->value)
	      {
		changed = true;
		e->value = op;
	      }
	    gcc_checking_assert
	      (e->index == strip_typedefs_expr (e->index, remove_attributes,
						flags));
	  }

	if (!changed && type == TREE_TYPE (t))
	  {
	    vec_free (vec);
	    return t;
	  }
	else
	  {
	    r = copy_node (t);
	    TREE_TYPE (r) = type;
	    CONSTRUCTOR_ELTS (r) = vec;
	    return r;
	  }
      }

    case LAMBDA_EXPR:
      return t;

    case STATEMENT_LIST:
      error ("statement-expression in a constant expression");
      return error_mark_node;

    default:
      break;
    }

  gcc_assert (EXPR_P (t));

  n = cp_tree_operand_length (t);
  ops = XALLOCAVEC (tree, n);
  type = TREE_TYPE (t);

  switch (code)
    {
    CASE_CONVERT:
    case IMPLICIT_CONV_EXPR:
    case DYNAMIC_CAST_EXPR:
    case STATIC_CAST_EXPR:
    case CONST_CAST_EXPR:
    case REINTERPRET_CAST_EXPR:
    case CAST_EXPR:
    case NEW_EXPR:
      type = strip_typedefs (type, remove_attributes, flags);
      /* fallthrough */

    default:
      for (i = 0; i < n; ++i)
	ops[i] = strip_typedefs_expr (TREE_OPERAND (t, i),
				      remove_attributes, flags);
      break;
    }

  /* If nothing changed, return t.  */
  for (i = 0; i < n; ++i)
    if (ops[i] != TREE_OPERAND (t, i))
      break;
  if (i == n && type == TREE_TYPE (t))
    return t;

  r = copy_node (t);
  TREE_TYPE (r) = type;
  for (i = 0; i < n; ++i)
    TREE_OPERAND (r, i) = ops[i];
  return r;
}

/* Makes a copy of BINFO and TYPE, which is to be inherited into a
   graph dominated by T.  If BINFO is NULL, TYPE is a dependent base,
   and we do a shallow copy.  If BINFO is non-NULL, we do a deep copy.
   VIRT indicates whether TYPE is inherited virtually or not.
   IGO_PREV points at the previous binfo of the inheritance graph
   order chain.  The newly copied binfo's TREE_CHAIN forms this
   ordering.

   The CLASSTYPE_VBASECLASSES vector of T is constructed in the
   correct order. That is in the order the bases themselves should be
   constructed in.

   The BINFO_INHERITANCE of a virtual base class points to the binfo
   of the most derived type. ??? We could probably change this so that
   BINFO_INHERITANCE becomes synonymous with BINFO_PRIMARY, and hence
   remove a field.  They currently can only differ for primary virtual
   virtual bases.  */

tree
copy_binfo (tree binfo, tree type, tree t, tree *igo_prev, int virt)
{
  tree new_binfo;

  if (virt)
    {
      /* See if we've already made this virtual base.  */
      new_binfo = binfo_for_vbase (type, t);
      if (new_binfo)
	return new_binfo;
    }

  new_binfo = make_tree_binfo (binfo ? BINFO_N_BASE_BINFOS (binfo) : 0);
  BINFO_TYPE (new_binfo) = type;

  /* Chain it into the inheritance graph.  */
  TREE_CHAIN (*igo_prev) = new_binfo;
  *igo_prev = new_binfo;

  if (binfo && !BINFO_DEPENDENT_BASE_P (binfo))
    {
      int ix;
      tree base_binfo;

      gcc_assert (SAME_BINFO_TYPE_P (BINFO_TYPE (binfo), type));

      BINFO_OFFSET (new_binfo) = BINFO_OFFSET (binfo);
      BINFO_VIRTUALS (new_binfo) = BINFO_VIRTUALS (binfo);

      /* We do not need to copy the accesses, as they are read only.  */
      BINFO_BASE_ACCESSES (new_binfo) = BINFO_BASE_ACCESSES (binfo);

      /* Recursively copy base binfos of BINFO.  */
      for (ix = 0; BINFO_BASE_ITERATE (binfo, ix, base_binfo); ix++)
	{
	  tree new_base_binfo;
	  new_base_binfo = copy_binfo (base_binfo, BINFO_TYPE (base_binfo),
				       t, igo_prev,
				       BINFO_VIRTUAL_P (base_binfo));

	  if (!BINFO_INHERITANCE_CHAIN (new_base_binfo))
	    BINFO_INHERITANCE_CHAIN (new_base_binfo) = new_binfo;
	  BINFO_BASE_APPEND (new_binfo, new_base_binfo);
	}
    }
  else
    BINFO_DEPENDENT_BASE_P (new_binfo) = 1;

  if (virt)
    {
      /* Push it onto the list after any virtual bases it contains
	 will have been pushed.  */
      CLASSTYPE_VBASECLASSES (t)->quick_push (new_binfo);
      BINFO_VIRTUAL_P (new_binfo) = 1;
      BINFO_INHERITANCE_CHAIN (new_binfo) = TYPE_BINFO (t);
    }

  return new_binfo;
}

/* Hashing of lists so that we don't make duplicates.
   The entry point is `list_hash_canon'.  */

struct list_proxy
{
  tree purpose;
  tree value;
  tree chain;
};

struct list_hasher : ggc_ptr_hash<tree_node>
{
  typedef list_proxy *compare_type;

  static hashval_t hash (tree);
  static bool equal (tree, list_proxy *);
};

/* Now here is the hash table.  When recording a list, it is added
   to the slot whose index is the hash code mod the table size.
   Note that the hash table is used for several kinds of lists.
   While all these live in the same table, they are completely independent,
   and the hash code is computed differently for each of these.  */

static GTY (()) hash_table<list_hasher> *list_hash_table;

/* Compare ENTRY (an entry in the hash table) with DATA (a list_proxy
   for a node we are thinking about adding).  */

bool
list_hasher::equal (tree t, list_proxy *proxy)
{
  return (TREE_VALUE (t) == proxy->value
	  && TREE_PURPOSE (t) == proxy->purpose
	  && TREE_CHAIN (t) == proxy->chain);
}

/* Compute a hash code for a list (chain of TREE_LIST nodes
   with goodies in the TREE_PURPOSE, TREE_VALUE, and bits of the
   TREE_COMMON slots), by adding the hash codes of the individual entries.  */

static hashval_t
list_hash_pieces (tree purpose, tree value, tree chain)
{
  hashval_t hashcode = 0;

  if (chain)
    hashcode += TREE_HASH (chain);

  if (value)
    hashcode += TREE_HASH (value);
  else
    hashcode += 1007;
  if (purpose)
    hashcode += TREE_HASH (purpose);
  else
    hashcode += 1009;
  return hashcode;
}

/* Hash an already existing TREE_LIST.  */

hashval_t
list_hasher::hash (tree t)
{
  return list_hash_pieces (TREE_PURPOSE (t),
			   TREE_VALUE (t),
			   TREE_CHAIN (t));
}

/* Given list components PURPOSE, VALUE, AND CHAIN, return the canonical
   object for an identical list if one already exists.  Otherwise, build a
   new one, and record it as the canonical object.  */

tree
hash_tree_cons (tree purpose, tree value, tree chain)
{
  int hashcode = 0;
  tree *slot;
  struct list_proxy proxy;

  /* Hash the list node.  */
  hashcode = list_hash_pieces (purpose, value, chain);
  /* Create a proxy for the TREE_LIST we would like to create.  We
     don't actually create it so as to avoid creating garbage.  */
  proxy.purpose = purpose;
  proxy.value = value;
  proxy.chain = chain;
  /* See if it is already in the table.  */
  slot = list_hash_table->find_slot_with_hash (&proxy, hashcode, INSERT);
  /* If not, create a new node.  */
  if (!*slot)
    *slot = tree_cons (purpose, value, chain);
  return (tree) *slot;
}

/* Constructor for hashed lists.  */

tree
hash_tree_chain (tree value, tree chain)
{
  return hash_tree_cons (NULL_TREE, value, chain);
}

void
debug_binfo (tree elem)
{
  HOST_WIDE_INT n;
  tree virtuals;

  fprintf (stderr, "type \"%s\", offset = " HOST_WIDE_INT_PRINT_DEC
	   "\nvtable type:\n",
	   TYPE_NAME_STRING (BINFO_TYPE (elem)),
	   TREE_INT_CST_LOW (BINFO_OFFSET (elem)));
  debug_tree (BINFO_TYPE (elem));
  if (BINFO_VTABLE (elem))
    fprintf (stderr, "vtable decl \"%s\"\n",
	     IDENTIFIER_POINTER (DECL_NAME (get_vtbl_decl_for_binfo (elem))));
  else
    fprintf (stderr, "no vtable decl yet\n");
  fprintf (stderr, "virtuals:\n");
  virtuals = BINFO_VIRTUALS (elem);
  n = 0;

  while (virtuals)
    {
      tree fndecl = TREE_VALUE (virtuals);
      fprintf (stderr, "%s [%ld =? %ld]\n",
	       IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (fndecl)),
	       (long) n, (long) TREE_INT_CST_LOW (DECL_VINDEX (fndecl)));
      ++n;
      virtuals = TREE_CHAIN (virtuals);
    }
}

/* Build a representation for the qualified name SCOPE::NAME.  TYPE is
   the type of the result expression, if known, or NULL_TREE if the
   resulting expression is type-dependent.  If TEMPLATE_P is true,
   NAME is known to be a template because the user explicitly used the
   "template" keyword after the "::".

   All SCOPE_REFs should be built by use of this function.  */

tree
build_qualified_name (tree type, tree scope, tree name, bool template_p)
{
  tree t;
  if (type == error_mark_node
      || scope == error_mark_node
      || name == error_mark_node)
    return error_mark_node;
  gcc_assert (TREE_CODE (name) != SCOPE_REF);
  t = build2 (SCOPE_REF, type, scope, name);
  QUALIFIED_NAME_IS_TEMPLATE (t) = template_p;
  PTRMEM_OK_P (t) = true;
  if (type)
    t = convert_from_reference (t);
  return t;
}

/* Like check_qualified_type, but also check ref-qualifier, exception
   specification, and whether the return type was specified after the
   parameters.  */

static bool
cp_check_qualified_type (const_tree cand, const_tree base, int type_quals,
			 cp_ref_qualifier rqual, tree raises, bool late)
{
  return (TYPE_QUALS (cand) == type_quals
	  && check_base_type (cand, base)
	  && comp_except_specs (raises, TYPE_RAISES_EXCEPTIONS (cand),
				ce_exact)
	  && TYPE_HAS_LATE_RETURN_TYPE (cand) == late
	  && type_memfn_rqual (cand) == rqual);
}

/* Build the FUNCTION_TYPE or METHOD_TYPE with the ref-qualifier RQUAL.  */

tree
build_ref_qualified_type (tree type, cp_ref_qualifier rqual)
{
  tree raises = TYPE_RAISES_EXCEPTIONS (type);
  bool late = TYPE_HAS_LATE_RETURN_TYPE (type);
  return build_cp_fntype_variant (type, rqual, raises, late);
}

tree
make_binding_vec (tree name, unsigned clusters MEM_STAT_DECL)
{
  /* Stored in an unsigned short, but we're limited to the number of
     modules anyway.  */
  gcc_checking_assert (clusters <= (unsigned short)(~0));
  size_t length = (offsetof (tree_binding_vec, vec)
		   + clusters * sizeof (binding_cluster));
  tree vec = ggc_alloc_cleared_tree_node_stat (length PASS_MEM_STAT);
  TREE_SET_CODE (vec, BINDING_VECTOR);
  BINDING_VECTOR_NAME (vec) = name;
  BINDING_VECTOR_ALLOC_CLUSTERS (vec) = clusters;
  BINDING_VECTOR_NUM_CLUSTERS (vec) = 0;

  return vec;
}

/* Make a raw overload node containing FN.  */

tree
ovl_make (tree fn, tree next)
{
  tree result = make_node (OVERLOAD);

  if (TREE_CODE (fn) == OVERLOAD)
    OVL_NESTED_P (result) = true;

  TREE_TYPE (result) = (next || TREE_CODE (fn) == TEMPLATE_DECL
			? unknown_type_node : TREE_TYPE (fn));
  if (next && TREE_CODE (next) == OVERLOAD && OVL_DEDUP_P (next))
    OVL_DEDUP_P (result) = true;
  OVL_FUNCTION (result) = fn;
  OVL_CHAIN (result) = next;
  return result;
}

/* Add FN to the (potentially NULL) overload set OVL.  USING_OR_HIDDEN is >
   zero if this is a using-decl.  It is > 1 if we're exporting the
   using decl.  USING_OR_HIDDEN is < 0, if FN is hidden.  (A decl
   cannot be both using and hidden.)  We keep the hidden decls first,
   but remaining ones are unordered.  */

tree
ovl_insert (tree fn, tree maybe_ovl, int using_or_hidden)
{
  tree result = maybe_ovl;
  tree insert_after = NULL_TREE;

  /* Skip hidden.  */
  for (; maybe_ovl && TREE_CODE (maybe_ovl) == OVERLOAD
	 && OVL_HIDDEN_P (maybe_ovl);
       maybe_ovl = OVL_CHAIN (maybe_ovl))
    {
      gcc_checking_assert (!OVL_LOOKUP_P (maybe_ovl));
      insert_after = maybe_ovl;
    }

  if (maybe_ovl || using_or_hidden || TREE_CODE (fn) == TEMPLATE_DECL)
    {
      maybe_ovl = ovl_make (fn, maybe_ovl);

      if (using_or_hidden < 0)
	OVL_HIDDEN_P (maybe_ovl) = true;
      if (using_or_hidden > 0)
	{
	  OVL_DEDUP_P (maybe_ovl) = OVL_USING_P (maybe_ovl) = true;
	  if (using_or_hidden > 1)
	    OVL_EXPORT_P (maybe_ovl) = true;
	}
    }
  else
    maybe_ovl = fn;

  if (insert_after)
    {
      OVL_CHAIN (insert_after) = maybe_ovl;
      TREE_TYPE (insert_after) = unknown_type_node;
    }
  else
    result = maybe_ovl;

  return result;
}

/* Skip any hidden names at the beginning of OVL.   */

tree
ovl_skip_hidden (tree ovl)
{
  while (ovl && TREE_CODE (ovl) == OVERLOAD && OVL_HIDDEN_P (ovl))
    ovl = OVL_CHAIN (ovl);

  return ovl;
}

/* NODE is an OVL_HIDDEN_P node that is now revealed.  */

tree
ovl_iterator::reveal_node (tree overload, tree node)
{
  /* We cannot have returned NODE as part of a lookup overload, so we
     don't have to worry about preserving that.  */

  OVL_HIDDEN_P (node) = false;
  if (tree chain = OVL_CHAIN (node))
    if (TREE_CODE (chain) == OVERLOAD)
      {
	if (OVL_HIDDEN_P (chain))
	  {
	    /* The node needs moving, and the simplest way is to remove it
	       and reinsert.  */
	    overload = remove_node (overload, node);
	    overload = ovl_insert (OVL_FUNCTION (node), overload);
	  }
	else if (OVL_DEDUP_P (chain))
	  OVL_DEDUP_P (node) = true;
      }
  return overload;
}

/* NODE is on the overloads of OVL.  Remove it.  
   The removed node is unaltered and may continue to be iterated
   from (i.e. it is safe to remove a node from an overload one is
   currently iterating over).  */

tree
ovl_iterator::remove_node (tree overload, tree node)
{
  tree *slot = &overload;
  while (*slot != node)
    {
      tree probe = *slot;
      gcc_checking_assert (!OVL_LOOKUP_P (probe));

      slot = &OVL_CHAIN (probe);
    }

  /* Stitch out NODE.  We don't have to worry about now making a
     singleton overload (and consequently maybe setting its type),
     because all uses of this function will be followed by inserting a
     new node that must follow the place we've cut this out from.  */
  if (TREE_CODE (node) != OVERLOAD)
    /* Cloned inherited ctors don't mark themselves as via_using.  */
    *slot = NULL_TREE;
  else
    *slot = OVL_CHAIN (node);

  return overload;
}

/* Mark or unmark a lookup set. */

void
lookup_mark (tree ovl, bool val)
{
  for (lkp_iterator iter (ovl); iter; ++iter)
    {
      gcc_checking_assert (LOOKUP_SEEN_P (*iter) != val);
      LOOKUP_SEEN_P (*iter) = val;
    }
}

/* Add a set of new FNS into a lookup.  */

tree
lookup_add (tree fns, tree lookup)
{
  if (fns == error_mark_node || lookup == error_mark_node)
    return error_mark_node;

  if (lookup || TREE_CODE (fns) == TEMPLATE_DECL)
    {
      lookup = ovl_make (fns, lookup);
      OVL_LOOKUP_P (lookup) = true;
    }
  else
    lookup = fns;

  return lookup;
}

/* FNS is a new overload set, add them to LOOKUP, if they are not
   already present there.  */

tree
lookup_maybe_add (tree fns, tree lookup, bool deduping)
{
  if (deduping)
    for (tree next, probe = fns; probe; probe = next)
      {
	tree fn = probe;
	next = NULL_TREE;

	if (TREE_CODE (probe) == OVERLOAD)
	  {
	    fn = OVL_FUNCTION (probe);
	    next = OVL_CHAIN (probe);
	  }

	if (!LOOKUP_SEEN_P (fn))
	  LOOKUP_SEEN_P (fn) = true;
	else
	  {
	    /* This function was already seen.  Insert all the
	       predecessors onto the lookup.  */
	    for (; fns != probe; fns = OVL_CHAIN (fns))
	      {
		lookup = lookup_add (OVL_FUNCTION (fns), lookup);
		/* Propagate OVL_USING, but OVL_HIDDEN &
		   OVL_DEDUP_P don't matter.  */
		if (OVL_USING_P (fns))
		  OVL_USING_P (lookup) = true;
	      }

	    /* And now skip this function.  */
	    fns = next;
	  }
      }

  if (fns)
    /* We ended in a set of new functions.  Add them all in one go.  */
    lookup = lookup_add (fns, lookup);

  return lookup;
}

/* Returns nonzero if X is an expression for a (possibly overloaded)
   function.  If "f" is a function or function template, "f", "c->f",
   "c.f", "C::f", and "f<int>" will all be considered possibly
   overloaded functions.  Returns 2 if the function is actually
   overloaded, i.e., if it is impossible to know the type of the
   function without performing overload resolution.  */
 
int
is_overloaded_fn (tree x)
{
  STRIP_ANY_LOCATION_WRAPPER (x);

  /* A baselink is also considered an overloaded function.  */
  if (TREE_CODE (x) == OFFSET_REF
      || TREE_CODE (x) == COMPONENT_REF)
    x = TREE_OPERAND (x, 1);
  x = MAYBE_BASELINK_FUNCTIONS (x);
  if (TREE_CODE (x) == TEMPLATE_ID_EXPR)
    x = TREE_OPERAND (x, 0);

  if (DECL_FUNCTION_TEMPLATE_P (OVL_FIRST (x))
      || (TREE_CODE (x) == OVERLOAD && !OVL_SINGLE_P (x)))
    return 2;

  return OVL_P (x);
}

/* X is the CALL_EXPR_FN of a CALL_EXPR.  If X represents a dependent name
   (14.6.2), return the IDENTIFIER_NODE for that name.  Otherwise, return
   NULL_TREE.  */

tree
dependent_name (tree x)
{
  /* FIXME a dependent name must be unqualified, but this function doesn't
     distinguish between qualified and unqualified identifiers.  */
  if (identifier_p (x))
    return x;
  if (TREE_CODE (x) == TEMPLATE_ID_EXPR)
    x = TREE_OPERAND (x, 0);
  if (OVL_P (x))
    return OVL_NAME (x);
  return NULL_TREE;
}

/* Returns true iff X is an expression for an overloaded function
   whose type cannot be known without performing overload
   resolution.  */

bool
really_overloaded_fn (tree x)
{
  return is_overloaded_fn (x) == 2;
}

/* Get the overload set FROM refers to.  Returns NULL if it's not an
   overload set.  */

tree
maybe_get_fns (tree from)
{
  STRIP_ANY_LOCATION_WRAPPER (from);

  /* A baselink is also considered an overloaded function.  */
  if (TREE_CODE (from) == OFFSET_REF
      || TREE_CODE (from) == COMPONENT_REF)
    from = TREE_OPERAND (from, 1);
  if (BASELINK_P (from))
    from = BASELINK_FUNCTIONS (from);
  if (TREE_CODE (from) == TEMPLATE_ID_EXPR)
    from = TREE_OPERAND (from, 0);

  if (OVL_P (from))
    return from;

  return NULL;
}

/* FROM refers to an overload set.  Return that set (or die).  */

tree
get_fns (tree from)
{
  tree res = maybe_get_fns (from);

  gcc_assert (res);
  return res;
}

/* Return the first function of the overload set FROM refers to.  */

tree
get_first_fn (tree from)
{
  return OVL_FIRST (get_fns (from));
}

/* Return the scope where the overloaded functions OVL were found.  */

tree
ovl_scope (tree ovl)
{
  if (TREE_CODE (ovl) == OFFSET_REF
      || TREE_CODE (ovl) == COMPONENT_REF)
    ovl = TREE_OPERAND (ovl, 1);
  if (TREE_CODE (ovl) == BASELINK)
    return BINFO_TYPE (BASELINK_BINFO (ovl));
  if (TREE_CODE (ovl) == TEMPLATE_ID_EXPR)
    ovl = TREE_OPERAND (ovl, 0);
  /* Skip using-declarations.  */
  lkp_iterator iter (ovl);
  do
    ovl = *iter;
  while (iter.using_p () && ++iter);

  return CP_DECL_CONTEXT (ovl);
}

#define PRINT_RING_SIZE 4

static const char *
cxx_printable_name_internal (tree decl, int v, bool translate)
{
  static unsigned int uid_ring[PRINT_RING_SIZE];
  static char *print_ring[PRINT_RING_SIZE];
  static bool trans_ring[PRINT_RING_SIZE];
  static int ring_counter;
  int i;

  /* Only cache functions.  */
  if (v < 2
      || TREE_CODE (decl) != FUNCTION_DECL
      || DECL_LANG_SPECIFIC (decl) == 0)
    return lang_decl_name (decl, v, translate);

  /* See if this print name is lying around.  */
  for (i = 0; i < PRINT_RING_SIZE; i++)
    if (uid_ring[i] == DECL_UID (decl) && translate == trans_ring[i])
      /* yes, so return it.  */
      return print_ring[i];

  if (++ring_counter == PRINT_RING_SIZE)
    ring_counter = 0;

  if (current_function_decl != NULL_TREE)
    {
      /* There may be both translated and untranslated versions of the
	 name cached.  */
      for (i = 0; i < 2; i++)
	{
	  if (uid_ring[ring_counter] == DECL_UID (current_function_decl))
	    ring_counter += 1;
	  if (ring_counter == PRINT_RING_SIZE)
	    ring_counter = 0;
	}
      gcc_assert (uid_ring[ring_counter] != DECL_UID (current_function_decl));
    }

  free (print_ring[ring_counter]);

  print_ring[ring_counter] = xstrdup (lang_decl_name (decl, v, translate));
  uid_ring[ring_counter] = DECL_UID (decl);
  trans_ring[ring_counter] = translate;
  return print_ring[ring_counter];
}

const char *
cxx_printable_name (tree decl, int v)
{
  return cxx_printable_name_internal (decl, v, false);
}

const char *
cxx_printable_name_translate (tree decl, int v)
{
  return cxx_printable_name_internal (decl, v, true);
}

/* Return the canonical version of exception-specification RAISES for a C++17
   function type, for use in type comparison and building TYPE_CANONICAL.  */

tree
canonical_eh_spec (tree raises)
{
  if (raises == NULL_TREE)
    return raises;
  else if (DEFERRED_NOEXCEPT_SPEC_P (raises)
	   || UNPARSED_NOEXCEPT_SPEC_P (raises)
	   || uses_template_parms (raises)
	   || uses_template_parms (TREE_PURPOSE (raises)))
    /* Keep a dependent or deferred exception specification.  */
    return raises;
  else if (nothrow_spec_p (raises))
    /* throw() -> noexcept.  */
    return noexcept_true_spec;
  else
    /* For C++17 type matching, anything else -> nothing.  */
    return NULL_TREE;
}

tree
build_cp_fntype_variant (tree type, cp_ref_qualifier rqual,
			 tree raises, bool late)
{
  cp_cv_quals type_quals = TYPE_QUALS (type);

  if (cp_check_qualified_type (type, type, type_quals, rqual, raises, late))
    return type;

  tree v = TYPE_MAIN_VARIANT (type);
  for (; v; v = TYPE_NEXT_VARIANT (v))
    if (cp_check_qualified_type (v, type, type_quals, rqual, raises, late))
      return v;

  /* Need to build a new variant.  */
  v = build_variant_type_copy (type);
  if (!TYPE_DEPENDENT_P (v))
    /* We no longer know that it's not type-dependent.  */
    TYPE_DEPENDENT_P_VALID (v) = false;
  TYPE_RAISES_EXCEPTIONS (v) = raises;
  TYPE_HAS_LATE_RETURN_TYPE (v) = late;
  switch (rqual)
    {
    case REF_QUAL_RVALUE:
      FUNCTION_RVALUE_QUALIFIED (v) = 1;
      FUNCTION_REF_QUALIFIED (v) = 1;
      break;
    case REF_QUAL_LVALUE:
      FUNCTION_RVALUE_QUALIFIED (v) = 0;
      FUNCTION_REF_QUALIFIED (v) = 1;
      break;
    default:
      FUNCTION_REF_QUALIFIED (v) = 0;
      break;
    }

  /* Canonicalize the exception specification.  */
  tree cr = flag_noexcept_type ? canonical_eh_spec (raises) : NULL_TREE;

  if (TYPE_STRUCTURAL_EQUALITY_P (type))
    /* Propagate structural equality. */
    SET_TYPE_STRUCTURAL_EQUALITY (v);
  else if (TYPE_CANONICAL (type) != type || cr != raises || late)
    /* Build the underlying canonical type, since it is different
       from TYPE. */
    TYPE_CANONICAL (v) = build_cp_fntype_variant (TYPE_CANONICAL (type),
						  rqual, cr, false);
  else
    /* T is its own canonical type. */
    TYPE_CANONICAL (v) = v;

  return v;
}

/* TYPE is a function or method type with a deferred exception
   specification that has been parsed to RAISES.  Fixup all the type
   variants that are affected in place.  Via decltype &| noexcept
   tricks, the unparsed spec could have escaped into the type system.
   The general case is hard to fixup canonical types for.  */

void
fixup_deferred_exception_variants (tree type, tree raises)
{
  tree original = TYPE_RAISES_EXCEPTIONS (type);
  tree cr = flag_noexcept_type ? canonical_eh_spec (raises) : NULL_TREE;

  gcc_checking_assert (UNPARSED_NOEXCEPT_SPEC_P (original));

  /* Though sucky, this walk will process the canonical variants
     first.  */
  tree prev = NULL_TREE;
  for (tree variant = TYPE_MAIN_VARIANT (type);
       variant; prev = variant, variant = TYPE_NEXT_VARIANT (variant))
    if (TYPE_RAISES_EXCEPTIONS (variant) == original)
      {
	gcc_checking_assert (variant != TYPE_MAIN_VARIANT (type));

	if (!TYPE_STRUCTURAL_EQUALITY_P (variant))
	  {
	    cp_cv_quals var_quals = TYPE_QUALS (variant);
	    cp_ref_qualifier rqual = type_memfn_rqual (variant);

	    /* If VARIANT would become a dup (cp_check_qualified_type-wise)
	       of an existing variant in the variant list of TYPE after its
	       exception specification has been parsed, elide it.  Otherwise,
	       build_cp_fntype_variant could use it, leading to "canonical
	       types differ for identical types."  */
	    tree v = TYPE_MAIN_VARIANT (type);
	    for (; v; v = TYPE_NEXT_VARIANT (v))
	      if (cp_check_qualified_type (v, variant, var_quals,
					   rqual, cr, false))
		{
		  /* The main variant will not match V, so PREV will never
		     be null.  */
		  TYPE_NEXT_VARIANT (prev) = TYPE_NEXT_VARIANT (variant);
		  break;
		}
	    TYPE_RAISES_EXCEPTIONS (variant) = raises;

	    if (!v)
	      v = build_cp_fntype_variant (TYPE_CANONICAL (variant),
					   rqual, cr, false);
	    TYPE_CANONICAL (variant) = TYPE_CANONICAL (v);
	  }
	else
	  TYPE_RAISES_EXCEPTIONS (variant) = raises;

	if (!TYPE_DEPENDENT_P (variant))
	  /* We no longer know that it's not type-dependent.  */
	  TYPE_DEPENDENT_P_VALID (variant) = false;
      }
}

/* Build the FUNCTION_TYPE or METHOD_TYPE which may throw exceptions
   listed in RAISES.  */

tree
build_exception_variant (tree type, tree raises)
{
  cp_ref_qualifier rqual = type_memfn_rqual (type);
  bool late = TYPE_HAS_LATE_RETURN_TYPE (type);
  return build_cp_fntype_variant (type, rqual, raises, late);
}

/* Given a TEMPLATE_TEMPLATE_PARM node T, create a new
   BOUND_TEMPLATE_TEMPLATE_PARM bound with NEWARGS as its template
   arguments.  */

tree
bind_template_template_parm (tree t, tree newargs)
{
  tree decl = TYPE_NAME (t);
  tree t2;

  t2 = cxx_make_type (BOUND_TEMPLATE_TEMPLATE_PARM);
  decl = build_decl (input_location,
		     TYPE_DECL, DECL_NAME (decl), NULL_TREE);
  SET_DECL_TEMPLATE_PARM_P (decl);

  /* These nodes have to be created to reflect new TYPE_DECL and template
     arguments.  */
  TEMPLATE_TYPE_PARM_INDEX (t2) = copy_node (TEMPLATE_TYPE_PARM_INDEX (t));
  TEMPLATE_PARM_DECL (TEMPLATE_TYPE_PARM_INDEX (t2)) = decl;
  TEMPLATE_TEMPLATE_PARM_TEMPLATE_INFO (t2)
    = build_template_info (TEMPLATE_TEMPLATE_PARM_TEMPLATE_DECL (t), newargs);

  TREE_TYPE (decl) = t2;
  TYPE_NAME (t2) = decl;
  TYPE_STUB_DECL (t2) = decl;
  TYPE_SIZE (t2) = 0;
  SET_TYPE_STRUCTURAL_EQUALITY (t2);

  return t2;
}

/* Called from count_trees via walk_tree.  */

static tree
count_trees_r (tree *tp, int *walk_subtrees, void *data)
{
  ++*((int *) data);

  if (TYPE_P (*tp))
    *walk_subtrees = 0;

  return NULL_TREE;
}

/* Debugging function for measuring the rough complexity of a tree
   representation.  */

int
count_trees (tree t)
{
  int n_trees = 0;
  cp_walk_tree_without_duplicates (&t, count_trees_r, &n_trees);
  return n_trees;
}

/* Called from verify_stmt_tree via walk_tree.  */

static tree
verify_stmt_tree_r (tree* tp, int * /*walk_subtrees*/, void* data)
{
  tree t = *tp;
  hash_table<nofree_ptr_hash <tree_node> > *statements
      = static_cast <hash_table<nofree_ptr_hash <tree_node> > *> (data);
  tree_node **slot;

  if (!STATEMENT_CODE_P (TREE_CODE (t)))
    return NULL_TREE;

  /* If this statement is already present in the hash table, then
     there is a circularity in the statement tree.  */
  gcc_assert (!statements->find (t));

  slot = statements->find_slot (t, INSERT);
  *slot = t;

  return NULL_TREE;
}

/* Debugging function to check that the statement T has not been
   corrupted.  For now, this function simply checks that T contains no
   circularities.  */

void
verify_stmt_tree (tree t)
{
  hash_table<nofree_ptr_hash <tree_node> > statements (37);
  cp_walk_tree (&t, verify_stmt_tree_r, &statements, NULL);
}

/* Check if the type T depends on a type with no linkage and if so,
   return it.  If RELAXED_P then do not consider a class type declared
   within a vague-linkage function to have no linkage.  Remember:
   no-linkage is not the same as internal-linkage*/

tree
no_linkage_check (tree t, bool relaxed_p)
{
  tree r;

  /* Lambda types that don't have mangling scope have no linkage.  We
     check CLASSTYPE_LAMBDA_EXPR for error_mark_node because
     when we get here from pushtag none of the lambda information is
     set up yet, so we want to assume that the lambda has linkage and
     fix it up later if not.  We need to check this even in templates so
     that we properly handle a lambda-expression in the signature.  */
  if (LAMBDA_TYPE_P (t)
      && CLASSTYPE_LAMBDA_EXPR (t) != error_mark_node)
    {
      tree extra = LAMBDA_TYPE_EXTRA_SCOPE (t);
      if (!extra)
	return t;
    }

  /* Otherwise there's no point in checking linkage on template functions; we
     can't know their complete types.  */
  if (processing_template_decl)
    return NULL_TREE;

  switch (TREE_CODE (t))
    {
    case RECORD_TYPE:
      if (TYPE_PTRMEMFUNC_P (t))
	goto ptrmem;
      /* Fall through.  */
    case UNION_TYPE:
      if (!CLASS_TYPE_P (t))
	return NULL_TREE;
      /* Fall through.  */
    case ENUMERAL_TYPE:
      /* Only treat unnamed types as having no linkage if they're at
	 namespace scope.  This is core issue 966.  */
      if (TYPE_UNNAMED_P (t) && TYPE_NAMESPACE_SCOPE_P (t))
	return t;

      for (r = CP_TYPE_CONTEXT (t); ; )
	{
	  /* If we're a nested type of a !TREE_PUBLIC class, we might not
	     have linkage, or we might just be in an anonymous namespace.
	     If we're in a TREE_PUBLIC class, we have linkage.  */
	  if (TYPE_P (r) && !TREE_PUBLIC (TYPE_NAME (r)))
	    return no_linkage_check (TYPE_CONTEXT (t), relaxed_p);
	  else if (TREE_CODE (r) == FUNCTION_DECL)
	    {
	      if (!relaxed_p || !vague_linkage_p (r))
		return t;
	      else
		r = CP_DECL_CONTEXT (r);
	    }
	  else
	    break;
	}

      return NULL_TREE;

    case ARRAY_TYPE:
    case POINTER_TYPE:
    case REFERENCE_TYPE:
    case VECTOR_TYPE:
      return no_linkage_check (TREE_TYPE (t), relaxed_p);

    case OFFSET_TYPE:
    ptrmem:
      r = no_linkage_check (TYPE_PTRMEM_POINTED_TO_TYPE (t),
			    relaxed_p);
      if (r)
	return r;
      return no_linkage_check (TYPE_PTRMEM_CLASS_TYPE (t), relaxed_p);

    case METHOD_TYPE:
    case FUNCTION_TYPE:
      {
	tree parm = TYPE_ARG_TYPES (t);
	if (TREE_CODE (t) == METHOD_TYPE)
	  /* The 'this' pointer isn't interesting; a method has the same
	     linkage (or lack thereof) as its enclosing class.  */
	  parm = TREE_CHAIN (parm);
	for (;
	     parm && parm != void_list_node;
	     parm = TREE_CHAIN (parm))
	  {
	    r = no_linkage_check (TREE_VALUE (parm), relaxed_p);
	    if (r)
	      return r;
	  }
	return no_linkage_check (TREE_TYPE (t), relaxed_p);
      }

    default:
      return NULL_TREE;
    }
}

extern int depth_reached;

void
cxx_print_statistics (void)
{
  print_template_statistics ();
  if (GATHER_STATISTICS)
    fprintf (stderr, "maximum template instantiation depth reached: %d\n",
	     depth_reached);
}

/* Return, as an INTEGER_CST node, the number of elements for TYPE
   (which is an ARRAY_TYPE).  This counts only elements of the top
   array.  */

tree
array_type_nelts_top (tree type)
{
  return fold_build2_loc (input_location,
		      PLUS_EXPR, sizetype,
		      array_type_nelts (type),
		      size_one_node);
}

/* Return, as an INTEGER_CST node, the number of elements for TYPE
   (which is an ARRAY_TYPE).  This one is a recursive count of all
   ARRAY_TYPEs that are clumped together.  */

tree
array_type_nelts_total (tree type)
{
  tree sz = array_type_nelts_top (type);
  type = TREE_TYPE (type);
  while (TREE_CODE (type) == ARRAY_TYPE)
    {
      tree n = array_type_nelts_top (type);
      sz = fold_build2_loc (input_location,
			MULT_EXPR, sizetype, sz, n);
      type = TREE_TYPE (type);
    }
  return sz;
}

/* Return true if FNDECL is std::source_location::current () method.  */

bool
source_location_current_p (tree fndecl)
{
  gcc_checking_assert (TREE_CODE (fndecl) == FUNCTION_DECL
		       && DECL_IMMEDIATE_FUNCTION_P (fndecl));
  if (DECL_NAME (fndecl) == NULL_TREE
      || TREE_CODE (TREE_TYPE (fndecl)) != FUNCTION_TYPE
      || TREE_CODE (TREE_TYPE (TREE_TYPE (fndecl))) != RECORD_TYPE
      || DECL_CONTEXT (fndecl) != TREE_TYPE (TREE_TYPE (fndecl))
      || !id_equal (DECL_NAME (fndecl), "current"))
    return false;

  tree source_location = DECL_CONTEXT (fndecl);
  if (TYPE_NAME (source_location) == NULL_TREE
      || TREE_CODE (TYPE_NAME (source_location)) != TYPE_DECL
      || TYPE_IDENTIFIER (source_location) == NULL_TREE
      || !id_equal (TYPE_IDENTIFIER (source_location),
		    "source_location")
      || !decl_in_std_namespace_p (TYPE_NAME (source_location)))
    return false;

  return true;
}

struct bot_data
{
  splay_tree target_remap;
  bool clear_location;
};

/* Called from break_out_target_exprs via mapcar.  */

static tree
bot_manip (tree* tp, int* walk_subtrees, void* data_)
{
  bot_data &data = *(bot_data*)data_;
  splay_tree target_remap = data.target_remap;
  tree t = *tp;

  if (!TYPE_P (t) && TREE_CONSTANT (t) && !TREE_SIDE_EFFECTS (t))
    {
      /* There can't be any TARGET_EXPRs or their slot variables below this
	 point.  But we must make a copy, in case subsequent processing
	 alters any part of it.  For example, during gimplification a cast
	 of the form (T) &X::f (where "f" is a member function) will lead
	 to replacing the PTRMEM_CST for &X::f with a VAR_DECL.  */
      *walk_subtrees = 0;
      *tp = unshare_expr (t);
      return NULL_TREE;
    }
  if (TREE_CODE (t) == TARGET_EXPR)
    {
      tree u;

      if (TREE_CODE (TREE_OPERAND (t, 1)) == AGGR_INIT_EXPR)
	{
	  u = build_cplus_new (TREE_TYPE (t), TREE_OPERAND (t, 1),
			       tf_warning_or_error);
	  if (u == error_mark_node)
	    return u;
	  if (AGGR_INIT_ZERO_FIRST (TREE_OPERAND (t, 1)))
	    AGGR_INIT_ZERO_FIRST (TREE_OPERAND (u, 1)) = true;
	}
      else
	u = force_target_expr (TREE_TYPE (t), TREE_OPERAND (t, 1),
			       tf_warning_or_error);

      TARGET_EXPR_IMPLICIT_P (u) = TARGET_EXPR_IMPLICIT_P (t);
      TARGET_EXPR_LIST_INIT_P (u) = TARGET_EXPR_LIST_INIT_P (t);
      TARGET_EXPR_DIRECT_INIT_P (u) = TARGET_EXPR_DIRECT_INIT_P (t);

      /* Map the old variable to the new one.  */
      splay_tree_insert (target_remap,
			 (splay_tree_key) TREE_OPERAND (t, 0),
			 (splay_tree_value) TREE_OPERAND (u, 0));

      TREE_OPERAND (u, 1) = break_out_target_exprs (TREE_OPERAND (u, 1),
						    data.clear_location);
      if (TREE_OPERAND (u, 1) == error_mark_node)
	return error_mark_node;

      /* Replace the old expression with the new version.  */
      *tp = u;
      /* We don't have to go below this point; the recursive call to
	 break_out_target_exprs will have handled anything below this
	 point.  */
      *walk_subtrees = 0;
      return NULL_TREE;
    }
  if (TREE_CODE (*tp) == SAVE_EXPR)
    {
      t = *tp;
      splay_tree_node n = splay_tree_lookup (target_remap,
					     (splay_tree_key) t);
      if (n)
	{
	  *tp = (tree)n->value;
	  *walk_subtrees = 0;
	}
      else
	{
	  copy_tree_r (tp, walk_subtrees, NULL);
	  splay_tree_insert (target_remap,
			     (splay_tree_key)t,
			     (splay_tree_value)*tp);
	  /* Make sure we don't remap an already-remapped SAVE_EXPR.  */
	  splay_tree_insert (target_remap,
			     (splay_tree_key)*tp,
			     (splay_tree_value)*tp);
	}
      return NULL_TREE;
    }
  if (TREE_CODE (*tp) == DECL_EXPR
      && VAR_P (DECL_EXPR_DECL (*tp))
      && DECL_ARTIFICIAL (DECL_EXPR_DECL (*tp))
      && !TREE_STATIC (DECL_EXPR_DECL (*tp)))
    {
      tree t;
      splay_tree_node n
	= splay_tree_lookup (target_remap,
			     (splay_tree_key) DECL_EXPR_DECL (*tp));
      if (n)
	t = (tree) n->value;
      else
	{
	  t = create_temporary_var (TREE_TYPE (DECL_EXPR_DECL (*tp)));
	  DECL_INITIAL (t) = DECL_INITIAL (DECL_EXPR_DECL (*tp));
	  splay_tree_insert (target_remap,
			     (splay_tree_key) DECL_EXPR_DECL (*tp),
			     (splay_tree_value) t);
	}
      copy_tree_r (tp, walk_subtrees, NULL);
      DECL_EXPR_DECL (*tp) = t;
      if (data.clear_location && EXPR_HAS_LOCATION (*tp))
	SET_EXPR_LOCATION (*tp, input_location);
      return NULL_TREE;
    }
  if (TREE_CODE