call.c

gcc-2.95.3 Linux下最常用的C编译器

/* Functions related to invoking methods and overloaded functions.
   Copyright (C) 1987, 92-97, 1998, 1999 Free Software Foundation, Inc.
   Contributed by Michael Tiemann ([e-mail]) and
   modified by Brendan Kehoe ([e-mail]).

This file is part of GNU CC.

GNU CC 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 2, or (at your option)
any later version.

GNU CC 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 GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */


/* High-level class interface.  */

#include "config.h"
#include "system.h"
#include "tree.h"
#include "cp-tree.h"
#include "output.h"
#include "flags.h"
#include "rtl.h"
#include "toplev.h"

#include "obstack.h"
#define obstack_chunk_alloc xmalloc
#define obstack_chunk_free free

extern int inhibit_warnings;
extern tree ctor_label, dtor_label;

static tree build_new_method_call PROTO((tree, tree, tree, tree, int));

static tree build_field_call PROTO((tree, tree, tree, tree));
static tree find_scoped_type PROTO((tree, tree, tree));
static struct z_candidate * tourney PROTO((struct z_candidate *));
static int joust PROTO((struct z_candidate *, struct z_candidate *, int));
static int compare_ics PROTO((tree, tree));
static tree build_over_call PROTO((struct z_candidate *, tree, int));
static tree convert_like PROTO((tree, tree));
static void op_error PROTO((enum tree_code, enum tree_code, tree, tree,
			    tree, const char *));
static tree build_object_call PROTO((tree, tree));
static tree resolve_args PROTO((tree));
static struct z_candidate * build_user_type_conversion_1
	PROTO ((tree, tree, int));
static void print_z_candidates PROTO((struct z_candidate *));
static tree build_this PROTO((tree));
static struct z_candidate * splice_viable PROTO((struct z_candidate *));
static int any_viable PROTO((struct z_candidate *));
static struct z_candidate * add_template_candidate
	PROTO((struct z_candidate *, tree, tree, tree, tree, int,
	       unification_kind_t));
static struct z_candidate * add_template_candidate_real
	PROTO((struct z_candidate *, tree, tree, tree, tree, int,
	       tree, unification_kind_t));
static struct z_candidate * add_template_conv_candidate 
        PROTO((struct z_candidate *, tree, tree, tree, tree));
static struct z_candidate * add_builtin_candidates
	PROTO((struct z_candidate *, enum tree_code, enum tree_code,
	       tree, tree *, int));
static struct z_candidate * add_builtin_candidate
	PROTO((struct z_candidate *, enum tree_code, enum tree_code,
	       tree, tree, tree, tree *, tree *, int));
static int is_complete PROTO((tree));
static struct z_candidate * build_builtin_candidate 
	PROTO((struct z_candidate *, tree, tree, tree, tree *, tree *,
	       int));
static struct z_candidate * add_conv_candidate 
	PROTO((struct z_candidate *, tree, tree, tree));
static struct z_candidate * add_function_candidate 
	PROTO((struct z_candidate *, tree, tree, int));
static tree implicit_conversion PROTO((tree, tree, tree, int));
static tree standard_conversion PROTO((tree, tree, tree));
static tree reference_binding PROTO((tree, tree, tree, int));
static tree strip_top_quals PROTO((tree));
static tree non_reference PROTO((tree));
static tree build_conv PROTO((enum tree_code, tree, tree));
static int is_subseq PROTO((tree, tree));
static int maybe_handle_ref_bind PROTO((tree*, tree*));
static void maybe_handle_implicit_object PROTO((tree*));
static struct z_candidate * add_candidate PROTO((struct z_candidate *,
						 tree, tree, int));
static tree source_type PROTO((tree));
static void add_warning PROTO((struct z_candidate *, struct z_candidate *));

tree
build_vfield_ref (datum, type)
     tree datum, type;
{
  tree rval;

  if (datum == error_mark_node)
    return error_mark_node;

  if (TREE_CODE (TREE_TYPE (datum)) == REFERENCE_TYPE)
    datum = convert_from_reference (datum);

  if (! TYPE_USES_COMPLEX_INHERITANCE (type))
    rval = build (COMPONENT_REF, TREE_TYPE (CLASSTYPE_VFIELD (type)),
		  datum, CLASSTYPE_VFIELD (type));
  else
    rval = build_component_ref (datum, DECL_NAME (CLASSTYPE_VFIELD (type)), NULL_TREE, 0);

  return rval;
}

/* Build a call to a member of an object.  I.e., one that overloads
   operator ()(), or is a pointer-to-function or pointer-to-method.  */

static tree
build_field_call (basetype_path, instance_ptr, name, parms)
     tree basetype_path, instance_ptr, name, parms;
{
  tree field, instance;

  if (name == ctor_identifier || name == dtor_identifier)
    return NULL_TREE;

  /* Speed up the common case.  */
  if (instance_ptr == current_class_ptr
      && IDENTIFIER_CLASS_VALUE (name) == NULL_TREE)
    return NULL_TREE;

  field = lookup_field (basetype_path, name, 1, 0);

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

  if (TREE_CODE (field) == FIELD_DECL || TREE_CODE (field) == VAR_DECL)
    {
      /* If it's a field, try overloading operator (),
	 or calling if the field is a pointer-to-function.  */
      instance = build_indirect_ref (instance_ptr, NULL_PTR);
      instance = build_component_ref_1 (instance, field, 0);

      if (instance == error_mark_node)
	return error_mark_node;

      if (IS_AGGR_TYPE (TREE_TYPE (instance)))
	return build_opfncall (CALL_EXPR, LOOKUP_NORMAL,
			       instance, parms, NULL_TREE);
      else if (TREE_CODE (TREE_TYPE (instance)) == POINTER_TYPE)
	{
	  if (TREE_CODE (TREE_TYPE (TREE_TYPE (instance))) == FUNCTION_TYPE)
	    return build_function_call (instance, parms);
	  else if (TREE_CODE (TREE_TYPE (TREE_TYPE (instance)))
		   == METHOD_TYPE)
	    return build_function_call
	      (instance, expr_tree_cons (NULL_TREE, instance_ptr, parms));
	}
    }

  return NULL_TREE;
}

static tree
find_scoped_type (type, inner_name, inner_types)
     tree type, inner_name, inner_types;
{
  tree tags = CLASSTYPE_TAGS (type);

  while (tags)
    {
      /* The TREE_PURPOSE of an enum tag (which becomes a member of the
	 enclosing class) is set to the name for the enum type.  So, if
	 inner_name is `bar', and we strike `baz' for `enum bar { baz }',
	 then this test will be true.  */
      if (TREE_PURPOSE (tags) == inner_name)
	{
	  if (inner_types == NULL_TREE)
	    return TYPE_MAIN_DECL (TREE_VALUE (tags));
	  return resolve_scope_to_name (TREE_VALUE (tags), inner_types);
	}
      tags = TREE_CHAIN (tags);
    }

  /* Look for a TYPE_DECL.  */
  for (tags = TYPE_FIELDS (type); tags; tags = TREE_CHAIN (tags))
    if (TREE_CODE (tags) == TYPE_DECL && DECL_NAME (tags) == inner_name)
      {
	/* Code by raeburn.  */
	if (inner_types == NULL_TREE)
	  return tags;
	return resolve_scope_to_name (TREE_TYPE (tags), inner_types);
      }

  return NULL_TREE;
}

/* Resolve an expression NAME1::NAME2::...::NAMEn to
   the name that names the above nested type.  INNER_TYPES
   is a chain of nested type names (held together by SCOPE_REFs);
   OUTER_TYPE is the type we know to enclose INNER_TYPES.
   Returns NULL_TREE if there is an error.  */

tree
resolve_scope_to_name (outer_type, inner_stuff)
     tree outer_type, inner_stuff;
{
  register tree tmp;
  tree inner_name, inner_type;

  if (outer_type == NULL_TREE && current_class_type != NULL_TREE)
    {
      /* We first try to look for a nesting in our current class context,
         then try any enclosing classes.  */
      tree type = current_class_type;
      
      while (type && (TREE_CODE (type) == RECORD_TYPE
		      || TREE_CODE (type) == UNION_TYPE))
        {
          tree rval = resolve_scope_to_name (type, inner_stuff);

	  if (rval != NULL_TREE)
	    return rval;
	  type = DECL_CONTEXT (TYPE_MAIN_DECL (type));
	}
    }

  if (TREE_CODE (inner_stuff) == SCOPE_REF)
    {
      inner_name = TREE_OPERAND (inner_stuff, 0);
      inner_type = TREE_OPERAND (inner_stuff, 1);
    }
  else
    {
      inner_name = inner_stuff;
      inner_type = NULL_TREE;
    }

  if (outer_type == NULL_TREE)
    {
      tree x;
      /* If we have something that's already a type by itself,
	 use that.  */
      if (IDENTIFIER_HAS_TYPE_VALUE (inner_name))
	{
	  if (inner_type)
	    return resolve_scope_to_name (IDENTIFIER_TYPE_VALUE (inner_name),
					  inner_type);
	  return inner_name;
	}
      
      x = lookup_name (inner_name, 0);

      if (x && TREE_CODE (x) == NAMESPACE_DECL)
	{
	  x = lookup_namespace_name (x, inner_type);
	  return x;
	}
      return NULL_TREE;
    }

  if (! IS_AGGR_TYPE (outer_type))
    return NULL_TREE;

  /* Look for member classes or enums.  */
  tmp = find_scoped_type (outer_type, inner_name, inner_type);

  /* If it's not a type in this class, then go down into the
     base classes and search there.  */
  if (! tmp && TYPE_BINFO (outer_type))
    {
      tree binfos = TYPE_BINFO_BASETYPES (outer_type);
      int i, n_baselinks = binfos ? TREE_VEC_LENGTH (binfos) : 0;

      for (i = 0; i < n_baselinks; i++)
	{
	  tree base_binfo = TREE_VEC_ELT (binfos, i);
	  tmp = resolve_scope_to_name (BINFO_TYPE (base_binfo), inner_stuff);
	  if (tmp)
	    return tmp;
	}
      tmp = NULL_TREE;
    }

  return tmp;
}

/* Returns nonzero iff the destructor name specified in NAME
   (a BIT_NOT_EXPR) matches BASETYPE.  The operand of NAME can take many
   forms...  */

int
check_dtor_name (basetype, name)
     tree basetype, name;
{
  name = TREE_OPERAND (name, 0);

  /* Just accept something we've already complained about.  */
  if (name == error_mark_node)
    return 1;

  if (TREE_CODE (name) == TYPE_DECL)
    name = TREE_TYPE (name);
  else if (TREE_CODE_CLASS (TREE_CODE (name)) == 't')
    /* OK */;
  else if (TREE_CODE (name) == IDENTIFIER_NODE)
    {
      if ((IS_AGGR_TYPE (basetype) && name == constructor_name (basetype))
	  || (TREE_CODE (basetype) == ENUMERAL_TYPE
	      && name == TYPE_IDENTIFIER (basetype)))
	name = basetype;
      else
	name = get_type_value (name);
    }
  else
    my_friendly_abort (980605);

  if (name && TYPE_MAIN_VARIANT (basetype) == TYPE_MAIN_VARIANT (name))
    return 1;
  return 0;
}

/* Build a method call of the form `EXP->SCOPES::NAME (PARMS)'.
   This is how virtual function calls are avoided.  */

tree
build_scoped_method_call (exp, basetype, name, parms)
     tree exp, basetype, name, parms;
{
  /* Because this syntactic form does not allow
     a pointer to a base class to be `stolen',
     we need not protect the derived->base conversion
     that happens here.
     
     @@ But we do have to check access privileges later.  */
  tree binfo, decl;
  tree type = TREE_TYPE (exp);

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

  if (processing_template_decl)
    {
      if (TREE_CODE (name) == BIT_NOT_EXPR
	  && TREE_CODE (TREE_OPERAND (name, 0)) == IDENTIFIER_NODE)
	{
	  tree type = get_aggr_from_typedef (TREE_OPERAND (name, 0), 0);
	  if (type)
	    name = build_min_nt (BIT_NOT_EXPR, type);
	}
      name = build_min_nt (SCOPE_REF, basetype, name);
      return build_min_nt (METHOD_CALL_EXPR, name, exp, parms, NULL_TREE);
    }

  if (TREE_CODE (type) == REFERENCE_TYPE)
    type = TREE_TYPE (type);

  if (TREE_CODE (basetype) == TREE_VEC)
    {
      binfo = basetype;
      basetype = BINFO_TYPE (binfo);
    }
  else
    binfo = NULL_TREE;

  /* Check the destructor call syntax.  */
  if (TREE_CODE (name) == BIT_NOT_EXPR)
    {
      /* We can get here if someone writes their destructor call like
	 `obj.NS::~T()'; this isn't really a scoped method call, so hand
	 it off.  */
      if (TREE_CODE (basetype) == NAMESPACE_DECL)
	return build_method_call (exp, name, parms, NULL_TREE, LOOKUP_NORMAL);

      if (! check_dtor_name (basetype, name))
	cp_error ("qualified type `%T' does not match destructor name `~%T'",
		  basetype, TREE_OPERAND (name, 0));

      /* Destructors can be "called" for simple types; see 5.2.4 and 12.4 Note
	 that explicit ~int is caught in the parser; this deals with typedefs
	 and template parms.  */
      if (! IS_AGGR_TYPE (basetype))
	{
	  if (TYPE_MAIN_VARIANT (type) != TYPE_MAIN_VARIANT (basetype))
	    cp_error ("type of `%E' does not match destructor type `%T' (type was `%T')",
		      exp, basetype, type);

	  return cp_convert (void_type_node, exp);
	}
    }

  if (! is_aggr_type (basetype, 1))
    return error_mark_node;

  if (! IS_AGGR_TYPE (type))
    {
      cp_error ("base object `%E' of scoped method call is of non-aggregate type `%T'",
		exp, type);
      return error_mark_node;
    }

  if (! binfo)
    {
      binfo = get_binfo (basetype, type, 1);
      if (binfo == error_mark_node)
	return error_mark_node;
      if (! binfo)
	error_not_base_type (basetype, type);
    }

  if (binfo)
    {
      if (TREE_CODE (exp) == INDIRECT_REF)
	decl = build_indirect_ref
	  (convert_pointer_to_real
	   (binfo, build_unary_op (ADDR_EXPR, exp, 0)), NULL_PTR);
      else
	decl = build_scoped_ref (exp, basetype);

      /* Call to a destructor.  */
      if (TREE_CODE (name) == BIT_NOT_EXPR)
	{
	  if (! TYPE_HAS_DESTRUCTOR (TREE_TYPE (decl)))
	    return cp_convert (void_type_node, exp);
	  
	  return build_delete (TREE_TYPE (decl), decl, integer_two_node,
			       LOOKUP_NORMAL|LOOKUP_NONVIRTUAL|LOOKUP_DESTRUCTOR,
			       0);
	}

      /* Call to a method.  */
      return build_method_call (decl, name, parms, binfo,
				LOOKUP_NORMAL|LOOKUP_NONVIRTUAL);
    }
  return error_mark_node;
}

/* We want the address of a function or method.  We avoid creating a
   pointer-to-member function.  */

tree
build_addr_func (function)
     tree function;
{
  tree type = TREE_TYPE (function);

  /* We have to do these by hand to avoid real pointer to member