typeck2.c

gcc-2.95.3 Linux下最常用的C编译器

/* Report error messages, build initializers, and perform
   some front-end optimizations for C++ compiler.
   Copyright (C) 1987, 88, 89, 92-98, 1999 Free Software Foundation, Inc.
   Hacked by Michael Tiemann ([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.  */


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

   There are also routines to build RETURN_STMT nodes and CASE_STMT nodes,
   and to process initializations in declarations (since they work
   like a strange sort of assignment).  */

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

static tree process_init_constructor PROTO((tree, tree, tree *));
static void ack PVPROTO ((const char *, ...)) ATTRIBUTE_PRINTF_1;

extern int errorcount;
extern int sorrycount;

/* Print an error message stemming from an attempt to use
   BASETYPE as a base class for TYPE.  */

tree
error_not_base_type (basetype, type)
     tree basetype, type;
{
  if (TREE_CODE (basetype) == FUNCTION_DECL)
    basetype = DECL_CLASS_CONTEXT (basetype);
  cp_error ("type `%T' is not a base type for type `%T'", basetype, type);
  return error_mark_node;
}

tree
binfo_or_else (parent_or_type, type)
     tree parent_or_type, type;
{
  tree binfo;
  if (TYPE_MAIN_VARIANT (parent_or_type) == TYPE_MAIN_VARIANT (type))
    return TYPE_BINFO (parent_or_type);
  if ((binfo = get_binfo (parent_or_type, TYPE_MAIN_VARIANT (type), 0)))
    {
      if (binfo == error_mark_node)
	return NULL_TREE;
      return binfo;
    }
  error_not_base_type (parent_or_type, type);
  return NULL_TREE;
}

/* According to ARM $7.1.6, "A `const' object may be initialized, but its
   value may not be changed thereafter.  Thus, we emit hard errors for these,
   rather than just pedwarns.  If `SOFT' is 1, then we just pedwarn.  (For
   example, conversions to references.)  */

void
readonly_error (arg, string, soft)
     tree arg;
     const char *string;
     int soft;
{
  const char *fmt;
  void (*fn) PVPROTO ((const char *, ...));

  if (soft)
    fn = cp_pedwarn;
  else
    fn = cp_error;

  if (TREE_CODE (arg) == COMPONENT_REF)
    {
      if (TYPE_READONLY (TREE_TYPE (TREE_OPERAND (arg, 0))))
        fmt = "%s of member `%D' in read-only structure";
      else
        fmt = "%s of read-only member `%D'";
      (*fn) (fmt, string, TREE_OPERAND (arg, 1));
    }
  else if (TREE_CODE (arg) == VAR_DECL)
    {
      if (DECL_LANG_SPECIFIC (arg)
	  && DECL_IN_AGGR_P (arg)
	  && !TREE_STATIC (arg))
	fmt = "%s of constant field `%D'";
      else
	fmt = "%s of read-only variable `%D'";
      (*fn) (fmt, string, arg);
    }
  else if (TREE_CODE (arg) == PARM_DECL)
    (*fn) ("%s of read-only parameter `%D'", string, arg);
  else if (TREE_CODE (arg) == INDIRECT_REF
           && TREE_CODE (TREE_TYPE (TREE_OPERAND (arg, 0))) == REFERENCE_TYPE
           && (TREE_CODE (TREE_OPERAND (arg, 0)) == VAR_DECL
               || TREE_CODE (TREE_OPERAND (arg, 0)) == PARM_DECL))
    (*fn) ("%s of read-only reference `%D'", string, TREE_OPERAND (arg, 0));
  else if (TREE_CODE (arg) == RESULT_DECL)
    (*fn) ("%s of read-only named return value `%D'", string, arg);
  else if (TREE_CODE (arg) == FUNCTION_DECL)
    (*fn) ("%s of function `%D'", string, arg);
  else
    (*fn) ("%s of read-only location", string);
}

/* Print an error message for invalid use of a type which declares
   virtual functions which are not inheritable.  */

void
abstract_virtuals_error (decl, type)
     tree decl;
     tree type;
{
  tree u = CLASSTYPE_ABSTRACT_VIRTUALS (type);
  tree tu;

  if (decl)
    {
      if (TREE_CODE (decl) == RESULT_DECL)
	return;

      if (TREE_CODE (decl) == VAR_DECL)
	cp_error ("cannot declare variable `%D' to be of type `%T'",
		    decl, type);
      else if (TREE_CODE (decl) == PARM_DECL)
	cp_error ("cannot declare parameter `%D' to be of type `%T'",
		    decl, type);
      else if (TREE_CODE (decl) == FIELD_DECL)
	cp_error ("cannot declare field `%D' to be of type `%T'",
		    decl, type);
      else if (TREE_CODE (decl) == FUNCTION_DECL
	       && TREE_CODE (TREE_TYPE (decl)) == METHOD_TYPE)
	cp_error ("invalid return type for method `%#D'", decl);
      else if (TREE_CODE (decl) == FUNCTION_DECL)
	cp_error ("invalid return type for function `%#D'", decl);
    }
  else
    cp_error ("cannot allocate an object of type `%T'", type);

  /* Only go through this once.  */
  if (TREE_PURPOSE (u) == NULL_TREE)
    {
      TREE_PURPOSE (u) = error_mark_node;

      error ("  since the following virtual functions are abstract:");
      for (tu = u; tu; tu = TREE_CHAIN (tu))
	cp_error_at ("\t%#D", TREE_VALUE (tu));
    }
  else
    cp_error ("  since type `%T' has abstract virtual functions", type);
}

/* Print an error message for invalid use of a signature type.
   Signatures are treated similar to abstract classes here, they
   cannot be instantiated.  */

void
signature_error (decl, type)
     tree decl;
     tree type;
{
  if (decl)
    {
      if (TREE_CODE (decl) == RESULT_DECL)
	return;

      if (TREE_CODE (decl) == VAR_DECL)
	cp_error ("cannot declare variable `%D' to be of signature type `%T'",
		  decl, type);
      else if (TREE_CODE (decl) == PARM_DECL)
	cp_error ("cannot declare parameter `%D' to be of signature type `%T'",
		  decl, type);
      else if (TREE_CODE (decl) == FIELD_DECL)
	cp_error ("cannot declare field `%D' to be of signature type `%T'",
		  decl, type);
      else if (TREE_CODE (decl) == FUNCTION_DECL
	       && TREE_CODE (TREE_TYPE (decl)) == METHOD_TYPE)
	cp_error ("invalid return type for method `%#D'", decl);
      else if (TREE_CODE (decl) == FUNCTION_DECL)
	cp_error ("invalid return type for function `%#D'", decl);
    }
  else
    cp_error ("cannot allocate an object of signature type `%T'", type);
}

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

void
incomplete_type_error (value, type)
     tree value;
     tree type;
{
  /* Avoid duplicate error message.  */
  if (TREE_CODE (type) == ERROR_MARK)
    return;

retry:
  /* We must print an error message.  Be clever about what it says.  */

  switch (TREE_CODE (type))
    {
    case RECORD_TYPE:
    case UNION_TYPE:
    case ENUMERAL_TYPE:
      cp_error ("invalid use of undefined type `%#T'", type);
      cp_error_at ("forward declaration of `%#T'", type);
      break;

    case VOID_TYPE:
      cp_error ("invalid use of void expression");
      break;

    case ARRAY_TYPE:
      if (TYPE_DOMAIN (type))
        {
          type = TREE_TYPE (type);
          goto retry;
        }
      cp_error ("invalid use of array with unspecified bounds");
      break;

    case OFFSET_TYPE:
    bad_member:
      cp_error ("invalid use of member (did you forget the `&' ?)");
      break;

    case TEMPLATE_TYPE_PARM:
      cp_error ("invalid use of template type parameter");
      break;

    case UNKNOWN_TYPE:
      if (value && TREE_CODE (value) == COMPONENT_REF)
        goto bad_member;
      else if (value && TREE_CODE (value) == ADDR_EXPR)
        cp_error ("address of overloaded function with no contextual type information");
      else if (value && TREE_CODE (value) == OVERLOAD)
        cp_error ("overloaded function with no contextual type information");
      else
        cp_error ("insufficient contextual information to determine type");
      break;
    
    default:
      my_friendly_abort (108);
    }

  if (value != 0 && (TREE_CODE (value) == VAR_DECL
		     || TREE_CODE (value) == PARM_DECL))
    cp_error_at ("incomplete `%D' defined here", value);
}

/* Like error(), but don't call report_error_function().  */

static void
ack VPROTO ((const char *msg, ...))
{
#ifndef ANSI_PROTOTYPES
  const char *msg;
#endif
  va_list ap;
  extern char * progname;
  
  VA_START (ap, msg);

#ifndef ANSI_PROTOTYPES
  msg = va_arg (ap, const char *);
#endif
  
  if (input_filename)
    fprintf (stderr, "%s:%d: ", input_filename, lineno);
  else
    fprintf (stderr, "%s: ", progname);

  vfprintf (stderr, msg, ap);
  va_end (ap);
  
  fprintf (stderr, "\n");
}
  
/* There are times when the compiler can get very confused, confused
   to the point of giving up by aborting, simply because of previous
   input errors.  It is much better to have the user go back and
   correct those errors first, and see if it makes us happier, than it
   is to abort on him.  This is because when one has a 10,000 line
   program, and the compiler comes back with ``core dump'', the user
   is left not knowing even where to begin to fix things and no place
   to even try and work around things.

   The parameter is to uniquely identify the problem to the user, so
   that they can say, I am having problem 59, and know that fix 7 will
   probably solve their problem.  Or, we can document what problem
   59 is, so they can understand how to work around it, should they
   ever run into it.

   We used to tell people to "fix the above error[s] and try recompiling
   the program" via a call to fatal, but that message tended to look
   silly.  So instead, we just do the equivalent of a call to fatal in the
   same situation (call exit).

   We used to assign sequential numbers for the aborts; now we use an
   encoding of the date the abort was added, since that has more meaning
   when we only see the error message.  */

static int abortcount = 0;

void
my_friendly_abort (i)
     int i;
{
  /* if the previous error came through here, i.e. report_error_function
     ended up calling us again, don't just exit; we want a diagnostic of
     some kind.  */
  if (abortcount == 1)
    current_function_decl = NULL_TREE;
  else if (errorcount > 0 || sorrycount > 0)
    {
      if (abortcount > 1)
	{
	  if (i == 0)
	    ack ("Internal compiler error.");
	  else
	    ack ("Internal compiler error %d.", i);
	  ack ("Please submit a full bug report.");
	  ack ("See %s for instructions.", GCCBUGURL);
	}
      else
	error ("confused by earlier errors, bailing out");
      
      exit (34);
    }
  ++abortcount;

  if (i == 0)
    error ("Internal compiler error.");
  else
    error ("Internal compiler error %d.", i);

  error ("Please submit a full bug report.");
  fatal ("See %s for instructions.", GCCBUGURL);
}

void
my_friendly_assert (cond, where)
     int cond, where;
{
  if (cond == 0)
    my_friendly_abort (where);
}

/* Return nonzero if VALUE is a valid constant-valued expression
   for use in initializing a static variable; one that can be an
   element of a "constant" initializer.

   Return null_pointer_node if the value is absolute;
   if it is relocatable, return the variable that determines the relocation.
   We assume that VALUE has been folded as much as possible;
   therefore, we do not need to check for such things as
   arithmetic-combinations of integers.  */

tree
initializer_constant_valid_p (value, endtype)
     tree value;
     tree endtype;
{
  switch (TREE_CODE (value))
    {
    case CONSTRUCTOR:
      if (TREE_CODE (TREE_TYPE (value)) == UNION_TYPE
	  && TREE_CONSTANT (value))
	return
	  initializer_constant_valid_p (TREE_VALUE (CONSTRUCTOR_ELTS (value)),
					endtype);
	
      return TREE_STATIC (value) ? null_pointer_node : 0;

    case INTEGER_CST:
    case REAL_CST:
    case STRING_CST:
    case COMPLEX_CST:
    case PTRMEM_CST:
      return null_pointer_node;

    case ADDR_EXPR:
      return TREE_OPERAND (value, 0);

    case NON_LVALUE_EXPR:
      return initializer_constant_valid_p (TREE_OPERAND (value, 0), endtype);

    case CONVERT_EXPR:
    case NOP_EXPR:
      /* Allow conversions between pointer types.  */
      if (POINTER_TYPE_P (TREE_TYPE (value))
	  && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (value, 0))))