gcc/cp/typeck.c

   1 /* Build expressions with type checking for C++ compiler.
   2    Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
   4    Hacked by Michael Tiemann (tiemann@cygnus.com)
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2, or (at your option)
  11 any later version.
  12
  13 GCC is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING.  If not, write to
  20 the Free Software Foundation, 59 Temple Place - Suite 330,
  21 Boston, MA 02111-1307, USA.  */
  22
  23
  24 /* This file is part of the C++ front end.
  25    It contains routines to build C++ expressions given their operands,
  26    including computing the types of the result, C and C++ specific error
  27    checks, and some optimization.  */
  28
  29 #include "config.h"
  30 #include "system.h"
  31 #include "coretypes.h"
  32 #include "tm.h"
  33 #include "tree.h"
  34 #include "rtl.h"
  35 #include "expr.h"
  36 #include "cp-tree.h"
  37 #include "tm_p.h"
  38 #include "flags.h"
  39 #include "output.h"
  40 #include "toplev.h"
  41 #include "diagnostic.h"
  42 #include "target.h"
  43 #include "convert.h"
  44
  45 static tree convert_for_assignment (tree, tree, const char *, tree, int);
  46 static tree cp_pointer_int_sum (enum tree_code, tree, tree);
  47 static tree rationalize_conditional_expr (enum tree_code, tree);
  48 static int comp_ptr_ttypes_real (tree, tree, int);
  49 static int comp_ptr_ttypes_const (tree, tree);
  50 static bool comp_except_types (tree, tree, bool);
  51 static bool comp_array_types (tree, tree, bool);
  52 static tree common_base_type (tree, tree);
  53 static tree pointer_diff (tree, tree, tree);
  54 static tree get_delta_difference (tree, tree, int);
  55 static void casts_away_constness_r (tree *, tree *);
  56 static bool casts_away_constness (tree, tree);
  57 static void maybe_warn_about_returning_address_of_local (tree);
  58 static tree lookup_destructor (tree, tree, tree);
  59
  60 /* Return the target type of TYPE, which means return T for:
  61    T*, T&, T[], T (...), and otherwise, just T.  */
  62
  63 tree
  64 target_type (tree type)
  65 {
  66   type = non_reference (type);
  67   while (TREE_CODE (type) == POINTER_TYPE
  68          || TREE_CODE (type) == ARRAY_TYPE
  69          || TREE_CODE (type) == FUNCTION_TYPE
  70          || TREE_CODE (type) == METHOD_TYPE
  71          || TYPE_PTRMEM_P (type))
  72     type = TREE_TYPE (type);
  73   return type;
  74 }
  75
  76 /* Do `exp = require_complete_type (exp);' to make sure exp
  77    does not have an incomplete type.  (That includes void types.)
  78    Returns the error_mark_node if the VALUE does not have
  79    complete type when this function returns.  */
  80
  81 tree
  82 require_complete_type (tree value)
  83 {
  84   tree type;
  85
  86   if (processing_template_decl || value == error_mark_node)
  87     return value;
  88
  89   if (TREE_CODE (value) == OVERLOAD)
  90     type = unknown_type_node;
  91   else
  92     type = TREE_TYPE (value);
  93
  94   if (type == error_mark_node)
  95     return error_mark_node;
  96
  97   /* First, detect a valid value with a complete type.  */
  98   if (COMPLETE_TYPE_P (type))
  99     return value;
 100
 101   if (complete_type_or_else (type, value))
 102     return value;
 103   else
 104     return error_mark_node;
 105 }
 106
 107 /* Try to complete TYPE, if it is incomplete.  For example, if TYPE is
 108    a template instantiation, do the instantiation.  Returns TYPE,
 109    whether or not it could be completed, unless something goes
 110    horribly wrong, in which case the error_mark_node is returned.  */
 111
 112 tree
 113 complete_type (tree type)
 114 {
 115   if (type == NULL_TREE)
 116     /* Rather than crash, we return something sure to cause an error
 117        at some point.  */
 118     return error_mark_node;
 119
 120   if (type == error_mark_node || COMPLETE_TYPE_P (type))
 121     ;
 122   else if (TREE_CODE (type) == ARRAY_TYPE && TYPE_DOMAIN (type))
 123     {
 124       tree t = complete_type (TREE_TYPE (type));
 125       if (COMPLETE_TYPE_P (t) && !dependent_type_p (type))
 126         layout_type (type);
 127       TYPE_NEEDS_CONSTRUCTING (type)
 128         = TYPE_NEEDS_CONSTRUCTING (TYPE_MAIN_VARIANT (t));
 129       TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type)
 130         = TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TYPE_MAIN_VARIANT (t));
 131     }
 132   else if (CLASS_TYPE_P (type) && CLASSTYPE_TEMPLATE_INSTANTIATION (type))
 133     instantiate_class_template (TYPE_MAIN_VARIANT (type));
 134
 135   return type;
 136 }
 137
 138 /* Like complete_type, but issue an error if the TYPE cannot be completed.
 139    VALUE is used for informative diagnostics.  DIAG_TYPE indicates the type
 140    of diagnostic: 0 for an error, 1 for a warning, 2 for a pedwarn.
 141    Returns NULL_TREE if the type cannot be made complete.  */
 142
 143 tree
 144 complete_type_or_diagnostic (tree type, tree value, int diag_type)
 145 {
 146   type = complete_type (type);
 147   if (type == error_mark_node)
 148     /* We already issued an error.  */
 149     return NULL_TREE;
 150   else if (!COMPLETE_TYPE_P (type))
 151     {
 152       cxx_incomplete_type_diagnostic (value, type, diag_type);
 153       return NULL_TREE;
 154     }
 155   else
 156     return type;
 157 }
 158
 159 /* Return truthvalue of whether type of EXP is instantiated.  */
 160
 161 int
 162 type_unknown_p (tree exp)
 163 {
 164   return (TREE_CODE (exp) == TREE_LIST
 165           || TREE_TYPE (exp) == unknown_type_node);
 166 }
 167
 168 \f
 169 /* Return the common type of two parameter lists.
 170    We assume that comptypes has already been done and returned 1;
 171    if that isn't so, this may crash.
 172
 173    As an optimization, free the space we allocate if the parameter
 174    lists are already common.  */
 175
 176 tree
 177 commonparms (tree p1, tree p2)
 178 {
 179   tree oldargs = p1, newargs, n;
 180   int i, len;
 181   int any_change = 0;
 182
 183   len = list_length (p1);
 184   newargs = tree_last (p1);
 185
 186   if (newargs == void_list_node)
 187     i = 1;
 188   else
 189     {
 190       i = 0;
 191       newargs = 0;
 192     }
 193
 194   for (; i < len; i++)
 195     newargs = tree_cons (NULL_TREE, NULL_TREE, newargs);
 196
 197   n = newargs;
 198
 199   for (i = 0; p1;
 200        p1 = TREE_CHAIN (p1), p2 = TREE_CHAIN (p2), n = TREE_CHAIN (n), i++)
 201     {
 202       if (TREE_PURPOSE (p1) && !TREE_PURPOSE (p2))
 203         {
 204           TREE_PURPOSE (n) = TREE_PURPOSE (p1);
 205           any_change = 1;
 206         }
 207       else if (! TREE_PURPOSE (p1))
 208         {
 209           if (TREE_PURPOSE (p2))
 210             {
 211               TREE_PURPOSE (n) = TREE_PURPOSE (p2);
 212               any_change = 1;
 213             }
 214         }
 215       else
 216         {
 217           if (1 != simple_cst_equal (TREE_PURPOSE (p1), TREE_PURPOSE (p2)))
 218             any_change = 1;
 219           TREE_PURPOSE (n) = TREE_PURPOSE (p2);
 220         }
 221       if (TREE_VALUE (p1) != TREE_VALUE (p2))
 222         {
 223           any_change = 1;
 224           TREE_VALUE (n) = merge_types (TREE_VALUE (p1), TREE_VALUE (p2));
 225         }
 226       else
 227         TREE_VALUE (n) = TREE_VALUE (p1);
 228     }
 229   if (! any_change)
 230     return oldargs;
 231
 232   return newargs;
 233 }
 234
 235 /* Given a type, perhaps copied for a typedef,
 236    find the "original" version of it.  */
 237 tree
 238 original_type (tree t)
 239 {
 240   while (TYPE_NAME (t) != NULL_TREE)
 241     {
 242       tree x = TYPE_NAME (t);
 243       if (TREE_CODE (x) != TYPE_DECL)
 244         break;
 245       x = DECL_ORIGINAL_TYPE (x);
 246       if (x == NULL_TREE)
 247         break;
 248       t = x;
 249     }
 250   return t;
 251 }
 252
 253 /* T1 and T2 are arithmetic or enumeration types.  Return the type
 254    that will result from the "usual arithmetic conversions" on T1 and
 255    T2 as described in [expr].  */
 256
 257 tree
 258 type_after_usual_arithmetic_conversions (tree t1, tree t2)
 259 {
 260   enum tree_code code1 = TREE_CODE (t1);
 261   enum tree_code code2 = TREE_CODE (t2);
 262   tree attributes;
 263
 264   /* FIXME: Attributes.  */
 265   my_friendly_assert (ARITHMETIC_TYPE_P (t1)
 266                       || TREE_CODE (t1) == COMPLEX_TYPE
 267                       || TREE_CODE (t1) == ENUMERAL_TYPE,
 268                       19990725);
 269   my_friendly_assert (ARITHMETIC_TYPE_P (t2)
 270                       || TREE_CODE (t2) == COMPLEX_TYPE
 271                       || TREE_CODE (t2) == ENUMERAL_TYPE,
 272                       19990725);
 273
 274   /* In what follows, we slightly generalize the rules given in [expr] so
 275      as to deal with `long long' and `complex'.  First, merge the
 276      attributes.  */
 277   attributes = (*targetm.merge_type_attributes) (t1, t2);
 278
 279   /* If one type is complex, form the common type of the non-complex
 280      components, then make that complex.  Use T1 or T2 if it is the
 281      required type.  */
 282   if (code1 == COMPLEX_TYPE || code2 == COMPLEX_TYPE)
 283     {
 284       tree subtype1 = code1 == COMPLEX_TYPE ? TREE_TYPE (t1) : t1;
 285       tree subtype2 = code2 == COMPLEX_TYPE ? TREE_TYPE (t2) : t2;
 286       tree subtype
 287         = type_after_usual_arithmetic_conversions (subtype1, subtype2);
 288
 289       if (code1 == COMPLEX_TYPE && TREE_TYPE (t1) == subtype)
 290         return build_type_attribute_variant (t1, attributes);
 291       else if (code2 == COMPLEX_TYPE && TREE_TYPE (t2) == subtype)
 292         return build_type_attribute_variant (t2, attributes);
 293       else
 294         return build_type_attribute_variant (build_complex_type (subtype),
 295                                              attributes);
 296     }
 297
 298   /* If only one is real, use it as the result.  */
 299   if (code1 == REAL_TYPE && code2 != REAL_TYPE)
 300     return build_type_attribute_variant (t1, attributes);
 301   if (code2 == REAL_TYPE && code1 != REAL_TYPE)
 302     return build_type_attribute_variant (t2, attributes);
 303
 304   /* Perform the integral promotions.  */
 305   if (code1 != REAL_TYPE)
 306     {
 307       t1 = type_promotes_to (t1);
 308       t2 = type_promotes_to (t2);
 309     }
 310
 311   /* Both real or both integers; use the one with greater precision.  */
 312   if (TYPE_PRECISION (t1) > TYPE_PRECISION (t2))
 313     return build_type_attribute_variant (t1, attributes);
 314   else if (TYPE_PRECISION (t2) > TYPE_PRECISION (t1))
 315     return build_type_attribute_variant (t2, attributes);
 316
 317   /* The types are the same; no need to do anything fancy.  */
 318   if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
 319     return build_type_attribute_variant (t1, attributes);
 320
 321   if (code1 != REAL_TYPE)
 322     {
 323       /* If one is a sizetype, use it so size_binop doesn't blow up.  */
 324       if (TYPE_IS_SIZETYPE (t1) > TYPE_IS_SIZETYPE (t2))
 325         return build_type_attribute_variant (t1, attributes);
 326       if (TYPE_IS_SIZETYPE (t2) > TYPE_IS_SIZETYPE (t1))
 327         return build_type_attribute_variant (t2, attributes);
 328
 329       /* If one is unsigned long long, then convert the other to unsigned
 330          long long.  */
 331       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_long_unsigned_type_node)
 332           || same_type_p (TYPE_MAIN_VARIANT (t2), long_long_unsigned_type_node))
 333         return build_type_attribute_variant (long_long_unsigned_type_node,
 334                                              attributes);
 335       /* If one is a long long, and the other is an unsigned long, and
 336          long long can represent all the values of an unsigned long, then
 337          convert to a long long.  Otherwise, convert to an unsigned long
 338          long.  Otherwise, if either operand is long long, convert the
 339          other to long long.
 340
 341          Since we're here, we know the TYPE_PRECISION is the same;
 342          therefore converting to long long cannot represent all the values
 343          of an unsigned long, so we choose unsigned long long in that
 344          case.  */
 345       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_long_integer_type_node)
 346           || same_type_p (TYPE_MAIN_VARIANT (t2), long_long_integer_type_node))
 347         {
 348           tree t = ((TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 349                     ? long_long_unsigned_type_node
 350                     : long_long_integer_type_node);
 351           return build_type_attribute_variant (t, attributes);
 352         }
 353
 354       /* Go through the same procedure, but for longs.  */
 355       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_unsigned_type_node)
 356           || same_type_p (TYPE_MAIN_VARIANT (t2), long_unsigned_type_node))
 357         return build_type_attribute_variant (long_unsigned_type_node,
 358                                              attributes);
 359       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_integer_type_node)
 360           || same_type_p (TYPE_MAIN_VARIANT (t2), long_integer_type_node))
 361         {
 362           tree t = ((TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 363                     ? long_unsigned_type_node : long_integer_type_node);
 364           return build_type_attribute_variant (t, attributes);
 365         }
 366       /* Otherwise prefer the unsigned one.  */
 367       if (TYPE_UNSIGNED (t1))
 368         return build_type_attribute_variant (t1, attributes);
 369       else
 370         return build_type_attribute_variant (t2, attributes);
 371     }
 372   else
 373     {
 374       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_double_type_node)
 375           || same_type_p (TYPE_MAIN_VARIANT (t2), long_double_type_node))
 376         return build_type_attribute_variant (long_double_type_node,
 377                                              attributes);
 378       if (same_type_p (TYPE_MAIN_VARIANT (t1), double_type_node)
 379           || same_type_p (TYPE_MAIN_VARIANT (t2), double_type_node))
 380         return build_type_attribute_variant (double_type_node,
 381                                              attributes);
 382       if (same_type_p (TYPE_MAIN_VARIANT (t1), float_type_node)
 383           || same_type_p (TYPE_MAIN_VARIANT (t2), float_type_node))
 384         return build_type_attribute_variant (float_type_node,
 385                                              attributes);
 386
 387       /* Two floating-point types whose TYPE_MAIN_VARIANTs are none of
 388          the standard C++ floating-point types.  Logic earlier in this
 389          function has already eliminated the possibility that
 390          TYPE_PRECISION (t2) != TYPE_PRECISION (t1), so there's no
 391          compelling reason to choose one or the other.  */
 392       return build_type_attribute_variant (t1, attributes);
 393     }
 394 }
 395
 396 /* Subroutine of composite_pointer_type to implement the recursive
 397    case.  See that function for documentation fo the parameters.  */
 398
 399 static tree
 400 composite_pointer_type_r (tree t1, tree t2, const char* location)
 401 {
 402   tree pointee1;
 403   tree pointee2;
 404   tree result_type;
 405   tree attributes;
 406
 407   /* Determine the types pointed to by T1 and T2.  */
 408   if (TREE_CODE (t1) == POINTER_TYPE)
 409     {
 410       pointee1 = TREE_TYPE (t1);
 411       pointee2 = TREE_TYPE (t2);
 412     }
 413   else
 414     {
 415       pointee1 = TYPE_PTRMEM_POINTED_TO_TYPE (t1);
 416       pointee2 = TYPE_PTRMEM_POINTED_TO_TYPE (t2);
 417     }
 418
 419   /* [expr.rel]
 420
 421      Otherwise, the composite pointer type is a pointer type
 422      similar (_conv.qual_) to the type of one of the operands,
 423      with a cv-qualification signature (_conv.qual_) that is the
 424      union of the cv-qualification signatures of the operand
 425      types.  */
 426   if (same_type_ignoring_top_level_qualifiers_p (pointee1, pointee2))
 427     result_type = pointee1;
 428   else if ((TREE_CODE (pointee1) == POINTER_TYPE
 429             && TREE_CODE (pointee2) == POINTER_TYPE)
 430            || (TYPE_PTR_TO_MEMBER_P (pointee1)
 431                && TYPE_PTR_TO_MEMBER_P (pointee2)))
 432     result_type = composite_pointer_type_r (pointee1, pointee2, location);
 433   else
 434     {
 435       pedwarn ("%s between distinct pointer types `%T' and `%T' "
 436                "lacks a cast",
 437                location, t1, t2);
 438       result_type = void_type_node;
 439     }
 440   result_type = cp_build_qualified_type (result_type,
 441                                          (cp_type_quals (pointee1)
 442                                           | cp_type_quals (pointee2)));
 443   /* If the original types were pointers to members, so is the
 444      result.  */
 445   if (TYPE_PTR_TO_MEMBER_P (t1))
 446     {
 447       if (!same_type_p (TYPE_PTRMEM_CLASS_TYPE (t1),
 448                         TYPE_PTRMEM_CLASS_TYPE (t2)))
 449         pedwarn ("%s between distinct pointer types `%T' and `%T' "
 450                  "lacks a cast",
 451                  location, t1, t2);
 452       result_type = build_ptrmem_type (TYPE_PTRMEM_CLASS_TYPE (t1),
 453                                        result_type);
 454     }
 455   else
 456     result_type = build_pointer_type (result_type);
 457
 458   /* Merge the attributes.  */
 459   attributes = (*targetm.merge_type_attributes) (t1, t2);
 460   return build_type_attribute_variant (result_type, attributes);
 461 }
 462
 463 /* Return the composite pointer type (see [expr.rel]) for T1 and T2.
 464    ARG1 and ARG2 are the values with those types.  The LOCATION is a
 465    string describing the current location, in case an error occurs.
 466
 467    This routine also implements the computation of a common type for
 468    pointers-to-members as per [expr.eq].  */
 469
 470 tree
 471 composite_pointer_type (tree t1, tree t2, tree arg1, tree arg2,
 472                         const char* location)
 473 {
 474   tree class1;
 475   tree class2;
 476
 477   /* [expr.rel]
 478
 479      If one operand is a null pointer constant, the composite pointer
 480      type is the type of the other operand.  */
 481   if (null_ptr_cst_p (arg1))
 482     return t2;
 483   if (null_ptr_cst_p (arg2))
 484     return t1;
 485
 486   /* We have:
 487
 488        [expr.rel]
 489
 490        If one of the operands has type "pointer to cv1 void*", then
 491        the other has type "pointer to cv2T", and the composite pointer
 492        type is "pointer to cv12 void", where cv12 is the union of cv1
 493        and cv2.
 494
 495     If either type is a pointer to void, make sure it is T1.  */
 496   if (TREE_CODE (t2) == POINTER_TYPE && VOID_TYPE_P (TREE_TYPE (t2)))
 497     {
 498       tree t;
 499       t = t1;
 500       t1 = t2;
 501       t2 = t;
 502     }
 503
 504   /* Now, if T1 is a pointer to void, merge the qualifiers.  */
 505   if (TREE_CODE (t1) == POINTER_TYPE && VOID_TYPE_P (TREE_TYPE (t1)))
 506     {
 507       tree attributes;
 508       tree result_type;
 509
 510       if (pedantic && TYPE_PTRFN_P (t2))
 511         pedwarn ("ISO C++ forbids %s between pointer of type `void *' and pointer-to-function", location);
 512       result_type
 513         = cp_build_qualified_type (void_type_node,
 514                                    (cp_type_quals (TREE_TYPE (t1))
 515                                     | cp_type_quals (TREE_TYPE (t2))));
 516       result_type = build_pointer_type (result_type);
 517       /* Merge the attributes.  */
 518       attributes = (*targetm.merge_type_attributes) (t1, t2);
 519       return build_type_attribute_variant (result_type, attributes);
 520     }
 521
 522   /* [expr.eq] permits the application of a pointer conversion to
 523      bring the pointers to a common type.  */
 524   if (TREE_CODE (t1) == POINTER_TYPE && TREE_CODE (t2) == POINTER_TYPE
 525       && CLASS_TYPE_P (TREE_TYPE (t1))
 526       && CLASS_TYPE_P (TREE_TYPE (t2))
 527       && !same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (t1),
 528                                                      TREE_TYPE (t2)))
 529     {
 530       class1 = TREE_TYPE (t1);
 531       class2 = TREE_TYPE (t2);
 532
 533       if (DERIVED_FROM_P (class1, class2))
 534         t2 = (build_pointer_type
 535               (cp_build_qualified_type (class1, TYPE_QUALS (class2))));
 536       else if (DERIVED_FROM_P (class2, class1))
 537         t1 = (build_pointer_type
 538               (cp_build_qualified_type (class2, TYPE_QUALS (class1))));
 539       else
 540         {
 541           error ("%s between distinct pointer types `%T' and `%T' "
 542                  "lacks a cast", location, t1, t2);
 543           return error_mark_node;
 544         }
 545     }
 546   /* [expr.eq] permits the application of a pointer-to-member
 547      conversion to change the class type of one of the types.  */
 548   else if (TYPE_PTR_TO_MEMBER_P (t1)
 549            && !same_type_p (TYPE_PTRMEM_CLASS_TYPE (t1),
 550                             TYPE_PTRMEM_CLASS_TYPE (t2)))
 551     {
 552       class1 = TYPE_PTRMEM_CLASS_TYPE (t1);
 553       class2 = TYPE_PTRMEM_CLASS_TYPE (t2);
 554
 555       if (DERIVED_FROM_P (class1, class2))
 556         t1 = build_ptrmem_type (class2, TYPE_PTRMEM_POINTED_TO_TYPE (t1));
 557       else if (DERIVED_FROM_P (class2, class1))
 558         t2 = build_ptrmem_type (class1, TYPE_PTRMEM_POINTED_TO_TYPE (t2));
 559       else
 560         {
 561           error ("%s between distinct pointer-to-member types `%T' and `%T' "
 562                  "lacks a cast", location, t1, t2);
 563           return error_mark_node;
 564         }
 565     }
 566
 567   return composite_pointer_type_r (t1, t2, location);
 568 }
 569
 570 /* Return the merged type of two types.
 571    We assume that comptypes has already been done and returned 1;
 572    if that isn't so, this may crash.
 573
 574    This just combines attributes and default arguments; any other
 575    differences would cause the two types to compare unalike.  */
 576
 577 tree
 578 merge_types (tree t1, tree t2)
 579 {
 580   enum tree_code code1;
 581   enum tree_code code2;
 582   tree attributes;
 583
 584   /* Save time if the two types are the same.  */
 585   if (t1 == t2)
 586     return t1;
 587   if (original_type (t1) == original_type (t2))
 588     return t1;
 589
 590   /* If one type is nonsense, use the other.  */
 591   if (t1 == error_mark_node)
 592     return t2;
 593   if (t2 == error_mark_node)
 594     return t1;
 595
 596   /* Merge the attributes.  */
 597   attributes = (*targetm.merge_type_attributes) (t1, t2);
 598
 599   if (TYPE_PTRMEMFUNC_P (t1))
 600     t1 = TYPE_PTRMEMFUNC_FN_TYPE (t1);
 601   if (TYPE_PTRMEMFUNC_P (t2))
 602     t2 = TYPE_PTRMEMFUNC_FN_TYPE (t2);
 603
 604   code1 = TREE_CODE (t1);
 605   code2 = TREE_CODE (t2);
 606
 607   switch (code1)
 608     {
 609     case POINTER_TYPE:
 610     case REFERENCE_TYPE:
 611       /* For two pointers, do this recursively on the target type.  */
 612       {
 613         tree target = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
 614         int quals = cp_type_quals (t1);
 615
 616         if (code1 == POINTER_TYPE)
 617           t1 = build_pointer_type (target);
 618         else
 619           t1 = build_reference_type (target);
 620         t1 = build_type_attribute_variant (t1, attributes);
 621         t1 = cp_build_qualified_type (t1, quals);
 622
 623         if (TREE_CODE (target) == METHOD_TYPE)
 624           t1 = build_ptrmemfunc_type (t1);
 625
 626         return t1;
 627       }
 628
 629     case OFFSET_TYPE:
 630       {
 631         int quals;
 632         tree pointee;
 633         quals = cp_type_quals (t1);
 634         pointee = merge_types (TYPE_PTRMEM_POINTED_TO_TYPE (t1),
 635                                TYPE_PTRMEM_POINTED_TO_TYPE (t2));
 636         t1 = build_ptrmem_type (TYPE_PTRMEM_CLASS_TYPE (t1),
 637                                 pointee);
 638         t1 = cp_build_qualified_type (t1, quals);
 639         break;
 640       }
 641
 642     case ARRAY_TYPE:
 643       {
 644         tree elt = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
 645         /* Save space: see if the result is identical to one of the args.  */
 646         if (elt == TREE_TYPE (t1) && TYPE_DOMAIN (t1))
 647           return build_type_attribute_variant (t1, attributes);
 648         if (elt == TREE_TYPE (t2) && TYPE_DOMAIN (t2))
 649           return build_type_attribute_variant (t2, attributes);
 650         /* Merge the element types, and have a size if either arg has one.  */
 651         t1 = build_cplus_array_type
 652           (elt, TYPE_DOMAIN (TYPE_DOMAIN (t1) ? t1 : t2));
 653         break;
 654       }
 655
 656     case FUNCTION_TYPE:
 657       /* Function types: prefer the one that specified arg types.
 658          If both do, merge the arg types.  Also merge the return types.  */
 659       {
 660         tree valtype = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
 661         tree p1 = TYPE_ARG_TYPES (t1);
 662         tree p2 = TYPE_ARG_TYPES (t2);
 663         tree rval, raises;
 664
 665         /* Save space: see if the result is identical to one of the args.  */
 666         if (valtype == TREE_TYPE (t1) && ! p2)
 667           return cp_build_type_attribute_variant (t1, attributes);
 668         if (valtype == TREE_TYPE (t2) && ! p1)
 669           return cp_build_type_attribute_variant (t2, attributes);
 670
 671         /* Simple way if one arg fails to specify argument types.  */
 672         if (p1 == NULL_TREE || TREE_VALUE (p1) == void_type_node)
 673           {
 674             rval = build_function_type (valtype, p2);
 675             if ((raises = TYPE_RAISES_EXCEPTIONS (t2)))
 676               rval = build_exception_variant (rval, raises);
 677             return cp_build_type_attribute_variant (rval, attributes);
 678           }
 679         raises = TYPE_RAISES_EXCEPTIONS (t1);
 680         if (p2 == NULL_TREE || TREE_VALUE (p2) == void_type_node)
 681           {
 682             rval = build_function_type (valtype, p1);
 683             if (raises)
 684               rval = build_exception_variant (rval, raises);
 685             return cp_build_type_attribute_variant (rval, attributes);
 686           }
 687
 688         rval = build_function_type (valtype, commonparms (p1, p2));
 689         t1 = build_exception_variant (rval, raises);
 690         break;
 691       }
 692
 693     case METHOD_TYPE:
 694       {
 695         /* Get this value the long way, since TYPE_METHOD_BASETYPE
 696            is just the main variant of this.  */
 697         tree basetype = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (t2)));
 698         tree raises = TYPE_RAISES_EXCEPTIONS (t1);
 699         tree t3;
 700
 701         /* If this was a member function type, get back to the
 702            original type of type member function (i.e., without
 703            the class instance variable up front.  */
 704         t1 = build_function_type (TREE_TYPE (t1),
 705                                   TREE_CHAIN (TYPE_ARG_TYPES (t1)));
 706         t2 = build_function_type (TREE_TYPE (t2),
 707                                   TREE_CHAIN (TYPE_ARG_TYPES (t2)));
 708         t3 = merge_types (t1, t2);
 709         t3 = build_method_type_directly (basetype, TREE_TYPE (t3),
 710                                          TYPE_ARG_TYPES (t3));
 711         t1 = build_exception_variant (t3, raises);
 712         break;
 713       }
 714
 715     case TYPENAME_TYPE:
 716       /* There is no need to merge attributes into a TYPENAME_TYPE.
 717          When the type is instantiated it will have whatever
 718          attributes result from the instantiation.  */
 719       return t1;
 720
 721     default:;
 722     }
 723   return cp_build_type_attribute_variant (t1, attributes);
 724 }
 725
 726 /* Return the common type of two types.
 727    We assume that comptypes has already been done and returned 1;
 728    if that isn't so, this may crash.
 729
 730    This is the type for the result of most arithmetic operations
 731    if the operands have the given two types.  */
 732
 733 tree
 734 common_type (tree t1, tree t2)
 735 {
 736   enum tree_code code1;
 737   enum tree_code code2;
 738
 739   /* If one type is nonsense, bail.  */
 740   if (t1 == error_mark_node || t2 == error_mark_node)
 741     return error_mark_node;
 742
 743   code1 = TREE_CODE (t1);
 744   code2 = TREE_CODE (t2);
 745
 746   if ((ARITHMETIC_TYPE_P (t1) || code1 == ENUMERAL_TYPE
 747        || code1 == COMPLEX_TYPE)
 748       && (ARITHMETIC_TYPE_P (t2) || code2 == ENUMERAL_TYPE
 749           || code2 == COMPLEX_TYPE))
 750     return type_after_usual_arithmetic_conversions (t1, t2);
 751
 752   else if ((TYPE_PTR_P (t1) && TYPE_PTR_P (t2))
 753            || (TYPE_PTRMEM_P (t1) && TYPE_PTRMEM_P (t2))
 754            || (TYPE_PTRMEMFUNC_P (t1) && TYPE_PTRMEMFUNC_P (t2)))
 755     return composite_pointer_type (t1, t2, error_mark_node, error_mark_node,
 756                                    "conversion");
 757   else
 758     abort ();
 759 }
 760 \f
 761 /* Compare two exception specifier types for exactness or subsetness, if
 762    allowed. Returns false for mismatch, true for match (same, or
 763    derived and !exact).
 764
 765    [except.spec] "If a class X ... objects of class X or any class publicly
 766    and unambiguously derived from X. Similarly, if a pointer type Y * ...
 767    exceptions of type Y * or that are pointers to any type publicly and
 768    unambiguously derived from Y. Otherwise a function only allows exceptions
 769    that have the same type ..."
 770    This does not mention cv qualifiers and is different to what throw
 771    [except.throw] and catch [except.catch] will do. They will ignore the
 772    top level cv qualifiers, and allow qualifiers in the pointer to class
 773    example.
 774
 775    We implement the letter of the standard.  */
 776
 777 static bool
 778 comp_except_types (tree a, tree b, bool exact)
 779 {
 780   if (same_type_p (a, b))
 781     return true;
 782   else if (!exact)
 783     {
 784       if (cp_type_quals (a) || cp_type_quals (b))
 785         return false;
 786
 787       if (TREE_CODE (a) == POINTER_TYPE
 788           && TREE_CODE (b) == POINTER_TYPE)
 789         {
 790           a = TREE_TYPE (a);
 791           b = TREE_TYPE (b);
 792           if (cp_type_quals (a) || cp_type_quals (b))
 793             return false;
 794         }
 795
 796       if (TREE_CODE (a) != RECORD_TYPE
 797           || TREE_CODE (b) != RECORD_TYPE)
 798         return false;
 799
 800       if (ACCESSIBLY_UNIQUELY_DERIVED_P (a, b))
 801         return true;
 802     }
 803   return false;
 804 }
 805
 806 /* Return true if TYPE1 and TYPE2 are equivalent exception specifiers.
 807    If EXACT is false, T2 can be stricter than T1 (according to 15.4/7),
 808    otherwise it must be exact. Exception lists are unordered, but
 809    we've already filtered out duplicates. Most lists will be in order,
 810    we should try to make use of that.  */
 811
 812 bool
 813 comp_except_specs (tree t1, tree t2, bool exact)
 814 {
 815   tree probe;
 816   tree base;
 817   int  length = 0;
 818
 819   if (t1 == t2)
 820     return true;
 821
 822   if (t1 == NULL_TREE)              /* T1 is ...  */
 823     return t2 == NULL_TREE || !exact;
 824   if (!TREE_VALUE (t1)) /* t1 is EMPTY */
 825     return t2 != NULL_TREE && !TREE_VALUE (t2);
 826   if (t2 == NULL_TREE)              /* T2 is ...  */
 827     return false;
 828   if (TREE_VALUE (t1) && !TREE_VALUE (t2)) /* T2 is EMPTY, T1 is not */
 829     return !exact;
 830
 831   /* Neither set is ... or EMPTY, make sure each part of T2 is in T1.
 832      Count how many we find, to determine exactness. For exact matching and
 833      ordered T1, T2, this is an O(n) operation, otherwise its worst case is
 834      O(nm).  */
 835   for (base = t1; t2 != NULL_TREE; t2 = TREE_CHAIN (t2))
 836     {
 837       for (probe = base; probe != NULL_TREE; probe = TREE_CHAIN (probe))
 838         {
 839           tree a = TREE_VALUE (probe);
 840           tree b = TREE_VALUE (t2);
 841
 842           if (comp_except_types (a, b, exact))
 843             {
 844               if (probe == base && exact)
 845                 base = TREE_CHAIN (probe);
 846               length++;
 847               break;
 848             }
 849         }
 850       if (probe == NULL_TREE)
 851         return false;
 852     }
 853   return !exact || base == NULL_TREE || length == list_length (t1);
 854 }
 855
 856 /* Compare the array types T1 and T2.  ALLOW_REDECLARATION is true if
 857    [] can match [size].  */
 858
 859 static bool
 860 comp_array_types (tree t1, tree t2, bool allow_redeclaration)
 861 {
 862   tree d1;
 863   tree d2;
 864   tree max1, max2;
 865
 866   if (t1 == t2)
 867     return true;
 868
 869   /* The type of the array elements must be the same.  */
 870   if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
 871     return false;
 872
 873   d1 = TYPE_DOMAIN (t1);
 874   d2 = TYPE_DOMAIN (t2);
 875
 876   if (d1 == d2)
 877     return true;
 878
 879   /* If one of the arrays is dimensionless, and the other has a
 880      dimension, they are of different types.  However, it is valid to
 881      write:
 882
 883        extern int a[];
 884        int a[3];
 885
 886      by [basic.link]:
 887
 888        declarations for an array object can specify
 889        array types that differ by the presence or absence of a major
 890        array bound (_dcl.array_).  */
 891   if (!d1 || !d2)
 892     return allow_redeclaration;
 893
 894   /* Check that the dimensions are the same.  */
 895
 896   if (!cp_tree_equal (TYPE_MIN_VALUE (d1), TYPE_MIN_VALUE (d2)))
 897     return false;
 898   max1 = TYPE_MAX_VALUE (d1);
 899   max2 = TYPE_MAX_VALUE (d2);
 900   if (processing_template_decl && !abi_version_at_least (2)
 901       && !value_dependent_expression_p (max1)
 902       && !value_dependent_expression_p (max2))
 903     {
 904       /* With abi-1 we do not fold non-dependent array bounds, (and
 905          consequently mangle them incorrectly).  We must therefore
 906          fold them here, to verify the domains have the same
 907          value.  */
 908       max1 = fold (max1);
 909       max2 = fold (max2);
 910     }
 911
 912   if (!cp_tree_equal (max1, max2))
 913     return false;
 914
 915   return true;
 916 }
 917
 918 /* Return true if T1 and T2 are related as allowed by STRICT.  STRICT
 919    is a bitwise-or of the COMPARE_* flags.  */
 920
 921 bool
 922 comptypes (tree t1, tree t2, int strict)
 923 {
 924   if (t1 == t2)
 925     return true;
 926
 927   /* Suppress errors caused by previously reported errors.  */
 928   if (t1 == error_mark_node || t2 == error_mark_node)
 929     return false;
 930
 931   my_friendly_assert (TYPE_P (t1) && TYPE_P (t2), 20030623);
 932
 933   /* TYPENAME_TYPEs should be resolved if the qualifying scope is the
 934      current instantiation.  */
 935   if (TREE_CODE (t1) == TYPENAME_TYPE)
 936     {
 937       tree resolved = resolve_typename_type (t1, /*only_current_p=*/true);
 938
 939       if (resolved != error_mark_node)
 940         t1 = resolved;
 941     }
 942
 943   if (TREE_CODE (t2) == TYPENAME_TYPE)
 944     {
 945       tree resolved = resolve_typename_type (t2, /*only_current_p=*/true);
 946
 947       if (resolved != error_mark_node)
 948         t2 = resolved;
 949     }
 950
 951   /* If either type is the internal version of sizetype, use the
 952      language version.  */
 953   if (TREE_CODE (t1) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t1)
 954       && TYPE_ORIG_SIZE_TYPE (t1))
 955     t1 = TYPE_ORIG_SIZE_TYPE (t1);
 956
 957   if (TREE_CODE (t2) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t2)
 958       && TYPE_ORIG_SIZE_TYPE (t2))
 959     t2 = TYPE_ORIG_SIZE_TYPE (t2);
 960
 961   if (TYPE_PTRMEMFUNC_P (t1))
 962     t1 = TYPE_PTRMEMFUNC_FN_TYPE (t1);
 963   if (TYPE_PTRMEMFUNC_P (t2))
 964     t2 = TYPE_PTRMEMFUNC_FN_TYPE (t2);
 965
 966   /* Different classes of types can't be compatible.  */
 967   if (TREE_CODE (t1) != TREE_CODE (t2))
 968     return false;
 969
 970   /* Qualifiers must match.  For array types, we will check when we
 971      recur on the array element types.  */
 972   if (TREE_CODE (t1) != ARRAY_TYPE
 973       && TYPE_QUALS (t1) != TYPE_QUALS (t2))
 974     return false;
 975   if (TYPE_FOR_JAVA (t1) != TYPE_FOR_JAVA (t2))
 976     return false;
 977
 978   /* Allow for two different type nodes which have essentially the same
 979      definition.  Note that we already checked for equality of the type
 980      qualifiers (just above).  */
 981
 982   if (TREE_CODE (t1) != ARRAY_TYPE
 983       && TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
 984     return true;
 985
 986   if (!(*targetm.comp_type_attributes) (t1, t2))
 987     return false;
 988
 989   switch (TREE_CODE (t1))
 990     {
 991     case TEMPLATE_TEMPLATE_PARM:
 992     case BOUND_TEMPLATE_TEMPLATE_PARM:
 993       if (TEMPLATE_TYPE_IDX (t1) != TEMPLATE_TYPE_IDX (t2)
 994           || TEMPLATE_TYPE_LEVEL (t1) != TEMPLATE_TYPE_LEVEL (t2))
 995         return false;
 996       if (!comp_template_parms
 997           (DECL_TEMPLATE_PARMS (TEMPLATE_TEMPLATE_PARM_TEMPLATE_DECL (t1)),
 998            DECL_TEMPLATE_PARMS (TEMPLATE_TEMPLATE_PARM_TEMPLATE_DECL (t2))))
 999         return false;
1000       if (TREE_CODE (t1) == TEMPLATE_TEMPLATE_PARM)
1001         return true;
1002       /* Don't check inheritance.  */
1003       strict = COMPARE_STRICT;
1004       /* Fall through.  */
1005
1006     case RECORD_TYPE:
1007     case UNION_TYPE:
1008       if (TYPE_TEMPLATE_INFO (t1) && TYPE_TEMPLATE_INFO (t2)
1009           && (TYPE_TI_TEMPLATE (t1) == TYPE_TI_TEMPLATE (t2)
1010               || TREE_CODE (t1) == BOUND_TEMPLATE_TEMPLATE_PARM)
1011           && comp_template_args (TYPE_TI_ARGS (t1), TYPE_TI_ARGS (t2)))
1012         return true;
1013
1014       if ((strict & COMPARE_BASE) && DERIVED_FROM_P (t1, t2))
1015         return true;
1016       else if ((strict & COMPARE_DERIVED) && DERIVED_FROM_P (t2, t1))
1017         return true;
1018
1019       return false;
1020
1021     case OFFSET_TYPE:
1022       if (!comptypes (TYPE_OFFSET_BASETYPE (t1), TYPE_OFFSET_BASETYPE (t2),
1023                       strict & ~COMPARE_REDECLARATION))
1024         return false;
1025       /* Fall through.  */
1026
1027     case POINTER_TYPE:
1028     case REFERENCE_TYPE:
1029       return same_type_p (TREE_TYPE (t1), TREE_TYPE (t2));
1030
1031     case METHOD_TYPE:
1032     case FUNCTION_TYPE:
1033       if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
1034         return false;
1035       return compparms (TYPE_ARG_TYPES (t1), TYPE_ARG_TYPES (t2));
1036
1037     case ARRAY_TYPE:
1038       /* Target types must match incl. qualifiers.  */
1039       return comp_array_types (t1, t2, !!(strict & COMPARE_REDECLARATION));
1040
1041     case TEMPLATE_TYPE_PARM:
1042       return (TEMPLATE_TYPE_IDX (t1) == TEMPLATE_TYPE_IDX (t2)
1043               && TEMPLATE_TYPE_LEVEL (t1) == TEMPLATE_TYPE_LEVEL (t2));
1044
1045     case TYPENAME_TYPE:
1046       if (!cp_tree_equal (TYPENAME_TYPE_FULLNAME (t1),
1047                           TYPENAME_TYPE_FULLNAME (t2)))
1048         return false;
1049       return same_type_p (TYPE_CONTEXT (t1), TYPE_CONTEXT (t2));
1050
1051     case UNBOUND_CLASS_TEMPLATE:
1052       if (!cp_tree_equal (TYPE_IDENTIFIER (t1), TYPE_IDENTIFIER (t2)))
1053         return false;
1054       return same_type_p (TYPE_CONTEXT (t1), TYPE_CONTEXT (t2));
1055
1056     case COMPLEX_TYPE:
1057       return same_type_p (TREE_TYPE (t1), TREE_TYPE (t2));
1058
1059     case VECTOR_TYPE:
1060       return TYPE_VECTOR_SUBPARTS (t1) == TYPE_VECTOR_SUBPARTS (t2)
1061              && same_type_p (TREE_TYPE (t1), TREE_TYPE (t2));
1062       break;
1063
1064     default:
1065       break;
1066     }
1067   return false;
1068 }
1069
1070 /* Returns 1 if TYPE1 is at least as qualified as TYPE2.  */
1071
1072 bool
1073 at_least_as_qualified_p (tree type1, tree type2)
1074 {
1075   int q1 = cp_type_quals (type1);
1076   int q2 = cp_type_quals (type2);
1077
1078   /* All qualifiers for TYPE2 must also appear in TYPE1.  */
1079   return (q1 & q2) == q2;
1080 }
1081
1082 /* Returns 1 if TYPE1 is more qualified than TYPE2.  */
1083
1084 bool
1085 more_qualified_p (tree type1, tree type2)
1086 {
1087   int q1 = cp_type_quals (type1);
1088   int q2 = cp_type_quals (type2);
1089
1090   return q1 != q2 && (q1 & q2) == q2;
1091 }
1092
1093 /* Returns 1 if TYPE1 is more cv-qualified than TYPE2, -1 if TYPE2 is
1094    more cv-qualified that TYPE1, and 0 otherwise.  */
1095
1096 int
1097 comp_cv_qualification (tree type1, tree type2)
1098 {
1099   int q1 = cp_type_quals (type1);
1100   int q2 = cp_type_quals (type2);
1101
1102   if (q1 == q2)
1103     return 0;
1104
1105   if ((q1 & q2) == q2)
1106     return 1;
1107   else if ((q1 & q2) == q1)
1108     return -1;
1109
1110   return 0;
1111 }
1112
1113 /* Returns 1 if the cv-qualification signature of TYPE1 is a proper
1114    subset of the cv-qualification signature of TYPE2, and the types
1115    are similar.  Returns -1 if the other way 'round, and 0 otherwise.  */
1116
1117 int
1118 comp_cv_qual_signature (tree type1, tree type2)
1119 {
1120   if (comp_ptr_ttypes_real (type2, type1, -1))
1121     return 1;
1122   else if (comp_ptr_ttypes_real (type1, type2, -1))
1123     return -1;
1124   else
1125     return 0;
1126 }
1127
1128 /* If two types share a common base type, return that basetype.
1129    If there is not a unique most-derived base type, this function
1130    returns ERROR_MARK_NODE.  */
1131
1132 static tree
1133 common_base_type (tree tt1, tree tt2)
1134 {
1135   tree best = NULL_TREE;
1136   int i;
1137
1138   /* If one is a baseclass of another, that's good enough.  */
1139   if (UNIQUELY_DERIVED_FROM_P (tt1, tt2))
1140     return tt1;
1141   if (UNIQUELY_DERIVED_FROM_P (tt2, tt1))
1142     return tt2;
1143
1144   /* Otherwise, try to find a unique baseclass of TT1
1145      that is shared by TT2, and follow that down.  */
1146   for (i = BINFO_N_BASE_BINFOS (TYPE_BINFO (tt1))-1; i >= 0; i--)
1147     {
1148       tree basetype = BINFO_TYPE (BINFO_BASE_BINFO (TYPE_BINFO (tt1), i));
1149       tree trial = common_base_type (basetype, tt2);
1150
1151       if (trial)
1152         {
1153           if (trial == error_mark_node)
1154             return trial;
1155           if (best == NULL_TREE)
1156             best = trial;
1157           else if (best != trial)
1158             return error_mark_node;
1159         }
1160     }
1161
1162   /* Same for TT2.  */
1163   for (i = BINFO_N_BASE_BINFOS (TYPE_BINFO (tt2))-1; i >= 0; i--)
1164     {
1165       tree basetype = BINFO_TYPE (BINFO_BASE_BINFO (TYPE_BINFO (tt2), i));
1166       tree trial = common_base_type (tt1, basetype);
1167
1168       if (trial)
1169         {
1170           if (trial == error_mark_node)
1171             return trial;
1172           if (best == NULL_TREE)
1173             best = trial;
1174           else if (best != trial)
1175             return error_mark_node;
1176         }
1177     }
1178   return best;
1179 }
1180 \f
1181 /* Subroutines of `comptypes'.  */
1182
1183 /* Return true if two parameter type lists PARMS1 and PARMS2 are
1184    equivalent in the sense that functions with those parameter types
1185    can have equivalent types.  The two lists must be equivalent,
1186    element by element.  */
1187
1188 bool
1189 compparms (tree parms1, tree parms2)
1190 {
1191   tree t1, t2;
1192
1193   /* An unspecified parmlist matches any specified parmlist
1194      whose argument types don't need default promotions.  */
1195
1196   for (t1 = parms1, t2 = parms2;
1197        t1 || t2;
1198        t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2))
1199     {
1200       /* If one parmlist is shorter than the other,
1201          they fail to match.  */
1202       if (!t1 || !t2)
1203         return false;
1204       if (!same_type_p (TREE_VALUE (t1), TREE_VALUE (t2)))
1205         return false;
1206     }
1207   return true;
1208 }
1209
1210 \f
1211 /* Process a sizeof or alignof expression where the operand is a
1212    type.  */
1213
1214 tree
1215 cxx_sizeof_or_alignof_type (tree type, enum tree_code op, bool complain)
1216 {
1217   enum tree_code type_code;
1218   tree value;
1219   const char *op_name;
1220
1221   my_friendly_assert (op == SIZEOF_EXPR || op == ALIGNOF_EXPR, 20020720);
1222   if (type == error_mark_node)
1223     return error_mark_node;
1224
1225   if (processing_template_decl)
1226     {
1227       value = build_min (op, size_type_node, type);
1228       TREE_READONLY (value) = 1;
1229       return value;
1230     }
1231
1232   op_name = operator_name_info[(int) op].name;
1233
1234   type = non_reference (type);
1235   type_code = TREE_CODE (type);
1236
1237   if (type_code == METHOD_TYPE)
1238     {
1239       if (complain && (pedantic || warn_pointer_arith))
1240         pedwarn ("invalid application of `%s' to a member function", op_name);
1241       value = size_one_node;
1242     }
1243   else
1244     value = c_sizeof_or_alignof_type (complete_type (type), op, complain);
1245
1246   return value;
1247 }
1248
1249 /* Process a sizeof or alignof expression where the operand is an
1250    expression.  */
1251
1252 tree
1253 cxx_sizeof_or_alignof_expr (tree e, enum tree_code op)
1254 {
1255   const char *op_name = operator_name_info[(int) op].name;
1256
1257   if (e == error_mark_node)
1258     return error_mark_node;
1259
1260   if (processing_template_decl)
1261     {
1262       e = build_min (op, size_type_node, e);
1263       TREE_SIDE_EFFECTS (e) = 0;
1264       TREE_READONLY (e) = 1;
1265
1266       return e;
1267     }
1268
1269   if (TREE_CODE (e) == COMPONENT_REF
1270       && TREE_CODE (TREE_OPERAND (e, 1)) == FIELD_DECL
1271       && DECL_C_BIT_FIELD (TREE_OPERAND (e, 1)))
1272     {
1273       error ("invalid application of `%s' to a bit-field", op_name);
1274       e = char_type_node;
1275     }
1276   else if (is_overloaded_fn (e))
1277     {
1278       pedwarn ("ISO C++ forbids applying `%s' to an expression of function type", op_name);
1279       e = char_type_node;
1280     }
1281   else if (type_unknown_p (e))
1282     {
1283       cxx_incomplete_type_error (e, TREE_TYPE (e));
1284       e = char_type_node;
1285     }
1286   else
1287     e = TREE_TYPE (e);
1288
1289   return cxx_sizeof_or_alignof_type (e, op, true);
1290 }
1291
1292 \f
1293 /* EXPR is being used in a context that is not a function call.
1294    Enforce:
1295
1296      [expr.ref]
1297
1298      The expression can be used only as the left-hand operand of a
1299      member function call.
1300
1301      [expr.mptr.operator]
1302
1303      If the result of .* or ->* is a function, then that result can be
1304      used only as the operand for the function call operator ().
1305
1306    by issuing an error message if appropriate.  Returns true iff EXPR
1307    violates these rules.  */
1308
1309 bool
1310 invalid_nonstatic_memfn_p (tree expr)
1311 {
1312   if (TREE_CODE (TREE_TYPE (expr)) == METHOD_TYPE)
1313     {
1314       error ("invalid use of non-static member function");
1315       return true;
1316     }
1317   return false;
1318 }
1319
1320 /* Perform the conversions in [expr] that apply when an lvalue appears
1321    in an rvalue context: the lvalue-to-rvalue, array-to-pointer, and
1322    function-to-pointer conversions.
1323
1324    In addition manifest constants are replaced by their values.  */
1325
1326 tree
1327 decay_conversion (tree exp)
1328 {
1329   tree type;
1330   enum tree_code code;
1331
1332   type = TREE_TYPE (exp);
1333   code = TREE_CODE (type);
1334
1335   if (code == REFERENCE_TYPE)
1336     {
1337       exp = convert_from_reference (exp);
1338       type = TREE_TYPE (exp);
1339       code = TREE_CODE (type);
1340     }
1341
1342   if (type == error_mark_node)
1343     return error_mark_node;
1344
1345   if (type_unknown_p (exp))
1346     {
1347       cxx_incomplete_type_error (exp, TREE_TYPE (exp));
1348       return error_mark_node;
1349     }
1350
1351   /* Constants can be used directly unless they're not loadable.  */
1352   if (TREE_CODE (exp) == CONST_DECL)
1353     exp = DECL_INITIAL (exp);
1354   /* Replace a nonvolatile const static variable with its value.  We
1355      don't do this for arrays, though; we want the address of the
1356      first element of the array, not the address of the first element
1357      of its initializing constant.  */
1358   else if (code != ARRAY_TYPE)
1359     {
1360       exp = decl_constant_value (exp);
1361       type = TREE_TYPE (exp);
1362     }
1363
1364   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
1365      Leave such NOP_EXPRs, since RHS is being used in non-lvalue context.  */
1366
1367   if (code == VOID_TYPE)
1368     {
1369       error ("void value not ignored as it ought to be");
1370       return error_mark_node;
1371     }
1372   if (invalid_nonstatic_memfn_p (exp))
1373     return error_mark_node;
1374   if (code == FUNCTION_TYPE || is_overloaded_fn (exp))
1375     return build_unary_op (ADDR_EXPR, exp, 0);
1376   if (code == ARRAY_TYPE)
1377     {
1378       tree adr;
1379       tree ptrtype;
1380
1381       if (TREE_CODE (exp) == INDIRECT_REF)
1382         return build_nop (build_pointer_type (TREE_TYPE (type)),
1383                           TREE_OPERAND (exp, 0));
1384
1385       if (TREE_CODE (exp) == COMPOUND_EXPR)
1386         {
1387           tree op1 = decay_conversion (TREE_OPERAND (exp, 1));
1388           return build (COMPOUND_EXPR, TREE_TYPE (op1),
1389                         TREE_OPERAND (exp, 0), op1);
1390         }
1391
1392       if (!lvalue_p (exp)
1393           && ! (TREE_CODE (exp) == CONSTRUCTOR && TREE_STATIC (exp)))
1394         {
1395           error ("invalid use of non-lvalue array");
1396           return error_mark_node;
1397         }
1398
1399       ptrtype = build_pointer_type (TREE_TYPE (type));
1400
1401       if (TREE_CODE (exp) == VAR_DECL)
1402         {
1403           if (!cxx_mark_addressable (exp))
1404             return error_mark_node;
1405           adr = build_nop (ptrtype, build_address (exp));
1406           return adr;
1407         }
1408       /* This way is better for a COMPONENT_REF since it can
1409          simplify the offset for a component.  */
1410       adr = build_unary_op (ADDR_EXPR, exp, 1);
1411       return cp_convert (ptrtype, adr);
1412     }
1413
1414   /* [basic.lval]: Class rvalues can have cv-qualified types; non-class
1415      rvalues always have cv-unqualified types.  */
1416   if (! CLASS_TYPE_P (type))
1417     exp = cp_convert (TYPE_MAIN_VARIANT (type), exp);
1418
1419   return exp;
1420 }
1421
1422 tree
1423 default_conversion (tree exp)
1424 {
1425   exp = decay_conversion (exp);
1426
1427   if (INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (exp)))
1428     exp = perform_integral_promotions (exp);
1429
1430   return exp;
1431 }
1432
1433 /* EXPR is an expression with an integral or enumeration type.
1434    Perform the integral promotions in [conv.prom], and return the
1435    converted value.  */
1436
1437 tree
1438 perform_integral_promotions (tree expr)
1439 {
1440   tree type;
1441   tree promoted_type;
1442
1443   type = TREE_TYPE (expr);
1444   my_friendly_assert (INTEGRAL_OR_ENUMERATION_TYPE_P (type), 20030703);
1445   promoted_type = type_promotes_to (type);
1446   if (type != promoted_type)
1447     expr = cp_convert (promoted_type, expr);
1448   return expr;
1449 }
1450
1451 /* Take the address of an inline function without setting TREE_ADDRESSABLE
1452    or TREE_USED.  */
1453
1454 tree
1455 inline_conversion (tree exp)
1456 {
1457   if (TREE_CODE (exp) == FUNCTION_DECL)
1458     exp = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (exp)), exp);
1459
1460   return exp;
1461 }
1462
1463 /* Returns nonzero iff exp is a STRING_CST or the result of applying
1464    decay_conversion to one.  */
1465
1466 int
1467 string_conv_p (tree totype, tree exp, int warn)
1468 {
1469   tree t;
1470
1471   if (! flag_const_strings || TREE_CODE (totype) != POINTER_TYPE)
1472     return 0;
1473
1474   t = TREE_TYPE (totype);
1475   if (!same_type_p (t, char_type_node)
1476       && !same_type_p (t, wchar_type_node))
1477     return 0;
1478
1479   if (TREE_CODE (exp) == STRING_CST)
1480     {
1481       /* Make sure that we don't try to convert between char and wchar_t.  */
1482       if (!same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (exp))), t))
1483         return 0;
1484     }
1485   else
1486     {
1487       /* Is this a string constant which has decayed to 'const char *'?  */
1488       t = build_pointer_type (build_qualified_type (t, TYPE_QUAL_CONST));
1489       if (!same_type_p (TREE_TYPE (exp), t))
1490         return 0;
1491       STRIP_NOPS (exp);
1492       if (TREE_CODE (exp) != ADDR_EXPR
1493           || TREE_CODE (TREE_OPERAND (exp, 0)) != STRING_CST)
1494         return 0;
1495     }
1496
1497   /* This warning is not very useful, as it complains about printf.  */
1498   if (warn && warn_write_strings)
1499     warning ("deprecated conversion from string constant to `%T'", totype);
1500
1501   return 1;
1502 }
1503
1504 /* Given a COND_EXPR, MIN_EXPR, or MAX_EXPR in T, return it in a form that we
1505    can, for example, use as an lvalue.  This code used to be in
1506    unary_complex_lvalue, but we needed it to deal with `a = (d == c) ? b : c'
1507    expressions, where we're dealing with aggregates.  But now it's again only
1508    called from unary_complex_lvalue.  The case (in particular) that led to
1509    this was with CODE == ADDR_EXPR, since it's not an lvalue when we'd
1510    get it there.  */
1511
1512 static tree
1513 rationalize_conditional_expr (enum tree_code code, tree t)
1514 {
1515   /* For MIN_EXPR or MAX_EXPR, fold-const.c has arranged things so that
1516      the first operand is always the one to be used if both operands
1517      are equal, so we know what conditional expression this used to be.  */
1518   if (TREE_CODE (t) == MIN_EXPR || TREE_CODE (t) == MAX_EXPR)
1519     {
1520       return
1521         build_conditional_expr (build_x_binary_op ((TREE_CODE (t) == MIN_EXPR
1522                                                     ? LE_EXPR : GE_EXPR),
1523                                                    TREE_OPERAND (t, 0),
1524                                                    TREE_OPERAND (t, 1),
1525                                                    /*overloaded_p=*/NULL),
1526                             build_unary_op (code, TREE_OPERAND (t, 0), 0),
1527                             build_unary_op (code, TREE_OPERAND (t, 1), 0));
1528     }
1529
1530   return
1531     build_conditional_expr (TREE_OPERAND (t, 0),
1532                             build_unary_op (code, TREE_OPERAND (t, 1), 0),
1533                             build_unary_op (code, TREE_OPERAND (t, 2), 0));
1534 }
1535
1536 /* Given the TYPE of an anonymous union field inside T, return the
1537    FIELD_DECL for the field.  If not found return NULL_TREE.  Because
1538    anonymous unions can nest, we must also search all anonymous unions
1539    that are directly reachable.  */
1540
1541 tree
1542 lookup_anon_field (tree t, tree type)
1543 {
1544   tree field;
1545
1546   for (field = TYPE_FIELDS (t); field; field = TREE_CHAIN (field))
1547     {
1548       if (TREE_STATIC (field))
1549         continue;
1550       if (TREE_CODE (field) != FIELD_DECL || DECL_ARTIFICIAL (field))
1551         continue;
1552
1553       /* If we find it directly, return the field.  */
1554       if (DECL_NAME (field) == NULL_TREE
1555           && type == TYPE_MAIN_VARIANT (TREE_TYPE (field)))
1556         {
1557           return field;
1558         }
1559
1560       /* Otherwise, it could be nested, search harder.  */
1561       if (DECL_NAME (field) == NULL_TREE
1562           && ANON_AGGR_TYPE_P (TREE_TYPE (field)))
1563         {
1564           tree subfield = lookup_anon_field (TREE_TYPE (field), type);
1565           if (subfield)
1566             return subfield;
1567         }
1568     }
1569   return NULL_TREE;
1570 }
1571
1572 /* Build an expression representing OBJECT.MEMBER.  OBJECT is an
1573    expression; MEMBER is a DECL or baselink.  If ACCESS_PATH is
1574    non-NULL, it indicates the path to the base used to name MEMBER.
1575    If PRESERVE_REFERENCE is true, the expression returned will have
1576    REFERENCE_TYPE if the MEMBER does.  Otherwise, the expression
1577    returned will have the type referred to by the reference.
1578
1579    This function does not perform access control; that is either done
1580    earlier by the parser when the name of MEMBER is resolved to MEMBER
1581    itself, or later when overload resolution selects one of the
1582    functions indicated by MEMBER.  */
1583
1584 tree
1585 build_class_member_access_expr (tree object, tree member,
1586                                 tree access_path, bool preserve_reference)
1587 {
1588   tree object_type;
1589   tree member_scope;
1590   tree result = NULL_TREE;
1591
1592   if (object == error_mark_node || member == error_mark_node)
1593     return error_mark_node;
1594
1595   if (TREE_CODE (member) == PSEUDO_DTOR_EXPR)
1596     return member;
1597
1598   my_friendly_assert (DECL_P (member) || BASELINK_P (member),
1599                       20020801);
1600
1601   /* [expr.ref]
1602
1603      The type of the first expression shall be "class object" (of a
1604      complete type).  */
1605   object_type = TREE_TYPE (object);
1606   if (!currently_open_class (object_type)
1607       && !complete_type_or_else (object_type, object))
1608     return error_mark_node;
1609   if (!CLASS_TYPE_P (object_type))
1610     {
1611       error ("request for member `%D' in `%E', which is of non-class type `%T'",
1612              member, object, object_type);
1613       return error_mark_node;
1614     }
1615
1616   /* The standard does not seem to actually say that MEMBER must be a
1617      member of OBJECT_TYPE.  However, that is clearly what is
1618      intended.  */
1619   if (DECL_P (member))
1620     {
1621       member_scope = DECL_CLASS_CONTEXT (member);
1622       mark_used (member);
1623       if (TREE_DEPRECATED (member))
1624         warn_deprecated_use (member);
1625     }
1626   else
1627     member_scope = BINFO_TYPE (BASELINK_BINFO (member));
1628   /* If MEMBER is from an anonymous aggregate, MEMBER_SCOPE will
1629      presently be the anonymous union.  Go outwards until we find a
1630      type related to OBJECT_TYPE.  */
1631   while (ANON_AGGR_TYPE_P (member_scope)
1632          && !same_type_ignoring_top_level_qualifiers_p (member_scope,
1633                                                         object_type))
1634     member_scope = TYPE_CONTEXT (member_scope);
1635   if (!member_scope || !DERIVED_FROM_P (member_scope, object_type))
1636     {
1637       if (TREE_CODE (member) == FIELD_DECL)
1638         error ("invalid use of nonstatic data member '%E'", member);
1639       else
1640         error ("`%D' is not a member of `%T'", member, object_type);
1641       return error_mark_node;
1642     }
1643
1644   /* Transform `(a, b).x' into `(*(a, &b)).x', `(a ? b : c).x' into
1645      `(*(a ?  &b : &c)).x', and so on.  A COND_EXPR is only an lvalue
1646      in the frontend; only _DECLs and _REFs are lvalues in the backend.  */
1647   {
1648     tree temp = unary_complex_lvalue (ADDR_EXPR, object);
1649     if (temp)
1650       object = build_indirect_ref (temp, NULL);
1651   }
1652
1653   /* In [expr.ref], there is an explicit list of the valid choices for
1654      MEMBER.  We check for each of those cases here.  */
1655   if (TREE_CODE (member) == VAR_DECL)
1656     {
1657       /* A static data member.  */
1658       result = member;
1659       /* If OBJECT has side-effects, they are supposed to occur.  */
1660       if (TREE_SIDE_EFFECTS (object))
1661         result = build (COMPOUND_EXPR, TREE_TYPE (result), object, result);
1662     }
1663   else if (TREE_CODE (member) == FIELD_DECL)
1664     {
1665       /* A non-static data member.  */
1666       bool null_object_p;
1667       int type_quals;
1668       tree member_type;
1669
1670       null_object_p = (TREE_CODE (object) == INDIRECT_REF
1671                        && integer_zerop (TREE_OPERAND (object, 0)));
1672
1673       /* Convert OBJECT to the type of MEMBER.  */
1674       if (!same_type_p (TYPE_MAIN_VARIANT (object_type),
1675                         TYPE_MAIN_VARIANT (member_scope)))
1676         {
1677           tree binfo;
1678           base_kind kind;
1679
1680           binfo = lookup_base (access_path ? access_path : object_type,
1681                                member_scope, ba_ignore,  &kind);
1682           if (binfo == error_mark_node)
1683             return error_mark_node;
1684
1685           /* It is invalid to try to get to a virtual base of a
1686              NULL object.  The most common cause is invalid use of
1687              offsetof macro.  */
1688           if (null_object_p && kind == bk_via_virtual)
1689             {
1690               error ("invalid access to non-static data member `%D' of NULL object",
1691                      member);
1692               error ("(perhaps the `offsetof' macro was used incorrectly)");
1693               return error_mark_node;
1694             }
1695
1696           /* Convert to the base.  */
1697           object = build_base_path (PLUS_EXPR, object, binfo,
1698                                     /*nonnull=*/1);
1699           /* If we found the base successfully then we should be able
1700              to convert to it successfully.  */
1701           my_friendly_assert (object != error_mark_node,
1702                               20020801);
1703         }
1704
1705       /* Complain about other invalid uses of offsetof, even though they will
1706          give the right answer.  Note that we complain whether or not they
1707          actually used the offsetof macro, since there's no way to know at this
1708          point.  So we just give a warning, instead of a pedwarn.  */
1709       if (null_object_p && warn_invalid_offsetof
1710           && CLASSTYPE_NON_POD_P (object_type)
1711           && ! skip_evaluation)
1712         {
1713           warning ("invalid access to non-static data member `%D' of NULL object",
1714                    member);
1715           warning  ("(perhaps the `offsetof' macro was used incorrectly)");
1716         }
1717
1718       /* If MEMBER is from an anonymous aggregate, we have converted
1719          OBJECT so that it refers to the class containing the
1720          anonymous union.  Generate a reference to the anonymous union
1721          itself, and recur to find MEMBER.  */
1722       if (ANON_AGGR_TYPE_P (DECL_CONTEXT (member))
1723           /* When this code is called from build_field_call, the
1724              object already has the type of the anonymous union.
1725              That is because the COMPONENT_REF was already
1726              constructed, and was then disassembled before calling
1727              build_field_call.  After the function-call code is
1728              cleaned up, this waste can be eliminated.  */
1729           && (!same_type_ignoring_top_level_qualifiers_p
1730               (TREE_TYPE (object), DECL_CONTEXT (member))))
1731         {
1732           tree anonymous_union;
1733
1734           anonymous_union = lookup_anon_field (TREE_TYPE (object),
1735                                                DECL_CONTEXT (member));
1736           object = build_class_member_access_expr (object,
1737                                                    anonymous_union,
1738                                                    /*access_path=*/NULL_TREE,
1739                                                    preserve_reference);
1740         }
1741
1742       /* Compute the type of the field, as described in [expr.ref].  */
1743       type_quals = TYPE_UNQUALIFIED;
1744       member_type = TREE_TYPE (member);
1745       if (TREE_CODE (member_type) != REFERENCE_TYPE)
1746         {
1747           type_quals = (cp_type_quals (member_type)
1748                         | cp_type_quals (object_type));
1749
1750           /* A field is const (volatile) if the enclosing object, or the
1751              field itself, is const (volatile).  But, a mutable field is
1752              not const, even within a const object.  */
1753           if (DECL_MUTABLE_P (member))
1754             type_quals &= ~TYPE_QUAL_CONST;
1755           member_type = cp_build_qualified_type (member_type, type_quals);
1756         }
1757
1758       result = fold (build (COMPONENT_REF, member_type, object, member,
1759                             NULL_TREE));
1760
1761       /* Mark the expression const or volatile, as appropriate.  Even
1762          though we've dealt with the type above, we still have to mark the
1763          expression itself.  */
1764       if (type_quals & TYPE_QUAL_CONST)
1765         TREE_READONLY (result) = 1;
1766       else if (type_quals & TYPE_QUAL_VOLATILE)
1767         TREE_THIS_VOLATILE (result) = 1;
1768     }
1769   else if (BASELINK_P (member))
1770     {
1771       /* The member is a (possibly overloaded) member function.  */
1772       tree functions;
1773       tree type;
1774
1775       /* If the MEMBER is exactly one static member function, then we
1776          know the type of the expression.  Otherwise, we must wait
1777          until overload resolution has been performed.  */
1778       functions = BASELINK_FUNCTIONS (member);
1779       if (TREE_CODE (functions) == FUNCTION_DECL
1780           && DECL_STATIC_FUNCTION_P (functions))
1781         type = TREE_TYPE (functions);
1782       else
1783         type = unknown_type_node;
1784       /* Note that we do not convert OBJECT to the BASELINK_BINFO
1785          base.  That will happen when the function is called.  */
1786       result = build (COMPONENT_REF, type, object, member, NULL_TREE);
1787     }
1788   else if (TREE_CODE (member) == CONST_DECL)
1789     {
1790       /* The member is an enumerator.  */
1791       result = member;
1792       /* If OBJECT has side-effects, they are supposed to occur.  */
1793       if (TREE_SIDE_EFFECTS (object))
1794         result = build (COMPOUND_EXPR, TREE_TYPE (result),
1795                         object, result);
1796     }
1797   else
1798     {
1799       error ("invalid use of `%D'", member);
1800       return error_mark_node;
1801     }
1802
1803   if (!preserve_reference)
1804     /* [expr.ref]
1805
1806        If E2 is declared to have type "reference to T", then ... the
1807        type of E1.E2 is T.  */
1808     result = convert_from_reference (result);
1809
1810   return result;
1811 }
1812
1813 /* Return the destructor denoted by OBJECT.SCOPE::~DTOR_NAME, or, if
1814    SCOPE is NULL, by OBJECT.~DTOR_NAME.  */
1815
1816 static tree
1817 lookup_destructor (tree object, tree scope, tree dtor_name)
1818 {
1819   tree object_type = TREE_TYPE (object);
1820   tree dtor_type = TREE_OPERAND (dtor_name, 0);
1821   tree expr;
1822
1823   if (scope && !check_dtor_name (scope, dtor_name))
1824     {
1825       error ("qualified type `%T' does not match destructor name `~%T'",
1826              scope, dtor_type);
1827       return error_mark_node;
1828     }
1829   if (!DERIVED_FROM_P (dtor_type, TYPE_MAIN_VARIANT (object_type)))
1830     {
1831       error ("the type being destroyed is `%T', but the destructor refers to `%T'",
1832              TYPE_MAIN_VARIANT (object_type), dtor_type);
1833       return error_mark_node;
1834     }
1835   if (!TYPE_HAS_DESTRUCTOR (dtor_type))
1836     return build (PSEUDO_DTOR_EXPR, void_type_node, object, scope,
1837                   dtor_type);
1838   expr = lookup_member (dtor_type, complete_dtor_identifier,
1839                         /*protect=*/1, /*want_type=*/false);
1840   expr = (adjust_result_of_qualified_name_lookup
1841           (expr, dtor_type, object_type));
1842   return expr;
1843 }
1844
1845 /* This function is called by the parser to process a class member
1846    access expression of the form OBJECT.NAME.  NAME is a node used by
1847    the parser to represent a name; it is not yet a DECL.  It may,
1848    however, be a BASELINK where the BASELINK_FUNCTIONS is a
1849    TEMPLATE_ID_EXPR.  Templates must be looked up by the parser, and
1850    there is no reason to do the lookup twice, so the parser keeps the
1851    BASELINK.  */
1852
1853 tree
1854 finish_class_member_access_expr (tree object, tree name)
1855 {
1856   tree expr;
1857   tree object_type;
1858   tree member;
1859   tree access_path = NULL_TREE;
1860   tree orig_object = object;
1861   tree orig_name = name;
1862
1863   if (object == error_mark_node || name == error_mark_node)
1864     return error_mark_node;
1865
1866   object_type = TREE_TYPE (object);
1867
1868   if (processing_template_decl)
1869     {
1870       if (/* If OBJECT_TYPE is dependent, so is OBJECT.NAME.  */
1871           dependent_type_p (object_type)
1872           /* If NAME is just an IDENTIFIER_NODE, then the expression
1873              is dependent.  */
1874           || TREE_CODE (object) == IDENTIFIER_NODE
1875           /* If NAME is "f<args>", where either 'f' or 'args' is
1876              dependent, then the expression is dependent.  */
1877           || (TREE_CODE (name) == TEMPLATE_ID_EXPR
1878               && dependent_template_id_p (TREE_OPERAND (name, 0),
1879                                           TREE_OPERAND (name, 1)))
1880           /* If NAME is "T::X" where "T" is dependent, then the
1881              expression is dependent.  */
1882           || (TREE_CODE (name) == SCOPE_REF
1883               && TYPE_P (TREE_OPERAND (name, 0))
1884               && dependent_type_p (TREE_OPERAND (name, 0))))
1885         return build_min_nt (COMPONENT_REF, object, name, NULL_TREE);
1886       object = build_non_dependent_expr (object);
1887     }
1888
1889   if (TREE_CODE (object_type) == REFERENCE_TYPE)
1890     {
1891       object = convert_from_reference (object);
1892       object_type = TREE_TYPE (object);
1893     }
1894
1895   /* [expr.ref]
1896
1897      The type of the first expression shall be "class object" (of a
1898      complete type).  */
1899   if (!currently_open_class (object_type)
1900       && !complete_type_or_else (object_type, object))
1901     return error_mark_node;
1902   if (!CLASS_TYPE_P (object_type))
1903     {
1904       error ("request for member `%D' in `%E', which is of non-class type `%T'",
1905              name, object, object_type);
1906       return error_mark_node;
1907     }
1908
1909   if (BASELINK_P (name))
1910     {
1911       /* A member function that has already been looked up.  */
1912       my_friendly_assert ((TREE_CODE (BASELINK_FUNCTIONS (name))
1913                            == TEMPLATE_ID_EXPR),
1914                           20020805);
1915       member = name;
1916     }
1917   else
1918     {
1919       bool is_template_id = false;
1920       tree template_args = NULL_TREE;
1921       tree scope;
1922
1923       if (TREE_CODE (name) == TEMPLATE_ID_EXPR)
1924         {
1925           is_template_id = true;
1926           template_args = TREE_OPERAND (name, 1);
1927           name = TREE_OPERAND (name, 0);
1928
1929           if (TREE_CODE (name) == OVERLOAD)
1930             name = DECL_NAME (get_first_fn (name));
1931           else if (DECL_P (name))
1932             name = DECL_NAME (name);
1933         }
1934
1935       if (TREE_CODE (name) == SCOPE_REF)
1936         {
1937           /* A qualified name.  The qualifying class or namespace `S' has
1938              already been looked up; it is either a TYPE or a
1939              NAMESPACE_DECL.  The member name is either an IDENTIFIER_NODE
1940              or a BIT_NOT_EXPR.  */
1941           scope = TREE_OPERAND (name, 0);
1942           name = TREE_OPERAND (name, 1);
1943           my_friendly_assert ((CLASS_TYPE_P (scope)
1944                                || TREE_CODE (scope) == NAMESPACE_DECL),
1945                               20020804);
1946           my_friendly_assert ((TREE_CODE (name) == IDENTIFIER_NODE
1947                                || TREE_CODE (name) == BIT_NOT_EXPR),
1948                               20020804);
1949
1950           /* If SCOPE is a namespace, then the qualified name does not
1951              name a member of OBJECT_TYPE.  */
1952           if (TREE_CODE (scope) == NAMESPACE_DECL)
1953             {
1954               error ("`%D::%D' is not a member of `%T'",
1955                      scope, name, object_type);
1956               return error_mark_node;
1957             }
1958
1959           /* Find the base of OBJECT_TYPE corresponding to SCOPE.  */
1960           access_path = lookup_base (object_type, scope, ba_check, NULL);
1961           if (access_path == error_mark_node)
1962             return error_mark_node;
1963           if (!access_path)
1964             {
1965               error ("`%T' is not a base of `%T'", scope, object_type);
1966               return error_mark_node;
1967             }
1968         }
1969       else
1970         {
1971           scope = NULL_TREE;
1972           access_path = object_type;
1973         }
1974
1975       if (TREE_CODE (name) == BIT_NOT_EXPR)
1976         member = lookup_destructor (object, scope, name);
1977       else
1978         {
1979           /* Look up the member.  */
1980           member = lookup_member (access_path, name, /*protect=*/1,
1981                                   /*want_type=*/false);
1982           if (member == NULL_TREE)
1983             {
1984               error ("'%D' has no member named '%E'", object_type, name);
1985               return error_mark_node;
1986             }
1987           if (member == error_mark_node)
1988             return error_mark_node;
1989         }
1990
1991       if (is_template_id)
1992         {
1993           tree template = member;
1994
1995           if (BASELINK_P (template))
1996             template = lookup_template_function (template, template_args);
1997           else
1998             {
1999               error ("`%D' is not a member template function", name);
2000               return error_mark_node;
2001             }
2002         }
2003     }
2004
2005   if (TREE_DEPRECATED (member))
2006     warn_deprecated_use (member);
2007
2008   expr = build_class_member_access_expr (object, member, access_path,
2009                                          /*preserve_reference=*/false);
2010   if (processing_template_decl && expr != error_mark_node)
2011     return build_min_non_dep (COMPONENT_REF, expr,
2012                               orig_object, orig_name, NULL_TREE);
2013   return expr;
2014 }
2015
2016 /* Return an expression for the MEMBER_NAME field in the internal
2017    representation of PTRMEM, a pointer-to-member function.  (Each
2018    pointer-to-member function type gets its own RECORD_TYPE so it is
2019    more convenient to access the fields by name than by FIELD_DECL.)
2020    This routine converts the NAME to a FIELD_DECL and then creates the
2021    node for the complete expression.  */
2022
2023 tree
2024 build_ptrmemfunc_access_expr (tree ptrmem, tree member_name)
2025 {
2026   tree ptrmem_type;
2027   tree member;
2028   tree member_type;
2029
2030   /* This code is a stripped down version of
2031      build_class_member_access_expr.  It does not work to use that
2032      routine directly because it expects the object to be of class
2033      type.  */
2034   ptrmem_type = TREE_TYPE (ptrmem);
2035   my_friendly_assert (TYPE_PTRMEMFUNC_P (ptrmem_type), 20020804);
2036   member = lookup_member (ptrmem_type, member_name, /*protect=*/0,
2037                           /*want_type=*/false);
2038   member_type = cp_build_qualified_type (TREE_TYPE (member),
2039                                          cp_type_quals (ptrmem_type));
2040   return fold (build (COMPONENT_REF, member_type, ptrmem, member, NULL_TREE));
2041 }
2042
2043 /* Given an expression PTR for a pointer, return an expression
2044    for the value pointed to.
2045    ERRORSTRING is the name of the operator to appear in error messages.
2046
2047    This function may need to overload OPERATOR_FNNAME.
2048    Must also handle REFERENCE_TYPEs for C++.  */
2049
2050 tree
2051 build_x_indirect_ref (tree expr, const char *errorstring)
2052 {
2053   tree orig_expr = expr;
2054   tree rval;
2055
2056   if (processing_template_decl)
2057     {
2058       if (type_dependent_expression_p (expr))
2059         return build_min_nt (INDIRECT_REF, expr);
2060       expr = build_non_dependent_expr (expr);
2061     }
2062
2063   rval = build_new_op (INDIRECT_REF, LOOKUP_NORMAL, expr, NULL_TREE,
2064                        NULL_TREE, /*overloaded_p=*/NULL);
2065   if (!rval)
2066     rval = build_indirect_ref (expr, errorstring);
2067
2068   if (processing_template_decl && rval != error_mark_node)
2069     return build_min_non_dep (INDIRECT_REF, rval, orig_expr);
2070   else
2071     return rval;
2072 }
2073
2074 tree
2075 build_indirect_ref (tree ptr, const char *errorstring)
2076 {
2077   tree pointer, type;
2078
2079   if (ptr == error_mark_node)
2080     return error_mark_node;
2081
2082   if (ptr == current_class_ptr)
2083     return current_class_ref;
2084
2085   pointer = (TREE_CODE (TREE_TYPE (ptr)) == REFERENCE_TYPE
2086              ? ptr : decay_conversion (ptr));
2087   type = TREE_TYPE (pointer);
2088
2089   if (TYPE_PTR_P (type) || TREE_CODE (type) == REFERENCE_TYPE)
2090     {
2091       /* [expr.unary.op]
2092
2093          If the type of the expression is "pointer to T," the type
2094          of  the  result  is  "T."
2095
2096          We must use the canonical variant because certain parts of
2097          the back end, like fold, do pointer comparisons between
2098          types.  */
2099       tree t = canonical_type_variant (TREE_TYPE (type));
2100
2101       if (VOID_TYPE_P (t))
2102         {
2103           /* A pointer to incomplete type (other than cv void) can be
2104              dereferenced [expr.unary.op]/1  */
2105           error ("`%T' is not a pointer-to-object type", type);
2106           return error_mark_node;
2107         }
2108       else if (TREE_CODE (pointer) == ADDR_EXPR
2109                && same_type_p (t, TREE_TYPE (TREE_OPERAND (pointer, 0))))
2110         /* The POINTER was something like `&x'.  We simplify `*&x' to
2111            `x'.  */
2112         return TREE_OPERAND (pointer, 0);
2113       else
2114         {
2115           tree ref = build1 (INDIRECT_REF, t, pointer);
2116
2117           /* We *must* set TREE_READONLY when dereferencing a pointer to const,
2118              so that we get the proper error message if the result is used
2119              to assign to.  Also, &* is supposed to be a no-op.  */
2120           TREE_READONLY (ref) = CP_TYPE_CONST_P (t);
2121           TREE_THIS_VOLATILE (ref) = CP_TYPE_VOLATILE_P (t);
2122           TREE_SIDE_EFFECTS (ref)
2123             = (TREE_THIS_VOLATILE (ref) || TREE_SIDE_EFFECTS (pointer));
2124           return ref;
2125         }
2126     }
2127   /* `pointer' won't be an error_mark_node if we were given a
2128      pointer to member, so it's cool to check for this here.  */
2129   else if (TYPE_PTR_TO_MEMBER_P (type))
2130     error ("invalid use of `%s' on pointer to member", errorstring);
2131   else if (pointer != error_mark_node)
2132     {
2133       if (errorstring)
2134         error ("invalid type argument of `%s'", errorstring);
2135       else
2136         error ("invalid type argument");
2137     }
2138   return error_mark_node;
2139 }
2140
2141 /* This handles expressions of the form "a[i]", which denotes
2142    an array reference.
2143
2144    This is logically equivalent in C to *(a+i), but we may do it differently.
2145    If A is a variable or a member, we generate a primitive ARRAY_REF.
2146    This avoids forcing the array out of registers, and can work on
2147    arrays that are not lvalues (for example, members of structures returned
2148    by functions).
2149
2150    If INDEX is of some user-defined type, it must be converted to
2151    integer type.  Otherwise, to make a compatible PLUS_EXPR, it
2152    will inherit the type of the array, which will be some pointer type.  */
2153
2154 tree
2155 build_array_ref (tree array, tree idx)
2156 {
2157   if (idx == 0)
2158     {
2159       error ("subscript missing in array reference");
2160       return error_mark_node;
2161     }
2162
2163   if (TREE_TYPE (array) == error_mark_node
2164       || TREE_TYPE (idx) == error_mark_node)
2165     return error_mark_node;
2166
2167   /* If ARRAY is a COMPOUND_EXPR or COND_EXPR, move our reference
2168      inside it.  */
2169   switch (TREE_CODE (array))
2170     {
2171     case COMPOUND_EXPR:
2172       {
2173         tree value = build_array_ref (TREE_OPERAND (array, 1), idx);
2174         return build (COMPOUND_EXPR, TREE_TYPE (value),
2175                       TREE_OPERAND (array, 0), value);
2176       }
2177
2178     case COND_EXPR:
2179       return build_conditional_expr
2180         (TREE_OPERAND (array, 0),
2181          build_array_ref (TREE_OPERAND (array, 1), idx),
2182          build_array_ref (TREE_OPERAND (array, 2), idx));
2183
2184     default:
2185       break;
2186     }
2187
2188   if (TREE_CODE (TREE_TYPE (array)) == ARRAY_TYPE)
2189     {
2190       tree rval, type;
2191
2192       /* Subscripting with type char is likely to lose
2193          on a machine where chars are signed.
2194          So warn on any machine, but optionally.
2195          Don't warn for unsigned char since that type is safe.
2196          Don't warn for signed char because anyone who uses that
2197          must have done so deliberately.  */
2198       if (warn_char_subscripts
2199           && TYPE_MAIN_VARIANT (TREE_TYPE (idx)) == char_type_node)
2200         warning ("array subscript has type `char'");
2201
2202       if (!INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (idx)))
2203         {
2204           error ("array subscript is not an integer");
2205           return error_mark_node;
2206         }
2207
2208       /* Apply integral promotions *after* noticing character types.
2209          (It is unclear why we do these promotions -- the standard
2210          does not say that we should.  In fact, the natual thing would
2211          seem to be to convert IDX to ptrdiff_t; we're performing
2212          pointer arithmetic.)  */
2213       idx = perform_integral_promotions (idx);
2214
2215       /* An array that is indexed by a non-constant
2216          cannot be stored in a register; we must be able to do
2217          address arithmetic on its address.
2218          Likewise an array of elements of variable size.  */
2219       if (TREE_CODE (idx) != INTEGER_CST
2220           || (COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (array)))
2221               && (TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (array))))
2222                   != INTEGER_CST)))
2223         {
2224           if (!cxx_mark_addressable (array))
2225             return error_mark_node;
2226         }
2227
2228       /* An array that is indexed by a constant value which is not within
2229          the array bounds cannot be stored in a register either; because we
2230          would get a crash in store_bit_field/extract_bit_field when trying
2231          to access a non-existent part of the register.  */
2232       if (TREE_CODE (idx) == INTEGER_CST
2233           && TYPE_DOMAIN (TREE_TYPE (array))
2234           && ! int_fits_type_p (idx, TYPE_DOMAIN (TREE_TYPE (array))))
2235         {
2236           if (!cxx_mark_addressable (array))
2237             return error_mark_node;
2238         }
2239
2240       if (pedantic && !lvalue_p (array))
2241         pedwarn ("ISO C++ forbids subscripting non-lvalue array");
2242
2243       /* Note in C++ it is valid to subscript a `register' array, since
2244          it is valid to take the address of something with that
2245          storage specification.  */
2246       if (extra_warnings)
2247         {
2248           tree foo = array;
2249           while (TREE_CODE (foo) == COMPONENT_REF)
2250             foo = TREE_OPERAND (foo, 0);
2251           if (TREE_CODE (foo) == VAR_DECL && DECL_REGISTER (foo))
2252             warning ("subscripting array declared `register'");
2253         }
2254
2255       type = TREE_TYPE (TREE_TYPE (array));
2256       rval = build (ARRAY_REF, type, array, idx, NULL_TREE, NULL_TREE);
2257       /* Array ref is const/volatile if the array elements are
2258          or if the array is..  */
2259       TREE_READONLY (rval)
2260         |= (CP_TYPE_CONST_P (type) | TREE_READONLY (array));
2261       TREE_SIDE_EFFECTS (rval)
2262         |= (CP_TYPE_VOLATILE_P (type) | TREE_SIDE_EFFECTS (array));
2263       TREE_THIS_VOLATILE (rval)
2264         |= (CP_TYPE_VOLATILE_P (type) | TREE_THIS_VOLATILE (array));
2265       return require_complete_type (fold (rval));
2266     }
2267
2268   {
2269     tree ar = default_conversion (array);
2270     tree ind = default_conversion (idx);
2271
2272     /* Put the integer in IND to simplify error checking.  */
2273     if (TREE_CODE (TREE_TYPE (ar)) == INTEGER_TYPE)
2274       {
2275         tree temp = ar;
2276         ar = ind;
2277         ind = temp;
2278       }
2279
2280     if (ar == error_mark_node)
2281       return ar;
2282
2283     if (TREE_CODE (TREE_TYPE (ar)) != POINTER_TYPE)
2284       {
2285         error ("subscripted value is neither array nor pointer");
2286         return error_mark_node;
2287       }
2288     if (TREE_CODE (TREE_TYPE (ind)) != INTEGER_TYPE)
2289       {
2290         error ("array subscript is not an integer");
2291         return error_mark_node;
2292       }
2293
2294     return build_indirect_ref (cp_build_binary_op (PLUS_EXPR, ar, ind),
2295                                "array indexing");
2296   }
2297 }
2298 \f
2299 /* Resolve a pointer to member function.  INSTANCE is the object
2300    instance to use, if the member points to a virtual member.
2301
2302    This used to avoid checking for virtual functions if basetype
2303    has no virtual functions, according to an earlier ANSI draft.
2304    With the final ISO C++ rules, such an optimization is
2305    incorrect: A pointer to a derived member can be static_cast
2306    to pointer-to-base-member, as long as the dynamic object
2307    later has the right member.  */
2308
2309 tree
2310 get_member_function_from_ptrfunc (tree *instance_ptrptr, tree function)
2311 {
2312   if (TREE_CODE (function) == OFFSET_REF)
2313     function = TREE_OPERAND (function, 1);
2314
2315   if (TYPE_PTRMEMFUNC_P (TREE_TYPE (function)))
2316     {
2317       tree idx, delta, e1, e2, e3, vtbl, basetype;
2318       tree fntype = TYPE_PTRMEMFUNC_FN_TYPE (TREE_TYPE (function));
2319
2320       tree instance_ptr = *instance_ptrptr;
2321       tree instance_save_expr = 0;
2322       if (instance_ptr == error_mark_node)
2323         {
2324           if (TREE_CODE (function) == PTRMEM_CST)
2325             {
2326               /* Extracting the function address from a pmf is only
2327                  allowed with -Wno-pmf-conversions. It only works for
2328                  pmf constants.  */
2329               e1 = build_addr_func (PTRMEM_CST_MEMBER (function));
2330               e1 = convert (fntype, e1);
2331               return e1;
2332             }
2333           else
2334             {
2335               error ("object missing in use of `%E'", function);
2336               return error_mark_node;
2337             }
2338         }
2339
2340       if (TREE_SIDE_EFFECTS (instance_ptr))
2341         instance_ptr = instance_save_expr = save_expr (instance_ptr);
2342
2343       if (TREE_SIDE_EFFECTS (function))
2344         function = save_expr (function);
2345
2346       /* Start by extracting all the information from the PMF itself.  */
2347       e3 = PFN_FROM_PTRMEMFUNC (function);
2348       delta = build_ptrmemfunc_access_expr (function, delta_identifier);
2349       idx = build1 (NOP_EXPR, vtable_index_type, e3);
2350       switch (TARGET_PTRMEMFUNC_VBIT_LOCATION)
2351         {
2352         case ptrmemfunc_vbit_in_pfn:
2353           e1 = cp_build_binary_op (BIT_AND_EXPR, idx, integer_one_node);
2354           idx = cp_build_binary_op (MINUS_EXPR, idx, integer_one_node);
2355           break;
2356
2357         case ptrmemfunc_vbit_in_delta:
2358           e1 = cp_build_binary_op (BIT_AND_EXPR, delta, integer_one_node);
2359           delta = cp_build_binary_op (RSHIFT_EXPR, delta, integer_one_node);
2360           break;
2361
2362         default:
2363           abort ();
2364         }
2365
2366       /* Convert down to the right base before using the instance.  First
2367          use the type...  */
2368       basetype = TYPE_METHOD_BASETYPE (TREE_TYPE (fntype));
2369       basetype = lookup_base (TREE_TYPE (TREE_TYPE (instance_ptr)),
2370                               basetype, ba_check, NULL);
2371       instance_ptr = build_base_path (PLUS_EXPR, instance_ptr, basetype, 1);
2372       if (instance_ptr == error_mark_node)
2373         return error_mark_node;
2374       /* ...and then the delta in the PMF.  */
2375       instance_ptr = build (PLUS_EXPR, TREE_TYPE (instance_ptr),
2376                             instance_ptr, delta);
2377
2378       /* Hand back the adjusted 'this' argument to our caller.  */
2379       *instance_ptrptr = instance_ptr;
2380
2381       /* Next extract the vtable pointer from the object.  */
2382       vtbl = build1 (NOP_EXPR, build_pointer_type (vtbl_ptr_type_node),
2383                      instance_ptr);
2384       vtbl = build_indirect_ref (vtbl, NULL);
2385
2386       /* Finally, extract the function pointer from the vtable.  */
2387       e2 = fold (build (PLUS_EXPR, TREE_TYPE (vtbl), vtbl, idx));
2388       e2 = build_indirect_ref (e2, NULL);
2389       TREE_CONSTANT (e2) = 1;
2390       TREE_INVARIANT (e2) = 1;
2391
2392       /* When using function descriptors, the address of the
2393          vtable entry is treated as a function pointer.  */
2394       if (TARGET_VTABLE_USES_DESCRIPTORS)
2395         e2 = build1 (NOP_EXPR, TREE_TYPE (e2),
2396                      build_unary_op (ADDR_EXPR, e2, /*noconvert=*/1));
2397
2398       TREE_TYPE (e2) = TREE_TYPE (e3);
2399       e1 = build_conditional_expr (e1, e2, e3);
2400
2401       /* Make sure this doesn't get evaluated first inside one of the
2402          branches of the COND_EXPR.  */
2403       if (instance_save_expr)
2404         e1 = build (COMPOUND_EXPR, TREE_TYPE (e1),
2405                     instance_save_expr, e1);
2406
2407       function = e1;
2408     }
2409   return function;
2410 }
2411
2412 tree
2413 build_function_call (tree function, tree params)
2414 {
2415   tree fntype, fndecl;
2416   tree coerced_params;
2417   tree name = NULL_TREE;
2418   int is_method;
2419   tree original = function;
2420
2421   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
2422      Strip such NOP_EXPRs, since FUNCTION is used in non-lvalue context.  */
2423   if (TREE_CODE (function) == NOP_EXPR
2424       && TREE_TYPE (function) == TREE_TYPE (TREE_OPERAND (function, 0)))
2425     function = TREE_OPERAND (function, 0);
2426
2427   if (TREE_CODE (function) == FUNCTION_DECL)
2428     {
2429       name = DECL_NAME (function);
2430
2431       mark_used (function);
2432       fndecl = function;
2433
2434       /* Convert anything with function type to a pointer-to-function.  */
2435       if (pedantic && DECL_MAIN_P (function))
2436         pedwarn ("ISO C++ forbids calling `::main' from within program");
2437
2438       /* Differs from default_conversion by not setting TREE_ADDRESSABLE
2439          (because calling an inline function does not mean the function
2440          needs to be separately compiled).  */
2441
2442       if (DECL_INLINE (function))
2443         function = inline_conversion (function);
2444       else
2445         function = build_addr_func (function);
2446     }
2447   else
2448     {
2449       fndecl = NULL_TREE;
2450
2451       function = build_addr_func (function);
2452     }
2453
2454   if (function == error_mark_node)
2455     return error_mark_node;
2456
2457   fntype = TREE_TYPE (function);
2458
2459   if (TYPE_PTRMEMFUNC_P (fntype))
2460     {
2461       error ("must use .* or ->* to call pointer-to-member function in `%E (...)'",
2462                 original);
2463       return error_mark_node;
2464     }
2465
2466   is_method = (TREE_CODE (fntype) == POINTER_TYPE
2467                && TREE_CODE (TREE_TYPE (fntype)) == METHOD_TYPE);
2468
2469   if (!((TREE_CODE (fntype) == POINTER_TYPE
2470          && TREE_CODE (TREE_TYPE (fntype)) == FUNCTION_TYPE)
2471         || is_method
2472         || TREE_CODE (function) == TEMPLATE_ID_EXPR))
2473     {
2474       error ("`%E' cannot be used as a function", original);
2475       return error_mark_node;
2476     }
2477
2478   /* fntype now gets the type of function pointed to.  */
2479   fntype = TREE_TYPE (fntype);
2480
2481   /* Convert the parameters to the types declared in the
2482      function prototype, or apply default promotions.  */
2483
2484   coerced_params = convert_arguments (TYPE_ARG_TYPES (fntype),
2485                                       params, fndecl, LOOKUP_NORMAL);
2486   if (coerced_params == error_mark_node)
2487     return error_mark_node;
2488
2489   /* Check for errors in format strings and inappropriately
2490      null parameters.  */
2491
2492   check_function_arguments (TYPE_ATTRIBUTES (fntype), coerced_params);
2493
2494   return build_cxx_call (function, coerced_params);
2495 }
2496 \f
2497 /* Convert the actual parameter expressions in the list VALUES
2498    to the types in the list TYPELIST.
2499    If parmdecls is exhausted, or when an element has NULL as its type,
2500    perform the default conversions.
2501
2502    NAME is an IDENTIFIER_NODE or 0.  It is used only for error messages.
2503
2504    This is also where warnings about wrong number of args are generated.
2505
2506    Return a list of expressions for the parameters as converted.
2507
2508    Both VALUES and the returned value are chains of TREE_LIST nodes
2509    with the elements of the list in the TREE_VALUE slots of those nodes.
2510
2511    In C++, unspecified trailing parameters can be filled in with their
2512    default arguments, if such were specified.  Do so here.  */
2513
2514 tree
2515 convert_arguments (tree typelist, tree values, tree fndecl, int flags)
2516 {
2517   tree typetail, valtail;
2518   tree result = NULL_TREE;
2519   const char *called_thing = 0;
2520   int i = 0;
2521
2522   /* Argument passing is always copy-initialization.  */
2523   flags |= LOOKUP_ONLYCONVERTING;
2524
2525   if (fndecl)
2526     {
2527       if (TREE_CODE (TREE_TYPE (fndecl)) == METHOD_TYPE)
2528         {
2529           if (DECL_NAME (fndecl) == NULL_TREE
2530               || IDENTIFIER_HAS_TYPE_VALUE (DECL_NAME (fndecl)))
2531             called_thing = "constructor";
2532           else
2533             called_thing = "member function";
2534         }
2535       else
2536         called_thing = "function";
2537     }
2538
2539   for (valtail = values, typetail = typelist;
2540        valtail;
2541        valtail = TREE_CHAIN (valtail), i++)
2542     {
2543       tree type = typetail ? TREE_VALUE (typetail) : 0;
2544       tree val = TREE_VALUE (valtail);
2545
2546       if (val == error_mark_node)
2547         return error_mark_node;
2548
2549       if (type == void_type_node)
2550         {
2551           if (fndecl)
2552             {
2553               cp_error_at ("too many arguments to %s `%+#D'", called_thing,
2554                            fndecl);
2555               error ("at this point in file");
2556             }
2557           else
2558             error ("too many arguments to function");
2559           /* In case anybody wants to know if this argument
2560              list is valid.  */
2561           if (result)
2562             TREE_TYPE (tree_last (result)) = error_mark_node;
2563           break;
2564         }
2565
2566       /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
2567          Strip such NOP_EXPRs, since VAL is used in non-lvalue context.  */
2568       if (TREE_CODE (val) == NOP_EXPR
2569           && TREE_TYPE (val) == TREE_TYPE (TREE_OPERAND (val, 0))
2570           && (type == 0 || TREE_CODE (type) != REFERENCE_TYPE))
2571         val = TREE_OPERAND (val, 0);
2572
2573       if (type == 0 || TREE_CODE (type) != REFERENCE_TYPE)
2574         {
2575           if (TREE_CODE (TREE_TYPE (val)) == ARRAY_TYPE
2576               || TREE_CODE (TREE_TYPE (val)) == FUNCTION_TYPE
2577               || TREE_CODE (TREE_TYPE (val)) == METHOD_TYPE)
2578             val = decay_conversion (val);
2579         }
2580
2581       if (val == error_mark_node)
2582         return error_mark_node;
2583
2584       if (type != 0)
2585         {
2586           /* Formal parm type is specified by a function prototype.  */
2587           tree parmval;
2588
2589           if (!COMPLETE_TYPE_P (complete_type (type)))
2590             {
2591               if (fndecl)
2592                 error ("parameter %P of `%D' has incomplete type `%T'",
2593                        i, fndecl, type);
2594               else
2595                 error ("parameter %P has incomplete type `%T'", i, type);
2596               parmval = error_mark_node;
2597             }
2598           else
2599             {
2600               parmval = convert_for_initialization
2601                 (NULL_TREE, type, val, flags,
2602                  "argument passing", fndecl, i);
2603               parmval = convert_for_arg_passing (type, parmval);
2604             }
2605
2606           if (parmval == error_mark_node)
2607             return error_mark_node;
2608
2609           result = tree_cons (NULL_TREE, parmval, result);
2610         }
2611       else
2612         {
2613           if (TREE_CODE (TREE_TYPE (val)) == REFERENCE_TYPE)
2614             val = convert_from_reference (val);
2615
2616           if (fndecl && DECL_BUILT_IN (fndecl)
2617               && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_CONSTANT_P)
2618             /* Don't do ellipsis conversion for __built_in_constant_p
2619                as this will result in spurious warnings for non-POD
2620                types.  */
2621             val = require_complete_type (val);
2622           else
2623             val = convert_arg_to_ellipsis (val);
2624
2625           result = tree_cons (NULL_TREE, val, result);
2626         }
2627
2628       if (typetail)
2629         typetail = TREE_CHAIN (typetail);
2630     }
2631
2632   if (typetail != 0 && typetail != void_list_node)
2633     {
2634       /* See if there are default arguments that can be used.  */
2635       if (TREE_PURPOSE (typetail)
2636           && TREE_CODE (TREE_PURPOSE (typetail)) != DEFAULT_ARG)
2637         {
2638           for (; typetail != void_list_node; ++i)
2639             {
2640               tree parmval
2641                 = convert_default_arg (TREE_VALUE (typetail),
2642                                        TREE_PURPOSE (typetail),
2643                                        fndecl, i);
2644
2645               if (parmval == error_mark_node)
2646                 return error_mark_node;
2647
2648               result = tree_cons (0, parmval, result);
2649               typetail = TREE_CHAIN (typetail);
2650               /* ends with `...'.  */
2651               if (typetail == NULL_TREE)
2652                 break;
2653             }
2654         }
2655       else
2656         {
2657           if (fndecl)
2658             {
2659               cp_error_at ("too few arguments to %s `%+#D'",
2660                            called_thing, fndecl);
2661               error ("at this point in file");
2662             }
2663           else
2664             error ("too few arguments to function");
2665           return error_mark_list;
2666         }
2667     }
2668
2669   return nreverse (result);
2670 }
2671 \f
2672 /* Build a binary-operation expression, after performing default
2673    conversions on the operands.  CODE is the kind of expression to build.  */
2674
2675 tree
2676 build_x_binary_op (enum tree_code code, tree arg1, tree arg2,
2677                    bool *overloaded_p)
2678 {
2679   tree orig_arg1;
2680   tree orig_arg2;
2681   tree expr;
2682
2683   orig_arg1 = arg1;
2684   orig_arg2 = arg2;
2685
2686   if (processing_template_decl)
2687     {
2688       if (type_dependent_expression_p (arg1)
2689           || type_dependent_expression_p (arg2))
2690         return build_min_nt (code, arg1, arg2);
2691       arg1 = build_non_dependent_expr (arg1);
2692       arg2 = build_non_dependent_expr (arg2);
2693     }
2694
2695   if (code == DOTSTAR_EXPR)
2696     expr = build_m_component_ref (arg1, arg2);
2697   else
2698     expr = build_new_op (code, LOOKUP_NORMAL, arg1, arg2, NULL_TREE,
2699                          overloaded_p);
2700
2701   if (processing_template_decl && expr != error_mark_node)
2702     return build_min_non_dep (code, expr, orig_arg1, orig_arg2);
2703
2704   return expr;
2705 }
2706
2707 /* Build a binary-operation expression without default conversions.
2708    CODE is the kind of expression to build.
2709    This function differs from `build' in several ways:
2710    the data type of the result is computed and recorded in it,
2711    warnings are generated if arg data types are invalid,
2712    special handling for addition and subtraction of pointers is known,
2713    and some optimization is done (operations on narrow ints
2714    are done in the narrower type when that gives the same result).
2715    Constant folding is also done before the result is returned.
2716
2717    Note that the operands will never have enumeral types
2718    because either they have just had the default conversions performed
2719    or they have both just been converted to some other type in which
2720    the arithmetic is to be done.
2721
2722    C++: must do special pointer arithmetic when implementing
2723    multiple inheritance, and deal with pointer to member functions.  */
2724
2725 tree
2726 build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
2727                  int convert_p ATTRIBUTE_UNUSED)
2728 {
2729   tree op0, op1;
2730   enum tree_code code0, code1;
2731   tree type0, type1;
2732
2733   /* Expression code to give to the expression when it is built.
2734      Normally this is CODE, which is what the caller asked for,
2735      but in some special cases we change it.  */
2736   enum tree_code resultcode = code;
2737
2738   /* Data type in which the computation is to be performed.
2739      In the simplest cases this is the common type of the arguments.  */
2740   tree result_type = NULL;
2741
2742   /* Nonzero means operands have already been type-converted
2743      in whatever way is necessary.
2744      Zero means they need to be converted to RESULT_TYPE.  */
2745   int converted = 0;
2746
2747   /* Nonzero means create the expression with this type, rather than
2748      RESULT_TYPE.  */
2749   tree build_type = 0;
2750
2751   /* Nonzero means after finally constructing the expression
2752      convert it to this type.  */
2753   tree final_type = 0;
2754
2755   /* Nonzero if this is an operation like MIN or MAX which can
2756      safely be computed in short if both args are promoted shorts.
2757      Also implies COMMON.
2758      -1 indicates a bitwise operation; this makes a difference
2759      in the exact conditions for when it is safe to do the operation
2760      in a narrower mode.  */
2761   int shorten = 0;
2762
2763   /* Nonzero if this is a comparison operation;
2764      if both args are promoted shorts, compare the original shorts.
2765      Also implies COMMON.  */
2766   int short_compare = 0;
2767
2768   /* Nonzero if this is a right-shift operation, which can be computed on the
2769      original short and then promoted if the operand is a promoted short.  */
2770   int short_shift = 0;
2771
2772   /* Nonzero means set RESULT_TYPE to the common type of the args.  */
2773   int common = 0;
2774
2775   /* Apply default conversions.  */
2776   op0 = orig_op0;
2777   op1 = orig_op1;
2778
2779   if (code == TRUTH_AND_EXPR || code == TRUTH_ANDIF_EXPR
2780       || code == TRUTH_OR_EXPR || code == TRUTH_ORIF_EXPR
2781       || code == TRUTH_XOR_EXPR)
2782     {
2783       if (!really_overloaded_fn (op0))
2784         op0 = decay_conversion (op0);
2785       if (!really_overloaded_fn (op1))
2786         op1 = decay_conversion (op1);
2787     }
2788   else
2789     {
2790       if (!really_overloaded_fn (op0))
2791         op0 = default_conversion (op0);
2792       if (!really_overloaded_fn (op1))
2793         op1 = default_conversion (op1);
2794     }
2795
2796   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
2797   STRIP_TYPE_NOPS (op0);
2798   STRIP_TYPE_NOPS (op1);
2799
2800   /* DTRT if one side is an overloaded function, but complain about it.  */
2801   if (type_unknown_p (op0))
2802     {
2803       tree t = instantiate_type (TREE_TYPE (op1), op0, tf_none);
2804       if (t != error_mark_node)
2805         {
2806           pedwarn ("assuming cast to type `%T' from overloaded function",
2807                       TREE_TYPE (t));
2808           op0 = t;
2809         }
2810     }
2811   if (type_unknown_p (op1))
2812     {
2813       tree t = instantiate_type (TREE_TYPE (op0), op1, tf_none);
2814       if (t != error_mark_node)
2815         {
2816           pedwarn ("assuming cast to type `%T' from overloaded function",
2817                       TREE_TYPE (t));
2818           op1 = t;
2819         }
2820     }
2821
2822   type0 = TREE_TYPE (op0);
2823   type1 = TREE_TYPE (op1);
2824
2825   /* The expression codes of the data types of the arguments tell us
2826      whether the arguments are integers, floating, pointers, etc.  */
2827   code0 = TREE_CODE (type0);
2828   code1 = TREE_CODE (type1);
2829
2830   /* If an error was already reported for one of the arguments,
2831      avoid reporting another error.  */
2832
2833   if (code0 == ERROR_MARK || code1 == ERROR_MARK)
2834     return error_mark_node;
2835
2836   switch (code)
2837     {
2838     case PLUS_EXPR:
2839       /* Handle the pointer + int case.  */
2840       if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
2841         return cp_pointer_int_sum (PLUS_EXPR, op0, op1);
2842       else if (code1 == POINTER_TYPE && code0 == INTEGER_TYPE)
2843         return cp_pointer_int_sum (PLUS_EXPR, op1, op0);
2844       else
2845         common = 1;
2846       break;
2847
2848     case MINUS_EXPR:
2849       /* Subtraction of two similar pointers.
2850          We must subtract them as integers, then divide by object size.  */
2851       if (code0 == POINTER_TYPE && code1 == POINTER_TYPE
2852           && same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (type0),
2853                                                         TREE_TYPE (type1)))
2854         return pointer_diff (op0, op1, common_type (type0, type1));
2855       /* Handle pointer minus int.  Just like pointer plus int.  */
2856       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
2857         return cp_pointer_int_sum (MINUS_EXPR, op0, op1);
2858       else
2859         common = 1;
2860       break;
2861
2862     case MULT_EXPR:
2863       common = 1;
2864       break;
2865
2866     case TRUNC_DIV_EXPR:
2867     case CEIL_DIV_EXPR:
2868     case FLOOR_DIV_EXPR:
2869     case ROUND_DIV_EXPR:
2870     case EXACT_DIV_EXPR:
2871       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
2872            || code0 == COMPLEX_TYPE)
2873           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
2874               || code1 == COMPLEX_TYPE))
2875         {
2876           if (TREE_CODE (op1) == INTEGER_CST && integer_zerop (op1))
2877             warning ("division by zero in `%E / 0'", op0);
2878           else if (TREE_CODE (op1) == REAL_CST && real_zerop (op1))
2879             warning ("division by zero in `%E / 0.'", op0);
2880
2881           if (!(code0 == INTEGER_TYPE && code1 == INTEGER_TYPE))
2882             resultcode = RDIV_EXPR;
2883           else
2884             /* When dividing two signed integers, we have to promote to int.
2885                unless we divide by a constant != -1.  Note that default
2886                conversion will have been performed on the operands at this
2887                point, so we have to dig out the original type to find out if
2888                it was unsigned.  */
2889             shorten = ((TREE_CODE (op0) == NOP_EXPR
2890                         && TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op0, 0))))
2891                        || (TREE_CODE (op1) == INTEGER_CST
2892                            && ! integer_all_onesp (op1)));
2893
2894           common = 1;
2895         }
2896       break;
2897
2898     case BIT_AND_EXPR:
2899     case BIT_IOR_EXPR:
2900     case BIT_XOR_EXPR:
2901       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2902         shorten = -1;
2903       break;
2904
2905     case TRUNC_MOD_EXPR:
2906     case FLOOR_MOD_EXPR:
2907       if (code1 == INTEGER_TYPE && integer_zerop (op1))
2908         warning ("division by zero in `%E %% 0'", op0);
2909       else if (code1 == REAL_TYPE && real_zerop (op1))
2910         warning ("division by zero in `%E %% 0.'", op0);
2911
2912       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2913         {
2914           /* Although it would be tempting to shorten always here, that loses
2915              on some targets, since the modulo instruction is undefined if the
2916              quotient can't be represented in the computation mode.  We shorten
2917              only if unsigned or if dividing by something we know != -1.  */
2918           shorten = ((TREE_CODE (op0) == NOP_EXPR
2919                       && TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op0, 0))))
2920                      || (TREE_CODE (op1) == INTEGER_CST
2921                          && ! integer_all_onesp (op1)));
2922           common = 1;
2923         }
2924       break;
2925
2926     case TRUTH_ANDIF_EXPR:
2927     case TRUTH_ORIF_EXPR:
2928     case TRUTH_AND_EXPR:
2929     case TRUTH_OR_EXPR:
2930       result_type = boolean_type_node;
2931       break;
2932
2933       /* Shift operations: result has same type as first operand;
2934          always convert second operand to int.
2935          Also set SHORT_SHIFT if shifting rightward.  */
2936
2937     case RSHIFT_EXPR:
2938       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2939         {
2940           result_type = type0;
2941           if (TREE_CODE (op1) == INTEGER_CST)
2942             {
2943               if (tree_int_cst_lt (op1, integer_zero_node))
2944                 warning ("right shift count is negative");
2945               else
2946                 {
2947                   if (! integer_zerop (op1))
2948                     short_shift = 1;
2949                   if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
2950                     warning ("right shift count >= width of type");
2951                 }
2952             }
2953           /* Convert the shift-count to an integer, regardless of
2954              size of value being shifted.  */
2955           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
2956             op1 = cp_convert (integer_type_node, op1);
2957           /* Avoid converting op1 to result_type later.  */
2958           converted = 1;
2959         }
2960       break;
2961
2962     case LSHIFT_EXPR:
2963       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2964         {
2965           result_type = type0;
2966           if (TREE_CODE (op1) == INTEGER_CST)
2967             {
2968               if (tree_int_cst_lt (op1, integer_zero_node))
2969                 warning ("left shift count is negative");
2970               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
2971                 warning ("left shift count >= width of type");
2972             }
2973           /* Convert the shift-count to an integer, regardless of
2974              size of value being shifted.  */
2975           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
2976             op1 = cp_convert (integer_type_node, op1);
2977           /* Avoid converting op1 to result_type later.  */
2978           converted = 1;
2979         }
2980       break;
2981
2982     case RROTATE_EXPR:
2983     case LROTATE_EXPR:
2984       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2985         {
2986           result_type = type0;
2987           if (TREE_CODE (op1) == INTEGER_CST)
2988             {
2989               if (tree_int_cst_lt (op1, integer_zero_node))
2990                 warning ("%s rotate count is negative",
2991                          (code == LROTATE_EXPR) ? "left" : "right");
2992               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
2993                 warning ("%s rotate count >= width of type",
2994                          (code == LROTATE_EXPR) ? "left" : "right");
2995             }
2996           /* Convert the shift-count to an integer, regardless of
2997              size of value being shifted.  */
2998           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
2999             op1 = cp_convert (integer_type_node, op1);
3000         }
3001       break;
3002
3003     case EQ_EXPR:
3004     case NE_EXPR:
3005       if (warn_float_equal && (code0 == REAL_TYPE || code1 == REAL_TYPE))
3006         warning ("comparing floating point with == or != is unsafe");
3007
3008       build_type = boolean_type_node;
3009       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
3010            || code0 == COMPLEX_TYPE)
3011           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
3012               || code1 == COMPLEX_TYPE))
3013         short_compare = 1;
3014       else if ((code0 == POINTER_TYPE && code1 == POINTER_TYPE)
3015                || (TYPE_PTRMEM_P (type0) && TYPE_PTRMEM_P (type1)))
3016         result_type = composite_pointer_type (type0, type1, op0, op1,
3017                                               "comparison");
3018       else if ((code0 == POINTER_TYPE || TYPE_PTRMEM_P (type0))
3019                && null_ptr_cst_p (op1))
3020         result_type = type0;
3021       else if ((code1 == POINTER_TYPE || TYPE_PTRMEM_P (type1))
3022                && null_ptr_cst_p (op0))
3023         result_type = type1;
3024       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
3025         {
3026           result_type = type0;
3027           error ("ISO C++ forbids comparison between pointer and integer");
3028         }
3029       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
3030         {
3031           result_type = type1;
3032           error ("ISO C++ forbids comparison between pointer and integer");
3033         }
3034       else if (TYPE_PTRMEMFUNC_P (type0) && null_ptr_cst_p (op1))
3035         {
3036           op0 = build_ptrmemfunc_access_expr (op0, pfn_identifier);
3037           op1 = cp_convert (TREE_TYPE (op0), integer_zero_node);
3038           result_type = TREE_TYPE (op0);
3039         }
3040       else if (TYPE_PTRMEMFUNC_P (type1) && null_ptr_cst_p (op0))
3041         return cp_build_binary_op (code, op1, op0);
3042       else if (TYPE_PTRMEMFUNC_P (type0) && TYPE_PTRMEMFUNC_P (type1)
3043                && same_type_p (type0, type1))
3044         {
3045           /* E will be the final comparison.  */
3046           tree e;
3047           /* E1 and E2 are for scratch.  */
3048           tree e1;
3049           tree e2;
3050           tree pfn0;
3051           tree pfn1;
3052           tree delta0;
3053           tree delta1;
3054
3055           if (TREE_SIDE_EFFECTS (op0))
3056             op0 = save_expr (op0);
3057           if (TREE_SIDE_EFFECTS (op1))
3058             op1 = save_expr (op1);
3059
3060           /* We generate:
3061
3062              (op0.pfn == op1.pfn
3063               && (!op0.pfn || op0.delta == op1.delta))
3064
3065              The reason for the `!op0.pfn' bit is that a NULL
3066              pointer-to-member is any member with a zero PFN; the
3067              DELTA field is unspecified.  */
3068           pfn0 = pfn_from_ptrmemfunc (op0);
3069           pfn1 = pfn_from_ptrmemfunc (op1);
3070           delta0 = build_ptrmemfunc_access_expr (op0,
3071                                                  delta_identifier);
3072           delta1 = build_ptrmemfunc_access_expr (op1,
3073                                                  delta_identifier);
3074           e1 = cp_build_binary_op (EQ_EXPR, delta0, delta1);
3075           e2 = cp_build_binary_op (EQ_EXPR,
3076                                    pfn0,
3077                                    cp_convert (TREE_TYPE (pfn0),
3078                                                integer_zero_node));
3079           e1 = cp_build_binary_op (TRUTH_ORIF_EXPR, e1, e2);
3080           e2 = build (EQ_EXPR, boolean_type_node, pfn0, pfn1);
3081           e = cp_build_binary_op (TRUTH_ANDIF_EXPR, e2, e1);
3082           if (code == EQ_EXPR)
3083             return e;
3084           return cp_build_binary_op (EQ_EXPR, e, integer_zero_node);
3085         }
3086       else if ((TYPE_PTRMEMFUNC_P (type0)
3087                 && same_type_p (TYPE_PTRMEMFUNC_FN_TYPE (type0), type1))
3088                || (TYPE_PTRMEMFUNC_P (type1)
3089                    && same_type_p (TYPE_PTRMEMFUNC_FN_TYPE (type1), type0)))
3090         abort ();
3091       break;
3092
3093     case MAX_EXPR:
3094     case MIN_EXPR:
3095       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
3096            && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
3097         shorten = 1;
3098       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
3099         result_type = composite_pointer_type (type0, type1, op0, op1,
3100                                               "comparison");
3101       break;
3102
3103     case LE_EXPR:
3104     case GE_EXPR:
3105     case LT_EXPR:
3106     case GT_EXPR:
3107       build_type = boolean_type_node;
3108       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
3109            && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
3110         short_compare = 1;
3111       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
3112         result_type = composite_pointer_type (type0, type1, op0, op1,
3113                                               "comparison");
3114       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
3115                && integer_zerop (op1))
3116         result_type = type0;
3117       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
3118                && integer_zerop (op0))
3119         result_type = type1;
3120       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
3121         {
3122           result_type = type0;
3123           pedwarn ("ISO C++ forbids comparison between pointer and integer");
3124         }
3125       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
3126         {
3127           result_type = type1;
3128           pedwarn ("ISO C++ forbids comparison between pointer and integer");
3129         }
3130       break;
3131
3132     case UNORDERED_EXPR:
3133     case ORDERED_EXPR:
3134     case UNLT_EXPR:
3135     case UNLE_EXPR:
3136     case UNGT_EXPR:
3137     case UNGE_EXPR:
3138     case UNEQ_EXPR:
3139       build_type = integer_type_node;
3140       if (code0 != REAL_TYPE || code1 != REAL_TYPE)
3141         {
3142           error ("unordered comparison on non-floating point argument");
3143           return error_mark_node;
3144         }
3145       common = 1;
3146       break;
3147
3148     default:
3149       break;
3150     }
3151
3152   if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE || code0 == COMPLEX_TYPE)
3153       &&
3154       (code1 == INTEGER_TYPE || code1 == REAL_TYPE || code1 == COMPLEX_TYPE))
3155     {
3156       int none_complex = (code0 != COMPLEX_TYPE && code1 != COMPLEX_TYPE);
3157
3158       if (shorten || common || short_compare)
3159         result_type = common_type (type0, type1);
3160
3161       /* For certain operations (which identify themselves by shorten != 0)
3162          if both args were extended from the same smaller type,
3163          do the arithmetic in that type and then extend.
3164
3165          shorten !=0 and !=1 indicates a bitwise operation.
3166          For them, this optimization is safe only if
3167          both args are zero-extended or both are sign-extended.
3168          Otherwise, we might change the result.
3169          Eg, (short)-1 | (unsigned short)-1 is (int)-1
3170          but calculated in (unsigned short) it would be (unsigned short)-1.  */
3171
3172       if (shorten && none_complex)
3173         {
3174           int unsigned0, unsigned1;
3175           tree arg0 = get_narrower (op0, &unsigned0);
3176           tree arg1 = get_narrower (op1, &unsigned1);
3177           /* UNS is 1 if the operation to be done is an unsigned one.  */
3178           int uns = TYPE_UNSIGNED (result_type);
3179           tree type;
3180
3181           final_type = result_type;
3182
3183           /* Handle the case that OP0 does not *contain* a conversion
3184              but it *requires* conversion to FINAL_TYPE.  */
3185
3186           if (op0 == arg0 && TREE_TYPE (op0) != final_type)
3187             unsigned0 = TYPE_UNSIGNED (TREE_TYPE (op0));
3188           if (op1 == arg1 && TREE_TYPE (op1) != final_type)
3189             unsigned1 = TYPE_UNSIGNED (TREE_TYPE (op1));
3190
3191           /* Now UNSIGNED0 is 1 if ARG0 zero-extends to FINAL_TYPE.  */
3192
3193           /* For bitwise operations, signedness of nominal type
3194              does not matter.  Consider only how operands were extended.  */
3195           if (shorten == -1)
3196             uns = unsigned0;
3197
3198           /* Note that in all three cases below we refrain from optimizing
3199              an unsigned operation on sign-extended args.
3200              That would not be valid.  */
3201
3202           /* Both args variable: if both extended in same way
3203              from same width, do it in that width.
3204              Do it unsigned if args were zero-extended.  */
3205           if ((TYPE_PRECISION (TREE_TYPE (arg0))
3206                < TYPE_PRECISION (result_type))
3207               && (TYPE_PRECISION (TREE_TYPE (arg1))
3208                   == TYPE_PRECISION (TREE_TYPE (arg0)))
3209               && unsigned0 == unsigned1
3210               && (unsigned0 || !uns))
3211             result_type = c_common_signed_or_unsigned_type
3212               (unsigned0, common_type (TREE_TYPE (arg0), TREE_TYPE (arg1)));
3213           else if (TREE_CODE (arg0) == INTEGER_CST
3214                    && (unsigned1 || !uns)
3215                    && (TYPE_PRECISION (TREE_TYPE (arg1))
3216                        < TYPE_PRECISION (result_type))
3217                    && (type = c_common_signed_or_unsigned_type
3218                        (unsigned1, TREE_TYPE (arg1)),
3219                        int_fits_type_p (arg0, type)))
3220             result_type = type;
3221           else if (TREE_CODE (arg1) == INTEGER_CST
3222                    && (unsigned0 || !uns)
3223                    && (TYPE_PRECISION (TREE_TYPE (arg0))
3224                        < TYPE_PRECISION (result_type))
3225                    && (type = c_common_signed_or_unsigned_type
3226                        (unsigned0, TREE_TYPE (arg0)),
3227                        int_fits_type_p (arg1, type)))
3228             result_type = type;
3229         }
3230
3231       /* Shifts can be shortened if shifting right.  */
3232
3233       if (short_shift)
3234         {
3235           int unsigned_arg;
3236           tree arg0 = get_narrower (op0, &unsigned_arg);
3237
3238           final_type = result_type;
3239
3240           if (arg0 == op0 && final_type == TREE_TYPE (op0))
3241             unsigned_arg = TYPE_UNSIGNED (TREE_TYPE (op0));
3242
3243           if (TYPE_PRECISION (TREE_TYPE (arg0)) < TYPE_PRECISION (result_type)
3244               /* We can shorten only if the shift count is less than the
3245                  number of bits in the smaller type size.  */
3246               && compare_tree_int (op1, TYPE_PRECISION (TREE_TYPE (arg0))) < 0
3247               /* If arg is sign-extended and then unsigned-shifted,
3248                  we can simulate this with a signed shift in arg's type
3249                  only if the extended result is at least twice as wide
3250                  as the arg.  Otherwise, the shift could use up all the
3251                  ones made by sign-extension and bring in zeros.
3252                  We can't optimize that case at all, but in most machines
3253                  it never happens because available widths are 2**N.  */
3254               && (!TYPE_UNSIGNED (final_type)
3255                   || unsigned_arg
3256                   || (((unsigned) 2 * TYPE_PRECISION (TREE_TYPE (arg0)))
3257                       <= TYPE_PRECISION (result_type))))
3258             {
3259               /* Do an unsigned shift if the operand was zero-extended.  */
3260               result_type
3261                 = c_common_signed_or_unsigned_type (unsigned_arg,
3262                                                     TREE_TYPE (arg0));
3263               /* Convert value-to-be-shifted to that type.  */
3264               if (TREE_TYPE (op0) != result_type)
3265                 op0 = cp_convert (result_type, op0);
3266               converted = 1;
3267             }
3268         }
3269
3270       /* Comparison operations are shortened too but differently.
3271          They identify themselves by setting short_compare = 1.  */
3272
3273       if (short_compare)
3274         {
3275           /* Don't write &op0, etc., because that would prevent op0
3276              from being kept in a register.
3277              Instead, make copies of the our local variables and
3278              pass the copies by reference, then copy them back afterward.  */
3279           tree xop0 = op0, xop1 = op1, xresult_type = result_type;
3280           enum tree_code xresultcode = resultcode;
3281           tree val
3282             = shorten_compare (&xop0, &xop1, &xresult_type, &xresultcode);
3283           if (val != 0)
3284             return cp_convert (boolean_type_node, val);
3285           op0 = xop0, op1 = xop1;
3286           converted = 1;
3287           resultcode = xresultcode;
3288         }
3289
3290       if ((short_compare || code == MIN_EXPR || code == MAX_EXPR)
3291           && warn_sign_compare
3292           /* Do not warn until the template is instantiated; we cannot
3293              bound the ranges of the arguments until that point.  */
3294           && !processing_template_decl)
3295         {
3296           int op0_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op0));
3297           int op1_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op1));
3298
3299           int unsignedp0, unsignedp1;
3300           tree primop0 = get_narrower (op0, &unsignedp0);
3301           tree primop1 = get_narrower (op1, &unsignedp1);
3302
3303           /* Check for comparison of different enum types.  */
3304           if (TREE_CODE (TREE_TYPE (orig_op0)) == ENUMERAL_TYPE
3305               && TREE_CODE (TREE_TYPE (orig_op1)) == ENUMERAL_TYPE
3306               && TYPE_MAIN_VARIANT (TREE_TYPE (orig_op0))
3307                  != TYPE_MAIN_VARIANT (TREE_TYPE (orig_op1)))
3308             {
3309               warning ("comparison between types `%#T' and `%#T'",
3310                           TREE_TYPE (orig_op0), TREE_TYPE (orig_op1));
3311             }
3312
3313           /* Give warnings for comparisons between signed and unsigned
3314              quantities that may fail.  */
3315           /* Do the checking based on the original operand trees, so that
3316              casts will be considered, but default promotions won't be.  */
3317
3318           /* Do not warn if the comparison is being done in a signed type,
3319              since the signed type will only be chosen if it can represent
3320              all the values of the unsigned type.  */
3321           if (!TYPE_UNSIGNED (result_type))
3322             /* OK */;
3323           /* Do not warn if both operands are unsigned.  */
3324           else if (op0_signed == op1_signed)
3325             /* OK */;
3326           /* Do not warn if the signed quantity is an unsuffixed
3327              integer literal (or some static constant expression
3328              involving such literals or a conditional expression
3329              involving such literals) and it is non-negative.  */
3330           else if ((op0_signed && tree_expr_nonnegative_p (orig_op0))
3331                    || (op1_signed && tree_expr_nonnegative_p (orig_op1)))
3332             /* OK */;
3333           /* Do not warn if the comparison is an equality operation,
3334              the unsigned quantity is an integral constant and it does
3335              not use the most significant bit of result_type.  */
3336           else if ((resultcode == EQ_EXPR || resultcode == NE_EXPR)
3337                    && ((op0_signed && TREE_CODE (orig_op1) == INTEGER_CST
3338                         && int_fits_type_p (orig_op1, c_common_signed_type
3339                                             (result_type)))
3340                         || (op1_signed && TREE_CODE (orig_op0) == INTEGER_CST
3341                             && int_fits_type_p (orig_op0, c_common_signed_type
3342                                                 (result_type)))))
3343             /* OK */;
3344           else
3345             warning ("comparison between signed and unsigned integer expressions");
3346
3347           /* Warn if two unsigned values are being compared in a size
3348              larger than their original size, and one (and only one) is the
3349              result of a `~' operator.  This comparison will always fail.
3350
3351              Also warn if one operand is a constant, and the constant does not
3352              have all bits set that are set in the ~ operand when it is
3353              extended.  */
3354
3355           if ((TREE_CODE (primop0) == BIT_NOT_EXPR)
3356               ^ (TREE_CODE (primop1) == BIT_NOT_EXPR))
3357             {
3358               if (TREE_CODE (primop0) == BIT_NOT_EXPR)
3359                 primop0 = get_narrower (TREE_OPERAND (op0, 0), &unsignedp0);
3360               if (TREE_CODE (primop1) == BIT_NOT_EXPR)
3361                 primop1 = get_narrower (TREE_OPERAND (op1, 0), &unsignedp1);
3362
3363               if (host_integerp (primop0, 0) || host_integerp (primop1, 0))
3364                 {
3365                   tree primop;
3366                   HOST_WIDE_INT constant, mask;
3367                   int unsignedp;
3368                   unsigned int bits;
3369
3370                   if (host_integerp (primop0, 0))
3371                     {
3372                       primop = primop1;
3373                       unsignedp = unsignedp1;
3374                       constant = tree_low_cst (primop0, 0);
3375                     }
3376                   else
3377                     {
3378                       primop = primop0;
3379                       unsignedp = unsignedp0;
3380                       constant = tree_low_cst (primop1, 0);
3381                     }
3382
3383                   bits = TYPE_PRECISION (TREE_TYPE (primop));
3384                   if (bits < TYPE_PRECISION (result_type)
3385                       && bits < HOST_BITS_PER_LONG && unsignedp)
3386                     {
3387                       mask = (~ (HOST_WIDE_INT) 0) << bits;
3388                       if ((mask & constant) != mask)
3389                         warning ("comparison of promoted ~unsigned with constant");
3390                     }
3391                 }
3392               else if (unsignedp0 && unsignedp1
3393                        && (TYPE_PRECISION (TREE_TYPE (primop0))
3394                            < TYPE_PRECISION (result_type))
3395                        && (TYPE_PRECISION (TREE_TYPE (primop1))
3396                            < TYPE_PRECISION (result_type)))
3397                 warning ("comparison of promoted ~unsigned with unsigned");
3398             }
3399         }
3400     }
3401
3402   /* At this point, RESULT_TYPE must be nonzero to avoid an error message.
3403      If CONVERTED is zero, both args will be converted to type RESULT_TYPE.
3404      Then the expression will be built.
3405      It will be given type FINAL_TYPE if that is nonzero;
3406      otherwise, it will be given type RESULT_TYPE.  */
3407
3408   if (!result_type)
3409     {
3410       error ("invalid operands of types `%T' and `%T' to binary `%O'",
3411                 TREE_TYPE (orig_op0), TREE_TYPE (orig_op1), code);
3412       return error_mark_node;
3413     }
3414
3415   /* Issue warnings about peculiar, but valid, uses of NULL.  */
3416   if (/* It's reasonable to use pointer values as operands of &&
3417          and ||, so NULL is no exception.  */
3418       !(code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
3419       && (/* If OP0 is NULL and OP1 is not a pointer, or vice versa.  */
3420           (orig_op0 == null_node
3421            && TREE_CODE (TREE_TYPE (op1)) != POINTER_TYPE)
3422           /* Or vice versa.  */
3423           || (orig_op1 == null_node
3424               && TREE_CODE (TREE_TYPE (op0)) != POINTER_TYPE)
3425           /* Or, both are NULL and the operation was not a comparison.  */
3426           || (orig_op0 == null_node && orig_op1 == null_node
3427               && code != EQ_EXPR && code != NE_EXPR)))
3428     /* Some sort of arithmetic operation involving NULL was
3429        performed.  Note that pointer-difference and pointer-addition
3430        have already been handled above, and so we don't end up here in
3431        that case.  */
3432     warning ("NULL used in arithmetic");
3433
3434   if (! converted)
3435     {
3436       if (TREE_TYPE (op0) != result_type)
3437         op0 = cp_convert (result_type, op0);
3438       if (TREE_TYPE (op1) != result_type)
3439         op1 = cp_convert (result_type, op1);
3440
3441       if (op0 == error_mark_node || op1 == error_mark_node)
3442         return error_mark_node;
3443     }
3444
3445   if (build_type == NULL_TREE)
3446     build_type = result_type;
3447
3448   {
3449     tree result = fold (build (resultcode, build_type, op0, op1));
3450     if (final_type != 0)
3451       result = cp_convert (final_type, result);
3452     return result;
3453   }
3454 }
3455 \f
3456 /* Return a tree for the sum or difference (RESULTCODE says which)
3457    of pointer PTROP and integer INTOP.  */
3458
3459 static tree
3460 cp_pointer_int_sum (enum tree_code resultcode, tree ptrop, tree intop)
3461 {
3462   tree res_type = TREE_TYPE (ptrop);
3463
3464   /* pointer_int_sum() uses size_in_bytes() on the TREE_TYPE(res_type)
3465      in certain circumstance (when it's valid to do so).  So we need
3466      to make sure it's complete.  We don't need to check here, if we
3467      can actually complete it at all, as those checks will be done in
3468      pointer_int_sum() anyway.  */
3469   complete_type (TREE_TYPE (res_type));
3470
3471   return pointer_int_sum (resultcode, ptrop, fold (intop));
3472 }
3473
3474 /* Return a tree for the difference of pointers OP0 and OP1.
3475    The resulting tree has type int.  */
3476
3477 static tree
3478 pointer_diff (tree op0, tree op1, tree ptrtype)
3479 {
3480   tree result;
3481   tree restype = ptrdiff_type_node;
3482   tree target_type = TREE_TYPE (ptrtype);
3483
3484   if (!complete_type_or_else (target_type, NULL_TREE))
3485     return error_mark_node;
3486
3487   if (pedantic || warn_pointer_arith)
3488     {
3489       if (TREE_CODE (target_type) == VOID_TYPE)
3490         pedwarn ("ISO C++ forbids using pointer of type `void *' in subtraction");
3491       if (TREE_CODE (target_type) == FUNCTION_TYPE)
3492         pedwarn ("ISO C++ forbids using pointer to a function in subtraction");
3493       if (TREE_CODE (target_type) == METHOD_TYPE)
3494         pedwarn ("ISO C++ forbids using pointer to a method in subtraction");
3495     }
3496
3497   /* First do the subtraction as integers;
3498      then drop through to build the divide operator.  */
3499
3500   op0 = cp_build_binary_op (MINUS_EXPR,
3501                             cp_convert (restype, op0),
3502                             cp_convert (restype, op1));
3503
3504   /* This generates an error if op1 is a pointer to an incomplete type.  */
3505   if (!COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (op1))))
3506     error ("invalid use of a pointer to an incomplete type in pointer arithmetic");
3507
3508   op1 = (TYPE_PTROB_P (ptrtype)
3509          ? size_in_bytes (target_type)
3510          : integer_one_node);
3511
3512   /* Do the division.  */
3513
3514   result = build (EXACT_DIV_EXPR, restype, op0, cp_convert (restype, op1));
3515   return fold (result);
3516 }
3517 \f
3518 /* Construct and perhaps optimize a tree representation
3519    for a unary operation.  CODE, a tree_code, specifies the operation
3520    and XARG is the operand.  */
3521
3522 tree
3523 build_x_unary_op (enum tree_code code, tree xarg)
3524 {
3525   tree orig_expr = xarg;
3526   tree exp;
3527   int ptrmem = 0;
3528
3529   if (processing_template_decl)
3530     {
3531       if (type_dependent_expression_p (xarg))
3532         return build_min_nt (code, xarg, NULL_TREE);
3533
3534       /* For non-dependent pointer-to-member, the SCOPE_REF will be
3535          processed during template substitution.  Just compute the
3536          right type here and build an ADDR_EXPR around it for
3537          diagnostics.  */
3538       if (code == ADDR_EXPR && TREE_CODE (xarg) == SCOPE_REF)
3539         {
3540           tree type;
3541           if (TREE_TYPE (xarg) == unknown_type_node)
3542             type = unknown_type_node;
3543           else if (TREE_CODE (TREE_TYPE (xarg)) == FUNCTION_TYPE)
3544             type = build_pointer_type (TREE_TYPE (xarg));
3545           else
3546             type = build_ptrmem_type (TREE_OPERAND (xarg, 0),
3547                                       TREE_TYPE (xarg));
3548           return build_min (code, type, xarg, NULL_TREE);
3549         }
3550
3551       xarg = build_non_dependent_expr (xarg);
3552     }
3553
3554   exp = NULL_TREE;
3555
3556   /* [expr.unary.op] says:
3557
3558        The address of an object of incomplete type can be taken.
3559
3560      (And is just the ordinary address operator, not an overloaded
3561      "operator &".)  However, if the type is a template
3562      specialization, we must complete the type at this point so that
3563      an overloaded "operator &" will be available if required.  */
3564   if (code == ADDR_EXPR
3565       && TREE_CODE (xarg) != TEMPLATE_ID_EXPR
3566       && ((CLASS_TYPE_P (TREE_TYPE (xarg))
3567            && !COMPLETE_TYPE_P (complete_type (TREE_TYPE (xarg))))
3568           || (TREE_CODE (xarg) == OFFSET_REF)))
3569     /* Don't look for a function.  */;
3570   else
3571     exp = build_new_op (code, LOOKUP_NORMAL, xarg, NULL_TREE, NULL_TREE,
3572                         /*overloaded_p=*/NULL);
3573   if (!exp && code == ADDR_EXPR)
3574     {
3575       /*  A pointer to member-function can be formed only by saying
3576           &X::mf.  */
3577       if (!flag_ms_extensions && TREE_CODE (TREE_TYPE (xarg)) == METHOD_TYPE
3578           && (TREE_CODE (xarg) != OFFSET_REF || !PTRMEM_OK_P (xarg)))
3579         {
3580           if (TREE_CODE (xarg) != OFFSET_REF)
3581             {
3582               error ("invalid use of '%E' to form a pointer-to-member-function.  Use a qualified-id.",
3583                      xarg);
3584               return error_mark_node;
3585             }
3586           else
3587             {
3588               error ("parenthesis around '%E' cannot be used to form a pointer-to-member-function",
3589                      xarg);
3590               PTRMEM_OK_P (xarg) = 1;
3591             }
3592         }
3593
3594       if (TREE_CODE (xarg) == OFFSET_REF)
3595         {
3596           ptrmem = PTRMEM_OK_P (xarg);
3597
3598           if (!ptrmem && !flag_ms_extensions
3599               && TREE_CODE (TREE_TYPE (TREE_OPERAND (xarg, 1))) == METHOD_TYPE)
3600             {
3601               /* A single non-static member, make sure we don't allow a
3602                  pointer-to-member.  */
3603               xarg = build (OFFSET_REF, TREE_TYPE (xarg),
3604                             TREE_OPERAND (xarg, 0),
3605                             ovl_cons (TREE_OPERAND (xarg, 1), NULL_TREE));
3606               PTRMEM_OK_P (xarg) = ptrmem;
3607             }
3608         }
3609       else if (TREE_CODE (xarg) == TARGET_EXPR)
3610         warning ("taking address of temporary");
3611       exp = build_unary_op (ADDR_EXPR, xarg, 0);
3612       if (TREE_CODE (exp) == ADDR_EXPR)
3613         PTRMEM_OK_P (exp) = ptrmem;
3614     }
3615
3616   if (processing_template_decl && exp != error_mark_node)
3617     return build_min_non_dep (code, exp, orig_expr,
3618                               /*For {PRE,POST}{INC,DEC}REMENT_EXPR*/NULL_TREE);
3619   return exp;
3620 }
3621
3622 /* Like c_common_truthvalue_conversion, but handle pointer-to-member
3623    constants, where a null value is represented by an INTEGER_CST of
3624    -1.  */
3625
3626 tree
3627 cp_truthvalue_conversion (tree expr)
3628 {
3629   tree type = TREE_TYPE (expr);
3630   if (TYPE_PTRMEM_P (type))
3631     return build_binary_op (NE_EXPR, expr, integer_zero_node, 1);
3632   else
3633     return c_common_truthvalue_conversion (expr);
3634 }
3635
3636 /* Just like cp_truthvalue_conversion, but we want a CLEANUP_POINT_EXPR.  */
3637
3638 tree
3639 condition_conversion (tree expr)
3640 {
3641   tree t;
3642   if (processing_template_decl)
3643     return expr;
3644   t = perform_implicit_conversion (boolean_type_node, expr);
3645   t = fold (build1 (CLEANUP_POINT_EXPR, boolean_type_node, t));
3646   return t;
3647 }
3648
3649 /* Return an ADDR_EXPR giving the address of T.  This function
3650    attempts no optimizations or simplifications; it is a low-level
3651    primitive.  */
3652
3653 tree
3654 build_address (tree t)
3655 {
3656   tree addr;
3657
3658   if (error_operand_p (t) || !cxx_mark_addressable (t))
3659     return error_mark_node;
3660
3661   addr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (t)), t);
3662
3663   return addr;
3664 }
3665
3666 /* Return a NOP_EXPR converting EXPR to TYPE.  */
3667
3668 tree
3669 build_nop (tree type, tree expr)
3670 {
3671   if (type == error_mark_node || error_operand_p (expr))
3672     return expr;
3673   return build1 (NOP_EXPR, type, expr);
3674 }
3675
3676 /* C++: Must handle pointers to members.
3677
3678    Perhaps type instantiation should be extended to handle conversion
3679    from aggregates to types we don't yet know we want?  (Or are those
3680    cases typically errors which should be reported?)
3681
3682    NOCONVERT nonzero suppresses the default promotions
3683    (such as from short to int).  */
3684
3685 tree
3686 build_unary_op (enum tree_code code, tree xarg, int noconvert)
3687 {
3688   /* No default_conversion here.  It causes trouble for ADDR_EXPR.  */
3689   tree arg = xarg;
3690   tree argtype = 0;
3691   const char *errstring = NULL;
3692   tree val;
3693
3694   if (arg == error_mark_node)
3695     return error_mark_node;
3696
3697   switch (code)
3698     {
3699     case CONVERT_EXPR:
3700       /* This is used for unary plus, because a CONVERT_EXPR
3701          is enough to prevent anybody from looking inside for
3702          associativity, but won't generate any code.  */
3703       if (!(arg = build_expr_type_conversion
3704             (WANT_ARITH | WANT_ENUM | WANT_POINTER, arg, true)))
3705         errstring = "wrong type argument to unary plus";
3706       else
3707         {
3708           if (!noconvert)
3709             arg = default_conversion (arg);
3710           arg = build1 (NON_LVALUE_EXPR, TREE_TYPE (arg), arg);
3711         }
3712       break;
3713
3714     case NEGATE_EXPR:
3715       if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_ENUM, arg, true)))
3716         errstring = "wrong type argument to unary minus";
3717       else if (!noconvert && CP_INTEGRAL_TYPE_P (TREE_TYPE (arg)))
3718         arg = perform_integral_promotions (arg);
3719       break;
3720
3721     case BIT_NOT_EXPR:
3722       if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
3723         {
3724           code = CONJ_EXPR;
3725           if (!noconvert)
3726             arg = default_conversion (arg);
3727         }
3728       else if (!(arg = build_expr_type_conversion (WANT_INT | WANT_ENUM,
3729                                                    arg, true)))
3730         errstring = "wrong type argument to bit-complement";
3731       else if (!noconvert)
3732         arg = perform_integral_promotions (arg);
3733       break;
3734
3735     case ABS_EXPR:
3736       if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_ENUM, arg, true)))
3737         errstring = "wrong type argument to abs";
3738       else if (!noconvert)
3739         arg = default_conversion (arg);
3740       break;
3741
3742     case CONJ_EXPR:
3743       /* Conjugating a real value is a no-op, but allow it anyway.  */
3744       if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_ENUM, arg, true)))
3745         errstring = "wrong type argument to conjugation";
3746       else if (!noconvert)
3747         arg = default_conversion (arg);
3748       break;
3749
3750     case TRUTH_NOT_EXPR:
3751       arg = perform_implicit_conversion (boolean_type_node, arg);
3752       val = invert_truthvalue (arg);
3753       if (arg != error_mark_node)
3754         return val;
3755       errstring = "in argument to unary !";
3756       break;
3757
3758     case NOP_EXPR:
3759       break;
3760
3761     case REALPART_EXPR:
3762       if (TREE_CODE (arg) == COMPLEX_CST)
3763         return TREE_REALPART (arg);
3764       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
3765         return fold (build1 (REALPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg));
3766       else
3767         return arg;
3768
3769     case IMAGPART_EXPR:
3770       if (TREE_CODE (arg) == COMPLEX_CST)
3771         return TREE_IMAGPART (arg);
3772       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
3773         return fold (build1 (IMAGPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg));
3774       else
3775         return cp_convert (TREE_TYPE (arg), integer_zero_node);
3776
3777     case PREINCREMENT_EXPR:
3778     case POSTINCREMENT_EXPR:
3779     case PREDECREMENT_EXPR:
3780     case POSTDECREMENT_EXPR:
3781       /* Handle complex lvalues (when permitted)
3782          by reduction to simpler cases.  */
3783
3784       val = unary_complex_lvalue (code, arg);
3785       if (val != 0)
3786         return val;
3787
3788       /* Increment or decrement the real part of the value,
3789          and don't change the imaginary part.  */
3790       if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
3791         {
3792           tree real, imag;
3793
3794           arg = stabilize_reference (arg);
3795           real = build_unary_op (REALPART_EXPR, arg, 1);
3796           imag = build_unary_op (IMAGPART_EXPR, arg, 1);
3797           return build (COMPLEX_EXPR, TREE_TYPE (arg),
3798                         build_unary_op (code, real, 1), imag);
3799         }
3800
3801       /* Report invalid types.  */
3802
3803       if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_POINTER,
3804                                               arg, true)))
3805         {
3806           if (code == PREINCREMENT_EXPR)
3807             errstring ="no pre-increment operator for type";
3808           else if (code == POSTINCREMENT_EXPR)
3809             errstring ="no post-increment operator for type";
3810           else if (code == PREDECREMENT_EXPR)
3811             errstring ="no pre-decrement operator for type";
3812           else
3813             errstring ="no post-decrement operator for type";
3814           break;
3815         }
3816
3817       /* Report something read-only.  */
3818
3819       if (CP_TYPE_CONST_P (TREE_TYPE (arg))
3820           || TREE_READONLY (arg))
3821         readonly_error (arg, ((code == PREINCREMENT_EXPR
3822                                || code == POSTINCREMENT_EXPR)
3823                               ? "increment" : "decrement"),
3824                         0);
3825
3826       {
3827         tree inc;
3828         tree result_type = TREE_TYPE (arg);
3829
3830         arg = get_unwidened (arg, 0);
3831         argtype = TREE_TYPE (arg);
3832
3833         /* ARM $5.2.5 last annotation says this should be forbidden.  */
3834         if (TREE_CODE (argtype) == ENUMERAL_TYPE)
3835           pedwarn ("ISO C++ forbids %sing an enum",
3836                    (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
3837                    ? "increment" : "decrement");
3838
3839         /* Compute the increment.  */
3840
3841         if (TREE_CODE (argtype) == POINTER_TYPE)
3842           {
3843             tree type = complete_type (TREE_TYPE (argtype));
3844
3845             if (!COMPLETE_OR_VOID_TYPE_P (type))
3846               error ("cannot %s a pointer to incomplete type `%T'",
3847                         ((code == PREINCREMENT_EXPR
3848                           || code == POSTINCREMENT_EXPR)
3849                          ? "increment" : "decrement"), TREE_TYPE (argtype));
3850             else if ((pedantic || warn_pointer_arith)
3851                      && !TYPE_PTROB_P (argtype))
3852               pedwarn ("ISO C++ forbids %sing a pointer of type `%T'",
3853                           ((code == PREINCREMENT_EXPR
3854                             || code == POSTINCREMENT_EXPR)
3855                            ? "increment" : "decrement"), argtype);
3856             inc = cxx_sizeof_nowarn (TREE_TYPE (argtype));
3857           }
3858         else
3859           inc = integer_one_node;
3860
3861         inc = cp_convert (argtype, inc);
3862
3863         /* Handle incrementing a cast-expression.  */
3864
3865         switch (TREE_CODE (arg))
3866           {
3867           case NOP_EXPR:
3868           case CONVERT_EXPR:
3869           case FLOAT_EXPR:
3870           case FIX_TRUNC_EXPR:
3871           case FIX_FLOOR_EXPR:
3872           case FIX_ROUND_EXPR:
3873           case FIX_CEIL_EXPR:
3874             {
3875               tree incremented, modify, value, compound;
3876               if (! lvalue_p (arg) && pedantic)
3877                 pedwarn ("cast to non-reference type used as lvalue");
3878               arg = stabilize_reference (arg);
3879               if (code == PREINCREMENT_EXPR || code == PREDECREMENT_EXPR)
3880                 value = arg;
3881               else
3882                 value = save_expr (arg);
3883               incremented = build (((code == PREINCREMENT_EXPR
3884                                      || code == POSTINCREMENT_EXPR)
3885                                     ? PLUS_EXPR : MINUS_EXPR),
3886                                    argtype, value, inc);
3887
3888               modify = build_modify_expr (arg, NOP_EXPR, incremented);
3889               compound = build (COMPOUND_EXPR, TREE_TYPE (arg), modify, value);
3890
3891               /* Eliminate warning about unused result of + or -.  */
3892               TREE_NO_WARNING (compound) = 1;
3893               return compound;
3894             }
3895
3896           default:
3897             break;
3898           }
3899
3900         /* Complain about anything else that is not a true lvalue.  */
3901         if (!lvalue_or_else (arg, ((code == PREINCREMENT_EXPR
3902                                     || code == POSTINCREMENT_EXPR)
3903                                    ? "increment" : "decrement")))
3904           return error_mark_node;
3905
3906         /* Forbid using -- on `bool'.  */
3907         if (TREE_TYPE (arg) == boolean_type_node)
3908           {
3909             if (code == POSTDECREMENT_EXPR || code == PREDECREMENT_EXPR)
3910               {
3911                 error ("invalid use of `--' on bool variable `%D'", arg);
3912                 return error_mark_node;
3913               }
3914             val = boolean_increment (code, arg);
3915           }
3916         else
3917           val = build (code, TREE_TYPE (arg), arg, inc);
3918
3919         TREE_SIDE_EFFECTS (val) = 1;
3920         return cp_convert (result_type, val);
3921       }
3922
3923     case ADDR_EXPR:
3924       /* Note that this operation never does default_conversion
3925          regardless of NOCONVERT.  */
3926
3927       argtype = lvalue_type (arg);
3928
3929       if (TREE_CODE (arg) == OFFSET_REF)
3930         goto offset_ref;
3931
3932       if (TREE_CODE (argtype) == REFERENCE_TYPE)
3933         {
3934           tree type = build_pointer_type (TREE_TYPE (argtype));
3935           arg = build1 (CONVERT_EXPR, type, arg);
3936           return arg;
3937         }
3938       else if (pedantic && DECL_MAIN_P (arg))
3939         /* ARM $3.4 */
3940         pedwarn ("ISO C++ forbids taking address of function `::main'");
3941
3942       /* Let &* cancel out to simplify resulting code.  */
3943       if (TREE_CODE (arg) == INDIRECT_REF)
3944         {
3945           /* We don't need to have `current_class_ptr' wrapped in a
3946              NON_LVALUE_EXPR node.  */
3947           if (arg == current_class_ref)
3948             return current_class_ptr;
3949
3950           arg = TREE_OPERAND (arg, 0);
3951           if (TREE_CODE (TREE_TYPE (arg)) == REFERENCE_TYPE)
3952             {
3953               tree type = build_pointer_type (TREE_TYPE (TREE_TYPE (arg)));
3954               arg = build1 (CONVERT_EXPR, type, arg);
3955             }
3956           else if (lvalue_p (arg))
3957             /* Don't let this be an lvalue.  */
3958             return non_lvalue (arg);
3959           return arg;
3960         }
3961
3962       /* For &x[y], return x+y.  But, in a template, ARG may be an
3963          ARRAY_REF representing a non-dependent expression.  In that
3964          case, there may be an overloaded "operator []" that will be
3965          chosen at instantiation time; we must not try to optimize
3966          here.  */
3967       if (TREE_CODE (arg) == ARRAY_REF && !processing_template_decl)
3968         {
3969           if (!cxx_mark_addressable (TREE_OPERAND (arg, 0)))
3970             return error_mark_node;
3971           return cp_build_binary_op (PLUS_EXPR, TREE_OPERAND (arg, 0),
3972                                      TREE_OPERAND (arg, 1));
3973         }
3974
3975       /* Uninstantiated types are all functions.  Taking the
3976          address of a function is a no-op, so just return the
3977          argument.  */
3978
3979       if (TREE_CODE (arg) == IDENTIFIER_NODE
3980           && IDENTIFIER_OPNAME_P (arg))
3981         {
3982           abort ();
3983           /* We don't know the type yet, so just work around the problem.
3984              We know that this will resolve to an lvalue.  */
3985           return build1 (ADDR_EXPR, unknown_type_node, arg);
3986         }
3987
3988       if (TREE_CODE (arg) == COMPONENT_REF && type_unknown_p (arg)
3989           && !really_overloaded_fn (TREE_OPERAND (arg, 1)))
3990         {
3991           /* They're trying to take the address of a unique non-static
3992              member function.  This is ill-formed (except in MS-land),
3993              but let's try to DTRT.
3994              Note: We only handle unique functions here because we don't
3995              want to complain if there's a static overload; non-unique
3996              cases will be handled by instantiate_type.  But we need to
3997              handle this case here to allow casts on the resulting PMF.
3998              We could defer this in non-MS mode, but it's easier to give
3999              a useful error here.  */
4000
4001           /* Inside constant member functions, the `this' pointer
4002              contains an extra const qualifier.  TYPE_MAIN_VARIANT
4003              is used here to remove this const from the diagnostics
4004              and the created OFFSET_REF.  */
4005           tree base = TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg, 0)));
4006           tree name = DECL_NAME (get_first_fn (TREE_OPERAND (arg, 1)));
4007
4008           if (! flag_ms_extensions)
4009             {
4010               if (current_class_type
4011                   && TREE_OPERAND (arg, 0) == current_class_ref)
4012                 /* An expression like &memfn.  */
4013                 pedwarn ("ISO C++ forbids taking the address of an unqualified"
4014                          " or parenthesized non-static member function to form"
4015                          " a pointer to member function.  Say `&%T::%D'",
4016                          base, name);
4017               else
4018                 pedwarn ("ISO C++ forbids taking the address of a bound member"
4019                          " function to form a pointer to member function."
4020                          "  Say `&%T::%D'",
4021                          base, name);
4022             }
4023           arg = build_offset_ref (base, name, /*address_p=*/true);
4024         }
4025
4026     offset_ref:
4027       if (type_unknown_p (arg))
4028         return build1 (ADDR_EXPR, unknown_type_node, arg);
4029
4030       /* Handle complex lvalues (when permitted)
4031          by reduction to simpler cases.  */
4032       val = unary_complex_lvalue (code, arg);
4033       if (val != 0)
4034         return val;
4035
4036       switch (TREE_CODE (arg))
4037         {
4038         case NOP_EXPR:
4039         case CONVERT_EXPR:
4040         case FLOAT_EXPR:
4041         case FIX_TRUNC_EXPR:
4042         case FIX_FLOOR_EXPR:
4043         case FIX_ROUND_EXPR:
4044         case FIX_CEIL_EXPR:
4045           if (! lvalue_p (arg) && pedantic)
4046             pedwarn ("ISO C++ forbids taking the address of a cast to a non-lvalue expression");
4047           break;
4048
4049         case OVERLOAD:
4050           arg = OVL_CURRENT (arg);
4051           break;
4052
4053         default:
4054           break;
4055         }
4056
4057       /* Allow the address of a constructor if all the elements
4058          are constant.  */
4059       if (TREE_CODE (arg) == CONSTRUCTOR && TREE_HAS_CONSTRUCTOR (arg)
4060           && TREE_CONSTANT (arg))
4061         ;
4062       /* Anything not already handled and not a true memory reference
4063          is an error.  */
4064       else if (TREE_CODE (argtype) != FUNCTION_TYPE
4065                && TREE_CODE (argtype) != METHOD_TYPE
4066                && !lvalue_or_else (arg, "unary `&'"))
4067         return error_mark_node;
4068
4069       if (argtype != error_mark_node)
4070         argtype = build_pointer_type (argtype);
4071
4072       {
4073         tree addr;
4074
4075         if (TREE_CODE (arg) != COMPONENT_REF
4076             /* Inside a template, we are processing a non-dependent
4077                expression so we can just form an ADDR_EXPR with the
4078                correct type.  */
4079             || processing_template_decl)
4080           addr = build_address (arg);
4081         else if (TREE_CODE (TREE_OPERAND (arg, 1)) == BASELINK)
4082           {
4083             tree fn = BASELINK_FUNCTIONS (TREE_OPERAND (arg, 1));
4084
4085             /* We can only get here with a single static member
4086                function.  */
4087             my_friendly_assert (TREE_CODE (fn) == FUNCTION_DECL
4088                                 && DECL_STATIC_FUNCTION_P (fn),
4089                                 20030906);
4090             mark_used (fn);
4091             addr = build_address (fn);
4092             if (TREE_SIDE_EFFECTS (TREE_OPERAND (arg, 0)))
4093               /* Do not lose object's side effects.  */
4094               addr = build (COMPOUND_EXPR, TREE_TYPE (addr),
4095                             TREE_OPERAND (arg, 0), addr);
4096           }
4097         else if (DECL_C_BIT_FIELD (TREE_OPERAND (arg, 1)))
4098           {
4099             error ("attempt to take address of bit-field structure member `%D'",
4100                    TREE_OPERAND (arg, 1));
4101             return error_mark_node;
4102           }
4103         else
4104           {
4105             /* Unfortunately we cannot just build an address
4106                expression here, because we would not handle
4107                address-constant-expressions or offsetof correctly.  */
4108             tree field = TREE_OPERAND (arg, 1);
4109             tree rval = build_unary_op (ADDR_EXPR, TREE_OPERAND (arg, 0), 0);
4110             tree binfo = lookup_base (TREE_TYPE (TREE_TYPE (rval)),
4111                                       decl_type_context (field),
4112                                       ba_check, NULL);
4113
4114             rval = build_base_path (PLUS_EXPR, rval, binfo, 1);
4115             rval = build_nop (argtype, rval);
4116             addr = fold (build (PLUS_EXPR, argtype, rval,
4117                                 cp_convert (argtype, byte_position (field))));
4118           }
4119
4120         if (TREE_CODE (argtype) == POINTER_TYPE
4121             && TREE_CODE (TREE_TYPE (argtype)) == METHOD_TYPE)
4122           {
4123             build_ptrmemfunc_type (argtype);
4124             addr = build_ptrmemfunc (argtype, addr, 0);
4125           }
4126
4127         return addr;
4128       }
4129
4130     default:
4131       break;
4132     }
4133
4134   if (!errstring)
4135     {
4136       if (argtype == 0)
4137         argtype = TREE_TYPE (arg);
4138       return fold (build1 (code, argtype, arg));
4139     }
4140
4141   error ("%s", errstring);
4142   return error_mark_node;
4143 }
4144
4145 /* Apply unary lvalue-demanding operator CODE to the expression ARG
4146    for certain kinds of expressions which are not really lvalues
4147    but which we can accept as lvalues.
4148
4149    If ARG is not a kind of expression we can handle, return zero.  */
4150
4151 tree
4152 unary_complex_lvalue (enum tree_code code, tree arg)
4153 {
4154   /* Handle (a, b) used as an "lvalue".  */
4155   if (TREE_CODE (arg) == COMPOUND_EXPR)
4156     {
4157       tree real_result = build_unary_op (code, TREE_OPERAND (arg, 1), 0);
4158       return build (COMPOUND_EXPR, TREE_TYPE (real_result),
4159                     TREE_OPERAND (arg, 0), real_result);
4160     }
4161
4162   /* Handle (a ? b : c) used as an "lvalue".  */
4163   if (TREE_CODE (arg) == COND_EXPR
4164       || TREE_CODE (arg) == MIN_EXPR || TREE_CODE (arg) == MAX_EXPR)
4165     return rationalize_conditional_expr (code, arg);
4166
4167   /* Handle (a = b), (++a), and (--a) used as an "lvalue".  */
4168   if (TREE_CODE (arg) == MODIFY_EXPR
4169       || TREE_CODE (arg) == PREINCREMENT_EXPR
4170       || TREE_CODE (arg) == PREDECREMENT_EXPR)
4171     {
4172       tree lvalue = TREE_OPERAND (arg, 0);
4173       if (TREE_SIDE_EFFECTS (lvalue))
4174         {
4175           lvalue = stabilize_reference (lvalue);
4176           arg = build (TREE_CODE (arg), TREE_TYPE (arg),
4177                        lvalue, TREE_OPERAND (arg, 1));
4178         }
4179       return unary_complex_lvalue
4180         (code, build (COMPOUND_EXPR, TREE_TYPE (lvalue), arg, lvalue));
4181     }
4182
4183   if (code != ADDR_EXPR)
4184     return 0;
4185
4186   /* Handle (a = b) used as an "lvalue" for `&'.  */
4187   if (TREE_CODE (arg) == MODIFY_EXPR
4188       || TREE_CODE (arg) == INIT_EXPR)
4189     {
4190       tree real_result = build_unary_op (code, TREE_OPERAND (arg, 0), 0);
4191       arg = build (COMPOUND_EXPR, TREE_TYPE (real_result), arg, real_result);
4192       TREE_NO_WARNING (arg) = 1;
4193       return arg;
4194     }
4195
4196   if (TREE_CODE (TREE_TYPE (arg)) == FUNCTION_TYPE
4197       || TREE_CODE (TREE_TYPE (arg)) == METHOD_TYPE
4198       || TREE_CODE (arg) == OFFSET_REF)
4199     {
4200       tree t;
4201
4202       my_friendly_assert (TREE_CODE (arg) != SCOPE_REF, 313);
4203
4204       if (TREE_CODE (arg) != OFFSET_REF)
4205         return 0;
4206
4207       t = TREE_OPERAND (arg, 1);
4208
4209       /* Check all this code for right semantics.  */
4210       if (TREE_CODE (t) == FUNCTION_DECL)
4211         {
4212           if (DECL_DESTRUCTOR_P (t))
4213             error ("taking address of destructor");
4214           return build_unary_op (ADDR_EXPR, t, 0);
4215         }
4216       if (TREE_CODE (t) == VAR_DECL)
4217         return build_unary_op (ADDR_EXPR, t, 0);
4218       else
4219         {
4220           tree type;
4221
4222           if (TREE_OPERAND (arg, 0)
4223               && ! is_dummy_object (TREE_OPERAND (arg, 0))
4224               && TREE_CODE (t) != FIELD_DECL)
4225             {
4226               error ("taking address of bound pointer-to-member expression");
4227               return error_mark_node;
4228             }
4229           if (!PTRMEM_OK_P (arg))
4230             return build_unary_op (code, arg, 0);
4231
4232           if (TREE_CODE (TREE_TYPE (t)) == REFERENCE_TYPE)
4233             {
4234               error ("cannot create pointer to reference member `%D'", t);
4235               return error_mark_node;
4236             }
4237
4238           type = build_ptrmem_type (context_for_name_lookup (t),
4239                                     TREE_TYPE (t));
4240           t = make_ptrmem_cst (type, TREE_OPERAND (arg, 1));
4241           return t;
4242         }
4243     }
4244
4245
4246   /* We permit compiler to make function calls returning
4247      objects of aggregate type look like lvalues.  */
4248   {
4249     tree targ = arg;
4250
4251     if (TREE_CODE (targ) == SAVE_EXPR)
4252       targ = TREE_OPERAND (targ, 0);
4253
4254     if (TREE_CODE (targ) == CALL_EXPR && IS_AGGR_TYPE (TREE_TYPE (targ)))
4255       {
4256         if (TREE_CODE (arg) == SAVE_EXPR)
4257           targ = arg;
4258         else
4259           targ = build_cplus_new (TREE_TYPE (arg), arg);
4260         return build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (arg)), targ);
4261       }
4262
4263     if (TREE_CODE (arg) == SAVE_EXPR && TREE_CODE (targ) == INDIRECT_REF)
4264       return build (SAVE_EXPR, build_pointer_type (TREE_TYPE (arg)),
4265                      TREE_OPERAND (targ, 0), current_function_decl, NULL);
4266   }
4267
4268   /* Don't let anything else be handled specially.  */
4269   return 0;
4270 }
4271 \f
4272 /* Mark EXP saying that we need to be able to take the
4273    address of it; it should not be allocated in a register.
4274    Value is true if successful.
4275
4276    C++: we do not allow `current_class_ptr' to be addressable.  */
4277
4278 bool
4279 cxx_mark_addressable (tree exp)
4280 {
4281   tree x = exp;
4282
4283   while (1)
4284     switch (TREE_CODE (x))
4285       {
4286       case ADDR_EXPR:
4287       case COMPONENT_REF:
4288       case ARRAY_REF:
4289       case REALPART_EXPR:
4290       case IMAGPART_EXPR:
4291         x = TREE_OPERAND (x, 0);
4292         break;
4293
4294       case PARM_DECL:
4295         if (x == current_class_ptr)
4296           {
4297             error ("cannot take the address of `this', which is an rvalue expression");
4298             TREE_ADDRESSABLE (x) = 1; /* so compiler doesn't die later.  */
4299             return true;
4300           }
4301         /* Fall through.  */
4302
4303       case VAR_DECL:
4304         /* Caller should not be trying to mark initialized
4305            constant fields addressable.  */
4306         my_friendly_assert (DECL_LANG_SPECIFIC (x) == 0
4307                             || DECL_IN_AGGR_P (x) == 0
4308                             || TREE_STATIC (x)
4309                             || DECL_EXTERNAL (x), 314);
4310         /* Fall through.  */
4311
4312       case CONST_DECL:
4313       case RESULT_DECL:
4314         if (DECL_REGISTER (x) && !TREE_ADDRESSABLE (x)
4315             && !DECL_ARTIFICIAL (x) && extra_warnings)
4316           warning ("address requested for `%D', which is declared `register'",
4317                       x);
4318         TREE_ADDRESSABLE (x) = 1;
4319         return true;
4320
4321       case FUNCTION_DECL:
4322         TREE_ADDRESSABLE (x) = 1;
4323         return true;
4324
4325       case CONSTRUCTOR:
4326         TREE_ADDRESSABLE (x) = 1;
4327         return true;
4328
4329       case TARGET_EXPR:
4330         TREE_ADDRESSABLE (x) = 1;
4331         cxx_mark_addressable (TREE_OPERAND (x, 0));
4332         return true;
4333
4334       default:
4335         return true;
4336     }
4337 }
4338 \f
4339 /* Build and return a conditional expression IFEXP ? OP1 : OP2.  */
4340
4341 tree
4342 build_x_conditional_expr (tree ifexp, tree op1, tree op2)
4343 {
4344   tree orig_ifexp = ifexp;
4345   tree orig_op1 = op1;
4346   tree orig_op2 = op2;
4347   tree expr;
4348
4349   if (processing_template_decl)
4350     {
4351       /* The standard says that the expression is type-dependent if
4352          IFEXP is type-dependent, even though the eventual type of the
4353          expression doesn't dependent on IFEXP.  */
4354       if (type_dependent_expression_p (ifexp)
4355           /* As a GNU extension, the middle operand may be omitted.  */
4356           || (op1 && type_dependent_expression_p (op1))
4357           || type_dependent_expression_p (op2))
4358         return build_min_nt (COND_EXPR, ifexp, op1, op2);
4359       ifexp = build_non_dependent_expr (ifexp);
4360       if (op1)
4361         op1 = build_non_dependent_expr (op1);
4362       op2 = build_non_dependent_expr (op2);
4363     }
4364
4365   expr = build_conditional_expr (ifexp, op1, op2);
4366   if (processing_template_decl && expr != error_mark_node)
4367     return build_min_non_dep (COND_EXPR, expr,
4368                               orig_ifexp, orig_op1, orig_op2);
4369   return expr;
4370 }
4371 \f
4372 /* Given a list of expressions, return a compound expression
4373    that performs them all and returns the value of the last of them.  */
4374
4375 tree build_x_compound_expr_from_list (tree list, const char *msg)
4376 {
4377   tree expr = TREE_VALUE (list);
4378
4379   if (TREE_CHAIN (list))
4380     {
4381       if (msg)
4382         pedwarn ("%s expression list treated as compound expression", msg);
4383
4384       for (list = TREE_CHAIN (list); list; list = TREE_CHAIN (list))
4385         expr = build_x_compound_expr (expr, TREE_VALUE (list));
4386     }
4387
4388   return expr;
4389 }
4390
4391 /* Handle overloading of the ',' operator when needed.  */
4392
4393 tree
4394 build_x_compound_expr (tree op1, tree op2)
4395 {
4396   tree result;
4397   tree orig_op1 = op1;
4398   tree orig_op2 = op2;
4399
4400   if (processing_template_decl)
4401     {
4402       if (type_dependent_expression_p (op1)
4403           || type_dependent_expression_p (op2))
4404         return build_min_nt (COMPOUND_EXPR, op1, op2);
4405       op1 = build_non_dependent_expr (op1);
4406       op2 = build_non_dependent_expr (op2);
4407     }
4408
4409   result = build_new_op (COMPOUND_EXPR, LOOKUP_NORMAL, op1, op2, NULL_TREE,
4410                          /*overloaded_p=*/NULL);
4411   if (!result)
4412     result = build_compound_expr (op1, op2);
4413
4414   if (processing_template_decl && result != error_mark_node)
4415     return build_min_non_dep (COMPOUND_EXPR, result, orig_op1, orig_op2);
4416
4417   return result;
4418 }
4419
4420 /* Build a compound expression.  */
4421
4422 tree
4423 build_compound_expr (tree lhs, tree rhs)
4424 {
4425   lhs = decl_constant_value (lhs);
4426   lhs = convert_to_void (lhs, "left-hand operand of comma");
4427
4428   if (lhs == error_mark_node || rhs == error_mark_node)
4429     return error_mark_node;
4430
4431   if (TREE_CODE (rhs) == TARGET_EXPR)
4432     {
4433       /* If the rhs is a TARGET_EXPR, then build the compound
4434          expression inside the target_expr's initializer. This
4435          helps the compiler to eliminate unnecessary temporaries.  */
4436       tree init = TREE_OPERAND (rhs, 1);
4437
4438       init = build (COMPOUND_EXPR, TREE_TYPE (init), lhs, init);
4439       TREE_OPERAND (rhs, 1) = init;
4440
4441       return rhs;
4442     }
4443
4444   return build (COMPOUND_EXPR, TREE_TYPE (rhs), lhs, rhs);
4445 }
4446
4447 /* Issue an error message if casting from SRC_TYPE to DEST_TYPE casts
4448    away constness.  DESCRIPTION explains what operation is taking
4449    place.  */
4450
4451 static void
4452 check_for_casting_away_constness (tree src_type, tree dest_type,
4453                                   const char *description)
4454 {
4455   if (casts_away_constness (src_type, dest_type))
4456     error ("%s from type `%T' to type `%T' casts away constness",
4457            description, src_type, dest_type);
4458 }
4459
4460 /* Return an expression representing static_cast<TYPE>(EXPR).  */
4461
4462 tree
4463 build_static_cast (tree type, tree expr)
4464 {
4465   tree intype;
4466   tree result;
4467
4468   if (type == error_mark_node || expr == error_mark_node)
4469     return error_mark_node;
4470
4471   if (processing_template_decl)
4472     {
4473       expr = build_min (STATIC_CAST_EXPR, type, expr);
4474       /* We don't know if it will or will not have side effects.  */
4475       TREE_SIDE_EFFECTS (expr) = 1;
4476       return expr;
4477     }
4478
4479   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
4480      Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
4481   if (TREE_CODE (type) != REFERENCE_TYPE
4482       && TREE_CODE (expr) == NOP_EXPR
4483       && TREE_TYPE (expr) == TREE_TYPE (TREE_OPERAND (expr, 0)))
4484     expr = TREE_OPERAND (expr, 0);
4485
4486   intype = TREE_TYPE (expr);
4487
4488   /* [expr.static.cast]
4489
4490      An lvalue of type "cv1 B", where B is a class type, can be cast
4491      to type "reference to cv2 D", where D is a class derived (clause
4492      _class.derived_) from B, if a valid standard conversion from
4493      "pointer to D" to "pointer to B" exists (_conv.ptr_), cv2 is the
4494      same cv-qualification as, or greater cv-qualification than, cv1,
4495      and B is not a virtual base class of D.  */
4496   /* We check this case before checking the validity of "TYPE t =
4497      EXPR;" below because for this case:
4498
4499        struct B {};
4500        struct D : public B { D(const B&); };
4501        extern B& b;
4502        void f() { static_cast<const D&>(b); }
4503
4504      we want to avoid constructing a new D.  The standard is not
4505      completely clear about this issue, but our interpretation is
4506      consistent with other compilers.  */
4507   if (TREE_CODE (type) == REFERENCE_TYPE
4508       && CLASS_TYPE_P (TREE_TYPE (type))
4509       && CLASS_TYPE_P (intype)
4510       && real_lvalue_p (expr)
4511       && DERIVED_FROM_P (intype, TREE_TYPE (type))
4512       && can_convert (build_pointer_type (TYPE_MAIN_VARIANT (intype)),
4513                       build_pointer_type (TYPE_MAIN_VARIANT
4514                                           (TREE_TYPE (type))))
4515       && at_least_as_qualified_p (TREE_TYPE (type), intype))
4516     {
4517       /* There is a standard conversion from "D*" to "B*" even if "B"
4518          is ambiguous or inaccessible.  Therefore, we ask lookup_base
4519          to check these conditions.  */
4520       tree base = lookup_base (TREE_TYPE (type), intype, ba_check, NULL);
4521
4522       /* Convert from "B*" to "D*".  This function will check that "B"
4523          is not a virtual base of "D".  */
4524       expr = build_base_path (MINUS_EXPR, build_address (expr),
4525                               base, /*nonnull=*/false);
4526       /* Convert the pointer to a reference -- but then remember that
4527          there are no expressions with reference type in C++.  */
4528       return convert_from_reference (build_nop (type, expr));
4529     }
4530
4531   /* [expr.static.cast]
4532
4533      An expression e can be explicitly converted to a type T using a
4534      static_cast of the form static_cast<T>(e) if the declaration T
4535      t(e);" is well-formed, for some invented temporary variable
4536      t.  */
4537   result = perform_direct_initialization_if_possible (type, expr);
4538   if (result)
4539     {
4540       result = convert_from_reference (result);
4541       /* [expr.static.cast]
4542
4543          If T is a reference type, the result is an lvalue; otherwise,
4544          the result is an rvalue.  */
4545       if (TREE_CODE (type) != REFERENCE_TYPE
4546           && real_lvalue_p (result))
4547         result = build1 (NON_LVALUE_EXPR, TREE_TYPE (result), result);
4548       return result;
4549     }
4550
4551   /* [expr.static.cast]
4552
4553      Any expression can be explicitly converted to type cv void.  */
4554   if (TREE_CODE (type) == VOID_TYPE)
4555     return convert_to_void (expr, /*implicit=*/NULL);
4556
4557   /* [expr.static.cast]
4558
4559      The inverse of any standard conversion sequence (clause _conv_),
4560      other than the lvalue-to-rvalue (_conv.lval_), array-to-pointer
4561      (_conv.array_), function-to-pointer (_conv.func_), and boolean
4562      (_conv.bool_) conversions, can be performed explicitly using
4563      static_cast subject to the restriction that the explicit
4564      conversion does not cast away constness (_expr.const.cast_), and
4565      the following additional rules for specific cases:  */
4566   /* For reference, the conversions not excluded are: integral
4567      promotions, floating point promotion, integral conversions,
4568      floating point conversions, floating-integral conversions,
4569      pointer conversions, and pointer to member conversions.  */
4570   if ((ARITHMETIC_TYPE_P (type) && ARITHMETIC_TYPE_P (intype))
4571       /* DR 128
4572
4573          A value of integral _or enumeration_ type can be explicitly
4574          converted to an enumeration type.  */
4575       || (INTEGRAL_OR_ENUMERATION_TYPE_P (type)
4576           && INTEGRAL_OR_ENUMERATION_TYPE_P (intype)))
4577     /* Really, build_c_cast should defer to this function rather
4578        than the other way around.  */
4579     return build_c_cast (type, expr);
4580
4581   if (TYPE_PTR_P (type) && TYPE_PTR_P (intype)
4582       && CLASS_TYPE_P (TREE_TYPE (type))
4583       && CLASS_TYPE_P (TREE_TYPE (intype))
4584       && can_convert (build_pointer_type (TYPE_MAIN_VARIANT
4585                                           (TREE_TYPE (intype))),
4586                       build_pointer_type (TYPE_MAIN_VARIANT
4587                                           (TREE_TYPE (type)))))
4588     {
4589       tree base;
4590
4591       check_for_casting_away_constness (intype, type, "static_cast");
4592       base = lookup_base (TREE_TYPE (type), TREE_TYPE (intype), ba_check,
4593                           NULL);
4594       return build_base_path (MINUS_EXPR, expr, base, /*nonnull=*/false);
4595     }
4596
4597   if ((TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
4598       || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
4599     {
4600       tree c1;
4601       tree c2;
4602       tree t1;
4603       tree t2;
4604
4605       c1 = TYPE_PTRMEM_CLASS_TYPE (intype);
4606       c2 = TYPE_PTRMEM_CLASS_TYPE (type);
4607
4608       if (TYPE_PTRMEM_P (type))
4609         {
4610           t1 = (build_ptrmem_type
4611                 (c1,
4612                  TYPE_MAIN_VARIANT (TYPE_PTRMEM_POINTED_TO_TYPE (intype))));
4613           t2 = (build_ptrmem_type
4614                 (c2,
4615                  TYPE_MAIN_VARIANT (TYPE_PTRMEM_POINTED_TO_TYPE (type))));
4616         }
4617       else
4618         {
4619           t1 = intype;
4620           t2 = type;
4621         }
4622       if (can_convert (t1, t2))
4623         {
4624           check_for_casting_away_constness (intype, type, "static_cast");
4625           if (TYPE_PTRMEM_P (type))
4626             {
4627               tree delta;
4628
4629               if (TREE_CODE (expr) == PTRMEM_CST)
4630                 expr = cplus_expand_constant (expr);
4631               delta = get_delta_difference (c1, c2, /*force=*/1);
4632               if (!integer_zerop (delta))
4633                 expr = cp_build_binary_op (PLUS_EXPR,
4634                                            build_nop (ptrdiff_type_node, expr),
4635                                            delta);
4636               return build_nop (type, expr);
4637             }
4638           else
4639             return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr,
4640                                      /*force=*/1);
4641         }
4642     }
4643
4644   /* [expr.static.cast]
4645
4646      An rvalue of type "pointer to cv void" can be explicitly
4647      converted to a pointer to object type.  A value of type pointer
4648      to object converted to "pointer to cv void" and back to the
4649      original pointer type will have its original value.  */
4650   if (TREE_CODE (intype) == POINTER_TYPE
4651       && VOID_TYPE_P (TREE_TYPE (intype))
4652       && TYPE_PTROB_P (type))
4653     {
4654       check_for_casting_away_constness (intype, type, "static_cast");
4655       return build_nop (type, expr);
4656     }
4657
4658   error ("invalid static_cast from type `%T' to type `%T'", intype, type);
4659   return error_mark_node;
4660 }
4661
4662 tree
4663 build_reinterpret_cast (tree type, tree expr)
4664 {
4665   tree intype;
4666
4667   if (type == error_mark_node || expr == error_mark_node)
4668     return error_mark_node;
4669
4670   if (processing_template_decl)
4671     {
4672       tree t = build_min (REINTERPRET_CAST_EXPR, type, expr);
4673
4674       if (!TREE_SIDE_EFFECTS (t)
4675           && type_dependent_expression_p (expr))
4676         /* There might turn out to be side effects inside expr.  */
4677         TREE_SIDE_EFFECTS (t) = 1;
4678       return t;
4679     }
4680
4681   if (TREE_CODE (type) != REFERENCE_TYPE)
4682     {
4683       expr = decay_conversion (expr);
4684
4685       /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
4686          Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
4687       if (TREE_CODE (expr) == NOP_EXPR
4688           && TREE_TYPE (expr) == TREE_TYPE (TREE_OPERAND (expr, 0)))
4689         expr = TREE_OPERAND (expr, 0);
4690     }
4691
4692   intype = TREE_TYPE (expr);
4693
4694   if (TREE_CODE (type) == REFERENCE_TYPE)
4695     {
4696       if (! real_lvalue_p (expr))
4697         {
4698           error ("invalid reinterpret_cast of an rvalue expression of type `%T' to type `%T'", intype, type);
4699           return error_mark_node;
4700         }
4701       expr = build_unary_op (ADDR_EXPR, expr, 0);
4702       if (expr != error_mark_node)
4703         expr = build_reinterpret_cast
4704           (build_pointer_type (TREE_TYPE (type)), expr);
4705       if (expr != error_mark_node)
4706         expr = build_indirect_ref (expr, 0);
4707       return expr;
4708     }
4709   else if (same_type_ignoring_top_level_qualifiers_p (intype, type))
4710     return build_static_cast (type, expr);
4711
4712   if (TYPE_PTR_P (type) && (TREE_CODE (intype) == INTEGER_TYPE
4713                             || TREE_CODE (intype) == ENUMERAL_TYPE))
4714     /* OK */;
4715   else if (TREE_CODE (type) == INTEGER_TYPE && TYPE_PTR_P (intype))
4716     {
4717       if (TYPE_PRECISION (type) < TYPE_PRECISION (intype))
4718         pedwarn ("reinterpret_cast from `%T' to `%T' loses precision",
4719                     intype, type);
4720     }
4721   else if ((TYPE_PTRFN_P (type) && TYPE_PTRFN_P (intype))
4722            || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
4723     {
4724       expr = decl_constant_value (expr);
4725       return fold (build1 (NOP_EXPR, type, expr));
4726     }
4727   else if ((TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
4728            || (TYPE_PTROBV_P (type) && TYPE_PTROBV_P (intype)))
4729     {
4730       check_for_casting_away_constness (intype, type, "reinterpret_cast");
4731       expr = decl_constant_value (expr);
4732       return fold (build1 (NOP_EXPR, type, expr));
4733     }
4734   else if ((TYPE_PTRFN_P (type) && TYPE_PTROBV_P (intype))
4735            || (TYPE_PTRFN_P (intype) && TYPE_PTROBV_P (type)))
4736     {
4737       pedwarn ("ISO C++ forbids casting between pointer-to-function and pointer-to-object");
4738       expr = decl_constant_value (expr);
4739       return fold (build1 (NOP_EXPR, type, expr));
4740     }
4741   else
4742     {
4743       error ("invalid reinterpret_cast from type `%T' to type `%T'",
4744                 intype, type);
4745       return error_mark_node;
4746     }
4747
4748   return cp_convert (type, expr);
4749 }
4750
4751 tree
4752 build_const_cast (tree type, tree expr)
4753 {
4754   tree intype;
4755
4756   if (type == error_mark_node || expr == error_mark_node)
4757     return error_mark_node;
4758
4759   if (processing_template_decl)
4760     {
4761       tree t = build_min (CONST_CAST_EXPR, type, expr);
4762
4763       if (!TREE_SIDE_EFFECTS (t)
4764           && type_dependent_expression_p (expr))
4765         /* There might turn out to be side effects inside expr.  */
4766         TREE_SIDE_EFFECTS (t) = 1;
4767       return t;
4768     }
4769
4770   if (!POINTER_TYPE_P (type) && !TYPE_PTRMEM_P (type))
4771     error ("invalid use of const_cast with type `%T', which is not a pointer, reference, nor a pointer-to-data-member type", type);
4772   else if (TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE)
4773     {
4774       error ("invalid use of const_cast with type `%T', which is a pointer or reference to a function type", type);
4775       return error_mark_node;
4776     }
4777
4778   if (TREE_CODE (type) != REFERENCE_TYPE)
4779     {
4780       expr = decay_conversion (expr);
4781
4782       /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
4783          Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
4784       if (TREE_CODE (expr) == NOP_EXPR
4785           && TREE_TYPE (expr) == TREE_TYPE (TREE_OPERAND (expr, 0)))
4786         expr = TREE_OPERAND (expr, 0);
4787     }
4788
4789   intype = TREE_TYPE (expr);
4790
4791   if (same_type_ignoring_top_level_qualifiers_p (intype, type))
4792     return build_static_cast (type, expr);
4793   else if (TREE_CODE (type) == REFERENCE_TYPE)
4794     {
4795       if (! real_lvalue_p (expr))
4796         {
4797           error ("invalid const_cast of an rvalue of type `%T' to type `%T'", intype, type);
4798           return error_mark_node;
4799         }
4800
4801       if (comp_ptr_ttypes_const (TREE_TYPE (type), intype))
4802         {
4803           expr = build_unary_op (ADDR_EXPR, expr, 0);
4804           expr = build1 (NOP_EXPR, type, expr);
4805           return convert_from_reference (expr);
4806         }
4807     }
4808   else if (((TREE_CODE (type) == POINTER_TYPE
4809              && TREE_CODE (intype) == POINTER_TYPE)
4810             || (TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype)))
4811            && comp_ptr_ttypes_const (TREE_TYPE (type), TREE_TYPE (intype)))
4812     return cp_convert (type, expr);
4813
4814   error ("invalid const_cast from type `%T' to type `%T'", intype, type);
4815   return error_mark_node;
4816 }
4817
4818 /* Build an expression representing a cast to type TYPE of expression EXPR.
4819
4820    ALLOW_NONCONVERTING is true if we should allow non-converting constructors
4821    when doing the cast.  */
4822
4823 tree
4824 build_c_cast (tree type, tree expr)
4825 {
4826   tree value = expr;
4827   tree otype;
4828
4829   if (type == error_mark_node || expr == error_mark_node)
4830     return error_mark_node;
4831
4832   if (processing_template_decl)
4833     {
4834       tree t = build_min (CAST_EXPR, type,
4835                           tree_cons (NULL_TREE, value, NULL_TREE));
4836       /* We don't know if it will or will not have side effects.  */
4837       TREE_SIDE_EFFECTS (t) = 1;
4838       return t;
4839     }
4840
4841   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
4842      Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
4843   if (TREE_CODE (type) != REFERENCE_TYPE
4844       && TREE_CODE (value) == NOP_EXPR
4845       && TREE_TYPE (value) == TREE_TYPE (TREE_OPERAND (value, 0)))
4846     value = TREE_OPERAND (value, 0);
4847
4848   if (TREE_CODE (type) == ARRAY_TYPE)
4849     {
4850       /* Allow casting from T1* to T2[] because Cfront allows it.
4851          NIHCL uses it. It is not valid ISO C++ however.  */
4852       if (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE)
4853         {
4854           pedwarn ("ISO C++ forbids casting to an array type `%T'", type);
4855           type = build_pointer_type (TREE_TYPE (type));
4856         }
4857       else
4858         {
4859           error ("ISO C++ forbids casting to an array type `%T'", type);
4860           return error_mark_node;
4861         }
4862     }
4863
4864   if (TREE_CODE (type) == FUNCTION_TYPE
4865       || TREE_CODE (type) == METHOD_TYPE)
4866     {
4867       error ("invalid cast to function type `%T'", type);
4868       return error_mark_node;
4869     }
4870
4871   if (TREE_CODE (type) == VOID_TYPE)
4872     {
4873       /* Conversion to void does not cause any of the normal function to
4874        * pointer, array to pointer and lvalue to rvalue decays.  */
4875
4876       value = convert_to_void (value, /*implicit=*/NULL);
4877       return value;
4878     }
4879
4880   if (!complete_type_or_else (type, NULL_TREE))
4881     return error_mark_node;
4882
4883   /* Convert functions and arrays to pointers and
4884      convert references to their expanded types,
4885      but don't convert any other types.  If, however, we are
4886      casting to a class type, there's no reason to do this: the
4887      cast will only succeed if there is a converting constructor,
4888      and the default conversions will be done at that point.  In
4889      fact, doing the default conversion here is actually harmful
4890      in cases like this:
4891
4892      typedef int A[2];
4893      struct S { S(const A&); };
4894
4895      since we don't want the array-to-pointer conversion done.  */
4896   if (!IS_AGGR_TYPE (type))
4897     {
4898       if (TREE_CODE (TREE_TYPE (value)) == FUNCTION_TYPE
4899           || (TREE_CODE (TREE_TYPE (value)) == METHOD_TYPE
4900               /* Don't do the default conversion on a ->* expression.  */
4901               && ! (TREE_CODE (type) == POINTER_TYPE
4902                     && bound_pmf_p (value)))
4903           || TREE_CODE (TREE_TYPE (value)) == ARRAY_TYPE
4904           || TREE_CODE (TREE_TYPE (value)) == REFERENCE_TYPE)
4905         value = decay_conversion (value);
4906     }
4907   else if (TREE_CODE (TREE_TYPE (value)) == REFERENCE_TYPE)
4908     /* However, even for class types, we still need to strip away
4909        the reference type, since the call to convert_force below
4910        does not expect the input expression to be of reference
4911        type.  */
4912     value = convert_from_reference (value);
4913
4914   otype = TREE_TYPE (value);
4915
4916   /* Optionally warn about potentially worrisome casts.  */
4917
4918   if (warn_cast_qual
4919       && TREE_CODE (type) == POINTER_TYPE
4920       && TREE_CODE (otype) == POINTER_TYPE
4921       && !at_least_as_qualified_p (TREE_TYPE (type),
4922                                    TREE_TYPE (otype)))
4923     warning ("cast from `%T' to `%T' discards qualifiers from pointer target type",
4924                 otype, type);
4925
4926   if (TREE_CODE (type) == INTEGER_TYPE
4927       && TYPE_PTR_P (otype)
4928       && TYPE_PRECISION (type) != TYPE_PRECISION (otype))
4929     warning ("cast from pointer to integer of different size");
4930
4931   if (TYPE_PTR_P (type)
4932       && TREE_CODE (otype) == INTEGER_TYPE
4933       && TYPE_PRECISION (type) != TYPE_PRECISION (otype)
4934       /* Don't warn about converting any constant.  */
4935       && !TREE_CONSTANT (value))
4936     warning ("cast to pointer from integer of different size");
4937
4938   if (TREE_CODE (type) == REFERENCE_TYPE)
4939     value = (convert_from_reference
4940              (convert_to_reference (type, value, CONV_C_CAST,
4941                                     LOOKUP_COMPLAIN, NULL_TREE)));
4942   else
4943     {
4944       tree ovalue;
4945
4946       value = decl_constant_value (value);
4947
4948       ovalue = value;
4949       value = convert_force (type, value, CONV_C_CAST);
4950
4951       /* Ignore any integer overflow caused by the cast.  */
4952       if (TREE_CODE (value) == INTEGER_CST)
4953         {
4954           TREE_OVERFLOW (value) = TREE_OVERFLOW (ovalue);
4955
4956           if (TREE_CODE_CLASS (TREE_CODE (ovalue)) == 'c')
4957             TREE_CONSTANT_OVERFLOW (value) = TREE_CONSTANT_OVERFLOW (ovalue);
4958         }
4959     }
4960
4961   /* Warn about possible alignment problems.  Do this here when we will have
4962      instantiated any necessary template types.  */
4963   if (STRICT_ALIGNMENT && warn_cast_align
4964       && TREE_CODE (type) == POINTER_TYPE
4965       && TREE_CODE (otype) == POINTER_TYPE
4966       && TREE_CODE (TREE_TYPE (otype)) != VOID_TYPE
4967       && TREE_CODE (TREE_TYPE (otype)) != FUNCTION_TYPE
4968       && COMPLETE_TYPE_P (TREE_TYPE (otype))
4969       && COMPLETE_TYPE_P (TREE_TYPE (type))
4970       && TYPE_ALIGN (TREE_TYPE (type)) > TYPE_ALIGN (TREE_TYPE (otype)))
4971     warning ("cast from `%T' to `%T' increases required alignment of target type",
4972                 otype, type);
4973
4974     /* Always produce some operator for an explicit cast,
4975        so we can tell (for -pedantic) that the cast is no lvalue.  */
4976   if (TREE_CODE (type) != REFERENCE_TYPE && value == expr
4977       && real_lvalue_p (value))
4978     value = non_lvalue (value);
4979
4980   return value;
4981 }
4982 \f
4983 /* Build an assignment expression of lvalue LHS from value RHS.
4984    MODIFYCODE is the code for a binary operator that we use
4985    to combine the old value of LHS with RHS to get the new value.
4986    Or else MODIFYCODE is NOP_EXPR meaning do a simple assignment.
4987
4988    C++: If MODIFYCODE is INIT_EXPR, then leave references unbashed.  */
4989
4990 tree
4991 build_modify_expr (tree lhs, enum tree_code modifycode, tree rhs)
4992 {
4993   tree result;
4994   tree newrhs = rhs;
4995   tree lhstype = TREE_TYPE (lhs);
4996   tree olhstype = lhstype;
4997   tree olhs = NULL_TREE;
4998   bool plain_assign = (modifycode == NOP_EXPR);
4999
5000   /* Avoid duplicate error messages from operands that had errors.  */
5001   if (lhs == error_mark_node || rhs == error_mark_node)
5002     return error_mark_node;
5003
5004   /* Handle control structure constructs used as "lvalues".  */
5005   switch (TREE_CODE (lhs))
5006     {
5007       /* Handle --foo = 5; as these are valid constructs in C++.  */
5008     case PREDECREMENT_EXPR:
5009     case PREINCREMENT_EXPR:
5010       if (TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 0)))
5011         lhs = build (TREE_CODE (lhs), TREE_TYPE (lhs),
5012                      stabilize_reference (TREE_OPERAND (lhs, 0)),
5013                      TREE_OPERAND (lhs, 1));
5014       return build (COMPOUND_EXPR, lhstype,
5015                     lhs,
5016                     build_modify_expr (TREE_OPERAND (lhs, 0),
5017                                        modifycode, rhs));
5018
5019       /* Handle (a, b) used as an "lvalue".  */
5020     case COMPOUND_EXPR:
5021       newrhs = build_modify_expr (TREE_OPERAND (lhs, 1),
5022                                   modifycode, rhs);
5023       if (newrhs == error_mark_node)
5024         return error_mark_node;
5025       return build (COMPOUND_EXPR, lhstype,
5026                     TREE_OPERAND (lhs, 0), newrhs);
5027
5028     case MODIFY_EXPR:
5029       if (TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 0)))
5030         lhs = build (TREE_CODE (lhs), TREE_TYPE (lhs),
5031                      stabilize_reference (TREE_OPERAND (lhs, 0)),
5032                      TREE_OPERAND (lhs, 1));
5033       newrhs = build_modify_expr (TREE_OPERAND (lhs, 0), modifycode, rhs);
5034       if (newrhs == error_mark_node)
5035         return error_mark_node;
5036       return build (COMPOUND_EXPR, lhstype, lhs, newrhs);
5037
5038       /* Handle (a ? b : c) used as an "lvalue".  */
5039     case COND_EXPR:
5040       {
5041         /* Produce (a ? (b = rhs) : (c = rhs))
5042            except that the RHS goes through a save-expr
5043            so the code to compute it is only emitted once.  */
5044         tree cond;
5045         tree preeval = NULL_TREE;
5046
5047         rhs = stabilize_expr (rhs, &preeval);
5048
5049         /* Check this here to avoid odd errors when trying to convert
5050            a throw to the type of the COND_EXPR.  */
5051         if (!lvalue_or_else (lhs, "assignment"))
5052           return error_mark_node;
5053
5054         cond = build_conditional_expr
5055           (TREE_OPERAND (lhs, 0),
5056            build_modify_expr (cp_convert (TREE_TYPE (lhs),
5057                                           TREE_OPERAND (lhs, 1)),
5058                               modifycode, rhs),
5059            build_modify_expr (cp_convert (TREE_TYPE (lhs),
5060                                           TREE_OPERAND (lhs, 2)),
5061                               modifycode, rhs));
5062
5063         if (cond == error_mark_node)
5064           return cond;
5065         /* Make sure the code to compute the rhs comes out
5066            before the split.  */
5067         if (preeval)
5068           cond = build (COMPOUND_EXPR, TREE_TYPE (lhs), preeval, cond);
5069         return cond;
5070       }
5071
5072     default:
5073       break;
5074     }
5075
5076   if (modifycode == INIT_EXPR)
5077     {
5078       if (TREE_CODE (rhs) == CONSTRUCTOR)
5079         {
5080           if (! same_type_p (TREE_TYPE (rhs), lhstype))
5081             /* Call convert to generate an error; see PR 11063.  */
5082             rhs = convert (lhstype, rhs);
5083           result = build (INIT_EXPR, lhstype, lhs, rhs);
5084           TREE_SIDE_EFFECTS (result) = 1;
5085           return result;
5086         }
5087       else if (! IS_AGGR_TYPE (lhstype))
5088         /* Do the default thing.  */;
5089       else
5090         {
5091           result = build_special_member_call (lhs, complete_ctor_identifier,
5092                                               build_tree_list (NULL_TREE, rhs),
5093                                               lhstype, LOOKUP_NORMAL);
5094           if (result == NULL_TREE)
5095             return error_mark_node;
5096           return result;
5097         }
5098     }
5099   else
5100     {
5101       if (TREE_CODE (lhstype) == REFERENCE_TYPE)
5102         {
5103           lhs = convert_from_reference (lhs);
5104           olhstype = lhstype = TREE_TYPE (lhs);
5105         }
5106       lhs = require_complete_type (lhs);
5107       if (lhs == error_mark_node)
5108         return error_mark_node;
5109
5110       if (modifycode == NOP_EXPR)
5111         {
5112           /* `operator=' is not an inheritable operator.  */
5113           if (! IS_AGGR_TYPE (lhstype))
5114             /* Do the default thing.  */;
5115           else
5116             {
5117               result = build_new_op (MODIFY_EXPR, LOOKUP_NORMAL,
5118                                      lhs, rhs, make_node (NOP_EXPR),
5119                                      /*overloaded_p=*/NULL);
5120               if (result == NULL_TREE)
5121                 return error_mark_node;
5122               return result;
5123             }
5124           lhstype = olhstype;
5125         }
5126       else
5127         {
5128           /* A binary op has been requested.  Combine the old LHS
5129              value with the RHS producing the value we should actually
5130              store into the LHS.  */
5131
5132           my_friendly_assert (!PROMOTES_TO_AGGR_TYPE (lhstype, REFERENCE_TYPE),
5133                               978652);
5134           lhs = stabilize_reference (lhs);
5135           newrhs = cp_build_binary_op (modifycode, lhs, rhs);
5136           if (newrhs == error_mark_node)
5137             {
5138               error ("  in evaluation of `%Q(%#T, %#T)'", modifycode,
5139                      TREE_TYPE (lhs), TREE_TYPE (rhs));
5140               return error_mark_node;
5141             }
5142
5143           /* Now it looks like a plain assignment.  */
5144           modifycode = NOP_EXPR;
5145         }
5146       my_friendly_assert (TREE_CODE (lhstype) != REFERENCE_TYPE, 20011220);
5147       my_friendly_assert (TREE_CODE (TREE_TYPE (newrhs)) != REFERENCE_TYPE,
5148                           20011220);
5149     }
5150
5151   /* The left-hand side must be an lvalue.  */
5152   if (!lvalue_or_else (lhs, "assignment"))
5153     return error_mark_node;
5154
5155   /* Warn about modifying something that is `const'.  Don't warn if
5156      this is initialization.  */
5157   if (modifycode != INIT_EXPR
5158       && (TREE_READONLY (lhs) || CP_TYPE_CONST_P (lhstype)
5159           /* Functions are not modifiable, even though they are
5160              lvalues.  */
5161           || TREE_CODE (TREE_TYPE (lhs)) == FUNCTION_TYPE
5162           || TREE_CODE (TREE_TYPE (lhs)) == METHOD_TYPE
5163           /* If it's an aggregate and any field is const, then it is
5164              effectively const.  */
5165           || (CLASS_TYPE_P (lhstype)
5166               && C_TYPE_FIELDS_READONLY (lhstype))))
5167     readonly_error (lhs, "assignment", 0);
5168
5169   /* If storing into a structure or union member, it has probably been
5170      given type `int'.  Compute the type that would go with the actual
5171      amount of storage the member occupies.  */
5172
5173   if (TREE_CODE (lhs) == COMPONENT_REF
5174       && (TREE_CODE (lhstype) == INTEGER_TYPE
5175           || TREE_CODE (lhstype) == REAL_TYPE
5176           || TREE_CODE (lhstype) == ENUMERAL_TYPE))
5177     {
5178       lhstype = TREE_TYPE (get_unwidened (lhs, 0));
5179
5180       /* If storing in a field that is in actuality a short or narrower
5181          than one, we must store in the field in its actual type.  */
5182
5183       if (lhstype != TREE_TYPE (lhs))
5184         {
5185           /* Avoid warnings converting integral types back into enums for
5186              enum bit fields.  */
5187           if (TREE_CODE (lhstype) == INTEGER_TYPE
5188               && TREE_CODE (olhstype) == ENUMERAL_TYPE)
5189             {
5190               if (TREE_SIDE_EFFECTS (lhs))
5191                 lhs = stabilize_reference (lhs);
5192               olhs = lhs;
5193             }
5194           lhs = copy_node (lhs);
5195           TREE_TYPE (lhs) = lhstype;
5196         }
5197     }
5198
5199   /* Convert new value to destination type.  */
5200
5201   if (TREE_CODE (lhstype) == ARRAY_TYPE)
5202     {
5203       int from_array;
5204
5205       if (!same_or_base_type_p (TYPE_MAIN_VARIANT (lhstype),
5206                                 TYPE_MAIN_VARIANT (TREE_TYPE (rhs))))
5207         {
5208           error ("incompatible types in assignment of `%T' to `%T'",
5209                  TREE_TYPE (rhs), lhstype);
5210           return error_mark_node;
5211         }
5212
5213       /* Allow array assignment in compiler-generated code.  */
5214       if (! DECL_ARTIFICIAL (current_function_decl))
5215         pedwarn ("ISO C++ forbids assignment of arrays");
5216
5217       from_array = TREE_CODE (TREE_TYPE (newrhs)) == ARRAY_TYPE
5218                    ? 1 + (modifycode != INIT_EXPR): 0;
5219       return build_vec_init (lhs, NULL_TREE, newrhs, from_array);
5220     }
5221
5222   if (modifycode == INIT_EXPR)
5223     newrhs = convert_for_initialization (lhs, lhstype, newrhs, LOOKUP_NORMAL,
5224                                          "initialization", NULL_TREE, 0);
5225   else
5226     {
5227       /* Avoid warnings on enum bit fields.  */
5228       if (TREE_CODE (olhstype) == ENUMERAL_TYPE
5229           && TREE_CODE (lhstype) == INTEGER_TYPE)
5230         {
5231           newrhs = convert_for_assignment (olhstype, newrhs, "assignment",
5232                                            NULL_TREE, 0);
5233           newrhs = convert_force (lhstype, newrhs, 0);
5234         }
5235       else
5236         newrhs = convert_for_assignment (lhstype, newrhs, "assignment",
5237                                          NULL_TREE, 0);
5238       if (TREE_CODE (newrhs) == CALL_EXPR
5239           && TYPE_NEEDS_CONSTRUCTING (lhstype))
5240         newrhs = build_cplus_new (lhstype, newrhs);
5241
5242       /* Can't initialize directly from a TARGET_EXPR, since that would
5243          cause the lhs to be constructed twice, and possibly result in
5244          accidental self-initialization.  So we force the TARGET_EXPR to be
5245          expanded without a target.  */
5246       if (TREE_CODE (newrhs) == TARGET_EXPR)
5247         newrhs = build (COMPOUND_EXPR, TREE_TYPE (newrhs), newrhs,
5248                         TREE_OPERAND (newrhs, 0));
5249     }
5250
5251   if (newrhs == error_mark_node)
5252     return error_mark_node;
5253
5254   result = build (modifycode == NOP_EXPR ? MODIFY_EXPR : INIT_EXPR,
5255                   lhstype, lhs, newrhs);
5256
5257   TREE_SIDE_EFFECTS (result) = 1;
5258   if (!plain_assign)
5259     TREE_NO_WARNING (result) = 1;
5260
5261   /* If we got the LHS in a different type for storing in,
5262      convert the result back to the nominal type of LHS
5263      so that the value we return always has the same type
5264      as the LHS argument.  */
5265
5266   if (olhstype == TREE_TYPE (result))
5267     return result;
5268   if (olhs)
5269     {
5270       result = build (COMPOUND_EXPR, olhstype, result, olhs);
5271       TREE_NO_WARNING (result) = 1;
5272       return result;
5273     }
5274   return convert_for_assignment (olhstype, result, "assignment",
5275                                  NULL_TREE, 0);
5276 }
5277
5278 tree
5279 build_x_modify_expr (tree lhs, enum tree_code modifycode, tree rhs)
5280 {
5281   if (processing_template_decl)
5282     return build_min_nt (MODOP_EXPR, lhs,
5283                          build_min_nt (modifycode, NULL_TREE, NULL_TREE), rhs);
5284
5285   if (modifycode != NOP_EXPR)
5286     {
5287       tree rval = build_new_op (MODIFY_EXPR, LOOKUP_NORMAL, lhs, rhs,
5288                                 make_node (modifycode),
5289                                 /*overloaded_p=*/NULL);
5290       if (rval)
5291         {
5292           TREE_NO_WARNING (rval) = 1;
5293           return rval;
5294         }
5295     }
5296   return build_modify_expr (lhs, modifycode, rhs);
5297 }
5298
5299 \f
5300 /* Get difference in deltas for different pointer to member function
5301    types.  Returns an integer constant of type PTRDIFF_TYPE_NODE.  If
5302    the conversion is invalid, the constant is zero.  If FORCE is true,
5303    then allow reverse conversions as well.
5304
5305    Note that the naming of FROM and TO is kind of backwards; the return
5306    value is what we add to a TO in order to get a FROM.  They are named
5307    this way because we call this function to find out how to convert from
5308    a pointer to member of FROM to a pointer to member of TO.  */
5309
5310 static tree
5311 get_delta_difference (tree from, tree to, int force)
5312 {
5313   tree binfo;
5314   tree virt_binfo;
5315   base_kind kind;
5316   tree result;
5317
5318   /* Assume no conversion is required.  */
5319   result = integer_zero_node;
5320   binfo = lookup_base (to, from, ba_check, &kind);
5321   if (kind == bk_inaccessible || kind == bk_ambig)
5322     error ("   in pointer to member function conversion");
5323   else if (!binfo)
5324     {
5325       if (!force)
5326         {
5327           error_not_base_type (from, to);
5328           error ("   in pointer to member conversion");
5329         }
5330       else
5331         {
5332           binfo = lookup_base (from, to, ba_check, &kind);
5333           if (binfo)
5334             {
5335               virt_binfo = binfo_from_vbase (binfo);
5336               if (virt_binfo)
5337                 /* This is a reinterpret cast, we choose to do nothing.  */
5338                 warning ("pointer to member cast via virtual base `%T'",
5339                          BINFO_TYPE (virt_binfo));
5340               else
5341                 result = size_diffop (size_zero_node, BINFO_OFFSET (binfo));
5342             }
5343         }
5344     }
5345   else
5346     {
5347       virt_binfo = binfo_from_vbase (binfo);
5348       if (!virt_binfo)
5349         result = BINFO_OFFSET (binfo);
5350       else
5351         {
5352           /* This is a reinterpret cast, we choose to do nothing.  */
5353           if (force)
5354             warning ("pointer to member cast via virtual base `%T'",
5355                      BINFO_TYPE (virt_binfo));
5356           else
5357             error ("pointer to member conversion via virtual base `%T'",
5358                    BINFO_TYPE (virt_binfo));
5359         }
5360     }
5361
5362   return fold (convert_to_integer (ptrdiff_type_node, result));
5363 }
5364
5365 /* Return a constructor for the pointer-to-member-function TYPE using
5366    the other components as specified.  */
5367
5368 tree
5369 build_ptrmemfunc1 (tree type, tree delta, tree pfn)
5370 {
5371   tree u = NULL_TREE;
5372   tree delta_field;
5373   tree pfn_field;
5374
5375   /* Pull the FIELD_DECLs out of the type.  */
5376   pfn_field = TYPE_FIELDS (type);
5377   delta_field = TREE_CHAIN (pfn_field);
5378
5379   /* Make sure DELTA has the type we want.  */
5380   delta = convert_and_check (delta_type_node, delta);
5381
5382   /* Finish creating the initializer.  */
5383   u = tree_cons (pfn_field, pfn,
5384                  build_tree_list (delta_field, delta));
5385   u = build_constructor (type, u);
5386   TREE_CONSTANT (u) = TREE_CONSTANT (pfn) & TREE_CONSTANT (delta);
5387   TREE_INVARIANT (u) = TREE_INVARIANT (pfn) & TREE_INVARIANT (delta);
5388   TREE_STATIC (u) = (TREE_CONSTANT (u)
5389                      && (initializer_constant_valid_p (pfn, TREE_TYPE (pfn))
5390                          != NULL_TREE)
5391                      && (initializer_constant_valid_p (delta, TREE_TYPE (delta))
5392                          != NULL_TREE));
5393   return u;
5394 }
5395
5396 /* Build a constructor for a pointer to member function.  It can be
5397    used to initialize global variables, local variable, or used
5398    as a value in expressions.  TYPE is the POINTER to METHOD_TYPE we
5399    want to be.
5400
5401    If FORCE is nonzero, then force this conversion, even if
5402    we would rather not do it.  Usually set when using an explicit
5403    cast.
5404
5405    Return error_mark_node, if something goes wrong.  */
5406
5407 tree
5408 build_ptrmemfunc (tree type, tree pfn, int force)
5409 {
5410   tree fn;
5411   tree pfn_type;
5412   tree to_type;
5413
5414   if (error_operand_p (pfn))
5415     return error_mark_node;
5416
5417   pfn_type = TREE_TYPE (pfn);
5418   to_type = build_ptrmemfunc_type (type);
5419
5420   /* Handle multiple conversions of pointer to member functions.  */
5421   if (TYPE_PTRMEMFUNC_P (pfn_type))
5422     {
5423       tree delta = NULL_TREE;
5424       tree npfn = NULL_TREE;
5425       tree n;
5426
5427       if (!force
5428           && !can_convert_arg (to_type, TREE_TYPE (pfn), pfn))
5429         error ("invalid conversion to type `%T' from type `%T'",
5430                   to_type, pfn_type);
5431
5432       n = get_delta_difference (TYPE_PTRMEMFUNC_OBJECT_TYPE (pfn_type),
5433                                 TYPE_PTRMEMFUNC_OBJECT_TYPE (to_type),
5434                                 force);
5435
5436       /* We don't have to do any conversion to convert a
5437          pointer-to-member to its own type.  But, we don't want to
5438          just return a PTRMEM_CST if there's an explicit cast; that
5439          cast should make the expression an invalid template argument.  */
5440       if (TREE_CODE (pfn) != PTRMEM_CST)
5441         {
5442           if (same_type_p (to_type, pfn_type))
5443             return pfn;
5444           else if (integer_zerop (n))
5445             return build_reinterpret_cast (to_type, pfn);
5446         }
5447
5448       if (TREE_SIDE_EFFECTS (pfn))
5449         pfn = save_expr (pfn);
5450
5451       /* Obtain the function pointer and the current DELTA.  */
5452       if (TREE_CODE (pfn) == PTRMEM_CST)
5453         expand_ptrmemfunc_cst (pfn, &delta, &npfn);
5454       else
5455         {
5456           npfn = build_ptrmemfunc_access_expr (pfn, pfn_identifier);
5457           delta = build_ptrmemfunc_access_expr (pfn, delta_identifier);
5458         }
5459
5460       /* Just adjust the DELTA field.  */
5461       my_friendly_assert (TREE_TYPE (delta) == ptrdiff_type_node, 20030727);
5462       if (TARGET_PTRMEMFUNC_VBIT_LOCATION == ptrmemfunc_vbit_in_delta)
5463         n = cp_build_binary_op (LSHIFT_EXPR, n, integer_one_node);
5464       delta = cp_build_binary_op (PLUS_EXPR, delta, n);
5465       return build_ptrmemfunc1 (to_type, delta, npfn);
5466     }
5467
5468   /* Handle null pointer to member function conversions.  */
5469   if (integer_zerop (pfn))
5470     {
5471       pfn = build_c_cast (type, integer_zero_node);
5472       return build_ptrmemfunc1 (to_type,
5473                                 integer_zero_node,
5474                                 pfn);
5475     }
5476
5477   if (type_unknown_p (pfn))
5478     return instantiate_type (type, pfn, tf_error | tf_warning);
5479
5480   fn = TREE_OPERAND (pfn, 0);
5481   my_friendly_assert (TREE_CODE (fn) == FUNCTION_DECL, 0);
5482   return make_ptrmem_cst (to_type, fn);
5483 }
5484
5485 /* Return the DELTA, IDX, PFN, and DELTA2 values for the PTRMEM_CST
5486    given by CST.
5487
5488    ??? There is no consistency as to the types returned for the above
5489    values.  Some code acts as if it were a sizetype and some as if it were
5490    integer_type_node.  */
5491
5492 void
5493 expand_ptrmemfunc_cst (tree cst, tree *delta, tree *pfn)
5494 {
5495   tree type = TREE_TYPE (cst);
5496   tree fn = PTRMEM_CST_MEMBER (cst);
5497   tree ptr_class, fn_class;
5498
5499   my_friendly_assert (TREE_CODE (fn) == FUNCTION_DECL, 0);
5500
5501   /* The class that the function belongs to.  */
5502   fn_class = DECL_CONTEXT (fn);
5503
5504   /* The class that we're creating a pointer to member of.  */
5505   ptr_class = TYPE_PTRMEMFUNC_OBJECT_TYPE (type);
5506
5507   /* First, calculate the adjustment to the function's class.  */
5508   *delta = get_delta_difference (fn_class, ptr_class, /*force=*/0);
5509
5510   if (!DECL_VIRTUAL_P (fn))
5511     *pfn = convert (TYPE_PTRMEMFUNC_FN_TYPE (type), build_addr_func (fn));
5512   else
5513     {
5514       /* If we're dealing with a virtual function, we have to adjust 'this'
5515          again, to point to the base which provides the vtable entry for
5516          fn; the call will do the opposite adjustment.  */
5517       tree orig_class = DECL_CONTEXT (fn);
5518       tree binfo = binfo_or_else (orig_class, fn_class);
5519       *delta = fold (build (PLUS_EXPR, TREE_TYPE (*delta),
5520                             *delta, BINFO_OFFSET (binfo)));
5521
5522       /* We set PFN to the vtable offset at which the function can be
5523          found, plus one (unless ptrmemfunc_vbit_in_delta, in which
5524          case delta is shifted left, and then incremented).  */
5525       *pfn = DECL_VINDEX (fn);
5526       *pfn = fold (build (MULT_EXPR, integer_type_node, *pfn,
5527                           TYPE_SIZE_UNIT (vtable_entry_type)));
5528
5529       switch (TARGET_PTRMEMFUNC_VBIT_LOCATION)
5530         {
5531         case ptrmemfunc_vbit_in_pfn:
5532           *pfn = fold (build (PLUS_EXPR, integer_type_node, *pfn,
5533                               integer_one_node));
5534           break;
5535
5536         case ptrmemfunc_vbit_in_delta:
5537           *delta = fold (build (LSHIFT_EXPR, TREE_TYPE (*delta),
5538                                 *delta, integer_one_node));
5539           *delta = fold (build (PLUS_EXPR, TREE_TYPE (*delta),
5540                                 *delta, integer_one_node));
5541           break;
5542
5543         default:
5544           abort ();
5545         }
5546
5547       *pfn = fold (build1 (NOP_EXPR, TYPE_PTRMEMFUNC_FN_TYPE (type),
5548                            *pfn));
5549     }
5550 }
5551
5552 /* Return an expression for PFN from the pointer-to-member function
5553    given by T.  */
5554
5555 tree
5556 pfn_from_ptrmemfunc (tree t)
5557 {
5558   if (TREE_CODE (t) == PTRMEM_CST)
5559     {
5560       tree delta;
5561       tree pfn;
5562
5563       expand_ptrmemfunc_cst (t, &delta, &pfn);
5564       if (pfn)
5565         return pfn;
5566     }
5567
5568   return build_ptrmemfunc_access_expr (t, pfn_identifier);
5569 }
5570
5571 /* Expression EXPR is about to be implicitly converted to TYPE.  Warn
5572    if this is a potentially dangerous thing to do.  Returns a possibly
5573    marked EXPR.  */
5574
5575 tree
5576 dubious_conversion_warnings (tree type, tree expr,
5577                              const char *errtype, tree fndecl, int parmnum)
5578 {
5579   type = non_reference (type);
5580
5581   /* Issue warnings about peculiar, but valid, uses of NULL.  */
5582   if (ARITHMETIC_TYPE_P (type) && expr == null_node)
5583     {
5584       if (fndecl)
5585         warning ("passing NULL used for non-pointer %s %P of `%D'",
5586                     errtype, parmnum, fndecl);
5587       else
5588         warning ("%s to non-pointer type `%T' from NULL", errtype, type);
5589     }
5590
5591   /* Warn about assigning a floating-point type to an integer type.  */
5592   if (TREE_CODE (TREE_TYPE (expr)) == REAL_TYPE
5593       && TREE_CODE (type) == INTEGER_TYPE)
5594     {
5595       if (fndecl)
5596         warning ("passing `%T' for %s %P of `%D'",
5597                     TREE_TYPE (expr), errtype, parmnum, fndecl);
5598       else
5599         warning ("%s to `%T' from `%T'", errtype, type, TREE_TYPE (expr));
5600     }
5601   /* And warn about assigning a negative value to an unsigned
5602      variable.  */
5603   else if (TYPE_UNSIGNED (type) && TREE_CODE (type) != BOOLEAN_TYPE)
5604     {
5605       if (TREE_CODE (expr) == INTEGER_CST && TREE_NEGATED_INT (expr))
5606         {
5607           if (fndecl)
5608             warning ("passing negative value `%E' for %s %P of `%D'",
5609                         expr, errtype, parmnum, fndecl);
5610           else
5611             warning ("%s of negative value `%E' to `%T'",
5612                         errtype, expr, type);
5613         }
5614
5615       overflow_warning (expr);
5616
5617       if (TREE_CONSTANT (expr))
5618         expr = fold (expr);
5619     }
5620   return expr;
5621 }
5622
5623 /* Convert value RHS to type TYPE as preparation for an assignment to
5624    an lvalue of type TYPE.  ERRTYPE is a string to use in error
5625    messages: "assignment", "return", etc.  If FNDECL is non-NULL, we
5626    are doing the conversion in order to pass the PARMNUMth argument of
5627    FNDECL.  */
5628
5629 static tree
5630 convert_for_assignment (tree type, tree rhs,
5631                         const char *errtype, tree fndecl, int parmnum)
5632 {
5633   tree rhstype;
5634   enum tree_code coder;
5635
5636   /* Strip NON_LVALUE_EXPRs since we aren't using as an lvalue.  */
5637   if (TREE_CODE (rhs) == NON_LVALUE_EXPR)
5638     rhs = TREE_OPERAND (rhs, 0);
5639
5640   rhstype = TREE_TYPE (rhs);
5641   coder = TREE_CODE (rhstype);
5642
5643   if (TREE_CODE (type) == VECTOR_TYPE && coder == VECTOR_TYPE
5644       && vector_types_convertible_p (type, rhstype))
5645     return convert (type, rhs);
5646
5647   if (rhs == error_mark_node || rhstype == error_mark_node)
5648     return error_mark_node;
5649   if (TREE_CODE (rhs) == TREE_LIST && TREE_VALUE (rhs) == error_mark_node)
5650     return error_mark_node;
5651
5652   /* The RHS of an assignment cannot have void type.  */
5653   if (coder == VOID_TYPE)
5654     {
5655       error ("void value not ignored as it ought to be");
5656       return error_mark_node;
5657     }
5658
5659   /* Simplify the RHS if possible.  */
5660   if (TREE_CODE (rhs) == CONST_DECL)
5661     rhs = DECL_INITIAL (rhs);
5662
5663   /* We do not use decl_constant_value here because of this case:
5664
5665        const char* const s = "s";
5666
5667      The conversion rules for a string literal are more lax than for a
5668      variable; in particular, a string literal can be converted to a
5669      "char *" but the variable "s" cannot be converted in the same
5670      way.  If the conversion is allowed, the optimization should be
5671      performed while creating the converted expression.  */
5672
5673   /* [expr.ass]
5674
5675      The expression is implicitly converted (clause _conv_) to the
5676      cv-unqualified type of the left operand.
5677
5678      We allow bad conversions here because by the time we get to this point
5679      we are committed to doing the conversion.  If we end up doing a bad
5680      conversion, convert_like will complain.  */
5681   if (!can_convert_arg_bad (type, rhstype, rhs))
5682     {
5683       /* When -Wno-pmf-conversions is use, we just silently allow
5684          conversions from pointers-to-members to plain pointers.  If
5685          the conversion doesn't work, cp_convert will complain.  */
5686       if (!warn_pmf2ptr
5687           && TYPE_PTR_P (type)
5688           && TYPE_PTRMEMFUNC_P (rhstype))
5689         rhs = cp_convert (strip_top_quals (type), rhs);
5690       else
5691         {
5692           /* If the right-hand side has unknown type, then it is an
5693              overloaded function.  Call instantiate_type to get error
5694              messages.  */
5695           if (rhstype == unknown_type_node)
5696             instantiate_type (type, rhs, tf_error | tf_warning);
5697           else if (fndecl)
5698             error ("cannot convert `%T' to `%T' for argument `%P' to `%D'",
5699                       rhstype, type, parmnum, fndecl);
5700           else
5701             error ("cannot convert `%T' to `%T' in %s", rhstype, type,
5702                       errtype);
5703           return error_mark_node;
5704         }
5705     }
5706   return perform_implicit_conversion (strip_top_quals (type), rhs);
5707 }
5708
5709 /* Convert RHS to be of type TYPE.
5710    If EXP is nonzero, it is the target of the initialization.
5711    ERRTYPE is a string to use in error messages.
5712
5713    Two major differences between the behavior of
5714    `convert_for_assignment' and `convert_for_initialization'
5715    are that references are bashed in the former, while
5716    copied in the latter, and aggregates are assigned in
5717    the former (operator=) while initialized in the
5718    latter (X(X&)).
5719
5720    If using constructor make sure no conversion operator exists, if one does
5721    exist, an ambiguity exists.
5722
5723    If flags doesn't include LOOKUP_COMPLAIN, don't complain about anything.  */
5724
5725 tree
5726 convert_for_initialization (tree exp, tree type, tree rhs, int flags,
5727                             const char *errtype, tree fndecl, int parmnum)
5728 {
5729   enum tree_code codel = TREE_CODE (type);
5730   tree rhstype;
5731   enum tree_code coder;
5732
5733   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
5734      Strip such NOP_EXPRs, since RHS is used in non-lvalue context.  */
5735   if (TREE_CODE (rhs) == NOP_EXPR
5736       && TREE_TYPE (rhs) == TREE_TYPE (TREE_OPERAND (rhs, 0))
5737       && codel != REFERENCE_TYPE)
5738     rhs = TREE_OPERAND (rhs, 0);
5739
5740   if (rhs == error_mark_node
5741       || (TREE_CODE (rhs) == TREE_LIST && TREE_VALUE (rhs) == error_mark_node))
5742     return error_mark_node;
5743
5744   if (TREE_CODE (TREE_TYPE (rhs)) == REFERENCE_TYPE)
5745     rhs = convert_from_reference (rhs);
5746
5747   if ((TREE_CODE (TREE_TYPE (rhs)) == ARRAY_TYPE
5748        && TREE_CODE (type) != ARRAY_TYPE
5749        && (TREE_CODE (type) != REFERENCE_TYPE
5750            || TREE_CODE (TREE_TYPE (type)) != ARRAY_TYPE))
5751       || (TREE_CODE (TREE_TYPE (rhs)) == FUNCTION_TYPE
5752           && (TREE_CODE (type) != REFERENCE_TYPE
5753               || TREE_CODE (TREE_TYPE (type)) != FUNCTION_TYPE))
5754       || TREE_CODE (TREE_TYPE (rhs)) == METHOD_TYPE)
5755     rhs = decay_conversion (rhs);
5756
5757   rhstype = TREE_TYPE (rhs);
5758   coder = TREE_CODE (rhstype);
5759
5760   if (coder == ERROR_MARK)
5761     return error_mark_node;
5762
5763   /* We accept references to incomplete types, so we can
5764      return here before checking if RHS is of complete type.  */
5765
5766   if (codel == REFERENCE_TYPE)
5767     {
5768       /* This should eventually happen in convert_arguments.  */
5769       int savew = 0, savee = 0;
5770
5771       if (fndecl)
5772         savew = warningcount, savee = errorcount;
5773       rhs = initialize_reference (type, rhs, /*decl=*/NULL_TREE,
5774                                   /*cleanup=*/NULL);
5775       if (fndecl)
5776         {
5777           if (warningcount > savew)
5778             cp_warning_at ("in passing argument %P of `%+D'", parmnum, fndecl);
5779           else if (errorcount > savee)
5780             cp_error_at ("in passing argument %P of `%+D'", parmnum, fndecl);
5781         }
5782       return rhs;
5783     }
5784
5785   if (exp != 0)
5786     exp = require_complete_type (exp);
5787   if (exp == error_mark_node)
5788     return error_mark_node;
5789
5790   rhstype = non_reference (rhstype);
5791
5792   type = complete_type (type);
5793
5794   if (IS_AGGR_TYPE (type))
5795     return ocp_convert (type, rhs, CONV_IMPLICIT|CONV_FORCE_TEMP, flags);
5796
5797   return convert_for_assignment (type, rhs, errtype, fndecl, parmnum);
5798 }
5799 \f
5800 /* If RETVAL is the address of, or a reference to, a local variable or
5801    temporary give an appropriate warning.  */
5802
5803 static void
5804 maybe_warn_about_returning_address_of_local (tree retval)
5805 {
5806   tree valtype = TREE_TYPE (DECL_RESULT (current_function_decl));
5807   tree whats_returned = retval;
5808
5809   for (;;)
5810     {
5811       if (TREE_CODE (whats_returned) == COMPOUND_EXPR)
5812         whats_returned = TREE_OPERAND (whats_returned, 1);
5813       else if (TREE_CODE (whats_returned) == CONVERT_EXPR
5814                || TREE_CODE (whats_returned) == NON_LVALUE_EXPR
5815                || TREE_CODE (whats_returned) == NOP_EXPR)
5816         whats_returned = TREE_OPERAND (whats_returned, 0);
5817       else
5818         break;
5819     }
5820
5821   if (TREE_CODE (whats_returned) != ADDR_EXPR)
5822     return;
5823   whats_returned = TREE_OPERAND (whats_returned, 0);
5824
5825   if (TREE_CODE (valtype) == REFERENCE_TYPE)
5826     {
5827       if (TREE_CODE (whats_returned) == AGGR_INIT_EXPR
5828           || TREE_CODE (whats_returned) == TARGET_EXPR)
5829         {
5830           warning ("returning reference to temporary");
5831           return;
5832         }
5833       if (TREE_CODE (whats_returned) == VAR_DECL
5834           && DECL_NAME (whats_returned)
5835           && TEMP_NAME_P (DECL_NAME (whats_returned)))
5836         {
5837           warning ("reference to non-lvalue returned");
5838           return;
5839         }
5840     }
5841
5842   if (DECL_P (whats_returned)
5843       && DECL_NAME (whats_returned)
5844       && DECL_FUNCTION_SCOPE_P (whats_returned)
5845       && !(TREE_STATIC (whats_returned)
5846            || TREE_PUBLIC (whats_returned)))
5847     {
5848       if (TREE_CODE (valtype) == REFERENCE_TYPE)
5849         cp_warning_at ("reference to local variable `%D' returned",
5850                        whats_returned);
5851       else
5852         cp_warning_at ("address of local variable `%D' returned",
5853                        whats_returned);
5854       return;
5855     }
5856 }
5857
5858 /* Check that returning RETVAL from the current function is valid.
5859    Return an expression explicitly showing all conversions required to
5860    change RETVAL into the function return type, and to assign it to
5861    the DECL_RESULT for the function.  */
5862
5863 tree
5864 check_return_expr (tree retval)
5865 {
5866   tree result;
5867   /* The type actually returned by the function, after any
5868      promotions.  */
5869   tree valtype;
5870   int fn_returns_value_p;
5871
5872   /* A `volatile' function is one that isn't supposed to return, ever.
5873      (This is a G++ extension, used to get better code for functions
5874      that call the `volatile' function.)  */
5875   if (TREE_THIS_VOLATILE (current_function_decl))
5876     warning ("function declared `noreturn' has a `return' statement");
5877
5878   /* Check for various simple errors.  */
5879   if (DECL_DESTRUCTOR_P (current_function_decl))
5880     {
5881       if (retval)
5882         error ("returning a value from a destructor");
5883       return NULL_TREE;
5884     }
5885   else if (DECL_CONSTRUCTOR_P (current_function_decl))
5886     {
5887       if (in_function_try_handler)
5888         /* If a return statement appears in a handler of the
5889            function-try-block of a constructor, the program is ill-formed.  */
5890         error ("cannot return from a handler of a function-try-block of a constructor");
5891       else if (retval)
5892         /* You can't return a value from a constructor.  */
5893         error ("returning a value from a constructor");
5894       return NULL_TREE;
5895     }
5896
5897   if (processing_template_decl)
5898     {
5899       current_function_returns_value = 1;
5900       return retval;
5901     }
5902
5903   /* When no explicit return-value is given in a function with a named
5904      return value, the named return value is used.  */
5905   result = DECL_RESULT (current_function_decl);
5906   valtype = TREE_TYPE (result);
5907   my_friendly_assert (valtype != NULL_TREE, 19990924);
5908   fn_returns_value_p = !VOID_TYPE_P (valtype);
5909   if (!retval && DECL_NAME (result) && fn_returns_value_p)
5910     retval = result;
5911
5912   /* Check for a return statement with no return value in a function
5913      that's supposed to return a value.  */
5914   if (!retval && fn_returns_value_p)
5915     {
5916       pedwarn ("return-statement with no value, in function returning '%T'",
5917                valtype);
5918       /* Clear this, so finish_function won't say that we reach the
5919          end of a non-void function (which we don't, we gave a
5920          return!).  */
5921       current_function_returns_null = 0;
5922     }
5923   /* Check for a return statement with a value in a function that
5924      isn't supposed to return a value.  */
5925   else if (retval && !fn_returns_value_p)
5926     {
5927       if (VOID_TYPE_P (TREE_TYPE (retval)))
5928         /* You can return a `void' value from a function of `void'
5929            type.  In that case, we have to evaluate the expression for
5930            its side-effects.  */
5931           finish_expr_stmt (retval);
5932       else
5933         pedwarn ("return-statement with a value, in function "
5934                  "returning 'void'");
5935
5936       current_function_returns_null = 1;
5937
5938       /* There's really no value to return, after all.  */
5939       return NULL_TREE;
5940     }
5941   else if (!retval)
5942     /* Remember that this function can sometimes return without a
5943        value.  */
5944     current_function_returns_null = 1;
5945   else
5946     /* Remember that this function did return a value.  */
5947     current_function_returns_value = 1;
5948
5949   /* Only operator new(...) throw(), can return NULL [expr.new/13].  */
5950   if ((DECL_OVERLOADED_OPERATOR_P (current_function_decl) == NEW_EXPR
5951        || DECL_OVERLOADED_OPERATOR_P (current_function_decl) == VEC_NEW_EXPR)
5952       && !TYPE_NOTHROW_P (TREE_TYPE (current_function_decl))
5953       && ! flag_check_new
5954       && null_ptr_cst_p (retval))
5955     warning ("`operator new' must not return NULL unless it is declared `throw()' (or -fcheck-new is in effect)");
5956
5957   /* Effective C++ rule 15.  See also start_function.  */
5958   if (warn_ecpp
5959       && DECL_NAME (current_function_decl) == ansi_assopname(NOP_EXPR))
5960     {
5961       bool warn = true;
5962
5963       /* The function return type must be a reference to the current
5964         class.  */
5965       if (TREE_CODE (valtype) == REFERENCE_TYPE
5966           && same_type_ignoring_top_level_qualifiers_p
5967               (TREE_TYPE (valtype), TREE_TYPE (current_class_ref)))
5968         {
5969           /* Returning '*this' is obviously OK.  */
5970           if (retval == current_class_ref)
5971             warn = false;
5972           /* If we are calling a function whose return type is the same of
5973              the current class reference, it is ok.  */
5974           else if (TREE_CODE (retval) == INDIRECT_REF
5975                    && TREE_CODE (TREE_OPERAND (retval, 0)) == CALL_EXPR)
5976             warn = false;
5977         }
5978
5979       if (warn)
5980         warning ("`operator=' should return a reference to `*this'");
5981     }
5982
5983   /* The fabled Named Return Value optimization, as per [class.copy]/15:
5984
5985      [...]      For  a function with a class return type, if the expression
5986      in the return statement is the name of a local  object,  and  the  cv-
5987      unqualified  type  of  the  local  object  is the same as the function
5988      return type, an implementation is permitted to omit creating the  tem-
5989      porary  object  to  hold  the function return value [...]
5990
5991      So, if this is a value-returning function that always returns the same
5992      local variable, remember it.
5993
5994      It might be nice to be more flexible, and choose the first suitable
5995      variable even if the function sometimes returns something else, but
5996      then we run the risk of clobbering the variable we chose if the other
5997      returned expression uses the chosen variable somehow.  And people expect
5998      this restriction, anyway.  (jason 2000-11-19)
5999
6000      See finish_function and finalize_nrv for the rest of this optimization.  */
6001
6002   if (fn_returns_value_p && flag_elide_constructors)
6003     {
6004       if (retval != NULL_TREE
6005           && (current_function_return_value == NULL_TREE
6006               || current_function_return_value == retval)
6007           && TREE_CODE (retval) == VAR_DECL
6008           && DECL_CONTEXT (retval) == current_function_decl
6009           && ! TREE_STATIC (retval)
6010           && (DECL_ALIGN (retval)
6011               >= DECL_ALIGN (DECL_RESULT (current_function_decl)))
6012           && same_type_p ((TYPE_MAIN_VARIANT
6013                            (TREE_TYPE (retval))),
6014                           (TYPE_MAIN_VARIANT
6015                            (TREE_TYPE (TREE_TYPE (current_function_decl))))))
6016         current_function_return_value = retval;
6017       else
6018         current_function_return_value = error_mark_node;
6019     }
6020
6021   /* We don't need to do any conversions when there's nothing being
6022      returned.  */
6023   if (!retval || retval == error_mark_node)
6024     return retval;
6025
6026   /* Do any required conversions.  */
6027   if (retval == result || DECL_CONSTRUCTOR_P (current_function_decl))
6028     /* No conversions are required.  */
6029     ;
6030   else
6031     {
6032       /* The type the function is declared to return.  */
6033       tree functype = TREE_TYPE (TREE_TYPE (current_function_decl));
6034
6035       /* First convert the value to the function's return type, then
6036          to the type of return value's location to handle the
6037          case that functype is smaller than the valtype.  */
6038       retval = convert_for_initialization
6039         (NULL_TREE, functype, retval, LOOKUP_NORMAL|LOOKUP_ONLYCONVERTING,
6040          "return", NULL_TREE, 0);
6041       retval = convert (valtype, retval);
6042
6043       /* If the conversion failed, treat this just like `return;'.  */
6044       if (retval == error_mark_node)
6045         return retval;
6046       /* We can't initialize a register from a AGGR_INIT_EXPR.  */
6047       else if (! current_function_returns_struct
6048                && TREE_CODE (retval) == TARGET_EXPR
6049                && TREE_CODE (TREE_OPERAND (retval, 1)) == AGGR_INIT_EXPR)
6050         retval = build (COMPOUND_EXPR, TREE_TYPE (retval), retval,
6051                         TREE_OPERAND (retval, 0));
6052       else
6053         maybe_warn_about_returning_address_of_local (retval);
6054     }
6055
6056   /* Actually copy the value returned into the appropriate location.  */
6057   if (retval && retval != result)
6058     retval = build (INIT_EXPR, TREE_TYPE (result), result, retval);
6059
6060   return retval;
6061 }
6062
6063 \f
6064 /* Returns nonzero if the pointer-type FROM can be converted to the
6065    pointer-type TO via a qualification conversion.  If CONSTP is -1,
6066    then we return nonzero if the pointers are similar, and the
6067    cv-qualification signature of FROM is a proper subset of that of TO.
6068
6069    If CONSTP is positive, then all outer pointers have been
6070    const-qualified.  */
6071
6072 static int
6073 comp_ptr_ttypes_real (tree to, tree from, int constp)
6074 {
6075   bool to_more_cv_qualified = false;
6076
6077   for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
6078     {
6079       if (TREE_CODE (to) != TREE_CODE (from))
6080         return 0;
6081
6082       if (TREE_CODE (from) == OFFSET_TYPE
6083           && !same_type_p (TYPE_OFFSET_BASETYPE (from),
6084                            TYPE_OFFSET_BASETYPE (to)))
6085         return 0;
6086
6087       /* Const and volatile mean something different for function types,
6088          so the usual checks are not appropriate.  */
6089       if (TREE_CODE (to) != FUNCTION_TYPE && TREE_CODE (to) != METHOD_TYPE)
6090         {
6091           if (!at_least_as_qualified_p (to, from))
6092             return 0;
6093
6094           if (!at_least_as_qualified_p (from, to))
6095             {
6096               if (constp == 0)
6097                 return 0;
6098               to_more_cv_qualified = true;
6099             }
6100
6101           if (constp > 0)
6102             constp &= TYPE_READONLY (to);
6103         }
6104
6105       if (TREE_CODE (to) != POINTER_TYPE && !TYPE_PTRMEM_P (to))
6106         return ((constp >= 0 || to_more_cv_qualified)
6107                 && same_type_ignoring_top_level_qualifiers_p (to, from));
6108     }
6109 }
6110
6111 /* When comparing, say, char ** to char const **, this function takes
6112    the 'char *' and 'char const *'.  Do not pass non-pointer/reference
6113    types to this function.  */
6114
6115 int
6116 comp_ptr_ttypes (tree to, tree from)
6117 {
6118   return comp_ptr_ttypes_real (to, from, 1);
6119 }
6120
6121 /* Returns 1 if to and from are (possibly multi-level) pointers to the same
6122    type or inheritance-related types, regardless of cv-quals.  */
6123
6124 int
6125 ptr_reasonably_similar (tree to, tree from)
6126 {
6127   for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
6128     {
6129       /* Any target type is similar enough to void.  */
6130       if (TREE_CODE (to) == VOID_TYPE
6131           || TREE_CODE (from) == VOID_TYPE)
6132         return 1;
6133
6134       if (TREE_CODE (to) != TREE_CODE (from))
6135         return 0;
6136
6137       if (TREE_CODE (from) == OFFSET_TYPE
6138           && comptypes (TYPE_OFFSET_BASETYPE (to),
6139                         TYPE_OFFSET_BASETYPE (from),
6140                         COMPARE_BASE | COMPARE_DERIVED))
6141         continue;
6142
6143       if (TREE_CODE (to) == INTEGER_TYPE
6144           && TYPE_PRECISION (to) == TYPE_PRECISION (from))
6145         return 1;
6146
6147       if (TREE_CODE (to) == FUNCTION_TYPE)
6148         return 1;
6149
6150       if (TREE_CODE (to) != POINTER_TYPE)
6151         return comptypes
6152           (TYPE_MAIN_VARIANT (to), TYPE_MAIN_VARIANT (from),
6153            COMPARE_BASE | COMPARE_DERIVED);
6154     }
6155 }
6156
6157 /* Like comp_ptr_ttypes, for const_cast.  */
6158
6159 static int
6160 comp_ptr_ttypes_const (tree to, tree from)
6161 {
6162   for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
6163     {
6164       if (TREE_CODE (to) != TREE_CODE (from))
6165         return 0;
6166
6167       if (TREE_CODE (from) == OFFSET_TYPE
6168           && same_type_p (TYPE_OFFSET_BASETYPE (from),
6169                           TYPE_OFFSET_BASETYPE (to)))
6170           continue;
6171
6172       if (TREE_CODE (to) != POINTER_TYPE)
6173         return same_type_ignoring_top_level_qualifiers_p (to, from);
6174     }
6175 }
6176
6177 /* Returns the type qualifiers for this type, including the qualifiers on the
6178    elements for an array type.  */
6179
6180 int
6181 cp_type_quals (tree type)
6182 {
6183   type = strip_array_types (type);
6184   if (type == error_mark_node)
6185     return TYPE_UNQUALIFIED;
6186   return TYPE_QUALS (type);
6187 }
6188
6189 /* Returns nonzero if the TYPE contains a mutable member.  */
6190
6191 bool
6192 cp_has_mutable_p (tree type)
6193 {
6194   type = strip_array_types (type);
6195
6196   return CLASS_TYPE_P (type) && CLASSTYPE_HAS_MUTABLE (type);
6197 }
6198
6199 /* Subroutine of casts_away_constness.  Make T1 and T2 point at
6200    exemplar types such that casting T1 to T2 is casting away castness
6201    if and only if there is no implicit conversion from T1 to T2.  */
6202
6203 static void
6204 casts_away_constness_r (tree *t1, tree *t2)
6205 {
6206   int quals1;
6207   int quals2;
6208
6209   /* [expr.const.cast]
6210
6211      For multi-level pointer to members and multi-level mixed pointers
6212      and pointers to members (conv.qual), the "member" aspect of a
6213      pointer to member level is ignored when determining if a const
6214      cv-qualifier has been cast away.  */
6215   if (TYPE_PTRMEM_P (*t1))
6216     *t1 = build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (*t1));
6217   if (TYPE_PTRMEM_P (*t2))
6218     *t2 = build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (*t2));
6219
6220   /* [expr.const.cast]
6221
6222      For  two  pointer types:
6223
6224             X1 is T1cv1,1 * ... cv1,N *   where T1 is not a pointer type
6225             X2 is T2cv2,1 * ... cv2,M *   where T2 is not a pointer type
6226             K is min(N,M)
6227
6228      casting from X1 to X2 casts away constness if, for a non-pointer
6229      type T there does not exist an implicit conversion (clause
6230      _conv_) from:
6231
6232             Tcv1,(N-K+1) * cv1,(N-K+2) * ... cv1,N *
6233
6234      to
6235
6236             Tcv2,(M-K+1) * cv2,(M-K+2) * ... cv2,M *.  */
6237
6238   if (TREE_CODE (*t1) != POINTER_TYPE
6239       || TREE_CODE (*t2) != POINTER_TYPE)
6240     {
6241       *t1 = cp_build_qualified_type (void_type_node,
6242                                      cp_type_quals (*t1));
6243       *t2 = cp_build_qualified_type (void_type_node,
6244                                      cp_type_quals (*t2));
6245       return;
6246     }
6247
6248   quals1 = cp_type_quals (*t1);
6249   quals2 = cp_type_quals (*t2);
6250   *t1 = TREE_TYPE (*t1);
6251   *t2 = TREE_TYPE (*t2);
6252   casts_away_constness_r (t1, t2);
6253   *t1 = build_pointer_type (*t1);
6254   *t2 = build_pointer_type (*t2);
6255   *t1 = cp_build_qualified_type (*t1, quals1);
6256   *t2 = cp_build_qualified_type (*t2, quals2);
6257 }
6258
6259 /* Returns nonzero if casting from TYPE1 to TYPE2 casts away
6260    constness.  */
6261
6262 static bool
6263 casts_away_constness (tree t1, tree t2)
6264 {
6265   if (TREE_CODE (t2) == REFERENCE_TYPE)
6266     {
6267       /* [expr.const.cast]
6268
6269          Casting from an lvalue of type T1 to an lvalue of type T2
6270          using a reference cast casts away constness if a cast from an
6271          rvalue of type "pointer to T1" to the type "pointer to T2"
6272          casts away constness.  */
6273       t1 = (TREE_CODE (t1) == REFERENCE_TYPE ? TREE_TYPE (t1) : t1);
6274       return casts_away_constness (build_pointer_type (t1),
6275                                    build_pointer_type (TREE_TYPE (t2)));
6276     }
6277
6278   if (TYPE_PTRMEM_P (t1) && TYPE_PTRMEM_P (t2))
6279     /* [expr.const.cast]
6280
6281        Casting from an rvalue of type "pointer to data member of X
6282        of type T1" to the type "pointer to data member of Y of type
6283        T2" casts away constness if a cast from an rvalue of type
6284        "pointer to T1" to the type "pointer to T2" casts away
6285        constness.  */
6286     return casts_away_constness
6287       (build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (t1)),
6288        build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (t2)));
6289
6290   /* Casting away constness is only something that makes sense for
6291      pointer or reference types.  */
6292   if (TREE_CODE (t1) != POINTER_TYPE
6293       || TREE_CODE (t2) != POINTER_TYPE)
6294     return false;
6295
6296   /* Top-level qualifiers don't matter.  */
6297   t1 = TYPE_MAIN_VARIANT (t1);
6298   t2 = TYPE_MAIN_VARIANT (t2);
6299   casts_away_constness_r (&t1, &t2);
6300   if (!can_convert (t2, t1))
6301     return true;
6302
6303   return false;
6304 }
6305
6306 /* If T is a REFERENCE_TYPE return the type to which T refers.
6307    Otherwise, return T itself.  */
6308
6309 tree
6310 non_reference (tree t)
6311 {
6312   if (TREE_CODE (t) == REFERENCE_TYPE)
6313     t = TREE_TYPE (t);
6314   return t;
6315 }