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, 2005 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 #include "c-common.h"
  45
  46 static tree convert_for_assignment (tree, tree, const char *, tree, int);
  47 static tree cp_pointer_int_sum (enum tree_code, tree, tree);
  48 static tree rationalize_conditional_expr (enum tree_code, tree);
  49 static int comp_ptr_ttypes_real (tree, tree, int);
  50 static int comp_ptr_ttypes_const (tree, tree);
  51 static bool comp_except_types (tree, tree, bool);
  52 static bool comp_array_types (tree, tree, bool);
  53 static tree common_base_type (tree, tree);
  54 static tree pointer_diff (tree, tree, tree);
  55 static tree get_delta_difference (tree, tree, bool, bool);
  56 static void casts_away_constness_r (tree *, tree *);
  57 static bool casts_away_constness (tree, tree);
  58 static void maybe_warn_about_returning_address_of_local (tree);
  59 static tree lookup_destructor (tree, tree, tree);
  60 static tree convert_arguments (tree, tree, tree, int);
  61
  62 /* Do `exp = require_complete_type (exp);' to make sure exp
  63    does not have an incomplete type.  (That includes void types.)
  64    Returns the error_mark_node if the VALUE does not have
  65    complete type when this function returns.  */
  66
  67 tree
  68 require_complete_type (tree value)
  69 {
  70   tree type;
  71
  72   if (processing_template_decl || value == error_mark_node)
  73     return value;
  74
  75   if (TREE_CODE (value) == OVERLOAD)
  76     type = unknown_type_node;
  77   else
  78     type = TREE_TYPE (value);
  79
  80   if (type == error_mark_node)
  81     return error_mark_node;
  82
  83   /* First, detect a valid value with a complete type.  */
  84   if (COMPLETE_TYPE_P (type))
  85     return value;
  86
  87   if (complete_type_or_else (type, value))
  88     return value;
  89   else
  90     return error_mark_node;
  91 }
  92
  93 /* Try to complete TYPE, if it is incomplete.  For example, if TYPE is
  94    a template instantiation, do the instantiation.  Returns TYPE,
  95    whether or not it could be completed, unless something goes
  96    horribly wrong, in which case the error_mark_node is returned.  */
  97
  98 tree
  99 complete_type (tree type)
 100 {
 101   if (type == NULL_TREE)
 102     /* Rather than crash, we return something sure to cause an error
 103        at some point.  */
 104     return error_mark_node;
 105
 106   if (type == error_mark_node || COMPLETE_TYPE_P (type))
 107     ;
 108   else if (TREE_CODE (type) == ARRAY_TYPE && TYPE_DOMAIN (type))
 109     {
 110       tree t = complete_type (TREE_TYPE (type));
 111       if (COMPLETE_TYPE_P (t) && !dependent_type_p (type))
 112         layout_type (type);
 113       TYPE_NEEDS_CONSTRUCTING (type)
 114         = TYPE_NEEDS_CONSTRUCTING (TYPE_MAIN_VARIANT (t));
 115       TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type)
 116         = TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TYPE_MAIN_VARIANT (t));
 117     }
 118   else if (CLASS_TYPE_P (type) && CLASSTYPE_TEMPLATE_INSTANTIATION (type))
 119     instantiate_class_template (TYPE_MAIN_VARIANT (type));
 120
 121   return type;
 122 }
 123
 124 /* Like complete_type, but issue an error if the TYPE cannot be completed.
 125    VALUE is used for informative diagnostics.
 126    Returns NULL_TREE if the type cannot be made complete.  */
 127
 128 tree
 129 complete_type_or_else (tree type, tree value)
 130 {
 131   type = complete_type (type);
 132   if (type == error_mark_node)
 133     /* We already issued an error.  */
 134     return NULL_TREE;
 135   else if (!COMPLETE_TYPE_P (type))
 136     {
 137       cxx_incomplete_type_diagnostic (value, type, 0);
 138       return NULL_TREE;
 139     }
 140   else
 141     return type;
 142 }
 143
 144 /* Return truthvalue of whether type of EXP is instantiated.  */
 145
 146 int
 147 type_unknown_p (tree exp)
 148 {
 149   return (TREE_CODE (exp) == TREE_LIST
 150           || TREE_TYPE (exp) == unknown_type_node);
 151 }
 152
 153 \f
 154 /* Return the common type of two parameter lists.
 155    We assume that comptypes has already been done and returned 1;
 156    if that isn't so, this may crash.
 157
 158    As an optimization, free the space we allocate if the parameter
 159    lists are already common.  */
 160
 161 static tree
 162 commonparms (tree p1, tree p2)
 163 {
 164   tree oldargs = p1, newargs, n;
 165   int i, len;
 166   int any_change = 0;
 167
 168   len = list_length (p1);
 169   newargs = tree_last (p1);
 170
 171   if (newargs == void_list_node)
 172     i = 1;
 173   else
 174     {
 175       i = 0;
 176       newargs = 0;
 177     }
 178
 179   for (; i < len; i++)
 180     newargs = tree_cons (NULL_TREE, NULL_TREE, newargs);
 181
 182   n = newargs;
 183
 184   for (i = 0; p1;
 185        p1 = TREE_CHAIN (p1), p2 = TREE_CHAIN (p2), n = TREE_CHAIN (n), i++)
 186     {
 187       if (TREE_PURPOSE (p1) && !TREE_PURPOSE (p2))
 188         {
 189           TREE_PURPOSE (n) = TREE_PURPOSE (p1);
 190           any_change = 1;
 191         }
 192       else if (! TREE_PURPOSE (p1))
 193         {
 194           if (TREE_PURPOSE (p2))
 195             {
 196               TREE_PURPOSE (n) = TREE_PURPOSE (p2);
 197               any_change = 1;
 198             }
 199         }
 200       else
 201         {
 202           if (1 != simple_cst_equal (TREE_PURPOSE (p1), TREE_PURPOSE (p2)))
 203             any_change = 1;
 204           TREE_PURPOSE (n) = TREE_PURPOSE (p2);
 205         }
 206       if (TREE_VALUE (p1) != TREE_VALUE (p2))
 207         {
 208           any_change = 1;
 209           TREE_VALUE (n) = merge_types (TREE_VALUE (p1), TREE_VALUE (p2));
 210         }
 211       else
 212         TREE_VALUE (n) = TREE_VALUE (p1);
 213     }
 214   if (! any_change)
 215     return oldargs;
 216
 217   return newargs;
 218 }
 219
 220 /* Given a type, perhaps copied for a typedef,
 221    find the "original" version of it.  */
 222 tree
 223 original_type (tree t)
 224 {
 225   while (TYPE_NAME (t) != NULL_TREE)
 226     {
 227       tree x = TYPE_NAME (t);
 228       if (TREE_CODE (x) != TYPE_DECL)
 229         break;
 230       x = DECL_ORIGINAL_TYPE (x);
 231       if (x == NULL_TREE)
 232         break;
 233       t = x;
 234     }
 235   return t;
 236 }
 237
 238 /* T1 and T2 are arithmetic or enumeration types.  Return the type
 239    that will result from the "usual arithmetic conversions" on T1 and
 240    T2 as described in [expr].  */
 241
 242 tree
 243 type_after_usual_arithmetic_conversions (tree t1, tree t2)
 244 {
 245   enum tree_code code1 = TREE_CODE (t1);
 246   enum tree_code code2 = TREE_CODE (t2);
 247   tree attributes;
 248
 249   /* FIXME: Attributes.  */
 250   gcc_assert (ARITHMETIC_TYPE_P (t1)
 251               || TREE_CODE (t1) == COMPLEX_TYPE
 252               || TREE_CODE (t1) == ENUMERAL_TYPE);
 253   gcc_assert (ARITHMETIC_TYPE_P (t2)
 254               || TREE_CODE (t2) == COMPLEX_TYPE
 255               || TREE_CODE (t2) == ENUMERAL_TYPE);
 256
 257   /* In what follows, we slightly generalize the rules given in [expr] so
 258      as to deal with `long long' and `complex'.  First, merge the
 259      attributes.  */
 260   attributes = (*targetm.merge_type_attributes) (t1, t2);
 261
 262   /* If one type is complex, form the common type of the non-complex
 263      components, then make that complex.  Use T1 or T2 if it is the
 264      required type.  */
 265   if (code1 == COMPLEX_TYPE || code2 == COMPLEX_TYPE)
 266     {
 267       tree subtype1 = code1 == COMPLEX_TYPE ? TREE_TYPE (t1) : t1;
 268       tree subtype2 = code2 == COMPLEX_TYPE ? TREE_TYPE (t2) : t2;
 269       tree subtype
 270         = type_after_usual_arithmetic_conversions (subtype1, subtype2);
 271
 272       if (code1 == COMPLEX_TYPE && TREE_TYPE (t1) == subtype)
 273         return build_type_attribute_variant (t1, attributes);
 274       else if (code2 == COMPLEX_TYPE && TREE_TYPE (t2) == subtype)
 275         return build_type_attribute_variant (t2, attributes);
 276       else
 277         return build_type_attribute_variant (build_complex_type (subtype),
 278                                              attributes);
 279     }
 280
 281   /* If only one is real, use it as the result.  */
 282   if (code1 == REAL_TYPE && code2 != REAL_TYPE)
 283     return build_type_attribute_variant (t1, attributes);
 284   if (code2 == REAL_TYPE && code1 != REAL_TYPE)
 285     return build_type_attribute_variant (t2, attributes);
 286
 287   /* Perform the integral promotions.  */
 288   if (code1 != REAL_TYPE)
 289     {
 290       t1 = type_promotes_to (t1);
 291       t2 = type_promotes_to (t2);
 292     }
 293
 294   /* Both real or both integers; use the one with greater precision.  */
 295   if (TYPE_PRECISION (t1) > TYPE_PRECISION (t2))
 296     return build_type_attribute_variant (t1, attributes);
 297   else if (TYPE_PRECISION (t2) > TYPE_PRECISION (t1))
 298     return build_type_attribute_variant (t2, attributes);
 299
 300   /* The types are the same; no need to do anything fancy.  */
 301   if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
 302     return build_type_attribute_variant (t1, attributes);
 303
 304   if (code1 != REAL_TYPE)
 305     {
 306       /* If one is a sizetype, use it so size_binop doesn't blow up.  */
 307       if (TYPE_IS_SIZETYPE (t1) > TYPE_IS_SIZETYPE (t2))
 308         return build_type_attribute_variant (t1, attributes);
 309       if (TYPE_IS_SIZETYPE (t2) > TYPE_IS_SIZETYPE (t1))
 310         return build_type_attribute_variant (t2, attributes);
 311
 312       /* If one is unsigned long long, then convert the other to unsigned
 313          long long.  */
 314       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_long_unsigned_type_node)
 315           || same_type_p (TYPE_MAIN_VARIANT (t2), long_long_unsigned_type_node))
 316         return build_type_attribute_variant (long_long_unsigned_type_node,
 317                                              attributes);
 318       /* If one is a long long, and the other is an unsigned long, and
 319          long long can represent all the values of an unsigned long, then
 320          convert to a long long.  Otherwise, convert to an unsigned long
 321          long.  Otherwise, if either operand is long long, convert the
 322          other to long long.
 323
 324          Since we're here, we know the TYPE_PRECISION is the same;
 325          therefore converting to long long cannot represent all the values
 326          of an unsigned long, so we choose unsigned long long in that
 327          case.  */
 328       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_long_integer_type_node)
 329           || same_type_p (TYPE_MAIN_VARIANT (t2), long_long_integer_type_node))
 330         {
 331           tree t = ((TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 332                     ? long_long_unsigned_type_node
 333                     : long_long_integer_type_node);
 334           return build_type_attribute_variant (t, attributes);
 335         }
 336
 337       /* Go through the same procedure, but for longs.  */
 338       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_unsigned_type_node)
 339           || same_type_p (TYPE_MAIN_VARIANT (t2), long_unsigned_type_node))
 340         return build_type_attribute_variant (long_unsigned_type_node,
 341                                              attributes);
 342       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_integer_type_node)
 343           || same_type_p (TYPE_MAIN_VARIANT (t2), long_integer_type_node))
 344         {
 345           tree t = ((TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 346                     ? long_unsigned_type_node : long_integer_type_node);
 347           return build_type_attribute_variant (t, attributes);
 348         }
 349       /* Otherwise prefer the unsigned one.  */
 350       if (TYPE_UNSIGNED (t1))
 351         return build_type_attribute_variant (t1, attributes);
 352       else
 353         return build_type_attribute_variant (t2, attributes);
 354     }
 355   else
 356     {
 357       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_double_type_node)
 358           || same_type_p (TYPE_MAIN_VARIANT (t2), long_double_type_node))
 359         return build_type_attribute_variant (long_double_type_node,
 360                                              attributes);
 361       if (same_type_p (TYPE_MAIN_VARIANT (t1), double_type_node)
 362           || same_type_p (TYPE_MAIN_VARIANT (t2), double_type_node))
 363         return build_type_attribute_variant (double_type_node,
 364                                              attributes);
 365       if (same_type_p (TYPE_MAIN_VARIANT (t1), float_type_node)
 366           || same_type_p (TYPE_MAIN_VARIANT (t2), float_type_node))
 367         return build_type_attribute_variant (float_type_node,
 368                                              attributes);
 369
 370       /* Two floating-point types whose TYPE_MAIN_VARIANTs are none of
 371          the standard C++ floating-point types.  Logic earlier in this
 372          function has already eliminated the possibility that
 373          TYPE_PRECISION (t2) != TYPE_PRECISION (t1), so there's no
 374          compelling reason to choose one or the other.  */
 375       return build_type_attribute_variant (t1, attributes);
 376     }
 377 }
 378
 379 /* Subroutine of composite_pointer_type to implement the recursive
 380    case.  See that function for documentation fo the parameters.  */
 381
 382 static tree
 383 composite_pointer_type_r (tree t1, tree t2, const char* location)
 384 {
 385   tree pointee1;
 386   tree pointee2;
 387   tree result_type;
 388   tree attributes;
 389
 390   /* Determine the types pointed to by T1 and T2.  */
 391   if (TREE_CODE (t1) == POINTER_TYPE)
 392     {
 393       pointee1 = TREE_TYPE (t1);
 394       pointee2 = TREE_TYPE (t2);
 395     }
 396   else
 397     {
 398       pointee1 = TYPE_PTRMEM_POINTED_TO_TYPE (t1);
 399       pointee2 = TYPE_PTRMEM_POINTED_TO_TYPE (t2);
 400     }
 401
 402   /* [expr.rel]
 403
 404      Otherwise, the composite pointer type is a pointer type
 405      similar (_conv.qual_) to the type of one of the operands,
 406      with a cv-qualification signature (_conv.qual_) that is the
 407      union of the cv-qualification signatures of the operand
 408      types.  */
 409   if (same_type_ignoring_top_level_qualifiers_p (pointee1, pointee2))
 410     result_type = pointee1;
 411   else if ((TREE_CODE (pointee1) == POINTER_TYPE
 412             && TREE_CODE (pointee2) == POINTER_TYPE)
 413            || (TYPE_PTR_TO_MEMBER_P (pointee1)
 414                && TYPE_PTR_TO_MEMBER_P (pointee2)))
 415     result_type = composite_pointer_type_r (pointee1, pointee2, location);
 416   else
 417     {
 418       pedwarn ("%s between distinct pointer types %qT and %qT "
 419                "lacks a cast",
 420                location, t1, t2);
 421       result_type = void_type_node;
 422     }
 423   result_type = cp_build_qualified_type (result_type,
 424                                          (cp_type_quals (pointee1)
 425                                           | cp_type_quals (pointee2)));
 426   /* If the original types were pointers to members, so is the
 427      result.  */
 428   if (TYPE_PTR_TO_MEMBER_P (t1))
 429     {
 430       if (!same_type_p (TYPE_PTRMEM_CLASS_TYPE (t1),
 431                         TYPE_PTRMEM_CLASS_TYPE (t2)))
 432         pedwarn ("%s between distinct pointer types %qT and %qT "
 433                  "lacks a cast",
 434                  location, t1, t2);
 435       result_type = build_ptrmem_type (TYPE_PTRMEM_CLASS_TYPE (t1),
 436                                        result_type);
 437     }
 438   else
 439     result_type = build_pointer_type (result_type);
 440
 441   /* Merge the attributes.  */
 442   attributes = (*targetm.merge_type_attributes) (t1, t2);
 443   return build_type_attribute_variant (result_type, attributes);
 444 }
 445
 446 /* Return the composite pointer type (see [expr.rel]) for T1 and T2.
 447    ARG1 and ARG2 are the values with those types.  The LOCATION is a
 448    string describing the current location, in case an error occurs.
 449
 450    This routine also implements the computation of a common type for
 451    pointers-to-members as per [expr.eq].  */
 452
 453 tree
 454 composite_pointer_type (tree t1, tree t2, tree arg1, tree arg2,
 455                         const char* location)
 456 {
 457   tree class1;
 458   tree class2;
 459
 460   /* [expr.rel]
 461
 462      If one operand is a null pointer constant, the composite pointer
 463      type is the type of the other operand.  */
 464   if (null_ptr_cst_p (arg1))
 465     return t2;
 466   if (null_ptr_cst_p (arg2))
 467     return t1;
 468
 469   /* We have:
 470
 471        [expr.rel]
 472
 473        If one of the operands has type "pointer to cv1 void*", then
 474        the other has type "pointer to cv2T", and the composite pointer
 475        type is "pointer to cv12 void", where cv12 is the union of cv1
 476        and cv2.
 477
 478     If either type is a pointer to void, make sure it is T1.  */
 479   if (TREE_CODE (t2) == POINTER_TYPE && VOID_TYPE_P (TREE_TYPE (t2)))
 480     {
 481       tree t;
 482       t = t1;
 483       t1 = t2;
 484       t2 = t;
 485     }
 486
 487   /* Now, if T1 is a pointer to void, merge the qualifiers.  */
 488   if (TREE_CODE (t1) == POINTER_TYPE && VOID_TYPE_P (TREE_TYPE (t1)))
 489     {
 490       tree attributes;
 491       tree result_type;
 492
 493       if (pedantic && TYPE_PTRFN_P (t2))
 494         pedwarn ("ISO C++ forbids %s between pointer of type %<void *%> "
 495                  "and pointer-to-function", location);
 496       result_type
 497         = cp_build_qualified_type (void_type_node,
 498                                    (cp_type_quals (TREE_TYPE (t1))
 499                                     | cp_type_quals (TREE_TYPE (t2))));
 500       result_type = build_pointer_type (result_type);
 501       /* Merge the attributes.  */
 502       attributes = (*targetm.merge_type_attributes) (t1, t2);
 503       return build_type_attribute_variant (result_type, attributes);
 504     }
 505
 506   /* [expr.eq] permits the application of a pointer conversion to
 507      bring the pointers to a common type.  */
 508   if (TREE_CODE (t1) == POINTER_TYPE && TREE_CODE (t2) == POINTER_TYPE
 509       && CLASS_TYPE_P (TREE_TYPE (t1))
 510       && CLASS_TYPE_P (TREE_TYPE (t2))
 511       && !same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (t1),
 512                                                      TREE_TYPE (t2)))
 513     {
 514       class1 = TREE_TYPE (t1);
 515       class2 = TREE_TYPE (t2);
 516
 517       if (DERIVED_FROM_P (class1, class2))
 518         t2 = (build_pointer_type
 519               (cp_build_qualified_type (class1, TYPE_QUALS (class2))));
 520       else if (DERIVED_FROM_P (class2, class1))
 521         t1 = (build_pointer_type
 522               (cp_build_qualified_type (class2, TYPE_QUALS (class1))));
 523       else
 524         {
 525           error ("%s between distinct pointer types %qT and %qT "
 526                  "lacks a cast", location, t1, t2);
 527           return error_mark_node;
 528         }
 529     }
 530   /* [expr.eq] permits the application of a pointer-to-member
 531      conversion to change the class type of one of the types.  */
 532   else if (TYPE_PTR_TO_MEMBER_P (t1)
 533            && !same_type_p (TYPE_PTRMEM_CLASS_TYPE (t1),
 534                             TYPE_PTRMEM_CLASS_TYPE (t2)))
 535     {
 536       class1 = TYPE_PTRMEM_CLASS_TYPE (t1);
 537       class2 = TYPE_PTRMEM_CLASS_TYPE (t2);
 538
 539       if (DERIVED_FROM_P (class1, class2))
 540         t1 = build_ptrmem_type (class2, TYPE_PTRMEM_POINTED_TO_TYPE (t1));
 541       else if (DERIVED_FROM_P (class2, class1))
 542         t2 = build_ptrmem_type (class1, TYPE_PTRMEM_POINTED_TO_TYPE (t2));
 543       else
 544         {
 545           error ("%s between distinct pointer-to-member types %qT and %qT "
 546                  "lacks a cast", location, t1, t2);
 547           return error_mark_node;
 548         }
 549     }
 550
 551   return composite_pointer_type_r (t1, t2, location);
 552 }
 553
 554 /* Return the merged type of two types.
 555    We assume that comptypes has already been done and returned 1;
 556    if that isn't so, this may crash.
 557
 558    This just combines attributes and default arguments; any other
 559    differences would cause the two types to compare unalike.  */
 560
 561 tree
 562 merge_types (tree t1, tree t2)
 563 {
 564   enum tree_code code1;
 565   enum tree_code code2;
 566   tree attributes;
 567
 568   /* Save time if the two types are the same.  */
 569   if (t1 == t2)
 570     return t1;
 571   if (original_type (t1) == original_type (t2))
 572     return t1;
 573
 574   /* If one type is nonsense, use the other.  */
 575   if (t1 == error_mark_node)
 576     return t2;
 577   if (t2 == error_mark_node)
 578     return t1;
 579
 580   /* Merge the attributes.  */
 581   attributes = (*targetm.merge_type_attributes) (t1, t2);
 582
 583   if (TYPE_PTRMEMFUNC_P (t1))
 584     t1 = TYPE_PTRMEMFUNC_FN_TYPE (t1);
 585   if (TYPE_PTRMEMFUNC_P (t2))
 586     t2 = TYPE_PTRMEMFUNC_FN_TYPE (t2);
 587
 588   code1 = TREE_CODE (t1);
 589   code2 = TREE_CODE (t2);
 590
 591   switch (code1)
 592     {
 593     case POINTER_TYPE:
 594     case REFERENCE_TYPE:
 595       /* For two pointers, do this recursively on the target type.  */
 596       {
 597         tree target = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
 598         int quals = cp_type_quals (t1);
 599
 600         if (code1 == POINTER_TYPE)
 601           t1 = build_pointer_type (target);
 602         else
 603           t1 = build_reference_type (target);
 604         t1 = build_type_attribute_variant (t1, attributes);
 605         t1 = cp_build_qualified_type (t1, quals);
 606
 607         if (TREE_CODE (target) == METHOD_TYPE)
 608           t1 = build_ptrmemfunc_type (t1);
 609
 610         return t1;
 611       }
 612
 613     case OFFSET_TYPE:
 614       {
 615         int quals;
 616         tree pointee;
 617         quals = cp_type_quals (t1);
 618         pointee = merge_types (TYPE_PTRMEM_POINTED_TO_TYPE (t1),
 619                                TYPE_PTRMEM_POINTED_TO_TYPE (t2));
 620         t1 = build_ptrmem_type (TYPE_PTRMEM_CLASS_TYPE (t1),
 621                                 pointee);
 622         t1 = cp_build_qualified_type (t1, quals);
 623         break;
 624       }
 625
 626     case ARRAY_TYPE:
 627       {
 628         tree elt = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
 629         /* Save space: see if the result is identical to one of the args.  */
 630         if (elt == TREE_TYPE (t1) && TYPE_DOMAIN (t1))
 631           return build_type_attribute_variant (t1, attributes);
 632         if (elt == TREE_TYPE (t2) && TYPE_DOMAIN (t2))
 633           return build_type_attribute_variant (t2, attributes);
 634         /* Merge the element types, and have a size if either arg has one.  */
 635         t1 = build_cplus_array_type
 636           (elt, TYPE_DOMAIN (TYPE_DOMAIN (t1) ? t1 : t2));
 637         break;
 638       }
 639
 640     case FUNCTION_TYPE:
 641       /* Function types: prefer the one that specified arg types.
 642          If both do, merge the arg types.  Also merge the return types.  */
 643       {
 644         tree valtype = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
 645         tree p1 = TYPE_ARG_TYPES (t1);
 646         tree p2 = TYPE_ARG_TYPES (t2);
 647         tree rval, raises;
 648
 649         /* Save space: see if the result is identical to one of the args.  */
 650         if (valtype == TREE_TYPE (t1) && ! p2)
 651           return cp_build_type_attribute_variant (t1, attributes);
 652         if (valtype == TREE_TYPE (t2) && ! p1)
 653           return cp_build_type_attribute_variant (t2, attributes);
 654
 655         /* Simple way if one arg fails to specify argument types.  */
 656         if (p1 == NULL_TREE || TREE_VALUE (p1) == void_type_node)
 657           {
 658             rval = build_function_type (valtype, p2);
 659             if ((raises = TYPE_RAISES_EXCEPTIONS (t2)))
 660               rval = build_exception_variant (rval, raises);
 661             return cp_build_type_attribute_variant (rval, attributes);
 662           }
 663         raises = TYPE_RAISES_EXCEPTIONS (t1);
 664         if (p2 == NULL_TREE || TREE_VALUE (p2) == void_type_node)
 665           {
 666             rval = build_function_type (valtype, p1);
 667             if (raises)
 668               rval = build_exception_variant (rval, raises);
 669             return cp_build_type_attribute_variant (rval, attributes);
 670           }
 671
 672         rval = build_function_type (valtype, commonparms (p1, p2));
 673         t1 = build_exception_variant (rval, raises);
 674         break;
 675       }
 676
 677     case METHOD_TYPE:
 678       {
 679         /* Get this value the long way, since TYPE_METHOD_BASETYPE
 680            is just the main variant of this.  */
 681         tree basetype = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (t2)));
 682         tree raises = TYPE_RAISES_EXCEPTIONS (t1);
 683         tree t3;
 684
 685         /* If this was a member function type, get back to the
 686            original type of type member function (i.e., without
 687            the class instance variable up front.  */
 688         t1 = build_function_type (TREE_TYPE (t1),
 689                                   TREE_CHAIN (TYPE_ARG_TYPES (t1)));
 690         t2 = build_function_type (TREE_TYPE (t2),
 691                                   TREE_CHAIN (TYPE_ARG_TYPES (t2)));
 692         t3 = merge_types (t1, t2);
 693         t3 = build_method_type_directly (basetype, TREE_TYPE (t3),
 694                                          TYPE_ARG_TYPES (t3));
 695         t1 = build_exception_variant (t3, raises);
 696         break;
 697       }
 698
 699     case TYPENAME_TYPE:
 700       /* There is no need to merge attributes into a TYPENAME_TYPE.
 701          When the type is instantiated it will have whatever
 702          attributes result from the instantiation.  */
 703       return t1;
 704
 705     default:;
 706     }
 707   return cp_build_type_attribute_variant (t1, attributes);
 708 }
 709
 710 /* Return the common type of two types.
 711    We assume that comptypes has already been done and returned 1;
 712    if that isn't so, this may crash.
 713
 714    This is the type for the result of most arithmetic operations
 715    if the operands have the given two types.  */
 716
 717 tree
 718 common_type (tree t1, tree t2)
 719 {
 720   enum tree_code code1;
 721   enum tree_code code2;
 722
 723   /* If one type is nonsense, bail.  */
 724   if (t1 == error_mark_node || t2 == error_mark_node)
 725     return error_mark_node;
 726
 727   code1 = TREE_CODE (t1);
 728   code2 = TREE_CODE (t2);
 729
 730   if ((ARITHMETIC_TYPE_P (t1) || code1 == ENUMERAL_TYPE
 731        || code1 == COMPLEX_TYPE)
 732       && (ARITHMETIC_TYPE_P (t2) || code2 == ENUMERAL_TYPE
 733           || code2 == COMPLEX_TYPE))
 734     return type_after_usual_arithmetic_conversions (t1, t2);
 735
 736   else if ((TYPE_PTR_P (t1) && TYPE_PTR_P (t2))
 737            || (TYPE_PTRMEM_P (t1) && TYPE_PTRMEM_P (t2))
 738            || (TYPE_PTRMEMFUNC_P (t1) && TYPE_PTRMEMFUNC_P (t2)))
 739     return composite_pointer_type (t1, t2, error_mark_node, error_mark_node,
 740                                    "conversion");
 741   else
 742     gcc_unreachable ();
 743 }
 744 \f
 745 /* Compare two exception specifier types for exactness or subsetness, if
 746    allowed. Returns false for mismatch, true for match (same, or
 747    derived and !exact).
 748
 749    [except.spec] "If a class X ... objects of class X or any class publicly
 750    and unambiguously derived from X. Similarly, if a pointer type Y * ...
 751    exceptions of type Y * or that are pointers to any type publicly and
 752    unambiguously derived from Y. Otherwise a function only allows exceptions
 753    that have the same type ..."
 754    This does not mention cv qualifiers and is different to what throw
 755    [except.throw] and catch [except.catch] will do. They will ignore the
 756    top level cv qualifiers, and allow qualifiers in the pointer to class
 757    example.
 758
 759    We implement the letter of the standard.  */
 760
 761 static bool
 762 comp_except_types (tree a, tree b, bool exact)
 763 {
 764   if (same_type_p (a, b))
 765     return true;
 766   else if (!exact)
 767     {
 768       if (cp_type_quals (a) || cp_type_quals (b))
 769         return false;
 770
 771       if (TREE_CODE (a) == POINTER_TYPE
 772           && TREE_CODE (b) == POINTER_TYPE)
 773         {
 774           a = TREE_TYPE (a);
 775           b = TREE_TYPE (b);
 776           if (cp_type_quals (a) || cp_type_quals (b))
 777             return false;
 778         }
 779
 780       if (TREE_CODE (a) != RECORD_TYPE
 781           || TREE_CODE (b) != RECORD_TYPE)
 782         return false;
 783
 784       if (PUBLICLY_UNIQUELY_DERIVED_P (a, b))
 785         return true;
 786     }
 787   return false;
 788 }
 789
 790 /* Return true if TYPE1 and TYPE2 are equivalent exception specifiers.
 791    If EXACT is false, T2 can be stricter than T1 (according to 15.4/7),
 792    otherwise it must be exact. Exception lists are unordered, but
 793    we've already filtered out duplicates. Most lists will be in order,
 794    we should try to make use of that.  */
 795
 796 bool
 797 comp_except_specs (tree t1, tree t2, bool exact)
 798 {
 799   tree probe;
 800   tree base;
 801   int  length = 0;
 802
 803   if (t1 == t2)
 804     return true;
 805
 806   if (t1 == NULL_TREE)              /* T1 is ...  */
 807     return t2 == NULL_TREE || !exact;
 808   if (!TREE_VALUE (t1)) /* t1 is EMPTY */
 809     return t2 != NULL_TREE && !TREE_VALUE (t2);
 810   if (t2 == NULL_TREE)              /* T2 is ...  */
 811     return false;
 812   if (TREE_VALUE (t1) && !TREE_VALUE (t2)) /* T2 is EMPTY, T1 is not */
 813     return !exact;
 814
 815   /* Neither set is ... or EMPTY, make sure each part of T2 is in T1.
 816      Count how many we find, to determine exactness. For exact matching and
 817      ordered T1, T2, this is an O(n) operation, otherwise its worst case is
 818      O(nm).  */
 819   for (base = t1; t2 != NULL_TREE; t2 = TREE_CHAIN (t2))
 820     {
 821       for (probe = base; probe != NULL_TREE; probe = TREE_CHAIN (probe))
 822         {
 823           tree a = TREE_VALUE (probe);
 824           tree b = TREE_VALUE (t2);
 825
 826           if (comp_except_types (a, b, exact))
 827             {
 828               if (probe == base && exact)
 829                 base = TREE_CHAIN (probe);
 830               length++;
 831               break;
 832             }
 833         }
 834       if (probe == NULL_TREE)
 835         return false;
 836     }
 837   return !exact || base == NULL_TREE || length == list_length (t1);
 838 }
 839
 840 /* Compare the array types T1 and T2.  ALLOW_REDECLARATION is true if
 841    [] can match [size].  */
 842
 843 static bool
 844 comp_array_types (tree t1, tree t2, bool allow_redeclaration)
 845 {
 846   tree d1;
 847   tree d2;
 848   tree max1, max2;
 849
 850   if (t1 == t2)
 851     return true;
 852
 853   /* The type of the array elements must be the same.  */
 854   if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
 855     return false;
 856
 857   d1 = TYPE_DOMAIN (t1);
 858   d2 = TYPE_DOMAIN (t2);
 859
 860   if (d1 == d2)
 861     return true;
 862
 863   /* If one of the arrays is dimensionless, and the other has a
 864      dimension, they are of different types.  However, it is valid to
 865      write:
 866
 867        extern int a[];
 868        int a[3];
 869
 870      by [basic.link]:
 871
 872        declarations for an array object can specify
 873        array types that differ by the presence or absence of a major
 874        array bound (_dcl.array_).  */
 875   if (!d1 || !d2)
 876     return allow_redeclaration;
 877
 878   /* Check that the dimensions are the same.  */
 879
 880   if (!cp_tree_equal (TYPE_MIN_VALUE (d1), TYPE_MIN_VALUE (d2)))
 881     return false;
 882   max1 = TYPE_MAX_VALUE (d1);
 883   max2 = TYPE_MAX_VALUE (d2);
 884   if (processing_template_decl && !abi_version_at_least (2)
 885       && !value_dependent_expression_p (max1)
 886       && !value_dependent_expression_p (max2))
 887     {
 888       /* With abi-1 we do not fold non-dependent array bounds, (and
 889          consequently mangle them incorrectly).  We must therefore
 890          fold them here, to verify the domains have the same
 891          value.  */
 892       max1 = fold (max1);
 893       max2 = fold (max2);
 894     }
 895
 896   if (!cp_tree_equal (max1, max2))
 897     return false;
 898
 899   return true;
 900 }
 901
 902 /* Return true if T1 and T2 are related as allowed by STRICT.  STRICT
 903    is a bitwise-or of the COMPARE_* flags.  */
 904
 905 bool
 906 comptypes (tree t1, tree t2, int strict)
 907 {
 908   if (t1 == t2)
 909     return true;
 910
 911   /* Suppress errors caused by previously reported errors.  */
 912   if (t1 == error_mark_node || t2 == error_mark_node)
 913     return false;
 914
 915   gcc_assert (TYPE_P (t1) && TYPE_P (t2));
 916
 917   /* TYPENAME_TYPEs should be resolved if the qualifying scope is the
 918      current instantiation.  */
 919   if (TREE_CODE (t1) == TYPENAME_TYPE)
 920     {
 921       tree resolved = resolve_typename_type (t1, /*only_current_p=*/true);
 922
 923       if (resolved != error_mark_node)
 924         t1 = resolved;
 925     }
 926
 927   if (TREE_CODE (t2) == TYPENAME_TYPE)
 928     {
 929       tree resolved = resolve_typename_type (t2, /*only_current_p=*/true);
 930
 931       if (resolved != error_mark_node)
 932         t2 = resolved;
 933     }
 934
 935   /* If either type is the internal version of sizetype, use the
 936      language version.  */
 937   if (TREE_CODE (t1) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t1)
 938       && TYPE_ORIG_SIZE_TYPE (t1))
 939     t1 = TYPE_ORIG_SIZE_TYPE (t1);
 940
 941   if (TREE_CODE (t2) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t2)
 942       && TYPE_ORIG_SIZE_TYPE (t2))
 943     t2 = TYPE_ORIG_SIZE_TYPE (t2);
 944
 945   if (TYPE_PTRMEMFUNC_P (t1))
 946     t1 = TYPE_PTRMEMFUNC_FN_TYPE (t1);
 947   if (TYPE_PTRMEMFUNC_P (t2))
 948     t2 = TYPE_PTRMEMFUNC_FN_TYPE (t2);
 949
 950   /* Different classes of types can't be compatible.  */
 951   if (TREE_CODE (t1) != TREE_CODE (t2))
 952     return false;
 953
 954   /* Qualifiers must match.  For array types, we will check when we
 955      recur on the array element types.  */
 956   if (TREE_CODE (t1) != ARRAY_TYPE
 957       && TYPE_QUALS (t1) != TYPE_QUALS (t2))
 958     return false;
 959   if (TYPE_FOR_JAVA (t1) != TYPE_FOR_JAVA (t2))
 960     return false;
 961
 962   /* Allow for two different type nodes which have essentially the same
 963      definition.  Note that we already checked for equality of the type
 964      qualifiers (just above).  */
 965
 966   if (TREE_CODE (t1) != ARRAY_TYPE
 967       && TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
 968     return true;
 969
 970   /* Compare the types.  Break out if they could be the same.  */
 971   switch (TREE_CODE (t1))
 972     {
 973     case TEMPLATE_TEMPLATE_PARM:
 974     case BOUND_TEMPLATE_TEMPLATE_PARM:
 975       if (TEMPLATE_TYPE_IDX (t1) != TEMPLATE_TYPE_IDX (t2)
 976           || TEMPLATE_TYPE_LEVEL (t1) != TEMPLATE_TYPE_LEVEL (t2))
 977         return false;
 978       if (!comp_template_parms
 979           (DECL_TEMPLATE_PARMS (TEMPLATE_TEMPLATE_PARM_TEMPLATE_DECL (t1)),
 980            DECL_TEMPLATE_PARMS (TEMPLATE_TEMPLATE_PARM_TEMPLATE_DECL (t2))))
 981         return false;
 982       if (TREE_CODE (t1) == TEMPLATE_TEMPLATE_PARM)
 983         break;
 984       /* Don't check inheritance.  */
 985       strict = COMPARE_STRICT;
 986       /* Fall through.  */
 987
 988     case RECORD_TYPE:
 989     case UNION_TYPE:
 990       if (TYPE_TEMPLATE_INFO (t1) && TYPE_TEMPLATE_INFO (t2)
 991           && (TYPE_TI_TEMPLATE (t1) == TYPE_TI_TEMPLATE (t2)
 992               || TREE_CODE (t1) == BOUND_TEMPLATE_TEMPLATE_PARM)
 993           && comp_template_args (TYPE_TI_ARGS (t1), TYPE_TI_ARGS (t2)))
 994         break;
 995
 996       if ((strict & COMPARE_BASE) && DERIVED_FROM_P (t1, t2))
 997         break;
 998       else if ((strict & COMPARE_DERIVED) && DERIVED_FROM_P (t2, t1))
 999         break;
1000
1001       /* We may be dealing with Objective-C instances.  */
1002       if (TREE_CODE (t1) == RECORD_TYPE
1003           && objc_comptypes (t1, t2, 0) > 0)
1004         break;
1005
1006       return false;
1007
1008     case OFFSET_TYPE:
1009       if (!comptypes (TYPE_OFFSET_BASETYPE (t1), TYPE_OFFSET_BASETYPE (t2),
1010                       strict & ~COMPARE_REDECLARATION))
1011         return false;
1012       if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
1013         return false;
1014       break;
1015
1016     case POINTER_TYPE:
1017     case REFERENCE_TYPE:
1018       if (TYPE_MODE (t1) != TYPE_MODE (t2)
1019           || TYPE_REF_CAN_ALIAS_ALL (t1) != TYPE_REF_CAN_ALIAS_ALL (t2)
1020           || !same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
1021         return false;
1022       break;
1023
1024     case METHOD_TYPE:
1025     case FUNCTION_TYPE:
1026       if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
1027         return false;
1028       if (!compparms (TYPE_ARG_TYPES (t1), TYPE_ARG_TYPES (t2)))
1029         return false;
1030       break;
1031
1032     case ARRAY_TYPE:
1033       /* Target types must match incl. qualifiers.  */
1034       if (!comp_array_types (t1, t2, !!(strict & COMPARE_REDECLARATION)))
1035         return false;
1036       break;
1037
1038     case TEMPLATE_TYPE_PARM:
1039       if (TEMPLATE_TYPE_IDX (t1) != TEMPLATE_TYPE_IDX (t2)
1040           || TEMPLATE_TYPE_LEVEL (t1) != TEMPLATE_TYPE_LEVEL (t2))
1041         return false;
1042       break;
1043
1044     case TYPENAME_TYPE:
1045       if (!cp_tree_equal (TYPENAME_TYPE_FULLNAME (t1),
1046                           TYPENAME_TYPE_FULLNAME (t2)))
1047         return false;
1048       if (!same_type_p (TYPE_CONTEXT (t1), TYPE_CONTEXT (t2)))
1049         return false;
1050       break;
1051
1052     case UNBOUND_CLASS_TEMPLATE:
1053       if (!cp_tree_equal (TYPE_IDENTIFIER (t1), TYPE_IDENTIFIER (t2)))
1054         return false;
1055       if (!same_type_p (TYPE_CONTEXT (t1), TYPE_CONTEXT (t2)))
1056         return false;
1057       break;
1058
1059     case COMPLEX_TYPE:
1060       if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
1061         return false;
1062       break;
1063
1064     case VECTOR_TYPE:
1065       if (TYPE_VECTOR_SUBPARTS (t1) != TYPE_VECTOR_SUBPARTS (t2)
1066           || !same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
1067         return false;
1068       break;
1069
1070     default:
1071       return false;
1072     }
1073
1074   /* If we get here, we know that from a target independent POV the
1075      types are the same.  Make sure the target attributes are also
1076      the same.  */
1077   return targetm.comp_type_attributes (t1, t2);
1078 }
1079
1080 /* Returns 1 if TYPE1 is at least as qualified as TYPE2.  */
1081
1082 bool
1083 at_least_as_qualified_p (tree type1, tree type2)
1084 {
1085   int q1 = cp_type_quals (type1);
1086   int q2 = cp_type_quals (type2);
1087
1088   /* All qualifiers for TYPE2 must also appear in TYPE1.  */
1089   return (q1 & q2) == q2;
1090 }
1091
1092 /* Returns 1 if TYPE1 is more cv-qualified than TYPE2, -1 if TYPE2 is
1093    more cv-qualified that TYPE1, and 0 otherwise.  */
1094
1095 int
1096 comp_cv_qualification (tree type1, tree type2)
1097 {
1098   int q1 = cp_type_quals (type1);
1099   int q2 = cp_type_quals (type2);
1100
1101   if (q1 == q2)
1102     return 0;
1103
1104   if ((q1 & q2) == q2)
1105     return 1;
1106   else if ((q1 & q2) == q1)
1107     return -1;
1108
1109   return 0;
1110 }
1111
1112 /* Returns 1 if the cv-qualification signature of TYPE1 is a proper
1113    subset of the cv-qualification signature of TYPE2, and the types
1114    are similar.  Returns -1 if the other way 'round, and 0 otherwise.  */
1115
1116 int
1117 comp_cv_qual_signature (tree type1, tree type2)
1118 {
1119   if (comp_ptr_ttypes_real (type2, type1, -1))
1120     return 1;
1121   else if (comp_ptr_ttypes_real (type1, type2, -1))
1122     return -1;
1123   else
1124     return 0;
1125 }
1126
1127 /* If two types share a common base type, return that basetype.
1128    If there is not a unique most-derived base type, this function
1129    returns ERROR_MARK_NODE.  */
1130
1131 static tree
1132 common_base_type (tree tt1, tree tt2)
1133 {
1134   tree best = NULL_TREE;
1135   int i;
1136
1137   /* If one is a baseclass of another, that's good enough.  */
1138   if (UNIQUELY_DERIVED_FROM_P (tt1, tt2))
1139     return tt1;
1140   if (UNIQUELY_DERIVED_FROM_P (tt2, tt1))
1141     return tt2;
1142
1143   /* Otherwise, try to find a unique baseclass of TT1
1144      that is shared by TT2, and follow that down.  */
1145   for (i = BINFO_N_BASE_BINFOS (TYPE_BINFO (tt1))-1; i >= 0; i--)
1146     {
1147       tree basetype = BINFO_TYPE (BINFO_BASE_BINFO (TYPE_BINFO (tt1), i));
1148       tree trial = common_base_type (basetype, tt2);
1149
1150       if (trial)
1151         {
1152           if (trial == error_mark_node)
1153             return trial;
1154           if (best == NULL_TREE)
1155             best = trial;
1156           else if (best != trial)
1157             return error_mark_node;
1158         }
1159     }
1160
1161   /* Same for TT2.  */
1162   for (i = BINFO_N_BASE_BINFOS (TYPE_BINFO (tt2))-1; i >= 0; i--)
1163     {
1164       tree basetype = BINFO_TYPE (BINFO_BASE_BINFO (TYPE_BINFO (tt2), i));
1165       tree trial = common_base_type (tt1, basetype);
1166
1167       if (trial)
1168         {
1169           if (trial == error_mark_node)
1170             return trial;
1171           if (best == NULL_TREE)
1172             best = trial;
1173           else if (best != trial)
1174             return error_mark_node;
1175         }
1176     }
1177   return best;
1178 }
1179 \f
1180 /* Subroutines of `comptypes'.  */
1181
1182 /* Return true if two parameter type lists PARMS1 and PARMS2 are
1183    equivalent in the sense that functions with those parameter types
1184    can have equivalent types.  The two lists must be equivalent,
1185    element by element.  */
1186
1187 bool
1188 compparms (tree parms1, tree parms2)
1189 {
1190   tree t1, t2;
1191
1192   /* An unspecified parmlist matches any specified parmlist
1193      whose argument types don't need default promotions.  */
1194
1195   for (t1 = parms1, t2 = parms2;
1196        t1 || t2;
1197        t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2))
1198     {
1199       /* If one parmlist is shorter than the other,
1200          they fail to match.  */
1201       if (!t1 || !t2)
1202         return false;
1203       if (!same_type_p (TREE_VALUE (t1), TREE_VALUE (t2)))
1204         return false;
1205     }
1206   return true;
1207 }
1208
1209 \f
1210 /* Process a sizeof or alignof expression where the operand is a
1211    type.  */
1212
1213 tree
1214 cxx_sizeof_or_alignof_type (tree type, enum tree_code op, bool complain)
1215 {
1216   enum tree_code type_code;
1217   tree value;
1218   const char *op_name;
1219
1220   gcc_assert (op == SIZEOF_EXPR || op == ALIGNOF_EXPR);
1221   if (type == error_mark_node)
1222     return error_mark_node;
1223
1224   if (processing_template_decl)
1225     {
1226       value = build_min (op, size_type_node, type);
1227       TREE_READONLY (value) = 1;
1228       return value;
1229     }
1230
1231   op_name = operator_name_info[(int) op].name;
1232
1233   type = non_reference (type);
1234   type_code = TREE_CODE (type);
1235
1236   if (type_code == METHOD_TYPE)
1237     {
1238       if (complain && (pedantic || warn_pointer_arith))
1239         pedwarn ("invalid application of %qs to a member function", op_name);
1240       value = size_one_node;
1241     }
1242   else
1243     value = c_sizeof_or_alignof_type (complete_type (type), op, complain);
1244
1245   return value;
1246 }
1247
1248 /* Process a sizeof or alignof expression where the operand is an
1249    expression.  */
1250
1251 tree
1252 cxx_sizeof_or_alignof_expr (tree e, enum tree_code op)
1253 {
1254   const char *op_name = operator_name_info[(int) op].name;
1255
1256   if (e == error_mark_node)
1257     return error_mark_node;
1258
1259   if (processing_template_decl)
1260     {
1261       e = build_min (op, size_type_node, e);
1262       TREE_SIDE_EFFECTS (e) = 0;
1263       TREE_READONLY (e) = 1;
1264
1265       return e;
1266     }
1267
1268   if (TREE_CODE (e) == COMPONENT_REF
1269       && TREE_CODE (TREE_OPERAND (e, 1)) == FIELD_DECL
1270       && DECL_C_BIT_FIELD (TREE_OPERAND (e, 1)))
1271     {
1272       error ("invalid application of %qs to a bit-field", op_name);
1273       e = char_type_node;
1274     }
1275   else if (is_overloaded_fn (e))
1276     {
1277       pedwarn ("ISO C++ forbids applying %qs to an expression of "
1278                "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 (type == error_mark_node)
1336     return error_mark_node;
1337
1338   if (type_unknown_p (exp))
1339     {
1340       cxx_incomplete_type_error (exp, TREE_TYPE (exp));
1341       return error_mark_node;
1342     }
1343
1344   exp = integral_constant_value (exp);
1345
1346   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
1347      Leave such NOP_EXPRs, since RHS is being used in non-lvalue context.  */
1348
1349   if (code == VOID_TYPE)
1350     {
1351       error ("void value not ignored as it ought to be");
1352       return error_mark_node;
1353     }
1354   if (invalid_nonstatic_memfn_p (exp))
1355     return error_mark_node;
1356   if (code == FUNCTION_TYPE || is_overloaded_fn (exp))
1357     return build_unary_op (ADDR_EXPR, exp, 0);
1358   if (code == ARRAY_TYPE)
1359     {
1360       tree adr;
1361       tree ptrtype;
1362
1363       if (TREE_CODE (exp) == INDIRECT_REF)
1364         return build_nop (build_pointer_type (TREE_TYPE (type)),
1365                           TREE_OPERAND (exp, 0));
1366
1367       if (TREE_CODE (exp) == COMPOUND_EXPR)
1368         {
1369           tree op1 = decay_conversion (TREE_OPERAND (exp, 1));
1370           return build2 (COMPOUND_EXPR, TREE_TYPE (op1),
1371                          TREE_OPERAND (exp, 0), op1);
1372         }
1373
1374       if (!lvalue_p (exp)
1375           && ! (TREE_CODE (exp) == CONSTRUCTOR && TREE_STATIC (exp)))
1376         {
1377           error ("invalid use of non-lvalue array");
1378           return error_mark_node;
1379         }
1380
1381       ptrtype = build_pointer_type (TREE_TYPE (type));
1382
1383       if (TREE_CODE (exp) == VAR_DECL)
1384         {
1385           if (!cxx_mark_addressable (exp))
1386             return error_mark_node;
1387           adr = build_nop (ptrtype, build_address (exp));
1388           return adr;
1389         }
1390       /* This way is better for a COMPONENT_REF since it can
1391          simplify the offset for a component.  */
1392       adr = build_unary_op (ADDR_EXPR, exp, 1);
1393       return cp_convert (ptrtype, adr);
1394     }
1395
1396   /* [basic.lval]: Class rvalues can have cv-qualified types; non-class
1397      rvalues always have cv-unqualified types.  */
1398   if (! CLASS_TYPE_P (type))
1399     exp = cp_convert (TYPE_MAIN_VARIANT (type), exp);
1400
1401   return exp;
1402 }
1403
1404 tree
1405 default_conversion (tree exp)
1406 {
1407   exp = decay_conversion (exp);
1408
1409   if (INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (exp)))
1410     exp = perform_integral_promotions (exp);
1411
1412   return exp;
1413 }
1414
1415 /* EXPR is an expression with an integral or enumeration type.
1416    Perform the integral promotions in [conv.prom], and return the
1417    converted value.  */
1418
1419 tree
1420 perform_integral_promotions (tree expr)
1421 {
1422   tree type;
1423   tree promoted_type;
1424
1425   type = TREE_TYPE (expr);
1426   gcc_assert (INTEGRAL_OR_ENUMERATION_TYPE_P (type));
1427   promoted_type = type_promotes_to (type);
1428   if (type != promoted_type)
1429     expr = cp_convert (promoted_type, expr);
1430   return expr;
1431 }
1432
1433 /* Take the address of an inline function without setting TREE_ADDRESSABLE
1434    or TREE_USED.  */
1435
1436 tree
1437 inline_conversion (tree exp)
1438 {
1439   if (TREE_CODE (exp) == FUNCTION_DECL)
1440     exp = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (exp)), exp);
1441
1442   return exp;
1443 }
1444
1445 /* Returns nonzero iff exp is a STRING_CST or the result of applying
1446    decay_conversion to one.  */
1447
1448 int
1449 string_conv_p (tree totype, tree exp, int warn)
1450 {
1451   tree t;
1452
1453   if (! flag_const_strings || TREE_CODE (totype) != POINTER_TYPE)
1454     return 0;
1455
1456   t = TREE_TYPE (totype);
1457   if (!same_type_p (t, char_type_node)
1458       && !same_type_p (t, wchar_type_node))
1459     return 0;
1460
1461   if (TREE_CODE (exp) == STRING_CST)
1462     {
1463       /* Make sure that we don't try to convert between char and wchar_t.  */
1464       if (!same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (exp))), t))
1465         return 0;
1466     }
1467   else
1468     {
1469       /* Is this a string constant which has decayed to 'const char *'?  */
1470       t = build_pointer_type (build_qualified_type (t, TYPE_QUAL_CONST));
1471       if (!same_type_p (TREE_TYPE (exp), t))
1472         return 0;
1473       STRIP_NOPS (exp);
1474       if (TREE_CODE (exp) != ADDR_EXPR
1475           || TREE_CODE (TREE_OPERAND (exp, 0)) != STRING_CST)
1476         return 0;
1477     }
1478
1479   /* This warning is not very useful, as it complains about printf.  */
1480   if (warn && warn_write_strings)
1481     warning ("deprecated conversion from string constant to %qT'", totype);
1482
1483   return 1;
1484 }
1485
1486 /* Given a COND_EXPR, MIN_EXPR, or MAX_EXPR in T, return it in a form that we
1487    can, for example, use as an lvalue.  This code used to be in
1488    unary_complex_lvalue, but we needed it to deal with `a = (d == c) ? b : c'
1489    expressions, where we're dealing with aggregates.  But now it's again only
1490    called from unary_complex_lvalue.  The case (in particular) that led to
1491    this was with CODE == ADDR_EXPR, since it's not an lvalue when we'd
1492    get it there.  */
1493
1494 static tree
1495 rationalize_conditional_expr (enum tree_code code, tree t)
1496 {
1497   /* For MIN_EXPR or MAX_EXPR, fold-const.c has arranged things so that
1498      the first operand is always the one to be used if both operands
1499      are equal, so we know what conditional expression this used to be.  */
1500   if (TREE_CODE (t) == MIN_EXPR || TREE_CODE (t) == MAX_EXPR)
1501     {
1502       /* The following code is incorrect if either operand side-effects.  */
1503       gcc_assert (!TREE_SIDE_EFFECTS (TREE_OPERAND (t, 0))
1504                   && !TREE_SIDE_EFFECTS (TREE_OPERAND (t, 1)));
1505       return
1506         build_conditional_expr (build_x_binary_op ((TREE_CODE (t) == MIN_EXPR
1507                                                     ? LE_EXPR : GE_EXPR),
1508                                                    TREE_OPERAND (t, 0),
1509                                                    TREE_OPERAND (t, 1),
1510                                                    /*overloaded_p=*/NULL),
1511                             build_unary_op (code, TREE_OPERAND (t, 0), 0),
1512                             build_unary_op (code, TREE_OPERAND (t, 1), 0));
1513     }
1514
1515   return
1516     build_conditional_expr (TREE_OPERAND (t, 0),
1517                             build_unary_op (code, TREE_OPERAND (t, 1), 0),
1518                             build_unary_op (code, TREE_OPERAND (t, 2), 0));
1519 }
1520
1521 /* Given the TYPE of an anonymous union field inside T, return the
1522    FIELD_DECL for the field.  If not found return NULL_TREE.  Because
1523    anonymous unions can nest, we must also search all anonymous unions
1524    that are directly reachable.  */
1525
1526 tree
1527 lookup_anon_field (tree t, tree type)
1528 {
1529   tree field;
1530
1531   for (field = TYPE_FIELDS (t); field; field = TREE_CHAIN (field))
1532     {
1533       if (TREE_STATIC (field))
1534         continue;
1535       if (TREE_CODE (field) != FIELD_DECL || DECL_ARTIFICIAL (field))
1536         continue;
1537
1538       /* If we find it directly, return the field.  */
1539       if (DECL_NAME (field) == NULL_TREE
1540           && type == TYPE_MAIN_VARIANT (TREE_TYPE (field)))
1541         {
1542           return field;
1543         }
1544
1545       /* Otherwise, it could be nested, search harder.  */
1546       if (DECL_NAME (field) == NULL_TREE
1547           && ANON_AGGR_TYPE_P (TREE_TYPE (field)))
1548         {
1549           tree subfield = lookup_anon_field (TREE_TYPE (field), type);
1550           if (subfield)
1551             return subfield;
1552         }
1553     }
1554   return NULL_TREE;
1555 }
1556
1557 /* Build an expression representing OBJECT.MEMBER.  OBJECT is an
1558    expression; MEMBER is a DECL or baselink.  If ACCESS_PATH is
1559    non-NULL, it indicates the path to the base used to name MEMBER.
1560    If PRESERVE_REFERENCE is true, the expression returned will have
1561    REFERENCE_TYPE if the MEMBER does.  Otherwise, the expression
1562    returned will have the type referred to by the reference.
1563
1564    This function does not perform access control; that is either done
1565    earlier by the parser when the name of MEMBER is resolved to MEMBER
1566    itself, or later when overload resolution selects one of the
1567    functions indicated by MEMBER.  */
1568
1569 tree
1570 build_class_member_access_expr (tree object, tree member,
1571                                 tree access_path, bool preserve_reference)
1572 {
1573   tree object_type;
1574   tree member_scope;
1575   tree result = NULL_TREE;
1576
1577   if (object == error_mark_node || member == error_mark_node)
1578     return error_mark_node;
1579
1580   gcc_assert (DECL_P (member) || BASELINK_P (member));
1581
1582   /* [expr.ref]
1583
1584      The type of the first expression shall be "class object" (of a
1585      complete type).  */
1586   object_type = TREE_TYPE (object);
1587   if (!currently_open_class (object_type)
1588       && !complete_type_or_else (object_type, object))
1589     return error_mark_node;
1590   if (!CLASS_TYPE_P (object_type))
1591     {
1592       error ("request for member %qD in %qE, which is of non-class type %qT",
1593              member, object, object_type);
1594       return error_mark_node;
1595     }
1596
1597   /* The standard does not seem to actually say that MEMBER must be a
1598      member of OBJECT_TYPE.  However, that is clearly what is
1599      intended.  */
1600   if (DECL_P (member))
1601     {
1602       member_scope = DECL_CLASS_CONTEXT (member);
1603       mark_used (member);
1604       if (TREE_DEPRECATED (member))
1605         warn_deprecated_use (member);
1606     }
1607   else
1608     member_scope = BINFO_TYPE (BASELINK_BINFO (member));
1609   /* If MEMBER is from an anonymous aggregate, MEMBER_SCOPE will
1610      presently be the anonymous union.  Go outwards until we find a
1611      type related to OBJECT_TYPE.  */
1612   while (ANON_AGGR_TYPE_P (member_scope)
1613          && !same_type_ignoring_top_level_qualifiers_p (member_scope,
1614                                                         object_type))
1615     member_scope = TYPE_CONTEXT (member_scope);
1616   if (!member_scope || !DERIVED_FROM_P (member_scope, object_type))
1617     {
1618       if (TREE_CODE (member) == FIELD_DECL)
1619         error ("invalid use of nonstatic data member %qE", member);
1620       else
1621         error ("%qD is not a member of %qT", member, object_type);
1622       return error_mark_node;
1623     }
1624
1625   /* Transform `(a, b).x' into `(*(a, &b)).x', `(a ? b : c).x' into
1626      `(*(a ?  &b : &c)).x', and so on.  A COND_EXPR is only an lvalue
1627      in the frontend; only _DECLs and _REFs are lvalues in the backend.  */
1628   {
1629     tree temp = unary_complex_lvalue (ADDR_EXPR, object);
1630     if (temp)
1631       object = build_indirect_ref (temp, NULL);
1632   }
1633
1634   /* In [expr.ref], there is an explicit list of the valid choices for
1635      MEMBER.  We check for each of those cases here.  */
1636   if (TREE_CODE (member) == VAR_DECL)
1637     {
1638       /* A static data member.  */
1639       result = member;
1640       /* If OBJECT has side-effects, they are supposed to occur.  */
1641       if (TREE_SIDE_EFFECTS (object))
1642         result = build2 (COMPOUND_EXPR, TREE_TYPE (result), object, result);
1643     }
1644   else if (TREE_CODE (member) == FIELD_DECL)
1645     {
1646       /* A non-static data member.  */
1647       bool null_object_p;
1648       int type_quals;
1649       tree member_type;
1650
1651       null_object_p = (TREE_CODE (object) == INDIRECT_REF
1652                        && integer_zerop (TREE_OPERAND (object, 0)));
1653
1654       /* Convert OBJECT to the type of MEMBER.  */
1655       if (!same_type_p (TYPE_MAIN_VARIANT (object_type),
1656                         TYPE_MAIN_VARIANT (member_scope)))
1657         {
1658           tree binfo;
1659           base_kind kind;
1660
1661           binfo = lookup_base (access_path ? access_path : object_type,
1662                                member_scope, ba_unique,  &kind);
1663           if (binfo == error_mark_node)
1664             return error_mark_node;
1665
1666           /* It is invalid to try to get to a virtual base of a
1667              NULL object.  The most common cause is invalid use of
1668              offsetof macro.  */
1669           if (null_object_p && kind == bk_via_virtual)
1670             {
1671               error ("invalid access to non-static data member %qD of "
1672                      "NULL object",
1673                      member);
1674               error ("(perhaps the %<offsetof%> macro was used incorrectly)");
1675               return error_mark_node;
1676             }
1677
1678           /* Convert to the base.  */
1679           object = build_base_path (PLUS_EXPR, object, binfo,
1680                                     /*nonnull=*/1);
1681           /* If we found the base successfully then we should be able
1682              to convert to it successfully.  */
1683           gcc_assert (object != error_mark_node);
1684         }
1685
1686       /* Complain about other invalid uses of offsetof, even though they will
1687          give the right answer.  Note that we complain whether or not they
1688          actually used the offsetof macro, since there's no way to know at this
1689          point.  So we just give a warning, instead of a pedwarn.  */
1690       /* Do not produce this warning for base class field references, because
1691          we know for a fact that didn't come from offsetof.  This does occur
1692          in various testsuite cases where a null object is passed where a
1693          vtable access is required.  */
1694       if (null_object_p && warn_invalid_offsetof
1695           && CLASSTYPE_NON_POD_P (object_type)
1696           && !DECL_FIELD_IS_BASE (member)
1697           && !skip_evaluation)
1698         {
1699           warning ("invalid access to non-static data member %qD of NULL object",
1700                    member);
1701           warning  ("(perhaps the %<offsetof%> macro was used incorrectly)");
1702         }
1703
1704       /* If MEMBER is from an anonymous aggregate, we have converted
1705          OBJECT so that it refers to the class containing the
1706          anonymous union.  Generate a reference to the anonymous union
1707          itself, and recur to find MEMBER.  */
1708       if (ANON_AGGR_TYPE_P (DECL_CONTEXT (member))
1709           /* When this code is called from build_field_call, the
1710              object already has the type of the anonymous union.
1711              That is because the COMPONENT_REF was already
1712              constructed, and was then disassembled before calling
1713              build_field_call.  After the function-call code is
1714              cleaned up, this waste can be eliminated.  */
1715           && (!same_type_ignoring_top_level_qualifiers_p
1716               (TREE_TYPE (object), DECL_CONTEXT (member))))
1717         {
1718           tree anonymous_union;
1719
1720           anonymous_union = lookup_anon_field (TREE_TYPE (object),
1721                                                DECL_CONTEXT (member));
1722           object = build_class_member_access_expr (object,
1723                                                    anonymous_union,
1724                                                    /*access_path=*/NULL_TREE,
1725                                                    preserve_reference);
1726         }
1727
1728       /* Compute the type of the field, as described in [expr.ref].  */
1729       type_quals = TYPE_UNQUALIFIED;
1730       member_type = TREE_TYPE (member);
1731       if (TREE_CODE (member_type) != REFERENCE_TYPE)
1732         {
1733           type_quals = (cp_type_quals (member_type)
1734                         | cp_type_quals (object_type));
1735
1736           /* A field is const (volatile) if the enclosing object, or the
1737              field itself, is const (volatile).  But, a mutable field is
1738              not const, even within a const object.  */
1739           if (DECL_MUTABLE_P (member))
1740             type_quals &= ~TYPE_QUAL_CONST;
1741           member_type = cp_build_qualified_type (member_type, type_quals);
1742         }
1743
1744       result = build3 (COMPONENT_REF, member_type, object, member,
1745                        NULL_TREE);
1746       result = fold_if_not_in_template (result);
1747
1748       /* Mark the expression const or volatile, as appropriate.  Even
1749          though we've dealt with the type above, we still have to mark the
1750          expression itself.  */
1751       if (type_quals & TYPE_QUAL_CONST)
1752         TREE_READONLY (result) = 1;
1753       if (type_quals & TYPE_QUAL_VOLATILE)
1754         TREE_THIS_VOLATILE (result) = 1;
1755     }
1756   else if (BASELINK_P (member))
1757     {
1758       /* The member is a (possibly overloaded) member function.  */
1759       tree functions;
1760       tree type;
1761
1762       /* If the MEMBER is exactly one static member function, then we
1763          know the type of the expression.  Otherwise, we must wait
1764          until overload resolution has been performed.  */
1765       functions = BASELINK_FUNCTIONS (member);
1766       if (TREE_CODE (functions) == FUNCTION_DECL
1767           && DECL_STATIC_FUNCTION_P (functions))
1768         type = TREE_TYPE (functions);
1769       else
1770         type = unknown_type_node;
1771       /* Note that we do not convert OBJECT to the BASELINK_BINFO
1772          base.  That will happen when the function is called.  */
1773       result = build3 (COMPONENT_REF, type, object, member, NULL_TREE);
1774     }
1775   else if (TREE_CODE (member) == CONST_DECL)
1776     {
1777       /* The member is an enumerator.  */
1778       result = member;
1779       /* If OBJECT has side-effects, they are supposed to occur.  */
1780       if (TREE_SIDE_EFFECTS (object))
1781         result = build2 (COMPOUND_EXPR, TREE_TYPE (result),
1782                          object, result);
1783     }
1784   else
1785     {
1786       error ("invalid use of %qD", member);
1787       return error_mark_node;
1788     }
1789
1790   if (!preserve_reference)
1791     /* [expr.ref]
1792
1793        If E2 is declared to have type "reference to T", then ... the
1794        type of E1.E2 is T.  */
1795     result = convert_from_reference (result);
1796
1797   return result;
1798 }
1799
1800 /* Return the destructor denoted by OBJECT.SCOPE::~DTOR_NAME, or, if
1801    SCOPE is NULL, by OBJECT.~DTOR_NAME.  */
1802
1803 static tree
1804 lookup_destructor (tree object, tree scope, tree dtor_name)
1805 {
1806   tree object_type = TREE_TYPE (object);
1807   tree dtor_type = TREE_OPERAND (dtor_name, 0);
1808   tree expr;
1809
1810   if (scope && !check_dtor_name (scope, dtor_name))
1811     {
1812       error ("qualified type %qT does not match destructor name ~%qT",
1813              scope, dtor_type);
1814       return error_mark_node;
1815     }
1816   if (!DERIVED_FROM_P (dtor_type, TYPE_MAIN_VARIANT (object_type)))
1817     {
1818       error ("the type being destroyed is %qT, but the destructor refers to %qT",
1819              TYPE_MAIN_VARIANT (object_type), dtor_type);
1820       return error_mark_node;
1821     }
1822   expr = lookup_member (dtor_type, complete_dtor_identifier,
1823                         /*protect=*/1, /*want_type=*/false);
1824   expr = (adjust_result_of_qualified_name_lookup
1825           (expr, dtor_type, object_type));
1826   return expr;
1827 }
1828
1829 /* This function is called by the parser to process a class member
1830    access expression of the form OBJECT.NAME.  NAME is a node used by
1831    the parser to represent a name; it is not yet a DECL.  It may,
1832    however, be a BASELINK where the BASELINK_FUNCTIONS is a
1833    TEMPLATE_ID_EXPR.  Templates must be looked up by the parser, and
1834    there is no reason to do the lookup twice, so the parser keeps the
1835    BASELINK.  */
1836
1837 tree
1838 finish_class_member_access_expr (tree object, tree name)
1839 {
1840   tree expr;
1841   tree object_type;
1842   tree member;
1843   tree access_path = NULL_TREE;
1844   tree orig_object = object;
1845   tree orig_name = name;
1846
1847   if (object == error_mark_node || name == error_mark_node)
1848     return error_mark_node;
1849
1850   object_type = TREE_TYPE (object);
1851
1852   if (processing_template_decl)
1853     {
1854       if (/* If OBJECT_TYPE is dependent, so is OBJECT.NAME.  */
1855           dependent_type_p (object_type)
1856           /* If NAME is just an IDENTIFIER_NODE, then the expression
1857              is dependent.  */
1858           || TREE_CODE (object) == IDENTIFIER_NODE
1859           /* If NAME is "f<args>", where either 'f' or 'args' is
1860              dependent, then the expression is dependent.  */
1861           || (TREE_CODE (name) == TEMPLATE_ID_EXPR
1862               && dependent_template_id_p (TREE_OPERAND (name, 0),
1863                                           TREE_OPERAND (name, 1)))
1864           /* If NAME is "T::X" where "T" is dependent, then the
1865              expression is dependent.  */
1866           || (TREE_CODE (name) == SCOPE_REF
1867               && TYPE_P (TREE_OPERAND (name, 0))
1868               && dependent_type_p (TREE_OPERAND (name, 0))))
1869         return build_min_nt (COMPONENT_REF, object, name, NULL_TREE);
1870       object = build_non_dependent_expr (object);
1871     }
1872
1873   /* [expr.ref]
1874
1875      The type of the first expression shall be "class object" (of a
1876      complete type).  */
1877   if (!currently_open_class (object_type)
1878       && !complete_type_or_else (object_type, object))
1879     return error_mark_node;
1880   if (!CLASS_TYPE_P (object_type))
1881     {
1882       error ("request for member %qD in %qE, which is of non-class type %qT",
1883              name, object, object_type);
1884       return error_mark_node;
1885     }
1886
1887   if (BASELINK_P (name))
1888     {
1889       /* A member function that has already been looked up.  */
1890       gcc_assert (TREE_CODE (BASELINK_FUNCTIONS (name)) == TEMPLATE_ID_EXPR);
1891       member = name;
1892     }
1893   else
1894     {
1895       bool is_template_id = false;
1896       tree template_args = NULL_TREE;
1897       tree scope;
1898
1899       if (TREE_CODE (name) == TEMPLATE_ID_EXPR)
1900         {
1901           is_template_id = true;
1902           template_args = TREE_OPERAND (name, 1);
1903           name = TREE_OPERAND (name, 0);
1904
1905           if (TREE_CODE (name) == OVERLOAD)
1906             name = DECL_NAME (get_first_fn (name));
1907           else if (DECL_P (name))
1908             name = DECL_NAME (name);
1909         }
1910
1911       if (TREE_CODE (name) == SCOPE_REF)
1912         {
1913           /* A qualified name.  The qualifying class or namespace `S' has
1914              already been looked up; it is either a TYPE or a
1915              NAMESPACE_DECL.  The member name is either an IDENTIFIER_NODE
1916              or a BIT_NOT_EXPR.  */
1917           scope = TREE_OPERAND (name, 0);
1918           name = TREE_OPERAND (name, 1);
1919           gcc_assert (CLASS_TYPE_P (scope)
1920                       || TREE_CODE (scope) == NAMESPACE_DECL);
1921           gcc_assert (TREE_CODE (name) == IDENTIFIER_NODE
1922                       || TREE_CODE (name) == BIT_NOT_EXPR);
1923
1924           /* If SCOPE is a namespace, then the qualified name does not
1925              name a member of OBJECT_TYPE.  */
1926           if (TREE_CODE (scope) == NAMESPACE_DECL)
1927             {
1928               error ("%<%D::%D%> is not a member of %qT",
1929                      scope, name, object_type);
1930               return error_mark_node;
1931             }
1932
1933           /* Find the base of OBJECT_TYPE corresponding to SCOPE.  */
1934           access_path = lookup_base (object_type, scope, ba_check, NULL);
1935           if (access_path == error_mark_node)
1936             return error_mark_node;
1937           if (!access_path)
1938             {
1939               error ("%qT is not a base of %qT", scope, object_type);
1940               return error_mark_node;
1941             }
1942         }
1943       else
1944         {
1945           scope = NULL_TREE;
1946           access_path = object_type;
1947         }
1948
1949       if (TREE_CODE (name) == BIT_NOT_EXPR)
1950         member = lookup_destructor (object, scope, name);
1951       else
1952         {
1953           /* Look up the member.  */
1954           member = lookup_member (access_path, name, /*protect=*/1,
1955                                   /*want_type=*/false);
1956           if (member == NULL_TREE)
1957             {
1958               error ("%qD has no member named %qE", object_type, name);
1959               return error_mark_node;
1960             }
1961           if (member == error_mark_node)
1962             return error_mark_node;
1963         }
1964
1965       if (is_template_id)
1966         {
1967           tree template = member;
1968
1969           if (BASELINK_P (template))
1970             template = lookup_template_function (template, template_args);
1971           else
1972             {
1973               error ("%qD is not a member template function", name);
1974               return error_mark_node;
1975             }
1976         }
1977     }
1978
1979   if (TREE_DEPRECATED (member))
1980     warn_deprecated_use (member);
1981
1982   expr = build_class_member_access_expr (object, member, access_path,
1983                                          /*preserve_reference=*/false);
1984   if (processing_template_decl && expr != error_mark_node)
1985     return build_min_non_dep (COMPONENT_REF, expr,
1986                               orig_object, orig_name, NULL_TREE);
1987   return expr;
1988 }
1989
1990 /* Return an expression for the MEMBER_NAME field in the internal
1991    representation of PTRMEM, a pointer-to-member function.  (Each
1992    pointer-to-member function type gets its own RECORD_TYPE so it is
1993    more convenient to access the fields by name than by FIELD_DECL.)
1994    This routine converts the NAME to a FIELD_DECL and then creates the
1995    node for the complete expression.  */
1996
1997 tree
1998 build_ptrmemfunc_access_expr (tree ptrmem, tree member_name)
1999 {
2000   tree ptrmem_type;
2001   tree member;
2002   tree member_type;
2003
2004   /* This code is a stripped down version of
2005      build_class_member_access_expr.  It does not work to use that
2006      routine directly because it expects the object to be of class
2007      type.  */
2008   ptrmem_type = TREE_TYPE (ptrmem);
2009   gcc_assert (TYPE_PTRMEMFUNC_P (ptrmem_type));
2010   member = lookup_member (ptrmem_type, member_name, /*protect=*/0,
2011                           /*want_type=*/false);
2012   member_type = cp_build_qualified_type (TREE_TYPE (member),
2013                                          cp_type_quals (ptrmem_type));
2014   return fold_build3 (COMPONENT_REF, member_type,
2015                       ptrmem, member, NULL_TREE);
2016 }
2017
2018 /* Given an expression PTR for a pointer, return an expression
2019    for the value pointed to.
2020    ERRORSTRING is the name of the operator to appear in error messages.
2021
2022    This function may need to overload OPERATOR_FNNAME.
2023    Must also handle REFERENCE_TYPEs for C++.  */
2024
2025 tree
2026 build_x_indirect_ref (tree expr, const char *errorstring)
2027 {
2028   tree orig_expr = expr;
2029   tree rval;
2030
2031   if (processing_template_decl)
2032     {
2033       if (type_dependent_expression_p (expr))
2034         return build_min_nt (INDIRECT_REF, expr);
2035       expr = build_non_dependent_expr (expr);
2036     }
2037
2038   rval = build_new_op (INDIRECT_REF, LOOKUP_NORMAL, expr, NULL_TREE,
2039                        NULL_TREE, /*overloaded_p=*/NULL);
2040   if (!rval)
2041     rval = build_indirect_ref (expr, errorstring);
2042
2043   if (processing_template_decl && rval != error_mark_node)
2044     return build_min_non_dep (INDIRECT_REF, rval, orig_expr);
2045   else
2046     return rval;
2047 }
2048
2049 tree
2050 build_indirect_ref (tree ptr, const char *errorstring)
2051 {
2052   tree pointer, type;
2053
2054   if (ptr == error_mark_node)
2055     return error_mark_node;
2056
2057   if (ptr == current_class_ptr)
2058     return current_class_ref;
2059
2060   pointer = (TREE_CODE (TREE_TYPE (ptr)) == REFERENCE_TYPE
2061              ? ptr : decay_conversion (ptr));
2062   type = TREE_TYPE (pointer);
2063
2064   if (POINTER_TYPE_P (type))
2065     {
2066       /* [expr.unary.op]
2067
2068          If the type of the expression is "pointer to T," the type
2069          of  the  result  is  "T."
2070
2071          We must use the canonical variant because certain parts of
2072          the back end, like fold, do pointer comparisons between
2073          types.  */
2074       tree t = canonical_type_variant (TREE_TYPE (type));
2075
2076       if (VOID_TYPE_P (t))
2077         {
2078           /* A pointer to incomplete type (other than cv void) can be
2079              dereferenced [expr.unary.op]/1  */
2080           error ("%qT is not a pointer-to-object type", type);
2081           return error_mark_node;
2082         }
2083       else if (TREE_CODE (pointer) == ADDR_EXPR
2084                && same_type_p (t, TREE_TYPE (TREE_OPERAND (pointer, 0))))
2085         /* The POINTER was something like `&x'.  We simplify `*&x' to
2086            `x'.  */
2087         return TREE_OPERAND (pointer, 0);
2088       else
2089         {
2090           tree ref = build1 (INDIRECT_REF, t, pointer);
2091
2092           /* We *must* set TREE_READONLY when dereferencing a pointer to const,
2093              so that we get the proper error message if the result is used
2094              to assign to.  Also, &* is supposed to be a no-op.  */
2095           TREE_READONLY (ref) = CP_TYPE_CONST_P (t);
2096           TREE_THIS_VOLATILE (ref) = CP_TYPE_VOLATILE_P (t);
2097           TREE_SIDE_EFFECTS (ref)
2098             = (TREE_THIS_VOLATILE (ref) || TREE_SIDE_EFFECTS (pointer));
2099           return ref;
2100         }
2101     }
2102   /* `pointer' won't be an error_mark_node if we were given a
2103      pointer to member, so it's cool to check for this here.  */
2104   else if (TYPE_PTR_TO_MEMBER_P (type))
2105     error ("invalid use of %qs on pointer to member", errorstring);
2106   else if (pointer != error_mark_node)
2107     {
2108       if (errorstring)
2109         error ("invalid type argument of %qs", errorstring);
2110       else
2111         error ("invalid type argument");
2112     }
2113   return error_mark_node;
2114 }
2115
2116 /* This handles expressions of the form "a[i]", which denotes
2117    an array reference.
2118
2119    This is logically equivalent in C to *(a+i), but we may do it differently.
2120    If A is a variable or a member, we generate a primitive ARRAY_REF.
2121    This avoids forcing the array out of registers, and can work on
2122    arrays that are not lvalues (for example, members of structures returned
2123    by functions).
2124
2125    If INDEX is of some user-defined type, it must be converted to
2126    integer type.  Otherwise, to make a compatible PLUS_EXPR, it
2127    will inherit the type of the array, which will be some pointer type.  */
2128
2129 tree
2130 build_array_ref (tree array, tree idx)
2131 {
2132   if (idx == 0)
2133     {
2134       error ("subscript missing in array reference");
2135       return error_mark_node;
2136     }
2137
2138   if (TREE_TYPE (array) == error_mark_node
2139       || TREE_TYPE (idx) == error_mark_node)
2140     return error_mark_node;
2141
2142   /* If ARRAY is a COMPOUND_EXPR or COND_EXPR, move our reference
2143      inside it.  */
2144   switch (TREE_CODE (array))
2145     {
2146     case COMPOUND_EXPR:
2147       {
2148         tree value = build_array_ref (TREE_OPERAND (array, 1), idx);
2149         return build2 (COMPOUND_EXPR, TREE_TYPE (value),
2150                        TREE_OPERAND (array, 0), value);
2151       }
2152
2153     case COND_EXPR:
2154       return build_conditional_expr
2155         (TREE_OPERAND (array, 0),
2156          build_array_ref (TREE_OPERAND (array, 1), idx),
2157          build_array_ref (TREE_OPERAND (array, 2), idx));
2158
2159     default:
2160       break;
2161     }
2162
2163   if (TREE_CODE (TREE_TYPE (array)) == ARRAY_TYPE)
2164     {
2165       tree rval, type;
2166
2167       /* Subscripting with type char is likely to lose
2168          on a machine where chars are signed.
2169          So warn on any machine, but optionally.
2170          Don't warn for unsigned char since that type is safe.
2171          Don't warn for signed char because anyone who uses that
2172          must have done so deliberately.  */
2173       if (warn_char_subscripts
2174           && TYPE_MAIN_VARIANT (TREE_TYPE (idx)) == char_type_node)
2175         warning ("array subscript has type %<char%>");
2176
2177       if (!INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (idx)))
2178         {
2179           error ("array subscript is not an integer");
2180           return error_mark_node;
2181         }
2182
2183       /* Apply integral promotions *after* noticing character types.
2184          (It is unclear why we do these promotions -- the standard
2185          does not say that we should.  In fact, the natural thing would
2186          seem to be to convert IDX to ptrdiff_t; we're performing
2187          pointer arithmetic.)  */
2188       idx = perform_integral_promotions (idx);
2189
2190       /* An array that is indexed by a non-constant
2191          cannot be stored in a register; we must be able to do
2192          address arithmetic on its address.
2193          Likewise an array of elements of variable size.  */
2194       if (TREE_CODE (idx) != INTEGER_CST
2195           || (COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (array)))
2196               && (TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (array))))
2197                   != INTEGER_CST)))
2198         {
2199           if (!cxx_mark_addressable (array))
2200             return error_mark_node;
2201         }
2202
2203       /* An array that is indexed by a constant value which is not within
2204          the array bounds cannot be stored in a register either; because we
2205          would get a crash in store_bit_field/extract_bit_field when trying
2206          to access a non-existent part of the register.  */
2207       if (TREE_CODE (idx) == INTEGER_CST
2208           && TYPE_DOMAIN (TREE_TYPE (array))
2209           && ! int_fits_type_p (idx, TYPE_DOMAIN (TREE_TYPE (array))))
2210         {
2211           if (!cxx_mark_addressable (array))
2212             return error_mark_node;
2213         }
2214
2215       if (pedantic && !lvalue_p (array))
2216         pedwarn ("ISO C++ forbids subscripting non-lvalue array");
2217
2218       /* Note in C++ it is valid to subscript a `register' array, since
2219          it is valid to take the address of something with that
2220          storage specification.  */
2221       if (extra_warnings)
2222         {
2223           tree foo = array;
2224           while (TREE_CODE (foo) == COMPONENT_REF)
2225             foo = TREE_OPERAND (foo, 0);
2226           if (TREE_CODE (foo) == VAR_DECL && DECL_REGISTER (foo))
2227             warning ("subscripting array declared %<register%>");
2228         }
2229
2230       type = TREE_TYPE (TREE_TYPE (array));
2231       rval = build4 (ARRAY_REF, type, array, idx, NULL_TREE, NULL_TREE);
2232       /* Array ref is const/volatile if the array elements are
2233          or if the array is..  */
2234       TREE_READONLY (rval)
2235         |= (CP_TYPE_CONST_P (type) | TREE_READONLY (array));
2236       TREE_SIDE_EFFECTS (rval)
2237         |= (CP_TYPE_VOLATILE_P (type) | TREE_SIDE_EFFECTS (array));
2238       TREE_THIS_VOLATILE (rval)
2239         |= (CP_TYPE_VOLATILE_P (type) | TREE_THIS_VOLATILE (array));
2240       return require_complete_type (fold_if_not_in_template (rval));
2241     }
2242
2243   {
2244     tree ar = default_conversion (array);
2245     tree ind = default_conversion (idx);
2246
2247     /* Put the integer in IND to simplify error checking.  */
2248     if (TREE_CODE (TREE_TYPE (ar)) == INTEGER_TYPE)
2249       {
2250         tree temp = ar;
2251         ar = ind;
2252         ind = temp;
2253       }
2254
2255     if (ar == error_mark_node)
2256       return ar;
2257
2258     if (TREE_CODE (TREE_TYPE (ar)) != POINTER_TYPE)
2259       {
2260         error ("subscripted value is neither array nor pointer");
2261         return error_mark_node;
2262       }
2263     if (TREE_CODE (TREE_TYPE (ind)) != INTEGER_TYPE)
2264       {
2265         error ("array subscript is not an integer");
2266         return error_mark_node;
2267       }
2268
2269     return build_indirect_ref (cp_build_binary_op (PLUS_EXPR, ar, ind),
2270                                "array indexing");
2271   }
2272 }
2273 \f
2274 /* Resolve a pointer to member function.  INSTANCE is the object
2275    instance to use, if the member points to a virtual member.
2276
2277    This used to avoid checking for virtual functions if basetype
2278    has no virtual functions, according to an earlier ANSI draft.
2279    With the final ISO C++ rules, such an optimization is
2280    incorrect: A pointer to a derived member can be static_cast
2281    to pointer-to-base-member, as long as the dynamic object
2282    later has the right member.  */
2283
2284 tree
2285 get_member_function_from_ptrfunc (tree *instance_ptrptr, tree function)
2286 {
2287   if (TREE_CODE (function) == OFFSET_REF)
2288     function = TREE_OPERAND (function, 1);
2289
2290   if (TYPE_PTRMEMFUNC_P (TREE_TYPE (function)))
2291     {
2292       tree idx, delta, e1, e2, e3, vtbl, basetype;
2293       tree fntype = TYPE_PTRMEMFUNC_FN_TYPE (TREE_TYPE (function));
2294
2295       tree instance_ptr = *instance_ptrptr;
2296       tree instance_save_expr = 0;
2297       if (instance_ptr == error_mark_node)
2298         {
2299           if (TREE_CODE (function) == PTRMEM_CST)
2300             {
2301               /* Extracting the function address from a pmf is only
2302                  allowed with -Wno-pmf-conversions. It only works for
2303                  pmf constants.  */
2304               e1 = build_addr_func (PTRMEM_CST_MEMBER (function));
2305               e1 = convert (fntype, e1);
2306               return e1;
2307             }
2308           else
2309             {
2310               error ("object missing in use of %qE", function);
2311               return error_mark_node;
2312             }
2313         }
2314
2315       if (TREE_SIDE_EFFECTS (instance_ptr))
2316         instance_ptr = instance_save_expr = save_expr (instance_ptr);
2317
2318       if (TREE_SIDE_EFFECTS (function))
2319         function = save_expr (function);
2320
2321       /* Start by extracting all the information from the PMF itself.  */
2322       e3 = pfn_from_ptrmemfunc (function);
2323       delta = build_ptrmemfunc_access_expr (function, delta_identifier);
2324       idx = build1 (NOP_EXPR, vtable_index_type, e3);
2325       switch (TARGET_PTRMEMFUNC_VBIT_LOCATION)
2326         {
2327         case ptrmemfunc_vbit_in_pfn:
2328           e1 = cp_build_binary_op (BIT_AND_EXPR, idx, integer_one_node);
2329           idx = cp_build_binary_op (MINUS_EXPR, idx, integer_one_node);
2330           break;
2331
2332         case ptrmemfunc_vbit_in_delta:
2333           e1 = cp_build_binary_op (BIT_AND_EXPR, delta, integer_one_node);
2334           delta = cp_build_binary_op (RSHIFT_EXPR, delta, integer_one_node);
2335           break;
2336
2337         default:
2338           gcc_unreachable ();
2339         }
2340
2341       /* Convert down to the right base before using the instance.  First
2342          use the type...  */
2343       basetype = TYPE_METHOD_BASETYPE (TREE_TYPE (fntype));
2344       basetype = lookup_base (TREE_TYPE (TREE_TYPE (instance_ptr)),
2345                               basetype, ba_check, NULL);
2346       instance_ptr = build_base_path (PLUS_EXPR, instance_ptr, basetype, 1);
2347       if (instance_ptr == error_mark_node)
2348         return error_mark_node;
2349       /* ...and then the delta in the PMF.  */
2350       instance_ptr = build2 (PLUS_EXPR, TREE_TYPE (instance_ptr),
2351                              instance_ptr, delta);
2352
2353       /* Hand back the adjusted 'this' argument to our caller.  */
2354       *instance_ptrptr = instance_ptr;
2355
2356       /* Next extract the vtable pointer from the object.  */
2357       vtbl = build1 (NOP_EXPR, build_pointer_type (vtbl_ptr_type_node),
2358                      instance_ptr);
2359       vtbl = build_indirect_ref (vtbl, NULL);
2360
2361       /* Finally, extract the function pointer from the vtable.  */
2362       e2 = fold_build2 (PLUS_EXPR, TREE_TYPE (vtbl), vtbl, idx);
2363       e2 = build_indirect_ref (e2, NULL);
2364       TREE_CONSTANT (e2) = 1;
2365       TREE_INVARIANT (e2) = 1;
2366
2367       /* When using function descriptors, the address of the
2368          vtable entry is treated as a function pointer.  */
2369       if (TARGET_VTABLE_USES_DESCRIPTORS)
2370         e2 = build1 (NOP_EXPR, TREE_TYPE (e2),
2371                      build_unary_op (ADDR_EXPR, e2, /*noconvert=*/1));
2372
2373       TREE_TYPE (e2) = TREE_TYPE (e3);
2374       e1 = build_conditional_expr (e1, e2, e3);
2375
2376       /* Make sure this doesn't get evaluated first inside one of the
2377          branches of the COND_EXPR.  */
2378       if (instance_save_expr)
2379         e1 = build2 (COMPOUND_EXPR, TREE_TYPE (e1),
2380                      instance_save_expr, e1);
2381
2382       function = e1;
2383     }
2384   return function;
2385 }
2386
2387 tree
2388 build_function_call (tree function, tree params)
2389 {
2390   tree fntype, fndecl;
2391   tree coerced_params;
2392   tree name = NULL_TREE;
2393   int is_method;
2394   tree original = function;
2395
2396   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
2397      Strip such NOP_EXPRs, since FUNCTION is used in non-lvalue context.  */
2398   if (TREE_CODE (function) == NOP_EXPR
2399       && TREE_TYPE (function) == TREE_TYPE (TREE_OPERAND (function, 0)))
2400     function = TREE_OPERAND (function, 0);
2401
2402   if (TREE_CODE (function) == FUNCTION_DECL)
2403     {
2404       name = DECL_NAME (function);
2405
2406       mark_used (function);
2407       fndecl = function;
2408
2409       /* Convert anything with function type to a pointer-to-function.  */
2410       if (pedantic && DECL_MAIN_P (function))
2411         pedwarn ("ISO C++ forbids calling %<::main%> from within program");
2412
2413       /* Differs from default_conversion by not setting TREE_ADDRESSABLE
2414          (because calling an inline function does not mean the function
2415          needs to be separately compiled).  */
2416
2417       if (DECL_INLINE (function))
2418         function = inline_conversion (function);
2419       else
2420         function = build_addr_func (function);
2421     }
2422   else
2423     {
2424       fndecl = NULL_TREE;
2425
2426       function = build_addr_func (function);
2427     }
2428
2429   if (function == error_mark_node)
2430     return error_mark_node;
2431
2432   fntype = TREE_TYPE (function);
2433
2434   if (TYPE_PTRMEMFUNC_P (fntype))
2435     {
2436       error ("must use %<.*%> or %<->*%> to call pointer-to-member "
2437              "function in %<%E (...)%>",
2438              original);
2439       return error_mark_node;
2440     }
2441
2442   is_method = (TREE_CODE (fntype) == POINTER_TYPE
2443                && TREE_CODE (TREE_TYPE (fntype)) == METHOD_TYPE);
2444
2445   if (!((TREE_CODE (fntype) == POINTER_TYPE
2446          && TREE_CODE (TREE_TYPE (fntype)) == FUNCTION_TYPE)
2447         || is_method
2448         || TREE_CODE (function) == TEMPLATE_ID_EXPR))
2449     {
2450       error ("%qE cannot be used as a function", original);
2451       return error_mark_node;
2452     }
2453
2454   /* fntype now gets the type of function pointed to.  */
2455   fntype = TREE_TYPE (fntype);
2456
2457   /* Convert the parameters to the types declared in the
2458      function prototype, or apply default promotions.  */
2459
2460   coerced_params = convert_arguments (TYPE_ARG_TYPES (fntype),
2461                                       params, fndecl, LOOKUP_NORMAL);
2462   if (coerced_params == error_mark_node)
2463     return error_mark_node;
2464
2465   /* Check for errors in format strings and inappropriately
2466      null parameters.  */
2467
2468   check_function_arguments (TYPE_ATTRIBUTES (fntype), coerced_params);
2469
2470   return build_cxx_call (function, coerced_params);
2471 }
2472 \f
2473 /* Convert the actual parameter expressions in the list VALUES
2474    to the types in the list TYPELIST.
2475    If parmdecls is exhausted, or when an element has NULL as its type,
2476    perform the default conversions.
2477
2478    NAME is an IDENTIFIER_NODE or 0.  It is used only for error messages.
2479
2480    This is also where warnings about wrong number of args are generated.
2481
2482    Return a list of expressions for the parameters as converted.
2483
2484    Both VALUES and the returned value are chains of TREE_LIST nodes
2485    with the elements of the list in the TREE_VALUE slots of those nodes.
2486
2487    In C++, unspecified trailing parameters can be filled in with their
2488    default arguments, if such were specified.  Do so here.  */
2489
2490 static tree
2491 convert_arguments (tree typelist, tree values, tree fndecl, int flags)
2492 {
2493   tree typetail, valtail;
2494   tree result = NULL_TREE;
2495   const char *called_thing = 0;
2496   int i = 0;
2497
2498   /* Argument passing is always copy-initialization.  */
2499   flags |= LOOKUP_ONLYCONVERTING;
2500
2501   if (fndecl)
2502     {
2503       if (TREE_CODE (TREE_TYPE (fndecl)) == METHOD_TYPE)
2504         {
2505           if (DECL_NAME (fndecl) == NULL_TREE
2506               || IDENTIFIER_HAS_TYPE_VALUE (DECL_NAME (fndecl)))
2507             called_thing = "constructor";
2508           else
2509             called_thing = "member function";
2510         }
2511       else
2512         called_thing = "function";
2513     }
2514
2515   for (valtail = values, typetail = typelist;
2516        valtail;
2517        valtail = TREE_CHAIN (valtail), i++)
2518     {
2519       tree type = typetail ? TREE_VALUE (typetail) : 0;
2520       tree val = TREE_VALUE (valtail);
2521
2522       if (val == error_mark_node)
2523         return error_mark_node;
2524
2525       if (type == void_type_node)
2526         {
2527           if (fndecl)
2528             {
2529               cp_error_at ("too many arguments to %s %q+#D", called_thing,
2530                            fndecl);
2531               error ("at this point in file");
2532             }
2533           else
2534             error ("too many arguments to function");
2535           /* In case anybody wants to know if this argument
2536              list is valid.  */
2537           if (result)
2538             TREE_TYPE (tree_last (result)) = error_mark_node;
2539           break;
2540         }
2541
2542       /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
2543          Strip such NOP_EXPRs, since VAL is used in non-lvalue context.  */
2544       if (TREE_CODE (val) == NOP_EXPR
2545           && TREE_TYPE (val) == TREE_TYPE (TREE_OPERAND (val, 0))
2546           && (type == 0 || TREE_CODE (type) != REFERENCE_TYPE))
2547         val = TREE_OPERAND (val, 0);
2548
2549       if (type == 0 || TREE_CODE (type) != REFERENCE_TYPE)
2550         {
2551           if (TREE_CODE (TREE_TYPE (val)) == ARRAY_TYPE
2552               || TREE_CODE (TREE_TYPE (val)) == FUNCTION_TYPE
2553               || TREE_CODE (TREE_TYPE (val)) == METHOD_TYPE)
2554             val = decay_conversion (val);
2555         }
2556
2557       if (val == error_mark_node)
2558         return error_mark_node;
2559
2560       if (type != 0)
2561         {
2562           /* Formal parm type is specified by a function prototype.  */
2563           tree parmval;
2564
2565           if (!COMPLETE_TYPE_P (complete_type (type)))
2566             {
2567               if (fndecl)
2568                 error ("parameter %P of %qD has incomplete type %qT",
2569                        i, fndecl, type);
2570               else
2571                 error ("parameter %P has incomplete type %qT", i, type);
2572               parmval = error_mark_node;
2573             }
2574           else
2575             {
2576               parmval = convert_for_initialization
2577                 (NULL_TREE, type, val, flags,
2578                  "argument passing", fndecl, i);
2579               parmval = convert_for_arg_passing (type, parmval);
2580             }
2581
2582           if (parmval == error_mark_node)
2583             return error_mark_node;
2584
2585           result = tree_cons (NULL_TREE, parmval, result);
2586         }
2587       else
2588         {
2589           if (fndecl && DECL_BUILT_IN (fndecl)
2590               && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_CONSTANT_P)
2591             /* Don't do ellipsis conversion for __built_in_constant_p
2592                as this will result in spurious warnings for non-POD
2593                types.  */
2594             val = require_complete_type (val);
2595           else
2596             val = convert_arg_to_ellipsis (val);
2597
2598           result = tree_cons (NULL_TREE, val, result);
2599         }
2600
2601       if (typetail)
2602         typetail = TREE_CHAIN (typetail);
2603     }
2604
2605   if (typetail != 0 && typetail != void_list_node)
2606     {
2607       /* See if there are default arguments that can be used.  */
2608       if (TREE_PURPOSE (typetail)
2609           && TREE_CODE (TREE_PURPOSE (typetail)) != DEFAULT_ARG)
2610         {
2611           for (; typetail != void_list_node; ++i)
2612             {
2613               tree parmval
2614                 = convert_default_arg (TREE_VALUE (typetail),
2615                                        TREE_PURPOSE (typetail),
2616                                        fndecl, i);
2617
2618               if (parmval == error_mark_node)
2619                 return error_mark_node;
2620
2621               result = tree_cons (0, parmval, result);
2622               typetail = TREE_CHAIN (typetail);
2623               /* ends with `...'.  */
2624               if (typetail == NULL_TREE)
2625                 break;
2626             }
2627         }
2628       else
2629         {
2630           if (fndecl)
2631             {
2632               cp_error_at ("too few arguments to %s %q+#D",
2633                            called_thing, fndecl);
2634               error ("at this point in file");
2635             }
2636           else
2637             error ("too few arguments to function");
2638           return error_mark_list;
2639         }
2640     }
2641
2642   return nreverse (result);
2643 }
2644 \f
2645 /* Build a binary-operation expression, after performing default
2646    conversions on the operands.  CODE is the kind of expression to build.  */
2647
2648 tree
2649 build_x_binary_op (enum tree_code code, tree arg1, tree arg2,
2650                    bool *overloaded_p)
2651 {
2652   tree orig_arg1;
2653   tree orig_arg2;
2654   tree expr;
2655
2656   orig_arg1 = arg1;
2657   orig_arg2 = arg2;
2658
2659   if (processing_template_decl)
2660     {
2661       if (type_dependent_expression_p (arg1)
2662           || type_dependent_expression_p (arg2))
2663         return build_min_nt (code, arg1, arg2);
2664       arg1 = build_non_dependent_expr (arg1);
2665       arg2 = build_non_dependent_expr (arg2);
2666     }
2667
2668   if (code == DOTSTAR_EXPR)
2669     expr = build_m_component_ref (arg1, arg2);
2670   else
2671     expr = build_new_op (code, LOOKUP_NORMAL, arg1, arg2, NULL_TREE,
2672                          overloaded_p);
2673
2674   if (processing_template_decl && expr != error_mark_node)
2675     return build_min_non_dep (code, expr, orig_arg1, orig_arg2);
2676
2677   return expr;
2678 }
2679
2680 /* Build a binary-operation expression without default conversions.
2681    CODE is the kind of expression to build.
2682    This function differs from `build' in several ways:
2683    the data type of the result is computed and recorded in it,
2684    warnings are generated if arg data types are invalid,
2685    special handling for addition and subtraction of pointers is known,
2686    and some optimization is done (operations on narrow ints
2687    are done in the narrower type when that gives the same result).
2688    Constant folding is also done before the result is returned.
2689
2690    Note that the operands will never have enumeral types
2691    because either they have just had the default conversions performed
2692    or they have both just been converted to some other type in which
2693    the arithmetic is to be done.
2694
2695    C++: must do special pointer arithmetic when implementing
2696    multiple inheritance, and deal with pointer to member functions.  */
2697
2698 tree
2699 build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
2700                  int convert_p ATTRIBUTE_UNUSED)
2701 {
2702   tree op0, op1;
2703   enum tree_code code0, code1;
2704   tree type0, type1;
2705
2706   /* Expression code to give to the expression when it is built.
2707      Normally this is CODE, which is what the caller asked for,
2708      but in some special cases we change it.  */
2709   enum tree_code resultcode = code;
2710
2711   /* Data type in which the computation is to be performed.
2712      In the simplest cases this is the common type of the arguments.  */
2713   tree result_type = NULL;
2714
2715   /* Nonzero means operands have already been type-converted
2716      in whatever way is necessary.
2717      Zero means they need to be converted to RESULT_TYPE.  */
2718   int converted = 0;
2719
2720   /* Nonzero means create the expression with this type, rather than
2721      RESULT_TYPE.  */
2722   tree build_type = 0;
2723
2724   /* Nonzero means after finally constructing the expression
2725      convert it to this type.  */
2726   tree final_type = 0;
2727
2728   tree result;
2729
2730   /* Nonzero if this is an operation like MIN or MAX which can
2731      safely be computed in short if both args are promoted shorts.
2732      Also implies COMMON.
2733      -1 indicates a bitwise operation; this makes a difference
2734      in the exact conditions for when it is safe to do the operation
2735      in a narrower mode.  */
2736   int shorten = 0;
2737
2738   /* Nonzero if this is a comparison operation;
2739      if both args are promoted shorts, compare the original shorts.
2740      Also implies COMMON.  */
2741   int short_compare = 0;
2742
2743   /* Nonzero if this is a right-shift operation, which can be computed on the
2744      original short and then promoted if the operand is a promoted short.  */
2745   int short_shift = 0;
2746
2747   /* Nonzero means set RESULT_TYPE to the common type of the args.  */
2748   int common = 0;
2749
2750   /* True if both operands have arithmetic type.  */
2751   bool arithmetic_types_p;
2752
2753   /* Apply default conversions.  */
2754   op0 = orig_op0;
2755   op1 = orig_op1;
2756
2757   if (code == TRUTH_AND_EXPR || code == TRUTH_ANDIF_EXPR
2758       || code == TRUTH_OR_EXPR || code == TRUTH_ORIF_EXPR
2759       || code == TRUTH_XOR_EXPR)
2760     {
2761       if (!really_overloaded_fn (op0))
2762         op0 = decay_conversion (op0);
2763       if (!really_overloaded_fn (op1))
2764         op1 = decay_conversion (op1);
2765     }
2766   else
2767     {
2768       if (!really_overloaded_fn (op0))
2769         op0 = default_conversion (op0);
2770       if (!really_overloaded_fn (op1))
2771         op1 = default_conversion (op1);
2772     }
2773
2774   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
2775   STRIP_TYPE_NOPS (op0);
2776   STRIP_TYPE_NOPS (op1);
2777
2778   /* DTRT if one side is an overloaded function, but complain about it.  */
2779   if (type_unknown_p (op0))
2780     {
2781       tree t = instantiate_type (TREE_TYPE (op1), op0, tf_none);
2782       if (t != error_mark_node)
2783         {
2784           pedwarn ("assuming cast to type %qT from overloaded function",
2785                    TREE_TYPE (t));
2786           op0 = t;
2787         }
2788     }
2789   if (type_unknown_p (op1))
2790     {
2791       tree t = instantiate_type (TREE_TYPE (op0), op1, tf_none);
2792       if (t != error_mark_node)
2793         {
2794           pedwarn ("assuming cast to type %qT from overloaded function",
2795                    TREE_TYPE (t));
2796           op1 = t;
2797         }
2798     }
2799
2800   type0 = TREE_TYPE (op0);
2801   type1 = TREE_TYPE (op1);
2802
2803   /* The expression codes of the data types of the arguments tell us
2804      whether the arguments are integers, floating, pointers, etc.  */
2805   code0 = TREE_CODE (type0);
2806   code1 = TREE_CODE (type1);
2807
2808   /* If an error was already reported for one of the arguments,
2809      avoid reporting another error.  */
2810
2811   if (code0 == ERROR_MARK || code1 == ERROR_MARK)
2812     return error_mark_node;
2813
2814   switch (code)
2815     {
2816     case PLUS_EXPR:
2817       /* Handle the pointer + int case.  */
2818       if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
2819         return cp_pointer_int_sum (PLUS_EXPR, op0, op1);
2820       else if (code1 == POINTER_TYPE && code0 == INTEGER_TYPE)
2821         return cp_pointer_int_sum (PLUS_EXPR, op1, op0);
2822       else
2823         common = 1;
2824       break;
2825
2826     case MINUS_EXPR:
2827       /* Subtraction of two similar pointers.
2828          We must subtract them as integers, then divide by object size.  */
2829       if (code0 == POINTER_TYPE && code1 == POINTER_TYPE
2830           && same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (type0),
2831                                                         TREE_TYPE (type1)))
2832         return pointer_diff (op0, op1, common_type (type0, type1));
2833       /* Handle pointer minus int.  Just like pointer plus int.  */
2834       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
2835         return cp_pointer_int_sum (MINUS_EXPR, op0, op1);
2836       else
2837         common = 1;
2838       break;
2839
2840     case MULT_EXPR:
2841       common = 1;
2842       break;
2843
2844     case TRUNC_DIV_EXPR:
2845     case CEIL_DIV_EXPR:
2846     case FLOOR_DIV_EXPR:
2847     case ROUND_DIV_EXPR:
2848     case EXACT_DIV_EXPR:
2849       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
2850            || code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
2851           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
2852               || code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE))
2853         {
2854           if (TREE_CODE (op1) == INTEGER_CST && integer_zerop (op1))
2855             warning ("division by zero in %<%E / 0%>", op0);
2856           else if (TREE_CODE (op1) == REAL_CST && real_zerop (op1))
2857             warning ("division by zero in %<%E / 0.%>", op0);
2858
2859           if (code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
2860             code0 = TREE_CODE (TREE_TYPE (TREE_TYPE (op0)));
2861           if (code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE)
2862             code1 = TREE_CODE (TREE_TYPE (TREE_TYPE (op1)));
2863
2864           if (!(code0 == INTEGER_TYPE && code1 == INTEGER_TYPE))
2865             resultcode = RDIV_EXPR;
2866           else
2867             /* When dividing two signed integers, we have to promote to int.
2868                unless we divide by a constant != -1.  Note that default
2869                conversion will have been performed on the operands at this
2870                point, so we have to dig out the original type to find out if
2871                it was unsigned.  */
2872             shorten = ((TREE_CODE (op0) == NOP_EXPR
2873                         && TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op0, 0))))
2874                        || (TREE_CODE (op1) == INTEGER_CST
2875                            && ! integer_all_onesp (op1)));
2876
2877           common = 1;
2878         }
2879       break;
2880
2881     case BIT_AND_EXPR:
2882     case BIT_IOR_EXPR:
2883     case BIT_XOR_EXPR:
2884       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2885         shorten = -1;
2886       break;
2887
2888     case TRUNC_MOD_EXPR:
2889     case FLOOR_MOD_EXPR:
2890       if (code1 == INTEGER_TYPE && integer_zerop (op1))
2891         warning ("division by zero in %<%E %% 0%>", op0);
2892       else if (code1 == REAL_TYPE && real_zerop (op1))
2893         warning ("division by zero in %<%E %% 0.%>", op0);
2894
2895       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2896         {
2897           /* Although it would be tempting to shorten always here, that loses
2898              on some targets, since the modulo instruction is undefined if the
2899              quotient can't be represented in the computation mode.  We shorten
2900              only if unsigned or if dividing by something we know != -1.  */
2901           shorten = ((TREE_CODE (op0) == NOP_EXPR
2902                       && TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op0, 0))))
2903                      || (TREE_CODE (op1) == INTEGER_CST
2904                          && ! integer_all_onesp (op1)));
2905           common = 1;
2906         }
2907       break;
2908
2909     case TRUTH_ANDIF_EXPR:
2910     case TRUTH_ORIF_EXPR:
2911     case TRUTH_AND_EXPR:
2912     case TRUTH_OR_EXPR:
2913       result_type = boolean_type_node;
2914       break;
2915
2916       /* Shift operations: result has same type as first operand;
2917          always convert second operand to int.
2918          Also set SHORT_SHIFT if shifting rightward.  */
2919
2920     case RSHIFT_EXPR:
2921       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2922         {
2923           result_type = type0;
2924           if (TREE_CODE (op1) == INTEGER_CST)
2925             {
2926               if (tree_int_cst_lt (op1, integer_zero_node))
2927                 warning ("right shift count is negative");
2928               else
2929                 {
2930                   if (! integer_zerop (op1))
2931                     short_shift = 1;
2932                   if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
2933                     warning ("right shift count >= width of type");
2934                 }
2935             }
2936           /* Convert the shift-count to an integer, regardless of
2937              size of value being shifted.  */
2938           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
2939             op1 = cp_convert (integer_type_node, op1);
2940           /* Avoid converting op1 to result_type later.  */
2941           converted = 1;
2942         }
2943       break;
2944
2945     case LSHIFT_EXPR:
2946       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2947         {
2948           result_type = type0;
2949           if (TREE_CODE (op1) == INTEGER_CST)
2950             {
2951               if (tree_int_cst_lt (op1, integer_zero_node))
2952                 warning ("left shift count is negative");
2953               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
2954                 warning ("left shift count >= width of type");
2955             }
2956           /* Convert the shift-count to an integer, regardless of
2957              size of value being shifted.  */
2958           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
2959             op1 = cp_convert (integer_type_node, op1);
2960           /* Avoid converting op1 to result_type later.  */
2961           converted = 1;
2962         }
2963       break;
2964
2965     case RROTATE_EXPR:
2966     case LROTATE_EXPR:
2967       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2968         {
2969           result_type = type0;
2970           if (TREE_CODE (op1) == INTEGER_CST)
2971             {
2972               if (tree_int_cst_lt (op1, integer_zero_node))
2973                 warning ("%s rotate count is negative",
2974                          (code == LROTATE_EXPR) ? "left" : "right");
2975               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
2976                 warning ("%s rotate count >= width of type",
2977                          (code == LROTATE_EXPR) ? "left" : "right");
2978             }
2979           /* Convert the shift-count to an integer, regardless of
2980              size of value being shifted.  */
2981           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
2982             op1 = cp_convert (integer_type_node, op1);
2983         }
2984       break;
2985
2986     case EQ_EXPR:
2987     case NE_EXPR:
2988       if (warn_float_equal && (code0 == REAL_TYPE || code1 == REAL_TYPE))
2989         warning ("comparing floating point with == or != is unsafe");
2990
2991       build_type = boolean_type_node;
2992       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
2993            || code0 == COMPLEX_TYPE)
2994           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
2995               || code1 == COMPLEX_TYPE))
2996         short_compare = 1;
2997       else if ((code0 == POINTER_TYPE && code1 == POINTER_TYPE)
2998                || (TYPE_PTRMEM_P (type0) && TYPE_PTRMEM_P (type1)))
2999         result_type = composite_pointer_type (type0, type1, op0, op1,
3000                                               "comparison");
3001       else if ((code0 == POINTER_TYPE || TYPE_PTRMEM_P (type0))
3002                && null_ptr_cst_p (op1))
3003         result_type = type0;
3004       else if ((code1 == POINTER_TYPE || TYPE_PTRMEM_P (type1))
3005                && null_ptr_cst_p (op0))
3006         result_type = type1;
3007       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
3008         {
3009           result_type = type0;
3010           error ("ISO C++ forbids comparison between pointer and integer");
3011         }
3012       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
3013         {
3014           result_type = type1;
3015           error ("ISO C++ forbids comparison between pointer and integer");
3016         }
3017       else if (TYPE_PTRMEMFUNC_P (type0) && null_ptr_cst_p (op1))
3018         {
3019           op0 = build_ptrmemfunc_access_expr (op0, pfn_identifier);
3020           op1 = cp_convert (TREE_TYPE (op0), integer_zero_node);
3021           result_type = TREE_TYPE (op0);
3022         }
3023       else if (TYPE_PTRMEMFUNC_P (type1) && null_ptr_cst_p (op0))
3024         return cp_build_binary_op (code, op1, op0);
3025       else if (TYPE_PTRMEMFUNC_P (type0) && TYPE_PTRMEMFUNC_P (type1)
3026                && same_type_p (type0, type1))
3027         {
3028           /* E will be the final comparison.  */
3029           tree e;
3030           /* E1 and E2 are for scratch.  */
3031           tree e1;
3032           tree e2;
3033           tree pfn0;
3034           tree pfn1;
3035           tree delta0;
3036           tree delta1;
3037
3038           if (TREE_SIDE_EFFECTS (op0))
3039             op0 = save_expr (op0);
3040           if (TREE_SIDE_EFFECTS (op1))
3041             op1 = save_expr (op1);
3042
3043           /* We generate:
3044
3045              (op0.pfn == op1.pfn
3046               && (!op0.pfn || op0.delta == op1.delta))
3047
3048              The reason for the `!op0.pfn' bit is that a NULL
3049              pointer-to-member is any member with a zero PFN; the
3050              DELTA field is unspecified.  */
3051           pfn0 = pfn_from_ptrmemfunc (op0);
3052           pfn1 = pfn_from_ptrmemfunc (op1);
3053           delta0 = build_ptrmemfunc_access_expr (op0,
3054                                                  delta_identifier);
3055           delta1 = build_ptrmemfunc_access_expr (op1,
3056                                                  delta_identifier);
3057           e1 = cp_build_binary_op (EQ_EXPR, delta0, delta1);
3058           e2 = cp_build_binary_op (EQ_EXPR,
3059                                    pfn0,
3060                                    cp_convert (TREE_TYPE (pfn0),
3061                                                integer_zero_node));
3062           e1 = cp_build_binary_op (TRUTH_ORIF_EXPR, e1, e2);
3063           e2 = build2 (EQ_EXPR, boolean_type_node, pfn0, pfn1);
3064           e = cp_build_binary_op (TRUTH_ANDIF_EXPR, e2, e1);
3065           if (code == EQ_EXPR)
3066             return e;
3067           return cp_build_binary_op (EQ_EXPR, e, integer_zero_node);
3068         }
3069       else
3070         {
3071           gcc_assert (!TYPE_PTRMEMFUNC_P (type0)
3072                       || !same_type_p (TYPE_PTRMEMFUNC_FN_TYPE (type0),
3073                                        type1));
3074           gcc_assert (!TYPE_PTRMEMFUNC_P (type1)
3075                       || !same_type_p (TYPE_PTRMEMFUNC_FN_TYPE (type1),
3076                                        type0));
3077         }
3078
3079       break;
3080
3081     case MAX_EXPR:
3082     case MIN_EXPR:
3083       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
3084            && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
3085         shorten = 1;
3086       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
3087         result_type = composite_pointer_type (type0, type1, op0, op1,
3088                                               "comparison");
3089       break;
3090
3091     case LE_EXPR:
3092     case GE_EXPR:
3093     case LT_EXPR:
3094     case GT_EXPR:
3095       build_type = boolean_type_node;
3096       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
3097            && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
3098         short_compare = 1;
3099       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
3100         result_type = composite_pointer_type (type0, type1, op0, op1,
3101                                               "comparison");
3102       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
3103                && integer_zerop (op1))
3104         result_type = type0;
3105       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
3106                && integer_zerop (op0))
3107         result_type = type1;
3108       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
3109         {
3110           result_type = type0;
3111           pedwarn ("ISO C++ forbids comparison between pointer and integer");
3112         }
3113       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
3114         {
3115           result_type = type1;
3116           pedwarn ("ISO C++ forbids comparison between pointer and integer");
3117         }
3118       break;
3119
3120     case UNORDERED_EXPR:
3121     case ORDERED_EXPR:
3122     case UNLT_EXPR:
3123     case UNLE_EXPR:
3124     case UNGT_EXPR:
3125     case UNGE_EXPR:
3126     case UNEQ_EXPR:
3127       build_type = integer_type_node;
3128       if (code0 != REAL_TYPE || code1 != REAL_TYPE)
3129         {
3130           error ("unordered comparison on non-floating point argument");
3131           return error_mark_node;
3132         }
3133       common = 1;
3134       break;
3135
3136     default:
3137       break;
3138     }
3139
3140   arithmetic_types_p =
3141     ((code0 == INTEGER_TYPE || code0 == REAL_TYPE || code0 == COMPLEX_TYPE)
3142      && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
3143          || code1 == COMPLEX_TYPE));
3144   /* Determine the RESULT_TYPE, if it is not already known.  */
3145   if (!result_type
3146       && arithmetic_types_p
3147       && (shorten || common || short_compare))
3148     result_type = common_type (type0, type1);
3149
3150   if (!result_type)
3151     {
3152       error ("invalid operands of types %qT and %qT to binary %qO",
3153              TREE_TYPE (orig_op0), TREE_TYPE (orig_op1), code);
3154       return error_mark_node;
3155     }
3156
3157   /* If we're in a template, the only thing we need to know is the
3158      RESULT_TYPE.  */
3159   if (processing_template_decl)
3160     return build2 (resultcode,
3161                    build_type ? build_type : result_type,
3162                    op0, op1);
3163
3164   if (arithmetic_types_p)
3165     {
3166       int none_complex = (code0 != COMPLEX_TYPE && code1 != COMPLEX_TYPE);
3167
3168       /* For certain operations (which identify themselves by shorten != 0)
3169          if both args were extended from the same smaller type,
3170          do the arithmetic in that type and then extend.
3171
3172          shorten !=0 and !=1 indicates a bitwise operation.
3173          For them, this optimization is safe only if
3174          both args are zero-extended or both are sign-extended.
3175          Otherwise, we might change the result.
3176          Eg, (short)-1 | (unsigned short)-1 is (int)-1
3177          but calculated in (unsigned short) it would be (unsigned short)-1.  */
3178
3179       if (shorten && none_complex)
3180         {
3181           int unsigned0, unsigned1;
3182           tree arg0 = get_narrower (op0, &unsigned0);
3183           tree arg1 = get_narrower (op1, &unsigned1);
3184           /* UNS is 1 if the operation to be done is an unsigned one.  */
3185           int uns = TYPE_UNSIGNED (result_type);
3186           tree type;
3187
3188           final_type = result_type;
3189
3190           /* Handle the case that OP0 does not *contain* a conversion
3191              but it *requires* conversion to FINAL_TYPE.  */
3192
3193           if (op0 == arg0 && TREE_TYPE (op0) != final_type)
3194             unsigned0 = TYPE_UNSIGNED (TREE_TYPE (op0));
3195           if (op1 == arg1 && TREE_TYPE (op1) != final_type)
3196             unsigned1 = TYPE_UNSIGNED (TREE_TYPE (op1));
3197
3198           /* Now UNSIGNED0 is 1 if ARG0 zero-extends to FINAL_TYPE.  */
3199
3200           /* For bitwise operations, signedness of nominal type
3201              does not matter.  Consider only how operands were extended.  */
3202           if (shorten == -1)
3203             uns = unsigned0;
3204
3205           /* Note that in all three cases below we refrain from optimizing
3206              an unsigned operation on sign-extended args.
3207              That would not be valid.  */
3208
3209           /* Both args variable: if both extended in same way
3210              from same width, do it in that width.
3211              Do it unsigned if args were zero-extended.  */
3212           if ((TYPE_PRECISION (TREE_TYPE (arg0))
3213                < TYPE_PRECISION (result_type))
3214               && (TYPE_PRECISION (TREE_TYPE (arg1))
3215                   == TYPE_PRECISION (TREE_TYPE (arg0)))
3216               && unsigned0 == unsigned1
3217               && (unsigned0 || !uns))
3218             result_type = c_common_signed_or_unsigned_type
3219               (unsigned0, common_type (TREE_TYPE (arg0), TREE_TYPE (arg1)));
3220           else if (TREE_CODE (arg0) == INTEGER_CST
3221                    && (unsigned1 || !uns)
3222                    && (TYPE_PRECISION (TREE_TYPE (arg1))
3223                        < TYPE_PRECISION (result_type))
3224                    && (type = c_common_signed_or_unsigned_type
3225                        (unsigned1, TREE_TYPE (arg1)),
3226                        int_fits_type_p (arg0, type)))
3227             result_type = type;
3228           else if (TREE_CODE (arg1) == INTEGER_CST
3229                    && (unsigned0 || !uns)
3230                    && (TYPE_PRECISION (TREE_TYPE (arg0))
3231                        < TYPE_PRECISION (result_type))
3232                    && (type = c_common_signed_or_unsigned_type
3233                        (unsigned0, TREE_TYPE (arg0)),
3234                        int_fits_type_p (arg1, type)))
3235             result_type = type;
3236         }
3237
3238       /* Shifts can be shortened if shifting right.  */
3239
3240       if (short_shift)
3241         {
3242           int unsigned_arg;
3243           tree arg0 = get_narrower (op0, &unsigned_arg);
3244
3245           final_type = result_type;
3246
3247           if (arg0 == op0 && final_type == TREE_TYPE (op0))
3248             unsigned_arg = TYPE_UNSIGNED (TREE_TYPE (op0));
3249
3250           if (TYPE_PRECISION (TREE_TYPE (arg0)) < TYPE_PRECISION (result_type)
3251               /* We can shorten only if the shift count is less than the
3252                  number of bits in the smaller type size.  */
3253               && compare_tree_int (op1, TYPE_PRECISION (TREE_TYPE (arg0))) < 0
3254               /* If arg is sign-extended and then unsigned-shifted,
3255                  we can simulate this with a signed shift in arg's type
3256                  only if the extended result is at least twice as wide
3257                  as the arg.  Otherwise, the shift could use up all the
3258                  ones made by sign-extension and bring in zeros.
3259                  We can't optimize that case at all, but in most machines
3260                  it never happens because available widths are 2**N.  */
3261               && (!TYPE_UNSIGNED (final_type)
3262                   || unsigned_arg
3263                   || (((unsigned) 2 * TYPE_PRECISION (TREE_TYPE (arg0)))
3264                       <= TYPE_PRECISION (result_type))))
3265             {
3266               /* Do an unsigned shift if the operand was zero-extended.  */
3267               result_type
3268                 = c_common_signed_or_unsigned_type (unsigned_arg,
3269                                                     TREE_TYPE (arg0));
3270               /* Convert value-to-be-shifted to that type.  */
3271               if (TREE_TYPE (op0) != result_type)
3272                 op0 = cp_convert (result_type, op0);
3273               converted = 1;
3274             }
3275         }
3276
3277       /* Comparison operations are shortened too but differently.
3278          They identify themselves by setting short_compare = 1.  */
3279
3280       if (short_compare)
3281         {
3282           /* Don't write &op0, etc., because that would prevent op0
3283              from being kept in a register.
3284              Instead, make copies of the our local variables and
3285              pass the copies by reference, then copy them back afterward.  */
3286           tree xop0 = op0, xop1 = op1, xresult_type = result_type;
3287           enum tree_code xresultcode = resultcode;
3288           tree val
3289             = shorten_compare (&xop0, &xop1, &xresult_type, &xresultcode);
3290           if (val != 0)
3291             return cp_convert (boolean_type_node, val);
3292           op0 = xop0, op1 = xop1;
3293           converted = 1;
3294           resultcode = xresultcode;
3295         }
3296
3297       if ((short_compare || code == MIN_EXPR || code == MAX_EXPR)
3298           && warn_sign_compare
3299           /* Do not warn until the template is instantiated; we cannot
3300              bound the ranges of the arguments until that point.  */
3301           && !processing_template_decl)
3302         {
3303           int op0_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op0));
3304           int op1_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op1));
3305
3306           int unsignedp0, unsignedp1;
3307           tree primop0 = get_narrower (op0, &unsignedp0);
3308           tree primop1 = get_narrower (op1, &unsignedp1);
3309
3310           /* Check for comparison of different enum types.  */
3311           if (TREE_CODE (TREE_TYPE (orig_op0)) == ENUMERAL_TYPE
3312               && TREE_CODE (TREE_TYPE (orig_op1)) == ENUMERAL_TYPE
3313               && TYPE_MAIN_VARIANT (TREE_TYPE (orig_op0))
3314                  != TYPE_MAIN_VARIANT (TREE_TYPE (orig_op1)))
3315             {
3316               warning ("comparison between types %q#T and %q#T",
3317                        TREE_TYPE (orig_op0), TREE_TYPE (orig_op1));
3318             }
3319
3320           /* Give warnings for comparisons between signed and unsigned
3321              quantities that may fail.  */
3322           /* Do the checking based on the original operand trees, so that
3323              casts will be considered, but default promotions won't be.  */
3324
3325           /* Do not warn if the comparison is being done in a signed type,
3326              since the signed type will only be chosen if it can represent
3327              all the values of the unsigned type.  */
3328           if (!TYPE_UNSIGNED (result_type))
3329             /* OK */;
3330           /* Do not warn if both operands are unsigned.  */
3331           else if (op0_signed == op1_signed)
3332             /* OK */;
3333           /* Do not warn if the signed quantity is an unsuffixed
3334              integer literal (or some static constant expression
3335              involving such literals or a conditional expression
3336              involving such literals) and it is non-negative.  */
3337           else if ((op0_signed && tree_expr_nonnegative_p (orig_op0))
3338                    || (op1_signed && tree_expr_nonnegative_p (orig_op1)))
3339             /* OK */;
3340           /* Do not warn if the comparison is an equality operation,
3341              the unsigned quantity is an integral constant and it does
3342              not use the most significant bit of result_type.  */
3343           else if ((resultcode == EQ_EXPR || resultcode == NE_EXPR)
3344                    && ((op0_signed && TREE_CODE (orig_op1) == INTEGER_CST
3345                         && int_fits_type_p (orig_op1, c_common_signed_type
3346                                             (result_type)))
3347                         || (op1_signed && TREE_CODE (orig_op0) == INTEGER_CST
3348                             && int_fits_type_p (orig_op0, c_common_signed_type
3349                                                 (result_type)))))
3350             /* OK */;
3351           else
3352             warning ("comparison between signed and unsigned integer expressions");
3353
3354           /* Warn if two unsigned values are being compared in a size
3355              larger than their original size, and one (and only one) is the
3356              result of a `~' operator.  This comparison will always fail.
3357
3358              Also warn if one operand is a constant, and the constant does not
3359              have all bits set that are set in the ~ operand when it is
3360              extended.  */
3361
3362           if ((TREE_CODE (primop0) == BIT_NOT_EXPR)
3363               ^ (TREE_CODE (primop1) == BIT_NOT_EXPR))
3364             {
3365               if (TREE_CODE (primop0) == BIT_NOT_EXPR)
3366                 primop0 = get_narrower (TREE_OPERAND (op0, 0), &unsignedp0);
3367               if (TREE_CODE (primop1) == BIT_NOT_EXPR)
3368                 primop1 = get_narrower (TREE_OPERAND (op1, 0), &unsignedp1);
3369
3370               if (host_integerp (primop0, 0) || host_integerp (primop1, 0))
3371                 {
3372                   tree primop;
3373                   HOST_WIDE_INT constant, mask;
3374                   int unsignedp;
3375                   unsigned int bits;
3376
3377                   if (host_integerp (primop0, 0))
3378                     {
3379                       primop = primop1;
3380                       unsignedp = unsignedp1;
3381                       constant = tree_low_cst (primop0, 0);
3382                     }
3383                   else
3384                     {
3385                       primop = primop0;
3386                       unsignedp = unsignedp0;
3387                       constant = tree_low_cst (primop1, 0);
3388                     }
3389
3390                   bits = TYPE_PRECISION (TREE_TYPE (primop));
3391                   if (bits < TYPE_PRECISION (result_type)
3392                       && bits < HOST_BITS_PER_LONG && unsignedp)
3393                     {
3394                       mask = (~ (HOST_WIDE_INT) 0) << bits;
3395                       if ((mask & constant) != mask)
3396                         warning ("comparison of promoted ~unsigned with constant");
3397                     }
3398                 }
3399               else if (unsignedp0 && unsignedp1
3400                        && (TYPE_PRECISION (TREE_TYPE (primop0))
3401                            < TYPE_PRECISION (result_type))
3402                        && (TYPE_PRECISION (TREE_TYPE (primop1))
3403                            < TYPE_PRECISION (result_type)))
3404                 warning ("comparison of promoted ~unsigned with unsigned");
3405             }
3406         }
3407     }
3408
3409   /* If CONVERTED is zero, both args will be converted to type RESULT_TYPE.
3410      Then the expression will be built.
3411      It will be given type FINAL_TYPE if that is nonzero;
3412      otherwise, it will be given type RESULT_TYPE.  */
3413
3414   /* Issue warnings about peculiar, but valid, uses of NULL.  */
3415   if (/* It's reasonable to use pointer values as operands of &&
3416          and ||, so NULL is no exception.  */
3417       !(code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
3418       && (/* If OP0 is NULL and OP1 is not a pointer, or vice versa.  */
3419           (orig_op0 == null_node
3420            && TREE_CODE (TREE_TYPE (op1)) != POINTER_TYPE)
3421           /* Or vice versa.  */
3422           || (orig_op1 == null_node
3423               && TREE_CODE (TREE_TYPE (op0)) != POINTER_TYPE)
3424           /* Or, both are NULL and the operation was not a comparison.  */
3425           || (orig_op0 == null_node && orig_op1 == null_node
3426               && code != EQ_EXPR && code != NE_EXPR)))
3427     /* Some sort of arithmetic operation involving NULL was
3428        performed.  Note that pointer-difference and pointer-addition
3429        have already been handled above, and so we don't end up here in
3430        that case.  */
3431     warning ("NULL used in arithmetic");
3432
3433   if (! converted)
3434     {
3435       if (TREE_TYPE (op0) != result_type)
3436         op0 = cp_convert (result_type, op0);
3437       if (TREE_TYPE (op1) != result_type)
3438         op1 = cp_convert (result_type, op1);
3439
3440       if (op0 == error_mark_node || op1 == error_mark_node)
3441         return error_mark_node;
3442     }
3443
3444   if (build_type == NULL_TREE)
3445     build_type = result_type;
3446
3447   result = build2 (resultcode, build_type, op0, op1);
3448   result = fold_if_not_in_template (result);
3449   if (final_type != 0)
3450     result = cp_convert (final_type, result);
3451   return result;
3452 }
3453 \f
3454 /* Return a tree for the sum or difference (RESULTCODE says which)
3455    of pointer PTROP and integer INTOP.  */
3456
3457 static tree
3458 cp_pointer_int_sum (enum tree_code resultcode, tree ptrop, tree intop)
3459 {
3460   tree res_type = TREE_TYPE (ptrop);
3461
3462   /* pointer_int_sum() uses size_in_bytes() on the TREE_TYPE(res_type)
3463      in certain circumstance (when it's valid to do so).  So we need
3464      to make sure it's complete.  We don't need to check here, if we
3465      can actually complete it at all, as those checks will be done in
3466      pointer_int_sum() anyway.  */
3467   complete_type (TREE_TYPE (res_type));
3468
3469   return pointer_int_sum (resultcode, ptrop,
3470                           fold_if_not_in_template (intop));
3471 }
3472
3473 /* Return a tree for the difference of pointers OP0 and OP1.
3474    The resulting tree has type int.  */
3475
3476 static tree
3477 pointer_diff (tree op0, tree op1, tree ptrtype)
3478 {
3479   tree result;
3480   tree restype = ptrdiff_type_node;
3481   tree target_type = TREE_TYPE (ptrtype);
3482
3483   if (!complete_type_or_else (target_type, NULL_TREE))
3484     return error_mark_node;
3485
3486   if (pedantic || warn_pointer_arith)
3487     {
3488       if (TREE_CODE (target_type) == VOID_TYPE)
3489         pedwarn ("ISO C++ forbids using pointer of type %<void *%> in subtraction");
3490       if (TREE_CODE (target_type) == FUNCTION_TYPE)
3491         pedwarn ("ISO C++ forbids using pointer to a function in subtraction");
3492       if (TREE_CODE (target_type) == METHOD_TYPE)
3493         pedwarn ("ISO C++ forbids using pointer to a method in subtraction");
3494     }
3495
3496   /* First do the subtraction as integers;
3497      then drop through to build the divide operator.  */
3498
3499   op0 = cp_build_binary_op (MINUS_EXPR,
3500                             cp_convert (restype, op0),
3501                             cp_convert (restype, op1));
3502
3503   /* This generates an error if op1 is a pointer to an incomplete type.  */
3504   if (!COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (op1))))
3505     error ("invalid use of a pointer to an incomplete type in pointer arithmetic");
3506
3507   op1 = (TYPE_PTROB_P (ptrtype)
3508          ? size_in_bytes (target_type)
3509          : integer_one_node);
3510
3511   /* Do the division.  */
3512
3513   result = build2 (EXACT_DIV_EXPR, restype, op0, cp_convert (restype, op1));
3514   return fold_if_not_in_template (result);
3515 }
3516 \f
3517 /* Construct and perhaps optimize a tree representation
3518    for a unary operation.  CODE, a tree_code, specifies the operation
3519    and XARG is the operand.  */
3520
3521 tree
3522 build_x_unary_op (enum tree_code code, tree xarg)
3523 {
3524   tree orig_expr = xarg;
3525   tree exp;
3526   int ptrmem = 0;
3527
3528   if (processing_template_decl)
3529     {
3530       if (type_dependent_expression_p (xarg))
3531         return build_min_nt (code, xarg, NULL_TREE);
3532
3533       xarg = build_non_dependent_expr (xarg);
3534     }
3535
3536   exp = NULL_TREE;
3537
3538   /* [expr.unary.op] says:
3539
3540        The address of an object of incomplete type can be taken.
3541
3542      (And is just the ordinary address operator, not an overloaded
3543      "operator &".)  However, if the type is a template
3544      specialization, we must complete the type at this point so that
3545      an overloaded "operator &" will be available if required.  */
3546   if (code == ADDR_EXPR
3547       && TREE_CODE (xarg) != TEMPLATE_ID_EXPR
3548       && ((CLASS_TYPE_P (TREE_TYPE (xarg))
3549            && !COMPLETE_TYPE_P (complete_type (TREE_TYPE (xarg))))
3550           || (TREE_CODE (xarg) == OFFSET_REF)))
3551     /* Don't look for a function.  */;
3552   else
3553     exp = build_new_op (code, LOOKUP_NORMAL, xarg, NULL_TREE, NULL_TREE,
3554                         /*overloaded_p=*/NULL);
3555   if (!exp && code == ADDR_EXPR)
3556     {
3557       /*  A pointer to member-function can be formed only by saying
3558           &X::mf.  */
3559       if (!flag_ms_extensions && TREE_CODE (TREE_TYPE (xarg)) == METHOD_TYPE
3560           && (TREE_CODE (xarg) != OFFSET_REF || !PTRMEM_OK_P (xarg)))
3561         {
3562           if (TREE_CODE (xarg) != OFFSET_REF)
3563             {
3564               error ("invalid use of %qE to form a pointer-to-member-function."
3565                      "  Use a qualified-id.",
3566                      xarg);
3567               return error_mark_node;
3568             }
3569           else
3570             {
3571               error ("parenthesis around %qE cannot be used to form a"
3572                      " pointer-to-member-function",
3573                      xarg);
3574               PTRMEM_OK_P (xarg) = 1;
3575             }
3576         }
3577
3578       if (TREE_CODE (xarg) == OFFSET_REF)
3579         {
3580           ptrmem = PTRMEM_OK_P (xarg);
3581
3582           if (!ptrmem && !flag_ms_extensions
3583               && TREE_CODE (TREE_TYPE (TREE_OPERAND (xarg, 1))) == METHOD_TYPE)
3584             {
3585               /* A single non-static member, make sure we don't allow a
3586                  pointer-to-member.  */
3587               xarg = build2 (OFFSET_REF, TREE_TYPE (xarg),
3588                              TREE_OPERAND (xarg, 0),
3589                              ovl_cons (TREE_OPERAND (xarg, 1), NULL_TREE));
3590               PTRMEM_OK_P (xarg) = ptrmem;
3591             }
3592         }
3593       else if (TREE_CODE (xarg) == TARGET_EXPR)
3594         warning ("taking address of temporary");
3595       exp = build_unary_op (ADDR_EXPR, xarg, 0);
3596     }
3597
3598   if (processing_template_decl && exp != error_mark_node)
3599     exp = build_min_non_dep (code, exp, orig_expr,
3600                              /*For {PRE,POST}{INC,DEC}REMENT_EXPR*/NULL_TREE);
3601   if (TREE_CODE (exp) == ADDR_EXPR)
3602     PTRMEM_OK_P (exp) = ptrmem;
3603   return exp;
3604 }
3605
3606 /* Like c_common_truthvalue_conversion, but handle pointer-to-member
3607    constants, where a null value is represented by an INTEGER_CST of
3608    -1.  */
3609
3610 tree
3611 cp_truthvalue_conversion (tree expr)
3612 {
3613   tree type = TREE_TYPE (expr);
3614   if (TYPE_PTRMEM_P (type))
3615     return build_binary_op (NE_EXPR, expr, integer_zero_node, 1);
3616   else
3617     return c_common_truthvalue_conversion (expr);
3618 }
3619
3620 /* Just like cp_truthvalue_conversion, but we want a CLEANUP_POINT_EXPR.  */
3621
3622 tree
3623 condition_conversion (tree expr)
3624 {
3625   tree t;
3626   if (processing_template_decl)
3627     return expr;
3628   t = perform_implicit_conversion (boolean_type_node, expr);
3629   t = fold_build_cleanup_point_expr (boolean_type_node, t);
3630   return t;
3631 }
3632
3633 /* Return an ADDR_EXPR giving the address of T.  This function
3634    attempts no optimizations or simplifications; it is a low-level
3635    primitive.  */
3636
3637 tree
3638 build_address (tree t)
3639 {
3640   tree addr;
3641
3642   if (error_operand_p (t) || !cxx_mark_addressable (t))
3643     return error_mark_node;
3644
3645   addr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (t)), t);
3646
3647   return addr;
3648 }
3649
3650 /* Return a NOP_EXPR converting EXPR to TYPE.  */
3651
3652 tree
3653 build_nop (tree type, tree expr)
3654 {
3655   if (type == error_mark_node || error_operand_p (expr))
3656     return expr;
3657   return build1 (NOP_EXPR, type, expr);
3658 }
3659
3660 /* C++: Must handle pointers to members.
3661
3662    Perhaps type instantiation should be extended to handle conversion
3663    from aggregates to types we don't yet know we want?  (Or are those
3664    cases typically errors which should be reported?)
3665
3666    NOCONVERT nonzero suppresses the default promotions
3667    (such as from short to int).  */
3668
3669 tree
3670 build_unary_op (enum tree_code code, tree xarg, int noconvert)
3671 {
3672   /* No default_conversion here.  It causes trouble for ADDR_EXPR.  */
3673   tree arg = xarg;
3674   tree argtype = 0;
3675   const char *errstring = NULL;
3676   tree val;
3677
3678   if (arg == error_mark_node)
3679     return error_mark_node;
3680
3681   switch (code)
3682     {
3683     /* CONVERT_EXPR stands for unary plus in this context.  */
3684     case CONVERT_EXPR:
3685     case NEGATE_EXPR:
3686       {
3687         int flags = WANT_ARITH | WANT_ENUM;
3688         /* Unary plus (but not unary minus) is allowed on pointers.  */
3689         if (code == CONVERT_EXPR)
3690           flags |= WANT_POINTER;
3691         arg = build_expr_type_conversion (flags, arg, true);
3692         if (!arg)
3693           errstring = (code == NEGATE_EXPR
3694                        ? "wrong type argument to unary minus"
3695                        : "wrong type argument to unary plus");
3696         else
3697           {
3698             if (!noconvert && CP_INTEGRAL_TYPE_P (TREE_TYPE (arg)))
3699               arg = perform_integral_promotions (arg);
3700
3701             /* Make sure the result is not a lvalue: a unary plus or minus
3702                expression is always a rvalue.  */
3703             if (real_lvalue_p (arg))
3704               arg = build1 (NON_LVALUE_EXPR, TREE_TYPE (arg), arg);
3705           }
3706       }
3707       break;
3708
3709     case BIT_NOT_EXPR:
3710       if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
3711         {
3712           code = CONJ_EXPR;
3713           if (!noconvert)
3714             arg = default_conversion (arg);
3715         }
3716       else if (!(arg = build_expr_type_conversion (WANT_INT | WANT_ENUM,
3717                                                    arg, true)))
3718         errstring = "wrong type argument to bit-complement";
3719       else if (!noconvert)
3720         arg = perform_integral_promotions (arg);
3721       break;
3722
3723     case ABS_EXPR:
3724       if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_ENUM, arg, true)))
3725         errstring = "wrong type argument to abs";
3726       else if (!noconvert)
3727         arg = default_conversion (arg);
3728       break;
3729
3730     case CONJ_EXPR:
3731       /* Conjugating a real value is a no-op, but allow it anyway.  */
3732       if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_ENUM, arg, true)))
3733         errstring = "wrong type argument to conjugation";
3734       else if (!noconvert)
3735         arg = default_conversion (arg);
3736       break;
3737
3738     case TRUTH_NOT_EXPR:
3739       arg = perform_implicit_conversion (boolean_type_node, arg);
3740       val = invert_truthvalue (arg);
3741       if (arg != error_mark_node)
3742         return val;
3743       errstring = "in argument to unary !";
3744       break;
3745
3746     case NOP_EXPR:
3747       break;
3748
3749     case REALPART_EXPR:
3750       if (TREE_CODE (arg) == COMPLEX_CST)
3751         return TREE_REALPART (arg);
3752       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
3753         {
3754           arg = build1 (REALPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg);
3755           return fold_if_not_in_template (arg);
3756         }
3757       else
3758         return arg;
3759
3760     case IMAGPART_EXPR:
3761       if (TREE_CODE (arg) == COMPLEX_CST)
3762         return TREE_IMAGPART (arg);
3763       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
3764         {
3765           arg = build1 (IMAGPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg);
3766           return fold_if_not_in_template (arg);
3767         }
3768       else
3769         return cp_convert (TREE_TYPE (arg), integer_zero_node);
3770
3771     case PREINCREMENT_EXPR:
3772     case POSTINCREMENT_EXPR:
3773     case PREDECREMENT_EXPR:
3774     case POSTDECREMENT_EXPR:
3775       /* Handle complex lvalues (when permitted)
3776          by reduction to simpler cases.  */
3777
3778       val = unary_complex_lvalue (code, arg);
3779       if (val != 0)
3780         return val;
3781
3782       /* Increment or decrement the real part of the value,
3783          and don't change the imaginary part.  */
3784       if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
3785         {
3786           tree real, imag;
3787
3788           arg = stabilize_reference (arg);
3789           real = build_unary_op (REALPART_EXPR, arg, 1);
3790           imag = build_unary_op (IMAGPART_EXPR, arg, 1);
3791           return build2 (COMPLEX_EXPR, TREE_TYPE (arg),
3792                          build_unary_op (code, real, 1), imag);
3793         }
3794
3795       /* Report invalid types.  */
3796
3797       if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_POINTER,
3798                                               arg, true)))
3799         {
3800           if (code == PREINCREMENT_EXPR)
3801             errstring ="no pre-increment operator for type";
3802           else if (code == POSTINCREMENT_EXPR)
3803             errstring ="no post-increment operator for type";
3804           else if (code == PREDECREMENT_EXPR)
3805             errstring ="no pre-decrement operator for type";
3806           else
3807             errstring ="no post-decrement operator for type";
3808           break;
3809         }
3810
3811       /* Report something read-only.  */
3812
3813       if (CP_TYPE_CONST_P (TREE_TYPE (arg))
3814           || TREE_READONLY (arg))
3815         readonly_error (arg, ((code == PREINCREMENT_EXPR
3816                                || code == POSTINCREMENT_EXPR)
3817                               ? "increment" : "decrement"),
3818                         0);
3819
3820       {
3821         tree inc;
3822         tree result_type = TREE_TYPE (arg);
3823
3824         arg = get_unwidened (arg, 0);
3825         argtype = TREE_TYPE (arg);
3826
3827         /* ARM $5.2.5 last annotation says this should be forbidden.  */
3828         if (TREE_CODE (argtype) == ENUMERAL_TYPE)
3829           pedwarn ("ISO C++ forbids %sing an enum",
3830                    (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
3831                    ? "increment" : "decrement");
3832
3833         /* Compute the increment.  */
3834
3835         if (TREE_CODE (argtype) == POINTER_TYPE)
3836           {
3837             tree type = complete_type (TREE_TYPE (argtype));
3838
3839             if (!COMPLETE_OR_VOID_TYPE_P (type))
3840               error ("cannot %s a pointer to incomplete type %qT",
3841                      ((code == PREINCREMENT_EXPR
3842                        || code == POSTINCREMENT_EXPR)
3843                       ? "increment" : "decrement"), TREE_TYPE (argtype));
3844             else if ((pedantic || warn_pointer_arith)
3845                      && !TYPE_PTROB_P (argtype))
3846               pedwarn ("ISO C++ forbids %sing a pointer of type %qT",
3847                        ((code == PREINCREMENT_EXPR
3848                          || code == POSTINCREMENT_EXPR)
3849                         ? "increment" : "decrement"), argtype);
3850             inc = cxx_sizeof_nowarn (TREE_TYPE (argtype));
3851           }
3852         else
3853           inc = integer_one_node;
3854
3855         inc = cp_convert (argtype, inc);
3856
3857         /* Handle incrementing a cast-expression.  */
3858
3859         switch (TREE_CODE (arg))
3860           {
3861           case NOP_EXPR:
3862           case CONVERT_EXPR:
3863           case FLOAT_EXPR:
3864           case FIX_TRUNC_EXPR:
3865           case FIX_FLOOR_EXPR:
3866           case FIX_ROUND_EXPR:
3867           case FIX_CEIL_EXPR:
3868             {
3869               tree incremented, modify, value, compound;
3870               if (! lvalue_p (arg) && pedantic)
3871                 pedwarn ("cast to non-reference type used as lvalue");
3872               arg = stabilize_reference (arg);
3873               if (code == PREINCREMENT_EXPR || code == PREDECREMENT_EXPR)
3874                 value = arg;
3875               else
3876                 value = save_expr (arg);
3877               incremented = build2 (((code == PREINCREMENT_EXPR
3878                                       || code == POSTINCREMENT_EXPR)
3879                                      ? PLUS_EXPR : MINUS_EXPR),
3880                                     argtype, value, inc);
3881
3882               modify = build_modify_expr (arg, NOP_EXPR, incremented);
3883               compound = build2 (COMPOUND_EXPR, TREE_TYPE (arg),
3884                                  modify, value);
3885
3886               /* Eliminate warning about unused result of + or -.  */
3887               TREE_NO_WARNING (compound) = 1;
3888               return compound;
3889             }
3890
3891           default:
3892             break;
3893           }
3894
3895         /* Complain about anything else that is not a true lvalue.  */
3896         if (!lvalue_or_else (arg, ((code == PREINCREMENT_EXPR
3897                                     || code == POSTINCREMENT_EXPR)
3898                                    ? lv_increment : lv_decrement)))
3899           return error_mark_node;
3900
3901         /* Forbid using -- on `bool'.  */
3902         if (TREE_TYPE (arg) == boolean_type_node)
3903           {
3904             if (code == POSTDECREMENT_EXPR || code == PREDECREMENT_EXPR)
3905               {
3906                 error ("invalid use of %<--%> on bool variable %qD", arg);
3907                 return error_mark_node;
3908               }
3909             val = boolean_increment (code, arg);
3910           }
3911         else
3912           val = build2 (code, TREE_TYPE (arg), arg, inc);
3913
3914         TREE_SIDE_EFFECTS (val) = 1;
3915         return cp_convert (result_type, val);
3916       }
3917
3918     case ADDR_EXPR:
3919       /* Note that this operation never does default_conversion
3920          regardless of NOCONVERT.  */
3921
3922       argtype = lvalue_type (arg);
3923
3924       if (TREE_CODE (arg) == OFFSET_REF)
3925         goto offset_ref;
3926
3927       if (TREE_CODE (argtype) == REFERENCE_TYPE)
3928         {
3929           tree type = build_pointer_type (TREE_TYPE (argtype));
3930           arg = build1 (CONVERT_EXPR, type, arg);
3931           return arg;
3932         }
3933       else if (pedantic && DECL_MAIN_P (arg))
3934         /* ARM $3.4 */
3935         pedwarn ("ISO C++ forbids taking address of function %<::main%>");
3936
3937       /* Let &* cancel out to simplify resulting code.  */
3938       if (TREE_CODE (arg) == INDIRECT_REF)
3939         {
3940           /* We don't need to have `current_class_ptr' wrapped in a
3941              NON_LVALUE_EXPR node.  */
3942           if (arg == current_class_ref)
3943             return current_class_ptr;
3944
3945           arg = TREE_OPERAND (arg, 0);
3946           if (TREE_CODE (TREE_TYPE (arg)) == REFERENCE_TYPE)
3947             {
3948               tree type = build_pointer_type (TREE_TYPE (TREE_TYPE (arg)));
3949               arg = build1 (CONVERT_EXPR, type, arg);
3950             }
3951           else if (lvalue_p (arg))
3952             /* Don't let this be an lvalue.  */
3953             return non_lvalue (arg);
3954           return arg;
3955         }
3956
3957       /* Uninstantiated types are all functions.  Taking the
3958          address of a function is a no-op, so just return the
3959          argument.  */
3960
3961       gcc_assert (TREE_CODE (arg) != IDENTIFIER_NODE
3962                   || !IDENTIFIER_OPNAME_P (arg));
3963
3964       if (TREE_CODE (arg) == COMPONENT_REF && type_unknown_p (arg)
3965           && !really_overloaded_fn (TREE_OPERAND (arg, 1)))
3966         {
3967           /* They're trying to take the address of a unique non-static
3968              member function.  This is ill-formed (except in MS-land),
3969              but let's try to DTRT.
3970              Note: We only handle unique functions here because we don't
3971              want to complain if there's a static overload; non-unique
3972              cases will be handled by instantiate_type.  But we need to
3973              handle this case here to allow casts on the resulting PMF.
3974              We could defer this in non-MS mode, but it's easier to give
3975              a useful error here.  */
3976
3977           /* Inside constant member functions, the `this' pointer
3978              contains an extra const qualifier.  TYPE_MAIN_VARIANT
3979              is used here to remove this const from the diagnostics
3980              and the created OFFSET_REF.  */
3981           tree base = TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg, 0)));
3982           tree name = DECL_NAME (get_first_fn (TREE_OPERAND (arg, 1)));
3983
3984           if (! flag_ms_extensions)
3985             {
3986               if (current_class_type
3987                   && TREE_OPERAND (arg, 0) == current_class_ref)
3988                 /* An expression like &memfn.  */
3989                 pedwarn ("ISO C++ forbids taking the address of an unqualified"
3990                          " or parenthesized non-static member function to form"
3991                          " a pointer to member function.  Say %<&%T::%D%>",
3992                          base, name);
3993               else
3994                 pedwarn ("ISO C++ forbids taking the address of a bound member"
3995                          " function to form a pointer to member function."
3996                          "  Say %<&%T::%D%>",
3997                          base, name);
3998             }
3999           arg = build_offset_ref (base, name, /*address_p=*/true);
4000         }
4001
4002     offset_ref:
4003       if (type_unknown_p (arg))
4004         return build1 (ADDR_EXPR, unknown_type_node, arg);
4005
4006       /* Handle complex lvalues (when permitted)
4007          by reduction to simpler cases.  */
4008       val = unary_complex_lvalue (code, arg);
4009       if (val != 0)
4010         return val;
4011
4012       switch (TREE_CODE (arg))
4013         {
4014         case NOP_EXPR:
4015         case CONVERT_EXPR:
4016         case FLOAT_EXPR:
4017         case FIX_TRUNC_EXPR:
4018         case FIX_FLOOR_EXPR:
4019         case FIX_ROUND_EXPR:
4020         case FIX_CEIL_EXPR:
4021           if (! lvalue_p (arg) && pedantic)
4022             pedwarn ("ISO C++ forbids taking the address of a cast to a non-lvalue expression");
4023           break;
4024
4025         case OVERLOAD:
4026           arg = OVL_CURRENT (arg);
4027           break;
4028
4029         default:
4030           break;
4031         }
4032
4033       /* Allow the address of a constructor if all the elements
4034          are constant.  */
4035       if (TREE_CODE (arg) == CONSTRUCTOR && TREE_HAS_CONSTRUCTOR (arg)
4036           && TREE_CONSTANT (arg))
4037         ;
4038       /* Anything not already handled and not a true memory reference
4039          is an error.  */
4040       else if (TREE_CODE (argtype) != FUNCTION_TYPE
4041                && TREE_CODE (argtype) != METHOD_TYPE
4042                && TREE_CODE (arg) != OFFSET_REF
4043                && !lvalue_or_else (arg, lv_addressof))
4044         return error_mark_node;
4045
4046       if (argtype != error_mark_node)
4047         argtype = build_pointer_type (argtype);
4048
4049       {
4050         tree addr;
4051
4052         if (TREE_CODE (arg) != COMPONENT_REF
4053             /* Inside a template, we are processing a non-dependent
4054                expression so we can just form an ADDR_EXPR with the
4055                correct type.  */
4056             || processing_template_decl)
4057           {
4058             addr = build_address (arg);
4059             if (TREE_CODE (arg) == OFFSET_REF)
4060               PTRMEM_OK_P (addr) = PTRMEM_OK_P (arg);
4061           }
4062         else if (TREE_CODE (TREE_OPERAND (arg, 1)) == BASELINK)
4063           {
4064             tree fn = BASELINK_FUNCTIONS (TREE_OPERAND (arg, 1));
4065
4066             /* We can only get here with a single static member
4067                function.  */
4068             gcc_assert (TREE_CODE (fn) == FUNCTION_DECL
4069                         && DECL_STATIC_FUNCTION_P (fn));
4070             mark_used (fn);
4071             addr = build_address (fn);
4072             if (TREE_SIDE_EFFECTS (TREE_OPERAND (arg, 0)))
4073               /* Do not lose object's side effects.  */
4074               addr = build2 (COMPOUND_EXPR, TREE_TYPE (addr),
4075                              TREE_OPERAND (arg, 0), addr);
4076           }
4077         else if (DECL_C_BIT_FIELD (TREE_OPERAND (arg, 1)))
4078           {
4079             error ("attempt to take address of bit-field structure member %qD",
4080                    TREE_OPERAND (arg, 1));
4081             return error_mark_node;
4082           }
4083         else
4084           {
4085             tree field = TREE_OPERAND (arg, 1);
4086             tree rval = build_unary_op (ADDR_EXPR, TREE_OPERAND (arg, 0), 0);
4087             tree binfo = lookup_base (TREE_TYPE (TREE_TYPE (rval)),
4088                                       decl_type_context (field),
4089                                       ba_check, NULL);
4090
4091             rval = build_base_path (PLUS_EXPR, rval, binfo, 1);
4092
4093             TREE_OPERAND (arg, 0) = build_indirect_ref (rval, NULL);
4094             addr = build_address (arg);
4095           }
4096
4097         if (TREE_CODE (argtype) == POINTER_TYPE
4098             && TREE_CODE (TREE_TYPE (argtype)) == METHOD_TYPE)
4099           {
4100             build_ptrmemfunc_type (argtype);
4101             addr = build_ptrmemfunc (argtype, addr, 0,
4102                                      /*c_cast_p=*/false);
4103           }
4104
4105         return addr;
4106       }
4107
4108     default:
4109       break;
4110     }
4111
4112   if (!errstring)
4113     {
4114       if (argtype == 0)
4115         argtype = TREE_TYPE (arg);
4116       return fold_if_not_in_template (build1 (code, argtype, arg));
4117     }
4118
4119   error ("%s", errstring);
4120   return error_mark_node;
4121 }
4122
4123 /* Apply unary lvalue-demanding operator CODE to the expression ARG
4124    for certain kinds of expressions which are not really lvalues
4125    but which we can accept as lvalues.
4126
4127    If ARG is not a kind of expression we can handle, return
4128    NULL_TREE.  */
4129
4130 tree
4131 unary_complex_lvalue (enum tree_code code, tree arg)
4132 {
4133   /* Inside a template, making these kinds of adjustments is
4134      pointless; we are only concerned with the type of the
4135      expression.  */
4136   if (processing_template_decl)
4137     return NULL_TREE;
4138
4139   /* Handle (a, b) used as an "lvalue".  */
4140   if (TREE_CODE (arg) == COMPOUND_EXPR)
4141     {
4142       tree real_result = build_unary_op (code, TREE_OPERAND (arg, 1), 0);
4143       return build2 (COMPOUND_EXPR, TREE_TYPE (real_result),
4144                      TREE_OPERAND (arg, 0), real_result);
4145     }
4146
4147   /* Handle (a ? b : c) used as an "lvalue".  */
4148   if (TREE_CODE (arg) == COND_EXPR
4149       || TREE_CODE (arg) == MIN_EXPR || TREE_CODE (arg) == MAX_EXPR)
4150     return rationalize_conditional_expr (code, arg);
4151
4152   /* Handle (a = b), (++a), and (--a) used as an "lvalue".  */
4153   if (TREE_CODE (arg) == MODIFY_EXPR
4154       || TREE_CODE (arg) == PREINCREMENT_EXPR
4155       || TREE_CODE (arg) == PREDECREMENT_EXPR)
4156     {
4157       tree lvalue = TREE_OPERAND (arg, 0);
4158       if (TREE_SIDE_EFFECTS (lvalue))
4159         {
4160           lvalue = stabilize_reference (lvalue);
4161           arg = build2 (TREE_CODE (arg), TREE_TYPE (arg),
4162                         lvalue, TREE_OPERAND (arg, 1));
4163         }
4164       return unary_complex_lvalue
4165         (code, build2 (COMPOUND_EXPR, TREE_TYPE (lvalue), arg, lvalue));
4166     }
4167
4168   if (code != ADDR_EXPR)
4169     return 0;
4170
4171   /* Handle (a = b) used as an "lvalue" for `&'.  */
4172   if (TREE_CODE (arg) == MODIFY_EXPR
4173       || TREE_CODE (arg) == INIT_EXPR)
4174     {
4175       tree real_result = build_unary_op (code, TREE_OPERAND (arg, 0), 0);
4176       arg = build2 (COMPOUND_EXPR, TREE_TYPE (real_result),
4177                     arg, real_result);
4178       TREE_NO_WARNING (arg) = 1;
4179       return arg;
4180     }
4181
4182   if (TREE_CODE (TREE_TYPE (arg)) == FUNCTION_TYPE
4183       || TREE_CODE (TREE_TYPE (arg)) == METHOD_TYPE
4184       || TREE_CODE (arg) == OFFSET_REF)
4185     {
4186       tree t;
4187
4188       gcc_assert (TREE_CODE (arg) != SCOPE_REF);
4189
4190       if (TREE_CODE (arg) != OFFSET_REF)
4191         return 0;
4192
4193       t = TREE_OPERAND (arg, 1);
4194
4195       /* Check all this code for right semantics.  */
4196       if (TREE_CODE (t) == FUNCTION_DECL)
4197         {
4198           if (DECL_DESTRUCTOR_P (t))
4199             error ("taking address of destructor");
4200           return build_unary_op (ADDR_EXPR, t, 0);
4201         }
4202       if (TREE_CODE (t) == VAR_DECL)
4203         return build_unary_op (ADDR_EXPR, t, 0);
4204       else
4205         {
4206           tree type;
4207
4208           if (TREE_OPERAND (arg, 0)
4209               && ! is_dummy_object (TREE_OPERAND (arg, 0))
4210               && TREE_CODE (t) != FIELD_DECL)
4211             {
4212               error ("taking address of bound pointer-to-member expression");
4213               return error_mark_node;
4214             }
4215           if (!PTRMEM_OK_P (arg))
4216             return build_unary_op (code, arg, 0);
4217
4218           if (TREE_CODE (TREE_TYPE (t)) == REFERENCE_TYPE)
4219             {
4220               error ("cannot create pointer to reference member %qD", t);
4221               return error_mark_node;
4222             }
4223
4224           type = build_ptrmem_type (context_for_name_lookup (t),
4225                                     TREE_TYPE (t));
4226           t = make_ptrmem_cst (type, TREE_OPERAND (arg, 1));
4227           return t;
4228         }
4229     }
4230
4231
4232   /* We permit compiler to make function calls returning
4233      objects of aggregate type look like lvalues.  */
4234   {
4235     tree targ = arg;
4236
4237     if (TREE_CODE (targ) == SAVE_EXPR)
4238       targ = TREE_OPERAND (targ, 0);
4239
4240     if (TREE_CODE (targ) == CALL_EXPR && IS_AGGR_TYPE (TREE_TYPE (targ)))
4241       {
4242         if (TREE_CODE (arg) == SAVE_EXPR)
4243           targ = arg;
4244         else
4245           targ = build_cplus_new (TREE_TYPE (arg), arg);
4246         return build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (arg)), targ);
4247       }
4248
4249     if (TREE_CODE (arg) == SAVE_EXPR && TREE_CODE (targ) == INDIRECT_REF)
4250       return build3 (SAVE_EXPR, build_pointer_type (TREE_TYPE (arg)),
4251                      TREE_OPERAND (targ, 0), current_function_decl, NULL);
4252   }
4253
4254   /* Don't let anything else be handled specially.  */
4255   return 0;
4256 }
4257 \f
4258 /* Mark EXP saying that we need to be able to take the
4259    address of it; it should not be allocated in a register.
4260    Value is true if successful.
4261
4262    C++: we do not allow `current_class_ptr' to be addressable.  */
4263
4264 bool
4265 cxx_mark_addressable (tree exp)
4266 {
4267   tree x = exp;
4268
4269   while (1)
4270     switch (TREE_CODE (x))
4271       {
4272       case ADDR_EXPR:
4273       case COMPONENT_REF:
4274       case ARRAY_REF:
4275       case REALPART_EXPR:
4276       case IMAGPART_EXPR:
4277         x = TREE_OPERAND (x, 0);
4278         break;
4279
4280       case PARM_DECL:
4281         if (x == current_class_ptr)
4282           {
4283             error ("cannot take the address of %<this%>, which is an rvalue expression");
4284             TREE_ADDRESSABLE (x) = 1; /* so compiler doesn't die later.  */
4285             return true;
4286           }
4287         /* Fall through.  */
4288
4289       case VAR_DECL:
4290         /* Caller should not be trying to mark initialized
4291            constant fields addressable.  */
4292         gcc_assert (DECL_LANG_SPECIFIC (x) == 0
4293                     || DECL_IN_AGGR_P (x) == 0
4294                     || TREE_STATIC (x)
4295                     || DECL_EXTERNAL (x));
4296         /* Fall through.  */
4297
4298       case CONST_DECL:
4299       case RESULT_DECL:
4300         if (DECL_REGISTER (x) && !TREE_ADDRESSABLE (x)
4301             && !DECL_ARTIFICIAL (x))
4302           {
4303             if (DECL_HARD_REGISTER (x) != 0)
4304               {
4305                 error
4306                   ("address of explicit register variable %qD requested", x);
4307                 return false;
4308               }
4309             else if (extra_warnings)
4310               warning
4311                 ("address requested for %qD, which is declared %<register%>", x);
4312           }
4313         TREE_ADDRESSABLE (x) = 1;
4314         return true;
4315
4316       case FUNCTION_DECL:
4317         TREE_ADDRESSABLE (x) = 1;
4318         return true;
4319
4320       case CONSTRUCTOR:
4321         TREE_ADDRESSABLE (x) = 1;
4322         return true;
4323
4324       case TARGET_EXPR:
4325         TREE_ADDRESSABLE (x) = 1;
4326         cxx_mark_addressable (TREE_OPERAND (x, 0));
4327         return true;
4328
4329       default:
4330         return true;
4331     }
4332 }
4333 \f
4334 /* Build and return a conditional expression IFEXP ? OP1 : OP2.  */
4335
4336 tree
4337 build_x_conditional_expr (tree ifexp, tree op1, tree op2)
4338 {
4339   tree orig_ifexp = ifexp;
4340   tree orig_op1 = op1;
4341   tree orig_op2 = op2;
4342   tree expr;
4343
4344   if (processing_template_decl)
4345     {
4346       /* The standard says that the expression is type-dependent if
4347          IFEXP is type-dependent, even though the eventual type of the
4348          expression doesn't dependent on IFEXP.  */
4349       if (type_dependent_expression_p (ifexp)
4350           /* As a GNU extension, the middle operand may be omitted.  */
4351           || (op1 && type_dependent_expression_p (op1))
4352           || type_dependent_expression_p (op2))
4353         return build_min_nt (COND_EXPR, ifexp, op1, op2);
4354       ifexp = build_non_dependent_expr (ifexp);
4355       if (op1)
4356         op1 = build_non_dependent_expr (op1);
4357       op2 = build_non_dependent_expr (op2);
4358     }
4359
4360   expr = build_conditional_expr (ifexp, op1, op2);
4361   if (processing_template_decl && expr != error_mark_node)
4362     return build_min_non_dep (COND_EXPR, expr,
4363                               orig_ifexp, orig_op1, orig_op2);
4364   return expr;
4365 }
4366 \f
4367 /* Given a list of expressions, return a compound expression
4368    that performs them all and returns the value of the last of them.  */
4369
4370 tree build_x_compound_expr_from_list (tree list, const char *msg)
4371 {
4372   tree expr = TREE_VALUE (list);
4373
4374   if (TREE_CHAIN (list))
4375     {
4376       if (msg)
4377         pedwarn ("%s expression list treated as compound expression", msg);
4378
4379       for (list = TREE_CHAIN (list); list; list = TREE_CHAIN (list))
4380         expr = build_x_compound_expr (expr, TREE_VALUE (list));
4381     }
4382
4383   return expr;
4384 }
4385
4386 /* Handle overloading of the ',' operator when needed.  */
4387
4388 tree
4389 build_x_compound_expr (tree op1, tree op2)
4390 {
4391   tree result;
4392   tree orig_op1 = op1;
4393   tree orig_op2 = op2;
4394
4395   if (processing_template_decl)
4396     {
4397       if (type_dependent_expression_p (op1)
4398           || type_dependent_expression_p (op2))
4399         return build_min_nt (COMPOUND_EXPR, op1, op2);
4400       op1 = build_non_dependent_expr (op1);
4401       op2 = build_non_dependent_expr (op2);
4402     }
4403
4404   result = build_new_op (COMPOUND_EXPR, LOOKUP_NORMAL, op1, op2, NULL_TREE,
4405                          /*overloaded_p=*/NULL);
4406   if (!result)
4407     result = build_compound_expr (op1, op2);
4408
4409   if (processing_template_decl && result != error_mark_node)
4410     return build_min_non_dep (COMPOUND_EXPR, result, orig_op1, orig_op2);
4411
4412   return result;
4413 }
4414
4415 /* Build a compound expression.  */
4416
4417 tree
4418 build_compound_expr (tree lhs, tree rhs)
4419 {
4420   lhs = convert_to_void (lhs, "left-hand operand of comma");
4421
4422   if (lhs == error_mark_node || rhs == error_mark_node)
4423     return error_mark_node;
4424
4425   if (TREE_CODE (rhs) == TARGET_EXPR)
4426     {
4427       /* If the rhs is a TARGET_EXPR, then build the compound
4428          expression inside the target_expr's initializer. This
4429          helps the compiler to eliminate unnecessary temporaries.  */
4430       tree init = TREE_OPERAND (rhs, 1);
4431
4432       init = build2 (COMPOUND_EXPR, TREE_TYPE (init), lhs, init);
4433       TREE_OPERAND (rhs, 1) = init;
4434
4435       return rhs;
4436     }
4437
4438   return build2 (COMPOUND_EXPR, TREE_TYPE (rhs), lhs, rhs);
4439 }
4440
4441 /* Issue a diagnostic message if casting from SRC_TYPE to DEST_TYPE
4442    casts away constness.  DIAG_FN gives the function to call if we
4443    need to issue a diagnostic; if it is NULL, no diagnostic will be
4444    issued.  DESCRIPTION explains what operation is taking place.  */
4445
4446 static void
4447 check_for_casting_away_constness (tree src_type, tree dest_type,
4448                                   void (*diag_fn)(const char *, ...),
4449                                   const char *description)
4450 {
4451   if (diag_fn && casts_away_constness (src_type, dest_type))
4452     error ("%s from type %qT to type %qT casts away constness",
4453            description, src_type, dest_type);
4454 }
4455
4456 /* Convert EXPR (an expression with pointer-to-member type) to TYPE
4457    (another pointer-to-member type in the same hierarchy) and return
4458    the converted expression.  If ALLOW_INVERSE_P is permitted, a
4459    pointer-to-derived may be converted to pointer-to-base; otherwise,
4460    only the other direction is permitted.  If C_CAST_P is true, this
4461    conversion is taking place as part of a C-style cast.  */
4462
4463 tree
4464 convert_ptrmem (tree type, tree expr, bool allow_inverse_p,
4465                 bool c_cast_p)
4466 {
4467   if (TYPE_PTRMEM_P (type))
4468     {
4469       tree delta;
4470
4471       if (TREE_CODE (expr) == PTRMEM_CST)
4472         expr = cplus_expand_constant (expr);
4473       delta = get_delta_difference (TYPE_PTRMEM_CLASS_TYPE (TREE_TYPE (expr)),
4474                                     TYPE_PTRMEM_CLASS_TYPE (type),
4475                                     allow_inverse_p,
4476                                     c_cast_p);
4477       if (!integer_zerop (delta))
4478         expr = cp_build_binary_op (PLUS_EXPR,
4479                                    build_nop (ptrdiff_type_node, expr),
4480                                    delta);
4481       return build_nop (type, expr);
4482     }
4483   else
4484     return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr,
4485                              allow_inverse_p, c_cast_p);
4486 }
4487
4488 /* Perform a static_cast from EXPR to TYPE.  When C_CAST_P is true,
4489    this static_cast is being attempted as one of the possible casts
4490    allowed by a C-style cast.  (In that case, accessibility of base
4491    classes is not considered, and it is OK to cast away
4492    constness.)  Return the result of the cast.  *VALID_P is set to
4493    indicate whether or not the cast was valid.  */
4494
4495 static tree
4496 build_static_cast_1 (tree type, tree expr, bool c_cast_p,
4497                      bool *valid_p)
4498 {
4499   tree intype;
4500   tree result;
4501   tree orig;
4502   void (*diag_fn)(const char*, ...);
4503   const char *desc;
4504
4505   /* Assume the cast is valid.  */
4506   *valid_p = true;
4507
4508   intype = TREE_TYPE (expr);
4509
4510   /* Determine what to do when casting away constness.  */
4511   if (c_cast_p)
4512     {
4513       /* C-style casts are allowed to cast away constness.  With
4514          WARN_CAST_QUAL, we still want to issue a warning.  */
4515       diag_fn = warn_cast_qual ? warning : NULL;
4516       desc = "cast";
4517     }
4518   else
4519     {
4520       /* A static_cast may not cast away constness.  */
4521       diag_fn = error;
4522       desc = "static_cast";
4523     }
4524
4525   /* [expr.static.cast]
4526
4527      An lvalue of type "cv1 B", where B is a class type, can be cast
4528      to type "reference to cv2 D", where D is a class derived (clause
4529      _class.derived_) from B, if a valid standard conversion from
4530      "pointer to D" to "pointer to B" exists (_conv.ptr_), cv2 is the
4531      same cv-qualification as, or greater cv-qualification than, cv1,
4532      and B is not a virtual base class of D.  */
4533   /* We check this case before checking the validity of "TYPE t =
4534      EXPR;" below because for this case:
4535
4536        struct B {};
4537        struct D : public B { D(const B&); };
4538        extern B& b;
4539        void f() { static_cast<const D&>(b); }
4540
4541      we want to avoid constructing a new D.  The standard is not
4542      completely clear about this issue, but our interpretation is
4543      consistent with other compilers.  */
4544   if (TREE_CODE (type) == REFERENCE_TYPE
4545       && CLASS_TYPE_P (TREE_TYPE (type))
4546       && CLASS_TYPE_P (intype)
4547       && real_lvalue_p (expr)
4548       && DERIVED_FROM_P (intype, TREE_TYPE (type))
4549       && can_convert (build_pointer_type (TYPE_MAIN_VARIANT (intype)),
4550                       build_pointer_type (TYPE_MAIN_VARIANT
4551                                           (TREE_TYPE (type))))
4552       && (c_cast_p
4553           || at_least_as_qualified_p (TREE_TYPE (type), intype)))
4554     {
4555       tree base;
4556
4557       /* There is a standard conversion from "D*" to "B*" even if "B"
4558          is ambiguous or inaccessible.  If this is really a
4559          static_cast, then we check both for inaccessibility and
4560          ambiguity.  However, if this is a static_cast being performed
4561          because the user wrote a C-style cast, then accessibility is
4562          not considered.  */
4563       base = lookup_base (TREE_TYPE (type), intype,
4564                           c_cast_p ? ba_unique : ba_check,
4565                           NULL);
4566
4567       /* Convert from "B*" to "D*".  This function will check that "B"
4568          is not a virtual base of "D".  */
4569       expr = build_base_path (MINUS_EXPR, build_address (expr),
4570                               base, /*nonnull=*/false);
4571       /* Convert the pointer to a reference -- but then remember that
4572          there are no expressions with reference type in C++.  */
4573       return convert_from_reference (build_nop (type, expr));
4574     }
4575
4576   orig = expr;
4577
4578   /* [expr.static.cast]
4579
4580      An expression e can be explicitly converted to a type T using a
4581      static_cast of the form static_cast<T>(e) if the declaration T
4582      t(e);" is well-formed, for some invented temporary variable
4583      t.  */
4584   result = perform_direct_initialization_if_possible (type, expr,
4585                                                       c_cast_p);
4586   if (result)
4587     {
4588       result = convert_from_reference (result);
4589
4590       /* Ignore any integer overflow caused by the cast.  */
4591       if (TREE_CODE (result) == INTEGER_CST
4592           && CONSTANT_CLASS_P (orig))
4593         {
4594           TREE_OVERFLOW (result) = TREE_OVERFLOW (orig);
4595           TREE_CONSTANT_OVERFLOW (result)
4596             = TREE_CONSTANT_OVERFLOW (orig);
4597         }
4598       /* [expr.static.cast]
4599
4600          If T is a reference type, the result is an lvalue; otherwise,
4601          the result is an rvalue.  */
4602       if (TREE_CODE (type) != REFERENCE_TYPE
4603           && real_lvalue_p (result))
4604         result = build1 (NON_LVALUE_EXPR, TREE_TYPE (result), result);
4605       return result;
4606     }
4607
4608   /* [expr.static.cast]
4609
4610      Any expression can be explicitly converted to type cv void.  */
4611   if (TREE_CODE (type) == VOID_TYPE)
4612     return convert_to_void (expr, /*implicit=*/NULL);
4613
4614   /* [expr.static.cast]
4615
4616      The inverse of any standard conversion sequence (clause _conv_),
4617      other than the lvalue-to-rvalue (_conv.lval_), array-to-pointer
4618      (_conv.array_), function-to-pointer (_conv.func_), and boolean
4619      (_conv.bool_) conversions, can be performed explicitly using
4620      static_cast subject to the restriction that the explicit
4621      conversion does not cast away constness (_expr.const.cast_), and
4622      the following additional rules for specific cases:  */
4623   /* For reference, the conversions not excluded are: integral
4624      promotions, floating point promotion, integral conversions,
4625      floating point conversions, floating-integral conversions,
4626      pointer conversions, and pointer to member conversions.  */
4627   if ((ARITHMETIC_TYPE_P (type) && ARITHMETIC_TYPE_P (intype))
4628       /* DR 128
4629
4630          A value of integral _or enumeration_ type can be explicitly
4631          converted to an enumeration type.  */
4632       || (INTEGRAL_OR_ENUMERATION_TYPE_P (type)
4633           && INTEGRAL_OR_ENUMERATION_TYPE_P (intype)))
4634     {
4635       expr = ocp_convert (type, expr, CONV_C_CAST, LOOKUP_NORMAL);
4636
4637       /* Ignore any integer overflow caused by the cast.  */
4638       if (TREE_CODE (expr) == INTEGER_CST
4639           && CONSTANT_CLASS_P (orig))
4640         {
4641           TREE_OVERFLOW (expr) = TREE_OVERFLOW (orig);
4642           TREE_CONSTANT_OVERFLOW (expr) = TREE_CONSTANT_OVERFLOW (orig);
4643         }
4644       return expr;
4645     }
4646
4647   if (TYPE_PTR_P (type) && TYPE_PTR_P (intype)
4648       && CLASS_TYPE_P (TREE_TYPE (type))
4649       && CLASS_TYPE_P (TREE_TYPE (intype))
4650       && can_convert (build_pointer_type (TYPE_MAIN_VARIANT
4651                                           (TREE_TYPE (intype))),
4652                       build_pointer_type (TYPE_MAIN_VARIANT
4653                                           (TREE_TYPE (type)))))
4654     {
4655       tree base;
4656
4657       if (!c_cast_p)
4658         check_for_casting_away_constness (intype, type, diag_fn, desc);
4659       base = lookup_base (TREE_TYPE (type), TREE_TYPE (intype),
4660                           c_cast_p ? ba_unique : ba_check,
4661                           NULL);
4662       return build_base_path (MINUS_EXPR, expr, base, /*nonnull=*/false);
4663     }
4664
4665   if ((TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
4666       || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
4667     {
4668       tree c1;
4669       tree c2;
4670       tree t1;
4671       tree t2;
4672
4673       c1 = TYPE_PTRMEM_CLASS_TYPE (intype);
4674       c2 = TYPE_PTRMEM_CLASS_TYPE (type);
4675
4676       if (TYPE_PTRMEM_P (type))
4677         {
4678           t1 = (build_ptrmem_type
4679                 (c1,
4680                  TYPE_MAIN_VARIANT (TYPE_PTRMEM_POINTED_TO_TYPE (intype))));
4681           t2 = (build_ptrmem_type
4682                 (c2,
4683                  TYPE_MAIN_VARIANT (TYPE_PTRMEM_POINTED_TO_TYPE (type))));
4684         }
4685       else
4686         {
4687           t1 = intype;
4688           t2 = type;
4689         }
4690       if (can_convert (t1, t2))
4691         {
4692           if (!c_cast_p)
4693             check_for_casting_away_constness (intype, type, diag_fn,
4694                                               desc);
4695           return convert_ptrmem (type, expr, /*allow_inverse_p=*/1,
4696                                  c_cast_p);
4697         }
4698     }
4699
4700   /* [expr.static.cast]
4701
4702      An rvalue of type "pointer to cv void" can be explicitly
4703      converted to a pointer to object type.  A value of type pointer
4704      to object converted to "pointer to cv void" and back to the
4705      original pointer type will have its original value.  */
4706   if (TREE_CODE (intype) == POINTER_TYPE
4707       && VOID_TYPE_P (TREE_TYPE (intype))
4708       && TYPE_PTROB_P (type))
4709     {
4710       if (!c_cast_p)
4711         check_for_casting_away_constness (intype, type, diag_fn, desc);
4712       return build_nop (type, expr);
4713     }
4714
4715   *valid_p = false;
4716   return error_mark_node;
4717 }
4718
4719 /* Return an expression representing static_cast<TYPE>(EXPR).  */
4720
4721 tree
4722 build_static_cast (tree type, tree expr)
4723 {
4724   tree result;
4725   bool valid_p;
4726
4727   if (type == error_mark_node || expr == error_mark_node)
4728     return error_mark_node;
4729
4730   if (processing_template_decl)
4731     {
4732       expr = build_min (STATIC_CAST_EXPR, type, expr);
4733       /* We don't know if it will or will not have side effects.  */
4734       TREE_SIDE_EFFECTS (expr) = 1;
4735       return convert_from_reference (expr);
4736     }
4737
4738   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
4739      Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
4740   if (TREE_CODE (type) != REFERENCE_TYPE
4741       && TREE_CODE (expr) == NOP_EXPR
4742       && TREE_TYPE (expr) == TREE_TYPE (TREE_OPERAND (expr, 0)))
4743     expr = TREE_OPERAND (expr, 0);
4744
4745   result = build_static_cast_1 (type, expr, /*c_cast_p=*/false, &valid_p);
4746   if (valid_p)
4747     return result;
4748
4749   error ("invalid static_cast from type %qT to type %qT",
4750          TREE_TYPE (expr), type);
4751   return error_mark_node;
4752 }
4753
4754 /* EXPR is an expression with member function or pointer-to-member
4755    function type.  TYPE is a pointer type.  Converting EXPR to TYPE is
4756    not permitted by ISO C++, but we accept it in some modes.  If we
4757    are not in one of those modes, issue a diagnostic.  Return the
4758    converted expression.  */
4759
4760 tree
4761 convert_member_func_to_ptr (tree type, tree expr)
4762 {
4763   tree intype;
4764   tree decl;
4765
4766   intype = TREE_TYPE (expr);
4767   gcc_assert (TYPE_PTRMEMFUNC_P (intype)
4768               || TREE_CODE (intype) == METHOD_TYPE);
4769
4770   if (pedantic || warn_pmf2ptr)
4771     pedwarn ("converting from %qT to %qT", intype, type);
4772
4773   if (TREE_CODE (intype) == METHOD_TYPE)
4774     expr = build_addr_func (expr);
4775   else if (TREE_CODE (expr) == PTRMEM_CST)
4776     expr = build_address (PTRMEM_CST_MEMBER (expr));
4777   else
4778     {
4779       decl = maybe_dummy_object (TYPE_PTRMEM_CLASS_TYPE (intype), 0);
4780       decl = build_address (decl);
4781       expr = get_member_function_from_ptrfunc (&decl, expr);
4782     }
4783
4784   return build_nop (type, expr);
4785 }
4786
4787 /* Return a representation for a reinterpret_cast from EXPR to TYPE.
4788    If C_CAST_P is true, this reinterpret cast is being done as part of
4789    a C-style cast.  If VALID_P is non-NULL, *VALID_P is set to
4790    indicate whether or not reinterpret_cast was valid.  */
4791
4792 static tree
4793 build_reinterpret_cast_1 (tree type, tree expr, bool c_cast_p,
4794                           bool *valid_p)
4795 {
4796   tree intype;
4797
4798   /* Assume the cast is invalid.  */
4799   if (valid_p)
4800     *valid_p = true;
4801
4802   if (type == error_mark_node || error_operand_p (expr))
4803     return error_mark_node;
4804
4805   intype = TREE_TYPE (expr);
4806
4807   /* [expr.reinterpret.cast]
4808      An lvalue expression of type T1 can be cast to the type
4809      "reference to T2" if an expression of type "pointer to T1" can be
4810      explicitly converted to the type "pointer to T2" using a
4811      reinterpret_cast.  */
4812   if (TREE_CODE (type) == REFERENCE_TYPE)
4813     {
4814       if (! real_lvalue_p (expr))
4815         {
4816           error ("invalid cast of an rvalue expression of type "
4817                  "%qT to type %qT",
4818                  intype, type);
4819           return error_mark_node;
4820         }
4821
4822       /* Warn about a reinterpret_cast from "A*" to "B&" if "A" and
4823          "B" are related class types; the reinterpret_cast does not
4824          adjust the pointer.  */
4825       if (TYPE_PTR_P (intype)
4826           && (comptypes (TREE_TYPE (intype), TREE_TYPE (type),
4827                          COMPARE_BASE | COMPARE_DERIVED)))
4828         warning ("casting %qT to %qT does not dereference pointer",
4829                  intype, type);
4830
4831       expr = build_unary_op (ADDR_EXPR, expr, 0);
4832       if (expr != error_mark_node)
4833         expr = build_reinterpret_cast_1
4834           (build_pointer_type (TREE_TYPE (type)), expr, c_cast_p,
4835            valid_p);
4836       if (expr != error_mark_node)
4837         expr = build_indirect_ref (expr, 0);
4838       return expr;
4839     }
4840
4841   /* As a G++ extension, we consider conversions from member
4842      functions, and pointers to member functions to
4843      pointer-to-function and pointer-to-void types.  If
4844      -Wno-pmf-conversions has not been specified,
4845      convert_member_func_to_ptr will issue an error message.  */
4846   if ((TYPE_PTRMEMFUNC_P (intype)
4847        || TREE_CODE (intype) == METHOD_TYPE)
4848       && TYPE_PTR_P (type)
4849       && (TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE
4850           || VOID_TYPE_P (TREE_TYPE (type))))
4851     return convert_member_func_to_ptr (type, expr);
4852
4853   /* If the cast is not to a reference type, the lvalue-to-rvalue,
4854      array-to-pointer, and function-to-pointer conversions are
4855      performed.  */
4856   expr = decay_conversion (expr);
4857
4858   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
4859      Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
4860   if (TREE_CODE (expr) == NOP_EXPR
4861       && TREE_TYPE (expr) == TREE_TYPE (TREE_OPERAND (expr, 0)))
4862     expr = TREE_OPERAND (expr, 0);
4863
4864   if (error_operand_p (expr))
4865     return error_mark_node;
4866
4867   intype = TREE_TYPE (expr);
4868
4869   /* [expr.reinterpret.cast]
4870      A pointer can be converted to any integral type large enough to
4871      hold it.  */
4872   if (CP_INTEGRAL_TYPE_P (type) && TYPE_PTR_P (intype))
4873     {
4874       if (TYPE_PRECISION (type) < TYPE_PRECISION (intype))
4875         pedwarn ("cast from %qT to %qT loses precision",
4876                  intype, type);
4877     }
4878   /* [expr.reinterpret.cast]
4879      A value of integral or enumeration type can be explicitly
4880      converted to a pointer.  */
4881   else if (TYPE_PTR_P (type) && INTEGRAL_OR_ENUMERATION_TYPE_P (intype))
4882     /* OK */
4883     ;
4884   else if ((TYPE_PTRFN_P (type) && TYPE_PTRFN_P (intype))
4885            || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
4886     return fold_if_not_in_template (build_nop (type, expr));
4887   else if ((TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
4888            || (TYPE_PTROBV_P (type) && TYPE_PTROBV_P (intype)))
4889     {
4890       if (!c_cast_p)
4891         check_for_casting_away_constness (intype, type, error,
4892                                           "reinterpret_cast");
4893       /* Warn about possible alignment problems.  */
4894       if (STRICT_ALIGNMENT && warn_cast_align
4895           && !VOID_TYPE_P (type)
4896           && TREE_CODE (TREE_TYPE (intype)) != FUNCTION_TYPE
4897           && COMPLETE_TYPE_P (TREE_TYPE (type))
4898           && COMPLETE_TYPE_P (TREE_TYPE (intype))
4899           && TYPE_ALIGN (TREE_TYPE (type)) > TYPE_ALIGN (TREE_TYPE (intype)))
4900         warning ("cast from %qT to %qT increases required alignment of "
4901                  "target type",
4902                  intype, type);
4903
4904       return fold_if_not_in_template (build_nop (type, expr));
4905     }
4906   else if ((TYPE_PTRFN_P (type) && TYPE_PTROBV_P (intype))
4907            || (TYPE_PTRFN_P (intype) && TYPE_PTROBV_P (type)))
4908     {
4909       if (pedantic)
4910         /* Only issue a warning, as we have always supported this
4911            where possible, and it is necessary in some cases.  DR 195
4912            addresses this issue, but as of 2004/10/26 is still in
4913            drafting.  */
4914         warning ("ISO C++ forbids casting between pointer-to-function and pointer-to-object");
4915       return fold_if_not_in_template (build_nop (type, expr));
4916     }
4917   else if (TREE_CODE (type) == VECTOR_TYPE)
4918     return fold_if_not_in_template (convert_to_vector (type, expr));
4919   else if (TREE_CODE (intype) == VECTOR_TYPE)
4920     return fold_if_not_in_template (convert_to_integer (type, expr));
4921   else
4922     {
4923       if (valid_p)
4924         *valid_p = false;
4925       error ("invalid cast from type %qT to type %qT", intype, type);
4926       return error_mark_node;
4927     }
4928
4929   return cp_convert (type, expr);
4930 }
4931
4932 tree
4933 build_reinterpret_cast (tree type, tree expr)
4934 {
4935   if (type == error_mark_node || expr == error_mark_node)
4936     return error_mark_node;
4937
4938   if (processing_template_decl)
4939     {
4940       tree t = build_min (REINTERPRET_CAST_EXPR, type, expr);
4941
4942       if (!TREE_SIDE_EFFECTS (t)
4943           && type_dependent_expression_p (expr))
4944         /* There might turn out to be side effects inside expr.  */
4945         TREE_SIDE_EFFECTS (t) = 1;
4946       return convert_from_reference (t);
4947     }
4948
4949   return build_reinterpret_cast_1 (type, expr, /*c_cast_p=*/false,
4950                                    /*valid_p=*/NULL);
4951 }
4952
4953 /* Perform a const_cast from EXPR to TYPE.  If the cast is valid,
4954    return an appropriate expression.  Otherwise, return
4955    error_mark_node.  If the cast is not valid, and COMPLAIN is true,
4956    then a diagnostic will be issued.  If VALID_P is non-NULL, its
4957    value upon return will indicate whether or not the conversion
4958    succeeded.  */
4959
4960 static tree
4961 build_const_cast_1 (tree dst_type, tree expr, bool complain,
4962                     bool *valid_p)
4963 {
4964   tree src_type;
4965   tree reference_type;
4966
4967   /* Callers are responsible for handling error_mark_node as a
4968      destination type.  */
4969   gcc_assert (dst_type != error_mark_node);
4970   /* In a template, callers should be building syntactic
4971      representations of casts, not using this machinery.  */
4972   gcc_assert (!processing_template_decl);
4973
4974   /* Assume the conversion is invalid.  */
4975   if (valid_p)
4976     *valid_p = false;
4977
4978   if (!POINTER_TYPE_P (dst_type) && !TYPE_PTRMEM_P (dst_type))
4979     {
4980       if (complain)
4981         error ("invalid use of const_cast with type %qT, "
4982                "which is not a pointer, "
4983                "reference, nor a pointer-to-data-member type", dst_type);
4984       return error_mark_node;
4985     }
4986
4987   if (TREE_CODE (TREE_TYPE (dst_type)) == FUNCTION_TYPE)
4988     {
4989       if (complain)
4990         error ("invalid use of const_cast with type %qT, which is a pointer "
4991                "or reference to a function type", dst_type);
4992       return error_mark_node;
4993     }
4994
4995   src_type = TREE_TYPE (expr);
4996   /* Expressions do not really have reference types.  */
4997   if (TREE_CODE (src_type) == REFERENCE_TYPE)
4998     src_type = TREE_TYPE (src_type);
4999
5000   /* [expr.const.cast]
5001
5002      An lvalue of type T1 can be explicitly converted to an lvalue of
5003      type T2 using the cast const_cast<T2&> (where T1 and T2 are object
5004      types) if a pointer to T1 can be explicitly converted to the type
5005      pointer to T2 using a const_cast.  */
5006   if (TREE_CODE (dst_type) == REFERENCE_TYPE)
5007     {
5008       reference_type = dst_type;
5009       if (! real_lvalue_p (expr))
5010         {
5011           if (complain)
5012             error ("invalid const_cast of an rvalue of type %qT to type %qT",
5013                    src_type, dst_type);
5014           return error_mark_node;
5015         }
5016       dst_type = build_pointer_type (TREE_TYPE (dst_type));
5017       src_type = build_pointer_type (src_type);
5018     }
5019   else
5020     {
5021       reference_type = NULL_TREE;
5022       /* If the destination type is not a reference type, the
5023          lvalue-to-rvalue, array-to-pointer, and function-to-pointer
5024          conversions are performed.  */
5025       src_type = type_decays_to (src_type);
5026       if (src_type == error_mark_node)
5027         return error_mark_node;
5028     }
5029
5030   if ((TYPE_PTR_P (src_type) || TYPE_PTRMEM_P (src_type))
5031       && comp_ptr_ttypes_const (dst_type, src_type))
5032     {
5033       if (valid_p)
5034         *valid_p = true;
5035       if (reference_type)
5036         {
5037           expr = build_unary_op (ADDR_EXPR, expr, 0);
5038           expr = build_nop (reference_type, expr);
5039           return convert_from_reference (expr);
5040         }
5041       else
5042         {
5043           expr = decay_conversion (expr);
5044           /* build_c_cast puts on a NOP_EXPR to make the result not an
5045              lvalue.  Strip such NOP_EXPRs if VALUE is being used in
5046              non-lvalue context.  */
5047           if (TREE_CODE (expr) == NOP_EXPR
5048               && TREE_TYPE (expr) == TREE_TYPE (TREE_OPERAND (expr, 0)))
5049             expr = TREE_OPERAND (expr, 0);
5050           return build_nop (dst_type, expr);
5051         }
5052     }
5053
5054   if (complain)
5055     error ("invalid const_cast from type %qT to type %qT",
5056            src_type, dst_type);
5057   return error_mark_node;
5058 }
5059
5060 tree
5061 build_const_cast (tree type, tree expr)
5062 {
5063   if (type == error_mark_node || error_operand_p (expr))
5064     return error_mark_node;
5065
5066   if (processing_template_decl)
5067     {
5068       tree t = build_min (CONST_CAST_EXPR, type, expr);
5069
5070       if (!TREE_SIDE_EFFECTS (t)
5071           && type_dependent_expression_p (expr))
5072         /* There might turn out to be side effects inside expr.  */
5073         TREE_SIDE_EFFECTS (t) = 1;
5074       return convert_from_reference (t);
5075     }
5076
5077   return build_const_cast_1 (type, expr, /*complain=*/true,
5078                              /*valid_p=*/NULL);
5079 }
5080
5081 /* Build an expression representing an explicit C-style cast to type
5082    TYPE of expression EXPR.  */
5083
5084 tree
5085 build_c_cast (tree type, tree expr)
5086 {
5087   tree value = expr;
5088   tree result;
5089   bool valid_p;
5090
5091   if (type == error_mark_node || error_operand_p (expr))
5092     return error_mark_node;
5093
5094   if (processing_template_decl)
5095     {
5096       tree t = build_min (CAST_EXPR, type,
5097                           tree_cons (NULL_TREE, value, NULL_TREE));
5098       /* We don't know if it will or will not have side effects.  */
5099       TREE_SIDE_EFFECTS (t) = 1;
5100       return convert_from_reference (t);
5101     }
5102
5103   /* Casts to a (pointer to a) specific ObjC class (or 'id' or
5104      'Class') should always be retained, because this information aids
5105      in method lookup.  */
5106   if (objc_is_object_ptr (type)
5107       && objc_is_object_ptr (TREE_TYPE (expr)))
5108     return build_nop (type, expr);
5109
5110   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
5111      Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
5112   if (TREE_CODE (type) != REFERENCE_TYPE
5113       && TREE_CODE (value) == NOP_EXPR
5114       && TREE_TYPE (value) == TREE_TYPE (TREE_OPERAND (value, 0)))
5115     value = TREE_OPERAND (value, 0);
5116
5117   if (TREE_CODE (type) == ARRAY_TYPE)
5118     {
5119       /* Allow casting from T1* to T2[] because Cfront allows it.
5120          NIHCL uses it. It is not valid ISO C++ however.  */
5121       if (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE)
5122         {
5123           pedwarn ("ISO C++ forbids casting to an array type %qT", type);
5124           type = build_pointer_type (TREE_TYPE (type));
5125         }
5126       else
5127         {
5128           error ("ISO C++ forbids casting to an array type %qT", type);
5129           return error_mark_node;
5130         }
5131     }
5132
5133   if (TREE_CODE (type) == FUNCTION_TYPE
5134       || TREE_CODE (type) == METHOD_TYPE)
5135     {
5136       error ("invalid cast to function type %qT", type);
5137       return error_mark_node;
5138     }
5139
5140   /* A C-style cast can be a const_cast.  */
5141   result = build_const_cast_1 (type, value, /*complain=*/false,
5142                                &valid_p);
5143   if (valid_p)
5144     return result;
5145
5146   /* Or a static cast.  */
5147   result = build_static_cast_1 (type, value, /*c_cast_p=*/true,
5148                                 &valid_p);
5149   /* Or a reinterpret_cast.  */
5150   if (!valid_p)
5151     result = build_reinterpret_cast_1 (type, value, /*c_cast_p=*/true,
5152                                        &valid_p);
5153   /* The static_cast or reinterpret_cast may be followed by a
5154      const_cast.  */
5155   if (valid_p
5156       /* A valid cast may result in errors if, for example, a
5157          conversion to am ambiguous base class is required.  */
5158       && !error_operand_p (result))
5159     {
5160       tree result_type;
5161
5162       /* Non-class rvalues always have cv-unqualified type.  */
5163       if (!CLASS_TYPE_P (type))
5164         type = TYPE_MAIN_VARIANT (type);
5165       result_type = TREE_TYPE (result);
5166       if (!CLASS_TYPE_P (result_type))
5167         result_type = TYPE_MAIN_VARIANT (result_type);
5168       /* If the type of RESULT does not match TYPE, perform a
5169          const_cast to make it match.  If the static_cast or
5170          reinterpret_cast succeeded, we will differ by at most
5171          cv-qualification, so the follow-on const_cast is guaranteed
5172          to succeed.  */
5173       if (!same_type_p (non_reference (type), non_reference (result_type)))
5174         {
5175           result = build_const_cast_1 (type, result, false, &valid_p);
5176           gcc_assert (valid_p);
5177         }
5178       return result;
5179     }
5180
5181   return error_mark_node;
5182 }
5183 \f
5184 /* Build an assignment expression of lvalue LHS from value RHS.
5185    MODIFYCODE is the code for a binary operator that we use
5186    to combine the old value of LHS with RHS to get the new value.
5187    Or else MODIFYCODE is NOP_EXPR meaning do a simple assignment.
5188
5189    C++: If MODIFYCODE is INIT_EXPR, then leave references unbashed.  */
5190
5191 tree
5192 build_modify_expr (tree lhs, enum tree_code modifycode, tree rhs)
5193 {
5194   tree result;
5195   tree newrhs = rhs;
5196   tree lhstype = TREE_TYPE (lhs);
5197   tree olhstype = lhstype;
5198   tree olhs = NULL_TREE;
5199   bool plain_assign = (modifycode == NOP_EXPR);
5200
5201   /* Avoid duplicate error messages from operands that had errors.  */
5202   if (lhs == error_mark_node || rhs == error_mark_node)
5203     return error_mark_node;
5204
5205   /* Handle control structure constructs used as "lvalues".  */
5206   switch (TREE_CODE (lhs))
5207     {
5208       /* Handle --foo = 5; as these are valid constructs in C++.  */
5209     case PREDECREMENT_EXPR:
5210     case PREINCREMENT_EXPR:
5211       if (TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 0)))
5212         lhs = build2 (TREE_CODE (lhs), TREE_TYPE (lhs),
5213                       stabilize_reference (TREE_OPERAND (lhs, 0)),
5214                       TREE_OPERAND (lhs, 1));
5215       return build2 (COMPOUND_EXPR, lhstype,
5216                      lhs,
5217                      build_modify_expr (TREE_OPERAND (lhs, 0),
5218                                         modifycode, rhs));
5219
5220       /* Handle (a, b) used as an "lvalue".  */
5221     case COMPOUND_EXPR:
5222       newrhs = build_modify_expr (TREE_OPERAND (lhs, 1),
5223                                   modifycode, rhs);
5224       if (newrhs == error_mark_node)
5225         return error_mark_node;
5226       return build2 (COMPOUND_EXPR, lhstype,
5227                      TREE_OPERAND (lhs, 0), newrhs);
5228
5229     case MODIFY_EXPR:
5230       if (TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 0)))
5231         lhs = build2 (TREE_CODE (lhs), TREE_TYPE (lhs),
5232                       stabilize_reference (TREE_OPERAND (lhs, 0)),
5233                       TREE_OPERAND (lhs, 1));
5234       newrhs = build_modify_expr (TREE_OPERAND (lhs, 0), modifycode, rhs);
5235       if (newrhs == error_mark_node)
5236         return error_mark_node;
5237       return build2 (COMPOUND_EXPR, lhstype, lhs, newrhs);
5238
5239     case MIN_EXPR:
5240     case MAX_EXPR:
5241       /* MIN_EXPR and MAX_EXPR are currently only permitted as lvalues,
5242          when neither operand has side-effects.  */
5243       if (!lvalue_or_else (lhs, lv_assign))
5244         return error_mark_node;
5245
5246       gcc_assert (!TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 0))
5247                   && !TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 1)));
5248
5249       lhs = build3 (COND_EXPR, TREE_TYPE (lhs),
5250                     build2 (TREE_CODE (lhs) == MIN_EXPR ? LE_EXPR : GE_EXPR,
5251                             boolean_type_node,
5252                             TREE_OPERAND (lhs, 0),
5253                             TREE_OPERAND (lhs, 1)),
5254                     TREE_OPERAND (lhs, 0),
5255                     TREE_OPERAND (lhs, 1));
5256       /* Fall through.  */
5257
5258       /* Handle (a ? b : c) used as an "lvalue".  */
5259     case COND_EXPR:
5260       {
5261         /* Produce (a ? (b = rhs) : (c = rhs))
5262            except that the RHS goes through a save-expr
5263            so the code to compute it is only emitted once.  */
5264         tree cond;
5265         tree preeval = NULL_TREE;
5266
5267         rhs = stabilize_expr (rhs, &preeval);
5268
5269         /* Check this here to avoid odd errors when trying to convert
5270            a throw to the type of the COND_EXPR.  */
5271         if (!lvalue_or_else (lhs, lv_assign))
5272           return error_mark_node;
5273
5274         cond = build_conditional_expr
5275           (TREE_OPERAND (lhs, 0),
5276            build_modify_expr (cp_convert (TREE_TYPE (lhs),
5277                                           TREE_OPERAND (lhs, 1)),
5278                               modifycode, rhs),
5279            build_modify_expr (cp_convert (TREE_TYPE (lhs),
5280                                           TREE_OPERAND (lhs, 2)),
5281                               modifycode, rhs));
5282
5283         if (cond == error_mark_node)
5284           return cond;
5285         /* Make sure the code to compute the rhs comes out
5286            before the split.  */
5287         if (preeval)
5288           cond = build2 (COMPOUND_EXPR, TREE_TYPE (lhs), preeval, cond);
5289         return cond;
5290       }
5291
5292     default:
5293       break;
5294     }
5295
5296   if (modifycode == INIT_EXPR)
5297     {
5298       if (TREE_CODE (rhs) == CONSTRUCTOR)
5299         {
5300           if (! same_type_p (TREE_TYPE (rhs), lhstype))
5301             /* Call convert to generate an error; see PR 11063.  */
5302             rhs = convert (lhstype, rhs);
5303           result = build2 (INIT_EXPR, lhstype, lhs, rhs);
5304           TREE_SIDE_EFFECTS (result) = 1;
5305           return result;
5306         }
5307       else if (! IS_AGGR_TYPE (lhstype))
5308         /* Do the default thing.  */;
5309       else
5310         {
5311           result = build_special_member_call (lhs, complete_ctor_identifier,
5312                                               build_tree_list (NULL_TREE, rhs),
5313                                               lhstype, LOOKUP_NORMAL);
5314           if (result == NULL_TREE)
5315             return error_mark_node;
5316           return result;
5317         }
5318     }
5319   else
5320     {
5321       lhs = require_complete_type (lhs);
5322       if (lhs == error_mark_node)
5323         return error_mark_node;
5324
5325       if (modifycode == NOP_EXPR)
5326         {
5327           /* `operator=' is not an inheritable operator.  */
5328           if (! IS_AGGR_TYPE (lhstype))
5329             /* Do the default thing.  */;
5330           else
5331             {
5332               result = build_new_op (MODIFY_EXPR, LOOKUP_NORMAL,
5333                                      lhs, rhs, make_node (NOP_EXPR),
5334                                      /*overloaded_p=*/NULL);
5335               if (result == NULL_TREE)
5336                 return error_mark_node;
5337               return result;
5338             }
5339           lhstype = olhstype;
5340         }
5341       else
5342         {
5343           /* A binary op has been requested.  Combine the old LHS
5344              value with the RHS producing the value we should actually
5345              store into the LHS.  */
5346
5347           gcc_assert (!PROMOTES_TO_AGGR_TYPE (lhstype, REFERENCE_TYPE));
5348           lhs = stabilize_reference (lhs);
5349           newrhs = cp_build_binary_op (modifycode, lhs, rhs);
5350           if (newrhs == error_mark_node)
5351             {
5352               error ("  in evaluation of %<%Q(%#T, %#T)%>", modifycode,
5353                      TREE_TYPE (lhs), TREE_TYPE (rhs));
5354               return error_mark_node;
5355             }
5356
5357           /* Now it looks like a plain assignment.  */
5358           modifycode = NOP_EXPR;
5359         }
5360       gcc_assert (TREE_CODE (lhstype) != REFERENCE_TYPE);
5361       gcc_assert (TREE_CODE (TREE_TYPE (newrhs)) != REFERENCE_TYPE);
5362     }
5363
5364   /* The left-hand side must be an lvalue.  */
5365   if (!lvalue_or_else (lhs, lv_assign))
5366     return error_mark_node;
5367
5368   /* Warn about modifying something that is `const'.  Don't warn if
5369      this is initialization.  */
5370   if (modifycode != INIT_EXPR
5371       && (TREE_READONLY (lhs) || CP_TYPE_CONST_P (lhstype)
5372           /* Functions are not modifiable, even though they are
5373              lvalues.  */
5374           || TREE_CODE (TREE_TYPE (lhs)) == FUNCTION_TYPE
5375           || TREE_CODE (TREE_TYPE (lhs)) == METHOD_TYPE
5376           /* If it's an aggregate and any field is const, then it is
5377              effectively const.  */
5378           || (CLASS_TYPE_P (lhstype)
5379               && C_TYPE_FIELDS_READONLY (lhstype))))
5380     readonly_error (lhs, "assignment", 0);
5381
5382   /* If storing into a structure or union member, it has probably been
5383      given type `int'.  Compute the type that would go with the actual
5384      amount of storage the member occupies.  */
5385
5386   if (TREE_CODE (lhs) == COMPONENT_REF
5387       && (TREE_CODE (lhstype) == INTEGER_TYPE
5388           || TREE_CODE (lhstype) == REAL_TYPE
5389           || TREE_CODE (lhstype) == ENUMERAL_TYPE))
5390     {
5391       lhstype = TREE_TYPE (get_unwidened (lhs, 0));
5392
5393       /* If storing in a field that is in actuality a short or narrower
5394          than one, we must store in the field in its actual type.  */
5395
5396       if (lhstype != TREE_TYPE (lhs))
5397         {
5398           /* Avoid warnings converting integral types back into enums for
5399              enum bit fields.  */
5400           if (TREE_CODE (lhstype) == INTEGER_TYPE
5401               && TREE_CODE (olhstype) == ENUMERAL_TYPE)
5402             {
5403               if (TREE_SIDE_EFFECTS (lhs))
5404                 lhs = stabilize_reference (lhs);
5405               olhs = lhs;
5406             }
5407           lhs = copy_node (lhs);
5408           TREE_TYPE (lhs) = lhstype;
5409         }
5410     }
5411
5412   /* Convert new value to destination type.  */
5413
5414   if (TREE_CODE (lhstype) == ARRAY_TYPE)
5415     {
5416       int from_array;
5417
5418       if (!same_or_base_type_p (TYPE_MAIN_VARIANT (lhstype),
5419                                 TYPE_MAIN_VARIANT (TREE_TYPE (rhs))))
5420         {
5421           error ("incompatible types in assignment of %qT to %qT",
5422                  TREE_TYPE (rhs), lhstype);
5423           return error_mark_node;
5424         }
5425
5426       /* Allow array assignment in compiler-generated code.  */
5427       if (! DECL_ARTIFICIAL (current_function_decl))
5428         pedwarn ("ISO C++ forbids assignment of arrays");
5429
5430       from_array = TREE_CODE (TREE_TYPE (newrhs)) == ARRAY_TYPE
5431                    ? 1 + (modifycode != INIT_EXPR): 0;
5432       return build_vec_init (lhs, NULL_TREE, newrhs, from_array);
5433     }
5434
5435   if (modifycode == INIT_EXPR)
5436     newrhs = convert_for_initialization (lhs, lhstype, newrhs, LOOKUP_NORMAL,
5437                                          "initialization", NULL_TREE, 0);
5438   else
5439     {
5440       /* Avoid warnings on enum bit fields.  */
5441       if (TREE_CODE (olhstype) == ENUMERAL_TYPE
5442           && TREE_CODE (lhstype) == INTEGER_TYPE)
5443         {
5444           newrhs = convert_for_assignment (olhstype, newrhs, "assignment",
5445                                            NULL_TREE, 0);
5446           newrhs = convert_force (lhstype, newrhs, 0);
5447         }
5448       else
5449         newrhs = convert_for_assignment (lhstype, newrhs, "assignment",
5450                                          NULL_TREE, 0);
5451       if (TREE_CODE (newrhs) == CALL_EXPR
5452           && TYPE_NEEDS_CONSTRUCTING (lhstype))
5453         newrhs = build_cplus_new (lhstype, newrhs);
5454
5455       /* Can't initialize directly from a TARGET_EXPR, since that would
5456          cause the lhs to be constructed twice, and possibly result in
5457          accidental self-initialization.  So we force the TARGET_EXPR to be
5458          expanded without a target.  */
5459       if (TREE_CODE (newrhs) == TARGET_EXPR)
5460         newrhs = build2 (COMPOUND_EXPR, TREE_TYPE (newrhs), newrhs,
5461                          TREE_OPERAND (newrhs, 0));
5462     }
5463
5464   if (newrhs == error_mark_node)
5465     return error_mark_node;
5466
5467   result = build2 (modifycode == NOP_EXPR ? MODIFY_EXPR : INIT_EXPR,
5468                    lhstype, lhs, newrhs);
5469
5470   TREE_SIDE_EFFECTS (result) = 1;
5471   if (!plain_assign)
5472     TREE_NO_WARNING (result) = 1;
5473
5474   /* If we got the LHS in a different type for storing in,
5475      convert the result back to the nominal type of LHS
5476      so that the value we return always has the same type
5477      as the LHS argument.  */
5478
5479   if (olhstype == TREE_TYPE (result))
5480     return result;
5481   if (olhs)
5482     {
5483       result = build2 (COMPOUND_EXPR, olhstype, result, olhs);
5484       TREE_NO_WARNING (result) = 1;
5485       return result;
5486     }
5487   return convert_for_assignment (olhstype, result, "assignment",
5488                                  NULL_TREE, 0);
5489 }
5490
5491 tree
5492 build_x_modify_expr (tree lhs, enum tree_code modifycode, tree rhs)
5493 {
5494   if (processing_template_decl)
5495     return build_min_nt (MODOP_EXPR, lhs,
5496                          build_min_nt (modifycode, NULL_TREE, NULL_TREE), rhs);
5497
5498   if (modifycode != NOP_EXPR)
5499     {
5500       tree rval = build_new_op (MODIFY_EXPR, LOOKUP_NORMAL, lhs, rhs,
5501                                 make_node (modifycode),
5502                                 /*overloaded_p=*/NULL);
5503       if (rval)
5504         {
5505           TREE_NO_WARNING (rval) = 1;
5506           return rval;
5507         }
5508     }
5509   return build_modify_expr (lhs, modifycode, rhs);
5510 }
5511
5512 \f
5513 /* Get difference in deltas for different pointer to member function
5514    types.  Returns an integer constant of type PTRDIFF_TYPE_NODE.  If
5515    the conversion is invalid, the constant is zero.  If
5516    ALLOW_INVERSE_P is true, then allow reverse conversions as well.
5517    If C_CAST_P is true this conversion is taking place as part of a
5518    C-style cast.
5519
5520    Note that the naming of FROM and TO is kind of backwards; the return
5521    value is what we add to a TO in order to get a FROM.  They are named
5522    this way because we call this function to find out how to convert from
5523    a pointer to member of FROM to a pointer to member of TO.  */
5524
5525 static tree
5526 get_delta_difference (tree from, tree to,
5527                       bool allow_inverse_p,
5528                       bool c_cast_p)
5529 {
5530   tree binfo;
5531   tree virt_binfo;
5532   base_kind kind;
5533   tree result;
5534
5535   /* Assume no conversion is required.  */
5536   result = integer_zero_node;
5537   binfo = lookup_base (to, from, c_cast_p ? ba_unique : ba_check, &kind);
5538   if (kind == bk_inaccessible || kind == bk_ambig)
5539     error ("   in pointer to member function conversion");
5540   else if (!binfo)
5541     {
5542       if (!allow_inverse_p)
5543         {
5544           error_not_base_type (from, to);
5545           error ("   in pointer to member conversion");
5546         }
5547       else
5548         {
5549           binfo = lookup_base (from, to, c_cast_p ? ba_unique : ba_check,
5550                                &kind);
5551           if (binfo)
5552             {
5553               virt_binfo = binfo_from_vbase (binfo);
5554               if (virt_binfo)
5555                 /* This is a reinterpret cast, we choose to do nothing.  */
5556                 warning ("pointer to member cast via virtual base %qT",
5557                          BINFO_TYPE (virt_binfo));
5558               else
5559                 result = size_diffop (size_zero_node, BINFO_OFFSET (binfo));
5560             }
5561         }
5562     }
5563   else
5564     {
5565       virt_binfo = binfo_from_vbase (binfo);
5566       if (!virt_binfo)
5567         result = BINFO_OFFSET (binfo);
5568       else
5569         {
5570           /* This is a reinterpret cast, we choose to do nothing.  */
5571           if (allow_inverse_p)
5572             warning ("pointer to member cast via virtual base %qT",
5573                      BINFO_TYPE (virt_binfo));
5574           else
5575             error ("pointer to member conversion via virtual base %qT",
5576                    BINFO_TYPE (virt_binfo));
5577         }
5578     }
5579
5580   return fold_if_not_in_template (convert_to_integer (ptrdiff_type_node,
5581                                                       result));
5582 }
5583
5584 /* Return a constructor for the pointer-to-member-function TYPE using
5585    the other components as specified.  */
5586
5587 tree
5588 build_ptrmemfunc1 (tree type, tree delta, tree pfn)
5589 {
5590   tree u = NULL_TREE;
5591   tree delta_field;
5592   tree pfn_field;
5593
5594   /* Pull the FIELD_DECLs out of the type.  */
5595   pfn_field = TYPE_FIELDS (type);
5596   delta_field = TREE_CHAIN (pfn_field);
5597
5598   /* Make sure DELTA has the type we want.  */
5599   delta = convert_and_check (delta_type_node, delta);
5600
5601   /* Finish creating the initializer.  */
5602   u = tree_cons (pfn_field, pfn,
5603                  build_tree_list (delta_field, delta));
5604   u = build_constructor (type, u);
5605   TREE_CONSTANT (u) = TREE_CONSTANT (pfn) & TREE_CONSTANT (delta);
5606   TREE_INVARIANT (u) = TREE_INVARIANT (pfn) & TREE_INVARIANT (delta);
5607   TREE_STATIC (u) = (TREE_CONSTANT (u)
5608                      && (initializer_constant_valid_p (pfn, TREE_TYPE (pfn))
5609                          != NULL_TREE)
5610                      && (initializer_constant_valid_p (delta, TREE_TYPE (delta))
5611                          != NULL_TREE));
5612   return u;
5613 }
5614
5615 /* Build a constructor for a pointer to member function.  It can be
5616    used to initialize global variables, local variable, or used
5617    as a value in expressions.  TYPE is the POINTER to METHOD_TYPE we
5618    want to be.
5619
5620    If FORCE is nonzero, then force this conversion, even if
5621    we would rather not do it.  Usually set when using an explicit
5622    cast.  A C-style cast is being processed iff C_CAST_P is true.
5623
5624    Return error_mark_node, if something goes wrong.  */
5625
5626 tree
5627 build_ptrmemfunc (tree type, tree pfn, int force, bool c_cast_p)
5628 {
5629   tree fn;
5630   tree pfn_type;
5631   tree to_type;
5632
5633   if (error_operand_p (pfn))
5634     return error_mark_node;
5635
5636   pfn_type = TREE_TYPE (pfn);
5637   to_type = build_ptrmemfunc_type (type);
5638
5639   /* Handle multiple conversions of pointer to member functions.  */
5640   if (TYPE_PTRMEMFUNC_P (pfn_type))
5641     {
5642       tree delta = NULL_TREE;
5643       tree npfn = NULL_TREE;
5644       tree n;
5645
5646       if (!force
5647           && !can_convert_arg (to_type, TREE_TYPE (pfn), pfn))
5648         error ("invalid conversion to type %qT from type %qT",
5649                to_type, pfn_type);
5650
5651       n = get_delta_difference (TYPE_PTRMEMFUNC_OBJECT_TYPE (pfn_type),
5652                                 TYPE_PTRMEMFUNC_OBJECT_TYPE (to_type),
5653                                 force,
5654                                 c_cast_p);
5655
5656       /* We don't have to do any conversion to convert a
5657          pointer-to-member to its own type.  But, we don't want to
5658          just return a PTRMEM_CST if there's an explicit cast; that
5659          cast should make the expression an invalid template argument.  */
5660       if (TREE_CODE (pfn) != PTRMEM_CST)
5661         {
5662           if (same_type_p (to_type, pfn_type))
5663             return pfn;
5664           else if (integer_zerop (n))
5665             return build_reinterpret_cast (to_type, pfn);
5666         }
5667
5668       if (TREE_SIDE_EFFECTS (pfn))
5669         pfn = save_expr (pfn);
5670
5671       /* Obtain the function pointer and the current DELTA.  */
5672       if (TREE_CODE (pfn) == PTRMEM_CST)
5673         expand_ptrmemfunc_cst (pfn, &delta, &npfn);
5674       else
5675         {
5676           npfn = build_ptrmemfunc_access_expr (pfn, pfn_identifier);
5677           delta = build_ptrmemfunc_access_expr (pfn, delta_identifier);
5678         }
5679
5680       /* Just adjust the DELTA field.  */
5681       gcc_assert  (same_type_ignoring_top_level_qualifiers_p
5682                    (TREE_TYPE (delta), ptrdiff_type_node));
5683       if (TARGET_PTRMEMFUNC_VBIT_LOCATION == ptrmemfunc_vbit_in_delta)
5684         n = cp_build_binary_op (LSHIFT_EXPR, n, integer_one_node);
5685       delta = cp_build_binary_op (PLUS_EXPR, delta, n);
5686       return build_ptrmemfunc1 (to_type, delta, npfn);
5687     }
5688
5689   /* Handle null pointer to member function conversions.  */
5690   if (integer_zerop (pfn))
5691     {
5692       pfn = build_c_cast (type, integer_zero_node);
5693       return build_ptrmemfunc1 (to_type,
5694                                 integer_zero_node,
5695                                 pfn);
5696     }
5697
5698   if (type_unknown_p (pfn))
5699     return instantiate_type (type, pfn, tf_error | tf_warning);
5700
5701   fn = TREE_OPERAND (pfn, 0);
5702   gcc_assert (TREE_CODE (fn) == FUNCTION_DECL
5703               /* In a template, we will have preserved the
5704                  OFFSET_REF.  */
5705               || (processing_template_decl && TREE_CODE (fn) == OFFSET_REF));
5706   return make_ptrmem_cst (to_type, fn);
5707 }
5708
5709 /* Return the DELTA, IDX, PFN, and DELTA2 values for the PTRMEM_CST
5710    given by CST.
5711
5712    ??? There is no consistency as to the types returned for the above
5713    values.  Some code acts as if it were a sizetype and some as if it were
5714    integer_type_node.  */
5715
5716 void
5717 expand_ptrmemfunc_cst (tree cst, tree *delta, tree *pfn)
5718 {
5719   tree type = TREE_TYPE (cst);
5720   tree fn = PTRMEM_CST_MEMBER (cst);
5721   tree ptr_class, fn_class;
5722
5723   gcc_assert (TREE_CODE (fn) == FUNCTION_DECL);
5724
5725   /* The class that the function belongs to.  */
5726   fn_class = DECL_CONTEXT (fn);
5727
5728   /* The class that we're creating a pointer to member of.  */
5729   ptr_class = TYPE_PTRMEMFUNC_OBJECT_TYPE (type);
5730
5731   /* First, calculate the adjustment to the function's class.  */
5732   *delta = get_delta_difference (fn_class, ptr_class, /*force=*/0,
5733                                  /*c_cast_p=*/0);
5734
5735   if (!DECL_VIRTUAL_P (fn))
5736     *pfn = convert (TYPE_PTRMEMFUNC_FN_TYPE (type), build_addr_func (fn));
5737   else
5738     {
5739       /* If we're dealing with a virtual function, we have to adjust 'this'
5740          again, to point to the base which provides the vtable entry for
5741          fn; the call will do the opposite adjustment.  */
5742       tree orig_class = DECL_CONTEXT (fn);
5743       tree binfo = binfo_or_else (orig_class, fn_class);
5744       *delta = build2 (PLUS_EXPR, TREE_TYPE (*delta),
5745                        *delta, BINFO_OFFSET (binfo));
5746       *delta = fold_if_not_in_template (*delta);
5747
5748       /* We set PFN to the vtable offset at which the function can be
5749          found, plus one (unless ptrmemfunc_vbit_in_delta, in which
5750          case delta is shifted left, and then incremented).  */
5751       *pfn = DECL_VINDEX (fn);
5752       *pfn = build2 (MULT_EXPR, integer_type_node, *pfn,
5753                      TYPE_SIZE_UNIT (vtable_entry_type));
5754       *pfn = fold_if_not_in_template (*pfn);
5755
5756       switch (TARGET_PTRMEMFUNC_VBIT_LOCATION)
5757         {
5758         case ptrmemfunc_vbit_in_pfn:
5759           *pfn = build2 (PLUS_EXPR, integer_type_node, *pfn,
5760                          integer_one_node);
5761           *pfn = fold_if_not_in_template (*pfn);
5762           break;
5763
5764         case ptrmemfunc_vbit_in_delta:
5765           *delta = build2 (LSHIFT_EXPR, TREE_TYPE (*delta),
5766                            *delta, integer_one_node);
5767           *delta = fold_if_not_in_template (*delta);
5768           *delta = build2 (PLUS_EXPR, TREE_TYPE (*delta),
5769                            *delta, integer_one_node);
5770           *delta = fold_if_not_in_template (*delta);
5771           break;
5772
5773         default:
5774           gcc_unreachable ();
5775         }
5776
5777       *pfn = build_nop (TYPE_PTRMEMFUNC_FN_TYPE (type), *pfn);
5778       *pfn = fold_if_not_in_template (*pfn);
5779     }
5780 }
5781
5782 /* Return an expression for PFN from the pointer-to-member function
5783    given by T.  */
5784
5785 tree
5786 pfn_from_ptrmemfunc (tree t)
5787 {
5788   if (TREE_CODE (t) == PTRMEM_CST)
5789     {
5790       tree delta;
5791       tree pfn;
5792
5793       expand_ptrmemfunc_cst (t, &delta, &pfn);
5794       if (pfn)
5795         return pfn;
5796     }
5797
5798   return build_ptrmemfunc_access_expr (t, pfn_identifier);
5799 }
5800
5801 /* Convert value RHS to type TYPE as preparation for an assignment to
5802    an lvalue of type TYPE.  ERRTYPE is a string to use in error
5803    messages: "assignment", "return", etc.  If FNDECL is non-NULL, we
5804    are doing the conversion in order to pass the PARMNUMth argument of
5805    FNDECL.  */
5806
5807 static tree
5808 convert_for_assignment (tree type, tree rhs,
5809                         const char *errtype, tree fndecl, int parmnum)
5810 {
5811   tree rhstype;
5812   enum tree_code coder;
5813
5814   /* Strip NON_LVALUE_EXPRs since we aren't using as an lvalue.  */
5815   if (TREE_CODE (rhs) == NON_LVALUE_EXPR)
5816     rhs = TREE_OPERAND (rhs, 0);
5817
5818   rhstype = TREE_TYPE (rhs);
5819   coder = TREE_CODE (rhstype);
5820
5821   if (TREE_CODE (type) == VECTOR_TYPE && coder == VECTOR_TYPE
5822       && vector_types_convertible_p (type, rhstype))
5823     return convert (type, rhs);
5824
5825   if (rhs == error_mark_node || rhstype == error_mark_node)
5826     return error_mark_node;
5827   if (TREE_CODE (rhs) == TREE_LIST && TREE_VALUE (rhs) == error_mark_node)
5828     return error_mark_node;
5829
5830   /* The RHS of an assignment cannot have void type.  */
5831   if (coder == VOID_TYPE)
5832     {
5833       error ("void value not ignored as it ought to be");
5834       return error_mark_node;
5835     }
5836
5837   /* Simplify the RHS if possible.  */
5838   if (TREE_CODE (rhs) == CONST_DECL)
5839     rhs = DECL_INITIAL (rhs);
5840
5841   /* [expr.ass]
5842
5843      The expression is implicitly converted (clause _conv_) to the
5844      cv-unqualified type of the left operand.
5845
5846      We allow bad conversions here because by the time we get to this point
5847      we are committed to doing the conversion.  If we end up doing a bad
5848      conversion, convert_like will complain.  */
5849   if (!can_convert_arg_bad (type, rhstype, rhs))
5850     {
5851       /* When -Wno-pmf-conversions is use, we just silently allow
5852          conversions from pointers-to-members to plain pointers.  If
5853          the conversion doesn't work, cp_convert will complain.  */
5854       if (!warn_pmf2ptr
5855           && TYPE_PTR_P (type)
5856           && TYPE_PTRMEMFUNC_P (rhstype))
5857         rhs = cp_convert (strip_top_quals (type), rhs);
5858       else
5859         {
5860           /* If the right-hand side has unknown type, then it is an
5861              overloaded function.  Call instantiate_type to get error
5862              messages.  */
5863           if (rhstype == unknown_type_node)
5864             instantiate_type (type, rhs, tf_error | tf_warning);
5865           else if (fndecl)
5866             error ("cannot convert %qT to %qT for argument %qP to %qD",
5867                    rhstype, type, parmnum, fndecl);
5868           else
5869             error ("cannot convert %qT to %qT in %s", rhstype, type, errtype);
5870           return error_mark_node;
5871         }
5872     }
5873   return perform_implicit_conversion (strip_top_quals (type), rhs);
5874 }
5875
5876 /* Convert RHS to be of type TYPE.
5877    If EXP is nonzero, it is the target of the initialization.
5878    ERRTYPE is a string to use in error messages.
5879
5880    Two major differences between the behavior of
5881    `convert_for_assignment' and `convert_for_initialization'
5882    are that references are bashed in the former, while
5883    copied in the latter, and aggregates are assigned in
5884    the former (operator=) while initialized in the
5885    latter (X(X&)).
5886
5887    If using constructor make sure no conversion operator exists, if one does
5888    exist, an ambiguity exists.
5889
5890    If flags doesn't include LOOKUP_COMPLAIN, don't complain about anything.  */
5891
5892 tree
5893 convert_for_initialization (tree exp, tree type, tree rhs, int flags,
5894                             const char *errtype, tree fndecl, int parmnum)
5895 {
5896   enum tree_code codel = TREE_CODE (type);
5897   tree rhstype;
5898   enum tree_code coder;
5899
5900   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
5901      Strip such NOP_EXPRs, since RHS is used in non-lvalue context.  */
5902   if (TREE_CODE (rhs) == NOP_EXPR
5903       && TREE_TYPE (rhs) == TREE_TYPE (TREE_OPERAND (rhs, 0))
5904       && codel != REFERENCE_TYPE)
5905     rhs = TREE_OPERAND (rhs, 0);
5906
5907   if (rhs == error_mark_node
5908       || (TREE_CODE (rhs) == TREE_LIST && TREE_VALUE (rhs) == error_mark_node))
5909     return error_mark_node;
5910
5911   if ((TREE_CODE (TREE_TYPE (rhs)) == ARRAY_TYPE
5912        && TREE_CODE (type) != ARRAY_TYPE
5913        && (TREE_CODE (type) != REFERENCE_TYPE
5914            || TREE_CODE (TREE_TYPE (type)) != ARRAY_TYPE))
5915       || (TREE_CODE (TREE_TYPE (rhs)) == FUNCTION_TYPE
5916           && (TREE_CODE (type) != REFERENCE_TYPE
5917               || TREE_CODE (TREE_TYPE (type)) != FUNCTION_TYPE))
5918       || TREE_CODE (TREE_TYPE (rhs)) == METHOD_TYPE)
5919     rhs = decay_conversion (rhs);
5920
5921   rhstype = TREE_TYPE (rhs);
5922   coder = TREE_CODE (rhstype);
5923
5924   if (coder == ERROR_MARK)
5925     return error_mark_node;
5926
5927   /* We accept references to incomplete types, so we can
5928      return here before checking if RHS is of complete type.  */
5929
5930   if (codel == REFERENCE_TYPE)
5931     {
5932       /* This should eventually happen in convert_arguments.  */
5933       int savew = 0, savee = 0;
5934
5935       if (fndecl)
5936         savew = warningcount, savee = errorcount;
5937       rhs = initialize_reference (type, rhs, /*decl=*/NULL_TREE,
5938                                   /*cleanup=*/NULL);
5939       if (fndecl)
5940         {
5941           if (warningcount > savew)
5942             cp_warning_at ("in passing argument %P of %q+D", parmnum, fndecl);
5943           else if (errorcount > savee)
5944             cp_error_at ("in passing argument %P of %q+D", parmnum, fndecl);
5945         }
5946       return rhs;
5947     }
5948
5949   if (exp != 0)
5950     exp = require_complete_type (exp);
5951   if (exp == error_mark_node)
5952     return error_mark_node;
5953
5954   rhstype = non_reference (rhstype);
5955
5956   type = complete_type (type);
5957
5958   if (IS_AGGR_TYPE (type))
5959     return ocp_convert (type, rhs, CONV_IMPLICIT|CONV_FORCE_TEMP, flags);
5960
5961   return convert_for_assignment (type, rhs, errtype, fndecl, parmnum);
5962 }
5963 \f
5964 /* If RETVAL is the address of, or a reference to, a local variable or
5965    temporary give an appropriate warning.  */
5966
5967 static void
5968 maybe_warn_about_returning_address_of_local (tree retval)
5969 {
5970   tree valtype = TREE_TYPE (DECL_RESULT (current_function_decl));
5971   tree whats_returned = retval;
5972
5973   for (;;)
5974     {
5975       if (TREE_CODE (whats_returned) == COMPOUND_EXPR)
5976         whats_returned = TREE_OPERAND (whats_returned, 1);
5977       else if (TREE_CODE (whats_returned) == CONVERT_EXPR
5978                || TREE_CODE (whats_returned) == NON_LVALUE_EXPR
5979                || TREE_CODE (whats_returned) == NOP_EXPR)
5980         whats_returned = TREE_OPERAND (whats_returned, 0);
5981       else
5982         break;
5983     }
5984
5985   if (TREE_CODE (whats_returned) != ADDR_EXPR)
5986     return;
5987   whats_returned = TREE_OPERAND (whats_returned, 0);
5988
5989   if (TREE_CODE (valtype) == REFERENCE_TYPE)
5990     {
5991       if (TREE_CODE (whats_returned) == AGGR_INIT_EXPR
5992           || TREE_CODE (whats_returned) == TARGET_EXPR)
5993         {
5994           warning ("returning reference to temporary");
5995           return;
5996         }
5997       if (TREE_CODE (whats_returned) == VAR_DECL
5998           && DECL_NAME (whats_returned)
5999           && TEMP_NAME_P (DECL_NAME (whats_returned)))
6000         {
6001           warning ("reference to non-lvalue returned");
6002           return;
6003         }
6004     }
6005
6006   if (DECL_P (whats_returned)
6007       && DECL_NAME (whats_returned)
6008       && DECL_FUNCTION_SCOPE_P (whats_returned)
6009       && !(TREE_STATIC (whats_returned)
6010            || TREE_PUBLIC (whats_returned)))
6011     {
6012       if (TREE_CODE (valtype) == REFERENCE_TYPE)
6013         cp_warning_at ("reference to local variable %qD returned",
6014                        whats_returned);
6015       else
6016         cp_warning_at ("address of local variable %qD returned",
6017                        whats_returned);
6018       return;
6019     }
6020 }
6021
6022 /* Check that returning RETVAL from the current function is valid.
6023    Return an expression explicitly showing all conversions required to
6024    change RETVAL into the function return type, and to assign it to
6025    the DECL_RESULT for the function.  */
6026
6027 tree
6028 check_return_expr (tree retval)
6029 {
6030   tree result;
6031   /* The type actually returned by the function, after any
6032      promotions.  */
6033   tree valtype;
6034   int fn_returns_value_p;
6035
6036   /* A `volatile' function is one that isn't supposed to return, ever.
6037      (This is a G++ extension, used to get better code for functions
6038      that call the `volatile' function.)  */
6039   if (TREE_THIS_VOLATILE (current_function_decl))
6040     warning ("function declared %<noreturn%> has a %<return%> statement");
6041
6042   /* Check for various simple errors.  */
6043   if (DECL_DESTRUCTOR_P (current_function_decl))
6044     {
6045       if (retval)
6046         error ("returning a value from a destructor");
6047       return NULL_TREE;
6048     }
6049   else if (DECL_CONSTRUCTOR_P (current_function_decl))
6050     {
6051       if (in_function_try_handler)
6052         /* If a return statement appears in a handler of the
6053            function-try-block of a constructor, the program is ill-formed.  */
6054         error ("cannot return from a handler of a function-try-block of a constructor");
6055       else if (retval)
6056         /* You can't return a value from a constructor.  */
6057         error ("returning a value from a constructor");
6058       return NULL_TREE;
6059     }
6060
6061   if (processing_template_decl)
6062     {
6063       current_function_returns_value = 1;
6064       return retval;
6065     }
6066
6067   /* When no explicit return-value is given in a function with a named
6068      return value, the named return value is used.  */
6069   result = DECL_RESULT (current_function_decl);
6070   valtype = TREE_TYPE (result);
6071   gcc_assert (valtype != NULL_TREE);
6072   fn_returns_value_p = !VOID_TYPE_P (valtype);
6073   if (!retval && DECL_NAME (result) && fn_returns_value_p)
6074     retval = result;
6075
6076   /* Check for a return statement with no return value in a function
6077      that's supposed to return a value.  */
6078   if (!retval && fn_returns_value_p)
6079     {
6080       pedwarn ("return-statement with no value, in function returning %qT",
6081                valtype);
6082       /* Clear this, so finish_function won't say that we reach the
6083          end of a non-void function (which we don't, we gave a
6084          return!).  */
6085       current_function_returns_null = 0;
6086     }
6087   /* Check for a return statement with a value in a function that
6088      isn't supposed to return a value.  */
6089   else if (retval && !fn_returns_value_p)
6090     {
6091       if (VOID_TYPE_P (TREE_TYPE (retval)))
6092         /* You can return a `void' value from a function of `void'
6093            type.  In that case, we have to evaluate the expression for
6094            its side-effects.  */
6095           finish_expr_stmt (retval);
6096       else
6097         pedwarn ("return-statement with a value, in function "
6098                  "returning 'void'");
6099
6100       current_function_returns_null = 1;
6101
6102       /* There's really no value to return, after all.  */
6103       return NULL_TREE;
6104     }
6105   else if (!retval)
6106     /* Remember that this function can sometimes return without a
6107        value.  */
6108     current_function_returns_null = 1;
6109   else
6110     /* Remember that this function did return a value.  */
6111     current_function_returns_value = 1;
6112
6113   /* Check for erroneous operands -- but after giving ourselves a
6114      chance to provide an error about returning a value from a void
6115      function.  */
6116   if (error_operand_p (retval))
6117     {
6118       current_function_return_value = error_mark_node;
6119       return error_mark_node;
6120     }
6121
6122   /* Only operator new(...) throw(), can return NULL [expr.new/13].  */
6123   if ((DECL_OVERLOADED_OPERATOR_P (current_function_decl) == NEW_EXPR
6124        || DECL_OVERLOADED_OPERATOR_P (current_function_decl) == VEC_NEW_EXPR)
6125       && !TYPE_NOTHROW_P (TREE_TYPE (current_function_decl))
6126       && ! flag_check_new
6127       && null_ptr_cst_p (retval))
6128     warning ("%<operator new%> must not return NULL unless it is "
6129              "declared %<throw()%> (or -fcheck-new is in effect)");
6130
6131   /* Effective C++ rule 15.  See also start_function.  */
6132   if (warn_ecpp
6133       && DECL_NAME (current_function_decl) == ansi_assopname(NOP_EXPR))
6134     {
6135       bool warn = true;
6136
6137       /* The function return type must be a reference to the current
6138         class.  */
6139       if (TREE_CODE (valtype) == REFERENCE_TYPE
6140           && same_type_ignoring_top_level_qualifiers_p
6141               (TREE_TYPE (valtype), TREE_TYPE (current_class_ref)))
6142         {
6143           /* Returning '*this' is obviously OK.  */
6144           if (retval == current_class_ref)
6145             warn = false;
6146           /* If we are calling a function whose return type is the same of
6147              the current class reference, it is ok.  */
6148           else if (TREE_CODE (retval) == INDIRECT_REF
6149                    && TREE_CODE (TREE_OPERAND (retval, 0)) == CALL_EXPR)
6150             warn = false;
6151         }
6152
6153       if (warn)
6154         warning ("%<operator=%> should return a reference to %<*this%>");
6155     }
6156
6157   /* The fabled Named Return Value optimization, as per [class.copy]/15:
6158
6159      [...]      For  a function with a class return type, if the expression
6160      in the return statement is the name of a local  object,  and  the  cv-
6161      unqualified  type  of  the  local  object  is the same as the function
6162      return type, an implementation is permitted to omit creating the  tem-
6163      porary  object  to  hold  the function return value [...]
6164
6165      So, if this is a value-returning function that always returns the same
6166      local variable, remember it.
6167
6168      It might be nice to be more flexible, and choose the first suitable
6169      variable even if the function sometimes returns something else, but
6170      then we run the risk of clobbering the variable we chose if the other
6171      returned expression uses the chosen variable somehow.  And people expect
6172      this restriction, anyway.  (jason 2000-11-19)
6173
6174      See finish_function and finalize_nrv for the rest of this optimization.  */
6175
6176   if (fn_returns_value_p && flag_elide_constructors)
6177     {
6178       if (retval != NULL_TREE
6179           && (current_function_return_value == NULL_TREE
6180               || current_function_return_value == retval)
6181           && TREE_CODE (retval) == VAR_DECL
6182           && DECL_CONTEXT (retval) == current_function_decl
6183           && ! TREE_STATIC (retval)
6184           && (DECL_ALIGN (retval)
6185               >= DECL_ALIGN (DECL_RESULT (current_function_decl)))
6186           && same_type_p ((TYPE_MAIN_VARIANT
6187                            (TREE_TYPE (retval))),
6188                           (TYPE_MAIN_VARIANT
6189                            (TREE_TYPE (TREE_TYPE (current_function_decl))))))
6190         current_function_return_value = retval;
6191       else
6192         current_function_return_value = error_mark_node;
6193     }
6194
6195   /* We don't need to do any conversions when there's nothing being
6196      returned.  */
6197   if (!retval)
6198     return NULL_TREE;
6199
6200   /* Do any required conversions.  */
6201   if (retval == result || DECL_CONSTRUCTOR_P (current_function_decl))
6202     /* No conversions are required.  */
6203     ;
6204   else
6205     {
6206       /* The type the function is declared to return.  */
6207       tree functype = TREE_TYPE (TREE_TYPE (current_function_decl));
6208
6209       /* First convert the value to the function's return type, then
6210          to the type of return value's location to handle the
6211          case that functype is smaller than the valtype.  */
6212       retval = convert_for_initialization
6213         (NULL_TREE, functype, retval, LOOKUP_NORMAL|LOOKUP_ONLYCONVERTING,
6214          "return", NULL_TREE, 0);
6215       retval = convert (valtype, retval);
6216
6217       /* If the conversion failed, treat this just like `return;'.  */
6218       if (retval == error_mark_node)
6219         return retval;
6220       /* We can't initialize a register from a AGGR_INIT_EXPR.  */
6221       else if (! current_function_returns_struct
6222                && TREE_CODE (retval) == TARGET_EXPR
6223                && TREE_CODE (TREE_OPERAND (retval, 1)) == AGGR_INIT_EXPR)
6224         retval = build2 (COMPOUND_EXPR, TREE_TYPE (retval), retval,
6225                          TREE_OPERAND (retval, 0));
6226       else
6227         maybe_warn_about_returning_address_of_local (retval);
6228     }
6229
6230   /* Actually copy the value returned into the appropriate location.  */
6231   if (retval && retval != result)
6232     retval = build2 (INIT_EXPR, TREE_TYPE (result), result, retval);
6233
6234   return retval;
6235 }
6236
6237 \f
6238 /* Returns nonzero if the pointer-type FROM can be converted to the
6239    pointer-type TO via a qualification conversion.  If CONSTP is -1,
6240    then we return nonzero if the pointers are similar, and the
6241    cv-qualification signature of FROM is a proper subset of that of TO.
6242
6243    If CONSTP is positive, then all outer pointers have been
6244    const-qualified.  */
6245
6246 static int
6247 comp_ptr_ttypes_real (tree to, tree from, int constp)
6248 {
6249   bool to_more_cv_qualified = false;
6250
6251   for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
6252     {
6253       if (TREE_CODE (to) != TREE_CODE (from))
6254         return 0;
6255
6256       if (TREE_CODE (from) == OFFSET_TYPE
6257           && !same_type_p (TYPE_OFFSET_BASETYPE (from),
6258                            TYPE_OFFSET_BASETYPE (to)))
6259         return 0;
6260
6261       /* Const and volatile mean something different for function types,
6262          so the usual checks are not appropriate.  */
6263       if (TREE_CODE (to) != FUNCTION_TYPE && TREE_CODE (to) != METHOD_TYPE)
6264         {
6265           if (!at_least_as_qualified_p (to, from))
6266             return 0;
6267
6268           if (!at_least_as_qualified_p (from, to))
6269             {
6270               if (constp == 0)
6271                 return 0;
6272               to_more_cv_qualified = true;
6273             }
6274
6275           if (constp > 0)
6276             constp &= TYPE_READONLY (to);
6277         }
6278
6279       if (TREE_CODE (to) != POINTER_TYPE && !TYPE_PTRMEM_P (to))
6280         return ((constp >= 0 || to_more_cv_qualified)
6281                 && same_type_ignoring_top_level_qualifiers_p (to, from));
6282     }
6283 }
6284
6285 /* When comparing, say, char ** to char const **, this function takes
6286    the 'char *' and 'char const *'.  Do not pass non-pointer/reference
6287    types to this function.  */
6288
6289 int
6290 comp_ptr_ttypes (tree to, tree from)
6291 {
6292   return comp_ptr_ttypes_real (to, from, 1);
6293 }
6294
6295 /* Returns 1 if to and from are (possibly multi-level) pointers to the same
6296    type or inheritance-related types, regardless of cv-quals.  */
6297
6298 int
6299 ptr_reasonably_similar (tree to, tree from)
6300 {
6301   for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
6302     {
6303       /* Any target type is similar enough to void.  */
6304       if (TREE_CODE (to) == VOID_TYPE
6305           || TREE_CODE (from) == VOID_TYPE)
6306         return 1;
6307
6308       if (TREE_CODE (to) != TREE_CODE (from))
6309         return 0;
6310
6311       if (TREE_CODE (from) == OFFSET_TYPE
6312           && comptypes (TYPE_OFFSET_BASETYPE (to),
6313                         TYPE_OFFSET_BASETYPE (from),
6314                         COMPARE_BASE | COMPARE_DERIVED))
6315         continue;
6316
6317       if (TREE_CODE (to) == VECTOR_TYPE
6318           && vector_types_convertible_p (to, from))
6319         return 1;
6320
6321       if (TREE_CODE (to) == INTEGER_TYPE
6322           && TYPE_PRECISION (to) == TYPE_PRECISION (from))
6323         return 1;
6324
6325       if (TREE_CODE (to) == FUNCTION_TYPE)
6326         return 1;
6327
6328       if (TREE_CODE (to) != POINTER_TYPE)
6329         return comptypes
6330           (TYPE_MAIN_VARIANT (to), TYPE_MAIN_VARIANT (from),
6331            COMPARE_BASE | COMPARE_DERIVED);
6332     }
6333 }
6334
6335 /* Like comp_ptr_ttypes, for const_cast.  */
6336
6337 static int
6338 comp_ptr_ttypes_const (tree to, tree from)
6339 {
6340   for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
6341     {
6342       if (TREE_CODE (to) != TREE_CODE (from))
6343         return 0;
6344
6345       if (TREE_CODE (from) == OFFSET_TYPE
6346           && same_type_p (TYPE_OFFSET_BASETYPE (from),
6347                           TYPE_OFFSET_BASETYPE (to)))
6348           continue;
6349
6350       if (TREE_CODE (to) != POINTER_TYPE)
6351         return same_type_ignoring_top_level_qualifiers_p (to, from);
6352     }
6353 }
6354
6355 /* Returns the type qualifiers for this type, including the qualifiers on the
6356    elements for an array type.  */
6357
6358 int
6359 cp_type_quals (tree type)
6360 {
6361   type = strip_array_types (type);
6362   if (type == error_mark_node)
6363     return TYPE_UNQUALIFIED;
6364   return TYPE_QUALS (type);
6365 }
6366
6367 /* Returns nonzero if the TYPE contains a mutable member.  */
6368
6369 bool
6370 cp_has_mutable_p (tree type)
6371 {
6372   type = strip_array_types (type);
6373
6374   return CLASS_TYPE_P (type) && CLASSTYPE_HAS_MUTABLE (type);
6375 }
6376
6377 /* Apply the TYPE_QUALS to the new DECL.  */
6378 void
6379 cp_apply_type_quals_to_decl (int type_quals, tree decl)
6380 {
6381   tree type = TREE_TYPE (decl);
6382
6383   if (type == error_mark_node)
6384     return;
6385
6386   if (TREE_CODE (type) == FUNCTION_TYPE
6387       && type_quals != TYPE_UNQUALIFIED)
6388     {
6389       /* This was an error in C++98 (cv-qualifiers cannot be added to
6390          a function type), but DR 295 makes the code well-formed by
6391          dropping the extra qualifiers. */
6392       if (pedantic)
6393         {
6394           tree bad_type = build_qualified_type (type, type_quals);
6395           pedwarn ("ignoring %qV qualifiers added to function type %qT",
6396                    bad_type, type);
6397         }
6398
6399       TREE_TYPE (decl) = TYPE_MAIN_VARIANT (type);
6400       return;
6401     }
6402
6403   /* Avoid setting TREE_READONLY incorrectly.  */
6404   if (/* If the object has a constructor, the constructor may modify
6405          the object.  */
6406       TYPE_NEEDS_CONSTRUCTING (type)
6407       /* If the type isn't complete, we don't know yet if it will need
6408          constructing.  */
6409       || !COMPLETE_TYPE_P (type)
6410       /* If the type has a mutable component, that component might be
6411          modified.  */
6412       || TYPE_HAS_MUTABLE_P (type))
6413     type_quals &= ~TYPE_QUAL_CONST;
6414
6415   c_apply_type_quals_to_decl (type_quals, decl);
6416 }
6417
6418 /* Subroutine of casts_away_constness.  Make T1 and T2 point at
6419    exemplar types such that casting T1 to T2 is casting away constness
6420    if and only if there is no implicit conversion from T1 to T2.  */
6421
6422 static void
6423 casts_away_constness_r (tree *t1, tree *t2)
6424 {
6425   int quals1;
6426   int quals2;
6427
6428   /* [expr.const.cast]
6429
6430      For multi-level pointer to members and multi-level mixed pointers
6431      and pointers to members (conv.qual), the "member" aspect of a
6432      pointer to member level is ignored when determining if a const
6433      cv-qualifier has been cast away.  */
6434   if (TYPE_PTRMEM_P (*t1))
6435     *t1 = build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (*t1));
6436   if (TYPE_PTRMEM_P (*t2))
6437     *t2 = build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (*t2));
6438
6439   /* [expr.const.cast]
6440
6441      For  two  pointer types:
6442
6443             X1 is T1cv1,1 * ... cv1,N *   where T1 is not a pointer type
6444             X2 is T2cv2,1 * ... cv2,M *   where T2 is not a pointer type
6445             K is min(N,M)
6446
6447      casting from X1 to X2 casts away constness if, for a non-pointer
6448      type T there does not exist an implicit conversion (clause
6449      _conv_) from:
6450
6451             Tcv1,(N-K+1) * cv1,(N-K+2) * ... cv1,N *
6452
6453      to
6454
6455             Tcv2,(M-K+1) * cv2,(M-K+2) * ... cv2,M *.  */
6456
6457   if (TREE_CODE (*t1) != POINTER_TYPE
6458       || TREE_CODE (*t2) != POINTER_TYPE)
6459     {
6460       *t1 = cp_build_qualified_type (void_type_node,
6461                                      cp_type_quals (*t1));
6462       *t2 = cp_build_qualified_type (void_type_node,
6463                                      cp_type_quals (*t2));
6464       return;
6465     }
6466
6467   quals1 = cp_type_quals (*t1);
6468   quals2 = cp_type_quals (*t2);
6469   *t1 = TREE_TYPE (*t1);
6470   *t2 = TREE_TYPE (*t2);
6471   casts_away_constness_r (t1, t2);
6472   *t1 = build_pointer_type (*t1);
6473   *t2 = build_pointer_type (*t2);
6474   *t1 = cp_build_qualified_type (*t1, quals1);
6475   *t2 = cp_build_qualified_type (*t2, quals2);
6476 }
6477
6478 /* Returns nonzero if casting from TYPE1 to TYPE2 casts away
6479    constness.  */
6480
6481 static bool
6482 casts_away_constness (tree t1, tree t2)
6483 {
6484   if (TREE_CODE (t2) == REFERENCE_TYPE)
6485     {
6486       /* [expr.const.cast]
6487
6488          Casting from an lvalue of type T1 to an lvalue of type T2
6489          using a reference cast casts away constness if a cast from an
6490          rvalue of type "pointer to T1" to the type "pointer to T2"
6491          casts away constness.  */
6492       t1 = (TREE_CODE (t1) == REFERENCE_TYPE ? TREE_TYPE (t1) : t1);
6493       return casts_away_constness (build_pointer_type (t1),
6494                                    build_pointer_type (TREE_TYPE (t2)));
6495     }
6496
6497   if (TYPE_PTRMEM_P (t1) && TYPE_PTRMEM_P (t2))
6498     /* [expr.const.cast]
6499
6500        Casting from an rvalue of type "pointer to data member of X
6501        of type T1" to the type "pointer to data member of Y of type
6502        T2" casts away constness if a cast from an rvalue of type
6503        "pointer to T1" to the type "pointer to T2" casts away
6504        constness.  */
6505     return casts_away_constness
6506       (build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (t1)),
6507        build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (t2)));
6508
6509   /* Casting away constness is only something that makes sense for
6510      pointer or reference types.  */
6511   if (TREE_CODE (t1) != POINTER_TYPE
6512       || TREE_CODE (t2) != POINTER_TYPE)
6513     return false;
6514
6515   /* Top-level qualifiers don't matter.  */
6516   t1 = TYPE_MAIN_VARIANT (t1);
6517   t2 = TYPE_MAIN_VARIANT (t2);
6518   casts_away_constness_r (&t1, &t2);
6519   if (!can_convert (t2, t1))
6520     return true;
6521
6522   return false;
6523 }
6524
6525 /* If T is a REFERENCE_TYPE return the type to which T refers.
6526    Otherwise, return T itself.  */
6527
6528 tree
6529 non_reference (tree t)
6530 {
6531   if (TREE_CODE (t) == REFERENCE_TYPE)
6532     t = TREE_TYPE (t);
6533   return t;
6534 }
6535
6536
6537 /* Return nonzero if REF is an lvalue valid for this language;
6538    otherwise, print an error message and return zero.  USE says
6539    how the lvalue is being used and so selects the error message.  */
6540
6541 int
6542 lvalue_or_else (tree ref, enum lvalue_use use)
6543 {
6544   int win = lvalue_p (ref);
6545
6546   if (!win)
6547     lvalue_error (use);
6548
6549   return win;
6550 }