gcc/cp/typeck.c

   1 /* Build expressions with type checking for C++ compiler.
   2    Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
   4    Hacked by Michael Tiemann (tiemann@cygnus.com)
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2, or (at your option)
  11 any later version.
  12
  13 GCC is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING.  If not, write to
  20 the Free Software Foundation, 59 Temple Place - Suite 330,
  21 Boston, MA 02111-1307, USA.  */
  22
  23
  24 /* This file is part of the C++ front end.
  25    It contains routines to build C++ expressions given their operands,
  26    including computing the types of the result, C and C++ specific error
  27    checks, and some optimization.  */
  28
  29 #include "config.h"
  30 #include "system.h"
  31 #include "coretypes.h"
  32 #include "tm.h"
  33 #include "tree.h"
  34 #include "rtl.h"
  35 #include "expr.h"
  36 #include "cp-tree.h"
  37 #include "tm_p.h"
  38 #include "flags.h"
  39 #include "output.h"
  40 #include "toplev.h"
  41 #include "diagnostic.h"
  42 #include "target.h"
  43 #include "convert.h"
  44 #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
  61 /* Return the target type of TYPE, which means return T for:
  62    T*, T&, T[], T (...), and otherwise, just T.  */
  63
  64 tree
  65 target_type (tree type)
  66 {
  67   type = non_reference (type);
  68   while (TREE_CODE (type) == POINTER_TYPE
  69          || TREE_CODE (type) == ARRAY_TYPE
  70          || TREE_CODE (type) == FUNCTION_TYPE
  71          || TREE_CODE (type) == METHOD_TYPE
  72          || TYPE_PTRMEM_P (type))
  73     type = TREE_TYPE (type);
  74   return type;
  75 }
  76
  77 /* Do `exp = require_complete_type (exp);' to make sure exp
  78    does not have an incomplete type.  (That includes void types.)
  79    Returns the error_mark_node if the VALUE does not have
  80    complete type when this function returns.  */
  81
  82 tree
  83 require_complete_type (tree value)
  84 {
  85   tree type;
  86
  87   if (processing_template_decl || value == error_mark_node)
  88     return value;
  89
  90   if (TREE_CODE (value) == OVERLOAD)
  91     type = unknown_type_node;
  92   else
  93     type = TREE_TYPE (value);
  94
  95   if (type == error_mark_node)
  96     return error_mark_node;
  97
  98   /* First, detect a valid value with a complete type.  */
  99   if (COMPLETE_TYPE_P (type))
 100     return value;
 101
 102   if (complete_type_or_else (type, value))
 103     return value;
 104   else
 105     return error_mark_node;
 106 }
 107
 108 /* Try to complete TYPE, if it is incomplete.  For example, if TYPE is
 109    a template instantiation, do the instantiation.  Returns TYPE,
 110    whether or not it could be completed, unless something goes
 111    horribly wrong, in which case the error_mark_node is returned.  */
 112
 113 tree
 114 complete_type (tree type)
 115 {
 116   if (type == NULL_TREE)
 117     /* Rather than crash, we return something sure to cause an error
 118        at some point.  */
 119     return error_mark_node;
 120
 121   if (type == error_mark_node || COMPLETE_TYPE_P (type))
 122     ;
 123   else if (TREE_CODE (type) == ARRAY_TYPE && TYPE_DOMAIN (type))
 124     {
 125       tree t = complete_type (TREE_TYPE (type));
 126       if (COMPLETE_TYPE_P (t) && !dependent_type_p (type))
 127         layout_type (type);
 128       TYPE_NEEDS_CONSTRUCTING (type)
 129         = TYPE_NEEDS_CONSTRUCTING (TYPE_MAIN_VARIANT (t));
 130       TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type)
 131         = TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TYPE_MAIN_VARIANT (t));
 132     }
 133   else if (CLASS_TYPE_P (type) && CLASSTYPE_TEMPLATE_INSTANTIATION (type))
 134     instantiate_class_template (TYPE_MAIN_VARIANT (type));
 135
 136   return type;
 137 }
 138
 139 /* Like complete_type, but issue an error if the TYPE cannot be completed.
 140    VALUE is used for informative diagnostics.  DIAG_TYPE indicates the type
 141    of diagnostic: 0 for an error, 1 for a warning, 2 for a pedwarn.
 142    Returns NULL_TREE if the type cannot be made complete.  */
 143
 144 tree
 145 complete_type_or_diagnostic (tree type, tree value, int diag_type)
 146 {
 147   type = complete_type (type);
 148   if (type == error_mark_node)
 149     /* We already issued an error.  */
 150     return NULL_TREE;
 151   else if (!COMPLETE_TYPE_P (type))
 152     {
 153       cxx_incomplete_type_diagnostic (value, type, diag_type);
 154       return NULL_TREE;
 155     }
 156   else
 157     return type;
 158 }
 159
 160 /* Return truthvalue of whether type of EXP is instantiated.  */
 161
 162 int
 163 type_unknown_p (tree exp)
 164 {
 165   return (TREE_CODE (exp) == TREE_LIST
 166           || TREE_TYPE (exp) == unknown_type_node);
 167 }
 168
 169 \f
 170 /* Return the common type of two parameter lists.
 171    We assume that comptypes has already been done and returned 1;
 172    if that isn't so, this may crash.
 173
 174    As an optimization, free the space we allocate if the parameter
 175    lists are already common.  */
 176
 177 tree
 178 commonparms (tree p1, tree p2)
 179 {
 180   tree oldargs = p1, newargs, n;
 181   int i, len;
 182   int any_change = 0;
 183
 184   len = list_length (p1);
 185   newargs = tree_last (p1);
 186
 187   if (newargs == void_list_node)
 188     i = 1;
 189   else
 190     {
 191       i = 0;
 192       newargs = 0;
 193     }
 194
 195   for (; i < len; i++)
 196     newargs = tree_cons (NULL_TREE, NULL_TREE, newargs);
 197
 198   n = newargs;
 199
 200   for (i = 0; p1;
 201        p1 = TREE_CHAIN (p1), p2 = TREE_CHAIN (p2), n = TREE_CHAIN (n), i++)
 202     {
 203       if (TREE_PURPOSE (p1) && !TREE_PURPOSE (p2))
 204         {
 205           TREE_PURPOSE (n) = TREE_PURPOSE (p1);
 206           any_change = 1;
 207         }
 208       else if (! TREE_PURPOSE (p1))
 209         {
 210           if (TREE_PURPOSE (p2))
 211             {
 212               TREE_PURPOSE (n) = TREE_PURPOSE (p2);
 213               any_change = 1;
 214             }
 215         }
 216       else
 217         {
 218           if (1 != simple_cst_equal (TREE_PURPOSE (p1), TREE_PURPOSE (p2)))
 219             any_change = 1;
 220           TREE_PURPOSE (n) = TREE_PURPOSE (p2);
 221         }
 222       if (TREE_VALUE (p1) != TREE_VALUE (p2))
 223         {
 224           any_change = 1;
 225           TREE_VALUE (n) = merge_types (TREE_VALUE (p1), TREE_VALUE (p2));
 226         }
 227       else
 228         TREE_VALUE (n) = TREE_VALUE (p1);
 229     }
 230   if (! any_change)
 231     return oldargs;
 232
 233   return newargs;
 234 }
 235
 236 /* Given a type, perhaps copied for a typedef,
 237    find the "original" version of it.  */
 238 tree
 239 original_type (tree t)
 240 {
 241   while (TYPE_NAME (t) != NULL_TREE)
 242     {
 243       tree x = TYPE_NAME (t);
 244       if (TREE_CODE (x) != TYPE_DECL)
 245         break;
 246       x = DECL_ORIGINAL_TYPE (x);
 247       if (x == NULL_TREE)
 248         break;
 249       t = x;
 250     }
 251   return t;
 252 }
 253
 254 /* T1 and T2 are arithmetic or enumeration types.  Return the type
 255    that will result from the "usual arithmetic conversions" on T1 and
 256    T2 as described in [expr].  */
 257
 258 tree
 259 type_after_usual_arithmetic_conversions (tree t1, tree t2)
 260 {
 261   enum tree_code code1 = TREE_CODE (t1);
 262   enum tree_code code2 = TREE_CODE (t2);
 263   tree attributes;
 264
 265   /* FIXME: Attributes.  */
 266   gcc_assert (ARITHMETIC_TYPE_P (t1)
 267               || TREE_CODE (t1) == COMPLEX_TYPE
 268               || TREE_CODE (t1) == ENUMERAL_TYPE);
 269   gcc_assert (ARITHMETIC_TYPE_P (t2)
 270               || TREE_CODE (t2) == COMPLEX_TYPE
 271               || TREE_CODE (t2) == ENUMERAL_TYPE);
 272
 273   /* In what follows, we slightly generalize the rules given in [expr] so
 274      as to deal with `long long' and `complex'.  First, merge the
 275      attributes.  */
 276   attributes = (*targetm.merge_type_attributes) (t1, t2);
 277
 278   /* If one type is complex, form the common type of the non-complex
 279      components, then make that complex.  Use T1 or T2 if it is the
 280      required type.  */
 281   if (code1 == COMPLEX_TYPE || code2 == COMPLEX_TYPE)
 282     {
 283       tree subtype1 = code1 == COMPLEX_TYPE ? TREE_TYPE (t1) : t1;
 284       tree subtype2 = code2 == COMPLEX_TYPE ? TREE_TYPE (t2) : t2;
 285       tree subtype
 286         = type_after_usual_arithmetic_conversions (subtype1, subtype2);
 287
 288       if (code1 == COMPLEX_TYPE && TREE_TYPE (t1) == subtype)
 289         return build_type_attribute_variant (t1, attributes);
 290       else if (code2 == COMPLEX_TYPE && TREE_TYPE (t2) == subtype)
 291         return build_type_attribute_variant (t2, attributes);
 292       else
 293         return build_type_attribute_variant (build_complex_type (subtype),
 294                                              attributes);
 295     }
 296
 297   /* If only one is real, use it as the result.  */
 298   if (code1 == REAL_TYPE && code2 != REAL_TYPE)
 299     return build_type_attribute_variant (t1, attributes);
 300   if (code2 == REAL_TYPE && code1 != REAL_TYPE)
 301     return build_type_attribute_variant (t2, attributes);
 302
 303   /* Perform the integral promotions.  */
 304   if (code1 != REAL_TYPE)
 305     {
 306       t1 = type_promotes_to (t1);
 307       t2 = type_promotes_to (t2);
 308     }
 309
 310   /* Both real or both integers; use the one with greater precision.  */
 311   if (TYPE_PRECISION (t1) > TYPE_PRECISION (t2))
 312     return build_type_attribute_variant (t1, attributes);
 313   else if (TYPE_PRECISION (t2) > TYPE_PRECISION (t1))
 314     return build_type_attribute_variant (t2, attributes);
 315
 316   /* The types are the same; no need to do anything fancy.  */
 317   if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
 318     return build_type_attribute_variant (t1, attributes);
 319
 320   if (code1 != REAL_TYPE)
 321     {
 322       /* If one is a sizetype, use it so size_binop doesn't blow up.  */
 323       if (TYPE_IS_SIZETYPE (t1) > TYPE_IS_SIZETYPE (t2))
 324         return build_type_attribute_variant (t1, attributes);
 325       if (TYPE_IS_SIZETYPE (t2) > TYPE_IS_SIZETYPE (t1))
 326         return build_type_attribute_variant (t2, attributes);
 327
 328       /* If one is unsigned long long, then convert the other to unsigned
 329          long long.  */
 330       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_long_unsigned_type_node)
 331           || same_type_p (TYPE_MAIN_VARIANT (t2), long_long_unsigned_type_node))
 332         return build_type_attribute_variant (long_long_unsigned_type_node,
 333                                              attributes);
 334       /* If one is a long long, and the other is an unsigned long, and
 335          long long can represent all the values of an unsigned long, then
 336          convert to a long long.  Otherwise, convert to an unsigned long
 337          long.  Otherwise, if either operand is long long, convert the
 338          other to long long.
 339
 340          Since we're here, we know the TYPE_PRECISION is the same;
 341          therefore converting to long long cannot represent all the values
 342          of an unsigned long, so we choose unsigned long long in that
 343          case.  */
 344       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_long_integer_type_node)
 345           || same_type_p (TYPE_MAIN_VARIANT (t2), long_long_integer_type_node))
 346         {
 347           tree t = ((TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 348                     ? long_long_unsigned_type_node
 349                     : long_long_integer_type_node);
 350           return build_type_attribute_variant (t, attributes);
 351         }
 352
 353       /* Go through the same procedure, but for longs.  */
 354       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_unsigned_type_node)
 355           || same_type_p (TYPE_MAIN_VARIANT (t2), long_unsigned_type_node))
 356         return build_type_attribute_variant (long_unsigned_type_node,
 357                                              attributes);
 358       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_integer_type_node)
 359           || same_type_p (TYPE_MAIN_VARIANT (t2), long_integer_type_node))
 360         {
 361           tree t = ((TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 362                     ? long_unsigned_type_node : long_integer_type_node);
 363           return build_type_attribute_variant (t, attributes);
 364         }
 365       /* Otherwise prefer the unsigned one.  */
 366       if (TYPE_UNSIGNED (t1))
 367         return build_type_attribute_variant (t1, attributes);
 368       else
 369         return build_type_attribute_variant (t2, attributes);
 370     }
 371   else
 372     {
 373       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_double_type_node)
 374           || same_type_p (TYPE_MAIN_VARIANT (t2), long_double_type_node))
 375         return build_type_attribute_variant (long_double_type_node,
 376                                              attributes);
 377       if (same_type_p (TYPE_MAIN_VARIANT (t1), double_type_node)
 378           || same_type_p (TYPE_MAIN_VARIANT (t2), double_type_node))
 379         return build_type_attribute_variant (double_type_node,
 380                                              attributes);
 381       if (same_type_p (TYPE_MAIN_VARIANT (t1), float_type_node)
 382           || same_type_p (TYPE_MAIN_VARIANT (t2), float_type_node))
 383         return build_type_attribute_variant (float_type_node,
 384                                              attributes);
 385
 386       /* Two floating-point types whose TYPE_MAIN_VARIANTs are none of
 387          the standard C++ floating-point types.  Logic earlier in this
 388          function has already eliminated the possibility that
 389          TYPE_PRECISION (t2) != TYPE_PRECISION (t1), so there's no
 390          compelling reason to choose one or the other.  */
 391       return build_type_attribute_variant (t1, attributes);
 392     }
 393 }
 394
 395 /* Subroutine of composite_pointer_type to implement the recursive
 396    case.  See that function for documentation fo the parameters.  */
 397
 398 static tree
 399 composite_pointer_type_r (tree t1, tree t2, const char* location)
 400 {
 401   tree pointee1;
 402   tree pointee2;
 403   tree result_type;
 404   tree attributes;
 405
 406   /* Determine the types pointed to by T1 and T2.  */
 407   if (TREE_CODE (t1) == POINTER_TYPE)
 408     {
 409       pointee1 = TREE_TYPE (t1);
 410       pointee2 = TREE_TYPE (t2);
 411     }
 412   else
 413     {
 414       pointee1 = TYPE_PTRMEM_POINTED_TO_TYPE (t1);
 415       pointee2 = TYPE_PTRMEM_POINTED_TO_TYPE (t2);
 416     }
 417
 418   /* [expr.rel]
 419
 420      Otherwise, the composite pointer type is a pointer type
 421      similar (_conv.qual_) to the type of one of the operands,
 422      with a cv-qualification signature (_conv.qual_) that is the
 423      union of the cv-qualification signatures of the operand
 424      types.  */
 425   if (same_type_ignoring_top_level_qualifiers_p (pointee1, pointee2))
 426     result_type = pointee1;
 427   else if ((TREE_CODE (pointee1) == POINTER_TYPE
 428             && TREE_CODE (pointee2) == POINTER_TYPE)
 429            || (TYPE_PTR_TO_MEMBER_P (pointee1)
 430                && TYPE_PTR_TO_MEMBER_P (pointee2)))
 431     result_type = composite_pointer_type_r (pointee1, pointee2, location);
 432   else
 433     {
 434       pedwarn ("%s between distinct pointer types %qT and %qT "
 435                "lacks a cast",
 436                location, t1, t2);
 437       result_type = void_type_node;
 438     }
 439   result_type = cp_build_qualified_type (result_type,
 440                                          (cp_type_quals (pointee1)
 441                                           | cp_type_quals (pointee2)));
 442   /* If the original types were pointers to members, so is the
 443      result.  */
 444   if (TYPE_PTR_TO_MEMBER_P (t1))
 445     {
 446       if (!same_type_p (TYPE_PTRMEM_CLASS_TYPE (t1),
 447                         TYPE_PTRMEM_CLASS_TYPE (t2)))
 448         pedwarn ("%s between distinct pointer types %qT and %qT "
 449                  "lacks a cast",
 450                  location, t1, t2);
 451       result_type = build_ptrmem_type (TYPE_PTRMEM_CLASS_TYPE (t1),
 452                                        result_type);
 453     }
 454   else
 455     result_type = build_pointer_type (result_type);
 456
 457   /* Merge the attributes.  */
 458   attributes = (*targetm.merge_type_attributes) (t1, t2);
 459   return build_type_attribute_variant (result_type, attributes);
 460 }
 461
 462 /* Return the composite pointer type (see [expr.rel]) for T1 and T2.
 463    ARG1 and ARG2 are the values with those types.  The LOCATION is a
 464    string describing the current location, in case an error occurs.
 465
 466    This routine also implements the computation of a common type for
 467    pointers-to-members as per [expr.eq].  */
 468
 469 tree
 470 composite_pointer_type (tree t1, tree t2, tree arg1, tree arg2,
 471                         const char* location)
 472 {
 473   tree class1;
 474   tree class2;
 475
 476   /* [expr.rel]
 477
 478      If one operand is a null pointer constant, the composite pointer
 479      type is the type of the other operand.  */
 480   if (null_ptr_cst_p (arg1))
 481     return t2;
 482   if (null_ptr_cst_p (arg2))
 483     return t1;
 484
 485   /* We have:
 486
 487        [expr.rel]
 488
 489        If one of the operands has type "pointer to cv1 void*", then
 490        the other has type "pointer to cv2T", and the composite pointer
 491        type is "pointer to cv12 void", where cv12 is the union of cv1
 492        and cv2.
 493
 494     If either type is a pointer to void, make sure it is T1.  */
 495   if (TREE_CODE (t2) == POINTER_TYPE && VOID_TYPE_P (TREE_TYPE (t2)))
 496     {
 497       tree t;
 498       t = t1;
 499       t1 = t2;
 500       t2 = t;
 501     }
 502
 503   /* Now, if T1 is a pointer to void, merge the qualifiers.  */
 504   if (TREE_CODE (t1) == POINTER_TYPE && VOID_TYPE_P (TREE_TYPE (t1)))
 505     {
 506       tree attributes;
 507       tree result_type;
 508
 509       if (pedantic && TYPE_PTRFN_P (t2))
 510         pedwarn ("ISO C++ forbids %s between pointer of type %<void *%> "
 511                  "and pointer-to-function", location);
 512       result_type
 513         = cp_build_qualified_type (void_type_node,
 514                                    (cp_type_quals (TREE_TYPE (t1))
 515                                     | cp_type_quals (TREE_TYPE (t2))));
 516       result_type = build_pointer_type (result_type);
 517       /* Merge the attributes.  */
 518       attributes = (*targetm.merge_type_attributes) (t1, t2);
 519       return build_type_attribute_variant (result_type, attributes);
 520     }
 521
 522   /* [expr.eq] permits the application of a pointer conversion to
 523      bring the pointers to a common type.  */
 524   if (TREE_CODE (t1) == POINTER_TYPE && TREE_CODE (t2) == POINTER_TYPE
 525       && CLASS_TYPE_P (TREE_TYPE (t1))
 526       && CLASS_TYPE_P (TREE_TYPE (t2))
 527       && !same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (t1),
 528                                                      TREE_TYPE (t2)))
 529     {
 530       class1 = TREE_TYPE (t1);
 531       class2 = TREE_TYPE (t2);
 532
 533       if (DERIVED_FROM_P (class1, class2))
 534         t2 = (build_pointer_type
 535               (cp_build_qualified_type (class1, TYPE_QUALS (class2))));
 536       else if (DERIVED_FROM_P (class2, class1))
 537         t1 = (build_pointer_type
 538               (cp_build_qualified_type (class2, TYPE_QUALS (class1))));
 539       else
 540         {
 541           error ("%s between distinct pointer types %qT and %qT "
 542                  "lacks a cast", location, t1, t2);
 543           return error_mark_node;
 544         }
 545     }
 546   /* [expr.eq] permits the application of a pointer-to-member
 547      conversion to change the class type of one of the types.  */
 548   else if (TYPE_PTR_TO_MEMBER_P (t1)
 549            && !same_type_p (TYPE_PTRMEM_CLASS_TYPE (t1),
 550                             TYPE_PTRMEM_CLASS_TYPE (t2)))
 551     {
 552       class1 = TYPE_PTRMEM_CLASS_TYPE (t1);
 553       class2 = TYPE_PTRMEM_CLASS_TYPE (t2);
 554
 555       if (DERIVED_FROM_P (class1, class2))
 556         t1 = build_ptrmem_type (class2, TYPE_PTRMEM_POINTED_TO_TYPE (t1));
 557       else if (DERIVED_FROM_P (class2, class1))
 558         t2 = build_ptrmem_type (class1, TYPE_PTRMEM_POINTED_TO_TYPE (t2));
 559       else
 560         {
 561           error ("%s between distinct pointer-to-member types %qT and %qT "
 562                  "lacks a cast", location, t1, t2);
 563           return error_mark_node;
 564         }
 565     }
 566
 567   return composite_pointer_type_r (t1, t2, location);
 568 }
 569
 570 /* Return the merged type of two types.
 571    We assume that comptypes has already been done and returned 1;
 572    if that isn't so, this may crash.
 573
 574    This just combines attributes and default arguments; any other
 575    differences would cause the two types to compare unalike.  */
 576
 577 tree
 578 merge_types (tree t1, tree t2)
 579 {
 580   enum tree_code code1;
 581   enum tree_code code2;
 582   tree attributes;
 583
 584   /* Save time if the two types are the same.  */
 585   if (t1 == t2)
 586     return t1;
 587   if (original_type (t1) == original_type (t2))
 588     return t1;
 589
 590   /* If one type is nonsense, use the other.  */
 591   if (t1 == error_mark_node)
 592     return t2;
 593   if (t2 == error_mark_node)
 594     return t1;
 595
 596   /* Merge the attributes.  */
 597   attributes = (*targetm.merge_type_attributes) (t1, t2);
 598
 599   if (TYPE_PTRMEMFUNC_P (t1))
 600     t1 = TYPE_PTRMEMFUNC_FN_TYPE (t1);
 601   if (TYPE_PTRMEMFUNC_P (t2))
 602     t2 = TYPE_PTRMEMFUNC_FN_TYPE (t2);
 603
 604   code1 = TREE_CODE (t1);
 605   code2 = TREE_CODE (t2);
 606
 607   switch (code1)
 608     {
 609     case POINTER_TYPE:
 610     case REFERENCE_TYPE:
 611       /* For two pointers, do this recursively on the target type.  */
 612       {
 613         tree target = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
 614         int quals = cp_type_quals (t1);
 615
 616         if (code1 == POINTER_TYPE)
 617           t1 = build_pointer_type (target);
 618         else
 619           t1 = build_reference_type (target);
 620         t1 = build_type_attribute_variant (t1, attributes);
 621         t1 = cp_build_qualified_type (t1, quals);
 622
 623         if (TREE_CODE (target) == METHOD_TYPE)
 624           t1 = build_ptrmemfunc_type (t1);
 625
 626         return t1;
 627       }
 628
 629     case OFFSET_TYPE:
 630       {
 631         int quals;
 632         tree pointee;
 633         quals = cp_type_quals (t1);
 634         pointee = merge_types (TYPE_PTRMEM_POINTED_TO_TYPE (t1),
 635                                TYPE_PTRMEM_POINTED_TO_TYPE (t2));
 636         t1 = build_ptrmem_type (TYPE_PTRMEM_CLASS_TYPE (t1),
 637                                 pointee);
 638         t1 = cp_build_qualified_type (t1, quals);
 639         break;
 640       }
 641
 642     case ARRAY_TYPE:
 643       {
 644         tree elt = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
 645         /* Save space: see if the result is identical to one of the args.  */
 646         if (elt == TREE_TYPE (t1) && TYPE_DOMAIN (t1))
 647           return build_type_attribute_variant (t1, attributes);
 648         if (elt == TREE_TYPE (t2) && TYPE_DOMAIN (t2))
 649           return build_type_attribute_variant (t2, attributes);
 650         /* Merge the element types, and have a size if either arg has one.  */
 651         t1 = build_cplus_array_type
 652           (elt, TYPE_DOMAIN (TYPE_DOMAIN (t1) ? t1 : t2));
 653         break;
 654       }
 655
 656     case FUNCTION_TYPE:
 657       /* Function types: prefer the one that specified arg types.
 658          If both do, merge the arg types.  Also merge the return types.  */
 659       {
 660         tree valtype = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
 661         tree p1 = TYPE_ARG_TYPES (t1);
 662         tree p2 = TYPE_ARG_TYPES (t2);
 663         tree rval, raises;
 664
 665         /* Save space: see if the result is identical to one of the args.  */
 666         if (valtype == TREE_TYPE (t1) && ! p2)
 667           return cp_build_type_attribute_variant (t1, attributes);
 668         if (valtype == TREE_TYPE (t2) && ! p1)
 669           return cp_build_type_attribute_variant (t2, attributes);
 670
 671         /* Simple way if one arg fails to specify argument types.  */
 672         if (p1 == NULL_TREE || TREE_VALUE (p1) == void_type_node)
 673           {
 674             rval = build_function_type (valtype, p2);
 675             if ((raises = TYPE_RAISES_EXCEPTIONS (t2)))
 676               rval = build_exception_variant (rval, raises);
 677             return cp_build_type_attribute_variant (rval, attributes);
 678           }
 679         raises = TYPE_RAISES_EXCEPTIONS (t1);
 680         if (p2 == NULL_TREE || TREE_VALUE (p2) == void_type_node)
 681           {
 682             rval = build_function_type (valtype, p1);
 683             if (raises)
 684               rval = build_exception_variant (rval, raises);
 685             return cp_build_type_attribute_variant (rval, attributes);
 686           }
 687
 688         rval = build_function_type (valtype, commonparms (p1, p2));
 689         t1 = build_exception_variant (rval, raises);
 690         break;
 691       }
 692
 693     case METHOD_TYPE:
 694       {
 695         /* Get this value the long way, since TYPE_METHOD_BASETYPE
 696            is just the main variant of this.  */
 697         tree basetype = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (t2)));
 698         tree raises = TYPE_RAISES_EXCEPTIONS (t1);
 699         tree t3;
 700
 701         /* If this was a member function type, get back to the
 702            original type of type member function (i.e., without
 703            the class instance variable up front.  */
 704         t1 = build_function_type (TREE_TYPE (t1),
 705                                   TREE_CHAIN (TYPE_ARG_TYPES (t1)));
 706         t2 = build_function_type (TREE_TYPE (t2),
 707                                   TREE_CHAIN (TYPE_ARG_TYPES (t2)));
 708         t3 = merge_types (t1, t2);
 709         t3 = build_method_type_directly (basetype, TREE_TYPE (t3),
 710                                          TYPE_ARG_TYPES (t3));
 711         t1 = build_exception_variant (t3, raises);
 712         break;
 713       }
 714
 715     case TYPENAME_TYPE:
 716       /* There is no need to merge attributes into a TYPENAME_TYPE.
 717          When the type is instantiated it will have whatever
 718          attributes result from the instantiation.  */
 719       return t1;
 720
 721     default:;
 722     }
 723   return cp_build_type_attribute_variant (t1, attributes);
 724 }
 725
 726 /* Return the common type of two types.
 727    We assume that comptypes has already been done and returned 1;
 728    if that isn't so, this may crash.
 729
 730    This is the type for the result of most arithmetic operations
 731    if the operands have the given two types.  */
 732
 733 tree
 734 common_type (tree t1, tree t2)
 735 {
 736   enum tree_code code1;
 737   enum tree_code code2;
 738
 739   /* If one type is nonsense, bail.  */
 740   if (t1 == error_mark_node || t2 == error_mark_node)
 741     return error_mark_node;
 742
 743   code1 = TREE_CODE (t1);
 744   code2 = TREE_CODE (t2);
 745
 746   if ((ARITHMETIC_TYPE_P (t1) || code1 == ENUMERAL_TYPE
 747        || code1 == COMPLEX_TYPE)
 748       && (ARITHMETIC_TYPE_P (t2) || code2 == ENUMERAL_TYPE
 749           || code2 == COMPLEX_TYPE))
 750     return type_after_usual_arithmetic_conversions (t1, t2);
 751
 752   else if ((TYPE_PTR_P (t1) && TYPE_PTR_P (t2))
 753            || (TYPE_PTRMEM_P (t1) && TYPE_PTRMEM_P (t2))
 754            || (TYPE_PTRMEMFUNC_P (t1) && TYPE_PTRMEMFUNC_P (t2)))
 755     return composite_pointer_type (t1, t2, error_mark_node, error_mark_node,
 756                                    "conversion");
 757   else
 758     gcc_unreachable ();
 759 }
 760 \f
 761 /* Compare two exception specifier types for exactness or subsetness, if
 762    allowed. Returns false for mismatch, true for match (same, or
 763    derived and !exact).
 764
 765    [except.spec] "If a class X ... objects of class X or any class publicly
 766    and unambiguously derived from X. Similarly, if a pointer type Y * ...
 767    exceptions of type Y * or that are pointers to any type publicly and
 768    unambiguously derived from Y. Otherwise a function only allows exceptions
 769    that have the same type ..."
 770    This does not mention cv qualifiers and is different to what throw
 771    [except.throw] and catch [except.catch] will do. They will ignore the
 772    top level cv qualifiers, and allow qualifiers in the pointer to class
 773    example.
 774
 775    We implement the letter of the standard.  */
 776
 777 static bool
 778 comp_except_types (tree a, tree b, bool exact)
 779 {
 780   if (same_type_p (a, b))
 781     return true;
 782   else if (!exact)
 783     {
 784       if (cp_type_quals (a) || cp_type_quals (b))
 785         return false;
 786
 787       if (TREE_CODE (a) == POINTER_TYPE
 788           && TREE_CODE (b) == POINTER_TYPE)
 789         {
 790           a = TREE_TYPE (a);
 791           b = TREE_TYPE (b);
 792           if (cp_type_quals (a) || cp_type_quals (b))
 793             return false;
 794         }
 795
 796       if (TREE_CODE (a) != RECORD_TYPE
 797           || TREE_CODE (b) != RECORD_TYPE)
 798         return false;
 799
 800       if (PUBLICLY_UNIQUELY_DERIVED_P (a, b))
 801         return true;
 802     }
 803   return false;
 804 }
 805
 806 /* Return true if TYPE1 and TYPE2 are equivalent exception specifiers.
 807    If EXACT is false, T2 can be stricter than T1 (according to 15.4/7),
 808    otherwise it must be exact. Exception lists are unordered, but
 809    we've already filtered out duplicates. Most lists will be in order,
 810    we should try to make use of that.  */
 811
 812 bool
 813 comp_except_specs (tree t1, tree t2, bool exact)
 814 {
 815   tree probe;
 816   tree base;
 817   int  length = 0;
 818
 819   if (t1 == t2)
 820     return true;
 821
 822   if (t1 == NULL_TREE)              /* T1 is ...  */
 823     return t2 == NULL_TREE || !exact;
 824   if (!TREE_VALUE (t1)) /* t1 is EMPTY */
 825     return t2 != NULL_TREE && !TREE_VALUE (t2);
 826   if (t2 == NULL_TREE)              /* T2 is ...  */
 827     return false;
 828   if (TREE_VALUE (t1) && !TREE_VALUE (t2)) /* T2 is EMPTY, T1 is not */
 829     return !exact;
 830
 831   /* Neither set is ... or EMPTY, make sure each part of T2 is in T1.
 832      Count how many we find, to determine exactness. For exact matching and
 833      ordered T1, T2, this is an O(n) operation, otherwise its worst case is
 834      O(nm).  */
 835   for (base = t1; t2 != NULL_TREE; t2 = TREE_CHAIN (t2))
 836     {
 837       for (probe = base; probe != NULL_TREE; probe = TREE_CHAIN (probe))
 838         {
 839           tree a = TREE_VALUE (probe);
 840           tree b = TREE_VALUE (t2);
 841
 842           if (comp_except_types (a, b, exact))
 843             {
 844               if (probe == base && exact)
 845                 base = TREE_CHAIN (probe);
 846               length++;
 847               break;
 848             }
 849         }
 850       if (probe == NULL_TREE)
 851         return false;
 852     }
 853   return !exact || base == NULL_TREE || length == list_length (t1);
 854 }
 855
 856 /* Compare the array types T1 and T2.  ALLOW_REDECLARATION is true if
 857    [] can match [size].  */
 858
 859 static bool
 860 comp_array_types (tree t1, tree t2, bool allow_redeclaration)
 861 {
 862   tree d1;
 863   tree d2;
 864   tree max1, max2;
 865
 866   if (t1 == t2)
 867     return true;
 868
 869   /* The type of the array elements must be the same.  */
 870   if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
 871     return false;
 872
 873   d1 = TYPE_DOMAIN (t1);
 874   d2 = TYPE_DOMAIN (t2);
 875
 876   if (d1 == d2)
 877     return true;
 878
 879   /* If one of the arrays is dimensionless, and the other has a
 880      dimension, they are of different types.  However, it is valid to
 881      write:
 882
 883        extern int a[];
 884        int a[3];
 885
 886      by [basic.link]:
 887
 888        declarations for an array object can specify
 889        array types that differ by the presence or absence of a major
 890        array bound (_dcl.array_).  */
 891   if (!d1 || !d2)
 892     return allow_redeclaration;
 893
 894   /* Check that the dimensions are the same.  */
 895
 896   if (!cp_tree_equal (TYPE_MIN_VALUE (d1), TYPE_MIN_VALUE (d2)))
 897     return false;
 898   max1 = TYPE_MAX_VALUE (d1);
 899   max2 = TYPE_MAX_VALUE (d2);
 900   if (processing_template_decl && !abi_version_at_least (2)
 901       && !value_dependent_expression_p (max1)
 902       && !value_dependent_expression_p (max2))
 903     {
 904       /* With abi-1 we do not fold non-dependent array bounds, (and
 905          consequently mangle them incorrectly).  We must therefore
 906          fold them here, to verify the domains have the same
 907          value.  */
 908       max1 = fold (max1);
 909       max2 = fold (max2);
 910     }
 911
 912   if (!cp_tree_equal (max1, max2))
 913     return false;
 914
 915   return true;
 916 }
 917
 918 /* Return true if T1 and T2 are related as allowed by STRICT.  STRICT
 919    is a bitwise-or of the COMPARE_* flags.  */
 920
 921 bool
 922 comptypes (tree t1, tree t2, int strict)
 923 {
 924   int retval;
 925
 926   if (t1 == t2)
 927     return true;
 928
 929   /* Suppress errors caused by previously reported errors.  */
 930   if (t1 == error_mark_node || t2 == error_mark_node)
 931     return false;
 932
 933   gcc_assert (TYPE_P (t1) && TYPE_P (t2));
 934
 935   /* TYPENAME_TYPEs should be resolved if the qualifying scope is the
 936      current instantiation.  */
 937   if (TREE_CODE (t1) == TYPENAME_TYPE)
 938     {
 939       tree resolved = resolve_typename_type (t1, /*only_current_p=*/true);
 940
 941       if (resolved != error_mark_node)
 942         t1 = resolved;
 943     }
 944
 945   if (TREE_CODE (t2) == TYPENAME_TYPE)
 946     {
 947       tree resolved = resolve_typename_type (t2, /*only_current_p=*/true);
 948
 949       if (resolved != error_mark_node)
 950         t2 = resolved;
 951     }
 952
 953   /* If either type is the internal version of sizetype, use the
 954      language version.  */
 955   if (TREE_CODE (t1) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t1)
 956       && TYPE_ORIG_SIZE_TYPE (t1))
 957     t1 = TYPE_ORIG_SIZE_TYPE (t1);
 958
 959   if (TREE_CODE (t2) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t2)
 960       && TYPE_ORIG_SIZE_TYPE (t2))
 961     t2 = TYPE_ORIG_SIZE_TYPE (t2);
 962
 963   if (TYPE_PTRMEMFUNC_P (t1))
 964     t1 = TYPE_PTRMEMFUNC_FN_TYPE (t1);
 965   if (TYPE_PTRMEMFUNC_P (t2))
 966     t2 = TYPE_PTRMEMFUNC_FN_TYPE (t2);
 967
 968   /* Different classes of types can't be compatible.  */
 969   if (TREE_CODE (t1) != TREE_CODE (t2))
 970     return false;
 971
 972   /* Qualifiers must match.  For array types, we will check when we
 973      recur on the array element types.  */
 974   if (TREE_CODE (t1) != ARRAY_TYPE
 975       && TYPE_QUALS (t1) != TYPE_QUALS (t2))
 976     return false;
 977   if (TYPE_FOR_JAVA (t1) != TYPE_FOR_JAVA (t2))
 978     return false;
 979
 980   /* Allow for two different type nodes which have essentially the same
 981      definition.  Note that we already checked for equality of the type
 982      qualifiers (just above).  */
 983
 984   if (TREE_CODE (t1) != ARRAY_TYPE
 985       && TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
 986     return true;
 987
 988   if (!(*targetm.comp_type_attributes) (t1, t2))
 989     return false;
 990
 991   switch (TREE_CODE (t1))
 992     {
 993     case TEMPLATE_TEMPLATE_PARM:
 994     case BOUND_TEMPLATE_TEMPLATE_PARM:
 995       if (TEMPLATE_TYPE_IDX (t1) != TEMPLATE_TYPE_IDX (t2)
 996           || TEMPLATE_TYPE_LEVEL (t1) != TEMPLATE_TYPE_LEVEL (t2))
 997         return false;
 998       if (!comp_template_parms
 999           (DECL_TEMPLATE_PARMS (TEMPLATE_TEMPLATE_PARM_TEMPLATE_DECL (t1)),
1000            DECL_TEMPLATE_PARMS (TEMPLATE_TEMPLATE_PARM_TEMPLATE_DECL (t2))))
1001         return false;
1002       if (TREE_CODE (t1) == TEMPLATE_TEMPLATE_PARM)
1003         return true;
1004       /* Don't check inheritance.  */
1005       strict = COMPARE_STRICT;
1006       /* Fall through.  */
1007
1008     case RECORD_TYPE:
1009     case UNION_TYPE:
1010       if (TYPE_TEMPLATE_INFO (t1) && TYPE_TEMPLATE_INFO (t2)
1011           && (TYPE_TI_TEMPLATE (t1) == TYPE_TI_TEMPLATE (t2)
1012               || TREE_CODE (t1) == BOUND_TEMPLATE_TEMPLATE_PARM)
1013           && comp_template_args (TYPE_TI_ARGS (t1), TYPE_TI_ARGS (t2)))
1014         return true;
1015
1016       if ((strict & COMPARE_BASE) && DERIVED_FROM_P (t1, t2))
1017         return true;
1018       else if ((strict & COMPARE_DERIVED) && DERIVED_FROM_P (t2, t1))
1019         return true;
1020
1021       /* We may be dealing with Objective-C instances...  */
1022       if (TREE_CODE (t1) == RECORD_TYPE
1023           && ((retval = objc_comptypes (t1, t2, 0)) >= 0))
1024          return retval;
1025       /* ...but fall through if we are not.  */
1026
1027       return false;
1028
1029     case OFFSET_TYPE:
1030       if (!comptypes (TYPE_OFFSET_BASETYPE (t1), TYPE_OFFSET_BASETYPE (t2),
1031                       strict & ~COMPARE_REDECLARATION))
1032         return false;
1033       return same_type_p (TREE_TYPE (t1), TREE_TYPE (t2));
1034
1035     case POINTER_TYPE:
1036     case REFERENCE_TYPE:
1037       return TYPE_MODE (t1) == TYPE_MODE (t2)
1038              && TYPE_REF_CAN_ALIAS_ALL (t1) == TYPE_REF_CAN_ALIAS_ALL (t2)
1039              && same_type_p (TREE_TYPE (t1), TREE_TYPE (t2));
1040
1041     case METHOD_TYPE:
1042     case FUNCTION_TYPE:
1043       if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
1044         return false;
1045       return compparms (TYPE_ARG_TYPES (t1), TYPE_ARG_TYPES (t2));
1046
1047     case ARRAY_TYPE:
1048       /* Target types must match incl. qualifiers.  */
1049       return comp_array_types (t1, t2, !!(strict & COMPARE_REDECLARATION));
1050
1051     case TEMPLATE_TYPE_PARM:
1052       return (TEMPLATE_TYPE_IDX (t1) == TEMPLATE_TYPE_IDX (t2)
1053               && TEMPLATE_TYPE_LEVEL (t1) == TEMPLATE_TYPE_LEVEL (t2));
1054
1055     case TYPENAME_TYPE:
1056       if (!cp_tree_equal (TYPENAME_TYPE_FULLNAME (t1),
1057                           TYPENAME_TYPE_FULLNAME (t2)))
1058         return false;
1059       return same_type_p (TYPE_CONTEXT (t1), TYPE_CONTEXT (t2));
1060
1061     case UNBOUND_CLASS_TEMPLATE:
1062       if (!cp_tree_equal (TYPE_IDENTIFIER (t1), TYPE_IDENTIFIER (t2)))
1063         return false;
1064       return same_type_p (TYPE_CONTEXT (t1), TYPE_CONTEXT (t2));
1065
1066     case COMPLEX_TYPE:
1067       return same_type_p (TREE_TYPE (t1), TREE_TYPE (t2));
1068
1069     case VECTOR_TYPE:
1070       return TYPE_VECTOR_SUBPARTS (t1) == TYPE_VECTOR_SUBPARTS (t2)
1071              && same_type_p (TREE_TYPE (t1), TREE_TYPE (t2));
1072       break;
1073
1074     default:
1075       break;
1076     }
1077   return false;
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   if (TREE_CODE (member) == PSEUDO_DTOR_EXPR)
1581     return member;
1582
1583   gcc_assert (DECL_P (member) || BASELINK_P (member));
1584
1585   /* [expr.ref]
1586
1587      The type of the first expression shall be "class object" (of a
1588      complete type).  */
1589   object_type = TREE_TYPE (object);
1590   if (!currently_open_class (object_type)
1591       && !complete_type_or_else (object_type, object))
1592     return error_mark_node;
1593   if (!CLASS_TYPE_P (object_type))
1594     {
1595       error ("request for member %qD in %qE, which is of non-class type %qT",
1596              member, object, object_type);
1597       return error_mark_node;
1598     }
1599
1600   /* The standard does not seem to actually say that MEMBER must be a
1601      member of OBJECT_TYPE.  However, that is clearly what is
1602      intended.  */
1603   if (DECL_P (member))
1604     {
1605       member_scope = DECL_CLASS_CONTEXT (member);
1606       mark_used (member);
1607       if (TREE_DEPRECATED (member))
1608         warn_deprecated_use (member);
1609     }
1610   else
1611     member_scope = BINFO_TYPE (BASELINK_BINFO (member));
1612   /* If MEMBER is from an anonymous aggregate, MEMBER_SCOPE will
1613      presently be the anonymous union.  Go outwards until we find a
1614      type related to OBJECT_TYPE.  */
1615   while (ANON_AGGR_TYPE_P (member_scope)
1616          && !same_type_ignoring_top_level_qualifiers_p (member_scope,
1617                                                         object_type))
1618     member_scope = TYPE_CONTEXT (member_scope);
1619   if (!member_scope || !DERIVED_FROM_P (member_scope, object_type))
1620     {
1621       if (TREE_CODE (member) == FIELD_DECL)
1622         error ("invalid use of nonstatic data member %qE", member);
1623       else
1624         error ("%qD is not a member of %qT", member, object_type);
1625       return error_mark_node;
1626     }
1627
1628   /* Transform `(a, b).x' into `(*(a, &b)).x', `(a ? b : c).x' into
1629      `(*(a ?  &b : &c)).x', and so on.  A COND_EXPR is only an lvalue
1630      in the frontend; only _DECLs and _REFs are lvalues in the backend.  */
1631   {
1632     tree temp = unary_complex_lvalue (ADDR_EXPR, object);
1633     if (temp)
1634       object = build_indirect_ref (temp, NULL);
1635   }
1636
1637   /* In [expr.ref], there is an explicit list of the valid choices for
1638      MEMBER.  We check for each of those cases here.  */
1639   if (TREE_CODE (member) == VAR_DECL)
1640     {
1641       /* A static data member.  */
1642       result = member;
1643       /* If OBJECT has side-effects, they are supposed to occur.  */
1644       if (TREE_SIDE_EFFECTS (object))
1645         result = build2 (COMPOUND_EXPR, TREE_TYPE (result), object, result);
1646     }
1647   else if (TREE_CODE (member) == FIELD_DECL)
1648     {
1649       /* A non-static data member.  */
1650       bool null_object_p;
1651       int type_quals;
1652       tree member_type;
1653
1654       null_object_p = (TREE_CODE (object) == INDIRECT_REF
1655                        && integer_zerop (TREE_OPERAND (object, 0)));
1656
1657       /* Convert OBJECT to the type of MEMBER.  */
1658       if (!same_type_p (TYPE_MAIN_VARIANT (object_type),
1659                         TYPE_MAIN_VARIANT (member_scope)))
1660         {
1661           tree binfo;
1662           base_kind kind;
1663
1664           binfo = lookup_base (access_path ? access_path : object_type,
1665                                member_scope, ba_unique,  &kind);
1666           if (binfo == error_mark_node)
1667             return error_mark_node;
1668
1669           /* It is invalid to try to get to a virtual base of a
1670              NULL object.  The most common cause is invalid use of
1671              offsetof macro.  */
1672           if (null_object_p && kind == bk_via_virtual)
1673             {
1674               error ("invalid access to non-static data member %qD of "
1675                      "NULL object",
1676                      member);
1677               error ("(perhaps the %<offsetof%> macro was used incorrectly)");
1678               return error_mark_node;
1679             }
1680
1681           /* Convert to the base.  */
1682           object = build_base_path (PLUS_EXPR, object, binfo,
1683                                     /*nonnull=*/1);
1684           /* If we found the base successfully then we should be able
1685              to convert to it successfully.  */
1686           gcc_assert (object != error_mark_node);
1687         }
1688
1689       /* Complain about other invalid uses of offsetof, even though they will
1690          give the right answer.  Note that we complain whether or not they
1691          actually used the offsetof macro, since there's no way to know at this
1692          point.  So we just give a warning, instead of a pedwarn.  */
1693       /* Do not produce this warning for base class field references, because
1694          we know for a fact that didn't come from offsetof.  This does occur
1695          in various testsuite cases where a null object is passed where a
1696          vtable access is required.  */
1697       if (null_object_p && warn_invalid_offsetof
1698           && CLASSTYPE_NON_POD_P (object_type)
1699           && !DECL_FIELD_IS_BASE (member)
1700           && !skip_evaluation)
1701         {
1702           warning ("invalid access to non-static data member %qD of NULL object",
1703                    member);
1704           warning  ("(perhaps the %<offsetof%> macro was used incorrectly)");
1705         }
1706
1707       /* If MEMBER is from an anonymous aggregate, we have converted
1708          OBJECT so that it refers to the class containing the
1709          anonymous union.  Generate a reference to the anonymous union
1710          itself, and recur to find MEMBER.  */
1711       if (ANON_AGGR_TYPE_P (DECL_CONTEXT (member))
1712           /* When this code is called from build_field_call, the
1713              object already has the type of the anonymous union.
1714              That is because the COMPONENT_REF was already
1715              constructed, and was then disassembled before calling
1716              build_field_call.  After the function-call code is
1717              cleaned up, this waste can be eliminated.  */
1718           && (!same_type_ignoring_top_level_qualifiers_p
1719               (TREE_TYPE (object), DECL_CONTEXT (member))))
1720         {
1721           tree anonymous_union;
1722
1723           anonymous_union = lookup_anon_field (TREE_TYPE (object),
1724                                                DECL_CONTEXT (member));
1725           object = build_class_member_access_expr (object,
1726                                                    anonymous_union,
1727                                                    /*access_path=*/NULL_TREE,
1728                                                    preserve_reference);
1729         }
1730
1731       /* Compute the type of the field, as described in [expr.ref].  */
1732       type_quals = TYPE_UNQUALIFIED;
1733       member_type = TREE_TYPE (member);
1734       if (TREE_CODE (member_type) != REFERENCE_TYPE)
1735         {
1736           type_quals = (cp_type_quals (member_type)
1737                         | cp_type_quals (object_type));
1738
1739           /* A field is const (volatile) if the enclosing object, or the
1740              field itself, is const (volatile).  But, a mutable field is
1741              not const, even within a const object.  */
1742           if (DECL_MUTABLE_P (member))
1743             type_quals &= ~TYPE_QUAL_CONST;
1744           member_type = cp_build_qualified_type (member_type, type_quals);
1745         }
1746
1747       result = build3 (COMPONENT_REF, member_type, object, member,
1748                        NULL_TREE);
1749       result = fold_if_not_in_template (result);
1750
1751       /* Mark the expression const or volatile, as appropriate.  Even
1752          though we've dealt with the type above, we still have to mark the
1753          expression itself.  */
1754       if (type_quals & TYPE_QUAL_CONST)
1755         TREE_READONLY (result) = 1;
1756       else if (type_quals & TYPE_QUAL_VOLATILE)
1757         TREE_THIS_VOLATILE (result) = 1;
1758     }
1759   else if (BASELINK_P (member))
1760     {
1761       /* The member is a (possibly overloaded) member function.  */
1762       tree functions;
1763       tree type;
1764
1765       /* If the MEMBER is exactly one static member function, then we
1766          know the type of the expression.  Otherwise, we must wait
1767          until overload resolution has been performed.  */
1768       functions = BASELINK_FUNCTIONS (member);
1769       if (TREE_CODE (functions) == FUNCTION_DECL
1770           && DECL_STATIC_FUNCTION_P (functions))
1771         type = TREE_TYPE (functions);
1772       else
1773         type = unknown_type_node;
1774       /* Note that we do not convert OBJECT to the BASELINK_BINFO
1775          base.  That will happen when the function is called.  */
1776       result = build3 (COMPONENT_REF, type, object, member, NULL_TREE);
1777     }
1778   else if (TREE_CODE (member) == CONST_DECL)
1779     {
1780       /* The member is an enumerator.  */
1781       result = member;
1782       /* If OBJECT has side-effects, they are supposed to occur.  */
1783       if (TREE_SIDE_EFFECTS (object))
1784         result = build2 (COMPOUND_EXPR, TREE_TYPE (result),
1785                          object, result);
1786     }
1787   else
1788     {
1789       error ("invalid use of %qD", member);
1790       return error_mark_node;
1791     }
1792
1793   if (!preserve_reference)
1794     /* [expr.ref]
1795
1796        If E2 is declared to have type "reference to T", then ... the
1797        type of E1.E2 is T.  */
1798     result = convert_from_reference (result);
1799
1800   return result;
1801 }
1802
1803 /* Return the destructor denoted by OBJECT.SCOPE::~DTOR_NAME, or, if
1804    SCOPE is NULL, by OBJECT.~DTOR_NAME.  */
1805
1806 static tree
1807 lookup_destructor (tree object, tree scope, tree dtor_name)
1808 {
1809   tree object_type = TREE_TYPE (object);
1810   tree dtor_type = TREE_OPERAND (dtor_name, 0);
1811   tree expr;
1812
1813   if (scope && !check_dtor_name (scope, dtor_name))
1814     {
1815       error ("qualified type %qT does not match destructor name ~%qT",
1816              scope, dtor_type);
1817       return error_mark_node;
1818     }
1819   if (!DERIVED_FROM_P (dtor_type, TYPE_MAIN_VARIANT (object_type)))
1820     {
1821       error ("the type being destroyed is %qT, but the destructor refers to %qT",
1822              TYPE_MAIN_VARIANT (object_type), dtor_type);
1823       return error_mark_node;
1824     }
1825   if (!TYPE_HAS_DESTRUCTOR (dtor_type))
1826     return build3 (PSEUDO_DTOR_EXPR, void_type_node, object, scope,
1827                    dtor_type);
1828   expr = lookup_member (dtor_type, complete_dtor_identifier,
1829                         /*protect=*/1, /*want_type=*/false);
1830   expr = (adjust_result_of_qualified_name_lookup
1831           (expr, dtor_type, object_type));
1832   return expr;
1833 }
1834
1835 /* This function is called by the parser to process a class member
1836    access expression of the form OBJECT.NAME.  NAME is a node used by
1837    the parser to represent a name; it is not yet a DECL.  It may,
1838    however, be a BASELINK where the BASELINK_FUNCTIONS is a
1839    TEMPLATE_ID_EXPR.  Templates must be looked up by the parser, and
1840    there is no reason to do the lookup twice, so the parser keeps the
1841    BASELINK.  */
1842
1843 tree
1844 finish_class_member_access_expr (tree object, tree name)
1845 {
1846   tree expr;
1847   tree object_type;
1848   tree member;
1849   tree access_path = NULL_TREE;
1850   tree orig_object = object;
1851   tree orig_name = name;
1852
1853   if (object == error_mark_node || name == error_mark_node)
1854     return error_mark_node;
1855
1856   object_type = TREE_TYPE (object);
1857
1858   if (processing_template_decl)
1859     {
1860       if (/* If OBJECT_TYPE is dependent, so is OBJECT.NAME.  */
1861           dependent_type_p (object_type)
1862           /* If NAME is just an IDENTIFIER_NODE, then the expression
1863              is dependent.  */
1864           || TREE_CODE (object) == IDENTIFIER_NODE
1865           /* If NAME is "f<args>", where either 'f' or 'args' is
1866              dependent, then the expression is dependent.  */
1867           || (TREE_CODE (name) == TEMPLATE_ID_EXPR
1868               && dependent_template_id_p (TREE_OPERAND (name, 0),
1869                                           TREE_OPERAND (name, 1)))
1870           /* If NAME is "T::X" where "T" is dependent, then the
1871              expression is dependent.  */
1872           || (TREE_CODE (name) == SCOPE_REF
1873               && TYPE_P (TREE_OPERAND (name, 0))
1874               && dependent_type_p (TREE_OPERAND (name, 0))))
1875         return build_min_nt (COMPONENT_REF, object, name, NULL_TREE);
1876       object = build_non_dependent_expr (object);
1877     }
1878
1879   /* [expr.ref]
1880
1881      The type of the first expression shall be "class object" (of a
1882      complete type).  */
1883   if (!currently_open_class (object_type)
1884       && !complete_type_or_else (object_type, object))
1885     return error_mark_node;
1886   if (!CLASS_TYPE_P (object_type))
1887     {
1888       error ("request for member %qD in %qE, which is of non-class type %qT",
1889              name, object, object_type);
1890       return error_mark_node;
1891     }
1892
1893   if (BASELINK_P (name))
1894     {
1895       /* A member function that has already been looked up.  */
1896       gcc_assert (TREE_CODE (BASELINK_FUNCTIONS (name)) == TEMPLATE_ID_EXPR);
1897       member = name;
1898     }
1899   else
1900     {
1901       bool is_template_id = false;
1902       tree template_args = NULL_TREE;
1903       tree scope;
1904
1905       if (TREE_CODE (name) == TEMPLATE_ID_EXPR)
1906         {
1907           is_template_id = true;
1908           template_args = TREE_OPERAND (name, 1);
1909           name = TREE_OPERAND (name, 0);
1910
1911           if (TREE_CODE (name) == OVERLOAD)
1912             name = DECL_NAME (get_first_fn (name));
1913           else if (DECL_P (name))
1914             name = DECL_NAME (name);
1915         }
1916
1917       if (TREE_CODE (name) == SCOPE_REF)
1918         {
1919           /* A qualified name.  The qualifying class or namespace `S' has
1920              already been looked up; it is either a TYPE or a
1921              NAMESPACE_DECL.  The member name is either an IDENTIFIER_NODE
1922              or a BIT_NOT_EXPR.  */
1923           scope = TREE_OPERAND (name, 0);
1924           name = TREE_OPERAND (name, 1);
1925           gcc_assert (CLASS_TYPE_P (scope)
1926                       || TREE_CODE (scope) == NAMESPACE_DECL);
1927           gcc_assert (TREE_CODE (name) == IDENTIFIER_NODE
1928                       || TREE_CODE (name) == BIT_NOT_EXPR);
1929
1930           /* If SCOPE is a namespace, then the qualified name does not
1931              name a member of OBJECT_TYPE.  */
1932           if (TREE_CODE (scope) == NAMESPACE_DECL)
1933             {
1934               error ("%<%D::%D%> is not a member of %qT",
1935                      scope, name, object_type);
1936               return error_mark_node;
1937             }
1938
1939           /* Find the base of OBJECT_TYPE corresponding to SCOPE.  */
1940           access_path = lookup_base (object_type, scope, ba_check, NULL);
1941           if (access_path == error_mark_node)
1942             return error_mark_node;
1943           if (!access_path)
1944             {
1945               error ("%qT is not a base of %qT", scope, object_type);
1946               return error_mark_node;
1947             }
1948         }
1949       else
1950         {
1951           scope = NULL_TREE;
1952           access_path = object_type;
1953         }
1954
1955       if (TREE_CODE (name) == BIT_NOT_EXPR)
1956         member = lookup_destructor (object, scope, name);
1957       else
1958         {
1959           /* Look up the member.  */
1960           member = lookup_member (access_path, name, /*protect=*/1,
1961                                   /*want_type=*/false);
1962           if (member == NULL_TREE)
1963             {
1964               error ("%qD has no member named %qE", object_type, name);
1965               return error_mark_node;
1966             }
1967           if (member == error_mark_node)
1968             return error_mark_node;
1969         }
1970
1971       if (is_template_id)
1972         {
1973           tree template = member;
1974
1975           if (BASELINK_P (template))
1976             template = lookup_template_function (template, template_args);
1977           else
1978             {
1979               error ("%qD is not a member template function", name);
1980               return error_mark_node;
1981             }
1982         }
1983     }
1984
1985   if (TREE_DEPRECATED (member))
1986     warn_deprecated_use (member);
1987
1988   expr = build_class_member_access_expr (object, member, access_path,
1989                                          /*preserve_reference=*/false);
1990   if (processing_template_decl && expr != error_mark_node)
1991     return build_min_non_dep (COMPONENT_REF, expr,
1992                               orig_object, orig_name, NULL_TREE);
1993   return expr;
1994 }
1995
1996 /* Return an expression for the MEMBER_NAME field in the internal
1997    representation of PTRMEM, a pointer-to-member function.  (Each
1998    pointer-to-member function type gets its own RECORD_TYPE so it is
1999    more convenient to access the fields by name than by FIELD_DECL.)
2000    This routine converts the NAME to a FIELD_DECL and then creates the
2001    node for the complete expression.  */
2002
2003 tree
2004 build_ptrmemfunc_access_expr (tree ptrmem, tree member_name)
2005 {
2006   tree ptrmem_type;
2007   tree member;
2008   tree member_type;
2009
2010   /* This code is a stripped down version of
2011      build_class_member_access_expr.  It does not work to use that
2012      routine directly because it expects the object to be of class
2013      type.  */
2014   ptrmem_type = TREE_TYPE (ptrmem);
2015   gcc_assert (TYPE_PTRMEMFUNC_P (ptrmem_type));
2016   member = lookup_member (ptrmem_type, member_name, /*protect=*/0,
2017                           /*want_type=*/false);
2018   member_type = cp_build_qualified_type (TREE_TYPE (member),
2019                                          cp_type_quals (ptrmem_type));
2020   return fold (build3 (COMPONENT_REF, member_type,
2021                        ptrmem, member, NULL_TREE));
2022 }
2023
2024 /* Given an expression PTR for a pointer, return an expression
2025    for the value pointed to.
2026    ERRORSTRING is the name of the operator to appear in error messages.
2027
2028    This function may need to overload OPERATOR_FNNAME.
2029    Must also handle REFERENCE_TYPEs for C++.  */
2030
2031 tree
2032 build_x_indirect_ref (tree expr, const char *errorstring)
2033 {
2034   tree orig_expr = expr;
2035   tree rval;
2036
2037   if (processing_template_decl)
2038     {
2039       if (type_dependent_expression_p (expr))
2040         return build_min_nt (INDIRECT_REF, expr);
2041       expr = build_non_dependent_expr (expr);
2042     }
2043
2044   rval = build_new_op (INDIRECT_REF, LOOKUP_NORMAL, expr, NULL_TREE,
2045                        NULL_TREE, /*overloaded_p=*/NULL);
2046   if (!rval)
2047     rval = build_indirect_ref (expr, errorstring);
2048
2049   if (processing_template_decl && rval != error_mark_node)
2050     return build_min_non_dep (INDIRECT_REF, rval, orig_expr);
2051   else
2052     return rval;
2053 }
2054
2055 tree
2056 build_indirect_ref (tree ptr, const char *errorstring)
2057 {
2058   tree pointer, type;
2059
2060   if (ptr == error_mark_node)
2061     return error_mark_node;
2062
2063   if (ptr == current_class_ptr)
2064     return current_class_ref;
2065
2066   pointer = (TREE_CODE (TREE_TYPE (ptr)) == REFERENCE_TYPE
2067              ? ptr : decay_conversion (ptr));
2068   type = TREE_TYPE (pointer);
2069
2070   if (POINTER_TYPE_P (type))
2071     {
2072       /* [expr.unary.op]
2073
2074          If the type of the expression is "pointer to T," the type
2075          of  the  result  is  "T."
2076
2077          We must use the canonical variant because certain parts of
2078          the back end, like fold, do pointer comparisons between
2079          types.  */
2080       tree t = canonical_type_variant (TREE_TYPE (type));
2081
2082       if (VOID_TYPE_P (t))
2083         {
2084           /* A pointer to incomplete type (other than cv void) can be
2085              dereferenced [expr.unary.op]/1  */
2086           error ("%qT is not a pointer-to-object type", type);
2087           return error_mark_node;
2088         }
2089       else if (TREE_CODE (pointer) == ADDR_EXPR
2090                && same_type_p (t, TREE_TYPE (TREE_OPERAND (pointer, 0))))
2091         /* The POINTER was something like `&x'.  We simplify `*&x' to
2092            `x'.  */
2093         return TREE_OPERAND (pointer, 0);
2094       else
2095         {
2096           tree ref = build1 (INDIRECT_REF, t, pointer);
2097
2098           /* We *must* set TREE_READONLY when dereferencing a pointer to const,
2099              so that we get the proper error message if the result is used
2100              to assign to.  Also, &* is supposed to be a no-op.  */
2101           TREE_READONLY (ref) = CP_TYPE_CONST_P (t);
2102           TREE_THIS_VOLATILE (ref) = CP_TYPE_VOLATILE_P (t);
2103           TREE_SIDE_EFFECTS (ref)
2104             = (TREE_THIS_VOLATILE (ref) || TREE_SIDE_EFFECTS (pointer));
2105           return ref;
2106         }
2107     }
2108   /* `pointer' won't be an error_mark_node if we were given a
2109      pointer to member, so it's cool to check for this here.  */
2110   else if (TYPE_PTR_TO_MEMBER_P (type))
2111     error ("invalid use of %qs on pointer to member", errorstring);
2112   else if (pointer != error_mark_node)
2113     {
2114       if (errorstring)
2115         error ("invalid type argument of %qs", errorstring);
2116       else
2117         error ("invalid type argument");
2118     }
2119   return error_mark_node;
2120 }
2121
2122 /* This handles expressions of the form "a[i]", which denotes
2123    an array reference.
2124
2125    This is logically equivalent in C to *(a+i), but we may do it differently.
2126    If A is a variable or a member, we generate a primitive ARRAY_REF.
2127    This avoids forcing the array out of registers, and can work on
2128    arrays that are not lvalues (for example, members of structures returned
2129    by functions).
2130
2131    If INDEX is of some user-defined type, it must be converted to
2132    integer type.  Otherwise, to make a compatible PLUS_EXPR, it
2133    will inherit the type of the array, which will be some pointer type.  */
2134
2135 tree
2136 build_array_ref (tree array, tree idx)
2137 {
2138   if (idx == 0)
2139     {
2140       error ("subscript missing in array reference");
2141       return error_mark_node;
2142     }
2143
2144   if (TREE_TYPE (array) == error_mark_node
2145       || TREE_TYPE (idx) == error_mark_node)
2146     return error_mark_node;
2147
2148   /* If ARRAY is a COMPOUND_EXPR or COND_EXPR, move our reference
2149      inside it.  */
2150   switch (TREE_CODE (array))
2151     {
2152     case COMPOUND_EXPR:
2153       {
2154         tree value = build_array_ref (TREE_OPERAND (array, 1), idx);
2155         return build2 (COMPOUND_EXPR, TREE_TYPE (value),
2156                        TREE_OPERAND (array, 0), value);
2157       }
2158
2159     case COND_EXPR:
2160       return build_conditional_expr
2161         (TREE_OPERAND (array, 0),
2162          build_array_ref (TREE_OPERAND (array, 1), idx),
2163          build_array_ref (TREE_OPERAND (array, 2), idx));
2164
2165     default:
2166       break;
2167     }
2168
2169   if (TREE_CODE (TREE_TYPE (array)) == ARRAY_TYPE)
2170     {
2171       tree rval, type;
2172
2173       /* Subscripting with type char is likely to lose
2174          on a machine where chars are signed.
2175          So warn on any machine, but optionally.
2176          Don't warn for unsigned char since that type is safe.
2177          Don't warn for signed char because anyone who uses that
2178          must have done so deliberately.  */
2179       if (warn_char_subscripts
2180           && TYPE_MAIN_VARIANT (TREE_TYPE (idx)) == char_type_node)
2181         warning ("array subscript has type %<char%>");
2182
2183       if (!INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (idx)))
2184         {
2185           error ("array subscript is not an integer");
2186           return error_mark_node;
2187         }
2188
2189       /* Apply integral promotions *after* noticing character types.
2190          (It is unclear why we do these promotions -- the standard
2191          does not say that we should.  In fact, the natual thing would
2192          seem to be to convert IDX to ptrdiff_t; we're performing
2193          pointer arithmetic.)  */
2194       idx = perform_integral_promotions (idx);
2195
2196       /* An array that is indexed by a non-constant
2197          cannot be stored in a register; we must be able to do
2198          address arithmetic on its address.
2199          Likewise an array of elements of variable size.  */
2200       if (TREE_CODE (idx) != INTEGER_CST
2201           || (COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (array)))
2202               && (TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (array))))
2203                   != INTEGER_CST)))
2204         {
2205           if (!cxx_mark_addressable (array))
2206             return error_mark_node;
2207         }
2208
2209       /* An array that is indexed by a constant value which is not within
2210          the array bounds cannot be stored in a register either; because we
2211          would get a crash in store_bit_field/extract_bit_field when trying
2212          to access a non-existent part of the register.  */
2213       if (TREE_CODE (idx) == INTEGER_CST
2214           && TYPE_DOMAIN (TREE_TYPE (array))
2215           && ! int_fits_type_p (idx, TYPE_DOMAIN (TREE_TYPE (array))))
2216         {
2217           if (!cxx_mark_addressable (array))
2218             return error_mark_node;
2219         }
2220
2221       if (pedantic && !lvalue_p (array))
2222         pedwarn ("ISO C++ forbids subscripting non-lvalue array");
2223
2224       /* Note in C++ it is valid to subscript a `register' array, since
2225          it is valid to take the address of something with that
2226          storage specification.  */
2227       if (extra_warnings)
2228         {
2229           tree foo = array;
2230           while (TREE_CODE (foo) == COMPONENT_REF)
2231             foo = TREE_OPERAND (foo, 0);
2232           if (TREE_CODE (foo) == VAR_DECL && DECL_REGISTER (foo))
2233             warning ("subscripting array declared %<register%>");
2234         }
2235
2236       type = TREE_TYPE (TREE_TYPE (array));
2237       rval = build4 (ARRAY_REF, type, array, idx, NULL_TREE, NULL_TREE);
2238       /* Array ref is const/volatile if the array elements are
2239          or if the array is..  */
2240       TREE_READONLY (rval)
2241         |= (CP_TYPE_CONST_P (type) | TREE_READONLY (array));
2242       TREE_SIDE_EFFECTS (rval)
2243         |= (CP_TYPE_VOLATILE_P (type) | TREE_SIDE_EFFECTS (array));
2244       TREE_THIS_VOLATILE (rval)
2245         |= (CP_TYPE_VOLATILE_P (type) | TREE_THIS_VOLATILE (array));
2246       return require_complete_type (fold_if_not_in_template (rval));
2247     }
2248
2249   {
2250     tree ar = default_conversion (array);
2251     tree ind = default_conversion (idx);
2252
2253     /* Put the integer in IND to simplify error checking.  */
2254     if (TREE_CODE (TREE_TYPE (ar)) == INTEGER_TYPE)
2255       {
2256         tree temp = ar;
2257         ar = ind;
2258         ind = temp;
2259       }
2260
2261     if (ar == error_mark_node)
2262       return ar;
2263
2264     if (TREE_CODE (TREE_TYPE (ar)) != POINTER_TYPE)
2265       {
2266         error ("subscripted value is neither array nor pointer");
2267         return error_mark_node;
2268       }
2269     if (TREE_CODE (TREE_TYPE (ind)) != INTEGER_TYPE)
2270       {
2271         error ("array subscript is not an integer");
2272         return error_mark_node;
2273       }
2274
2275     return build_indirect_ref (cp_build_binary_op (PLUS_EXPR, ar, ind),
2276                                "array indexing");
2277   }
2278 }
2279 \f
2280 /* Resolve a pointer to member function.  INSTANCE is the object
2281    instance to use, if the member points to a virtual member.
2282
2283    This used to avoid checking for virtual functions if basetype
2284    has no virtual functions, according to an earlier ANSI draft.
2285    With the final ISO C++ rules, such an optimization is
2286    incorrect: A pointer to a derived member can be static_cast
2287    to pointer-to-base-member, as long as the dynamic object
2288    later has the right member.  */
2289
2290 tree
2291 get_member_function_from_ptrfunc (tree *instance_ptrptr, tree function)
2292 {
2293   if (TREE_CODE (function) == OFFSET_REF)
2294     function = TREE_OPERAND (function, 1);
2295
2296   if (TYPE_PTRMEMFUNC_P (TREE_TYPE (function)))
2297     {
2298       tree idx, delta, e1, e2, e3, vtbl, basetype;
2299       tree fntype = TYPE_PTRMEMFUNC_FN_TYPE (TREE_TYPE (function));
2300
2301       tree instance_ptr = *instance_ptrptr;
2302       tree instance_save_expr = 0;
2303       if (instance_ptr == error_mark_node)
2304         {
2305           if (TREE_CODE (function) == PTRMEM_CST)
2306             {
2307               /* Extracting the function address from a pmf is only
2308                  allowed with -Wno-pmf-conversions. It only works for
2309                  pmf constants.  */
2310               e1 = build_addr_func (PTRMEM_CST_MEMBER (function));
2311               e1 = convert (fntype, e1);
2312               return e1;
2313             }
2314           else
2315             {
2316               error ("object missing in use of %qE", function);
2317               return error_mark_node;
2318             }
2319         }
2320
2321       if (TREE_SIDE_EFFECTS (instance_ptr))
2322         instance_ptr = instance_save_expr = save_expr (instance_ptr);
2323
2324       if (TREE_SIDE_EFFECTS (function))
2325         function = save_expr (function);
2326
2327       /* Start by extracting all the information from the PMF itself.  */
2328       e3 = PFN_FROM_PTRMEMFUNC (function);
2329       delta = build_ptrmemfunc_access_expr (function, delta_identifier);
2330       idx = build1 (NOP_EXPR, vtable_index_type, e3);
2331       switch (TARGET_PTRMEMFUNC_VBIT_LOCATION)
2332         {
2333         case ptrmemfunc_vbit_in_pfn:
2334           e1 = cp_build_binary_op (BIT_AND_EXPR, idx, integer_one_node);
2335           idx = cp_build_binary_op (MINUS_EXPR, idx, integer_one_node);
2336           break;
2337
2338         case ptrmemfunc_vbit_in_delta:
2339           e1 = cp_build_binary_op (BIT_AND_EXPR, delta, integer_one_node);
2340           delta = cp_build_binary_op (RSHIFT_EXPR, delta, integer_one_node);
2341           break;
2342
2343         default:
2344           gcc_unreachable ();
2345         }
2346
2347       /* Convert down to the right base before using the instance.  First
2348          use the type...  */
2349       basetype = TYPE_METHOD_BASETYPE (TREE_TYPE (fntype));
2350       basetype = lookup_base (TREE_TYPE (TREE_TYPE (instance_ptr)),
2351                               basetype, ba_check, NULL);
2352       instance_ptr = build_base_path (PLUS_EXPR, instance_ptr, basetype, 1);
2353       if (instance_ptr == error_mark_node)
2354         return error_mark_node;
2355       /* ...and then the delta in the PMF.  */
2356       instance_ptr = build2 (PLUS_EXPR, TREE_TYPE (instance_ptr),
2357                              instance_ptr, delta);
2358
2359       /* Hand back the adjusted 'this' argument to our caller.  */
2360       *instance_ptrptr = instance_ptr;
2361
2362       /* Next extract the vtable pointer from the object.  */
2363       vtbl = build1 (NOP_EXPR, build_pointer_type (vtbl_ptr_type_node),
2364                      instance_ptr);
2365       vtbl = build_indirect_ref (vtbl, NULL);
2366
2367       /* Finally, extract the function pointer from the vtable.  */
2368       e2 = fold (build2 (PLUS_EXPR, TREE_TYPE (vtbl), vtbl, idx));
2369       e2 = build_indirect_ref (e2, NULL);
2370       TREE_CONSTANT (e2) = 1;
2371       TREE_INVARIANT (e2) = 1;
2372
2373       /* When using function descriptors, the address of the
2374          vtable entry is treated as a function pointer.  */
2375       if (TARGET_VTABLE_USES_DESCRIPTORS)
2376         e2 = build1 (NOP_EXPR, TREE_TYPE (e2),
2377                      build_unary_op (ADDR_EXPR, e2, /*noconvert=*/1));
2378
2379       TREE_TYPE (e2) = TREE_TYPE (e3);
2380       e1 = build_conditional_expr (e1, e2, e3);
2381
2382       /* Make sure this doesn't get evaluated first inside one of the
2383          branches of the COND_EXPR.  */
2384       if (instance_save_expr)
2385         e1 = build2 (COMPOUND_EXPR, TREE_TYPE (e1),
2386                      instance_save_expr, e1);
2387
2388       function = e1;
2389     }
2390   return function;
2391 }
2392
2393 tree
2394 build_function_call (tree function, tree params)
2395 {
2396   tree fntype, fndecl;
2397   tree coerced_params;
2398   tree name = NULL_TREE;
2399   int is_method;
2400   tree original = function;
2401
2402   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
2403      Strip such NOP_EXPRs, since FUNCTION is used in non-lvalue context.  */
2404   if (TREE_CODE (function) == NOP_EXPR
2405       && TREE_TYPE (function) == TREE_TYPE (TREE_OPERAND (function, 0)))
2406     function = TREE_OPERAND (function, 0);
2407
2408   if (TREE_CODE (function) == FUNCTION_DECL)
2409     {
2410       name = DECL_NAME (function);
2411
2412       mark_used (function);
2413       fndecl = function;
2414
2415       /* Convert anything with function type to a pointer-to-function.  */
2416       if (pedantic && DECL_MAIN_P (function))
2417         pedwarn ("ISO C++ forbids calling %<::main%> from within program");
2418
2419       /* Differs from default_conversion by not setting TREE_ADDRESSABLE
2420          (because calling an inline function does not mean the function
2421          needs to be separately compiled).  */
2422
2423       if (DECL_INLINE (function))
2424         function = inline_conversion (function);
2425       else
2426         function = build_addr_func (function);
2427     }
2428   else
2429     {
2430       fndecl = NULL_TREE;
2431
2432       function = build_addr_func (function);
2433     }
2434
2435   if (function == error_mark_node)
2436     return error_mark_node;
2437
2438   fntype = TREE_TYPE (function);
2439
2440   if (TYPE_PTRMEMFUNC_P (fntype))
2441     {
2442       error ("must use %<.*%> or %<->*%> to call pointer-to-member "
2443              "function in %<%E (...)%>",
2444              original);
2445       return error_mark_node;
2446     }
2447
2448   is_method = (TREE_CODE (fntype) == POINTER_TYPE
2449                && TREE_CODE (TREE_TYPE (fntype)) == METHOD_TYPE);
2450
2451   if (!((TREE_CODE (fntype) == POINTER_TYPE
2452          && TREE_CODE (TREE_TYPE (fntype)) == FUNCTION_TYPE)
2453         || is_method
2454         || TREE_CODE (function) == TEMPLATE_ID_EXPR))
2455     {
2456       error ("%qE cannot be used as a function", original);
2457       return error_mark_node;
2458     }
2459
2460   /* fntype now gets the type of function pointed to.  */
2461   fntype = TREE_TYPE (fntype);
2462
2463   /* Convert the parameters to the types declared in the
2464      function prototype, or apply default promotions.  */
2465
2466   coerced_params = convert_arguments (TYPE_ARG_TYPES (fntype),
2467                                       params, fndecl, LOOKUP_NORMAL);
2468   if (coerced_params == error_mark_node)
2469     return error_mark_node;
2470
2471   /* Check for errors in format strings and inappropriately
2472      null parameters.  */
2473
2474   check_function_arguments (TYPE_ATTRIBUTES (fntype), coerced_params);
2475
2476   return build_cxx_call (function, coerced_params);
2477 }
2478 \f
2479 /* Convert the actual parameter expressions in the list VALUES
2480    to the types in the list TYPELIST.
2481    If parmdecls is exhausted, or when an element has NULL as its type,
2482    perform the default conversions.
2483
2484    NAME is an IDENTIFIER_NODE or 0.  It is used only for error messages.
2485
2486    This is also where warnings about wrong number of args are generated.
2487
2488    Return a list of expressions for the parameters as converted.
2489
2490    Both VALUES and the returned value are chains of TREE_LIST nodes
2491    with the elements of the list in the TREE_VALUE slots of those nodes.
2492
2493    In C++, unspecified trailing parameters can be filled in with their
2494    default arguments, if such were specified.  Do so here.  */
2495
2496 tree
2497 convert_arguments (tree typelist, tree values, tree fndecl, int flags)
2498 {
2499   tree typetail, valtail;
2500   tree result = NULL_TREE;
2501   const char *called_thing = 0;
2502   int i = 0;
2503
2504   /* Argument passing is always copy-initialization.  */
2505   flags |= LOOKUP_ONLYCONVERTING;
2506
2507   if (fndecl)
2508     {
2509       if (TREE_CODE (TREE_TYPE (fndecl)) == METHOD_TYPE)
2510         {
2511           if (DECL_NAME (fndecl) == NULL_TREE
2512               || IDENTIFIER_HAS_TYPE_VALUE (DECL_NAME (fndecl)))
2513             called_thing = "constructor";
2514           else
2515             called_thing = "member function";
2516         }
2517       else
2518         called_thing = "function";
2519     }
2520
2521   for (valtail = values, typetail = typelist;
2522        valtail;
2523        valtail = TREE_CHAIN (valtail), i++)
2524     {
2525       tree type = typetail ? TREE_VALUE (typetail) : 0;
2526       tree val = TREE_VALUE (valtail);
2527
2528       if (val == error_mark_node)
2529         return error_mark_node;
2530
2531       if (type == void_type_node)
2532         {
2533           if (fndecl)
2534             {
2535               cp_error_at ("too many arguments to %s %q+#D", called_thing,
2536                            fndecl);
2537               error ("at this point in file");
2538             }
2539           else
2540             error ("too many arguments to function");
2541           /* In case anybody wants to know if this argument
2542              list is valid.  */
2543           if (result)
2544             TREE_TYPE (tree_last (result)) = error_mark_node;
2545           break;
2546         }
2547
2548       /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
2549          Strip such NOP_EXPRs, since VAL is used in non-lvalue context.  */
2550       if (TREE_CODE (val) == NOP_EXPR
2551           && TREE_TYPE (val) == TREE_TYPE (TREE_OPERAND (val, 0))
2552           && (type == 0 || TREE_CODE (type) != REFERENCE_TYPE))
2553         val = TREE_OPERAND (val, 0);
2554
2555       if (type == 0 || TREE_CODE (type) != REFERENCE_TYPE)
2556         {
2557           if (TREE_CODE (TREE_TYPE (val)) == ARRAY_TYPE
2558               || TREE_CODE (TREE_TYPE (val)) == FUNCTION_TYPE
2559               || TREE_CODE (TREE_TYPE (val)) == METHOD_TYPE)
2560             val = decay_conversion (val);
2561         }
2562
2563       if (val == error_mark_node)
2564         return error_mark_node;
2565
2566       if (type != 0)
2567         {
2568           /* Formal parm type is specified by a function prototype.  */
2569           tree parmval;
2570
2571           if (!COMPLETE_TYPE_P (complete_type (type)))
2572             {
2573               if (fndecl)
2574                 error ("parameter %P of %qD has incomplete type %qT",
2575                        i, fndecl, type);
2576               else
2577                 error ("parameter %P has incomplete type %qT", i, type);
2578               parmval = error_mark_node;
2579             }
2580           else
2581             {
2582               parmval = convert_for_initialization
2583                 (NULL_TREE, type, val, flags,
2584                  "argument passing", fndecl, i);
2585               parmval = convert_for_arg_passing (type, parmval);
2586             }
2587
2588           if (parmval == error_mark_node)
2589             return error_mark_node;
2590
2591           result = tree_cons (NULL_TREE, parmval, result);
2592         }
2593       else
2594         {
2595           if (fndecl && DECL_BUILT_IN (fndecl)
2596               && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_CONSTANT_P)
2597             /* Don't do ellipsis conversion for __built_in_constant_p
2598                as this will result in spurious warnings for non-POD
2599                types.  */
2600             val = require_complete_type (val);
2601           else
2602             val = convert_arg_to_ellipsis (val);
2603
2604           result = tree_cons (NULL_TREE, val, result);
2605         }
2606
2607       if (typetail)
2608         typetail = TREE_CHAIN (typetail);
2609     }
2610
2611   if (typetail != 0 && typetail != void_list_node)
2612     {
2613       /* See if there are default arguments that can be used.  */
2614       if (TREE_PURPOSE (typetail)
2615           && TREE_CODE (TREE_PURPOSE (typetail)) != DEFAULT_ARG)
2616         {
2617           for (; typetail != void_list_node; ++i)
2618             {
2619               tree parmval
2620                 = convert_default_arg (TREE_VALUE (typetail),
2621                                        TREE_PURPOSE (typetail),
2622                                        fndecl, i);
2623
2624               if (parmval == error_mark_node)
2625                 return error_mark_node;
2626
2627               result = tree_cons (0, parmval, result);
2628               typetail = TREE_CHAIN (typetail);
2629               /* ends with `...'.  */
2630               if (typetail == NULL_TREE)
2631                 break;
2632             }
2633         }
2634       else
2635         {
2636           if (fndecl)
2637             {
2638               cp_error_at ("too few arguments to %s %q+#D",
2639                            called_thing, fndecl);
2640               error ("at this point in file");
2641             }
2642           else
2643             error ("too few arguments to function");
2644           return error_mark_list;
2645         }
2646     }
2647
2648   return nreverse (result);
2649 }
2650 \f
2651 /* Build a binary-operation expression, after performing default
2652    conversions on the operands.  CODE is the kind of expression to build.  */
2653
2654 tree
2655 build_x_binary_op (enum tree_code code, tree arg1, tree arg2,
2656                    bool *overloaded_p)
2657 {
2658   tree orig_arg1;
2659   tree orig_arg2;
2660   tree expr;
2661
2662   orig_arg1 = arg1;
2663   orig_arg2 = arg2;
2664
2665   if (processing_template_decl)
2666     {
2667       if (type_dependent_expression_p (arg1)
2668           || type_dependent_expression_p (arg2))
2669         return build_min_nt (code, arg1, arg2);
2670       arg1 = build_non_dependent_expr (arg1);
2671       arg2 = build_non_dependent_expr (arg2);
2672     }
2673
2674   if (code == DOTSTAR_EXPR)
2675     expr = build_m_component_ref (arg1, arg2);
2676   else
2677     expr = build_new_op (code, LOOKUP_NORMAL, arg1, arg2, NULL_TREE,
2678                          overloaded_p);
2679
2680   if (processing_template_decl && expr != error_mark_node)
2681     return build_min_non_dep (code, expr, orig_arg1, orig_arg2);
2682
2683   return expr;
2684 }
2685
2686 /* Build a binary-operation expression without default conversions.
2687    CODE is the kind of expression to build.
2688    This function differs from `build' in several ways:
2689    the data type of the result is computed and recorded in it,
2690    warnings are generated if arg data types are invalid,
2691    special handling for addition and subtraction of pointers is known,
2692    and some optimization is done (operations on narrow ints
2693    are done in the narrower type when that gives the same result).
2694    Constant folding is also done before the result is returned.
2695
2696    Note that the operands will never have enumeral types
2697    because either they have just had the default conversions performed
2698    or they have both just been converted to some other type in which
2699    the arithmetic is to be done.
2700
2701    C++: must do special pointer arithmetic when implementing
2702    multiple inheritance, and deal with pointer to member functions.  */
2703
2704 tree
2705 build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
2706                  int convert_p ATTRIBUTE_UNUSED)
2707 {
2708   tree op0, op1;
2709   enum tree_code code0, code1;
2710   tree type0, type1;
2711
2712   /* Expression code to give to the expression when it is built.
2713      Normally this is CODE, which is what the caller asked for,
2714      but in some special cases we change it.  */
2715   enum tree_code resultcode = code;
2716
2717   /* Data type in which the computation is to be performed.
2718      In the simplest cases this is the common type of the arguments.  */
2719   tree result_type = NULL;
2720
2721   /* Nonzero means operands have already been type-converted
2722      in whatever way is necessary.
2723      Zero means they need to be converted to RESULT_TYPE.  */
2724   int converted = 0;
2725
2726   /* Nonzero means create the expression with this type, rather than
2727      RESULT_TYPE.  */
2728   tree build_type = 0;
2729
2730   /* Nonzero means after finally constructing the expression
2731      convert it to this type.  */
2732   tree final_type = 0;
2733
2734   tree result;
2735
2736   /* Nonzero if this is an operation like MIN or MAX which can
2737      safely be computed in short if both args are promoted shorts.
2738      Also implies COMMON.
2739      -1 indicates a bitwise operation; this makes a difference
2740      in the exact conditions for when it is safe to do the operation
2741      in a narrower mode.  */
2742   int shorten = 0;
2743
2744   /* Nonzero if this is a comparison operation;
2745      if both args are promoted shorts, compare the original shorts.
2746      Also implies COMMON.  */
2747   int short_compare = 0;
2748
2749   /* Nonzero if this is a right-shift operation, which can be computed on the
2750      original short and then promoted if the operand is a promoted short.  */
2751   int short_shift = 0;
2752
2753   /* Nonzero means set RESULT_TYPE to the common type of the args.  */
2754   int common = 0;
2755
2756   /* True if both operands have arithmetic type.  */
2757   bool arithmetic_types_p;
2758
2759   /* Apply default conversions.  */
2760   op0 = orig_op0;
2761   op1 = orig_op1;
2762
2763   if (code == TRUTH_AND_EXPR || code == TRUTH_ANDIF_EXPR
2764       || code == TRUTH_OR_EXPR || code == TRUTH_ORIF_EXPR
2765       || code == TRUTH_XOR_EXPR)
2766     {
2767       if (!really_overloaded_fn (op0))
2768         op0 = decay_conversion (op0);
2769       if (!really_overloaded_fn (op1))
2770         op1 = decay_conversion (op1);
2771     }
2772   else
2773     {
2774       if (!really_overloaded_fn (op0))
2775         op0 = default_conversion (op0);
2776       if (!really_overloaded_fn (op1))
2777         op1 = default_conversion (op1);
2778     }
2779
2780   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
2781   STRIP_TYPE_NOPS (op0);
2782   STRIP_TYPE_NOPS (op1);
2783
2784   /* DTRT if one side is an overloaded function, but complain about it.  */
2785   if (type_unknown_p (op0))
2786     {
2787       tree t = instantiate_type (TREE_TYPE (op1), op0, tf_none);
2788       if (t != error_mark_node)
2789         {
2790           pedwarn ("assuming cast to type %qT from overloaded function",
2791                    TREE_TYPE (t));
2792           op0 = t;
2793         }
2794     }
2795   if (type_unknown_p (op1))
2796     {
2797       tree t = instantiate_type (TREE_TYPE (op0), op1, tf_none);
2798       if (t != error_mark_node)
2799         {
2800           pedwarn ("assuming cast to type %qT from overloaded function",
2801                    TREE_TYPE (t));
2802           op1 = t;
2803         }
2804     }
2805
2806   type0 = TREE_TYPE (op0);
2807   type1 = TREE_TYPE (op1);
2808
2809   /* The expression codes of the data types of the arguments tell us
2810      whether the arguments are integers, floating, pointers, etc.  */
2811   code0 = TREE_CODE (type0);
2812   code1 = TREE_CODE (type1);
2813
2814   /* If an error was already reported for one of the arguments,
2815      avoid reporting another error.  */
2816
2817   if (code0 == ERROR_MARK || code1 == ERROR_MARK)
2818     return error_mark_node;
2819
2820   switch (code)
2821     {
2822     case PLUS_EXPR:
2823       /* Handle the pointer + int case.  */
2824       if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
2825         return cp_pointer_int_sum (PLUS_EXPR, op0, op1);
2826       else if (code1 == POINTER_TYPE && code0 == INTEGER_TYPE)
2827         return cp_pointer_int_sum (PLUS_EXPR, op1, op0);
2828       else
2829         common = 1;
2830       break;
2831
2832     case MINUS_EXPR:
2833       /* Subtraction of two similar pointers.
2834          We must subtract them as integers, then divide by object size.  */
2835       if (code0 == POINTER_TYPE && code1 == POINTER_TYPE
2836           && same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (type0),
2837                                                         TREE_TYPE (type1)))
2838         return pointer_diff (op0, op1, common_type (type0, type1));
2839       /* Handle pointer minus int.  Just like pointer plus int.  */
2840       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
2841         return cp_pointer_int_sum (MINUS_EXPR, op0, op1);
2842       else
2843         common = 1;
2844       break;
2845
2846     case MULT_EXPR:
2847       common = 1;
2848       break;
2849
2850     case TRUNC_DIV_EXPR:
2851     case CEIL_DIV_EXPR:
2852     case FLOOR_DIV_EXPR:
2853     case ROUND_DIV_EXPR:
2854     case EXACT_DIV_EXPR:
2855       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
2856            || code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
2857           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
2858               || code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE))
2859         {
2860           if (TREE_CODE (op1) == INTEGER_CST && integer_zerop (op1))
2861             warning ("division by zero in %<%E / 0%>", op0);
2862           else if (TREE_CODE (op1) == REAL_CST && real_zerop (op1))
2863             warning ("division by zero in %<%E / 0.%>", op0);
2864
2865           if (code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
2866             code0 = TREE_CODE (TREE_TYPE (TREE_TYPE (op0)));
2867           if (code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE)
2868             code1 = TREE_CODE (TREE_TYPE (TREE_TYPE (op1)));
2869
2870           if (!(code0 == INTEGER_TYPE && code1 == INTEGER_TYPE))
2871             resultcode = RDIV_EXPR;
2872           else
2873             /* When dividing two signed integers, we have to promote to int.
2874                unless we divide by a constant != -1.  Note that default
2875                conversion will have been performed on the operands at this
2876                point, so we have to dig out the original type to find out if
2877                it was unsigned.  */
2878             shorten = ((TREE_CODE (op0) == NOP_EXPR
2879                         && TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op0, 0))))
2880                        || (TREE_CODE (op1) == INTEGER_CST
2881                            && ! integer_all_onesp (op1)));
2882
2883           common = 1;
2884         }
2885       break;
2886
2887     case BIT_AND_EXPR:
2888     case BIT_IOR_EXPR:
2889     case BIT_XOR_EXPR:
2890       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2891         shorten = -1;
2892       break;
2893
2894     case TRUNC_MOD_EXPR:
2895     case FLOOR_MOD_EXPR:
2896       if (code1 == INTEGER_TYPE && integer_zerop (op1))
2897         warning ("division by zero in %<%E %% 0%>", op0);
2898       else if (code1 == REAL_TYPE && real_zerop (op1))
2899         warning ("division by zero in %<%E %% 0.%>", op0);
2900
2901       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2902         {
2903           /* Although it would be tempting to shorten always here, that loses
2904              on some targets, since the modulo instruction is undefined if the
2905              quotient can't be represented in the computation mode.  We shorten
2906              only if unsigned or if dividing by something we know != -1.  */
2907           shorten = ((TREE_CODE (op0) == NOP_EXPR
2908                       && TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op0, 0))))
2909                      || (TREE_CODE (op1) == INTEGER_CST
2910                          && ! integer_all_onesp (op1)));
2911           common = 1;
2912         }
2913       break;
2914
2915     case TRUTH_ANDIF_EXPR:
2916     case TRUTH_ORIF_EXPR:
2917     case TRUTH_AND_EXPR:
2918     case TRUTH_OR_EXPR:
2919       result_type = boolean_type_node;
2920       break;
2921
2922       /* Shift operations: result has same type as first operand;
2923          always convert second operand to int.
2924          Also set SHORT_SHIFT if shifting rightward.  */
2925
2926     case RSHIFT_EXPR:
2927       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2928         {
2929           result_type = type0;
2930           if (TREE_CODE (op1) == INTEGER_CST)
2931             {
2932               if (tree_int_cst_lt (op1, integer_zero_node))
2933                 warning ("right shift count is negative");
2934               else
2935                 {
2936                   if (! integer_zerop (op1))
2937                     short_shift = 1;
2938                   if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
2939                     warning ("right shift count >= width of type");
2940                 }
2941             }
2942           /* Convert the shift-count to an integer, regardless of
2943              size of value being shifted.  */
2944           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
2945             op1 = cp_convert (integer_type_node, op1);
2946           /* Avoid converting op1 to result_type later.  */
2947           converted = 1;
2948         }
2949       break;
2950
2951     case LSHIFT_EXPR:
2952       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2953         {
2954           result_type = type0;
2955           if (TREE_CODE (op1) == INTEGER_CST)
2956             {
2957               if (tree_int_cst_lt (op1, integer_zero_node))
2958                 warning ("left shift count is negative");
2959               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
2960                 warning ("left shift count >= width of type");
2961             }
2962           /* Convert the shift-count to an integer, regardless of
2963              size of value being shifted.  */
2964           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
2965             op1 = cp_convert (integer_type_node, op1);
2966           /* Avoid converting op1 to result_type later.  */
2967           converted = 1;
2968         }
2969       break;
2970
2971     case RROTATE_EXPR:
2972     case LROTATE_EXPR:
2973       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2974         {
2975           result_type = type0;
2976           if (TREE_CODE (op1) == INTEGER_CST)
2977             {
2978               if (tree_int_cst_lt (op1, integer_zero_node))
2979                 warning ("%s rotate count is negative",
2980                          (code == LROTATE_EXPR) ? "left" : "right");
2981               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
2982                 warning ("%s rotate count >= width of type",
2983                          (code == LROTATE_EXPR) ? "left" : "right");
2984             }
2985           /* Convert the shift-count to an integer, regardless of
2986              size of value being shifted.  */
2987           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
2988             op1 = cp_convert (integer_type_node, op1);
2989         }
2990       break;
2991
2992     case EQ_EXPR:
2993     case NE_EXPR:
2994       if (warn_float_equal && (code0 == REAL_TYPE || code1 == REAL_TYPE))
2995         warning ("comparing floating point with == or != is unsafe");
2996
2997       build_type = boolean_type_node;
2998       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
2999            || code0 == COMPLEX_TYPE)
3000           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
3001               || code1 == COMPLEX_TYPE))
3002         short_compare = 1;
3003       else if ((code0 == POINTER_TYPE && code1 == POINTER_TYPE)
3004                || (TYPE_PTRMEM_P (type0) && TYPE_PTRMEM_P (type1)))
3005         result_type = composite_pointer_type (type0, type1, op0, op1,
3006                                               "comparison");
3007       else if ((code0 == POINTER_TYPE || TYPE_PTRMEM_P (type0))
3008                && null_ptr_cst_p (op1))
3009         result_type = type0;
3010       else if ((code1 == POINTER_TYPE || TYPE_PTRMEM_P (type1))
3011                && null_ptr_cst_p (op0))
3012         result_type = type1;
3013       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
3014         {
3015           result_type = type0;
3016           error ("ISO C++ forbids comparison between pointer and integer");
3017         }
3018       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
3019         {
3020           result_type = type1;
3021           error ("ISO C++ forbids comparison between pointer and integer");
3022         }
3023       else if (TYPE_PTRMEMFUNC_P (type0) && null_ptr_cst_p (op1))
3024         {
3025           op0 = build_ptrmemfunc_access_expr (op0, pfn_identifier);
3026           op1 = cp_convert (TREE_TYPE (op0), integer_zero_node);
3027           result_type = TREE_TYPE (op0);
3028         }
3029       else if (TYPE_PTRMEMFUNC_P (type1) && null_ptr_cst_p (op0))
3030         return cp_build_binary_op (code, op1, op0);
3031       else if (TYPE_PTRMEMFUNC_P (type0) && TYPE_PTRMEMFUNC_P (type1)
3032                && same_type_p (type0, type1))
3033         {
3034           /* E will be the final comparison.  */
3035           tree e;
3036           /* E1 and E2 are for scratch.  */
3037           tree e1;
3038           tree e2;
3039           tree pfn0;
3040           tree pfn1;
3041           tree delta0;
3042           tree delta1;
3043
3044           if (TREE_SIDE_EFFECTS (op0))
3045             op0 = save_expr (op0);
3046           if (TREE_SIDE_EFFECTS (op1))
3047             op1 = save_expr (op1);
3048
3049           /* We generate:
3050
3051              (op0.pfn == op1.pfn
3052               && (!op0.pfn || op0.delta == op1.delta))
3053
3054              The reason for the `!op0.pfn' bit is that a NULL
3055              pointer-to-member is any member with a zero PFN; the
3056              DELTA field is unspecified.  */
3057           pfn0 = pfn_from_ptrmemfunc (op0);
3058           pfn1 = pfn_from_ptrmemfunc (op1);
3059           delta0 = build_ptrmemfunc_access_expr (op0,
3060                                                  delta_identifier);
3061           delta1 = build_ptrmemfunc_access_expr (op1,
3062                                                  delta_identifier);
3063           e1 = cp_build_binary_op (EQ_EXPR, delta0, delta1);
3064           e2 = cp_build_binary_op (EQ_EXPR,
3065                                    pfn0,
3066                                    cp_convert (TREE_TYPE (pfn0),
3067                                                integer_zero_node));
3068           e1 = cp_build_binary_op (TRUTH_ORIF_EXPR, e1, e2);
3069           e2 = build2 (EQ_EXPR, boolean_type_node, pfn0, pfn1);
3070           e = cp_build_binary_op (TRUTH_ANDIF_EXPR, e2, e1);
3071           if (code == EQ_EXPR)
3072             return e;
3073           return cp_build_binary_op (EQ_EXPR, e, integer_zero_node);
3074         }
3075       else
3076         {
3077           gcc_assert (!TYPE_PTRMEMFUNC_P (type0)
3078                       || !same_type_p (TYPE_PTRMEMFUNC_FN_TYPE (type0),
3079                                        type1));
3080           gcc_assert (!TYPE_PTRMEMFUNC_P (type1)
3081                       || !same_type_p (TYPE_PTRMEMFUNC_FN_TYPE (type1),
3082                                        type0));
3083         }
3084
3085       break;
3086
3087     case MAX_EXPR:
3088     case MIN_EXPR:
3089       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
3090            && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
3091         shorten = 1;
3092       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
3093         result_type = composite_pointer_type (type0, type1, op0, op1,
3094                                               "comparison");
3095       break;
3096
3097     case LE_EXPR:
3098     case GE_EXPR:
3099     case LT_EXPR:
3100     case GT_EXPR:
3101       build_type = boolean_type_node;
3102       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
3103            && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
3104         short_compare = 1;
3105       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
3106         result_type = composite_pointer_type (type0, type1, op0, op1,
3107                                               "comparison");
3108       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
3109                && integer_zerop (op1))
3110         result_type = type0;
3111       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
3112                && integer_zerop (op0))
3113         result_type = type1;
3114       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
3115         {
3116           result_type = type0;
3117           pedwarn ("ISO C++ forbids comparison between pointer and integer");
3118         }
3119       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
3120         {
3121           result_type = type1;
3122           pedwarn ("ISO C++ forbids comparison between pointer and integer");
3123         }
3124       break;
3125
3126     case UNORDERED_EXPR:
3127     case ORDERED_EXPR:
3128     case UNLT_EXPR:
3129     case UNLE_EXPR:
3130     case UNGT_EXPR:
3131     case UNGE_EXPR:
3132     case UNEQ_EXPR:
3133       build_type = integer_type_node;
3134       if (code0 != REAL_TYPE || code1 != REAL_TYPE)
3135         {
3136           error ("unordered comparison on non-floating point argument");
3137           return error_mark_node;
3138         }
3139       common = 1;
3140       break;
3141
3142     default:
3143       break;
3144     }
3145
3146   arithmetic_types_p =
3147     ((code0 == INTEGER_TYPE || code0 == REAL_TYPE || code0 == COMPLEX_TYPE)
3148      && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
3149          || code1 == COMPLEX_TYPE));
3150   /* Determine the RESULT_TYPE, if it is not already known.  */
3151   if (!result_type
3152       && arithmetic_types_p
3153       && (shorten || common || short_compare))
3154     result_type = common_type (type0, type1);
3155
3156   if (!result_type)
3157     {
3158       error ("invalid operands of types %qT and %qT to binary %qO",
3159              TREE_TYPE (orig_op0), TREE_TYPE (orig_op1), code);
3160       return error_mark_node;
3161     }
3162
3163   /* If we're in a template, the only thing we need to know is the
3164      RESULT_TYPE.  */
3165   if (processing_template_decl)
3166     return build2 (resultcode,
3167                    build_type ? build_type : result_type,
3168                    op0, op1);
3169
3170   if (arithmetic_types_p)
3171     {
3172       int none_complex = (code0 != COMPLEX_TYPE && code1 != COMPLEX_TYPE);
3173
3174       /* For certain operations (which identify themselves by shorten != 0)
3175          if both args were extended from the same smaller type,
3176          do the arithmetic in that type and then extend.
3177
3178          shorten !=0 and !=1 indicates a bitwise operation.
3179          For them, this optimization is safe only if
3180          both args are zero-extended or both are sign-extended.
3181          Otherwise, we might change the result.
3182          Eg, (short)-1 | (unsigned short)-1 is (int)-1
3183          but calculated in (unsigned short) it would be (unsigned short)-1.  */
3184
3185       if (shorten && none_complex)
3186         {
3187           int unsigned0, unsigned1;
3188           tree arg0 = get_narrower (op0, &unsigned0);
3189           tree arg1 = get_narrower (op1, &unsigned1);
3190           /* UNS is 1 if the operation to be done is an unsigned one.  */
3191           int uns = TYPE_UNSIGNED (result_type);
3192           tree type;
3193
3194           final_type = result_type;
3195
3196           /* Handle the case that OP0 does not *contain* a conversion
3197              but it *requires* conversion to FINAL_TYPE.  */
3198
3199           if (op0 == arg0 && TREE_TYPE (op0) != final_type)
3200             unsigned0 = TYPE_UNSIGNED (TREE_TYPE (op0));
3201           if (op1 == arg1 && TREE_TYPE (op1) != final_type)
3202             unsigned1 = TYPE_UNSIGNED (TREE_TYPE (op1));
3203
3204           /* Now UNSIGNED0 is 1 if ARG0 zero-extends to FINAL_TYPE.  */
3205
3206           /* For bitwise operations, signedness of nominal type
3207              does not matter.  Consider only how operands were extended.  */
3208           if (shorten == -1)
3209             uns = unsigned0;
3210
3211           /* Note that in all three cases below we refrain from optimizing
3212              an unsigned operation on sign-extended args.
3213              That would not be valid.  */
3214
3215           /* Both args variable: if both extended in same way
3216              from same width, do it in that width.
3217              Do it unsigned if args were zero-extended.  */
3218           if ((TYPE_PRECISION (TREE_TYPE (arg0))
3219                < TYPE_PRECISION (result_type))
3220               && (TYPE_PRECISION (TREE_TYPE (arg1))
3221                   == TYPE_PRECISION (TREE_TYPE (arg0)))
3222               && unsigned0 == unsigned1
3223               && (unsigned0 || !uns))
3224             result_type = c_common_signed_or_unsigned_type
3225               (unsigned0, common_type (TREE_TYPE (arg0), TREE_TYPE (arg1)));
3226           else if (TREE_CODE (arg0) == INTEGER_CST
3227                    && (unsigned1 || !uns)
3228                    && (TYPE_PRECISION (TREE_TYPE (arg1))
3229                        < TYPE_PRECISION (result_type))
3230                    && (type = c_common_signed_or_unsigned_type
3231                        (unsigned1, TREE_TYPE (arg1)),
3232                        int_fits_type_p (arg0, type)))
3233             result_type = type;
3234           else if (TREE_CODE (arg1) == INTEGER_CST
3235                    && (unsigned0 || !uns)
3236                    && (TYPE_PRECISION (TREE_TYPE (arg0))
3237                        < TYPE_PRECISION (result_type))
3238                    && (type = c_common_signed_or_unsigned_type
3239                        (unsigned0, TREE_TYPE (arg0)),
3240                        int_fits_type_p (arg1, type)))
3241             result_type = type;
3242         }
3243
3244       /* Shifts can be shortened if shifting right.  */
3245
3246       if (short_shift)
3247         {
3248           int unsigned_arg;
3249           tree arg0 = get_narrower (op0, &unsigned_arg);
3250
3251           final_type = result_type;
3252
3253           if (arg0 == op0 && final_type == TREE_TYPE (op0))
3254             unsigned_arg = TYPE_UNSIGNED (TREE_TYPE (op0));
3255
3256           if (TYPE_PRECISION (TREE_TYPE (arg0)) < TYPE_PRECISION (result_type)
3257               /* We can shorten only if the shift count is less than the
3258                  number of bits in the smaller type size.  */
3259               && compare_tree_int (op1, TYPE_PRECISION (TREE_TYPE (arg0))) < 0
3260               /* If arg is sign-extended and then unsigned-shifted,
3261                  we can simulate this with a signed shift in arg's type
3262                  only if the extended result is at least twice as wide
3263                  as the arg.  Otherwise, the shift could use up all the
3264                  ones made by sign-extension and bring in zeros.
3265                  We can't optimize that case at all, but in most machines
3266                  it never happens because available widths are 2**N.  */
3267               && (!TYPE_UNSIGNED (final_type)
3268                   || unsigned_arg
3269                   || (((unsigned) 2 * TYPE_PRECISION (TREE_TYPE (arg0)))
3270                       <= TYPE_PRECISION (result_type))))
3271             {
3272               /* Do an unsigned shift if the operand was zero-extended.  */
3273               result_type
3274                 = c_common_signed_or_unsigned_type (unsigned_arg,
3275                                                     TREE_TYPE (arg0));
3276               /* Convert value-to-be-shifted to that type.  */
3277               if (TREE_TYPE (op0) != result_type)
3278                 op0 = cp_convert (result_type, op0);
3279               converted = 1;
3280             }
3281         }
3282
3283       /* Comparison operations are shortened too but differently.
3284          They identify themselves by setting short_compare = 1.  */
3285
3286       if (short_compare)
3287         {
3288           /* Don't write &op0, etc., because that would prevent op0
3289              from being kept in a register.
3290              Instead, make copies of the our local variables and
3291              pass the copies by reference, then copy them back afterward.  */
3292           tree xop0 = op0, xop1 = op1, xresult_type = result_type;
3293           enum tree_code xresultcode = resultcode;
3294           tree val
3295             = shorten_compare (&xop0, &xop1, &xresult_type, &xresultcode);
3296           if (val != 0)
3297             return cp_convert (boolean_type_node, val);
3298           op0 = xop0, op1 = xop1;
3299           converted = 1;
3300           resultcode = xresultcode;
3301         }
3302
3303       if ((short_compare || code == MIN_EXPR || code == MAX_EXPR)
3304           && warn_sign_compare
3305           /* Do not warn until the template is instantiated; we cannot
3306              bound the ranges of the arguments until that point.  */
3307           && !processing_template_decl)
3308         {
3309           int op0_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op0));
3310           int op1_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op1));
3311
3312           int unsignedp0, unsignedp1;
3313           tree primop0 = get_narrower (op0, &unsignedp0);
3314           tree primop1 = get_narrower (op1, &unsignedp1);
3315
3316           /* Check for comparison of different enum types.  */
3317           if (TREE_CODE (TREE_TYPE (orig_op0)) == ENUMERAL_TYPE
3318               && TREE_CODE (TREE_TYPE (orig_op1)) == ENUMERAL_TYPE
3319               && TYPE_MAIN_VARIANT (TREE_TYPE (orig_op0))
3320                  != TYPE_MAIN_VARIANT (TREE_TYPE (orig_op1)))
3321             {
3322               warning ("comparison between types %q#T and %q#T",
3323                        TREE_TYPE (orig_op0), TREE_TYPE (orig_op1));
3324             }
3325
3326           /* Give warnings for comparisons between signed and unsigned
3327              quantities that may fail.  */
3328           /* Do the checking based on the original operand trees, so that
3329              casts will be considered, but default promotions won't be.  */
3330
3331           /* Do not warn if the comparison is being done in a signed type,
3332              since the signed type will only be chosen if it can represent
3333              all the values of the unsigned type.  */
3334           if (!TYPE_UNSIGNED (result_type))
3335             /* OK */;
3336           /* Do not warn if both operands are unsigned.  */
3337           else if (op0_signed == op1_signed)
3338             /* OK */;
3339           /* Do not warn if the signed quantity is an unsuffixed
3340              integer literal (or some static constant expression
3341              involving such literals or a conditional expression
3342              involving such literals) and it is non-negative.  */
3343           else if ((op0_signed && tree_expr_nonnegative_p (orig_op0))
3344                    || (op1_signed && tree_expr_nonnegative_p (orig_op1)))
3345             /* OK */;
3346           /* Do not warn if the comparison is an equality operation,
3347              the unsigned quantity is an integral constant and it does
3348              not use the most significant bit of result_type.  */
3349           else if ((resultcode == EQ_EXPR || resultcode == NE_EXPR)
3350                    && ((op0_signed && TREE_CODE (orig_op1) == INTEGER_CST
3351                         && int_fits_type_p (orig_op1, c_common_signed_type
3352                                             (result_type)))
3353                         || (op1_signed && TREE_CODE (orig_op0) == INTEGER_CST
3354                             && int_fits_type_p (orig_op0, c_common_signed_type
3355                                                 (result_type)))))
3356             /* OK */;
3357           else
3358             warning ("comparison between signed and unsigned integer expressions");
3359
3360           /* Warn if two unsigned values are being compared in a size
3361              larger than their original size, and one (and only one) is the
3362              result of a `~' operator.  This comparison will always fail.
3363
3364              Also warn if one operand is a constant, and the constant does not
3365              have all bits set that are set in the ~ operand when it is
3366              extended.  */
3367
3368           if ((TREE_CODE (primop0) == BIT_NOT_EXPR)
3369               ^ (TREE_CODE (primop1) == BIT_NOT_EXPR))
3370             {
3371               if (TREE_CODE (primop0) == BIT_NOT_EXPR)
3372                 primop0 = get_narrower (TREE_OPERAND (op0, 0), &unsignedp0);
3373               if (TREE_CODE (primop1) == BIT_NOT_EXPR)
3374                 primop1 = get_narrower (TREE_OPERAND (op1, 0), &unsignedp1);
3375
3376               if (host_integerp (primop0, 0) || host_integerp (primop1, 0))
3377                 {
3378                   tree primop;
3379                   HOST_WIDE_INT constant, mask;
3380                   int unsignedp;
3381                   unsigned int bits;
3382
3383                   if (host_integerp (primop0, 0))
3384                     {
3385                       primop = primop1;
3386                       unsignedp = unsignedp1;
3387                       constant = tree_low_cst (primop0, 0);
3388                     }
3389                   else
3390                     {
3391                       primop = primop0;
3392                       unsignedp = unsignedp0;
3393                       constant = tree_low_cst (primop1, 0);
3394                     }
3395
3396                   bits = TYPE_PRECISION (TREE_TYPE (primop));
3397                   if (bits < TYPE_PRECISION (result_type)
3398                       && bits < HOST_BITS_PER_LONG && unsignedp)
3399                     {
3400                       mask = (~ (HOST_WIDE_INT) 0) << bits;
3401                       if ((mask & constant) != mask)
3402                         warning ("comparison of promoted ~unsigned with constant");
3403                     }
3404                 }
3405               else if (unsignedp0 && unsignedp1
3406                        && (TYPE_PRECISION (TREE_TYPE (primop0))
3407                            < TYPE_PRECISION (result_type))
3408                        && (TYPE_PRECISION (TREE_TYPE (primop1))
3409                            < TYPE_PRECISION (result_type)))
3410                 warning ("comparison of promoted ~unsigned with unsigned");
3411             }
3412         }
3413     }
3414
3415   /* If CONVERTED is zero, both args will be converted to type RESULT_TYPE.
3416      Then the expression will be built.
3417      It will be given type FINAL_TYPE if that is nonzero;
3418      otherwise, it will be given type RESULT_TYPE.  */
3419
3420   /* Issue warnings about peculiar, but valid, uses of NULL.  */
3421   if (/* It's reasonable to use pointer values as operands of &&
3422          and ||, so NULL is no exception.  */
3423       !(code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
3424       && (/* If OP0 is NULL and OP1 is not a pointer, or vice versa.  */
3425           (orig_op0 == null_node
3426            && TREE_CODE (TREE_TYPE (op1)) != POINTER_TYPE)
3427           /* Or vice versa.  */
3428           || (orig_op1 == null_node
3429               && TREE_CODE (TREE_TYPE (op0)) != POINTER_TYPE)
3430           /* Or, both are NULL and the operation was not a comparison.  */
3431           || (orig_op0 == null_node && orig_op1 == null_node
3432               && code != EQ_EXPR && code != NE_EXPR)))
3433     /* Some sort of arithmetic operation involving NULL was
3434        performed.  Note that pointer-difference and pointer-addition
3435        have already been handled above, and so we don't end up here in
3436        that case.  */
3437     warning ("NULL used in arithmetic");
3438
3439   if (! converted)
3440     {
3441       if (TREE_TYPE (op0) != result_type)
3442         op0 = cp_convert (result_type, op0);
3443       if (TREE_TYPE (op1) != result_type)
3444         op1 = cp_convert (result_type, op1);
3445
3446       if (op0 == error_mark_node || op1 == error_mark_node)
3447         return error_mark_node;
3448     }
3449
3450   if (build_type == NULL_TREE)
3451     build_type = result_type;
3452
3453   result = build2 (resultcode, build_type, op0, op1);
3454   result = fold_if_not_in_template (result);
3455   if (final_type != 0)
3456     result = cp_convert (final_type, result);
3457   return result;
3458 }
3459 \f
3460 /* Return a tree for the sum or difference (RESULTCODE says which)
3461    of pointer PTROP and integer INTOP.  */
3462
3463 static tree
3464 cp_pointer_int_sum (enum tree_code resultcode, tree ptrop, tree intop)
3465 {
3466   tree res_type = TREE_TYPE (ptrop);
3467
3468   /* pointer_int_sum() uses size_in_bytes() on the TREE_TYPE(res_type)
3469      in certain circumstance (when it's valid to do so).  So we need
3470      to make sure it's complete.  We don't need to check here, if we
3471      can actually complete it at all, as those checks will be done in
3472      pointer_int_sum() anyway.  */
3473   complete_type (TREE_TYPE (res_type));
3474
3475   return pointer_int_sum (resultcode, ptrop,
3476                           fold_if_not_in_template (intop));
3477 }
3478
3479 /* Return a tree for the difference of pointers OP0 and OP1.
3480    The resulting tree has type int.  */
3481
3482 static tree
3483 pointer_diff (tree op0, tree op1, tree ptrtype)
3484 {
3485   tree result;
3486   tree restype = ptrdiff_type_node;
3487   tree target_type = TREE_TYPE (ptrtype);
3488
3489   if (!complete_type_or_else (target_type, NULL_TREE))
3490     return error_mark_node;
3491
3492   if (pedantic || warn_pointer_arith)
3493     {
3494       if (TREE_CODE (target_type) == VOID_TYPE)
3495         pedwarn ("ISO C++ forbids using pointer of type %<void *%> in subtraction");
3496       if (TREE_CODE (target_type) == FUNCTION_TYPE)
3497         pedwarn ("ISO C++ forbids using pointer to a function in subtraction");
3498       if (TREE_CODE (target_type) == METHOD_TYPE)
3499         pedwarn ("ISO C++ forbids using pointer to a method in subtraction");
3500     }
3501
3502   /* First do the subtraction as integers;
3503      then drop through to build the divide operator.  */
3504
3505   op0 = cp_build_binary_op (MINUS_EXPR,
3506                             cp_convert (restype, op0),
3507                             cp_convert (restype, op1));
3508
3509   /* This generates an error if op1 is a pointer to an incomplete type.  */
3510   if (!COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (op1))))
3511     error ("invalid use of a pointer to an incomplete type in pointer arithmetic");
3512
3513   op1 = (TYPE_PTROB_P (ptrtype)
3514          ? size_in_bytes (target_type)
3515          : integer_one_node);
3516
3517   /* Do the division.  */
3518
3519   result = build2 (EXACT_DIV_EXPR, restype, op0, cp_convert (restype, op1));
3520   return fold_if_not_in_template (result);
3521 }
3522 \f
3523 /* Construct and perhaps optimize a tree representation
3524    for a unary operation.  CODE, a tree_code, specifies the operation
3525    and XARG is the operand.  */
3526
3527 tree
3528 build_x_unary_op (enum tree_code code, tree xarg)
3529 {
3530   tree orig_expr = xarg;
3531   tree exp;
3532   int ptrmem = 0;
3533
3534   if (processing_template_decl)
3535     {
3536       if (type_dependent_expression_p (xarg))
3537         return build_min_nt (code, xarg, NULL_TREE);
3538
3539       /* For non-dependent pointer-to-member, the SCOPE_REF will be
3540          processed during template substitution.  Just compute the
3541          right type here and build an ADDR_EXPR around it for
3542          diagnostics.  */
3543       if (code == ADDR_EXPR && TREE_CODE (xarg) == SCOPE_REF)
3544         {
3545           tree type;
3546           if (TREE_TYPE (xarg) == unknown_type_node)
3547             type = unknown_type_node;
3548           else if (TREE_CODE (TREE_TYPE (xarg)) == FUNCTION_TYPE)
3549             type = build_pointer_type (TREE_TYPE (xarg));
3550           else
3551             type = build_ptrmem_type (TREE_OPERAND (xarg, 0),
3552                                       TREE_TYPE (xarg));
3553           return build_min (code, type, xarg, NULL_TREE);
3554         }
3555
3556       xarg = build_non_dependent_expr (xarg);
3557     }
3558
3559   exp = NULL_TREE;
3560
3561   /* [expr.unary.op] says:
3562
3563        The address of an object of incomplete type can be taken.
3564
3565      (And is just the ordinary address operator, not an overloaded
3566      "operator &".)  However, if the type is a template
3567      specialization, we must complete the type at this point so that
3568      an overloaded "operator &" will be available if required.  */
3569   if (code == ADDR_EXPR
3570       && TREE_CODE (xarg) != TEMPLATE_ID_EXPR
3571       && ((CLASS_TYPE_P (TREE_TYPE (xarg))
3572            && !COMPLETE_TYPE_P (complete_type (TREE_TYPE (xarg))))
3573           || (TREE_CODE (xarg) == OFFSET_REF)))
3574     /* Don't look for a function.  */;
3575   else
3576     exp = build_new_op (code, LOOKUP_NORMAL, xarg, NULL_TREE, NULL_TREE,
3577                         /*overloaded_p=*/NULL);
3578   if (!exp && code == ADDR_EXPR)
3579     {
3580       /*  A pointer to member-function can be formed only by saying
3581           &X::mf.  */
3582       if (!flag_ms_extensions && TREE_CODE (TREE_TYPE (xarg)) == METHOD_TYPE
3583           && (TREE_CODE (xarg) != OFFSET_REF || !PTRMEM_OK_P (xarg)))
3584         {
3585           if (TREE_CODE (xarg) != OFFSET_REF)
3586             {
3587               error ("invalid use of %qE to form a pointer-to-member-function."
3588                      "  Use a qualified-id.",
3589                      xarg);
3590               return error_mark_node;
3591             }
3592           else
3593             {
3594               error ("parenthesis around %qE cannot be used to form a"
3595                      " pointer-to-member-function",
3596                      xarg);
3597               PTRMEM_OK_P (xarg) = 1;
3598             }
3599         }
3600
3601       if (TREE_CODE (xarg) == OFFSET_REF)
3602         {
3603           ptrmem = PTRMEM_OK_P (xarg);
3604
3605           if (!ptrmem && !flag_ms_extensions
3606               && TREE_CODE (TREE_TYPE (TREE_OPERAND (xarg, 1))) == METHOD_TYPE)
3607             {
3608               /* A single non-static member, make sure we don't allow a
3609                  pointer-to-member.  */
3610               xarg = build2 (OFFSET_REF, TREE_TYPE (xarg),
3611                              TREE_OPERAND (xarg, 0),
3612                              ovl_cons (TREE_OPERAND (xarg, 1), NULL_TREE));
3613               PTRMEM_OK_P (xarg) = ptrmem;
3614             }
3615         }
3616       else if (TREE_CODE (xarg) == TARGET_EXPR)
3617         warning ("taking address of temporary");
3618       exp = build_unary_op (ADDR_EXPR, xarg, 0);
3619       if (TREE_CODE (exp) == ADDR_EXPR)
3620         PTRMEM_OK_P (exp) = ptrmem;
3621     }
3622
3623   if (processing_template_decl && exp != error_mark_node)
3624     return build_min_non_dep (code, exp, orig_expr,
3625                               /*For {PRE,POST}{INC,DEC}REMENT_EXPR*/NULL_TREE);
3626   return exp;
3627 }
3628
3629 /* Like c_common_truthvalue_conversion, but handle pointer-to-member
3630    constants, where a null value is represented by an INTEGER_CST of
3631    -1.  */
3632
3633 tree
3634 cp_truthvalue_conversion (tree expr)
3635 {
3636   tree type = TREE_TYPE (expr);
3637   if (TYPE_PTRMEM_P (type))
3638     return build_binary_op (NE_EXPR, expr, integer_zero_node, 1);
3639   else
3640     return c_common_truthvalue_conversion (expr);
3641 }
3642
3643 /* Just like cp_truthvalue_conversion, but we want a CLEANUP_POINT_EXPR.  */
3644
3645 tree
3646 condition_conversion (tree expr)
3647 {
3648   tree t;
3649   if (processing_template_decl)
3650     return expr;
3651   t = perform_implicit_conversion (boolean_type_node, expr);
3652   t = fold_build_cleanup_point_expr (boolean_type_node, t);
3653   return t;
3654 }
3655
3656 /* Return an ADDR_EXPR giving the address of T.  This function
3657    attempts no optimizations or simplifications; it is a low-level
3658    primitive.  */
3659
3660 tree
3661 build_address (tree t)
3662 {
3663   tree addr;
3664
3665   if (error_operand_p (t) || !cxx_mark_addressable (t))
3666     return error_mark_node;
3667
3668   addr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (t)), t);
3669
3670   return addr;
3671 }
3672
3673 /* Return a NOP_EXPR converting EXPR to TYPE.  */
3674
3675 tree
3676 build_nop (tree type, tree expr)
3677 {
3678   if (type == error_mark_node || error_operand_p (expr))
3679     return expr;
3680   return build1 (NOP_EXPR, type, expr);
3681 }
3682
3683 /* C++: Must handle pointers to members.
3684
3685    Perhaps type instantiation should be extended to handle conversion
3686    from aggregates to types we don't yet know we want?  (Or are those
3687    cases typically errors which should be reported?)
3688
3689    NOCONVERT nonzero suppresses the default promotions
3690    (such as from short to int).  */
3691
3692 tree
3693 build_unary_op (enum tree_code code, tree xarg, int noconvert)
3694 {
3695   /* No default_conversion here.  It causes trouble for ADDR_EXPR.  */
3696   tree arg = xarg;
3697   tree argtype = 0;
3698   const char *errstring = NULL;
3699   tree val;
3700
3701   if (arg == error_mark_node)
3702     return error_mark_node;
3703
3704   switch (code)
3705     {
3706     /* CONVERT_EXPR stands for unary plus in this context.  */
3707     case CONVERT_EXPR:
3708     case NEGATE_EXPR:
3709       {
3710         int flags = WANT_ARITH | WANT_ENUM;
3711         /* Unary plus (but not unary minus) is allowed on pointers.  */
3712         if (code == CONVERT_EXPR)
3713           flags |= WANT_POINTER;
3714         arg = build_expr_type_conversion (flags, arg, true);
3715         if (!arg)
3716           errstring = (code == NEGATE_EXPR
3717                        ? "wrong type argument to unary minus"
3718                        : "wrong type argument to unary plus");
3719         else
3720           {
3721             if (!noconvert && CP_INTEGRAL_TYPE_P (TREE_TYPE (arg)))
3722               arg = perform_integral_promotions (arg);
3723
3724             /* Make sure the result is not a lvalue: a unary plus or minus
3725                expression is always a rvalue.  */
3726             if (real_lvalue_p (arg))
3727               arg = build1 (NON_LVALUE_EXPR, TREE_TYPE (arg), arg);
3728           }
3729       }
3730       break;
3731
3732     case BIT_NOT_EXPR:
3733       if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
3734         {
3735           code = CONJ_EXPR;
3736           if (!noconvert)
3737             arg = default_conversion (arg);
3738         }
3739       else if (!(arg = build_expr_type_conversion (WANT_INT | WANT_ENUM,
3740                                                    arg, true)))
3741         errstring = "wrong type argument to bit-complement";
3742       else if (!noconvert)
3743         arg = perform_integral_promotions (arg);
3744       break;
3745
3746     case ABS_EXPR:
3747       if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_ENUM, arg, true)))
3748         errstring = "wrong type argument to abs";
3749       else if (!noconvert)
3750         arg = default_conversion (arg);
3751       break;
3752
3753     case CONJ_EXPR:
3754       /* Conjugating a real value is a no-op, but allow it anyway.  */
3755       if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_ENUM, arg, true)))
3756         errstring = "wrong type argument to conjugation";
3757       else if (!noconvert)
3758         arg = default_conversion (arg);
3759       break;
3760
3761     case TRUTH_NOT_EXPR:
3762       arg = perform_implicit_conversion (boolean_type_node, arg);
3763       val = invert_truthvalue (arg);
3764       if (arg != error_mark_node)
3765         return val;
3766       errstring = "in argument to unary !";
3767       break;
3768
3769     case NOP_EXPR:
3770       break;
3771
3772     case REALPART_EXPR:
3773       if (TREE_CODE (arg) == COMPLEX_CST)
3774         return TREE_REALPART (arg);
3775       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
3776         {
3777           arg = build1 (REALPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg);
3778           return fold_if_not_in_template (arg);
3779         }
3780       else
3781         return arg;
3782
3783     case IMAGPART_EXPR:
3784       if (TREE_CODE (arg) == COMPLEX_CST)
3785         return TREE_IMAGPART (arg);
3786       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
3787         {
3788           arg = build1 (IMAGPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg);
3789           return fold_if_not_in_template (arg);
3790         }
3791       else
3792         return cp_convert (TREE_TYPE (arg), integer_zero_node);
3793
3794     case PREINCREMENT_EXPR:
3795     case POSTINCREMENT_EXPR:
3796     case PREDECREMENT_EXPR:
3797     case POSTDECREMENT_EXPR:
3798       /* Handle complex lvalues (when permitted)
3799          by reduction to simpler cases.  */
3800
3801       val = unary_complex_lvalue (code, arg);
3802       if (val != 0)
3803         return val;
3804
3805       /* Increment or decrement the real part of the value,
3806          and don't change the imaginary part.  */
3807       if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
3808         {
3809           tree real, imag;
3810
3811           arg = stabilize_reference (arg);
3812           real = build_unary_op (REALPART_EXPR, arg, 1);
3813           imag = build_unary_op (IMAGPART_EXPR, arg, 1);
3814           return build2 (COMPLEX_EXPR, TREE_TYPE (arg),
3815                          build_unary_op (code, real, 1), imag);
3816         }
3817
3818       /* Report invalid types.  */
3819
3820       if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_POINTER,
3821                                               arg, true)))
3822         {
3823           if (code == PREINCREMENT_EXPR)
3824             errstring ="no pre-increment operator for type";
3825           else if (code == POSTINCREMENT_EXPR)
3826             errstring ="no post-increment operator for type";
3827           else if (code == PREDECREMENT_EXPR)
3828             errstring ="no pre-decrement operator for type";
3829           else
3830             errstring ="no post-decrement operator for type";
3831           break;
3832         }
3833
3834       /* Report something read-only.  */
3835
3836       if (CP_TYPE_CONST_P (TREE_TYPE (arg))
3837           || TREE_READONLY (arg))
3838         readonly_error (arg, ((code == PREINCREMENT_EXPR
3839                                || code == POSTINCREMENT_EXPR)
3840                               ? "increment" : "decrement"),
3841                         0);
3842
3843       {
3844         tree inc;
3845         tree result_type = TREE_TYPE (arg);
3846
3847         arg = get_unwidened (arg, 0);
3848         argtype = TREE_TYPE (arg);
3849
3850         /* ARM $5.2.5 last annotation says this should be forbidden.  */
3851         if (TREE_CODE (argtype) == ENUMERAL_TYPE)
3852           pedwarn ("ISO C++ forbids %sing an enum",
3853                    (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
3854                    ? "increment" : "decrement");
3855
3856         /* Compute the increment.  */
3857
3858         if (TREE_CODE (argtype) == POINTER_TYPE)
3859           {
3860             tree type = complete_type (TREE_TYPE (argtype));
3861
3862             if (!COMPLETE_OR_VOID_TYPE_P (type))
3863               error ("cannot %s a pointer to incomplete type %qT",
3864                      ((code == PREINCREMENT_EXPR
3865                        || code == POSTINCREMENT_EXPR)
3866                       ? "increment" : "decrement"), TREE_TYPE (argtype));
3867             else if ((pedantic || warn_pointer_arith)
3868                      && !TYPE_PTROB_P (argtype))
3869               pedwarn ("ISO C++ forbids %sing a pointer of type %qT",
3870                        ((code == PREINCREMENT_EXPR
3871                          || code == POSTINCREMENT_EXPR)
3872                         ? "increment" : "decrement"), argtype);
3873             inc = cxx_sizeof_nowarn (TREE_TYPE (argtype));
3874           }
3875         else
3876           inc = integer_one_node;
3877
3878         inc = cp_convert (argtype, inc);
3879
3880         /* Handle incrementing a cast-expression.  */
3881
3882         switch (TREE_CODE (arg))
3883           {
3884           case NOP_EXPR:
3885           case CONVERT_EXPR:
3886           case FLOAT_EXPR:
3887           case FIX_TRUNC_EXPR:
3888           case FIX_FLOOR_EXPR:
3889           case FIX_ROUND_EXPR:
3890           case FIX_CEIL_EXPR:
3891             {
3892               tree incremented, modify, value, compound;
3893               if (! lvalue_p (arg) && pedantic)
3894                 pedwarn ("cast to non-reference type used as lvalue");
3895               arg = stabilize_reference (arg);
3896               if (code == PREINCREMENT_EXPR || code == PREDECREMENT_EXPR)
3897                 value = arg;
3898               else
3899                 value = save_expr (arg);
3900               incremented = build2 (((code == PREINCREMENT_EXPR
3901                                       || code == POSTINCREMENT_EXPR)
3902                                      ? PLUS_EXPR : MINUS_EXPR),
3903                                     argtype, value, inc);
3904
3905               modify = build_modify_expr (arg, NOP_EXPR, incremented);
3906               compound = build2 (COMPOUND_EXPR, TREE_TYPE (arg),
3907                                  modify, value);
3908
3909               /* Eliminate warning about unused result of + or -.  */
3910               TREE_NO_WARNING (compound) = 1;
3911               return compound;
3912             }
3913
3914           default:
3915             break;
3916           }
3917
3918         /* Complain about anything else that is not a true lvalue.  */
3919         if (!lvalue_or_else (arg, ((code == PREINCREMENT_EXPR
3920                                     || code == POSTINCREMENT_EXPR)
3921                                    ? lv_increment : lv_decrement)))
3922           return error_mark_node;
3923
3924         /* Forbid using -- on `bool'.  */
3925         if (TREE_TYPE (arg) == boolean_type_node)
3926           {
3927             if (code == POSTDECREMENT_EXPR || code == PREDECREMENT_EXPR)
3928               {
3929                 error ("invalid use of %<--%> on bool variable %qD", arg);
3930                 return error_mark_node;
3931               }
3932             val = boolean_increment (code, arg);
3933           }
3934         else
3935           val = build2 (code, TREE_TYPE (arg), arg, inc);
3936
3937         TREE_SIDE_EFFECTS (val) = 1;
3938         return cp_convert (result_type, val);
3939       }
3940
3941     case ADDR_EXPR:
3942       /* Note that this operation never does default_conversion
3943          regardless of NOCONVERT.  */
3944
3945       argtype = lvalue_type (arg);
3946
3947       if (TREE_CODE (arg) == OFFSET_REF)
3948         goto offset_ref;
3949
3950       if (TREE_CODE (argtype) == REFERENCE_TYPE)
3951         {
3952           tree type = build_pointer_type (TREE_TYPE (argtype));
3953           arg = build1 (CONVERT_EXPR, type, arg);
3954           return arg;
3955         }
3956       else if (pedantic && DECL_MAIN_P (arg))
3957         /* ARM $3.4 */
3958         pedwarn ("ISO C++ forbids taking address of function %<::main%>");
3959
3960       /* Let &* cancel out to simplify resulting code.  */
3961       if (TREE_CODE (arg) == INDIRECT_REF)
3962         {
3963           /* We don't need to have `current_class_ptr' wrapped in a
3964              NON_LVALUE_EXPR node.  */
3965           if (arg == current_class_ref)
3966             return current_class_ptr;
3967
3968           arg = TREE_OPERAND (arg, 0);
3969           if (TREE_CODE (TREE_TYPE (arg)) == REFERENCE_TYPE)
3970             {
3971               tree type = build_pointer_type (TREE_TYPE (TREE_TYPE (arg)));
3972               arg = build1 (CONVERT_EXPR, type, arg);
3973             }
3974           else if (lvalue_p (arg))
3975             /* Don't let this be an lvalue.  */
3976             return non_lvalue (arg);
3977           return arg;
3978         }
3979
3980       /* Uninstantiated types are all functions.  Taking the
3981          address of a function is a no-op, so just return the
3982          argument.  */
3983
3984       gcc_assert (TREE_CODE (arg) != IDENTIFIER_NODE
3985                   || !IDENTIFIER_OPNAME_P (arg));
3986
3987       if (TREE_CODE (arg) == COMPONENT_REF && type_unknown_p (arg)
3988           && !really_overloaded_fn (TREE_OPERAND (arg, 1)))
3989         {
3990           /* They're trying to take the address of a unique non-static
3991              member function.  This is ill-formed (except in MS-land),
3992              but let's try to DTRT.
3993              Note: We only handle unique functions here because we don't
3994              want to complain if there's a static overload; non-unique
3995              cases will be handled by instantiate_type.  But we need to
3996              handle this case here to allow casts on the resulting PMF.
3997              We could defer this in non-MS mode, but it's easier to give
3998              a useful error here.  */
3999
4000           /* Inside constant member functions, the `this' pointer
4001              contains an extra const qualifier.  TYPE_MAIN_VARIANT
4002              is used here to remove this const from the diagnostics
4003              and the created OFFSET_REF.  */
4004           tree base = TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg, 0)));
4005           tree name = DECL_NAME (get_first_fn (TREE_OPERAND (arg, 1)));
4006
4007           if (! flag_ms_extensions)
4008             {
4009               if (current_class_type
4010                   && TREE_OPERAND (arg, 0) == current_class_ref)
4011                 /* An expression like &memfn.  */
4012                 pedwarn ("ISO C++ forbids taking the address of an unqualified"
4013                          " or parenthesized non-static member function to form"
4014                          " a pointer to member function.  Say %<&%T::%D%>",
4015                          base, name);
4016               else
4017                 pedwarn ("ISO C++ forbids taking the address of a bound member"
4018                          " function to form a pointer to member function."
4019                          "  Say %<&%T::%D%>",
4020                          base, name);
4021             }
4022           arg = build_offset_ref (base, name, /*address_p=*/true);
4023         }
4024
4025     offset_ref:
4026       if (type_unknown_p (arg))
4027         return build1 (ADDR_EXPR, unknown_type_node, arg);
4028
4029       /* Handle complex lvalues (when permitted)
4030          by reduction to simpler cases.  */
4031       val = unary_complex_lvalue (code, arg);
4032       if (val != 0)
4033         return val;
4034
4035       switch (TREE_CODE (arg))
4036         {
4037         case NOP_EXPR:
4038         case CONVERT_EXPR:
4039         case FLOAT_EXPR:
4040         case FIX_TRUNC_EXPR:
4041         case FIX_FLOOR_EXPR:
4042         case FIX_ROUND_EXPR:
4043         case FIX_CEIL_EXPR:
4044           if (! lvalue_p (arg) && pedantic)
4045             pedwarn ("ISO C++ forbids taking the address of a cast to a non-lvalue expression");
4046           break;
4047
4048         case OVERLOAD:
4049           arg = OVL_CURRENT (arg);
4050           break;
4051
4052         default:
4053           break;
4054         }
4055
4056       /* Allow the address of a constructor if all the elements
4057          are constant.  */
4058       if (TREE_CODE (arg) == CONSTRUCTOR && TREE_HAS_CONSTRUCTOR (arg)
4059           && TREE_CONSTANT (arg))
4060         ;
4061       /* Anything not already handled and not a true memory reference
4062          is an error.  */
4063       else if (TREE_CODE (argtype) != FUNCTION_TYPE
4064                && TREE_CODE (argtype) != METHOD_TYPE
4065                && !lvalue_or_else (arg, lv_addressof))
4066         return error_mark_node;
4067
4068       if (argtype != error_mark_node)
4069         argtype = build_pointer_type (argtype);
4070
4071       {
4072         tree addr;
4073
4074         if (TREE_CODE (arg) != COMPONENT_REF
4075             /* Inside a template, we are processing a non-dependent
4076                expression so we can just form an ADDR_EXPR with the
4077                correct type.  */
4078             || processing_template_decl)
4079           addr = build_address (arg);
4080         else if (TREE_CODE (TREE_OPERAND (arg, 1)) == BASELINK)
4081           {
4082             tree fn = BASELINK_FUNCTIONS (TREE_OPERAND (arg, 1));
4083
4084             /* We can only get here with a single static member
4085                function.  */
4086             gcc_assert (TREE_CODE (fn) == FUNCTION_DECL
4087                         && DECL_STATIC_FUNCTION_P (fn));
4088             mark_used (fn);
4089             addr = build_address (fn);
4090             if (TREE_SIDE_EFFECTS (TREE_OPERAND (arg, 0)))
4091               /* Do not lose object's side effects.  */
4092               addr = build2 (COMPOUND_EXPR, TREE_TYPE (addr),
4093                              TREE_OPERAND (arg, 0), addr);
4094           }
4095         else if (DECL_C_BIT_FIELD (TREE_OPERAND (arg, 1)))
4096           {
4097             error ("attempt to take address of bit-field structure member %qD",
4098                    TREE_OPERAND (arg, 1));
4099             return error_mark_node;
4100           }
4101         else
4102           {
4103             tree field = TREE_OPERAND (arg, 1);
4104             tree rval = build_unary_op (ADDR_EXPR, TREE_OPERAND (arg, 0), 0);
4105             tree binfo = lookup_base (TREE_TYPE (TREE_TYPE (rval)),
4106                                       decl_type_context (field),
4107                                       ba_check, NULL);
4108
4109             rval = build_base_path (PLUS_EXPR, rval, binfo, 1);
4110
4111             TREE_OPERAND (arg, 0) = build_indirect_ref (rval, NULL);
4112             addr = build_address (arg);
4113           }
4114
4115         if (TREE_CODE (argtype) == POINTER_TYPE
4116             && TREE_CODE (TREE_TYPE (argtype)) == METHOD_TYPE)
4117           {
4118             build_ptrmemfunc_type (argtype);
4119             addr = build_ptrmemfunc (argtype, addr, 0,
4120                                      /*c_cast_p=*/false);
4121           }
4122
4123         return addr;
4124       }
4125
4126     default:
4127       break;
4128     }
4129
4130   if (!errstring)
4131     {
4132       if (argtype == 0)
4133         argtype = TREE_TYPE (arg);
4134       return fold_if_not_in_template (build1 (code, argtype, arg));
4135     }
4136
4137   error ("%s", errstring);
4138   return error_mark_node;
4139 }
4140
4141 /* Apply unary lvalue-demanding operator CODE to the expression ARG
4142    for certain kinds of expressions which are not really lvalues
4143    but which we can accept as lvalues.
4144
4145    If ARG is not a kind of expression we can handle, return
4146    NULL_TREE.  */
4147
4148 tree
4149 unary_complex_lvalue (enum tree_code code, tree arg)
4150 {
4151   /* Inside a template, making these kinds of adjustments is
4152      pointless; we are only concerned with the type of the
4153      expression.  */
4154   if (processing_template_decl)
4155     return NULL_TREE;
4156
4157   /* Handle (a, b) used as an "lvalue".  */
4158   if (TREE_CODE (arg) == COMPOUND_EXPR)
4159     {
4160       tree real_result = build_unary_op (code, TREE_OPERAND (arg, 1), 0);
4161       return build2 (COMPOUND_EXPR, TREE_TYPE (real_result),
4162                      TREE_OPERAND (arg, 0), real_result);
4163     }
4164
4165   /* Handle (a ? b : c) used as an "lvalue".  */
4166   if (TREE_CODE (arg) == COND_EXPR
4167       || TREE_CODE (arg) == MIN_EXPR || TREE_CODE (arg) == MAX_EXPR)
4168     return rationalize_conditional_expr (code, arg);
4169
4170   /* Handle (a = b), (++a), and (--a) used as an "lvalue".  */
4171   if (TREE_CODE (arg) == MODIFY_EXPR
4172       || TREE_CODE (arg) == PREINCREMENT_EXPR
4173       || TREE_CODE (arg) == PREDECREMENT_EXPR)
4174     {
4175       tree lvalue = TREE_OPERAND (arg, 0);
4176       if (TREE_SIDE_EFFECTS (lvalue))
4177         {
4178           lvalue = stabilize_reference (lvalue);
4179           arg = build2 (TREE_CODE (arg), TREE_TYPE (arg),
4180                         lvalue, TREE_OPERAND (arg, 1));
4181         }
4182       return unary_complex_lvalue
4183         (code, build2 (COMPOUND_EXPR, TREE_TYPE (lvalue), arg, lvalue));
4184     }
4185
4186   if (code != ADDR_EXPR)
4187     return 0;
4188
4189   /* Handle (a = b) used as an "lvalue" for `&'.  */
4190   if (TREE_CODE (arg) == MODIFY_EXPR
4191       || TREE_CODE (arg) == INIT_EXPR)
4192     {
4193       tree real_result = build_unary_op (code, TREE_OPERAND (arg, 0), 0);
4194       arg = build2 (COMPOUND_EXPR, TREE_TYPE (real_result),
4195                     arg, real_result);
4196       TREE_NO_WARNING (arg) = 1;
4197       return arg;
4198     }
4199
4200   if (TREE_CODE (TREE_TYPE (arg)) == FUNCTION_TYPE
4201       || TREE_CODE (TREE_TYPE (arg)) == METHOD_TYPE
4202       || TREE_CODE (arg) == OFFSET_REF)
4203     {
4204       tree t;
4205
4206       gcc_assert (TREE_CODE (arg) != SCOPE_REF);
4207
4208       if (TREE_CODE (arg) != OFFSET_REF)
4209         return 0;
4210
4211       t = TREE_OPERAND (arg, 1);
4212
4213       /* Check all this code for right semantics.  */
4214       if (TREE_CODE (t) == FUNCTION_DECL)
4215         {
4216           if (DECL_DESTRUCTOR_P (t))
4217             error ("taking address of destructor");
4218           return build_unary_op (ADDR_EXPR, t, 0);
4219         }
4220       if (TREE_CODE (t) == VAR_DECL)
4221         return build_unary_op (ADDR_EXPR, t, 0);
4222       else
4223         {
4224           tree type;
4225
4226           if (TREE_OPERAND (arg, 0)
4227               && ! is_dummy_object (TREE_OPERAND (arg, 0))
4228               && TREE_CODE (t) != FIELD_DECL)
4229             {
4230               error ("taking address of bound pointer-to-member expression");
4231               return error_mark_node;
4232             }
4233           if (!PTRMEM_OK_P (arg))
4234             return build_unary_op (code, arg, 0);
4235
4236           if (TREE_CODE (TREE_TYPE (t)) == REFERENCE_TYPE)
4237             {
4238               error ("cannot create pointer to reference member %qD", t);
4239               return error_mark_node;
4240             }
4241
4242           type = build_ptrmem_type (context_for_name_lookup (t),
4243                                     TREE_TYPE (t));
4244           t = make_ptrmem_cst (type, TREE_OPERAND (arg, 1));
4245           return t;
4246         }
4247     }
4248
4249
4250   /* We permit compiler to make function calls returning
4251      objects of aggregate type look like lvalues.  */
4252   {
4253     tree targ = arg;
4254
4255     if (TREE_CODE (targ) == SAVE_EXPR)
4256       targ = TREE_OPERAND (targ, 0);
4257
4258     if (TREE_CODE (targ) == CALL_EXPR && IS_AGGR_TYPE (TREE_TYPE (targ)))
4259       {
4260         if (TREE_CODE (arg) == SAVE_EXPR)
4261           targ = arg;
4262         else
4263           targ = build_cplus_new (TREE_TYPE (arg), arg);
4264         return build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (arg)), targ);
4265       }
4266
4267     if (TREE_CODE (arg) == SAVE_EXPR && TREE_CODE (targ) == INDIRECT_REF)
4268       return build3 (SAVE_EXPR, build_pointer_type (TREE_TYPE (arg)),
4269                      TREE_OPERAND (targ, 0), current_function_decl, NULL);
4270   }
4271
4272   /* Don't let anything else be handled specially.  */
4273   return 0;
4274 }
4275 \f
4276 /* Mark EXP saying that we need to be able to take the
4277    address of it; it should not be allocated in a register.
4278    Value is true if successful.
4279
4280    C++: we do not allow `current_class_ptr' to be addressable.  */
4281
4282 bool
4283 cxx_mark_addressable (tree exp)
4284 {
4285   tree x = exp;
4286
4287   while (1)
4288     switch (TREE_CODE (x))
4289       {
4290       case ADDR_EXPR:
4291       case COMPONENT_REF:
4292       case ARRAY_REF:
4293       case REALPART_EXPR:
4294       case IMAGPART_EXPR:
4295         x = TREE_OPERAND (x, 0);
4296         break;
4297
4298       case PARM_DECL:
4299         if (x == current_class_ptr)
4300           {
4301             error ("cannot take the address of %<this%>, which is an rvalue expression");
4302             TREE_ADDRESSABLE (x) = 1; /* so compiler doesn't die later.  */
4303             return true;
4304           }
4305         /* Fall through.  */
4306
4307       case VAR_DECL:
4308         /* Caller should not be trying to mark initialized
4309            constant fields addressable.  */
4310         gcc_assert (DECL_LANG_SPECIFIC (x) == 0
4311                     || DECL_IN_AGGR_P (x) == 0
4312                     || TREE_STATIC (x)
4313                     || DECL_EXTERNAL (x));
4314         /* Fall through.  */
4315
4316       case CONST_DECL:
4317       case RESULT_DECL:
4318         if (DECL_REGISTER (x) && !TREE_ADDRESSABLE (x)
4319             && !DECL_ARTIFICIAL (x))
4320           {
4321             if (DECL_HARD_REGISTER (x) != 0)
4322               {
4323                 error
4324                   ("address of explicit register variable %qD requested", x);
4325                 return false;
4326               }
4327             else if (extra_warnings)
4328               warning
4329                 ("address requested for %qD, which is declared %<register%>", x);
4330           }
4331         TREE_ADDRESSABLE (x) = 1;
4332         return true;
4333
4334       case FUNCTION_DECL:
4335         TREE_ADDRESSABLE (x) = 1;
4336         return true;
4337
4338       case CONSTRUCTOR:
4339         TREE_ADDRESSABLE (x) = 1;
4340         return true;
4341
4342       case TARGET_EXPR:
4343         TREE_ADDRESSABLE (x) = 1;
4344         cxx_mark_addressable (TREE_OPERAND (x, 0));
4345         return true;
4346
4347       default:
4348         return true;
4349     }
4350 }
4351 \f
4352 /* Build and return a conditional expression IFEXP ? OP1 : OP2.  */
4353
4354 tree
4355 build_x_conditional_expr (tree ifexp, tree op1, tree op2)
4356 {
4357   tree orig_ifexp = ifexp;
4358   tree orig_op1 = op1;
4359   tree orig_op2 = op2;
4360   tree expr;
4361
4362   if (processing_template_decl)
4363     {
4364       /* The standard says that the expression is type-dependent if
4365          IFEXP is type-dependent, even though the eventual type of the
4366          expression doesn't dependent on IFEXP.  */
4367       if (type_dependent_expression_p (ifexp)
4368           /* As a GNU extension, the middle operand may be omitted.  */
4369           || (op1 && type_dependent_expression_p (op1))
4370           || type_dependent_expression_p (op2))
4371         return build_min_nt (COND_EXPR, ifexp, op1, op2);
4372       ifexp = build_non_dependent_expr (ifexp);
4373       if (op1)
4374         op1 = build_non_dependent_expr (op1);
4375       op2 = build_non_dependent_expr (op2);
4376     }
4377
4378   expr = build_conditional_expr (ifexp, op1, op2);
4379   if (processing_template_decl && expr != error_mark_node)
4380     return build_min_non_dep (COND_EXPR, expr,
4381                               orig_ifexp, orig_op1, orig_op2);
4382   return expr;
4383 }
4384 \f
4385 /* Given a list of expressions, return a compound expression
4386    that performs them all and returns the value of the last of them.  */
4387
4388 tree build_x_compound_expr_from_list (tree list, const char *msg)
4389 {
4390   tree expr = TREE_VALUE (list);
4391
4392   if (TREE_CHAIN (list))
4393     {
4394       if (msg)
4395         pedwarn ("%s expression list treated as compound expression", msg);
4396
4397       for (list = TREE_CHAIN (list); list; list = TREE_CHAIN (list))
4398         expr = build_x_compound_expr (expr, TREE_VALUE (list));
4399     }
4400
4401   return expr;
4402 }
4403
4404 /* Handle overloading of the ',' operator when needed.  */
4405
4406 tree
4407 build_x_compound_expr (tree op1, tree op2)
4408 {
4409   tree result;
4410   tree orig_op1 = op1;
4411   tree orig_op2 = op2;
4412
4413   if (processing_template_decl)
4414     {
4415       if (type_dependent_expression_p (op1)
4416           || type_dependent_expression_p (op2))
4417         return build_min_nt (COMPOUND_EXPR, op1, op2);
4418       op1 = build_non_dependent_expr (op1);
4419       op2 = build_non_dependent_expr (op2);
4420     }
4421
4422   result = build_new_op (COMPOUND_EXPR, LOOKUP_NORMAL, op1, op2, NULL_TREE,
4423                          /*overloaded_p=*/NULL);
4424   if (!result)
4425     result = build_compound_expr (op1, op2);
4426
4427   if (processing_template_decl && result != error_mark_node)
4428     return build_min_non_dep (COMPOUND_EXPR, result, orig_op1, orig_op2);
4429
4430   return result;
4431 }
4432
4433 /* Build a compound expression.  */
4434
4435 tree
4436 build_compound_expr (tree lhs, tree rhs)
4437 {
4438   lhs = convert_to_void (lhs, "left-hand operand of comma");
4439
4440   if (lhs == error_mark_node || rhs == error_mark_node)
4441     return error_mark_node;
4442
4443   if (TREE_CODE (rhs) == TARGET_EXPR)
4444     {
4445       /* If the rhs is a TARGET_EXPR, then build the compound
4446          expression inside the target_expr's initializer. This
4447          helps the compiler to eliminate unnecessary temporaries.  */
4448       tree init = TREE_OPERAND (rhs, 1);
4449
4450       init = build2 (COMPOUND_EXPR, TREE_TYPE (init), lhs, init);
4451       TREE_OPERAND (rhs, 1) = init;
4452
4453       return rhs;
4454     }
4455
4456   return build2 (COMPOUND_EXPR, TREE_TYPE (rhs), lhs, rhs);
4457 }
4458
4459 /* Issue a diagnostic message if casting from SRC_TYPE to DEST_TYPE
4460    casts away constness.  DIAG_FN gives the function to call if we
4461    need to issue a diagnostic; if it is NULL, no diagnostic will be
4462    issued.  DESCRIPTION explains what operation is taking place.  */
4463
4464 static void
4465 check_for_casting_away_constness (tree src_type, tree dest_type,
4466                                   void (*diag_fn)(const char *, ...),
4467                                   const char *description)
4468 {
4469   if (diag_fn && casts_away_constness (src_type, dest_type))
4470     error ("%s from type %qT to type %qT casts away constness",
4471            description, src_type, dest_type);
4472 }
4473
4474 /* Convert EXPR (an expression with pointer-to-member type) to TYPE
4475    (another pointer-to-member type in the same hierarchy) and return
4476    the converted expression.  If ALLOW_INVERSE_P is permitted, a
4477    pointer-to-derived may be converted to pointer-to-base; otherwise,
4478    only the other direction is permitted.  If C_CAST_P is true, this
4479    conversion is taking place as part of a C-style cast.  */
4480
4481 tree
4482 convert_ptrmem (tree type, tree expr, bool allow_inverse_p,
4483                 bool c_cast_p)
4484 {
4485   if (TYPE_PTRMEM_P (type))
4486     {
4487       tree delta;
4488
4489       if (TREE_CODE (expr) == PTRMEM_CST)
4490         expr = cplus_expand_constant (expr);
4491       delta = get_delta_difference (TYPE_PTRMEM_CLASS_TYPE (TREE_TYPE (expr)),
4492                                     TYPE_PTRMEM_CLASS_TYPE (type),
4493                                     allow_inverse_p,
4494                                     c_cast_p);
4495       if (!integer_zerop (delta))
4496         expr = cp_build_binary_op (PLUS_EXPR,
4497                                    build_nop (ptrdiff_type_node, expr),
4498                                    delta);
4499       return build_nop (type, expr);
4500     }
4501   else
4502     return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr,
4503                              allow_inverse_p, c_cast_p);
4504 }
4505
4506 /* Perform a static_cast from EXPR to TYPE.  When C_CAST_P is true,
4507    this static_cast is being attempted as one of the possible casts
4508    allowed by a C-style cast.  (In that case, accessibility of base
4509    classes is not considered, and it is OK to cast away
4510    constness.)  Return the result of the cast.  *VALID_P is set to
4511    indicate whether or not the cast was valid.  */
4512
4513 static tree
4514 build_static_cast_1 (tree type, tree expr, bool c_cast_p,
4515                      bool *valid_p)
4516 {
4517   tree intype;
4518   tree result;
4519   tree orig;
4520   void (*diag_fn)(const char*, ...);
4521   const char *desc;
4522
4523   /* Assume the cast is valid.  */
4524   *valid_p = true;
4525
4526   intype = TREE_TYPE (expr);
4527
4528   /* Determine what to do when casting away constness.  */
4529   if (c_cast_p)
4530     {
4531       /* C-style casts are allowed to cast away constness.  With
4532          WARN_CAST_QUAL, we still want to issue a warning.  */
4533       diag_fn = warn_cast_qual ? warning : NULL;
4534       desc = "cast";
4535     }
4536   else
4537     {
4538       /* A static_cast may not cast away constness.  */
4539       diag_fn = error;
4540       desc = "static_cast";
4541     }
4542
4543   /* [expr.static.cast]
4544
4545      An lvalue of type "cv1 B", where B is a class type, can be cast
4546      to type "reference to cv2 D", where D is a class derived (clause
4547      _class.derived_) from B, if a valid standard conversion from
4548      "pointer to D" to "pointer to B" exists (_conv.ptr_), cv2 is the
4549      same cv-qualification as, or greater cv-qualification than, cv1,
4550      and B is not a virtual base class of D.  */
4551   /* We check this case before checking the validity of "TYPE t =
4552      EXPR;" below because for this case:
4553
4554        struct B {};
4555        struct D : public B { D(const B&); };
4556        extern B& b;
4557        void f() { static_cast<const D&>(b); }
4558
4559      we want to avoid constructing a new D.  The standard is not
4560      completely clear about this issue, but our interpretation is
4561      consistent with other compilers.  */
4562   if (TREE_CODE (type) == REFERENCE_TYPE
4563       && CLASS_TYPE_P (TREE_TYPE (type))
4564       && CLASS_TYPE_P (intype)
4565       && real_lvalue_p (expr)
4566       && DERIVED_FROM_P (intype, TREE_TYPE (type))
4567       && can_convert (build_pointer_type (TYPE_MAIN_VARIANT (intype)),
4568                       build_pointer_type (TYPE_MAIN_VARIANT
4569                                           (TREE_TYPE (type))))
4570       && (c_cast_p
4571           || at_least_as_qualified_p (TREE_TYPE (type), intype)))
4572     {
4573       tree base;
4574
4575       /* There is a standard conversion from "D*" to "B*" even if "B"
4576          is ambiguous or inaccessible.  If this is really a
4577          static_cast, then we check both for inaccessibility and
4578          ambiguity.  However, if this is a static_cast being performed
4579          because the user wrote a C-style cast, then accessibility is
4580          not considered.  */
4581       base = lookup_base (TREE_TYPE (type), intype,
4582                           c_cast_p ? ba_unique : ba_check,
4583                           NULL);
4584
4585       /* Convert from "B*" to "D*".  This function will check that "B"
4586          is not a virtual base of "D".  */
4587       expr = build_base_path (MINUS_EXPR, build_address (expr),
4588                               base, /*nonnull=*/false);
4589       /* Convert the pointer to a reference -- but then remember that
4590          there are no expressions with reference type in C++.  */
4591       return convert_from_reference (build_nop (type, expr));
4592     }
4593
4594   orig = expr;
4595
4596   /* [expr.static.cast]
4597
4598      An expression e can be explicitly converted to a type T using a
4599      static_cast of the form static_cast<T>(e) if the declaration T
4600      t(e);" is well-formed, for some invented temporary variable
4601      t.  */
4602   result = perform_direct_initialization_if_possible (type, expr,
4603                                                       c_cast_p);
4604   if (result)
4605     {
4606       result = convert_from_reference (result);
4607
4608       /* Ignore any integer overflow caused by the cast.  */
4609       if (TREE_CODE (result) == INTEGER_CST
4610           && CONSTANT_CLASS_P (orig))
4611         {
4612           TREE_OVERFLOW (result) = TREE_OVERFLOW (orig);
4613           TREE_CONSTANT_OVERFLOW (result)
4614             = TREE_CONSTANT_OVERFLOW (orig);
4615         }
4616       /* [expr.static.cast]
4617
4618          If T is a reference type, the result is an lvalue; otherwise,
4619          the result is an rvalue.  */
4620       if (TREE_CODE (type) != REFERENCE_TYPE
4621           && real_lvalue_p (result))
4622         result = build1 (NON_LVALUE_EXPR, TREE_TYPE (result), result);
4623       return result;
4624     }
4625
4626   /* [expr.static.cast]
4627
4628      Any expression can be explicitly converted to type cv void.  */
4629   if (TREE_CODE (type) == VOID_TYPE)
4630     return convert_to_void (expr, /*implicit=*/NULL);
4631
4632   /* [expr.static.cast]
4633
4634      The inverse of any standard conversion sequence (clause _conv_),
4635      other than the lvalue-to-rvalue (_conv.lval_), array-to-pointer
4636      (_conv.array_), function-to-pointer (_conv.func_), and boolean
4637      (_conv.bool_) conversions, can be performed explicitly using
4638      static_cast subject to the restriction that the explicit
4639      conversion does not cast away constness (_expr.const.cast_), and
4640      the following additional rules for specific cases:  */
4641   /* For reference, the conversions not excluded are: integral
4642      promotions, floating point promotion, integral conversions,
4643      floating point conversions, floating-integral conversions,
4644      pointer conversions, and pointer to member conversions.  */
4645   if ((ARITHMETIC_TYPE_P (type) && ARITHMETIC_TYPE_P (intype))
4646       /* DR 128
4647
4648          A value of integral _or enumeration_ type can be explicitly
4649          converted to an enumeration type.  */
4650       || (INTEGRAL_OR_ENUMERATION_TYPE_P (type)
4651           && INTEGRAL_OR_ENUMERATION_TYPE_P (intype)))
4652     {
4653       expr = ocp_convert (type, expr, CONV_C_CAST, LOOKUP_NORMAL);
4654
4655       /* Ignore any integer overflow caused by the cast.  */
4656       if (TREE_CODE (expr) == INTEGER_CST
4657           && CONSTANT_CLASS_P (orig))
4658         {
4659           TREE_OVERFLOW (expr) = TREE_OVERFLOW (orig);
4660           TREE_CONSTANT_OVERFLOW (expr) = TREE_CONSTANT_OVERFLOW (orig);
4661         }
4662       return expr;
4663     }
4664
4665   if (TYPE_PTR_P (type) && TYPE_PTR_P (intype)
4666       && CLASS_TYPE_P (TREE_TYPE (type))
4667       && CLASS_TYPE_P (TREE_TYPE (intype))
4668       && can_convert (build_pointer_type (TYPE_MAIN_VARIANT
4669                                           (TREE_TYPE (intype))),
4670                       build_pointer_type (TYPE_MAIN_VARIANT
4671                                           (TREE_TYPE (type)))))
4672     {
4673       tree base;
4674
4675       if (!c_cast_p)
4676         check_for_casting_away_constness (intype, type, diag_fn, desc);
4677       base = lookup_base (TREE_TYPE (type), TREE_TYPE (intype),
4678                           c_cast_p ? ba_unique : ba_check,
4679                           NULL);
4680       return build_base_path (MINUS_EXPR, expr, base, /*nonnull=*/false);
4681     }
4682
4683   if ((TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
4684       || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
4685     {
4686       tree c1;
4687       tree c2;
4688       tree t1;
4689       tree t2;
4690
4691       c1 = TYPE_PTRMEM_CLASS_TYPE (intype);
4692       c2 = TYPE_PTRMEM_CLASS_TYPE (type);
4693
4694       if (TYPE_PTRMEM_P (type))
4695         {
4696           t1 = (build_ptrmem_type
4697                 (c1,
4698                  TYPE_MAIN_VARIANT (TYPE_PTRMEM_POINTED_TO_TYPE (intype))));
4699           t2 = (build_ptrmem_type
4700                 (c2,
4701                  TYPE_MAIN_VARIANT (TYPE_PTRMEM_POINTED_TO_TYPE (type))));
4702         }
4703       else
4704         {
4705           t1 = intype;
4706           t2 = type;
4707         }
4708       if (can_convert (t1, t2))
4709         {
4710           if (!c_cast_p)
4711             check_for_casting_away_constness (intype, type, diag_fn,
4712                                               desc);
4713           return convert_ptrmem (type, expr, /*allow_inverse_p=*/1,
4714                                  c_cast_p);
4715         }
4716     }
4717
4718   /* [expr.static.cast]
4719
4720      An rvalue of type "pointer to cv void" can be explicitly
4721      converted to a pointer to object type.  A value of type pointer
4722      to object converted to "pointer to cv void" and back to the
4723      original pointer type will have its original value.  */
4724   if (TREE_CODE (intype) == POINTER_TYPE
4725       && VOID_TYPE_P (TREE_TYPE (intype))
4726       && TYPE_PTROB_P (type))
4727     {
4728       if (!c_cast_p)
4729         check_for_casting_away_constness (intype, type, diag_fn, desc);
4730       return build_nop (type, expr);
4731     }
4732
4733   *valid_p = false;
4734   return error_mark_node;
4735 }
4736
4737 /* Return an expression representing static_cast<TYPE>(EXPR).  */
4738
4739 tree
4740 build_static_cast (tree type, tree expr)
4741 {
4742   tree result;
4743   bool valid_p;
4744
4745   if (type == error_mark_node || expr == error_mark_node)
4746     return error_mark_node;
4747
4748   if (processing_template_decl)
4749     {
4750       expr = build_min (STATIC_CAST_EXPR, type, expr);
4751       /* We don't know if it will or will not have side effects.  */
4752       TREE_SIDE_EFFECTS (expr) = 1;
4753       return convert_from_reference (expr);
4754     }
4755
4756   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
4757      Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
4758   if (TREE_CODE (type) != REFERENCE_TYPE
4759       && TREE_CODE (expr) == NOP_EXPR
4760       && TREE_TYPE (expr) == TREE_TYPE (TREE_OPERAND (expr, 0)))
4761     expr = TREE_OPERAND (expr, 0);
4762
4763   result = build_static_cast_1 (type, expr, /*c_cast_p=*/false, &valid_p);
4764   if (valid_p)
4765     return result;
4766
4767   error ("invalid static_cast from type %qT to type %qT",
4768          TREE_TYPE (expr), type);
4769   return error_mark_node;
4770 }
4771
4772 /* EXPR is an expression with member function or pointer-to-member
4773    function type.  TYPE is a pointer type.  Converting EXPR to TYPE is
4774    not permitted by ISO C++, but we accept it in some modes.  If we
4775    are not in one of those modes, issue a diagnostic.  Return the
4776    converted expression.  */
4777
4778 tree
4779 convert_member_func_to_ptr (tree type, tree expr)
4780 {
4781   tree intype;
4782   tree decl;
4783
4784   intype = TREE_TYPE (expr);
4785   gcc_assert (TYPE_PTRMEMFUNC_P (intype)
4786               || TREE_CODE (intype) == METHOD_TYPE);
4787
4788   if (pedantic || warn_pmf2ptr)
4789     pedwarn ("converting from %qT to %qT", intype, type);
4790
4791   if (TREE_CODE (intype) == METHOD_TYPE)
4792     expr = build_addr_func (expr);
4793   else if (TREE_CODE (expr) == PTRMEM_CST)
4794     expr = build_address (PTRMEM_CST_MEMBER (expr));
4795   else
4796     {
4797       decl = maybe_dummy_object (TYPE_PTRMEM_CLASS_TYPE (intype), 0);
4798       decl = build_address (decl);
4799       expr = get_member_function_from_ptrfunc (&decl, expr);
4800     }
4801
4802   return build_nop (type, expr);
4803 }
4804
4805 /* Return a representation for a reinterpret_cast from EXPR to TYPE.
4806    If C_CAST_P is true, this reinterpret cast is being done as part of
4807    a C-style cast.  If VALID_P is non-NULL, *VALID_P is set to
4808    indicate whether or not reinterpret_cast was valid.  */
4809
4810 static tree
4811 build_reinterpret_cast_1 (tree type, tree expr, bool c_cast_p,
4812                           bool *valid_p)
4813 {
4814   tree intype;
4815
4816   /* Assume the cast is invalid.  */
4817   if (valid_p)
4818     *valid_p = true;
4819
4820   if (type == error_mark_node || error_operand_p (expr))
4821     return error_mark_node;
4822
4823   intype = TREE_TYPE (expr);
4824
4825   /* [expr.reinterpret.cast]
4826      An lvalue expression of type T1 can be cast to the type
4827      "reference to T2" if an expression of type "pointer to T1" can be
4828      explicitly converted to the type "pointer to T2" using a
4829      reinterpret_cast.  */
4830   if (TREE_CODE (type) == REFERENCE_TYPE)
4831     {
4832       if (! real_lvalue_p (expr))
4833         {
4834           error ("invalid cast of an rvalue expression of type "
4835                  "%qT to type %qT",
4836                  intype, type);
4837           return error_mark_node;
4838         }
4839
4840       /* Warn about a reinterpret_cast from "A*" to "B&" if "A" and
4841          "B" are related class types; the reinterpret_cast does not
4842          adjust the pointer.  */
4843       if (TYPE_PTR_P (intype)
4844           && (comptypes (TREE_TYPE (intype), TREE_TYPE (type),
4845                          COMPARE_BASE | COMPARE_DERIVED)))
4846         warning ("casting %qT to %qT does not dereference pointer",
4847                  intype, type);
4848
4849       expr = build_unary_op (ADDR_EXPR, expr, 0);
4850       if (expr != error_mark_node)
4851         expr = build_reinterpret_cast_1
4852           (build_pointer_type (TREE_TYPE (type)), expr, c_cast_p,
4853            valid_p);
4854       if (expr != error_mark_node)
4855         expr = build_indirect_ref (expr, 0);
4856       return expr;
4857     }
4858
4859   /* As a G++ extension, we consider conversions from member
4860      functions, and pointers to member functions to
4861      pointer-to-function and pointer-to-void types.  If
4862      -Wno-pmf-conversions has not been specified,
4863      convert_member_func_to_ptr will issue an error message.  */
4864   if ((TYPE_PTRMEMFUNC_P (intype)
4865        || TREE_CODE (intype) == METHOD_TYPE)
4866       && TYPE_PTR_P (type)
4867       && (TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE
4868           || VOID_TYPE_P (TREE_TYPE (type))))
4869     return convert_member_func_to_ptr (type, expr);
4870
4871   /* If the cast is not to a reference type, the lvalue-to-rvalue,
4872      array-to-pointer, and function-to-pointer conversions are
4873      performed.  */
4874   expr = decay_conversion (expr);
4875
4876   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
4877      Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
4878   if (TREE_CODE (expr) == NOP_EXPR
4879       && TREE_TYPE (expr) == TREE_TYPE (TREE_OPERAND (expr, 0)))
4880     expr = TREE_OPERAND (expr, 0);
4881
4882   if (error_operand_p (expr))
4883     return error_mark_node;
4884
4885   intype = TREE_TYPE (expr);
4886
4887   /* [expr.reinterpret.cast]
4888      A pointer can be converted to any integral type large enough to
4889      hold it.  */
4890   if (CP_INTEGRAL_TYPE_P (type) && TYPE_PTR_P (intype))
4891     {
4892       if (TYPE_PRECISION (type) < TYPE_PRECISION (intype))
4893         pedwarn ("cast from %qT to %qT loses precision",
4894                  intype, type);
4895     }
4896   /* [expr.reinterpret.cast]
4897      A value of integral or enumeration type can be explicitly
4898      converted to a pointer.  */
4899   else if (TYPE_PTR_P (type) && INTEGRAL_OR_ENUMERATION_TYPE_P (intype))
4900     /* OK */
4901     ;
4902   else if ((TYPE_PTRFN_P (type) && TYPE_PTRFN_P (intype))
4903            || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
4904     return fold_if_not_in_template (build_nop (type, expr));
4905   else if ((TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
4906            || (TYPE_PTROBV_P (type) && TYPE_PTROBV_P (intype)))
4907     {
4908       if (!c_cast_p)
4909         check_for_casting_away_constness (intype, type, error,
4910                                           "reinterpret_cast");
4911       /* Warn about possible alignment problems.  */
4912       if (STRICT_ALIGNMENT && warn_cast_align
4913           && !VOID_TYPE_P (type)
4914           && TREE_CODE (TREE_TYPE (intype)) != FUNCTION_TYPE
4915           && COMPLETE_TYPE_P (TREE_TYPE (type))
4916           && COMPLETE_TYPE_P (TREE_TYPE (intype))
4917           && TYPE_ALIGN (TREE_TYPE (type)) > TYPE_ALIGN (TREE_TYPE (intype)))
4918         warning ("cast from %qT to %qT increases required alignment of "
4919                  "target type",
4920                  intype, type);
4921
4922       return fold_if_not_in_template (build_nop (type, expr));
4923     }
4924   else if ((TYPE_PTRFN_P (type) && TYPE_PTROBV_P (intype))
4925            || (TYPE_PTRFN_P (intype) && TYPE_PTROBV_P (type)))
4926     {
4927       if (pedantic)
4928         /* Only issue a warning, as we have always supported this
4929            where possible, and it is necessary in some cases.  DR 195
4930            addresses this issue, but as of 2004/10/26 is still in
4931            drafting.  */
4932         warning ("ISO C++ forbids casting between pointer-to-function and pointer-to-object");
4933       return fold_if_not_in_template (build_nop (type, expr));
4934     }
4935   else if (TREE_CODE (type) == VECTOR_TYPE)
4936     return fold_if_not_in_template (convert_to_vector (type, expr));
4937   else if (TREE_CODE (intype) == VECTOR_TYPE)
4938     return fold_if_not_in_template (convert_to_integer (type, expr));
4939   else
4940     {
4941       if (valid_p)
4942         *valid_p = false;
4943       error ("invalid cast from type %qT to type %qT", intype, type);
4944       return error_mark_node;
4945     }
4946
4947   return cp_convert (type, expr);
4948 }
4949
4950 tree
4951 build_reinterpret_cast (tree type, tree expr)
4952 {
4953   if (type == error_mark_node || expr == error_mark_node)
4954     return error_mark_node;
4955
4956   if (processing_template_decl)
4957     {
4958       tree t = build_min (REINTERPRET_CAST_EXPR, type, expr);
4959
4960       if (!TREE_SIDE_EFFECTS (t)
4961           && type_dependent_expression_p (expr))
4962         /* There might turn out to be side effects inside expr.  */
4963         TREE_SIDE_EFFECTS (t) = 1;
4964       return convert_from_reference (t);
4965     }
4966
4967   return build_reinterpret_cast_1 (type, expr, /*c_cast_p=*/false,
4968                                    /*valid_p=*/NULL);
4969 }
4970
4971 /* Perform a const_cast from EXPR to TYPE.  If the cast is valid,
4972    return an appropriate expression.  Otherwise, return
4973    error_mark_node.  If the cast is not valid, and COMPLAIN is true,
4974    then a diagnostic will be issued.  If VALID_P is non-NULL, its
4975    value upon return will indicate whether or not the conversion
4976    succeeded.  */
4977
4978 static tree
4979 build_const_cast_1 (tree dst_type, tree expr, bool complain,
4980                     bool *valid_p)
4981 {
4982   tree src_type;
4983   tree reference_type;
4984
4985   /* Callers are responsible for handling error_mark_node as a
4986      destination type.  */
4987   gcc_assert (dst_type != error_mark_node);
4988   /* In a template, callers should be building syntactic
4989      representations of casts, not using this machinery.  */
4990   gcc_assert (!processing_template_decl);
4991
4992   /* Assume the conversion is invalid.  */
4993   if (valid_p)
4994     *valid_p = false;
4995
4996   if (!POINTER_TYPE_P (dst_type) && !TYPE_PTRMEM_P (dst_type))
4997     {
4998       if (complain)
4999         error ("invalid use of const_cast with type %qT, "
5000                "which is not a pointer, "
5001                "reference, nor a pointer-to-data-member type", dst_type);
5002       return error_mark_node;
5003     }
5004
5005   if (TREE_CODE (TREE_TYPE (dst_type)) == FUNCTION_TYPE)
5006     {
5007       if (complain)
5008         error ("invalid use of const_cast with type %qT, which is a pointer "
5009                "or reference to a function type", dst_type);
5010       return error_mark_node;
5011     }
5012
5013   src_type = TREE_TYPE (expr);
5014   /* Expressions do not really have reference types.  */
5015   if (TREE_CODE (src_type) == REFERENCE_TYPE)
5016     src_type = TREE_TYPE (src_type);
5017
5018   /* [expr.const.cast]
5019
5020      An lvalue of type T1 can be explicitly converted to an lvalue of
5021      type T2 using the cast const_cast<T2&> (where T1 and T2 are object
5022      types) if a pointer to T1 can be explicitly converted to the type
5023      pointer to T2 using a const_cast.  */
5024   if (TREE_CODE (dst_type) == REFERENCE_TYPE)
5025     {
5026       reference_type = dst_type;
5027       if (! real_lvalue_p (expr))
5028         {
5029           if (complain)
5030             error ("invalid const_cast of an rvalue of type %qT to type %qT",
5031                    src_type, dst_type);
5032           return error_mark_node;
5033         }
5034       dst_type = build_pointer_type (TREE_TYPE (dst_type));
5035       src_type = build_pointer_type (src_type);
5036     }
5037   else
5038     {
5039       reference_type = NULL_TREE;
5040       /* If the destination type is not a reference type, the
5041          lvalue-to-rvalue, array-to-pointer, and function-to-pointer
5042          conversions are performed.  */
5043       src_type = type_decays_to (src_type);
5044       if (src_type == error_mark_node)
5045         return error_mark_node;
5046     }
5047
5048   if ((TYPE_PTR_P (src_type) || TYPE_PTRMEM_P (src_type))
5049       && comp_ptr_ttypes_const (dst_type, src_type))
5050     {
5051       if (valid_p)
5052         *valid_p = true;
5053       if (reference_type)
5054         {
5055           expr = build_unary_op (ADDR_EXPR, expr, 0);
5056           expr = build_nop (reference_type, expr);
5057           return convert_from_reference (expr);
5058         }
5059       else
5060         {
5061           expr = decay_conversion (expr);
5062           /* build_c_cast puts on a NOP_EXPR to make the result not an
5063              lvalue.  Strip such NOP_EXPRs if VALUE is being used in
5064              non-lvalue context.  */
5065           if (TREE_CODE (expr) == NOP_EXPR
5066               && TREE_TYPE (expr) == TREE_TYPE (TREE_OPERAND (expr, 0)))
5067             expr = TREE_OPERAND (expr, 0);
5068           return build_nop (dst_type, expr);
5069         }
5070     }
5071
5072   if (complain)
5073     error ("invalid const_cast from type %qT to type %qT",
5074            src_type, dst_type);
5075   return error_mark_node;
5076 }
5077
5078 tree
5079 build_const_cast (tree type, tree expr)
5080 {
5081   if (type == error_mark_node || error_operand_p (expr))
5082     return error_mark_node;
5083
5084   if (processing_template_decl)
5085     {
5086       tree t = build_min (CONST_CAST_EXPR, type, expr);
5087
5088       if (!TREE_SIDE_EFFECTS (t)
5089           && type_dependent_expression_p (expr))
5090         /* There might turn out to be side effects inside expr.  */
5091         TREE_SIDE_EFFECTS (t) = 1;
5092       return convert_from_reference (t);
5093     }
5094
5095   return build_const_cast_1 (type, expr, /*complain=*/true,
5096                              /*valid_p=*/NULL);
5097 }
5098
5099 /* Build an expression representing an explicit C-style cast to type
5100    TYPE of expression EXPR.  */
5101
5102 tree
5103 build_c_cast (tree type, tree expr)
5104 {
5105   tree value = expr;
5106   tree result;
5107   bool valid_p;
5108
5109   if (type == error_mark_node || error_operand_p (expr))
5110     return error_mark_node;
5111
5112   if (processing_template_decl)
5113     {
5114       tree t = build_min (CAST_EXPR, type,
5115                           tree_cons (NULL_TREE, value, NULL_TREE));
5116       /* We don't know if it will or will not have side effects.  */
5117       TREE_SIDE_EFFECTS (t) = 1;
5118       return convert_from_reference (t);
5119     }
5120
5121   /* Casts to a (pointer to a) specific ObjC class (or 'id' or
5122      'Class') should always be retained, because this information aids
5123      in method lookup.  */
5124   if (objc_is_object_ptr (type)
5125       && objc_is_object_ptr (TREE_TYPE (expr)))
5126     return build_nop (type, expr);
5127
5128   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
5129      Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
5130   if (TREE_CODE (type) != REFERENCE_TYPE
5131       && TREE_CODE (value) == NOP_EXPR
5132       && TREE_TYPE (value) == TREE_TYPE (TREE_OPERAND (value, 0)))
5133     value = TREE_OPERAND (value, 0);
5134
5135   if (TREE_CODE (type) == ARRAY_TYPE)
5136     {
5137       /* Allow casting from T1* to T2[] because Cfront allows it.
5138          NIHCL uses it. It is not valid ISO C++ however.  */
5139       if (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE)
5140         {
5141           pedwarn ("ISO C++ forbids casting to an array type %qT", type);
5142           type = build_pointer_type (TREE_TYPE (type));
5143         }
5144       else
5145         {
5146           error ("ISO C++ forbids casting to an array type %qT", type);
5147           return error_mark_node;
5148         }
5149     }
5150
5151   if (TREE_CODE (type) == FUNCTION_TYPE
5152       || TREE_CODE (type) == METHOD_TYPE)
5153     {
5154       error ("invalid cast to function type %qT", type);
5155       return error_mark_node;
5156     }
5157
5158   /* A C-style cast can be a const_cast.  */
5159   result = build_const_cast_1 (type, value, /*complain=*/false,
5160                                &valid_p);
5161   if (valid_p)
5162     return result;
5163
5164   /* Or a static cast.  */
5165   result = build_static_cast_1 (type, value, /*c_cast_p=*/true,
5166                                 &valid_p);
5167   /* Or a reinterpret_cast.  */
5168   if (!valid_p)
5169     result = build_reinterpret_cast_1 (type, value, /*c_cast_p=*/true,
5170                                        &valid_p);
5171   /* The static_cast or reinterpret_cast may be followed by a
5172      const_cast.  */
5173   if (valid_p
5174       /* A valid cast may result in errors if, for example, a
5175          conversion to am ambiguous base class is required.  */
5176       && !error_operand_p (result))
5177     {
5178       tree result_type;
5179
5180       /* Non-class rvalues always have cv-unqualified type.  */
5181       if (!CLASS_TYPE_P (type))
5182         type = TYPE_MAIN_VARIANT (type);
5183       result_type = TREE_TYPE (result);
5184       if (!CLASS_TYPE_P (result_type))
5185         result_type = TYPE_MAIN_VARIANT (result_type);
5186       /* If the type of RESULT does not match TYPE, perform a
5187          const_cast to make it match.  If the static_cast or
5188          reinterpret_cast succeeded, we will differ by at most
5189          cv-qualification, so the follow-on const_cast is guaranteed
5190          to succeed.  */
5191       if (!same_type_p (non_reference (type), non_reference (result_type)))
5192         {
5193           result = build_const_cast_1 (type, result, false, &valid_p);
5194           gcc_assert (valid_p);
5195         }
5196       return result;
5197     }
5198
5199   return error_mark_node;
5200 }
5201 \f
5202 /* Build an assignment expression of lvalue LHS from value RHS.
5203    MODIFYCODE is the code for a binary operator that we use
5204    to combine the old value of LHS with RHS to get the new value.
5205    Or else MODIFYCODE is NOP_EXPR meaning do a simple assignment.
5206
5207    C++: If MODIFYCODE is INIT_EXPR, then leave references unbashed.  */
5208
5209 tree
5210 build_modify_expr (tree lhs, enum tree_code modifycode, tree rhs)
5211 {
5212   tree result;
5213   tree newrhs = rhs;
5214   tree lhstype = TREE_TYPE (lhs);
5215   tree olhstype = lhstype;
5216   tree olhs = NULL_TREE;
5217   bool plain_assign = (modifycode == NOP_EXPR);
5218
5219   /* Avoid duplicate error messages from operands that had errors.  */
5220   if (lhs == error_mark_node || rhs == error_mark_node)
5221     return error_mark_node;
5222
5223   /* Handle control structure constructs used as "lvalues".  */
5224   switch (TREE_CODE (lhs))
5225     {
5226       /* Handle --foo = 5; as these are valid constructs in C++.  */
5227     case PREDECREMENT_EXPR:
5228     case PREINCREMENT_EXPR:
5229       if (TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 0)))
5230         lhs = build2 (TREE_CODE (lhs), TREE_TYPE (lhs),
5231                       stabilize_reference (TREE_OPERAND (lhs, 0)),
5232                       TREE_OPERAND (lhs, 1));
5233       return build2 (COMPOUND_EXPR, lhstype,
5234                      lhs,
5235                      build_modify_expr (TREE_OPERAND (lhs, 0),
5236                                         modifycode, rhs));
5237
5238       /* Handle (a, b) used as an "lvalue".  */
5239     case COMPOUND_EXPR:
5240       newrhs = build_modify_expr (TREE_OPERAND (lhs, 1),
5241                                   modifycode, rhs);
5242       if (newrhs == error_mark_node)
5243         return error_mark_node;
5244       return build2 (COMPOUND_EXPR, lhstype,
5245                      TREE_OPERAND (lhs, 0), newrhs);
5246
5247     case MODIFY_EXPR:
5248       if (TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 0)))
5249         lhs = build2 (TREE_CODE (lhs), TREE_TYPE (lhs),
5250                       stabilize_reference (TREE_OPERAND (lhs, 0)),
5251                       TREE_OPERAND (lhs, 1));
5252       newrhs = build_modify_expr (TREE_OPERAND (lhs, 0), modifycode, rhs);
5253       if (newrhs == error_mark_node)
5254         return error_mark_node;
5255       return build2 (COMPOUND_EXPR, lhstype, lhs, newrhs);
5256
5257     case MIN_EXPR:
5258     case MAX_EXPR:
5259       /* MIN_EXPR and MAX_EXPR are currently only permitted as lvalues,
5260          when neither operand has side-effects.  */
5261       if (!lvalue_or_else (lhs, lv_assign))
5262         return error_mark_node;
5263
5264       gcc_assert (!TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 0))
5265                   && !TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 1)));
5266
5267       lhs = build3 (COND_EXPR, TREE_TYPE (lhs),
5268                     build2 (TREE_CODE (lhs) == MIN_EXPR ? LE_EXPR : GE_EXPR,
5269                             boolean_type_node,
5270                             TREE_OPERAND (lhs, 0),
5271                             TREE_OPERAND (lhs, 1)),
5272                     TREE_OPERAND (lhs, 0),
5273                     TREE_OPERAND (lhs, 1));
5274       /* Fall through.  */
5275
5276       /* Handle (a ? b : c) used as an "lvalue".  */
5277     case COND_EXPR:
5278       {
5279         /* Produce (a ? (b = rhs) : (c = rhs))
5280            except that the RHS goes through a save-expr
5281            so the code to compute it is only emitted once.  */
5282         tree cond;
5283         tree preeval = NULL_TREE;
5284
5285         rhs = stabilize_expr (rhs, &preeval);
5286
5287         /* Check this here to avoid odd errors when trying to convert
5288            a throw to the type of the COND_EXPR.  */
5289         if (!lvalue_or_else (lhs, lv_assign))
5290           return error_mark_node;
5291
5292         cond = build_conditional_expr
5293           (TREE_OPERAND (lhs, 0),
5294            build_modify_expr (cp_convert (TREE_TYPE (lhs),
5295                                           TREE_OPERAND (lhs, 1)),
5296                               modifycode, rhs),
5297            build_modify_expr (cp_convert (TREE_TYPE (lhs),
5298                                           TREE_OPERAND (lhs, 2)),
5299                               modifycode, rhs));
5300
5301         if (cond == error_mark_node)
5302           return cond;
5303         /* Make sure the code to compute the rhs comes out
5304            before the split.  */
5305         if (preeval)
5306           cond = build2 (COMPOUND_EXPR, TREE_TYPE (lhs), preeval, cond);
5307         return cond;
5308       }
5309
5310     default:
5311       break;
5312     }
5313
5314   if (modifycode == INIT_EXPR)
5315     {
5316       if (TREE_CODE (rhs) == CONSTRUCTOR)
5317         {
5318           if (! same_type_p (TREE_TYPE (rhs), lhstype))
5319             /* Call convert to generate an error; see PR 11063.  */
5320             rhs = convert (lhstype, rhs);
5321           result = build2 (INIT_EXPR, lhstype, lhs, rhs);
5322           TREE_SIDE_EFFECTS (result) = 1;
5323           return result;
5324         }
5325       else if (! IS_AGGR_TYPE (lhstype))
5326         /* Do the default thing.  */;
5327       else
5328         {
5329           result = build_special_member_call (lhs, complete_ctor_identifier,
5330                                               build_tree_list (NULL_TREE, rhs),
5331                                               lhstype, LOOKUP_NORMAL);
5332           if (result == NULL_TREE)
5333             return error_mark_node;
5334           return result;
5335         }
5336     }
5337   else
5338     {
5339       lhs = require_complete_type (lhs);
5340       if (lhs == error_mark_node)
5341         return error_mark_node;
5342
5343       if (modifycode == NOP_EXPR)
5344         {
5345           /* `operator=' is not an inheritable operator.  */
5346           if (! IS_AGGR_TYPE (lhstype))
5347             /* Do the default thing.  */;
5348           else
5349             {
5350               result = build_new_op (MODIFY_EXPR, LOOKUP_NORMAL,
5351                                      lhs, rhs, make_node (NOP_EXPR),
5352                                      /*overloaded_p=*/NULL);
5353               if (result == NULL_TREE)
5354                 return error_mark_node;
5355               return result;
5356             }
5357           lhstype = olhstype;
5358         }
5359       else
5360         {
5361           /* A binary op has been requested.  Combine the old LHS
5362              value with the RHS producing the value we should actually
5363              store into the LHS.  */
5364
5365           gcc_assert (!PROMOTES_TO_AGGR_TYPE (lhstype, REFERENCE_TYPE));
5366           lhs = stabilize_reference (lhs);
5367           newrhs = cp_build_binary_op (modifycode, lhs, rhs);
5368           if (newrhs == error_mark_node)
5369             {
5370               error ("  in evaluation of %<%Q(%#T, %#T)%>", modifycode,
5371                      TREE_TYPE (lhs), TREE_TYPE (rhs));
5372               return error_mark_node;
5373             }
5374
5375           /* Now it looks like a plain assignment.  */
5376           modifycode = NOP_EXPR;
5377         }
5378       gcc_assert (TREE_CODE (lhstype) != REFERENCE_TYPE);
5379       gcc_assert (TREE_CODE (TREE_TYPE (newrhs)) != REFERENCE_TYPE);
5380     }
5381
5382   /* The left-hand side must be an lvalue.  */
5383   if (!lvalue_or_else (lhs, lv_assign))
5384     return error_mark_node;
5385
5386   /* Warn about modifying something that is `const'.  Don't warn if
5387      this is initialization.  */
5388   if (modifycode != INIT_EXPR
5389       && (TREE_READONLY (lhs) || CP_TYPE_CONST_P (lhstype)
5390           /* Functions are not modifiable, even though they are
5391              lvalues.  */
5392           || TREE_CODE (TREE_TYPE (lhs)) == FUNCTION_TYPE
5393           || TREE_CODE (TREE_TYPE (lhs)) == METHOD_TYPE
5394           /* If it's an aggregate and any field is const, then it is
5395              effectively const.  */
5396           || (CLASS_TYPE_P (lhstype)
5397               && C_TYPE_FIELDS_READONLY (lhstype))))
5398     readonly_error (lhs, "assignment", 0);
5399
5400   /* If storing into a structure or union member, it has probably been
5401      given type `int'.  Compute the type that would go with the actual
5402      amount of storage the member occupies.  */
5403
5404   if (TREE_CODE (lhs) == COMPONENT_REF
5405       && (TREE_CODE (lhstype) == INTEGER_TYPE
5406           || TREE_CODE (lhstype) == REAL_TYPE
5407           || TREE_CODE (lhstype) == ENUMERAL_TYPE))
5408     {
5409       lhstype = TREE_TYPE (get_unwidened (lhs, 0));
5410
5411       /* If storing in a field that is in actuality a short or narrower
5412          than one, we must store in the field in its actual type.  */
5413
5414       if (lhstype != TREE_TYPE (lhs))
5415         {
5416           /* Avoid warnings converting integral types back into enums for
5417              enum bit fields.  */
5418           if (TREE_CODE (lhstype) == INTEGER_TYPE
5419               && TREE_CODE (olhstype) == ENUMERAL_TYPE)
5420             {
5421               if (TREE_SIDE_EFFECTS (lhs))
5422                 lhs = stabilize_reference (lhs);
5423               olhs = lhs;
5424             }
5425           lhs = copy_node (lhs);
5426           TREE_TYPE (lhs) = lhstype;
5427         }
5428     }
5429
5430   /* Convert new value to destination type.  */
5431
5432   if (TREE_CODE (lhstype) == ARRAY_TYPE)
5433     {
5434       int from_array;
5435
5436       if (!same_or_base_type_p (TYPE_MAIN_VARIANT (lhstype),
5437                                 TYPE_MAIN_VARIANT (TREE_TYPE (rhs))))
5438         {
5439           error ("incompatible types in assignment of %qT to %qT",
5440                  TREE_TYPE (rhs), lhstype);
5441           return error_mark_node;
5442         }
5443
5444       /* Allow array assignment in compiler-generated code.  */
5445       if (! DECL_ARTIFICIAL (current_function_decl))
5446         pedwarn ("ISO C++ forbids assignment of arrays");
5447
5448       from_array = TREE_CODE (TREE_TYPE (newrhs)) == ARRAY_TYPE
5449                    ? 1 + (modifycode != INIT_EXPR): 0;
5450       return build_vec_init (lhs, NULL_TREE, newrhs, from_array);
5451     }
5452
5453   if (modifycode == INIT_EXPR)
5454     newrhs = convert_for_initialization (lhs, lhstype, newrhs, LOOKUP_NORMAL,
5455                                          "initialization", NULL_TREE, 0);
5456   else
5457     {
5458       /* Avoid warnings on enum bit fields.  */
5459       if (TREE_CODE (olhstype) == ENUMERAL_TYPE
5460           && TREE_CODE (lhstype) == INTEGER_TYPE)
5461         {
5462           newrhs = convert_for_assignment (olhstype, newrhs, "assignment",
5463                                            NULL_TREE, 0);
5464           newrhs = convert_force (lhstype, newrhs, 0);
5465         }
5466       else
5467         newrhs = convert_for_assignment (lhstype, newrhs, "assignment",
5468                                          NULL_TREE, 0);
5469       if (TREE_CODE (newrhs) == CALL_EXPR
5470           && TYPE_NEEDS_CONSTRUCTING (lhstype))
5471         newrhs = build_cplus_new (lhstype, newrhs);
5472
5473       /* Can't initialize directly from a TARGET_EXPR, since that would
5474          cause the lhs to be constructed twice, and possibly result in
5475          accidental self-initialization.  So we force the TARGET_EXPR to be
5476          expanded without a target.  */
5477       if (TREE_CODE (newrhs) == TARGET_EXPR)
5478         newrhs = build2 (COMPOUND_EXPR, TREE_TYPE (newrhs), newrhs,
5479                          TREE_OPERAND (newrhs, 0));
5480     }
5481
5482   if (newrhs == error_mark_node)
5483     return error_mark_node;
5484
5485   result = build2 (modifycode == NOP_EXPR ? MODIFY_EXPR : INIT_EXPR,
5486                    lhstype, lhs, newrhs);
5487
5488   TREE_SIDE_EFFECTS (result) = 1;
5489   if (!plain_assign)
5490     TREE_NO_WARNING (result) = 1;
5491
5492   /* If we got the LHS in a different type for storing in,
5493      convert the result back to the nominal type of LHS
5494      so that the value we return always has the same type
5495      as the LHS argument.  */
5496
5497   if (olhstype == TREE_TYPE (result))
5498     return result;
5499   if (olhs)
5500     {
5501       result = build2 (COMPOUND_EXPR, olhstype, result, olhs);
5502       TREE_NO_WARNING (result) = 1;
5503       return result;
5504     }
5505   return convert_for_assignment (olhstype, result, "assignment",
5506                                  NULL_TREE, 0);
5507 }
5508
5509 tree
5510 build_x_modify_expr (tree lhs, enum tree_code modifycode, tree rhs)
5511 {
5512   if (processing_template_decl)
5513     return build_min_nt (MODOP_EXPR, lhs,
5514                          build_min_nt (modifycode, NULL_TREE, NULL_TREE), rhs);
5515
5516   if (modifycode != NOP_EXPR)
5517     {
5518       tree rval = build_new_op (MODIFY_EXPR, LOOKUP_NORMAL, lhs, rhs,
5519                                 make_node (modifycode),
5520                                 /*overloaded_p=*/NULL);
5521       if (rval)
5522         {
5523           TREE_NO_WARNING (rval) = 1;
5524           return rval;
5525         }
5526     }
5527   return build_modify_expr (lhs, modifycode, rhs);
5528 }
5529
5530 \f
5531 /* Get difference in deltas for different pointer to member function
5532    types.  Returns an integer constant of type PTRDIFF_TYPE_NODE.  If
5533    the conversion is invalid, the constant is zero.  If
5534    ALLOW_INVERSE_P is true, then allow reverse conversions as well.
5535    If C_CAST_P is true this conversion is taking place as part of a
5536    C-style cast.
5537
5538    Note that the naming of FROM and TO is kind of backwards; the return
5539    value is what we add to a TO in order to get a FROM.  They are named
5540    this way because we call this function to find out how to convert from
5541    a pointer to member of FROM to a pointer to member of TO.  */
5542
5543 static tree
5544 get_delta_difference (tree from, tree to,
5545                       bool allow_inverse_p,
5546                       bool c_cast_p)
5547 {
5548   tree binfo;
5549   tree virt_binfo;
5550   base_kind kind;
5551   tree result;
5552
5553   /* Assume no conversion is required.  */
5554   result = integer_zero_node;
5555   binfo = lookup_base (to, from, c_cast_p ? ba_unique : ba_check, &kind);
5556   if (kind == bk_inaccessible || kind == bk_ambig)
5557     error ("   in pointer to member function conversion");
5558   else if (!binfo)
5559     {
5560       if (!allow_inverse_p)
5561         {
5562           error_not_base_type (from, to);
5563           error ("   in pointer to member conversion");
5564         }
5565       else
5566         {
5567           binfo = lookup_base (from, to, c_cast_p ? ba_unique : ba_check,
5568                                &kind);
5569           if (binfo)
5570             {
5571               virt_binfo = binfo_from_vbase (binfo);
5572               if (virt_binfo)
5573                 /* This is a reinterpret cast, we choose to do nothing.  */
5574                 warning ("pointer to member cast via virtual base %qT",
5575                          BINFO_TYPE (virt_binfo));
5576               else
5577                 result = size_diffop (size_zero_node, BINFO_OFFSET (binfo));
5578             }
5579         }
5580     }
5581   else
5582     {
5583       virt_binfo = binfo_from_vbase (binfo);
5584       if (!virt_binfo)
5585         result = BINFO_OFFSET (binfo);
5586       else
5587         {
5588           /* This is a reinterpret cast, we choose to do nothing.  */
5589           if (allow_inverse_p)
5590             warning ("pointer to member cast via virtual base %qT",
5591                      BINFO_TYPE (virt_binfo));
5592           else
5593             error ("pointer to member conversion via virtual base %qT",
5594                    BINFO_TYPE (virt_binfo));
5595         }
5596     }
5597
5598   return fold_if_not_in_template (convert_to_integer (ptrdiff_type_node,
5599                                                       result));
5600 }
5601
5602 /* Return a constructor for the pointer-to-member-function TYPE using
5603    the other components as specified.  */
5604
5605 tree
5606 build_ptrmemfunc1 (tree type, tree delta, tree pfn)
5607 {
5608   tree u = NULL_TREE;
5609   tree delta_field;
5610   tree pfn_field;
5611
5612   /* Pull the FIELD_DECLs out of the type.  */
5613   pfn_field = TYPE_FIELDS (type);
5614   delta_field = TREE_CHAIN (pfn_field);
5615
5616   /* Make sure DELTA has the type we want.  */
5617   delta = convert_and_check (delta_type_node, delta);
5618
5619   /* Finish creating the initializer.  */
5620   u = tree_cons (pfn_field, pfn,
5621                  build_tree_list (delta_field, delta));
5622   u = build_constructor (type, u);
5623   TREE_CONSTANT (u) = TREE_CONSTANT (pfn) & TREE_CONSTANT (delta);
5624   TREE_INVARIANT (u) = TREE_INVARIANT (pfn) & TREE_INVARIANT (delta);
5625   TREE_STATIC (u) = (TREE_CONSTANT (u)
5626                      && (initializer_constant_valid_p (pfn, TREE_TYPE (pfn))
5627                          != NULL_TREE)
5628                      && (initializer_constant_valid_p (delta, TREE_TYPE (delta))
5629                          != NULL_TREE));
5630   return u;
5631 }
5632
5633 /* Build a constructor for a pointer to member function.  It can be
5634    used to initialize global variables, local variable, or used
5635    as a value in expressions.  TYPE is the POINTER to METHOD_TYPE we
5636    want to be.
5637
5638    If FORCE is nonzero, then force this conversion, even if
5639    we would rather not do it.  Usually set when using an explicit
5640    cast.  A C-style cast is being processed iff C_CAST_P is true.
5641
5642    Return error_mark_node, if something goes wrong.  */
5643
5644 tree
5645 build_ptrmemfunc (tree type, tree pfn, int force, bool c_cast_p)
5646 {
5647   tree fn;
5648   tree pfn_type;
5649   tree to_type;
5650
5651   if (error_operand_p (pfn))
5652     return error_mark_node;
5653
5654   pfn_type = TREE_TYPE (pfn);
5655   to_type = build_ptrmemfunc_type (type);
5656
5657   /* Handle multiple conversions of pointer to member functions.  */
5658   if (TYPE_PTRMEMFUNC_P (pfn_type))
5659     {
5660       tree delta = NULL_TREE;
5661       tree npfn = NULL_TREE;
5662       tree n;
5663
5664       if (!force
5665           && !can_convert_arg (to_type, TREE_TYPE (pfn), pfn))
5666         error ("invalid conversion to type %qT from type %qT",
5667                to_type, pfn_type);
5668
5669       n = get_delta_difference (TYPE_PTRMEMFUNC_OBJECT_TYPE (pfn_type),
5670                                 TYPE_PTRMEMFUNC_OBJECT_TYPE (to_type),
5671                                 force,
5672                                 c_cast_p);
5673
5674       /* We don't have to do any conversion to convert a
5675          pointer-to-member to its own type.  But, we don't want to
5676          just return a PTRMEM_CST if there's an explicit cast; that
5677          cast should make the expression an invalid template argument.  */
5678       if (TREE_CODE (pfn) != PTRMEM_CST)
5679         {
5680           if (same_type_p (to_type, pfn_type))
5681             return pfn;
5682           else if (integer_zerop (n))
5683             return build_reinterpret_cast (to_type, pfn);
5684         }
5685
5686       if (TREE_SIDE_EFFECTS (pfn))
5687         pfn = save_expr (pfn);
5688
5689       /* Obtain the function pointer and the current DELTA.  */
5690       if (TREE_CODE (pfn) == PTRMEM_CST)
5691         expand_ptrmemfunc_cst (pfn, &delta, &npfn);
5692       else
5693         {
5694           npfn = build_ptrmemfunc_access_expr (pfn, pfn_identifier);
5695           delta = build_ptrmemfunc_access_expr (pfn, delta_identifier);
5696         }
5697
5698       /* Just adjust the DELTA field.  */
5699       gcc_assert  (same_type_ignoring_top_level_qualifiers_p
5700                    (TREE_TYPE (delta), ptrdiff_type_node));
5701       if (TARGET_PTRMEMFUNC_VBIT_LOCATION == ptrmemfunc_vbit_in_delta)
5702         n = cp_build_binary_op (LSHIFT_EXPR, n, integer_one_node);
5703       delta = cp_build_binary_op (PLUS_EXPR, delta, n);
5704       return build_ptrmemfunc1 (to_type, delta, npfn);
5705     }
5706
5707   /* Handle null pointer to member function conversions.  */
5708   if (integer_zerop (pfn))
5709     {
5710       pfn = build_c_cast (type, integer_zero_node);
5711       return build_ptrmemfunc1 (to_type,
5712                                 integer_zero_node,
5713                                 pfn);
5714     }
5715
5716   if (type_unknown_p (pfn))
5717     return instantiate_type (type, pfn, tf_error | tf_warning);
5718
5719   fn = TREE_OPERAND (pfn, 0);
5720   gcc_assert (TREE_CODE (fn) == FUNCTION_DECL);
5721   return make_ptrmem_cst (to_type, fn);
5722 }
5723
5724 /* Return the DELTA, IDX, PFN, and DELTA2 values for the PTRMEM_CST
5725    given by CST.
5726
5727    ??? There is no consistency as to the types returned for the above
5728    values.  Some code acts as if it were a sizetype and some as if it were
5729    integer_type_node.  */
5730
5731 void
5732 expand_ptrmemfunc_cst (tree cst, tree *delta, tree *pfn)
5733 {
5734   tree type = TREE_TYPE (cst);
5735   tree fn = PTRMEM_CST_MEMBER (cst);
5736   tree ptr_class, fn_class;
5737
5738   gcc_assert (TREE_CODE (fn) == FUNCTION_DECL);
5739
5740   /* The class that the function belongs to.  */
5741   fn_class = DECL_CONTEXT (fn);
5742
5743   /* The class that we're creating a pointer to member of.  */
5744   ptr_class = TYPE_PTRMEMFUNC_OBJECT_TYPE (type);
5745
5746   /* First, calculate the adjustment to the function's class.  */
5747   *delta = get_delta_difference (fn_class, ptr_class, /*force=*/0,
5748                                  /*c_cast_p=*/0);
5749
5750   if (!DECL_VIRTUAL_P (fn))
5751     *pfn = convert (TYPE_PTRMEMFUNC_FN_TYPE (type), build_addr_func (fn));
5752   else
5753     {
5754       /* If we're dealing with a virtual function, we have to adjust 'this'
5755          again, to point to the base which provides the vtable entry for
5756          fn; the call will do the opposite adjustment.  */
5757       tree orig_class = DECL_CONTEXT (fn);
5758       tree binfo = binfo_or_else (orig_class, fn_class);
5759       *delta = build2 (PLUS_EXPR, TREE_TYPE (*delta),
5760                        *delta, BINFO_OFFSET (binfo));
5761       *delta = fold_if_not_in_template (*delta);
5762
5763       /* We set PFN to the vtable offset at which the function can be
5764          found, plus one (unless ptrmemfunc_vbit_in_delta, in which
5765          case delta is shifted left, and then incremented).  */
5766       *pfn = DECL_VINDEX (fn);
5767       *pfn = build2 (MULT_EXPR, integer_type_node, *pfn,
5768                      TYPE_SIZE_UNIT (vtable_entry_type));
5769       *pfn = fold_if_not_in_template (*pfn);
5770
5771       switch (TARGET_PTRMEMFUNC_VBIT_LOCATION)
5772         {
5773         case ptrmemfunc_vbit_in_pfn:
5774           *pfn = build2 (PLUS_EXPR, integer_type_node, *pfn,
5775                          integer_one_node);
5776           *pfn = fold_if_not_in_template (*pfn);
5777           break;
5778
5779         case ptrmemfunc_vbit_in_delta:
5780           *delta = build2 (LSHIFT_EXPR, TREE_TYPE (*delta),
5781                            *delta, integer_one_node);
5782           *delta = fold_if_not_in_template (*delta);
5783           *delta = build2 (PLUS_EXPR, TREE_TYPE (*delta),
5784                            *delta, integer_one_node);
5785           *delta = fold_if_not_in_template (*delta);
5786           break;
5787
5788         default:
5789           gcc_unreachable ();
5790         }
5791
5792       *pfn = build_nop (TYPE_PTRMEMFUNC_FN_TYPE (type), *pfn);
5793       *pfn = fold_if_not_in_template (*pfn);
5794     }
5795 }
5796
5797 /* Return an expression for PFN from the pointer-to-member function
5798    given by T.  */
5799
5800 tree
5801 pfn_from_ptrmemfunc (tree t)
5802 {
5803   if (TREE_CODE (t) == PTRMEM_CST)
5804     {
5805       tree delta;
5806       tree pfn;
5807
5808       expand_ptrmemfunc_cst (t, &delta, &pfn);
5809       if (pfn)
5810         return pfn;
5811     }
5812
5813   return build_ptrmemfunc_access_expr (t, pfn_identifier);
5814 }
5815
5816 /* Expression EXPR is about to be implicitly converted to TYPE.  Warn
5817    if this is a potentially dangerous thing to do.  Returns a possibly
5818    marked EXPR.  */
5819
5820 tree
5821 dubious_conversion_warnings (tree type, tree expr,
5822                              const char *errtype, tree fndecl, int parmnum)
5823 {
5824   type = non_reference (type);
5825
5826   /* Issue warnings about peculiar, but valid, uses of NULL.  */
5827   if (ARITHMETIC_TYPE_P (type) && expr == null_node)
5828     {
5829       if (fndecl)
5830         warning ("passing NULL used for non-pointer %s %P of %qD",
5831                  errtype, parmnum, fndecl);
5832       else
5833         warning ("%s to non-pointer type %qT from NULL", errtype, type);
5834     }
5835
5836   /* Warn about assigning a floating-point type to an integer type.  */
5837   if (TREE_CODE (TREE_TYPE (expr)) == REAL_TYPE
5838       && TREE_CODE (type) == INTEGER_TYPE)
5839     {
5840       if (fndecl)
5841         warning ("passing %qT for %s %P of %qD",
5842                  TREE_TYPE (expr), errtype, parmnum, fndecl);
5843       else
5844         warning ("%s to %qT from %qT", errtype, type, TREE_TYPE (expr));
5845     }
5846   /* And warn about assigning a negative value to an unsigned
5847      variable.  */
5848   else if (TYPE_UNSIGNED (type) && TREE_CODE (type) != BOOLEAN_TYPE)
5849     {
5850       if (TREE_CODE (expr) == INTEGER_CST && TREE_NEGATED_INT (expr))
5851         {
5852           if (fndecl)
5853             warning ("passing negative value %qE for %s %P of %qD",
5854                      expr, errtype, parmnum, fndecl);
5855           else
5856             warning ("%s of negative value %qE to %qT", errtype, expr, type);
5857         }
5858
5859       overflow_warning (expr);
5860
5861       if (TREE_CONSTANT (expr))
5862         expr = fold_if_not_in_template (expr);
5863     }
5864   return expr;
5865 }
5866
5867 /* Convert value RHS to type TYPE as preparation for an assignment to
5868    an lvalue of type TYPE.  ERRTYPE is a string to use in error
5869    messages: "assignment", "return", etc.  If FNDECL is non-NULL, we
5870    are doing the conversion in order to pass the PARMNUMth argument of
5871    FNDECL.  */
5872
5873 static tree
5874 convert_for_assignment (tree type, tree rhs,
5875                         const char *errtype, tree fndecl, int parmnum)
5876 {
5877   tree rhstype;
5878   enum tree_code coder;
5879
5880   /* Strip NON_LVALUE_EXPRs since we aren't using as an lvalue.  */
5881   if (TREE_CODE (rhs) == NON_LVALUE_EXPR)
5882     rhs = TREE_OPERAND (rhs, 0);
5883
5884   rhstype = TREE_TYPE (rhs);
5885   coder = TREE_CODE (rhstype);
5886
5887   if (TREE_CODE (type) == VECTOR_TYPE && coder == VECTOR_TYPE
5888       && vector_types_convertible_p (type, rhstype))
5889     return convert (type, rhs);
5890
5891   if (rhs == error_mark_node || rhstype == error_mark_node)
5892     return error_mark_node;
5893   if (TREE_CODE (rhs) == TREE_LIST && TREE_VALUE (rhs) == error_mark_node)
5894     return error_mark_node;
5895
5896   /* The RHS of an assignment cannot have void type.  */
5897   if (coder == VOID_TYPE)
5898     {
5899       error ("void value not ignored as it ought to be");
5900       return error_mark_node;
5901     }
5902
5903   /* Simplify the RHS if possible.  */
5904   if (TREE_CODE (rhs) == CONST_DECL)
5905     rhs = DECL_INITIAL (rhs);
5906
5907   /* [expr.ass]
5908
5909      The expression is implicitly converted (clause _conv_) to the
5910      cv-unqualified type of the left operand.
5911
5912      We allow bad conversions here because by the time we get to this point
5913      we are committed to doing the conversion.  If we end up doing a bad
5914      conversion, convert_like will complain.  */
5915   if (!can_convert_arg_bad (type, rhstype, rhs))
5916     {
5917       /* When -Wno-pmf-conversions is use, we just silently allow
5918          conversions from pointers-to-members to plain pointers.  If
5919          the conversion doesn't work, cp_convert will complain.  */
5920       if (!warn_pmf2ptr
5921           && TYPE_PTR_P (type)
5922           && TYPE_PTRMEMFUNC_P (rhstype))
5923         rhs = cp_convert (strip_top_quals (type), rhs);
5924       else
5925         {
5926           /* If the right-hand side has unknown type, then it is an
5927              overloaded function.  Call instantiate_type to get error
5928              messages.  */
5929           if (rhstype == unknown_type_node)
5930             instantiate_type (type, rhs, tf_error | tf_warning);
5931           else if (fndecl)
5932             error ("cannot convert %qT to %qT for argument %qP to %qD",
5933                    rhstype, type, parmnum, fndecl);
5934           else
5935             error ("cannot convert %qT to %qT in %s", rhstype, type, errtype);
5936           return error_mark_node;
5937         }
5938     }
5939   return perform_implicit_conversion (strip_top_quals (type), rhs);
5940 }
5941
5942 /* Convert RHS to be of type TYPE.
5943    If EXP is nonzero, it is the target of the initialization.
5944    ERRTYPE is a string to use in error messages.
5945
5946    Two major differences between the behavior of
5947    `convert_for_assignment' and `convert_for_initialization'
5948    are that references are bashed in the former, while
5949    copied in the latter, and aggregates are assigned in
5950    the former (operator=) while initialized in the
5951    latter (X(X&)).
5952
5953    If using constructor make sure no conversion operator exists, if one does
5954    exist, an ambiguity exists.
5955
5956    If flags doesn't include LOOKUP_COMPLAIN, don't complain about anything.  */
5957
5958 tree
5959 convert_for_initialization (tree exp, tree type, tree rhs, int flags,
5960                             const char *errtype, tree fndecl, int parmnum)
5961 {
5962   enum tree_code codel = TREE_CODE (type);
5963   tree rhstype;
5964   enum tree_code coder;
5965
5966   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
5967      Strip such NOP_EXPRs, since RHS is used in non-lvalue context.  */
5968   if (TREE_CODE (rhs) == NOP_EXPR
5969       && TREE_TYPE (rhs) == TREE_TYPE (TREE_OPERAND (rhs, 0))
5970       && codel != REFERENCE_TYPE)
5971     rhs = TREE_OPERAND (rhs, 0);
5972
5973   if (rhs == error_mark_node
5974       || (TREE_CODE (rhs) == TREE_LIST && TREE_VALUE (rhs) == error_mark_node))
5975     return error_mark_node;
5976
5977   if ((TREE_CODE (TREE_TYPE (rhs)) == ARRAY_TYPE
5978        && TREE_CODE (type) != ARRAY_TYPE
5979        && (TREE_CODE (type) != REFERENCE_TYPE
5980            || TREE_CODE (TREE_TYPE (type)) != ARRAY_TYPE))
5981       || (TREE_CODE (TREE_TYPE (rhs)) == FUNCTION_TYPE
5982           && (TREE_CODE (type) != REFERENCE_TYPE
5983               || TREE_CODE (TREE_TYPE (type)) != FUNCTION_TYPE))
5984       || TREE_CODE (TREE_TYPE (rhs)) == METHOD_TYPE)
5985     rhs = decay_conversion (rhs);
5986
5987   rhstype = TREE_TYPE (rhs);
5988   coder = TREE_CODE (rhstype);
5989
5990   if (coder == ERROR_MARK)
5991     return error_mark_node;
5992
5993   /* We accept references to incomplete types, so we can
5994      return here before checking if RHS is of complete type.  */
5995
5996   if (codel == REFERENCE_TYPE)
5997     {
5998       /* This should eventually happen in convert_arguments.  */
5999       int savew = 0, savee = 0;
6000
6001       if (fndecl)
6002         savew = warningcount, savee = errorcount;
6003       rhs = initialize_reference (type, rhs, /*decl=*/NULL_TREE,
6004                                   /*cleanup=*/NULL);
6005       if (fndecl)
6006         {
6007           if (warningcount > savew)
6008             cp_warning_at ("in passing argument %P of %q+D", parmnum, fndecl);
6009           else if (errorcount > savee)
6010             cp_error_at ("in passing argument %P of %q+D", parmnum, fndecl);
6011         }
6012       return rhs;
6013     }
6014
6015   if (exp != 0)
6016     exp = require_complete_type (exp);
6017   if (exp == error_mark_node)
6018     return error_mark_node;
6019
6020   rhstype = non_reference (rhstype);
6021
6022   type = complete_type (type);
6023
6024   if (IS_AGGR_TYPE (type))
6025     return ocp_convert (type, rhs, CONV_IMPLICIT|CONV_FORCE_TEMP, flags);
6026
6027   return convert_for_assignment (type, rhs, errtype, fndecl, parmnum);
6028 }
6029 \f
6030 /* If RETVAL is the address of, or a reference to, a local variable or
6031    temporary give an appropriate warning.  */
6032
6033 static void
6034 maybe_warn_about_returning_address_of_local (tree retval)
6035 {
6036   tree valtype = TREE_TYPE (DECL_RESULT (current_function_decl));
6037   tree whats_returned = retval;
6038
6039   for (;;)
6040     {
6041       if (TREE_CODE (whats_returned) == COMPOUND_EXPR)
6042         whats_returned = TREE_OPERAND (whats_returned, 1);
6043       else if (TREE_CODE (whats_returned) == CONVERT_EXPR
6044                || TREE_CODE (whats_returned) == NON_LVALUE_EXPR
6045                || TREE_CODE (whats_returned) == NOP_EXPR)
6046         whats_returned = TREE_OPERAND (whats_returned, 0);
6047       else
6048         break;
6049     }
6050
6051   if (TREE_CODE (whats_returned) != ADDR_EXPR)
6052     return;
6053   whats_returned = TREE_OPERAND (whats_returned, 0);
6054
6055   if (TREE_CODE (valtype) == REFERENCE_TYPE)
6056     {
6057       if (TREE_CODE (whats_returned) == AGGR_INIT_EXPR
6058           || TREE_CODE (whats_returned) == TARGET_EXPR)
6059         {
6060           warning ("returning reference to temporary");
6061           return;
6062         }
6063       if (TREE_CODE (whats_returned) == VAR_DECL
6064           && DECL_NAME (whats_returned)
6065           && TEMP_NAME_P (DECL_NAME (whats_returned)))
6066         {
6067           warning ("reference to non-lvalue returned");
6068           return;
6069         }
6070     }
6071
6072   if (DECL_P (whats_returned)
6073       && DECL_NAME (whats_returned)
6074       && DECL_FUNCTION_SCOPE_P (whats_returned)
6075       && !(TREE_STATIC (whats_returned)
6076            || TREE_PUBLIC (whats_returned)))
6077     {
6078       if (TREE_CODE (valtype) == REFERENCE_TYPE)
6079         cp_warning_at ("reference to local variable %qD returned",
6080                        whats_returned);
6081       else
6082         cp_warning_at ("address of local variable %qD returned",
6083                        whats_returned);
6084       return;
6085     }
6086 }
6087
6088 /* Check that returning RETVAL from the current function is valid.
6089    Return an expression explicitly showing all conversions required to
6090    change RETVAL into the function return type, and to assign it to
6091    the DECL_RESULT for the function.  */
6092
6093 tree
6094 check_return_expr (tree retval)
6095 {
6096   tree result;
6097   /* The type actually returned by the function, after any
6098      promotions.  */
6099   tree valtype;
6100   int fn_returns_value_p;
6101
6102   /* A `volatile' function is one that isn't supposed to return, ever.
6103      (This is a G++ extension, used to get better code for functions
6104      that call the `volatile' function.)  */
6105   if (TREE_THIS_VOLATILE (current_function_decl))
6106     warning ("function declared %<noreturn%> has a %<return%> statement");
6107
6108   /* Check for various simple errors.  */
6109   if (DECL_DESTRUCTOR_P (current_function_decl))
6110     {
6111       if (retval)
6112         error ("returning a value from a destructor");
6113       return NULL_TREE;
6114     }
6115   else if (DECL_CONSTRUCTOR_P (current_function_decl))
6116     {
6117       if (in_function_try_handler)
6118         /* If a return statement appears in a handler of the
6119            function-try-block of a constructor, the program is ill-formed.  */
6120         error ("cannot return from a handler of a function-try-block of a constructor");
6121       else if (retval)
6122         /* You can't return a value from a constructor.  */
6123         error ("returning a value from a constructor");
6124       return NULL_TREE;
6125     }
6126
6127   if (processing_template_decl)
6128     {
6129       current_function_returns_value = 1;
6130       return retval;
6131     }
6132
6133   /* When no explicit return-value is given in a function with a named
6134      return value, the named return value is used.  */
6135   result = DECL_RESULT (current_function_decl);
6136   valtype = TREE_TYPE (result);
6137   gcc_assert (valtype != NULL_TREE);
6138   fn_returns_value_p = !VOID_TYPE_P (valtype);
6139   if (!retval && DECL_NAME (result) && fn_returns_value_p)
6140     retval = result;
6141
6142   /* Check for a return statement with no return value in a function
6143      that's supposed to return a value.  */
6144   if (!retval && fn_returns_value_p)
6145     {
6146       pedwarn ("return-statement with no value, in function returning %qT",
6147                valtype);
6148       /* Clear this, so finish_function won't say that we reach the
6149          end of a non-void function (which we don't, we gave a
6150          return!).  */
6151       current_function_returns_null = 0;
6152     }
6153   /* Check for a return statement with a value in a function that
6154      isn't supposed to return a value.  */
6155   else if (retval && !fn_returns_value_p)
6156     {
6157       if (VOID_TYPE_P (TREE_TYPE (retval)))
6158         /* You can return a `void' value from a function of `void'
6159            type.  In that case, we have to evaluate the expression for
6160            its side-effects.  */
6161           finish_expr_stmt (retval);
6162       else
6163         pedwarn ("return-statement with a value, in function "
6164                  "returning 'void'");
6165
6166       current_function_returns_null = 1;
6167
6168       /* There's really no value to return, after all.  */
6169       return NULL_TREE;
6170     }
6171   else if (!retval)
6172     /* Remember that this function can sometimes return without a
6173        value.  */
6174     current_function_returns_null = 1;
6175   else
6176     /* Remember that this function did return a value.  */
6177     current_function_returns_value = 1;
6178
6179   /* Check for erroneous operands -- but after giving ourselves a
6180      chance to provide an error about returning a value from a void
6181      function.  */
6182   if (error_operand_p (retval))
6183     {
6184       current_function_return_value = error_mark_node;
6185       return error_mark_node;
6186     }
6187
6188   /* Only operator new(...) throw(), can return NULL [expr.new/13].  */
6189   if ((DECL_OVERLOADED_OPERATOR_P (current_function_decl) == NEW_EXPR
6190        || DECL_OVERLOADED_OPERATOR_P (current_function_decl) == VEC_NEW_EXPR)
6191       && !TYPE_NOTHROW_P (TREE_TYPE (current_function_decl))
6192       && ! flag_check_new
6193       && null_ptr_cst_p (retval))
6194     warning ("%<operator new%> must not return NULL unless it is "
6195              "declared %<throw()%> (or -fcheck-new is in effect)");
6196
6197   /* Effective C++ rule 15.  See also start_function.  */
6198   if (warn_ecpp
6199       && DECL_NAME (current_function_decl) == ansi_assopname(NOP_EXPR))
6200     {
6201       bool warn = true;
6202
6203       /* The function return type must be a reference to the current
6204         class.  */
6205       if (TREE_CODE (valtype) == REFERENCE_TYPE
6206           && same_type_ignoring_top_level_qualifiers_p
6207               (TREE_TYPE (valtype), TREE_TYPE (current_class_ref)))
6208         {
6209           /* Returning '*this' is obviously OK.  */
6210           if (retval == current_class_ref)
6211             warn = false;
6212           /* If we are calling a function whose return type is the same of
6213              the current class reference, it is ok.  */
6214           else if (TREE_CODE (retval) == INDIRECT_REF
6215                    && TREE_CODE (TREE_OPERAND (retval, 0)) == CALL_EXPR)
6216             warn = false;
6217         }
6218
6219       if (warn)
6220         warning ("%<operator=%> should return a reference to %<*this%>");
6221     }
6222
6223   /* The fabled Named Return Value optimization, as per [class.copy]/15:
6224
6225      [...]      For  a function with a class return type, if the expression
6226      in the return statement is the name of a local  object,  and  the  cv-
6227      unqualified  type  of  the  local  object  is the same as the function
6228      return type, an implementation is permitted to omit creating the  tem-
6229      porary  object  to  hold  the function return value [...]
6230
6231      So, if this is a value-returning function that always returns the same
6232      local variable, remember it.
6233
6234      It might be nice to be more flexible, and choose the first suitable
6235      variable even if the function sometimes returns something else, but
6236      then we run the risk of clobbering the variable we chose if the other
6237      returned expression uses the chosen variable somehow.  And people expect
6238      this restriction, anyway.  (jason 2000-11-19)
6239
6240      See finish_function and finalize_nrv for the rest of this optimization.  */
6241
6242   if (fn_returns_value_p && flag_elide_constructors)
6243     {
6244       if (retval != NULL_TREE
6245           && (current_function_return_value == NULL_TREE
6246               || current_function_return_value == retval)
6247           && TREE_CODE (retval) == VAR_DECL
6248           && DECL_CONTEXT (retval) == current_function_decl
6249           && ! TREE_STATIC (retval)
6250           && (DECL_ALIGN (retval)
6251               >= DECL_ALIGN (DECL_RESULT (current_function_decl)))
6252           && same_type_p ((TYPE_MAIN_VARIANT
6253                            (TREE_TYPE (retval))),
6254                           (TYPE_MAIN_VARIANT
6255                            (TREE_TYPE (TREE_TYPE (current_function_decl))))))
6256         current_function_return_value = retval;
6257       else
6258         current_function_return_value = error_mark_node;
6259     }
6260
6261   /* We don't need to do any conversions when there's nothing being
6262      returned.  */
6263   if (!retval)
6264     return NULL_TREE;
6265
6266   /* Do any required conversions.  */
6267   if (retval == result || DECL_CONSTRUCTOR_P (current_function_decl))
6268     /* No conversions are required.  */
6269     ;
6270   else
6271     {
6272       /* The type the function is declared to return.  */
6273       tree functype = TREE_TYPE (TREE_TYPE (current_function_decl));
6274
6275       /* First convert the value to the function's return type, then
6276          to the type of return value's location to handle the
6277          case that functype is smaller than the valtype.  */
6278       retval = convert_for_initialization
6279         (NULL_TREE, functype, retval, LOOKUP_NORMAL|LOOKUP_ONLYCONVERTING,
6280          "return", NULL_TREE, 0);
6281       retval = convert (valtype, retval);
6282
6283       /* If the conversion failed, treat this just like `return;'.  */
6284       if (retval == error_mark_node)
6285         return retval;
6286       /* We can't initialize a register from a AGGR_INIT_EXPR.  */
6287       else if (! current_function_returns_struct
6288                && TREE_CODE (retval) == TARGET_EXPR
6289                && TREE_CODE (TREE_OPERAND (retval, 1)) == AGGR_INIT_EXPR)
6290         retval = build2 (COMPOUND_EXPR, TREE_TYPE (retval), retval,
6291                          TREE_OPERAND (retval, 0));
6292       else
6293         maybe_warn_about_returning_address_of_local (retval);
6294     }
6295
6296   /* Actually copy the value returned into the appropriate location.  */
6297   if (retval && retval != result)
6298     retval = build2 (INIT_EXPR, TREE_TYPE (result), result, retval);
6299
6300   return retval;
6301 }
6302
6303 \f
6304 /* Returns nonzero if the pointer-type FROM can be converted to the
6305    pointer-type TO via a qualification conversion.  If CONSTP is -1,
6306    then we return nonzero if the pointers are similar, and the
6307    cv-qualification signature of FROM is a proper subset of that of TO.
6308
6309    If CONSTP is positive, then all outer pointers have been
6310    const-qualified.  */
6311
6312 static int
6313 comp_ptr_ttypes_real (tree to, tree from, int constp)
6314 {
6315   bool to_more_cv_qualified = false;
6316
6317   for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
6318     {
6319       if (TREE_CODE (to) != TREE_CODE (from))
6320         return 0;
6321
6322       if (TREE_CODE (from) == OFFSET_TYPE
6323           && !same_type_p (TYPE_OFFSET_BASETYPE (from),
6324                            TYPE_OFFSET_BASETYPE (to)))
6325         return 0;
6326
6327       /* Const and volatile mean something different for function types,
6328          so the usual checks are not appropriate.  */
6329       if (TREE_CODE (to) != FUNCTION_TYPE && TREE_CODE (to) != METHOD_TYPE)
6330         {
6331           if (!at_least_as_qualified_p (to, from))
6332             return 0;
6333
6334           if (!at_least_as_qualified_p (from, to))
6335             {
6336               if (constp == 0)
6337                 return 0;
6338               to_more_cv_qualified = true;
6339             }
6340
6341           if (constp > 0)
6342             constp &= TYPE_READONLY (to);
6343         }
6344
6345       if (TREE_CODE (to) != POINTER_TYPE && !TYPE_PTRMEM_P (to))
6346         return ((constp >= 0 || to_more_cv_qualified)
6347                 && same_type_ignoring_top_level_qualifiers_p (to, from));
6348     }
6349 }
6350
6351 /* When comparing, say, char ** to char const **, this function takes
6352    the 'char *' and 'char const *'.  Do not pass non-pointer/reference
6353    types to this function.  */
6354
6355 int
6356 comp_ptr_ttypes (tree to, tree from)
6357 {
6358   return comp_ptr_ttypes_real (to, from, 1);
6359 }
6360
6361 /* Returns 1 if to and from are (possibly multi-level) pointers to the same
6362    type or inheritance-related types, regardless of cv-quals.  */
6363
6364 int
6365 ptr_reasonably_similar (tree to, tree from)
6366 {
6367   for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
6368     {
6369       /* Any target type is similar enough to void.  */
6370       if (TREE_CODE (to) == VOID_TYPE
6371           || TREE_CODE (from) == VOID_TYPE)
6372         return 1;
6373
6374       if (TREE_CODE (to) != TREE_CODE (from))
6375         return 0;
6376
6377       if (TREE_CODE (from) == OFFSET_TYPE
6378           && comptypes (TYPE_OFFSET_BASETYPE (to),
6379                         TYPE_OFFSET_BASETYPE (from),
6380                         COMPARE_BASE | COMPARE_DERIVED))
6381         continue;
6382
6383       if (TREE_CODE (to) == VECTOR_TYPE
6384           && vector_types_convertible_p (to, from))
6385         return 1;
6386
6387       if (TREE_CODE (to) == INTEGER_TYPE
6388           && TYPE_PRECISION (to) == TYPE_PRECISION (from))
6389         return 1;
6390
6391       if (TREE_CODE (to) == FUNCTION_TYPE)
6392         return 1;
6393
6394       if (TREE_CODE (to) != POINTER_TYPE)
6395         return comptypes
6396           (TYPE_MAIN_VARIANT (to), TYPE_MAIN_VARIANT (from),
6397            COMPARE_BASE | COMPARE_DERIVED);
6398     }
6399 }
6400
6401 /* Like comp_ptr_ttypes, for const_cast.  */
6402
6403 static int
6404 comp_ptr_ttypes_const (tree to, tree from)
6405 {
6406   for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
6407     {
6408       if (TREE_CODE (to) != TREE_CODE (from))
6409         return 0;
6410
6411       if (TREE_CODE (from) == OFFSET_TYPE
6412           && same_type_p (TYPE_OFFSET_BASETYPE (from),
6413                           TYPE_OFFSET_BASETYPE (to)))
6414           continue;
6415
6416       if (TREE_CODE (to) != POINTER_TYPE)
6417         return same_type_ignoring_top_level_qualifiers_p (to, from);
6418     }
6419 }
6420
6421 /* Returns the type qualifiers for this type, including the qualifiers on the
6422    elements for an array type.  */
6423
6424 int
6425 cp_type_quals (tree type)
6426 {
6427   type = strip_array_types (type);
6428   if (type == error_mark_node)
6429     return TYPE_UNQUALIFIED;
6430   return TYPE_QUALS (type);
6431 }
6432
6433 /* Returns nonzero if the TYPE contains a mutable member.  */
6434
6435 bool
6436 cp_has_mutable_p (tree type)
6437 {
6438   type = strip_array_types (type);
6439
6440   return CLASS_TYPE_P (type) && CLASSTYPE_HAS_MUTABLE (type);
6441 }
6442
6443 /* Subroutine of casts_away_constness.  Make T1 and T2 point at
6444    exemplar types such that casting T1 to T2 is casting away constness
6445    if and only if there is no implicit conversion from T1 to T2.  */
6446
6447 static void
6448 casts_away_constness_r (tree *t1, tree *t2)
6449 {
6450   int quals1;
6451   int quals2;
6452
6453   /* [expr.const.cast]
6454
6455      For multi-level pointer to members and multi-level mixed pointers
6456      and pointers to members (conv.qual), the "member" aspect of a
6457      pointer to member level is ignored when determining if a const
6458      cv-qualifier has been cast away.  */
6459   if (TYPE_PTRMEM_P (*t1))
6460     *t1 = build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (*t1));
6461   if (TYPE_PTRMEM_P (*t2))
6462     *t2 = build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (*t2));
6463
6464   /* [expr.const.cast]
6465
6466      For  two  pointer types:
6467
6468             X1 is T1cv1,1 * ... cv1,N *   where T1 is not a pointer type
6469             X2 is T2cv2,1 * ... cv2,M *   where T2 is not a pointer type
6470             K is min(N,M)
6471
6472      casting from X1 to X2 casts away constness if, for a non-pointer
6473      type T there does not exist an implicit conversion (clause
6474      _conv_) from:
6475
6476             Tcv1,(N-K+1) * cv1,(N-K+2) * ... cv1,N *
6477
6478      to
6479
6480             Tcv2,(M-K+1) * cv2,(M-K+2) * ... cv2,M *.  */
6481
6482   if (TREE_CODE (*t1) != POINTER_TYPE
6483       || TREE_CODE (*t2) != POINTER_TYPE)
6484     {
6485       *t1 = cp_build_qualified_type (void_type_node,
6486                                      cp_type_quals (*t1));
6487       *t2 = cp_build_qualified_type (void_type_node,
6488                                      cp_type_quals (*t2));
6489       return;
6490     }
6491
6492   quals1 = cp_type_quals (*t1);
6493   quals2 = cp_type_quals (*t2);
6494   *t1 = TREE_TYPE (*t1);
6495   *t2 = TREE_TYPE (*t2);
6496   casts_away_constness_r (t1, t2);
6497   *t1 = build_pointer_type (*t1);
6498   *t2 = build_pointer_type (*t2);
6499   *t1 = cp_build_qualified_type (*t1, quals1);
6500   *t2 = cp_build_qualified_type (*t2, quals2);
6501 }
6502
6503 /* Returns nonzero if casting from TYPE1 to TYPE2 casts away
6504    constness.  */
6505
6506 static bool
6507 casts_away_constness (tree t1, tree t2)
6508 {
6509   if (TREE_CODE (t2) == REFERENCE_TYPE)
6510     {
6511       /* [expr.const.cast]
6512
6513          Casting from an lvalue of type T1 to an lvalue of type T2
6514          using a reference cast casts away constness if a cast from an
6515          rvalue of type "pointer to T1" to the type "pointer to T2"
6516          casts away constness.  */
6517       t1 = (TREE_CODE (t1) == REFERENCE_TYPE ? TREE_TYPE (t1) : t1);
6518       return casts_away_constness (build_pointer_type (t1),
6519                                    build_pointer_type (TREE_TYPE (t2)));
6520     }
6521
6522   if (TYPE_PTRMEM_P (t1) && TYPE_PTRMEM_P (t2))
6523     /* [expr.const.cast]
6524
6525        Casting from an rvalue of type "pointer to data member of X
6526        of type T1" to the type "pointer to data member of Y of type
6527        T2" casts away constness if a cast from an rvalue of type
6528        "pointer to T1" to the type "pointer to T2" casts away
6529        constness.  */
6530     return casts_away_constness
6531       (build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (t1)),
6532        build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (t2)));
6533
6534   /* Casting away constness is only something that makes sense for
6535      pointer or reference types.  */
6536   if (TREE_CODE (t1) != POINTER_TYPE
6537       || TREE_CODE (t2) != POINTER_TYPE)
6538     return false;
6539
6540   /* Top-level qualifiers don't matter.  */
6541   t1 = TYPE_MAIN_VARIANT (t1);
6542   t2 = TYPE_MAIN_VARIANT (t2);
6543   casts_away_constness_r (&t1, &t2);
6544   if (!can_convert (t2, t1))
6545     return true;
6546
6547   return false;
6548 }
6549
6550 /* If T is a REFERENCE_TYPE return the type to which T refers.
6551    Otherwise, return T itself.  */
6552
6553 tree
6554 non_reference (tree t)
6555 {
6556   if (TREE_CODE (t) == REFERENCE_TYPE)
6557     t = TREE_TYPE (t);
6558   return t;
6559 }