gcc/cp/typeck.c

   1 /* Build expressions with type checking for C++ compiler.
   2    Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
   4    Free Software Foundation, Inc.
   5    Hacked by Michael Tiemann (tiemann@cygnus.com)
   6
   7 This file is part of GCC.
   8
   9 GCC is free software; you can redistribute it and/or modify
  10 it under the terms of the GNU General Public License as published by
  11 the Free Software Foundation; either version 3, or (at your option)
  12 any later version.
  13
  14 GCC is distributed in the hope that it will be useful,
  15 but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 GNU General Public License for more details.
  18
  19 You should have received a copy of the GNU General Public License
  20 along with GCC; see the file COPYING3.  If not see
  21 <http://www.gnu.org/licenses/>.  */
  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 "intl.h"
  43 #include "target.h"
  44 #include "convert.h"
  45 #include "c-common.h"
  46 #include "params.h"
  47
  48 static tree pfn_from_ptrmemfunc (tree);
  49 static tree convert_for_assignment (tree, tree, const char *, tree, int);
  50 static tree cp_pointer_int_sum (enum tree_code, tree, tree);
  51 static tree rationalize_conditional_expr (enum tree_code, tree);
  52 static int comp_ptr_ttypes_real (tree, tree, int);
  53 static bool comp_except_types (tree, tree, bool);
  54 static bool comp_array_types (const_tree, const_tree, bool);
  55 static tree pointer_diff (tree, tree, tree);
  56 static tree get_delta_difference (tree, tree, bool, bool);
  57 static void casts_away_constness_r (tree *, tree *);
  58 static bool casts_away_constness (tree, tree);
  59 static void maybe_warn_about_returning_address_of_local (tree);
  60 static tree lookup_destructor (tree, tree, tree);
  61 static int convert_arguments (int, tree *, tree, tree, tree, int);
  62
  63 /* Do `exp = require_complete_type (exp);' to make sure exp
  64    does not have an incomplete type.  (That includes void types.)
  65    Returns the error_mark_node if the VALUE does not have
  66    complete type when this function returns.  */
  67
  68 tree
  69 require_complete_type (tree value)
  70 {
  71   tree type;
  72
  73   if (processing_template_decl || value == error_mark_node)
  74     return value;
  75
  76   if (TREE_CODE (value) == OVERLOAD)
  77     type = unknown_type_node;
  78   else
  79     type = TREE_TYPE (value);
  80
  81   if (type == error_mark_node)
  82     return error_mark_node;
  83
  84   /* First, detect a valid value with a complete type.  */
  85   if (COMPLETE_TYPE_P (type))
  86     return value;
  87
  88   if (complete_type_or_else (type, value))
  89     return value;
  90   else
  91     return error_mark_node;
  92 }
  93
  94 /* Try to complete TYPE, if it is incomplete.  For example, if TYPE is
  95    a template instantiation, do the instantiation.  Returns TYPE,
  96    whether or not it could be completed, unless something goes
  97    horribly wrong, in which case the error_mark_node is returned.  */
  98
  99 tree
 100 complete_type (tree type)
 101 {
 102   if (type == NULL_TREE)
 103     /* Rather than crash, we return something sure to cause an error
 104        at some point.  */
 105     return error_mark_node;
 106
 107   if (type == error_mark_node || COMPLETE_TYPE_P (type))
 108     ;
 109   else if (TREE_CODE (type) == ARRAY_TYPE && TYPE_DOMAIN (type))
 110     {
 111       tree t = complete_type (TREE_TYPE (type));
 112       unsigned int needs_constructing, has_nontrivial_dtor;
 113       if (COMPLETE_TYPE_P (t) && !dependent_type_p (type))
 114         layout_type (type);
 115       needs_constructing
 116         = TYPE_NEEDS_CONSTRUCTING (TYPE_MAIN_VARIANT (t));
 117       has_nontrivial_dtor
 118         = TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TYPE_MAIN_VARIANT (t));
 119       for (t = TYPE_MAIN_VARIANT (type); t; t = TYPE_NEXT_VARIANT (t))
 120         {
 121           TYPE_NEEDS_CONSTRUCTING (t) = needs_constructing;
 122           TYPE_HAS_NONTRIVIAL_DESTRUCTOR (t) = has_nontrivial_dtor;
 123         }
 124     }
 125   else if (CLASS_TYPE_P (type) && CLASSTYPE_TEMPLATE_INSTANTIATION (type))
 126     instantiate_class_template (TYPE_MAIN_VARIANT (type));
 127
 128   return type;
 129 }
 130
 131 /* Like complete_type, but issue an error if the TYPE cannot be completed.
 132    VALUE is used for informative diagnostics.
 133    Returns NULL_TREE if the type cannot be made complete.  */
 134
 135 tree
 136 complete_type_or_else (tree type, tree value)
 137 {
 138   type = complete_type (type);
 139   if (type == error_mark_node)
 140     /* We already issued an error.  */
 141     return NULL_TREE;
 142   else if (!COMPLETE_TYPE_P (type))
 143     {
 144       cxx_incomplete_type_diagnostic (value, type, 0);
 145       return NULL_TREE;
 146     }
 147   else
 148     return type;
 149 }
 150
 151 /* Return truthvalue of whether type of EXP is instantiated.  */
 152
 153 int
 154 type_unknown_p (const_tree exp)
 155 {
 156   return (TREE_CODE (exp) == TREE_LIST
 157           || TREE_TYPE (exp) == unknown_type_node);
 158 }
 159
 160 \f
 161 /* Return the common type of two parameter lists.
 162    We assume that comptypes has already been done and returned 1;
 163    if that isn't so, this may crash.
 164
 165    As an optimization, free the space we allocate if the parameter
 166    lists are already common.  */
 167
 168 static tree
 169 commonparms (tree p1, tree p2)
 170 {
 171   tree oldargs = p1, newargs, n;
 172   int i, len;
 173   int any_change = 0;
 174
 175   len = list_length (p1);
 176   newargs = tree_last (p1);
 177
 178   if (newargs == void_list_node)
 179     i = 1;
 180   else
 181     {
 182       i = 0;
 183       newargs = 0;
 184     }
 185
 186   for (; i < len; i++)
 187     newargs = tree_cons (NULL_TREE, NULL_TREE, newargs);
 188
 189   n = newargs;
 190
 191   for (i = 0; p1;
 192        p1 = TREE_CHAIN (p1), p2 = TREE_CHAIN (p2), n = TREE_CHAIN (n), i++)
 193     {
 194       if (TREE_PURPOSE (p1) && !TREE_PURPOSE (p2))
 195         {
 196           TREE_PURPOSE (n) = TREE_PURPOSE (p1);
 197           any_change = 1;
 198         }
 199       else if (! TREE_PURPOSE (p1))
 200         {
 201           if (TREE_PURPOSE (p2))
 202             {
 203               TREE_PURPOSE (n) = TREE_PURPOSE (p2);
 204               any_change = 1;
 205             }
 206         }
 207       else
 208         {
 209           if (1 != simple_cst_equal (TREE_PURPOSE (p1), TREE_PURPOSE (p2)))
 210             any_change = 1;
 211           TREE_PURPOSE (n) = TREE_PURPOSE (p2);
 212         }
 213       if (TREE_VALUE (p1) != TREE_VALUE (p2))
 214         {
 215           any_change = 1;
 216           TREE_VALUE (n) = merge_types (TREE_VALUE (p1), TREE_VALUE (p2));
 217         }
 218       else
 219         TREE_VALUE (n) = TREE_VALUE (p1);
 220     }
 221   if (! any_change)
 222     return oldargs;
 223
 224   return newargs;
 225 }
 226
 227 /* Given a type, perhaps copied for a typedef,
 228    find the "original" version of it.  */
 229 static tree
 230 original_type (tree t)
 231 {
 232   int quals = cp_type_quals (t);
 233   while (t != error_mark_node
 234          && TYPE_NAME (t) != NULL_TREE)
 235     {
 236       tree x = TYPE_NAME (t);
 237       if (TREE_CODE (x) != TYPE_DECL)
 238         break;
 239       x = DECL_ORIGINAL_TYPE (x);
 240       if (x == NULL_TREE)
 241         break;
 242       t = x;
 243     }
 244   return cp_build_qualified_type (t, quals);
 245 }
 246
 247 /* T1 and T2 are arithmetic or enumeration types.  Return the type
 248    that will result from the "usual arithmetic conversions" on T1 and
 249    T2 as described in [expr].  */
 250
 251 tree
 252 type_after_usual_arithmetic_conversions (tree t1, tree t2)
 253 {
 254   enum tree_code code1 = TREE_CODE (t1);
 255   enum tree_code code2 = TREE_CODE (t2);
 256   tree attributes;
 257
 258   /* FIXME: Attributes.  */
 259   gcc_assert (ARITHMETIC_TYPE_P (t1)
 260               || TREE_CODE (t1) == VECTOR_TYPE
 261               || TREE_CODE (t1) == ENUMERAL_TYPE);
 262   gcc_assert (ARITHMETIC_TYPE_P (t2)
 263               || TREE_CODE (t2) == VECTOR_TYPE
 264               || TREE_CODE (t2) == ENUMERAL_TYPE);
 265
 266   /* In what follows, we slightly generalize the rules given in [expr] so
 267      as to deal with `long long' and `complex'.  First, merge the
 268      attributes.  */
 269   attributes = (*targetm.merge_type_attributes) (t1, t2);
 270
 271   /* If one type is complex, form the common type of the non-complex
 272      components, then make that complex.  Use T1 or T2 if it is the
 273      required type.  */
 274   if (code1 == COMPLEX_TYPE || code2 == COMPLEX_TYPE)
 275     {
 276       tree subtype1 = code1 == COMPLEX_TYPE ? TREE_TYPE (t1) : t1;
 277       tree subtype2 = code2 == COMPLEX_TYPE ? TREE_TYPE (t2) : t2;
 278       tree subtype
 279         = type_after_usual_arithmetic_conversions (subtype1, subtype2);
 280
 281       if (code1 == COMPLEX_TYPE && TREE_TYPE (t1) == subtype)
 282         return build_type_attribute_variant (t1, attributes);
 283       else if (code2 == COMPLEX_TYPE && TREE_TYPE (t2) == subtype)
 284         return build_type_attribute_variant (t2, attributes);
 285       else
 286         return build_type_attribute_variant (build_complex_type (subtype),
 287                                              attributes);
 288     }
 289
 290   if (code1 == VECTOR_TYPE)
 291     {
 292       /* When we get here we should have two vectors of the same size.
 293          Just prefer the unsigned one if present.  */
 294       if (TYPE_UNSIGNED (t1))
 295         return build_type_attribute_variant (t1, attributes);
 296       else
 297         return build_type_attribute_variant (t2, attributes);
 298     }
 299
 300   /* If only one is real, use it as the result.  */
 301   if (code1 == REAL_TYPE && code2 != REAL_TYPE)
 302     return build_type_attribute_variant (t1, attributes);
 303   if (code2 == REAL_TYPE && code1 != REAL_TYPE)
 304     return build_type_attribute_variant (t2, attributes);
 305
 306   /* Perform the integral promotions.  */
 307   if (code1 != REAL_TYPE)
 308     {
 309       t1 = type_promotes_to (t1);
 310       t2 = type_promotes_to (t2);
 311     }
 312
 313   /* Both real or both integers; use the one with greater precision.  */
 314   if (TYPE_PRECISION (t1) > TYPE_PRECISION (t2))
 315     return build_type_attribute_variant (t1, attributes);
 316   else if (TYPE_PRECISION (t2) > TYPE_PRECISION (t1))
 317     return build_type_attribute_variant (t2, attributes);
 318
 319   /* The types are the same; no need to do anything fancy.  */
 320   if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
 321     return build_type_attribute_variant (t1, attributes);
 322
 323   if (code1 != REAL_TYPE)
 324     {
 325       /* If one is unsigned long long, then convert the other to unsigned
 326          long long.  */
 327       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_long_unsigned_type_node)
 328           || same_type_p (TYPE_MAIN_VARIANT (t2), long_long_unsigned_type_node))
 329         return build_type_attribute_variant (long_long_unsigned_type_node,
 330                                              attributes);
 331       /* If one is a long long, and the other is an unsigned long, and
 332          long long can represent all the values of an unsigned long, then
 333          convert to a long long.  Otherwise, convert to an unsigned long
 334          long.  Otherwise, if either operand is long long, convert the
 335          other to long long.
 336
 337          Since we're here, we know the TYPE_PRECISION is the same;
 338          therefore converting to long long cannot represent all the values
 339          of an unsigned long, so we choose unsigned long long in that
 340          case.  */
 341       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_long_integer_type_node)
 342           || same_type_p (TYPE_MAIN_VARIANT (t2), long_long_integer_type_node))
 343         {
 344           tree t = ((TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 345                     ? long_long_unsigned_type_node
 346                     : long_long_integer_type_node);
 347           return build_type_attribute_variant (t, attributes);
 348         }
 349
 350       /* Go through the same procedure, but for longs.  */
 351       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_unsigned_type_node)
 352           || same_type_p (TYPE_MAIN_VARIANT (t2), long_unsigned_type_node))
 353         return build_type_attribute_variant (long_unsigned_type_node,
 354                                              attributes);
 355       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_integer_type_node)
 356           || same_type_p (TYPE_MAIN_VARIANT (t2), long_integer_type_node))
 357         {
 358           tree t = ((TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 359                     ? long_unsigned_type_node : long_integer_type_node);
 360           return build_type_attribute_variant (t, attributes);
 361         }
 362       /* Otherwise prefer the unsigned one.  */
 363       if (TYPE_UNSIGNED (t1))
 364         return build_type_attribute_variant (t1, attributes);
 365       else
 366         return build_type_attribute_variant (t2, attributes);
 367     }
 368   else
 369     {
 370       if (same_type_p (TYPE_MAIN_VARIANT (t1), long_double_type_node)
 371           || same_type_p (TYPE_MAIN_VARIANT (t2), long_double_type_node))
 372         return build_type_attribute_variant (long_double_type_node,
 373                                              attributes);
 374       if (same_type_p (TYPE_MAIN_VARIANT (t1), double_type_node)
 375           || same_type_p (TYPE_MAIN_VARIANT (t2), double_type_node))
 376         return build_type_attribute_variant (double_type_node,
 377                                              attributes);
 378       if (same_type_p (TYPE_MAIN_VARIANT (t1), float_type_node)
 379           || same_type_p (TYPE_MAIN_VARIANT (t2), float_type_node))
 380         return build_type_attribute_variant (float_type_node,
 381                                              attributes);
 382
 383       /* Two floating-point types whose TYPE_MAIN_VARIANTs are none of
 384          the standard C++ floating-point types.  Logic earlier in this
 385          function has already eliminated the possibility that
 386          TYPE_PRECISION (t2) != TYPE_PRECISION (t1), so there's no
 387          compelling reason to choose one or the other.  */
 388       return build_type_attribute_variant (t1, attributes);
 389     }
 390 }
 391
 392 /* Subroutine of composite_pointer_type to implement the recursive
 393    case.  See that function for documentation fo the parameters.  */
 394
 395 static tree
 396 composite_pointer_type_r (tree t1, tree t2, const char* location)
 397 {
 398   tree pointee1;
 399   tree pointee2;
 400   tree result_type;
 401   tree attributes;
 402
 403   /* Determine the types pointed to by T1 and T2.  */
 404   if (TREE_CODE (t1) == POINTER_TYPE)
 405     {
 406       pointee1 = TREE_TYPE (t1);
 407       pointee2 = TREE_TYPE (t2);
 408     }
 409   else
 410     {
 411       pointee1 = TYPE_PTRMEM_POINTED_TO_TYPE (t1);
 412       pointee2 = TYPE_PTRMEM_POINTED_TO_TYPE (t2);
 413     }
 414
 415   /* [expr.rel]
 416
 417      Otherwise, the composite pointer type is a pointer type
 418      similar (_conv.qual_) to the type of one of the operands,
 419      with a cv-qualification signature (_conv.qual_) that is the
 420      union of the cv-qualification signatures of the operand
 421      types.  */
 422   if (same_type_ignoring_top_level_qualifiers_p (pointee1, pointee2))
 423     result_type = pointee1;
 424   else if ((TREE_CODE (pointee1) == POINTER_TYPE
 425             && TREE_CODE (pointee2) == POINTER_TYPE)
 426            || (TYPE_PTR_TO_MEMBER_P (pointee1)
 427                && TYPE_PTR_TO_MEMBER_P (pointee2)))
 428     result_type = composite_pointer_type_r (pointee1, pointee2, location);
 429   else
 430     {
 431       pedwarn ("%s between distinct pointer types %qT and %qT "
 432                "lacks a cast",
 433                location, t1, t2);
 434       result_type = void_type_node;
 435     }
 436   result_type = cp_build_qualified_type (result_type,
 437                                          (cp_type_quals (pointee1)
 438                                           | cp_type_quals (pointee2)));
 439   /* If the original types were pointers to members, so is the
 440      result.  */
 441   if (TYPE_PTR_TO_MEMBER_P (t1))
 442     {
 443       if (!same_type_p (TYPE_PTRMEM_CLASS_TYPE (t1),
 444                         TYPE_PTRMEM_CLASS_TYPE (t2)))
 445         pedwarn ("%s between distinct pointer types %qT and %qT "
 446                  "lacks a cast",
 447                  location, t1, t2);
 448       result_type = build_ptrmem_type (TYPE_PTRMEM_CLASS_TYPE (t1),
 449                                        result_type);
 450     }
 451   else
 452     result_type = build_pointer_type (result_type);
 453
 454   /* Merge the attributes.  */
 455   attributes = (*targetm.merge_type_attributes) (t1, t2);
 456   return build_type_attribute_variant (result_type, attributes);
 457 }
 458
 459 /* Return the composite pointer type (see [expr.rel]) for T1 and T2.
 460    ARG1 and ARG2 are the values with those types.  The LOCATION is a
 461    string describing the current location, in case an error occurs.
 462
 463    This routine also implements the computation of a common type for
 464    pointers-to-members as per [expr.eq].  */
 465
 466 tree
 467 composite_pointer_type (tree t1, tree t2, tree arg1, tree arg2,
 468                         const char* location)
 469 {
 470   tree class1;
 471   tree class2;
 472
 473   /* [expr.rel]
 474
 475      If one operand is a null pointer constant, the composite pointer
 476      type is the type of the other operand.  */
 477   if (null_ptr_cst_p (arg1))
 478     return t2;
 479   if (null_ptr_cst_p (arg2))
 480     return t1;
 481
 482   /* We have:
 483
 484        [expr.rel]
 485
 486        If one of the operands has type "pointer to cv1 void*", then
 487        the other has type "pointer to cv2T", and the composite pointer
 488        type is "pointer to cv12 void", where cv12 is the union of cv1
 489        and cv2.
 490
 491     If either type is a pointer to void, make sure it is T1.  */
 492   if (TREE_CODE (t2) == POINTER_TYPE && VOID_TYPE_P (TREE_TYPE (t2)))
 493     {
 494       tree t;
 495       t = t1;
 496       t1 = t2;
 497       t2 = t;
 498     }
 499
 500   /* Now, if T1 is a pointer to void, merge the qualifiers.  */
 501   if (TREE_CODE (t1) == POINTER_TYPE && VOID_TYPE_P (TREE_TYPE (t1)))
 502     {
 503       tree attributes;
 504       tree result_type;
 505
 506       if (pedantic && TYPE_PTRFN_P (t2))
 507         pedwarn ("ISO C++ forbids %s between pointer of type %<void *%> "
 508                  "and pointer-to-function", location);
 509       result_type
 510         = cp_build_qualified_type (void_type_node,
 511                                    (cp_type_quals (TREE_TYPE (t1))
 512                                     | cp_type_quals (TREE_TYPE (t2))));
 513       result_type = build_pointer_type (result_type);
 514       /* Merge the attributes.  */
 515       attributes = (*targetm.merge_type_attributes) (t1, t2);
 516       return build_type_attribute_variant (result_type, attributes);
 517     }
 518
 519   if (c_dialect_objc () && TREE_CODE (t1) == POINTER_TYPE
 520       && TREE_CODE (t2) == POINTER_TYPE)
 521     {
 522       if (objc_compare_types (t1, t2, -3, NULL_TREE))
 523         return t1;
 524     }
 525
 526   /* [expr.eq] permits the application of a pointer conversion to
 527      bring the pointers to a common type.  */
 528   if (TREE_CODE (t1) == POINTER_TYPE && TREE_CODE (t2) == POINTER_TYPE
 529       && CLASS_TYPE_P (TREE_TYPE (t1))
 530       && CLASS_TYPE_P (TREE_TYPE (t2))
 531       && !same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (t1),
 532                                                      TREE_TYPE (t2)))
 533     {
 534       class1 = TREE_TYPE (t1);
 535       class2 = TREE_TYPE (t2);
 536
 537       if (DERIVED_FROM_P (class1, class2))
 538         t2 = (build_pointer_type
 539               (cp_build_qualified_type (class1, TYPE_QUALS (class2))));
 540       else if (DERIVED_FROM_P (class2, class1))
 541         t1 = (build_pointer_type
 542               (cp_build_qualified_type (class2, TYPE_QUALS (class1))));
 543       else
 544         {
 545           error ("%s between distinct pointer types %qT and %qT "
 546                  "lacks a cast", location, t1, t2);
 547           return error_mark_node;
 548         }
 549     }
 550   /* [expr.eq] permits the application of a pointer-to-member
 551      conversion to change the class type of one of the types.  */
 552   else if (TYPE_PTR_TO_MEMBER_P (t1)
 553            && !same_type_p (TYPE_PTRMEM_CLASS_TYPE (t1),
 554                             TYPE_PTRMEM_CLASS_TYPE (t2)))
 555     {
 556       class1 = TYPE_PTRMEM_CLASS_TYPE (t1);
 557       class2 = TYPE_PTRMEM_CLASS_TYPE (t2);
 558
 559       if (DERIVED_FROM_P (class1, class2))
 560         t1 = build_ptrmem_type (class2, TYPE_PTRMEM_POINTED_TO_TYPE (t1));
 561       else if (DERIVED_FROM_P (class2, class1))
 562         t2 = build_ptrmem_type (class1, TYPE_PTRMEM_POINTED_TO_TYPE (t2));
 563       else
 564         {
 565           error ("%s between distinct pointer-to-member types %qT and %qT "
 566                  "lacks a cast", location, t1, t2);
 567           return error_mark_node;
 568         }
 569     }
 570
 571   return composite_pointer_type_r (t1, t2, location);
 572 }
 573
 574 /* Return the merged type of two types.
 575    We assume that comptypes has already been done and returned 1;
 576    if that isn't so, this may crash.
 577
 578    This just combines attributes and default arguments; any other
 579    differences would cause the two types to compare unalike.  */
 580
 581 tree
 582 merge_types (tree t1, tree t2)
 583 {
 584   enum tree_code code1;
 585   enum tree_code code2;
 586   tree attributes;
 587
 588   /* Save time if the two types are the same.  */
 589   if (t1 == t2)
 590     return t1;
 591   if (original_type (t1) == original_type (t2))
 592     return t1;
 593
 594   /* If one type is nonsense, use the other.  */
 595   if (t1 == error_mark_node)
 596     return t2;
 597   if (t2 == error_mark_node)
 598     return t1;
 599
 600   /* Merge the attributes.  */
 601   attributes = (*targetm.merge_type_attributes) (t1, t2);
 602
 603   if (TYPE_PTRMEMFUNC_P (t1))
 604     t1 = TYPE_PTRMEMFUNC_FN_TYPE (t1);
 605   if (TYPE_PTRMEMFUNC_P (t2))
 606     t2 = TYPE_PTRMEMFUNC_FN_TYPE (t2);
 607
 608   code1 = TREE_CODE (t1);
 609   code2 = TREE_CODE (t2);
 610
 611   switch (code1)
 612     {
 613     case POINTER_TYPE:
 614     case REFERENCE_TYPE:
 615       /* For two pointers, do this recursively on the target type.  */
 616       {
 617         tree target = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
 618         int quals = cp_type_quals (t1);
 619
 620         if (code1 == POINTER_TYPE)
 621           t1 = build_pointer_type (target);
 622         else
 623           t1 = build_reference_type (target);
 624         t1 = build_type_attribute_variant (t1, attributes);
 625         t1 = cp_build_qualified_type (t1, quals);
 626
 627         if (TREE_CODE (target) == METHOD_TYPE)
 628           t1 = build_ptrmemfunc_type (t1);
 629
 630         return t1;
 631       }
 632
 633     case OFFSET_TYPE:
 634       {
 635         int quals;
 636         tree pointee;
 637         quals = cp_type_quals (t1);
 638         pointee = merge_types (TYPE_PTRMEM_POINTED_TO_TYPE (t1),
 639                                TYPE_PTRMEM_POINTED_TO_TYPE (t2));
 640         t1 = build_ptrmem_type (TYPE_PTRMEM_CLASS_TYPE (t1),
 641                                 pointee);
 642         t1 = cp_build_qualified_type (t1, quals);
 643         break;
 644       }
 645
 646     case ARRAY_TYPE:
 647       {
 648         tree elt = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
 649         /* Save space: see if the result is identical to one of the args.  */
 650         if (elt == TREE_TYPE (t1) && TYPE_DOMAIN (t1))
 651           return build_type_attribute_variant (t1, attributes);
 652         if (elt == TREE_TYPE (t2) && TYPE_DOMAIN (t2))
 653           return build_type_attribute_variant (t2, attributes);
 654         /* Merge the element types, and have a size if either arg has one.  */
 655         t1 = build_cplus_array_type
 656           (elt, TYPE_DOMAIN (TYPE_DOMAIN (t1) ? t1 : t2));
 657         break;
 658       }
 659
 660     case FUNCTION_TYPE:
 661       /* Function types: prefer the one that specified arg types.
 662          If both do, merge the arg types.  Also merge the return types.  */
 663       {
 664         tree valtype = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
 665         tree p1 = TYPE_ARG_TYPES (t1);
 666         tree p2 = TYPE_ARG_TYPES (t2);
 667         tree rval, raises;
 668
 669         /* Save space: see if the result is identical to one of the args.  */
 670         if (valtype == TREE_TYPE (t1) && ! p2)
 671           return cp_build_type_attribute_variant (t1, attributes);
 672         if (valtype == TREE_TYPE (t2) && ! p1)
 673           return cp_build_type_attribute_variant (t2, attributes);
 674
 675         /* Simple way if one arg fails to specify argument types.  */
 676         if (p1 == NULL_TREE || TREE_VALUE (p1) == void_type_node)
 677           {
 678             rval = build_function_type (valtype, p2);
 679             if ((raises = TYPE_RAISES_EXCEPTIONS (t2)))
 680               rval = build_exception_variant (rval, raises);
 681             return cp_build_type_attribute_variant (rval, attributes);
 682           }
 683         raises = TYPE_RAISES_EXCEPTIONS (t1);
 684         if (p2 == NULL_TREE || TREE_VALUE (p2) == void_type_node)
 685           {
 686             rval = build_function_type (valtype, p1);
 687             if (raises)
 688               rval = build_exception_variant (rval, raises);
 689             return cp_build_type_attribute_variant (rval, attributes);
 690           }
 691
 692         rval = build_function_type (valtype, commonparms (p1, p2));
 693         t1 = build_exception_variant (rval, raises);
 694         break;
 695       }
 696
 697     case METHOD_TYPE:
 698       {
 699         /* Get this value the long way, since TYPE_METHOD_BASETYPE
 700            is just the main variant of this.  */
 701         tree basetype = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (t2)));
 702         tree raises = TYPE_RAISES_EXCEPTIONS (t1);
 703         tree t3;
 704
 705         /* If this was a member function type, get back to the
 706            original type of type member function (i.e., without
 707            the class instance variable up front.  */
 708         t1 = build_function_type (TREE_TYPE (t1),
 709                                   TREE_CHAIN (TYPE_ARG_TYPES (t1)));
 710         t2 = build_function_type (TREE_TYPE (t2),
 711                                   TREE_CHAIN (TYPE_ARG_TYPES (t2)));
 712         t3 = merge_types (t1, t2);
 713         t3 = build_method_type_directly (basetype, TREE_TYPE (t3),
 714                                          TYPE_ARG_TYPES (t3));
 715         t1 = build_exception_variant (t3, raises);
 716         break;
 717       }
 718
 719     case TYPENAME_TYPE:
 720       /* There is no need to merge attributes into a TYPENAME_TYPE.
 721          When the type is instantiated it will have whatever
 722          attributes result from the instantiation.  */
 723       return t1;
 724
 725     default:;
 726     }
 727
 728   if (attribute_list_equal (TYPE_ATTRIBUTES (t1), attributes))
 729     return t1;
 730   else if (attribute_list_equal (TYPE_ATTRIBUTES (t2), attributes))
 731     return t2;
 732   else
 733     return cp_build_type_attribute_variant (t1, attributes);
 734 }
 735
 736 /* Return the common type of two types.
 737    We assume that comptypes has already been done and returned 1;
 738    if that isn't so, this may crash.
 739
 740    This is the type for the result of most arithmetic operations
 741    if the operands have the given two types.  */
 742
 743 tree
 744 common_type (tree t1, tree t2)
 745 {
 746   enum tree_code code1;
 747   enum tree_code code2;
 748
 749   /* If one type is nonsense, bail.  */
 750   if (t1 == error_mark_node || t2 == error_mark_node)
 751     return error_mark_node;
 752
 753   code1 = TREE_CODE (t1);
 754   code2 = TREE_CODE (t2);
 755
 756   if ((ARITHMETIC_TYPE_P (t1) || code1 == ENUMERAL_TYPE
 757        || code1 == VECTOR_TYPE)
 758       && (ARITHMETIC_TYPE_P (t2) || code2 == ENUMERAL_TYPE
 759           || code2 == VECTOR_TYPE))
 760     return type_after_usual_arithmetic_conversions (t1, t2);
 761
 762   else if ((TYPE_PTR_P (t1) && TYPE_PTR_P (t2))
 763            || (TYPE_PTRMEM_P (t1) && TYPE_PTRMEM_P (t2))
 764            || (TYPE_PTRMEMFUNC_P (t1) && TYPE_PTRMEMFUNC_P (t2)))
 765     return composite_pointer_type (t1, t2, error_mark_node, error_mark_node,
 766                                    "conversion");
 767   else
 768     gcc_unreachable ();
 769 }
 770 \f
 771 /* Compare two exception specifier types for exactness or subsetness, if
 772    allowed. Returns false for mismatch, true for match (same, or
 773    derived and !exact).
 774
 775    [except.spec] "If a class X ... objects of class X or any class publicly
 776    and unambiguously derived from X. Similarly, if a pointer type Y * ...
 777    exceptions of type Y * or that are pointers to any type publicly and
 778    unambiguously derived from Y. Otherwise a function only allows exceptions
 779    that have the same type ..."
 780    This does not mention cv qualifiers and is different to what throw
 781    [except.throw] and catch [except.catch] will do. They will ignore the
 782    top level cv qualifiers, and allow qualifiers in the pointer to class
 783    example.
 784
 785    We implement the letter of the standard.  */
 786
 787 static bool
 788 comp_except_types (tree a, tree b, bool exact)
 789 {
 790   if (same_type_p (a, b))
 791     return true;
 792   else if (!exact)
 793     {
 794       if (cp_type_quals (a) || cp_type_quals (b))
 795         return false;
 796
 797       if (TREE_CODE (a) == POINTER_TYPE
 798           && TREE_CODE (b) == POINTER_TYPE)
 799         {
 800           a = TREE_TYPE (a);
 801           b = TREE_TYPE (b);
 802           if (cp_type_quals (a) || cp_type_quals (b))
 803             return false;
 804         }
 805
 806       if (TREE_CODE (a) != RECORD_TYPE
 807           || TREE_CODE (b) != RECORD_TYPE)
 808         return false;
 809
 810       if (PUBLICLY_UNIQUELY_DERIVED_P (a, b))
 811         return true;
 812     }
 813   return false;
 814 }
 815
 816 /* Return true if TYPE1 and TYPE2 are equivalent exception specifiers.
 817    If EXACT is false, T2 can be stricter than T1 (according to 15.4/7),
 818    otherwise it must be exact. Exception lists are unordered, but
 819    we've already filtered out duplicates. Most lists will be in order,
 820    we should try to make use of that.  */
 821
 822 bool
 823 comp_except_specs (const_tree t1, const_tree t2, bool exact)
 824 {
 825   const_tree probe;
 826   const_tree base;
 827   int  length = 0;
 828
 829   if (t1 == t2)
 830     return true;
 831
 832   if (t1 == NULL_TREE)                     /* T1 is ...  */
 833     return t2 == NULL_TREE || !exact;
 834   if (!TREE_VALUE (t1))                    /* t1 is EMPTY */
 835     return t2 != NULL_TREE && !TREE_VALUE (t2);
 836   if (t2 == NULL_TREE)                     /* T2 is ...  */
 837     return false;
 838   if (TREE_VALUE (t1) && !TREE_VALUE (t2)) /* T2 is EMPTY, T1 is not */
 839     return !exact;
 840
 841   /* Neither set is ... or EMPTY, make sure each part of T2 is in T1.
 842      Count how many we find, to determine exactness. For exact matching and
 843      ordered T1, T2, this is an O(n) operation, otherwise its worst case is
 844      O(nm).  */
 845   for (base = t1; t2 != NULL_TREE; t2 = TREE_CHAIN (t2))
 846     {
 847       for (probe = base; probe != NULL_TREE; probe = TREE_CHAIN (probe))
 848         {
 849           tree a = TREE_VALUE (probe);
 850           tree b = TREE_VALUE (t2);
 851
 852           if (comp_except_types (a, b, exact))
 853             {
 854               if (probe == base && exact)
 855                 base = TREE_CHAIN (probe);
 856               length++;
 857               break;
 858             }
 859         }
 860       if (probe == NULL_TREE)
 861         return false;
 862     }
 863   return !exact || base == NULL_TREE || length == list_length (t1);
 864 }
 865
 866 /* Compare the array types T1 and T2.  ALLOW_REDECLARATION is true if
 867    [] can match [size].  */
 868
 869 static bool
 870 comp_array_types (const_tree t1, const_tree t2, bool allow_redeclaration)
 871 {
 872   tree d1;
 873   tree d2;
 874   tree max1, max2;
 875
 876   if (t1 == t2)
 877     return true;
 878
 879   /* The type of the array elements must be the same.  */
 880   if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
 881     return false;
 882
 883   d1 = TYPE_DOMAIN (t1);
 884   d2 = TYPE_DOMAIN (t2);
 885
 886   if (d1 == d2)
 887     return true;
 888
 889   /* If one of the arrays is dimensionless, and the other has a
 890      dimension, they are of different types.  However, it is valid to
 891      write:
 892
 893        extern int a[];
 894        int a[3];
 895
 896      by [basic.link]:
 897
 898        declarations for an array object can specify
 899        array types that differ by the presence or absence of a major
 900        array bound (_dcl.array_).  */
 901   if (!d1 || !d2)
 902     return allow_redeclaration;
 903
 904   /* Check that the dimensions are the same.  */
 905
 906   if (!cp_tree_equal (TYPE_MIN_VALUE (d1), TYPE_MIN_VALUE (d2)))
 907     return false;
 908   max1 = TYPE_MAX_VALUE (d1);
 909   max2 = TYPE_MAX_VALUE (d2);
 910   if (processing_template_decl && !abi_version_at_least (2)
 911       && !value_dependent_expression_p (max1)
 912       && !value_dependent_expression_p (max2))
 913     {
 914       /* With abi-1 we do not fold non-dependent array bounds, (and
 915          consequently mangle them incorrectly).  We must therefore
 916          fold them here, to verify the domains have the same
 917          value.  */
 918       max1 = fold (max1);
 919       max2 = fold (max2);
 920     }
 921
 922   if (!cp_tree_equal (max1, max2))
 923     return false;
 924
 925   return true;
 926 }
 927
 928 /* Subroutine in comptypes.  */
 929
 930 static bool
 931 structural_comptypes (tree t1, tree t2, int strict)
 932 {
 933   if (t1 == t2)
 934     return true;
 935
 936   /* Suppress errors caused by previously reported errors.  */
 937   if (t1 == error_mark_node || t2 == error_mark_node)
 938     return false;
 939
 940   gcc_assert (TYPE_P (t1) && TYPE_P (t2));
 941
 942   /* TYPENAME_TYPEs should be resolved if the qualifying scope is the
 943      current instantiation.  */
 944   if (TREE_CODE (t1) == TYPENAME_TYPE)
 945     t1 = resolve_typename_type (t1, /*only_current_p=*/true);
 946
 947   if (TREE_CODE (t2) == TYPENAME_TYPE)
 948     t2 = resolve_typename_type (t2, /*only_current_p=*/true);
 949
 950   if (TYPE_PTRMEMFUNC_P (t1))
 951     t1 = TYPE_PTRMEMFUNC_FN_TYPE (t1);
 952   if (TYPE_PTRMEMFUNC_P (t2))
 953     t2 = TYPE_PTRMEMFUNC_FN_TYPE (t2);
 954
 955   /* Different classes of types can't be compatible.  */
 956   if (TREE_CODE (t1) != TREE_CODE (t2))
 957     return false;
 958
 959   /* Qualifiers must match.  For array types, we will check when we
 960      recur on the array element types.  */
 961   if (TREE_CODE (t1) != ARRAY_TYPE
 962       && TYPE_QUALS (t1) != TYPE_QUALS (t2))
 963     return false;
 964   if (TYPE_FOR_JAVA (t1) != TYPE_FOR_JAVA (t2))
 965     return false;
 966
 967   /* Allow for two different type nodes which have essentially the same
 968      definition.  Note that we already checked for equality of the type
 969      qualifiers (just above).  */
 970
 971   if (TREE_CODE (t1) != ARRAY_TYPE
 972       && TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
 973     return true;
 974
 975   /* Compare the types.  Break out if they could be the same.  */
 976   switch (TREE_CODE (t1))
 977     {
 978     case TEMPLATE_TEMPLATE_PARM:
 979     case BOUND_TEMPLATE_TEMPLATE_PARM:
 980       if (TEMPLATE_TYPE_IDX (t1) != TEMPLATE_TYPE_IDX (t2)
 981           || TEMPLATE_TYPE_LEVEL (t1) != TEMPLATE_TYPE_LEVEL (t2)
 982           || (TEMPLATE_TYPE_PARAMETER_PACK (t1)
 983               != TEMPLATE_TYPE_PARAMETER_PACK (t2)))
 984         return false;
 985       if (!comp_template_parms
 986           (DECL_TEMPLATE_PARMS (TEMPLATE_TEMPLATE_PARM_TEMPLATE_DECL (t1)),
 987            DECL_TEMPLATE_PARMS (TEMPLATE_TEMPLATE_PARM_TEMPLATE_DECL (t2))))
 988         return false;
 989       if (TREE_CODE (t1) == TEMPLATE_TEMPLATE_PARM)
 990         break;
 991       /* Don't check inheritance.  */
 992       strict = COMPARE_STRICT;
 993       /* Fall through.  */
 994
 995     case RECORD_TYPE:
 996     case UNION_TYPE:
 997       if (TYPE_TEMPLATE_INFO (t1) && TYPE_TEMPLATE_INFO (t2)
 998           && (TYPE_TI_TEMPLATE (t1) == TYPE_TI_TEMPLATE (t2)
 999               || TREE_CODE (t1) == BOUND_TEMPLATE_TEMPLATE_PARM)
1000           && comp_template_args (TYPE_TI_ARGS (t1), TYPE_TI_ARGS (t2)))
1001         break;
1002
1003       if ((strict & COMPARE_BASE) && DERIVED_FROM_P (t1, t2))
1004         break;
1005       else if ((strict & COMPARE_DERIVED) && DERIVED_FROM_P (t2, t1))
1006         break;
1007
1008       return false;
1009
1010     case OFFSET_TYPE:
1011       if (!comptypes (TYPE_OFFSET_BASETYPE (t1), TYPE_OFFSET_BASETYPE (t2),
1012                       strict & ~COMPARE_REDECLARATION))
1013         return false;
1014       if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
1015         return false;
1016       break;
1017
1018     case REFERENCE_TYPE:
1019       if (TYPE_REF_IS_RVALUE (t1) != TYPE_REF_IS_RVALUE (t2))
1020         return false;
1021       /* fall through to checks for pointer types */
1022
1023     case POINTER_TYPE:
1024       if (TYPE_MODE (t1) != TYPE_MODE (t2)
1025           || TYPE_REF_CAN_ALIAS_ALL (t1) != TYPE_REF_CAN_ALIAS_ALL (t2)
1026           || !same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
1027         return false;
1028       break;
1029
1030     case METHOD_TYPE:
1031     case FUNCTION_TYPE:
1032       if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
1033         return false;
1034       if (!compparms (TYPE_ARG_TYPES (t1), TYPE_ARG_TYPES (t2)))
1035         return false;
1036       break;
1037
1038     case ARRAY_TYPE:
1039       /* Target types must match incl. qualifiers.  */
1040       if (!comp_array_types (t1, t2, !!(strict & COMPARE_REDECLARATION)))
1041         return false;
1042       break;
1043
1044     case TEMPLATE_TYPE_PARM:
1045       if (TEMPLATE_TYPE_IDX (t1) != TEMPLATE_TYPE_IDX (t2)
1046           || TEMPLATE_TYPE_LEVEL (t1) != TEMPLATE_TYPE_LEVEL (t2)
1047           || (TEMPLATE_TYPE_PARAMETER_PACK (t1)
1048               != TEMPLATE_TYPE_PARAMETER_PACK (t2)))
1049         return false;
1050       break;
1051
1052     case TYPENAME_TYPE:
1053       if (!cp_tree_equal (TYPENAME_TYPE_FULLNAME (t1),
1054                           TYPENAME_TYPE_FULLNAME (t2)))
1055         return false;
1056       if (!same_type_p (TYPE_CONTEXT (t1), TYPE_CONTEXT (t2)))
1057         return false;
1058       break;
1059
1060     case UNBOUND_CLASS_TEMPLATE:
1061       if (!cp_tree_equal (TYPE_IDENTIFIER (t1), TYPE_IDENTIFIER (t2)))
1062         return false;
1063       if (!same_type_p (TYPE_CONTEXT (t1), TYPE_CONTEXT (t2)))
1064         return false;
1065       break;
1066
1067     case COMPLEX_TYPE:
1068       if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
1069         return false;
1070       break;
1071
1072     case VECTOR_TYPE:
1073       if (TYPE_VECTOR_SUBPARTS (t1) != TYPE_VECTOR_SUBPARTS (t2)
1074           || !same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
1075         return false;
1076       break;
1077
1078     case TYPE_PACK_EXPANSION:
1079       return same_type_p (PACK_EXPANSION_PATTERN (t1),
1080                           PACK_EXPANSION_PATTERN (t2));
1081
1082     case DECLTYPE_TYPE:
1083       if (DECLTYPE_TYPE_ID_EXPR_OR_MEMBER_ACCESS_P (t1)
1084           != DECLTYPE_TYPE_ID_EXPR_OR_MEMBER_ACCESS_P (t2)
1085           || !cp_tree_equal (DECLTYPE_TYPE_EXPR (t1),
1086                              DECLTYPE_TYPE_EXPR (t2)))
1087         return false;
1088       break;
1089
1090     default:
1091       return false;
1092     }
1093
1094   /* If we get here, we know that from a target independent POV the
1095      types are the same.  Make sure the target attributes are also
1096      the same.  */
1097   return targetm.comp_type_attributes (t1, t2);
1098 }
1099
1100 /* Return true if T1 and T2 are related as allowed by STRICT.  STRICT
1101    is a bitwise-or of the COMPARE_* flags.  */
1102
1103 bool
1104 comptypes (tree t1, tree t2, int strict)
1105 {
1106   if (strict == COMPARE_STRICT)
1107     {
1108       if (t1 == t2)
1109         return true;
1110
1111       if (t1 == error_mark_node || t2 == error_mark_node)
1112         return false;
1113
1114       if (TYPE_STRUCTURAL_EQUALITY_P (t1) || TYPE_STRUCTURAL_EQUALITY_P (t2))
1115         /* At least one of the types requires structural equality, so
1116            perform a deep check. */
1117         return structural_comptypes (t1, t2, strict);
1118
1119 #ifdef ENABLE_CHECKING
1120       if (USE_CANONICAL_TYPES)
1121         {
1122           bool result = structural_comptypes (t1, t2, strict);
1123
1124           if (result && TYPE_CANONICAL (t1) != TYPE_CANONICAL (t2))
1125             /* The two types are structurally equivalent, but their
1126                canonical types were different. This is a failure of the
1127                canonical type propagation code.*/
1128             internal_error
1129               ("canonical types differ for identical types %T and %T",
1130                t1, t2);
1131           else if (!result && TYPE_CANONICAL (t1) == TYPE_CANONICAL (t2))
1132             /* Two types are structurally different, but the canonical
1133                types are the same. This means we were over-eager in
1134                assigning canonical types. */
1135             internal_error
1136               ("same canonical type node for different types %T and %T",
1137                t1, t2);
1138
1139           return result;
1140         }
1141 #else
1142       if (USE_CANONICAL_TYPES)
1143         return TYPE_CANONICAL (t1) == TYPE_CANONICAL (t2);
1144 #endif
1145       else
1146         return structural_comptypes (t1, t2, strict);
1147     }
1148   else if (strict == COMPARE_STRUCTURAL)
1149     return structural_comptypes (t1, t2, COMPARE_STRICT);
1150   else
1151     return structural_comptypes (t1, t2, strict);
1152 }
1153
1154 /* Returns 1 if TYPE1 is at least as qualified as TYPE2.  */
1155
1156 bool
1157 at_least_as_qualified_p (const_tree type1, const_tree type2)
1158 {
1159   int q1 = cp_type_quals (type1);
1160   int q2 = cp_type_quals (type2);
1161
1162   /* All qualifiers for TYPE2 must also appear in TYPE1.  */
1163   return (q1 & q2) == q2;
1164 }
1165
1166 /* Returns 1 if TYPE1 is more cv-qualified than TYPE2, -1 if TYPE2 is
1167    more cv-qualified that TYPE1, and 0 otherwise.  */
1168
1169 int
1170 comp_cv_qualification (const_tree type1, const_tree type2)
1171 {
1172   int q1 = cp_type_quals (type1);
1173   int q2 = cp_type_quals (type2);
1174
1175   if (q1 == q2)
1176     return 0;
1177
1178   if ((q1 & q2) == q2)
1179     return 1;
1180   else if ((q1 & q2) == q1)
1181     return -1;
1182
1183   return 0;
1184 }
1185
1186 /* Returns 1 if the cv-qualification signature of TYPE1 is a proper
1187    subset of the cv-qualification signature of TYPE2, and the types
1188    are similar.  Returns -1 if the other way 'round, and 0 otherwise.  */
1189
1190 int
1191 comp_cv_qual_signature (tree type1, tree type2)
1192 {
1193   if (comp_ptr_ttypes_real (type2, type1, -1))
1194     return 1;
1195   else if (comp_ptr_ttypes_real (type1, type2, -1))
1196     return -1;
1197   else
1198     return 0;
1199 }
1200 \f
1201 /* Subroutines of `comptypes'.  */
1202
1203 /* Return true if two parameter type lists PARMS1 and PARMS2 are
1204    equivalent in the sense that functions with those parameter types
1205    can have equivalent types.  The two lists must be equivalent,
1206    element by element.  */
1207
1208 bool
1209 compparms (const_tree parms1, const_tree parms2)
1210 {
1211   const_tree t1, t2;
1212
1213   /* An unspecified parmlist matches any specified parmlist
1214      whose argument types don't need default promotions.  */
1215
1216   for (t1 = parms1, t2 = parms2;
1217        t1 || t2;
1218        t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2))
1219     {
1220       /* If one parmlist is shorter than the other,
1221          they fail to match.  */
1222       if (!t1 || !t2)
1223         return false;
1224       if (!same_type_p (TREE_VALUE (t1), TREE_VALUE (t2)))
1225         return false;
1226     }
1227   return true;
1228 }
1229
1230 \f
1231 /* Process a sizeof or alignof expression where the operand is a
1232    type.  */
1233
1234 tree
1235 cxx_sizeof_or_alignof_type (tree type, enum tree_code op, bool complain)
1236 {
1237   tree value;
1238   bool dependent_p;
1239
1240   gcc_assert (op == SIZEOF_EXPR || op == ALIGNOF_EXPR);
1241   if (type == error_mark_node)
1242     return error_mark_node;
1243
1244   type = non_reference (type);
1245   if (TREE_CODE (type) == METHOD_TYPE)
1246     {
1247       if (complain && (pedantic || warn_pointer_arith))
1248         pedwarn ("invalid application of %qs to a member function",
1249                  operator_name_info[(int) op].name);
1250       value = size_one_node;
1251     }
1252
1253   dependent_p = dependent_type_p (type);
1254   if (!dependent_p)
1255     complete_type (type);
1256   if (dependent_p
1257       /* VLA types will have a non-constant size.  In the body of an
1258          uninstantiated template, we don't need to try to compute the
1259          value, because the sizeof expression is not an integral
1260          constant expression in that case.  And, if we do try to
1261          compute the value, we'll likely end up with SAVE_EXPRs, which
1262          the template substitution machinery does not expect to see.  */
1263       || (processing_template_decl
1264           && COMPLETE_TYPE_P (type)
1265           && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST))
1266     {
1267       value = build_min (op, size_type_node, type);
1268       TREE_READONLY (value) = 1;
1269       return value;
1270     }
1271
1272   return c_sizeof_or_alignof_type (complete_type (type),
1273                                    op == SIZEOF_EXPR,
1274                                    complain);
1275 }
1276
1277 /* Process a sizeof expression where the operand is an expression.  */
1278
1279 static tree
1280 cxx_sizeof_expr (tree e)
1281 {
1282   if (e == error_mark_node)
1283     return error_mark_node;
1284
1285   if (processing_template_decl)
1286     {
1287       e = build_min (SIZEOF_EXPR, size_type_node, e);
1288       TREE_SIDE_EFFECTS (e) = 0;
1289       TREE_READONLY (e) = 1;
1290
1291       return e;
1292     }
1293
1294   if (TREE_CODE (e) == COMPONENT_REF
1295       && TREE_CODE (TREE_OPERAND (e, 1)) == FIELD_DECL
1296       && DECL_C_BIT_FIELD (TREE_OPERAND (e, 1)))
1297     {
1298       error ("invalid application of %<sizeof%> to a bit-field");
1299       e = char_type_node;
1300     }
1301   else if (is_overloaded_fn (e))
1302     {
1303       pedwarn ("ISO C++ forbids applying %<sizeof%> to an expression of "
1304                "function type");
1305       e = char_type_node;
1306     }
1307   else if (type_unknown_p (e))
1308     {
1309       cxx_incomplete_type_error (e, TREE_TYPE (e));
1310       e = char_type_node;
1311     }
1312   else
1313     e = TREE_TYPE (e);
1314
1315   return cxx_sizeof_or_alignof_type (e, SIZEOF_EXPR, true);
1316 }
1317
1318 /* Implement the __alignof keyword: Return the minimum required
1319    alignment of E, measured in bytes.  For VAR_DECL's and
1320    FIELD_DECL's return DECL_ALIGN (which can be set from an
1321    "aligned" __attribute__ specification).  */
1322
1323 static tree
1324 cxx_alignof_expr (tree e)
1325 {
1326   tree t;
1327
1328   if (e == error_mark_node)
1329     return error_mark_node;
1330
1331   if (processing_template_decl)
1332     {
1333       e = build_min (ALIGNOF_EXPR, size_type_node, e);
1334       TREE_SIDE_EFFECTS (e) = 0;
1335       TREE_READONLY (e) = 1;
1336
1337       return e;
1338     }
1339
1340   if (TREE_CODE (e) == VAR_DECL)
1341     t = size_int (DECL_ALIGN_UNIT (e));
1342   else if (TREE_CODE (e) == COMPONENT_REF
1343            && TREE_CODE (TREE_OPERAND (e, 1)) == FIELD_DECL
1344            && DECL_C_BIT_FIELD (TREE_OPERAND (e, 1)))
1345     {
1346       error ("invalid application of %<__alignof%> to a bit-field");
1347       t = size_one_node;
1348     }
1349   else if (TREE_CODE (e) == COMPONENT_REF
1350            && TREE_CODE (TREE_OPERAND (e, 1)) == FIELD_DECL)
1351     t = size_int (DECL_ALIGN_UNIT (TREE_OPERAND (e, 1)));
1352   else if (is_overloaded_fn (e))
1353     {
1354       pedwarn ("ISO C++ forbids applying %<__alignof%> to an expression of "
1355                "function type");
1356       if (TREE_CODE (e) == FUNCTION_DECL)
1357         t = size_int (DECL_ALIGN_UNIT (e));
1358       else
1359         t = size_one_node;
1360     }
1361   else if (type_unknown_p (e))
1362     {
1363       cxx_incomplete_type_error (e, TREE_TYPE (e));
1364       t = size_one_node;
1365     }
1366   else
1367     return cxx_sizeof_or_alignof_type (TREE_TYPE (e), ALIGNOF_EXPR, true);
1368
1369   return fold_convert (size_type_node, t);
1370 }
1371
1372 /* Process a sizeof or alignof expression E with code OP where the operand
1373    is an expression.  */
1374
1375 tree
1376 cxx_sizeof_or_alignof_expr (tree e, enum tree_code op)
1377 {
1378   if (op == SIZEOF_EXPR)
1379     return cxx_sizeof_expr (e);
1380   else
1381     return cxx_alignof_expr (e);
1382 }
1383 \f
1384 /* EXPR is being used in a context that is not a function call.
1385    Enforce:
1386
1387      [expr.ref]
1388
1389      The expression can be used only as the left-hand operand of a
1390      member function call.
1391
1392      [expr.mptr.operator]
1393
1394      If the result of .* or ->* is a function, then that result can be
1395      used only as the operand for the function call operator ().
1396
1397    by issuing an error message if appropriate.  Returns true iff EXPR
1398    violates these rules.  */
1399
1400 bool
1401 invalid_nonstatic_memfn_p (const_tree expr)
1402 {
1403   if (TREE_CODE (TREE_TYPE (expr)) == METHOD_TYPE)
1404     {
1405       error ("invalid use of non-static member function");
1406       return true;
1407     }
1408   return false;
1409 }
1410
1411 /* If EXP is a reference to a bitfield, and the type of EXP does not
1412    match the declared type of the bitfield, return the declared type
1413    of the bitfield.  Otherwise, return NULL_TREE.  */
1414
1415 tree
1416 is_bitfield_expr_with_lowered_type (const_tree exp)
1417 {
1418   switch (TREE_CODE (exp))
1419     {
1420     case COND_EXPR:
1421       if (!is_bitfield_expr_with_lowered_type (TREE_OPERAND (exp, 1)))
1422         return NULL_TREE;
1423       return is_bitfield_expr_with_lowered_type (TREE_OPERAND (exp, 2));
1424
1425     case COMPOUND_EXPR:
1426       return is_bitfield_expr_with_lowered_type (TREE_OPERAND (exp, 1));
1427
1428     case MODIFY_EXPR:
1429     case SAVE_EXPR:
1430       return is_bitfield_expr_with_lowered_type (TREE_OPERAND (exp, 0));
1431
1432     case COMPONENT_REF:
1433       {
1434         tree field;
1435
1436         field = TREE_OPERAND (exp, 1);
1437         if (TREE_CODE (field) != FIELD_DECL || !DECL_C_BIT_FIELD (field))
1438           return NULL_TREE;
1439         if (same_type_ignoring_top_level_qualifiers_p
1440             (TREE_TYPE (exp), DECL_BIT_FIELD_TYPE (field)))
1441           return NULL_TREE;
1442         return DECL_BIT_FIELD_TYPE (field);
1443       }
1444
1445     default:
1446       return NULL_TREE;
1447     }
1448 }
1449
1450 /* Like is_bitfield_with_lowered_type, except that if EXP is not a
1451    bitfield with a lowered type, the type of EXP is returned, rather
1452    than NULL_TREE.  */
1453
1454 tree
1455 unlowered_expr_type (const_tree exp)
1456 {
1457   tree type;
1458
1459   type = is_bitfield_expr_with_lowered_type (exp);
1460   if (!type)
1461     type = TREE_TYPE (exp);
1462
1463   return type;
1464 }
1465
1466 /* Perform the conversions in [expr] that apply when an lvalue appears
1467    in an rvalue context: the lvalue-to-rvalue, array-to-pointer, and
1468    function-to-pointer conversions.  In addition, manifest constants
1469    are replaced by their values, and bitfield references are converted
1470    to their declared types.
1471
1472    Although the returned value is being used as an rvalue, this
1473    function does not wrap the returned expression in a
1474    NON_LVALUE_EXPR; the caller is expected to be mindful of the fact
1475    that the return value is no longer an lvalue.  */
1476
1477 tree
1478 decay_conversion (tree exp)
1479 {
1480   tree type;
1481   enum tree_code code;
1482
1483   type = TREE_TYPE (exp);
1484   if (type == error_mark_node)
1485     return error_mark_node;
1486
1487   if (type_unknown_p (exp))
1488     {
1489       cxx_incomplete_type_error (exp, TREE_TYPE (exp));
1490       return error_mark_node;
1491     }
1492
1493   exp = decl_constant_value (exp);
1494   if (error_operand_p (exp))
1495     return error_mark_node;
1496
1497   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
1498      Leave such NOP_EXPRs, since RHS is being used in non-lvalue context.  */
1499   code = TREE_CODE (type);
1500   if (code == VOID_TYPE)
1501     {
1502       error ("void value not ignored as it ought to be");
1503       return error_mark_node;
1504     }
1505   if (invalid_nonstatic_memfn_p (exp))
1506     return error_mark_node;
1507   if (code == FUNCTION_TYPE || is_overloaded_fn (exp))
1508     return build_unary_op (ADDR_EXPR, exp, 0);
1509   if (code == ARRAY_TYPE)
1510     {
1511       tree adr;
1512       tree ptrtype;
1513
1514       if (TREE_CODE (exp) == INDIRECT_REF)
1515         return build_nop (build_pointer_type (TREE_TYPE (type)),
1516                           TREE_OPERAND (exp, 0));
1517
1518       if (TREE_CODE (exp) == COMPOUND_EXPR)
1519         {
1520           tree op1 = decay_conversion (TREE_OPERAND (exp, 1));
1521           return build2 (COMPOUND_EXPR, TREE_TYPE (op1),
1522                          TREE_OPERAND (exp, 0), op1);
1523         }
1524
1525       if (!lvalue_p (exp)
1526           && ! (TREE_CODE (exp) == CONSTRUCTOR && TREE_STATIC (exp)))
1527         {
1528           error ("invalid use of non-lvalue array");
1529           return error_mark_node;
1530         }
1531
1532       ptrtype = build_pointer_type (TREE_TYPE (type));
1533
1534       if (TREE_CODE (exp) == VAR_DECL)
1535         {
1536           if (!cxx_mark_addressable (exp))
1537             return error_mark_node;
1538           adr = build_nop (ptrtype, build_address (exp));
1539           return adr;
1540         }
1541       /* This way is better for a COMPONENT_REF since it can
1542          simplify the offset for a component.  */
1543       adr = build_unary_op (ADDR_EXPR, exp, 1);
1544       return cp_convert (ptrtype, adr);
1545     }
1546
1547   /* If a bitfield is used in a context where integral promotion
1548      applies, then the caller is expected to have used
1549      default_conversion.  That function promotes bitfields correctly
1550      before calling this function.  At this point, if we have a
1551      bitfield referenced, we may assume that is not subject to
1552      promotion, and that, therefore, the type of the resulting rvalue
1553      is the declared type of the bitfield.  */
1554   exp = convert_bitfield_to_declared_type (exp);
1555
1556   /* We do not call rvalue() here because we do not want to wrap EXP
1557      in a NON_LVALUE_EXPR.  */
1558
1559   /* [basic.lval]
1560
1561      Non-class rvalues always have cv-unqualified types.  */
1562   type = TREE_TYPE (exp);
1563   if (!CLASS_TYPE_P (type) && cp_type_quals (type))
1564     exp = build_nop (TYPE_MAIN_VARIANT (type), exp);
1565
1566   return exp;
1567 }
1568
1569 /* Perform prepatory conversions, as part of the "usual arithmetic
1570    conversions".  In particular, as per [expr]:
1571
1572      Whenever an lvalue expression appears as an operand of an
1573      operator that expects the rvalue for that operand, the
1574      lvalue-to-rvalue, array-to-pointer, or function-to-pointer
1575      standard conversions are applied to convert the expression to an
1576      rvalue.
1577
1578    In addition, we perform integral promotions here, as those are
1579    applied to both operands to a binary operator before determining
1580    what additional conversions should apply.  */
1581
1582 tree
1583 default_conversion (tree exp)
1584 {
1585   /* Perform the integral promotions first so that bitfield
1586      expressions (which may promote to "int", even if the bitfield is
1587      declared "unsigned") are promoted correctly.  */
1588   if (INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (exp)))
1589     exp = perform_integral_promotions (exp);
1590   /* Perform the other conversions.  */
1591   exp = decay_conversion (exp);
1592
1593   return exp;
1594 }
1595
1596 /* EXPR is an expression with an integral or enumeration type.
1597    Perform the integral promotions in [conv.prom], and return the
1598    converted value.  */
1599
1600 tree
1601 perform_integral_promotions (tree expr)
1602 {
1603   tree type;
1604   tree promoted_type;
1605
1606   /* [conv.prom]
1607
1608      If the bitfield has an enumerated type, it is treated as any
1609      other value of that type for promotion purposes.  */
1610   type = is_bitfield_expr_with_lowered_type (expr);
1611   if (!type || TREE_CODE (type) != ENUMERAL_TYPE)
1612     type = TREE_TYPE (expr);
1613   gcc_assert (INTEGRAL_OR_ENUMERATION_TYPE_P (type));
1614   promoted_type = type_promotes_to (type);
1615   if (type != promoted_type)
1616     expr = cp_convert (promoted_type, expr);
1617   return expr;
1618 }
1619
1620 /* Take the address of an inline function without setting TREE_ADDRESSABLE
1621    or TREE_USED.  */
1622
1623 tree
1624 inline_conversion (tree exp)
1625 {
1626   if (TREE_CODE (exp) == FUNCTION_DECL)
1627     exp = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (exp)), exp);
1628
1629   return exp;
1630 }
1631
1632 /* Returns nonzero iff exp is a STRING_CST or the result of applying
1633    decay_conversion to one.  */
1634
1635 int
1636 string_conv_p (const_tree totype, const_tree exp, int warn)
1637 {
1638   tree t;
1639
1640   if (TREE_CODE (totype) != POINTER_TYPE)
1641     return 0;
1642
1643   t = TREE_TYPE (totype);
1644   if (!same_type_p (t, char_type_node)
1645       && !same_type_p (t, wchar_type_node))
1646     return 0;
1647
1648   if (TREE_CODE (exp) == STRING_CST)
1649     {
1650       /* Make sure that we don't try to convert between char and wchar_t.  */
1651       if (!same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (exp))), t))
1652         return 0;
1653     }
1654   else
1655     {
1656       /* Is this a string constant which has decayed to 'const char *'?  */
1657       t = build_pointer_type (build_qualified_type (t, TYPE_QUAL_CONST));
1658       if (!same_type_p (TREE_TYPE (exp), t))
1659         return 0;
1660       STRIP_NOPS (exp);
1661       if (TREE_CODE (exp) != ADDR_EXPR
1662           || TREE_CODE (TREE_OPERAND (exp, 0)) != STRING_CST)
1663         return 0;
1664     }
1665
1666   /* This warning is not very useful, as it complains about printf.  */
1667   if (warn)
1668     warning (OPT_Wwrite_strings,
1669              "deprecated conversion from string constant to %qT",
1670              totype);
1671
1672   return 1;
1673 }
1674
1675 /* Given a COND_EXPR, MIN_EXPR, or MAX_EXPR in T, return it in a form that we
1676    can, for example, use as an lvalue.  This code used to be in
1677    unary_complex_lvalue, but we needed it to deal with `a = (d == c) ? b : c'
1678    expressions, where we're dealing with aggregates.  But now it's again only
1679    called from unary_complex_lvalue.  The case (in particular) that led to
1680    this was with CODE == ADDR_EXPR, since it's not an lvalue when we'd
1681    get it there.  */
1682
1683 static tree
1684 rationalize_conditional_expr (enum tree_code code, tree t)
1685 {
1686   /* For MIN_EXPR or MAX_EXPR, fold-const.c has arranged things so that
1687      the first operand is always the one to be used if both operands
1688      are equal, so we know what conditional expression this used to be.  */
1689   if (TREE_CODE (t) == MIN_EXPR || TREE_CODE (t) == MAX_EXPR)
1690     {
1691       tree op0 = TREE_OPERAND (t, 0);
1692       tree op1 = TREE_OPERAND (t, 1);
1693
1694       /* The following code is incorrect if either operand side-effects.  */
1695       gcc_assert (!TREE_SIDE_EFFECTS (op0)
1696                   && !TREE_SIDE_EFFECTS (op1));
1697       return
1698         build_conditional_expr (build_x_binary_op ((TREE_CODE (t) == MIN_EXPR
1699                                                     ? LE_EXPR : GE_EXPR),
1700                                                    op0, TREE_CODE (op0),
1701                                                    op1, TREE_CODE (op1),
1702                                                    /*overloaded_p=*/NULL),
1703                             build_unary_op (code, op0, 0),
1704                             build_unary_op (code, op1, 0));
1705     }
1706
1707   return
1708     build_conditional_expr (TREE_OPERAND (t, 0),
1709                             build_unary_op (code, TREE_OPERAND (t, 1), 0),
1710                             build_unary_op (code, TREE_OPERAND (t, 2), 0));
1711 }
1712
1713 /* Given the TYPE of an anonymous union field inside T, return the
1714    FIELD_DECL for the field.  If not found return NULL_TREE.  Because
1715    anonymous unions can nest, we must also search all anonymous unions
1716    that are directly reachable.  */
1717
1718 tree
1719 lookup_anon_field (tree t, tree type)
1720 {
1721   tree field;
1722
1723   for (field = TYPE_FIELDS (t); field; field = TREE_CHAIN (field))
1724     {
1725       if (TREE_STATIC (field))
1726         continue;
1727       if (TREE_CODE (field) != FIELD_DECL || DECL_ARTIFICIAL (field))
1728         continue;
1729
1730       /* If we find it directly, return the field.  */
1731       if (DECL_NAME (field) == NULL_TREE
1732           && type == TYPE_MAIN_VARIANT (TREE_TYPE (field)))
1733         {
1734           return field;
1735         }
1736
1737       /* Otherwise, it could be nested, search harder.  */
1738       if (DECL_NAME (field) == NULL_TREE
1739           && ANON_AGGR_TYPE_P (TREE_TYPE (field)))
1740         {
1741           tree subfield = lookup_anon_field (TREE_TYPE (field), type);
1742           if (subfield)
1743             return subfield;
1744         }
1745     }
1746   return NULL_TREE;
1747 }
1748
1749 /* Build an expression representing OBJECT.MEMBER.  OBJECT is an
1750    expression; MEMBER is a DECL or baselink.  If ACCESS_PATH is
1751    non-NULL, it indicates the path to the base used to name MEMBER.
1752    If PRESERVE_REFERENCE is true, the expression returned will have
1753    REFERENCE_TYPE if the MEMBER does.  Otherwise, the expression
1754    returned will have the type referred to by the reference.
1755
1756    This function does not perform access control; that is either done
1757    earlier by the parser when the name of MEMBER is resolved to MEMBER
1758    itself, or later when overload resolution selects one of the
1759    functions indicated by MEMBER.  */
1760
1761 tree
1762 build_class_member_access_expr (tree object, tree member,
1763                                 tree access_path, bool preserve_reference)
1764 {
1765   tree object_type;
1766   tree member_scope;
1767   tree result = NULL_TREE;
1768
1769   if (error_operand_p (object) || error_operand_p (member))
1770     return error_mark_node;
1771
1772   gcc_assert (DECL_P (member) || BASELINK_P (member));
1773
1774   /* [expr.ref]
1775
1776      The type of the first expression shall be "class object" (of a
1777      complete type).  */
1778   object_type = TREE_TYPE (object);
1779   if (!currently_open_class (object_type)
1780       && !complete_type_or_else (object_type, object))
1781     return error_mark_node;
1782   if (!CLASS_TYPE_P (object_type))
1783     {
1784       error ("request for member %qD in %qE, which is of non-class type %qT",
1785              member, object, object_type);
1786       return error_mark_node;
1787     }
1788
1789   /* The standard does not seem to actually say that MEMBER must be a
1790      member of OBJECT_TYPE.  However, that is clearly what is
1791      intended.  */
1792   if (DECL_P (member))
1793     {
1794       member_scope = DECL_CLASS_CONTEXT (member);
1795       mark_used (member);
1796       if (TREE_DEPRECATED (member))
1797         warn_deprecated_use (member);
1798     }
1799   else
1800     member_scope = BINFO_TYPE (BASELINK_BINFO (member));
1801   /* If MEMBER is from an anonymous aggregate, MEMBER_SCOPE will
1802      presently be the anonymous union.  Go outwards until we find a
1803      type related to OBJECT_TYPE.  */
1804   while (ANON_AGGR_TYPE_P (member_scope)
1805          && !same_type_ignoring_top_level_qualifiers_p (member_scope,
1806                                                         object_type))
1807     member_scope = TYPE_CONTEXT (member_scope);
1808   if (!member_scope || !DERIVED_FROM_P (member_scope, object_type))
1809     {
1810       if (TREE_CODE (member) == FIELD_DECL)
1811         error ("invalid use of nonstatic data member %qE", member);
1812       else
1813         error ("%qD is not a member of %qT", member, object_type);
1814       return error_mark_node;
1815     }
1816
1817   /* Transform `(a, b).x' into `(*(a, &b)).x', `(a ? b : c).x' into
1818      `(*(a ?  &b : &c)).x', and so on.  A COND_EXPR is only an lvalue
1819      in the front end; only _DECLs and _REFs are lvalues in the back end.  */
1820   {
1821     tree temp = unary_complex_lvalue (ADDR_EXPR, object);
1822     if (temp)
1823       object = build_indirect_ref (temp, NULL);
1824   }
1825
1826   /* In [expr.ref], there is an explicit list of the valid choices for
1827      MEMBER.  We check for each of those cases here.  */
1828   if (TREE_CODE (member) == VAR_DECL)
1829     {
1830       /* A static data member.  */
1831       result = member;
1832       /* If OBJECT has side-effects, they are supposed to occur.  */
1833       if (TREE_SIDE_EFFECTS (object))
1834         result = build2 (COMPOUND_EXPR, TREE_TYPE (result), object, result);
1835     }
1836   else if (TREE_CODE (member) == FIELD_DECL)
1837     {
1838       /* A non-static data member.  */
1839       bool null_object_p;
1840       int type_quals;
1841       tree member_type;
1842
1843       null_object_p = (TREE_CODE (object) == INDIRECT_REF
1844                        && integer_zerop (TREE_OPERAND (object, 0)));
1845
1846       /* Convert OBJECT to the type of MEMBER.  */
1847       if (!same_type_p (TYPE_MAIN_VARIANT (object_type),
1848                         TYPE_MAIN_VARIANT (member_scope)))
1849         {
1850           tree binfo;
1851           base_kind kind;
1852
1853           binfo = lookup_base (access_path ? access_path : object_type,
1854                                member_scope, ba_unique,  &kind);
1855           if (binfo == error_mark_node)
1856             return error_mark_node;
1857
1858           /* It is invalid to try to get to a virtual base of a
1859              NULL object.  The most common cause is invalid use of
1860              offsetof macro.  */
1861           if (null_object_p && kind == bk_via_virtual)
1862             {
1863               error ("invalid access to non-static data member %qD of "
1864                      "NULL object",
1865                      member);
1866               error ("(perhaps the %<offsetof%> macro was used incorrectly)");
1867               return error_mark_node;
1868             }
1869
1870           /* Convert to the base.  */
1871           object = build_base_path (PLUS_EXPR, object, binfo,
1872                                     /*nonnull=*/1);
1873           /* If we found the base successfully then we should be able
1874              to convert to it successfully.  */
1875           gcc_assert (object != error_mark_node);
1876         }
1877
1878       /* Complain about other invalid uses of offsetof, even though they will
1879          give the right answer.  Note that we complain whether or not they
1880          actually used the offsetof macro, since there's no way to know at this
1881          point.  So we just give a warning, instead of a pedwarn.  */
1882       /* Do not produce this warning for base class field references, because
1883          we know for a fact that didn't come from offsetof.  This does occur
1884          in various testsuite cases where a null object is passed where a
1885          vtable access is required.  */
1886       if (null_object_p && warn_invalid_offsetof
1887           && CLASSTYPE_NON_POD_P (object_type)
1888           && !DECL_FIELD_IS_BASE (member)
1889           && !skip_evaluation)
1890         {
1891           warning (0, "invalid access to non-static data member %qD of NULL object",
1892                    member);
1893           warning (0, "(perhaps the %<offsetof%> macro was used incorrectly)");
1894         }
1895
1896       /* If MEMBER is from an anonymous aggregate, we have converted
1897          OBJECT so that it refers to the class containing the
1898          anonymous union.  Generate a reference to the anonymous union
1899          itself, and recur to find MEMBER.  */
1900       if (ANON_AGGR_TYPE_P (DECL_CONTEXT (member))
1901           /* When this code is called from build_field_call, the
1902              object already has the type of the anonymous union.
1903              That is because the COMPONENT_REF was already
1904              constructed, and was then disassembled before calling
1905              build_field_call.  After the function-call code is
1906              cleaned up, this waste can be eliminated.  */
1907           && (!same_type_ignoring_top_level_qualifiers_p
1908               (TREE_TYPE (object), DECL_CONTEXT (member))))
1909         {
1910           tree anonymous_union;
1911
1912           anonymous_union = lookup_anon_field (TREE_TYPE (object),
1913                                                DECL_CONTEXT (member));
1914           object = build_class_member_access_expr (object,
1915                                                    anonymous_union,
1916                                                    /*access_path=*/NULL_TREE,
1917                                                    preserve_reference);
1918         }
1919
1920       /* Compute the type of the field, as described in [expr.ref].  */
1921       type_quals = TYPE_UNQUALIFIED;
1922       member_type = TREE_TYPE (member);
1923       if (TREE_CODE (member_type) != REFERENCE_TYPE)
1924         {
1925           type_quals = (cp_type_quals (member_type)
1926                         | cp_type_quals (object_type));
1927
1928           /* A field is const (volatile) if the enclosing object, or the
1929              field itself, is const (volatile).  But, a mutable field is
1930              not const, even within a const object.  */
1931           if (DECL_MUTABLE_P (member))
1932             type_quals &= ~TYPE_QUAL_CONST;
1933           member_type = cp_build_qualified_type (member_type, type_quals);
1934         }
1935
1936       result = build3 (COMPONENT_REF, member_type, object, member,
1937                        NULL_TREE);
1938       result = fold_if_not_in_template (result);
1939
1940       /* Mark the expression const or volatile, as appropriate.  Even
1941          though we've dealt with the type above, we still have to mark the
1942          expression itself.  */
1943       if (type_quals & TYPE_QUAL_CONST)
1944         TREE_READONLY (result) = 1;
1945       if (type_quals & TYPE_QUAL_VOLATILE)
1946         TREE_THIS_VOLATILE (result) = 1;
1947     }
1948   else if (BASELINK_P (member))
1949     {
1950       /* The member is a (possibly overloaded) member function.  */
1951       tree functions;
1952       tree type;
1953
1954       /* If the MEMBER is exactly one static member function, then we
1955          know the type of the expression.  Otherwise, we must wait
1956          until overload resolution has been performed.  */
1957       functions = BASELINK_FUNCTIONS (member);
1958       if (TREE_CODE (functions) == FUNCTION_DECL
1959           && DECL_STATIC_FUNCTION_P (functions))
1960         type = TREE_TYPE (functions);
1961       else
1962         type = unknown_type_node;
1963       /* Note that we do not convert OBJECT to the BASELINK_BINFO
1964          base.  That will happen when the function is called.  */
1965       result = build3 (COMPONENT_REF, type, object, member, NULL_TREE);
1966     }
1967   else if (TREE_CODE (member) == CONST_DECL)
1968     {
1969       /* The member is an enumerator.  */
1970       result = member;
1971       /* If OBJECT has side-effects, they are supposed to occur.  */
1972       if (TREE_SIDE_EFFECTS (object))
1973         result = build2 (COMPOUND_EXPR, TREE_TYPE (result),
1974                          object, result);
1975     }
1976   else
1977     {
1978       error ("invalid use of %qD", member);
1979       return error_mark_node;
1980     }
1981
1982   if (!preserve_reference)
1983     /* [expr.ref]
1984
1985        If E2 is declared to have type "reference to T", then ... the
1986        type of E1.E2 is T.  */
1987     result = convert_from_reference (result);
1988
1989   return result;
1990 }
1991
1992 /* Return the destructor denoted by OBJECT.SCOPE::~DTOR_NAME, or, if
1993    SCOPE is NULL, by OBJECT.~DTOR_NAME.  */
1994
1995 static tree
1996 lookup_destructor (tree object, tree scope, tree dtor_name)
1997 {
1998   tree object_type = TREE_TYPE (object);
1999   tree dtor_type = TREE_OPERAND (dtor_name, 0);
2000   tree expr;
2001
2002   if (scope && !check_dtor_name (scope, dtor_type))
2003     {
2004       error ("qualified type %qT does not match destructor name ~%qT",
2005              scope, dtor_type);
2006       return error_mark_node;
2007     }
2008   if (!DERIVED_FROM_P (dtor_type, TYPE_MAIN_VARIANT (object_type)))
2009     {
2010       error ("the type being destroyed is %qT, but the destructor refers to %qT",
2011              TYPE_MAIN_VARIANT (object_type), dtor_type);
2012       return error_mark_node;
2013     }
2014   expr = lookup_member (dtor_type, complete_dtor_identifier,
2015                         /*protect=*/1, /*want_type=*/false);
2016   expr = (adjust_result_of_qualified_name_lookup
2017           (expr, dtor_type, object_type));
2018   return expr;
2019 }
2020
2021 /* An expression of the form "A::template B" has been resolved to
2022    DECL.  Issue a diagnostic if B is not a template or template
2023    specialization.  */
2024
2025 void
2026 check_template_keyword (tree decl)
2027 {
2028   /* The standard says:
2029
2030       [temp.names]
2031
2032       If a name prefixed by the keyword template is not a member
2033       template, the program is ill-formed.
2034
2035      DR 228 removed the restriction that the template be a member
2036      template.
2037
2038      DR 96, if accepted would add the further restriction that explicit
2039      template arguments must be provided if the template keyword is
2040      used, but, as of 2005-10-16, that DR is still in "drafting".  If
2041      this DR is accepted, then the semantic checks here can be
2042      simplified, as the entity named must in fact be a template
2043      specialization, rather than, as at present, a set of overloaded
2044      functions containing at least one template function.  */
2045   if (TREE_CODE (decl) != TEMPLATE_DECL
2046       && TREE_CODE (decl) != TEMPLATE_ID_EXPR)
2047     {
2048       if (!is_overloaded_fn (decl))
2049         pedwarn ("%qD is not a template", decl);
2050       else
2051         {
2052           tree fns;
2053           fns = decl;
2054           if (BASELINK_P (fns))
2055             fns = BASELINK_FUNCTIONS (fns);
2056           while (fns)
2057             {
2058               tree fn = OVL_CURRENT (fns);
2059               if (TREE_CODE (fn) == TEMPLATE_DECL
2060                   || TREE_CODE (fn) == TEMPLATE_ID_EXPR)
2061                 break;
2062               if (TREE_CODE (fn) == FUNCTION_DECL
2063                   && DECL_USE_TEMPLATE (fn)
2064                   && PRIMARY_TEMPLATE_P (DECL_TI_TEMPLATE (fn)))
2065                 break;
2066               fns = OVL_NEXT (fns);
2067             }
2068           if (!fns)
2069             pedwarn ("%qD is not a template", decl);
2070         }
2071     }
2072 }
2073
2074 /* This function is called by the parser to process a class member
2075    access expression of the form OBJECT.NAME.  NAME is a node used by
2076    the parser to represent a name; it is not yet a DECL.  It may,
2077    however, be a BASELINK where the BASELINK_FUNCTIONS is a
2078    TEMPLATE_ID_EXPR.  Templates must be looked up by the parser, and
2079    there is no reason to do the lookup twice, so the parser keeps the
2080    BASELINK.  TEMPLATE_P is true iff NAME was explicitly declared to
2081    be a template via the use of the "A::template B" syntax.  */
2082
2083 tree
2084 finish_class_member_access_expr (tree object, tree name, bool template_p)
2085 {
2086   tree expr;
2087   tree object_type;
2088   tree member;
2089   tree access_path = NULL_TREE;
2090   tree orig_object = object;
2091   tree orig_name = name;
2092
2093   if (object == error_mark_node || name == error_mark_node)
2094     return error_mark_node;
2095
2096   /* If OBJECT is an ObjC class instance, we must obey ObjC access rules.  */
2097   if (!objc_is_public (object, name))
2098     return error_mark_node;
2099
2100   object_type = TREE_TYPE (object);
2101
2102   if (processing_template_decl)
2103     {
2104       if (/* If OBJECT_TYPE is dependent, so is OBJECT.NAME.  */
2105           dependent_type_p (object_type)
2106           /* If NAME is just an IDENTIFIER_NODE, then the expression
2107              is dependent.  */
2108           || TREE_CODE (object) == IDENTIFIER_NODE
2109           /* If NAME is "f<args>", where either 'f' or 'args' is
2110              dependent, then the expression is dependent.  */
2111           || (TREE_CODE (name) == TEMPLATE_ID_EXPR
2112               && dependent_template_id_p (TREE_OPERAND (name, 0),
2113                                           TREE_OPERAND (name, 1)))
2114           /* If NAME is "T::X" where "T" is dependent, then the
2115              expression is dependent.  */
2116           || (TREE_CODE (name) == SCOPE_REF
2117               && TYPE_P (TREE_OPERAND (name, 0))
2118               && dependent_type_p (TREE_OPERAND (name, 0))))
2119         return build_min_nt (COMPONENT_REF, object, name, NULL_TREE);
2120       object = build_non_dependent_expr (object);
2121     }
2122
2123   /* [expr.ref]
2124
2125      The type of the first expression shall be "class object" (of a
2126      complete type).  */
2127   if (!currently_open_class (object_type)
2128       && !complete_type_or_else (object_type, object))
2129     return error_mark_node;
2130   if (!CLASS_TYPE_P (object_type))
2131     {
2132       error ("request for member %qD in %qE, which is of non-class type %qT",
2133              name, object, object_type);
2134       return error_mark_node;
2135     }
2136
2137   if (BASELINK_P (name))
2138     /* A member function that has already been looked up.  */
2139     member = name;
2140   else
2141     {
2142       bool is_template_id = false;
2143       tree template_args = NULL_TREE;
2144       tree scope;
2145
2146       if (TREE_CODE (name) == TEMPLATE_ID_EXPR)
2147         {
2148           is_template_id = true;
2149           template_args = TREE_OPERAND (name, 1);
2150           name = TREE_OPERAND (name, 0);
2151
2152           if (TREE_CODE (name) == OVERLOAD)
2153             name = DECL_NAME (get_first_fn (name));
2154           else if (DECL_P (name))
2155             name = DECL_NAME (name);
2156         }
2157
2158       if (TREE_CODE (name) == SCOPE_REF)
2159         {
2160           /* A qualified name.  The qualifying class or namespace `S'
2161              has already been looked up; it is either a TYPE or a
2162              NAMESPACE_DECL.  */
2163           scope = TREE_OPERAND (name, 0);
2164           name = TREE_OPERAND (name, 1);
2165
2166           /* If SCOPE is a namespace, then the qualified name does not
2167              name a member of OBJECT_TYPE.  */
2168           if (TREE_CODE (scope) == NAMESPACE_DECL)
2169             {
2170               error ("%<%D::%D%> is not a member of %qT",
2171                      scope, name, object_type);
2172               return error_mark_node;
2173             }
2174
2175           gcc_assert (CLASS_TYPE_P (scope));
2176           gcc_assert (TREE_CODE (name) == IDENTIFIER_NODE
2177                       || TREE_CODE (name) == BIT_NOT_EXPR);
2178
2179           /* Find the base of OBJECT_TYPE corresponding to SCOPE.  */
2180           access_path = lookup_base (object_type, scope, ba_check, NULL);
2181           if (access_path == error_mark_node)
2182             return error_mark_node;
2183           if (!access_path)
2184             {
2185               error ("%qT is not a base of %qT", scope, object_type);
2186               return error_mark_node;
2187             }
2188         }
2189       else
2190         {
2191           scope = NULL_TREE;
2192           access_path = object_type;
2193         }
2194
2195       if (TREE_CODE (name) == BIT_NOT_EXPR)
2196         member = lookup_destructor (object, scope, name);
2197       else
2198         {
2199           /* Look up the member.  */
2200           member = lookup_member (access_path, name, /*protect=*/1,
2201                                   /*want_type=*/false);
2202           if (member == NULL_TREE)
2203             {
2204               error ("%qD has no member named %qE", object_type, name);
2205               return error_mark_node;
2206             }
2207           if (member == error_mark_node)
2208             return error_mark_node;
2209         }
2210
2211       if (is_template_id)
2212         {
2213           tree template = member;
2214
2215           if (BASELINK_P (template))
2216             template = lookup_template_function (template, template_args);
2217           else
2218             {
2219               error ("%qD is not a member template function", name);
2220               return error_mark_node;
2221             }
2222         }
2223     }
2224
2225   if (TREE_DEPRECATED (member))
2226     warn_deprecated_use (member);
2227
2228   if (template_p)
2229     check_template_keyword (member);
2230
2231   expr = build_class_member_access_expr (object, member, access_path,
2232                                          /*preserve_reference=*/false);
2233   if (processing_template_decl && expr != error_mark_node)
2234     {
2235       if (BASELINK_P (member))
2236         {
2237           if (TREE_CODE (orig_name) == SCOPE_REF)
2238             BASELINK_QUALIFIED_P (member) = 1;
2239           orig_name = member;
2240         }
2241       return build_min_non_dep (COMPONENT_REF, expr,
2242                                 orig_object, orig_name,
2243                                 NULL_TREE);
2244     }
2245
2246   return expr;
2247 }
2248
2249 /* Return an expression for the MEMBER_NAME field in the internal
2250    representation of PTRMEM, a pointer-to-member function.  (Each
2251    pointer-to-member function type gets its own RECORD_TYPE so it is
2252    more convenient to access the fields by name than by FIELD_DECL.)
2253    This routine converts the NAME to a FIELD_DECL and then creates the
2254    node for the complete expression.  */
2255
2256 tree
2257 build_ptrmemfunc_access_expr (tree ptrmem, tree member_name)
2258 {
2259   tree ptrmem_type;
2260   tree member;
2261   tree member_type;
2262
2263   /* This code is a stripped down version of
2264      build_class_member_access_expr.  It does not work to use that
2265      routine directly because it expects the object to be of class
2266      type.  */
2267   ptrmem_type = TREE_TYPE (ptrmem);
2268   gcc_assert (TYPE_PTRMEMFUNC_P (ptrmem_type));
2269   member = lookup_member (ptrmem_type, member_name, /*protect=*/0,
2270                           /*want_type=*/false);
2271   member_type = cp_build_qualified_type (TREE_TYPE (member),
2272                                          cp_type_quals (ptrmem_type));
2273   return fold_build3 (COMPONENT_REF, member_type,
2274                       ptrmem, member, NULL_TREE);
2275 }
2276
2277 /* Given an expression PTR for a pointer, return an expression
2278    for the value pointed to.
2279    ERRORSTRING is the name of the operator to appear in error messages.
2280
2281    This function may need to overload OPERATOR_FNNAME.
2282    Must also handle REFERENCE_TYPEs for C++.  */
2283
2284 tree
2285 build_x_indirect_ref (tree expr, const char *errorstring)
2286 {
2287   tree orig_expr = expr;
2288   tree rval;
2289
2290   if (processing_template_decl)
2291     {
2292       if (type_dependent_expression_p (expr))
2293         return build_min_nt (INDIRECT_REF, expr);
2294       expr = build_non_dependent_expr (expr);
2295     }
2296
2297   rval = build_new_op (INDIRECT_REF, LOOKUP_NORMAL, expr, NULL_TREE,
2298                        NULL_TREE, /*overloaded_p=*/NULL);
2299   if (!rval)
2300     rval = build_indirect_ref (expr, errorstring);
2301
2302   if (processing_template_decl && rval != error_mark_node)
2303     return build_min_non_dep (INDIRECT_REF, rval, orig_expr);
2304   else
2305     return rval;
2306 }
2307
2308 tree
2309 build_indirect_ref (tree ptr, const char *errorstring)
2310 {
2311   tree pointer, type;
2312
2313   if (ptr == error_mark_node)
2314     return error_mark_node;
2315
2316   if (ptr == current_class_ptr)
2317     return current_class_ref;
2318
2319   pointer = (TREE_CODE (TREE_TYPE (ptr)) == REFERENCE_TYPE
2320              ? ptr : decay_conversion (ptr));
2321   type = TREE_TYPE (pointer);
2322
2323   if (POINTER_TYPE_P (type))
2324     {
2325       /* [expr.unary.op]
2326
2327          If the type of the expression is "pointer to T," the type
2328          of  the  result  is  "T."
2329
2330          We must use the canonical variant because certain parts of
2331          the back end, like fold, do pointer comparisons between
2332          types.  */
2333       tree t = canonical_type_variant (TREE_TYPE (type));
2334
2335       if (TREE_CODE (ptr) == CONVERT_EXPR
2336           || TREE_CODE (ptr) == NOP_EXPR
2337           || TREE_CODE (ptr) == VIEW_CONVERT_EXPR)
2338         {
2339           /* If a warning is issued, mark it to avoid duplicates from
2340              the backend.  This only needs to be done at
2341              warn_strict_aliasing > 2.  */
2342           if (warn_strict_aliasing > 2)
2343             if (strict_aliasing_warning (TREE_TYPE (TREE_OPERAND (ptr, 0)),
2344                                          type, TREE_OPERAND (ptr, 0)))
2345               TREE_NO_WARNING (ptr) = 1;
2346         }
2347
2348       if (VOID_TYPE_P (t))
2349         {
2350           /* A pointer to incomplete type (other than cv void) can be
2351              dereferenced [expr.unary.op]/1  */
2352           error ("%qT is not a pointer-to-object type", type);
2353           return error_mark_node;
2354         }
2355       else if (TREE_CODE (pointer) == ADDR_EXPR
2356                && same_type_p (t, TREE_TYPE (TREE_OPERAND (pointer, 0))))
2357         /* The POINTER was something like `&x'.  We simplify `*&x' to
2358            `x'.  */
2359         return TREE_OPERAND (pointer, 0);
2360       else
2361         {
2362           tree ref = build1 (INDIRECT_REF, t, pointer);
2363
2364           /* We *must* set TREE_READONLY when dereferencing a pointer to const,
2365              so that we get the proper error message if the result is used
2366              to assign to.  Also, &* is supposed to be a no-op.  */
2367           TREE_READONLY (ref) = CP_TYPE_CONST_P (t);
2368           TREE_THIS_VOLATILE (ref) = CP_TYPE_VOLATILE_P (t);
2369           TREE_SIDE_EFFECTS (ref)
2370             = (TREE_THIS_VOLATILE (ref) || TREE_SIDE_EFFECTS (pointer));
2371           return ref;
2372         }
2373     }
2374   /* `pointer' won't be an error_mark_node if we were given a
2375      pointer to member, so it's cool to check for this here.  */
2376   else if (TYPE_PTR_TO_MEMBER_P (type))
2377     error ("invalid use of %qs on pointer to member", errorstring);
2378   else if (pointer != error_mark_node)
2379     {
2380       if (errorstring)
2381         error ("invalid type argument of %qs", errorstring);
2382       else
2383         error ("invalid type argument");
2384     }
2385   return error_mark_node;
2386 }
2387
2388 /* This handles expressions of the form "a[i]", which denotes
2389    an array reference.
2390
2391    This is logically equivalent in C to *(a+i), but we may do it differently.
2392    If A is a variable or a member, we generate a primitive ARRAY_REF.
2393    This avoids forcing the array out of registers, and can work on
2394    arrays that are not lvalues (for example, members of structures returned
2395    by functions).
2396
2397    If INDEX is of some user-defined type, it must be converted to
2398    integer type.  Otherwise, to make a compatible PLUS_EXPR, it
2399    will inherit the type of the array, which will be some pointer type.  */
2400
2401 tree
2402 build_array_ref (tree array, tree idx)
2403 {
2404   if (idx == 0)
2405     {
2406       error ("subscript missing in array reference");
2407       return error_mark_node;
2408     }
2409
2410   if (TREE_TYPE (array) == error_mark_node
2411       || TREE_TYPE (idx) == error_mark_node)
2412     return error_mark_node;
2413
2414   /* If ARRAY is a COMPOUND_EXPR or COND_EXPR, move our reference
2415      inside it.  */
2416   switch (TREE_CODE (array))
2417     {
2418     case COMPOUND_EXPR:
2419       {
2420         tree value = build_array_ref (TREE_OPERAND (array, 1), idx);
2421         return build2 (COMPOUND_EXPR, TREE_TYPE (value),
2422                        TREE_OPERAND (array, 0), value);
2423       }
2424
2425     case COND_EXPR:
2426       return build_conditional_expr
2427         (TREE_OPERAND (array, 0),
2428          build_array_ref (TREE_OPERAND (array, 1), idx),
2429          build_array_ref (TREE_OPERAND (array, 2), idx));
2430
2431     default:
2432       break;
2433     }
2434
2435   if (TREE_CODE (TREE_TYPE (array)) == ARRAY_TYPE)
2436     {
2437       tree rval, type;
2438
2439       warn_array_subscript_with_type_char (idx);
2440
2441       if (!INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (idx)))
2442         {
2443           error ("array subscript is not an integer");
2444           return error_mark_node;
2445         }
2446
2447       /* Apply integral promotions *after* noticing character types.
2448          (It is unclear why we do these promotions -- the standard
2449          does not say that we should.  In fact, the natural thing would
2450          seem to be to convert IDX to ptrdiff_t; we're performing
2451          pointer arithmetic.)  */
2452       idx = perform_integral_promotions (idx);
2453
2454       /* An array that is indexed by a non-constant
2455          cannot be stored in a register; we must be able to do
2456          address arithmetic on its address.
2457          Likewise an array of elements of variable size.  */
2458       if (TREE_CODE (idx) != INTEGER_CST
2459           || (COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (array)))
2460               && (TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (array))))
2461                   != INTEGER_CST)))
2462         {
2463           if (!cxx_mark_addressable (array))
2464             return error_mark_node;
2465         }
2466
2467       /* An array that is indexed by a constant value which is not within
2468          the array bounds cannot be stored in a register either; because we
2469          would get a crash in store_bit_field/extract_bit_field when trying
2470          to access a non-existent part of the register.  */
2471       if (TREE_CODE (idx) == INTEGER_CST
2472           && TYPE_DOMAIN (TREE_TYPE (array))
2473           && ! int_fits_type_p (idx, TYPE_DOMAIN (TREE_TYPE (array))))
2474         {
2475           if (!cxx_mark_addressable (array))
2476             return error_mark_node;
2477         }
2478
2479       if (pedantic && !lvalue_p (array))
2480         pedwarn ("ISO C++ forbids subscripting non-lvalue array");
2481
2482       /* Note in C++ it is valid to subscript a `register' array, since
2483          it is valid to take the address of something with that
2484          storage specification.  */
2485       if (extra_warnings)
2486         {
2487           tree foo = array;
2488           while (TREE_CODE (foo) == COMPONENT_REF)
2489             foo = TREE_OPERAND (foo, 0);
2490           if (TREE_CODE (foo) == VAR_DECL && DECL_REGISTER (foo))
2491             warning (OPT_Wextra, "subscripting array declared %<register%>");
2492         }
2493
2494       type = TREE_TYPE (TREE_TYPE (array));
2495       rval = build4 (ARRAY_REF, type, array, idx, NULL_TREE, NULL_TREE);
2496       /* Array ref is const/volatile if the array elements are
2497          or if the array is..  */
2498       TREE_READONLY (rval)
2499         |= (CP_TYPE_CONST_P (type) | TREE_READONLY (array));
2500       TREE_SIDE_EFFECTS (rval)
2501         |= (CP_TYPE_VOLATILE_P (type) | TREE_SIDE_EFFECTS (array));
2502       TREE_THIS_VOLATILE (rval)
2503         |= (CP_TYPE_VOLATILE_P (type) | TREE_THIS_VOLATILE (array));
2504       return require_complete_type (fold_if_not_in_template (rval));
2505     }
2506
2507   {
2508     tree ar = default_conversion (array);
2509     tree ind = default_conversion (idx);
2510
2511     /* Put the integer in IND to simplify error checking.  */
2512     if (TREE_CODE (TREE_TYPE (ar)) == INTEGER_TYPE)
2513       {
2514         tree temp = ar;
2515         ar = ind;
2516         ind = temp;
2517       }
2518
2519     if (ar == error_mark_node)
2520       return ar;
2521
2522     if (TREE_CODE (TREE_TYPE (ar)) != POINTER_TYPE)
2523       {
2524         error ("subscripted value is neither array nor pointer");
2525         return error_mark_node;
2526       }
2527     if (TREE_CODE (TREE_TYPE (ind)) != INTEGER_TYPE)
2528       {
2529         error ("array subscript is not an integer");
2530         return error_mark_node;
2531       }
2532
2533     warn_array_subscript_with_type_char (idx);
2534
2535     return build_indirect_ref (cp_build_binary_op (PLUS_EXPR, ar, ind),
2536                                "array indexing");
2537   }
2538 }
2539 \f
2540 /* Resolve a pointer to member function.  INSTANCE is the object
2541    instance to use, if the member points to a virtual member.
2542
2543    This used to avoid checking for virtual functions if basetype
2544    has no virtual functions, according to an earlier ANSI draft.
2545    With the final ISO C++ rules, such an optimization is
2546    incorrect: A pointer to a derived member can be static_cast
2547    to pointer-to-base-member, as long as the dynamic object
2548    later has the right member.  */
2549
2550 tree
2551 get_member_function_from_ptrfunc (tree *instance_ptrptr, tree function)
2552 {
2553   if (TREE_CODE (function) == OFFSET_REF)
2554     function = TREE_OPERAND (function, 1);
2555
2556   if (TYPE_PTRMEMFUNC_P (TREE_TYPE (function)))
2557     {
2558       tree idx, delta, e1, e2, e3, vtbl, basetype;
2559       tree fntype = TYPE_PTRMEMFUNC_FN_TYPE (TREE_TYPE (function));
2560
2561       tree instance_ptr = *instance_ptrptr;
2562       tree instance_save_expr = 0;
2563       if (instance_ptr == error_mark_node)
2564         {
2565           if (TREE_CODE (function) == PTRMEM_CST)
2566             {
2567               /* Extracting the function address from a pmf is only
2568                  allowed with -Wno-pmf-conversions. It only works for
2569                  pmf constants.  */
2570               e1 = build_addr_func (PTRMEM_CST_MEMBER (function));
2571               e1 = convert (fntype, e1);
2572               return e1;
2573             }
2574           else
2575             {
2576               error ("object missing in use of %qE", function);
2577               return error_mark_node;
2578             }
2579         }
2580
2581       if (TREE_SIDE_EFFECTS (instance_ptr))
2582         instance_ptr = instance_save_expr = save_expr (instance_ptr);
2583
2584       if (TREE_SIDE_EFFECTS (function))
2585         function = save_expr (function);
2586
2587       /* Start by extracting all the information from the PMF itself.  */
2588       e3 = pfn_from_ptrmemfunc (function);
2589       delta = build_ptrmemfunc_access_expr (function, delta_identifier);
2590       idx = build1 (NOP_EXPR, vtable_index_type, e3);
2591       switch (TARGET_PTRMEMFUNC_VBIT_LOCATION)
2592         {
2593         case ptrmemfunc_vbit_in_pfn:
2594           e1 = cp_build_binary_op (BIT_AND_EXPR, idx, integer_one_node);
2595           idx = cp_build_binary_op (MINUS_EXPR, idx, integer_one_node);
2596           break;
2597
2598         case ptrmemfunc_vbit_in_delta:
2599           e1 = cp_build_binary_op (BIT_AND_EXPR, delta, integer_one_node);
2600           delta = cp_build_binary_op (RSHIFT_EXPR, delta, integer_one_node);
2601           break;
2602
2603         default:
2604           gcc_unreachable ();
2605         }
2606
2607       /* Convert down to the right base before using the instance.  A
2608          special case is that in a pointer to member of class C, C may
2609          be incomplete.  In that case, the function will of course be
2610          a member of C, and no conversion is required.  In fact,
2611          lookup_base will fail in that case, because incomplete
2612          classes do not have BINFOs.  */
2613       basetype = TYPE_METHOD_BASETYPE (TREE_TYPE (fntype));
2614       if (!same_type_ignoring_top_level_qualifiers_p
2615           (basetype, TREE_TYPE (TREE_TYPE (instance_ptr))))
2616         {
2617           basetype = lookup_base (TREE_TYPE (TREE_TYPE (instance_ptr)),
2618                                   basetype, ba_check, NULL);
2619           instance_ptr = build_base_path (PLUS_EXPR, instance_ptr, basetype,
2620                                           1);
2621           if (instance_ptr == error_mark_node)
2622             return error_mark_node;
2623         }
2624       /* ...and then the delta in the PMF.  */
2625       instance_ptr = build2 (POINTER_PLUS_EXPR, TREE_TYPE (instance_ptr),
2626                              instance_ptr, fold_convert (sizetype, delta));
2627
2628       /* Hand back the adjusted 'this' argument to our caller.  */
2629       *instance_ptrptr = instance_ptr;
2630
2631       /* Next extract the vtable pointer from the object.  */
2632       vtbl = build1 (NOP_EXPR, build_pointer_type (vtbl_ptr_type_node),
2633                      instance_ptr);
2634       vtbl = build_indirect_ref (vtbl, NULL);
2635
2636       /* Finally, extract the function pointer from the vtable.  */
2637       e2 = fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (vtbl), vtbl,
2638                         fold_convert (sizetype, idx));
2639       e2 = build_indirect_ref (e2, NULL);
2640       TREE_CONSTANT (e2) = 1;
2641       TREE_INVARIANT (e2) = 1;
2642
2643       /* When using function descriptors, the address of the
2644          vtable entry is treated as a function pointer.  */
2645       if (TARGET_VTABLE_USES_DESCRIPTORS)
2646         e2 = build1 (NOP_EXPR, TREE_TYPE (e2),
2647                      build_unary_op (ADDR_EXPR, e2, /*noconvert=*/1));
2648
2649       e2 = fold_convert (TREE_TYPE (e3), e2);
2650       e1 = build_conditional_expr (e1, e2, e3);
2651
2652       /* Make sure this doesn't get evaluated first inside one of the
2653          branches of the COND_EXPR.  */
2654       if (instance_save_expr)
2655         e1 = build2 (COMPOUND_EXPR, TREE_TYPE (e1),
2656                      instance_save_expr, e1);
2657
2658       function = e1;
2659     }
2660   return function;
2661 }
2662
2663 tree
2664 build_function_call (tree function, tree params)
2665 {
2666   tree fntype, fndecl;
2667   tree name = NULL_TREE;
2668   int is_method;
2669   tree original = function;
2670   int nargs, parm_types_len;
2671   tree *argarray;
2672   tree parm_types;
2673
2674   /* For Objective-C, convert any calls via a cast to OBJC_TYPE_REF
2675      expressions, like those used for ObjC messenger dispatches.  */
2676   function = objc_rewrite_function_call (function, params);
2677
2678   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
2679      Strip such NOP_EXPRs, since FUNCTION is used in non-lvalue context.  */
2680   if (TREE_CODE (function) == NOP_EXPR
2681       && TREE_TYPE (function) == TREE_TYPE (TREE_OPERAND (function, 0)))
2682     function = TREE_OPERAND (function, 0);
2683
2684   if (TREE_CODE (function) == FUNCTION_DECL)
2685     {
2686       name = DECL_NAME (function);
2687
2688       mark_used (function);
2689       fndecl = function;
2690
2691       /* Convert anything with function type to a pointer-to-function.  */
2692       if (pedantic && DECL_MAIN_P (function))
2693         pedwarn ("ISO C++ forbids calling %<::main%> from within program");
2694
2695       /* Differs from default_conversion by not setting TREE_ADDRESSABLE
2696          (because calling an inline function does not mean the function
2697          needs to be separately compiled).  */
2698
2699       if (DECL_INLINE (function))
2700         function = inline_conversion (function);
2701       else
2702         function = build_addr_func (function);
2703     }
2704   else
2705     {
2706       fndecl = NULL_TREE;
2707
2708       function = build_addr_func (function);
2709     }
2710
2711   if (function == error_mark_node)
2712     return error_mark_node;
2713
2714   fntype = TREE_TYPE (function);
2715
2716   if (TYPE_PTRMEMFUNC_P (fntype))
2717     {
2718       error ("must use %<.*%> or %<->*%> to call pointer-to-member "
2719              "function in %<%E (...)%>",
2720              original);
2721       return error_mark_node;
2722     }
2723
2724   is_method = (TREE_CODE (fntype) == POINTER_TYPE
2725                && TREE_CODE (TREE_TYPE (fntype)) == METHOD_TYPE);
2726
2727   if (!((TREE_CODE (fntype) == POINTER_TYPE
2728          && TREE_CODE (TREE_TYPE (fntype)) == FUNCTION_TYPE)
2729         || is_method
2730         || TREE_CODE (function) == TEMPLATE_ID_EXPR))
2731     {
2732       error ("%qE cannot be used as a function", original);
2733       return error_mark_node;
2734     }
2735
2736   /* fntype now gets the type of function pointed to.  */
2737   fntype = TREE_TYPE (fntype);
2738   parm_types = TYPE_ARG_TYPES (fntype);
2739
2740   /* Allocate storage for converted arguments.  */
2741   parm_types_len = list_length (parm_types);
2742   nargs = list_length (params);
2743   if (parm_types_len > nargs)
2744     nargs = parm_types_len;
2745   argarray = (tree *) alloca (nargs * sizeof (tree));
2746
2747   /* Convert the parameters to the types declared in the
2748      function prototype, or apply default promotions.  */
2749   nargs = convert_arguments (nargs, argarray, parm_types,
2750                              params, fndecl, LOOKUP_NORMAL);
2751   if (nargs < 0)
2752     return error_mark_node;
2753
2754   /* Check for errors in format strings and inappropriately
2755      null parameters.  */
2756
2757   check_function_arguments (TYPE_ATTRIBUTES (fntype), nargs, argarray,
2758                             parm_types);
2759
2760   return build_cxx_call (function, nargs, argarray);
2761 }
2762 \f
2763 /* Convert the actual parameter expressions in the list VALUES
2764    to the types in the list TYPELIST.
2765    If parmdecls is exhausted, or when an element has NULL as its type,
2766    perform the default conversions.
2767
2768    Store the converted arguments in ARGARRAY.  NARGS is the size of this array.
2769
2770    NAME is an IDENTIFIER_NODE or 0.  It is used only for error messages.
2771
2772    This is also where warnings about wrong number of args are generated.
2773
2774    Returns the actual number of arguments processed (which might be less
2775    than NARGS), or -1 on error.
2776
2777    VALUES is a chain of TREE_LIST nodes with the elements of the list
2778    in the TREE_VALUE slots of those nodes.
2779
2780    In C++, unspecified trailing parameters can be filled in with their
2781    default arguments, if such were specified.  Do so here.  */
2782
2783 static int
2784 convert_arguments (int nargs, tree *argarray,
2785                    tree typelist, tree values, tree fndecl, int flags)
2786 {
2787   tree typetail, valtail;
2788   const char *called_thing = 0;
2789   int i = 0;
2790
2791   /* Argument passing is always copy-initialization.  */
2792   flags |= LOOKUP_ONLYCONVERTING;
2793
2794   if (fndecl)
2795     {
2796       if (TREE_CODE (TREE_TYPE (fndecl)) == METHOD_TYPE)
2797         {
2798           if (DECL_NAME (fndecl) == NULL_TREE
2799               || IDENTIFIER_HAS_TYPE_VALUE (DECL_NAME (fndecl)))
2800             called_thing = "constructor";
2801           else
2802             called_thing = "member function";
2803         }
2804       else
2805         called_thing = "function";
2806     }
2807
2808   for (valtail = values, typetail = typelist;
2809        valtail;
2810        valtail = TREE_CHAIN (valtail), i++)
2811     {
2812       tree type = typetail ? TREE_VALUE (typetail) : 0;
2813       tree val = TREE_VALUE (valtail);
2814
2815       if (val == error_mark_node || type == error_mark_node)
2816         return -1;
2817
2818       if (type == void_type_node)
2819         {
2820           if (fndecl)
2821             {
2822               error ("too many arguments to %s %q+#D", called_thing, fndecl);
2823               error ("at this point in file");
2824             }
2825           else
2826             error ("too many arguments to function");
2827           return i;
2828         }
2829
2830       /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
2831          Strip such NOP_EXPRs, since VAL is used in non-lvalue context.  */
2832       if (TREE_CODE (val) == NOP_EXPR
2833           && TREE_TYPE (val) == TREE_TYPE (TREE_OPERAND (val, 0))
2834           && (type == 0 || TREE_CODE (type) != REFERENCE_TYPE))
2835         val = TREE_OPERAND (val, 0);
2836
2837       if (type == 0 || TREE_CODE (type) != REFERENCE_TYPE)
2838         {
2839           if (TREE_CODE (TREE_TYPE (val)) == ARRAY_TYPE
2840               || TREE_CODE (TREE_TYPE (val)) == FUNCTION_TYPE
2841               || TREE_CODE (TREE_TYPE (val)) == METHOD_TYPE)
2842             val = decay_conversion (val);
2843         }
2844
2845       if (val == error_mark_node)
2846         return -1;
2847
2848       if (type != 0)
2849         {
2850           /* Formal parm type is specified by a function prototype.  */
2851           tree parmval;
2852
2853           if (!COMPLETE_TYPE_P (complete_type (type)))
2854             {
2855               if (fndecl)
2856                 error ("parameter %P of %qD has incomplete type %qT",
2857                        i, fndecl, type);
2858               else
2859                 error ("parameter %P has incomplete type %qT", i, type);
2860               parmval = error_mark_node;
2861             }
2862           else
2863             {
2864               parmval = convert_for_initialization
2865                 (NULL_TREE, type, val, flags,
2866                  "argument passing", fndecl, i);
2867               parmval = convert_for_arg_passing (type, parmval);
2868             }
2869
2870           if (parmval == error_mark_node)
2871             return -1;
2872
2873           argarray[i] = parmval;
2874         }
2875       else
2876         {
2877           if (fndecl && DECL_BUILT_IN (fndecl)
2878               && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_CONSTANT_P)
2879             /* Don't do ellipsis conversion for __built_in_constant_p
2880                as this will result in spurious warnings for non-POD
2881                types.  */
2882             val = require_complete_type (val);
2883           else
2884             val = convert_arg_to_ellipsis (val);
2885
2886           argarray[i] = val;
2887         }
2888
2889       if (typetail)
2890         typetail = TREE_CHAIN (typetail);
2891     }
2892
2893   if (typetail != 0 && typetail != void_list_node)
2894     {
2895       /* See if there are default arguments that can be used.  Because
2896          we hold default arguments in the FUNCTION_TYPE (which is so
2897          wrong), we can see default parameters here from deduced
2898          contexts (and via typeof) for indirect function calls.
2899          Fortunately we know whether we have a function decl to
2900          provide default arguments in a language conformant
2901          manner.  */
2902       if (fndecl && TREE_PURPOSE (typetail)
2903           && TREE_CODE (TREE_PURPOSE (typetail)) != DEFAULT_ARG)
2904         {
2905           for (; typetail != void_list_node; ++i)
2906             {
2907               tree parmval
2908                 = convert_default_arg (TREE_VALUE (typetail),
2909                                        TREE_PURPOSE (typetail),
2910                                        fndecl, i);
2911
2912               if (parmval == error_mark_node)
2913                 return -1;
2914
2915               argarray[i] = parmval;
2916               typetail = TREE_CHAIN (typetail);
2917               /* ends with `...'.  */
2918               if (typetail == NULL_TREE)
2919                 break;
2920             }
2921         }
2922       else
2923         {
2924           if (fndecl)
2925             {
2926               error ("too few arguments to %s %q+#D", called_thing, fndecl);
2927               error ("at this point in file");
2928             }
2929           else
2930             error ("too few arguments to function");
2931           return -1;
2932         }
2933     }
2934
2935   gcc_assert (i <= nargs);
2936   return i;
2937 }
2938 \f
2939 /* Build a binary-operation expression, after performing default
2940    conversions on the operands.  CODE is the kind of expression to
2941    build.  ARG1 and ARG2 are the arguments.  ARG1_CODE and ARG2_CODE
2942    are the tree codes which correspond to ARG1 and ARG2 when issuing
2943    warnings about possibly misplaced parentheses.  They may differ
2944    from the TREE_CODE of ARG1 and ARG2 if the parser has done constant
2945    folding (e.g., if the parser sees "a | 1 + 1", it may call this
2946    routine with ARG2 being an INTEGER_CST and ARG2_CODE == PLUS_EXPR).
2947    To avoid issuing any parentheses warnings, pass ARG1_CODE and/or
2948    ARG2_CODE as ERROR_MARK.  */
2949
2950 tree
2951 build_x_binary_op (enum tree_code code, tree arg1, enum tree_code arg1_code,
2952                    tree arg2, enum tree_code arg2_code, bool *overloaded_p)
2953 {
2954   tree orig_arg1;
2955   tree orig_arg2;
2956   tree expr;
2957
2958   orig_arg1 = arg1;
2959   orig_arg2 = arg2;
2960
2961   if (processing_template_decl)
2962     {
2963       if (type_dependent_expression_p (arg1)
2964           || type_dependent_expression_p (arg2))
2965         return build_min_nt (code, arg1, arg2);
2966       arg1 = build_non_dependent_expr (arg1);
2967       arg2 = build_non_dependent_expr (arg2);
2968     }
2969
2970   if (code == DOTSTAR_EXPR)
2971     expr = build_m_component_ref (arg1, arg2);
2972   else
2973     expr = build_new_op (code, LOOKUP_NORMAL, arg1, arg2, NULL_TREE,
2974                          overloaded_p);
2975
2976   /* Check for cases such as x+y<<z which users are likely to
2977      misinterpret.  But don't warn about obj << x + y, since that is a
2978      common idiom for I/O.  */
2979   if (warn_parentheses
2980       && !processing_template_decl
2981       && !error_operand_p (arg1)
2982       && !error_operand_p (arg2)
2983       && (code != LSHIFT_EXPR
2984           || !CLASS_TYPE_P (TREE_TYPE (arg1))))
2985     warn_about_parentheses (code, arg1_code, arg2_code);
2986
2987   if (processing_template_decl && expr != error_mark_node)
2988     return build_min_non_dep (code, expr, orig_arg1, orig_arg2);
2989
2990   return expr;
2991 }
2992
2993 /* Build a binary-operation expression without default conversions.
2994    CODE is the kind of expression to build.
2995    This function differs from `build' in several ways:
2996    the data type of the result is computed and recorded in it,
2997    warnings are generated if arg data types are invalid,
2998    special handling for addition and subtraction of pointers is known,
2999    and some optimization is done (operations on narrow ints
3000    are done in the narrower type when that gives the same result).
3001    Constant folding is also done before the result is returned.
3002
3003    Note that the operands will never have enumeral types
3004    because either they have just had the default conversions performed
3005    or they have both just been converted to some other type in which
3006    the arithmetic is to be done.
3007
3008    C++: must do special pointer arithmetic when implementing
3009    multiple inheritance, and deal with pointer to member functions.  */
3010
3011 tree
3012 build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
3013                  int convert_p ATTRIBUTE_UNUSED)
3014 {
3015   tree op0, op1;
3016   enum tree_code code0, code1;
3017   tree type0, type1;
3018   const char *invalid_op_diag;
3019
3020   /* Expression code to give to the expression when it is built.
3021      Normally this is CODE, which is what the caller asked for,
3022      but in some special cases we change it.  */
3023   enum tree_code resultcode = code;
3024
3025   /* Data type in which the computation is to be performed.
3026      In the simplest cases this is the common type of the arguments.  */
3027   tree result_type = NULL;
3028
3029   /* Nonzero means operands have already been type-converted
3030      in whatever way is necessary.
3031      Zero means they need to be converted to RESULT_TYPE.  */
3032   int converted = 0;
3033
3034   /* Nonzero means create the expression with this type, rather than
3035      RESULT_TYPE.  */
3036   tree build_type = 0;
3037
3038   /* Nonzero means after finally constructing the expression
3039      convert it to this type.  */
3040   tree final_type = 0;
3041
3042   tree result;
3043
3044   /* Nonzero if this is an operation like MIN or MAX which can
3045      safely be computed in short if both args are promoted shorts.
3046      Also implies COMMON.
3047      -1 indicates a bitwise operation; this makes a difference
3048      in the exact conditions for when it is safe to do the operation
3049      in a narrower mode.  */
3050   int shorten = 0;
3051
3052   /* Nonzero if this is a comparison operation;
3053      if both args are promoted shorts, compare the original shorts.
3054      Also implies COMMON.  */
3055   int short_compare = 0;
3056
3057   /* Nonzero if this is a right-shift operation, which can be computed on the
3058      original short and then promoted if the operand is a promoted short.  */
3059   int short_shift = 0;
3060
3061   /* Nonzero means set RESULT_TYPE to the common type of the args.  */
3062   int common = 0;
3063
3064   /* True if both operands have arithmetic type.  */
3065   bool arithmetic_types_p;
3066
3067   /* Apply default conversions.  */
3068   op0 = orig_op0;
3069   op1 = orig_op1;
3070
3071   if (code == TRUTH_AND_EXPR || code == TRUTH_ANDIF_EXPR
3072       || code == TRUTH_OR_EXPR || code == TRUTH_ORIF_EXPR
3073       || code == TRUTH_XOR_EXPR)
3074     {
3075       if (!really_overloaded_fn (op0))
3076         op0 = decay_conversion (op0);
3077       if (!really_overloaded_fn (op1))
3078         op1 = decay_conversion (op1);
3079     }
3080   else
3081     {
3082       if (!really_overloaded_fn (op0))
3083         op0 = default_conversion (op0);
3084       if (!really_overloaded_fn (op1))
3085         op1 = default_conversion (op1);
3086     }
3087
3088   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
3089   STRIP_TYPE_NOPS (op0);
3090   STRIP_TYPE_NOPS (op1);
3091
3092   /* DTRT if one side is an overloaded function, but complain about it.  */
3093   if (type_unknown_p (op0))
3094     {
3095       tree t = instantiate_type (TREE_TYPE (op1), op0, tf_none);
3096       if (t != error_mark_node)
3097         {
3098           pedwarn ("assuming cast to type %qT from overloaded function",
3099                    TREE_TYPE (t));
3100           op0 = t;
3101         }
3102     }
3103   if (type_unknown_p (op1))
3104     {
3105       tree t = instantiate_type (TREE_TYPE (op0), op1, tf_none);
3106       if (t != error_mark_node)
3107         {
3108           pedwarn ("assuming cast to type %qT from overloaded function",
3109                    TREE_TYPE (t));
3110           op1 = t;
3111         }
3112     }
3113
3114   type0 = TREE_TYPE (op0);
3115   type1 = TREE_TYPE (op1);
3116
3117   /* The expression codes of the data types of the arguments tell us
3118      whether the arguments are integers, floating, pointers, etc.  */
3119   code0 = TREE_CODE (type0);
3120   code1 = TREE_CODE (type1);
3121
3122   /* If an error was already reported for one of the arguments,
3123      avoid reporting another error.  */
3124
3125   if (code0 == ERROR_MARK || code1 == ERROR_MARK)
3126     return error_mark_node;
3127
3128   if ((invalid_op_diag
3129        = targetm.invalid_binary_op (code, type0, type1)))
3130     {
3131       error (invalid_op_diag);
3132       return error_mark_node;
3133     }
3134
3135   switch (code)
3136     {
3137     case MINUS_EXPR:
3138       /* Subtraction of two similar pointers.
3139          We must subtract them as integers, then divide by object size.  */
3140       if (code0 == POINTER_TYPE && code1 == POINTER_TYPE
3141           && same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (type0),
3142                                                         TREE_TYPE (type1)))
3143         return pointer_diff (op0, op1, common_type (type0, type1));
3144       /* In all other cases except pointer - int, the usual arithmetic
3145          rules aply.  */
3146       else if (!(code0 == POINTER_TYPE && code1 == INTEGER_TYPE))
3147         {
3148           common = 1;
3149           break;
3150         }
3151       /* The pointer - int case is just like pointer + int; fall
3152          through.  */
3153     case PLUS_EXPR:
3154       if ((code0 == POINTER_TYPE || code1 == POINTER_TYPE)
3155           && (code0 == INTEGER_TYPE || code1 == INTEGER_TYPE))
3156         {
3157           tree ptr_operand;
3158           tree int_operand;
3159           ptr_operand = ((code0 == POINTER_TYPE) ? op0 : op1);
3160           int_operand = ((code0 == INTEGER_TYPE) ? op0 : op1);
3161           if (processing_template_decl)
3162             {
3163               result_type = TREE_TYPE (ptr_operand);
3164               break;
3165             }
3166           return cp_pointer_int_sum (code,
3167                                      ptr_operand,
3168                                      int_operand);
3169         }
3170       common = 1;
3171       break;
3172
3173     case MULT_EXPR:
3174       common = 1;
3175       break;
3176
3177     case TRUNC_DIV_EXPR:
3178     case CEIL_DIV_EXPR:
3179     case FLOOR_DIV_EXPR:
3180     case ROUND_DIV_EXPR:
3181     case EXACT_DIV_EXPR:
3182       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
3183            || code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
3184           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
3185               || code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE))
3186         {
3187           enum tree_code tcode0 = code0, tcode1 = code1;
3188
3189           warn_for_div_by_zero (op1);
3190
3191           if (tcode0 == COMPLEX_TYPE || tcode0 == VECTOR_TYPE)
3192             tcode0 = TREE_CODE (TREE_TYPE (TREE_TYPE (op0)));
3193           if (tcode1 == COMPLEX_TYPE || tcode1 == VECTOR_TYPE)
3194             tcode1 = TREE_CODE (TREE_TYPE (TREE_TYPE (op1)));
3195
3196           if (!(tcode0 == INTEGER_TYPE && tcode1 == INTEGER_TYPE))
3197             resultcode = RDIV_EXPR;
3198           else
3199             /* When dividing two signed integers, we have to promote to int.
3200                unless we divide by a constant != -1.  Note that default
3201                conversion will have been performed on the operands at this
3202                point, so we have to dig out the original type to find out if
3203                it was unsigned.  */
3204             shorten = ((TREE_CODE (op0) == NOP_EXPR
3205                         && TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op0, 0))))
3206                        || (TREE_CODE (op1) == INTEGER_CST
3207                            && ! integer_all_onesp (op1)));
3208
3209           common = 1;
3210         }
3211       break;
3212
3213     case BIT_AND_EXPR:
3214     case BIT_IOR_EXPR:
3215     case BIT_XOR_EXPR:
3216       if ((code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
3217           || (code0 == VECTOR_TYPE && code1 == VECTOR_TYPE
3218               && !VECTOR_FLOAT_TYPE_P (type0)
3219               && !VECTOR_FLOAT_TYPE_P (type1)))
3220         shorten = -1;
3221       break;
3222
3223     case TRUNC_MOD_EXPR:
3224     case FLOOR_MOD_EXPR:
3225       warn_for_div_by_zero (op1);
3226
3227       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
3228         {
3229           /* Although it would be tempting to shorten always here, that loses
3230              on some targets, since the modulo instruction is undefined if the
3231              quotient can't be represented in the computation mode.  We shorten
3232              only if unsigned or if dividing by something we know != -1.  */
3233           shorten = ((TREE_CODE (op0) == NOP_EXPR
3234                       && TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op0, 0))))
3235                      || (TREE_CODE (op1) == INTEGER_CST
3236                          && ! integer_all_onesp (op1)));
3237           common = 1;
3238         }
3239       break;
3240
3241     case TRUTH_ANDIF_EXPR:
3242     case TRUTH_ORIF_EXPR:
3243     case TRUTH_AND_EXPR:
3244     case TRUTH_OR_EXPR:
3245       result_type = boolean_type_node;
3246       break;
3247
3248       /* Shift operations: result has same type as first operand;
3249          always convert second operand to int.
3250          Also set SHORT_SHIFT if shifting rightward.  */
3251
3252     case RSHIFT_EXPR:
3253       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
3254         {
3255           result_type = type0;
3256           if (TREE_CODE (op1) == INTEGER_CST)
3257             {
3258               if (tree_int_cst_lt (op1, integer_zero_node))
3259                 warning (0, "right shift count is negative");
3260               else
3261                 {
3262                   if (! integer_zerop (op1))
3263                     short_shift = 1;
3264                   if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
3265                     warning (0, "right shift count >= width of type");
3266                 }
3267             }
3268           /* Convert the shift-count to an integer, regardless of
3269              size of value being shifted.  */
3270           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
3271             op1 = cp_convert (integer_type_node, op1);
3272           /* Avoid converting op1 to result_type later.  */
3273           converted = 1;
3274         }
3275       break;
3276
3277     case LSHIFT_EXPR:
3278       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
3279         {
3280           result_type = type0;
3281           if (TREE_CODE (op1) == INTEGER_CST)
3282             {
3283               if (tree_int_cst_lt (op1, integer_zero_node))
3284                 warning (0, "left shift count is negative");
3285               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
3286                 warning (0, "left shift count >= width of type");
3287             }
3288           /* Convert the shift-count to an integer, regardless of
3289              size of value being shifted.  */
3290           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
3291             op1 = cp_convert (integer_type_node, op1);
3292           /* Avoid converting op1 to result_type later.  */
3293           converted = 1;
3294         }
3295       break;
3296
3297     case RROTATE_EXPR:
3298     case LROTATE_EXPR:
3299       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
3300         {
3301           result_type = type0;
3302           if (TREE_CODE (op1) == INTEGER_CST)
3303             {
3304               if (tree_int_cst_lt (op1, integer_zero_node))
3305                 warning (0, (code == LROTATE_EXPR)
3306                             ? G_("left rotate count is negative")
3307                             : G_("right rotate count is negative"));
3308               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
3309                 warning (0, (code == LROTATE_EXPR)
3310                             ? G_("left rotate count >= width of type")
3311                             : G_("right rotate count >= width of type"));
3312             }
3313           /* Convert the shift-count to an integer, regardless of
3314              size of value being shifted.  */
3315           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
3316             op1 = cp_convert (integer_type_node, op1);
3317         }
3318       break;
3319
3320     case EQ_EXPR:
3321     case NE_EXPR:
3322       if (code0 == REAL_TYPE || code1 == REAL_TYPE)
3323         warning (OPT_Wfloat_equal,
3324                  "comparing floating point with == or != is unsafe");
3325       if ((TREE_CODE (orig_op0) == STRING_CST && !integer_zerop (op1))
3326           || (TREE_CODE (orig_op1) == STRING_CST && !integer_zerop (op0)))
3327         warning (OPT_Waddress, "comparison with string literal results in unspecified behaviour");
3328
3329       build_type = boolean_type_node;
3330       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
3331            || code0 == COMPLEX_TYPE)
3332           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
3333               || code1 == COMPLEX_TYPE))
3334         short_compare = 1;
3335       else if ((code0 == POINTER_TYPE && code1 == POINTER_TYPE)
3336                || (TYPE_PTRMEM_P (type0) && TYPE_PTRMEM_P (type1)))
3337         result_type = composite_pointer_type (type0, type1, op0, op1,
3338                                               "comparison");
3339       else if ((code0 == POINTER_TYPE || TYPE_PTRMEM_P (type0))
3340                && null_ptr_cst_p (op1))
3341         {
3342           if (TREE_CODE (op0) == ADDR_EXPR
3343               && decl_with_nonnull_addr_p (TREE_OPERAND (op0, 0)))
3344             warning (OPT_Waddress, "the address of %qD will never be NULL",
3345                      TREE_OPERAND (op0, 0));
3346           result_type = type0;
3347         }
3348       else if ((code1 == POINTER_TYPE || TYPE_PTRMEM_P (type1))
3349                && null_ptr_cst_p (op0))
3350         {
3351           if (TREE_CODE (op1) == ADDR_EXPR
3352               && decl_with_nonnull_addr_p (TREE_OPERAND (op1, 0)))
3353             warning (OPT_Waddress, "the address of %qD will never be NULL",
3354                      TREE_OPERAND (op1, 0));
3355           result_type = type1;
3356         }
3357       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
3358         {
3359           result_type = type0;
3360           error ("ISO C++ forbids comparison between pointer and integer");
3361         }
3362       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
3363         {
3364           result_type = type1;
3365           error ("ISO C++ forbids comparison between pointer and integer");
3366         }
3367       else if (TYPE_PTRMEMFUNC_P (type0) && null_ptr_cst_p (op1))
3368         {
3369           if (TARGET_PTRMEMFUNC_VBIT_LOCATION
3370               == ptrmemfunc_vbit_in_delta)
3371             {
3372               tree pfn0 = pfn_from_ptrmemfunc (op0);
3373               tree delta0 = build_ptrmemfunc_access_expr (op0,
3374                                                           delta_identifier);
3375               tree e1 = cp_build_binary_op (EQ_EXPR,
3376                                             pfn0,
3377                                             fold_convert (TREE_TYPE (pfn0),
3378                                                           integer_zero_node));
3379               tree e2 = cp_build_binary_op (BIT_AND_EXPR,
3380                                             delta0,
3381                                             integer_one_node);
3382               e2 = cp_build_binary_op (EQ_EXPR, e2, integer_zero_node);
3383               op0 = cp_build_binary_op (TRUTH_ANDIF_EXPR, e1, e2);
3384               op1 = cp_convert (TREE_TYPE (op0), integer_one_node);
3385             }
3386           else
3387             {
3388               op0 = build_ptrmemfunc_access_expr (op0, pfn_identifier);
3389               op1 = cp_convert (TREE_TYPE (op0), integer_zero_node);
3390             }
3391           result_type = TREE_TYPE (op0);
3392         }
3393       else if (TYPE_PTRMEMFUNC_P (type1) && null_ptr_cst_p (op0))
3394         return cp_build_binary_op (code, op1, op0);
3395       else if (TYPE_PTRMEMFUNC_P (type0) && TYPE_PTRMEMFUNC_P (type1)
3396                && same_type_p (type0, type1))
3397         {
3398           /* E will be the final comparison.  */
3399           tree e;
3400           /* E1 and E2 are for scratch.  */
3401           tree e1;
3402           tree e2;
3403           tree pfn0;
3404           tree pfn1;
3405           tree delta0;
3406           tree delta1;
3407
3408           if (TREE_SIDE_EFFECTS (op0))
3409             op0 = save_expr (op0);
3410           if (TREE_SIDE_EFFECTS (op1))
3411             op1 = save_expr (op1);
3412
3413           pfn0 = pfn_from_ptrmemfunc (op0);
3414           pfn1 = pfn_from_ptrmemfunc (op1);
3415           delta0 = build_ptrmemfunc_access_expr (op0,
3416                                                  delta_identifier);
3417           delta1 = build_ptrmemfunc_access_expr (op1,
3418                                                  delta_identifier);
3419           if (TARGET_PTRMEMFUNC_VBIT_LOCATION
3420               == ptrmemfunc_vbit_in_delta)
3421             {
3422               /* We generate:
3423
3424                  (op0.pfn == op1.pfn
3425                   && ((op0.delta == op1.delta)
3426                        || (!op0.pfn && op0.delta & 1 == 0
3427                            && op1.delta & 1 == 0))
3428
3429                  The reason for the `!op0.pfn' bit is that a NULL
3430                  pointer-to-member is any member with a zero PFN and
3431                  LSB of the DELTA field is 0.  */
3432
3433               e1 = cp_build_binary_op (BIT_AND_EXPR,
3434                                        delta0,
3435                                        integer_one_node);
3436               e1 = cp_build_binary_op (EQ_EXPR, e1, integer_zero_node);
3437               e2 = cp_build_binary_op (BIT_AND_EXPR,
3438                                        delta1,
3439                                        integer_one_node);
3440               e2 = cp_build_binary_op (EQ_EXPR, e2, integer_zero_node);
3441               e1 = cp_build_binary_op (TRUTH_ANDIF_EXPR, e2, e1);
3442               e2 = cp_build_binary_op (EQ_EXPR,
3443                                        pfn0,
3444                                        fold_convert (TREE_TYPE (pfn0),
3445                                                      integer_zero_node));
3446               e2 = cp_build_binary_op (TRUTH_ANDIF_EXPR, e2, e1);
3447               e1 = cp_build_binary_op (EQ_EXPR, delta0, delta1);
3448               e1 = cp_build_binary_op (TRUTH_ORIF_EXPR, e1, e2);
3449             }
3450           else
3451             {
3452               /* We generate:
3453
3454                  (op0.pfn == op1.pfn
3455                  && (!op0.pfn || op0.delta == op1.delta))
3456
3457                  The reason for the `!op0.pfn' bit is that a NULL
3458                  pointer-to-member is any member with a zero PFN; the
3459                  DELTA field is unspecified.  */
3460
3461               e1 = cp_build_binary_op (EQ_EXPR, delta0, delta1);
3462               e2 = cp_build_binary_op (EQ_EXPR,
3463                                        pfn0,
3464                                        fold_convert (TREE_TYPE (pfn0),
3465                                                    integer_zero_node));
3466               e1 = cp_build_binary_op (TRUTH_ORIF_EXPR, e1, e2);
3467             }
3468           e2 = build2 (EQ_EXPR, boolean_type_node, pfn0, pfn1);
3469           e = cp_build_binary_op (TRUTH_ANDIF_EXPR, e2, e1);
3470           if (code == EQ_EXPR)
3471             return e;
3472           return cp_build_binary_op (EQ_EXPR, e, integer_zero_node);
3473         }
3474       else
3475         {
3476           gcc_assert (!TYPE_PTRMEMFUNC_P (type0)
3477                       || !same_type_p (TYPE_PTRMEMFUNC_FN_TYPE (type0),
3478                                        type1));
3479           gcc_assert (!TYPE_PTRMEMFUNC_P (type1)
3480                       || !same_type_p (TYPE_PTRMEMFUNC_FN_TYPE (type1),
3481                                        type0));
3482         }
3483
3484       break;
3485
3486     case MAX_EXPR:
3487     case MIN_EXPR:
3488       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
3489            && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
3490         shorten = 1;
3491       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
3492         result_type = composite_pointer_type (type0, type1, op0, op1,
3493                                               "comparison");
3494       break;
3495
3496     case LE_EXPR:
3497     case GE_EXPR:
3498     case LT_EXPR:
3499     case GT_EXPR:
3500       if (TREE_CODE (orig_op0) == STRING_CST
3501           || TREE_CODE (orig_op1) == STRING_CST)
3502         warning (OPT_Waddress, "comparison with string literal results in unspecified behaviour");
3503
3504       build_type = boolean_type_node;
3505       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
3506            && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
3507         short_compare = 1;
3508       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
3509         result_type = composite_pointer_type (type0, type1, op0, op1,
3510                                               "comparison");
3511       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
3512                && integer_zerop (op1))
3513         result_type = type0;
3514       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
3515                && integer_zerop (op0))
3516         result_type = type1;
3517       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
3518         {
3519           result_type = type0;
3520           pedwarn ("ISO C++ forbids comparison between pointer and integer");
3521         }
3522       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
3523         {
3524           result_type = type1;
3525           pedwarn ("ISO C++ forbids comparison between pointer and integer");
3526         }
3527       break;
3528
3529     case UNORDERED_EXPR:
3530     case ORDERED_EXPR:
3531     case UNLT_EXPR:
3532     case UNLE_EXPR:
3533     case UNGT_EXPR:
3534     case UNGE_EXPR:
3535     case UNEQ_EXPR:
3536       build_type = integer_type_node;
3537       if (code0 != REAL_TYPE || code1 != REAL_TYPE)
3538         {
3539           error ("unordered comparison on non-floating point argument");
3540           return error_mark_node;
3541         }
3542       common = 1;
3543       break;
3544
3545     default:
3546       break;
3547     }
3548
3549   if (((code0 == INTEGER_TYPE || code0 == REAL_TYPE || code0 == COMPLEX_TYPE)
3550        && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
3551            || code1 == COMPLEX_TYPE)))
3552     arithmetic_types_p = 1;
3553   else
3554     {
3555       arithmetic_types_p = 0;
3556       /* Vector arithmetic is only allowed when both sides are vectors.  */
3557       if (code0 == VECTOR_TYPE && code1 == VECTOR_TYPE)
3558         {
3559           if (!tree_int_cst_equal (TYPE_SIZE (type0), TYPE_SIZE (type1))
3560               || !same_scalar_type_ignoring_signedness (TREE_TYPE (type0),
3561                                                         TREE_TYPE (type1)))
3562             {
3563               binary_op_error (code, type0, type1);
3564               return error_mark_node;
3565             }
3566           arithmetic_types_p = 1;
3567         }
3568     }
3569   /* Determine the RESULT_TYPE, if it is not already known.  */
3570   if (!result_type
3571       && arithmetic_types_p
3572       && (shorten || common || short_compare))
3573     result_type = common_type (type0, type1);
3574
3575   if (!result_type)
3576     {
3577       error ("invalid operands of types %qT and %qT to binary %qO",
3578              TREE_TYPE (orig_op0), TREE_TYPE (orig_op1), code);
3579       return error_mark_node;
3580     }
3581
3582   /* If we're in a template, the only thing we need to know is the
3583      RESULT_TYPE.  */
3584   if (processing_template_decl)
3585     {
3586       /* Since the middle-end checks the type when doing a build2, we
3587          need to build the tree in pieces.  This built tree will never
3588          get out of the front-end as we replace it when instantiating
3589          the template.  */
3590       tree tmp = build2 (resultcode,
3591                          build_type ? build_type : result_type,
3592                          NULL_TREE, op1);
3593       TREE_OPERAND (tmp, 0) = op0;
3594       return tmp;
3595     }
3596
3597   if (arithmetic_types_p)
3598     {
3599       int none_complex = (code0 != COMPLEX_TYPE && code1 != COMPLEX_TYPE);
3600
3601       /* For certain operations (which identify themselves by shorten != 0)
3602          if both args were extended from the same smaller type,
3603          do the arithmetic in that type and then extend.
3604
3605          shorten !=0 and !=1 indicates a bitwise operation.
3606          For them, this optimization is safe only if
3607          both args are zero-extended or both are sign-extended.
3608          Otherwise, we might change the result.
3609          Eg, (short)-1 | (unsigned short)-1 is (int)-1
3610          but calculated in (unsigned short) it would be (unsigned short)-1.  */
3611
3612       if (shorten && none_complex)
3613         {
3614           int unsigned0, unsigned1;
3615           tree arg0 = get_narrower (op0, &unsigned0);
3616           tree arg1 = get_narrower (op1, &unsigned1);
3617           /* UNS is 1 if the operation to be done is an unsigned one.  */
3618           int uns = TYPE_UNSIGNED (result_type);
3619           tree type;
3620
3621           final_type = result_type;
3622
3623           /* Handle the case that OP0 does not *contain* a conversion
3624              but it *requires* conversion to FINAL_TYPE.  */
3625
3626           if (op0 == arg0 && TREE_TYPE (op0) != final_type)
3627             unsigned0 = TYPE_UNSIGNED (TREE_TYPE (op0));
3628           if (op1 == arg1 && TREE_TYPE (op1) != final_type)
3629             unsigned1 = TYPE_UNSIGNED (TREE_TYPE (op1));
3630
3631           /* Now UNSIGNED0 is 1 if ARG0 zero-extends to FINAL_TYPE.  */
3632
3633           /* For bitwise operations, signedness of nominal type
3634              does not matter.  Consider only how operands were extended.  */
3635           if (shorten == -1)
3636             uns = unsigned0;
3637
3638           /* Note that in all three cases below we refrain from optimizing
3639              an unsigned operation on sign-extended args.
3640              That would not be valid.  */
3641
3642           /* Both args variable: if both extended in same way
3643              from same width, do it in that width.
3644              Do it unsigned if args were zero-extended.  */
3645           if ((TYPE_PRECISION (TREE_TYPE (arg0))
3646                < TYPE_PRECISION (result_type))
3647               && (TYPE_PRECISION (TREE_TYPE (arg1))
3648                   == TYPE_PRECISION (TREE_TYPE (arg0)))
3649               && unsigned0 == unsigned1
3650               && (unsigned0 || !uns))
3651             result_type = c_common_signed_or_unsigned_type
3652               (unsigned0, common_type (TREE_TYPE (arg0), TREE_TYPE (arg1)));
3653           else if (TREE_CODE (arg0) == INTEGER_CST
3654                    && (unsigned1 || !uns)
3655                    && (TYPE_PRECISION (TREE_TYPE (arg1))
3656                        < TYPE_PRECISION (result_type))
3657                    && (type = c_common_signed_or_unsigned_type
3658                        (unsigned1, TREE_TYPE (arg1)),
3659                        int_fits_type_p (arg0, type)))
3660             result_type = type;
3661           else if (TREE_CODE (arg1) == INTEGER_CST
3662                    && (unsigned0 || !uns)
3663                    && (TYPE_PRECISION (TREE_TYPE (arg0))
3664                        < TYPE_PRECISION (result_type))
3665                    && (type = c_common_signed_or_unsigned_type
3666                        (unsigned0, TREE_TYPE (arg0)),
3667                        int_fits_type_p (arg1, type)))
3668             result_type = type;
3669         }
3670
3671       /* Shifts can be shortened if shifting right.  */
3672
3673       if (short_shift)
3674         {
3675           int unsigned_arg;
3676           tree arg0 = get_narrower (op0, &unsigned_arg);
3677
3678           final_type = result_type;
3679
3680           if (arg0 == op0 && final_type == TREE_TYPE (op0))
3681             unsigned_arg = TYPE_UNSIGNED (TREE_TYPE (op0));
3682
3683           if (TYPE_PRECISION (TREE_TYPE (arg0)) < TYPE_PRECISION (result_type)
3684               /* We can shorten only if the shift count is less than the
3685                  number of bits in the smaller type size.  */
3686               && compare_tree_int (op1, TYPE_PRECISION (TREE_TYPE (arg0))) < 0
3687               /* If arg is sign-extended and then unsigned-shifted,
3688                  we can simulate this with a signed shift in arg's type
3689                  only if the extended result is at least twice as wide
3690                  as the arg.  Otherwise, the shift could use up all the
3691                  ones made by sign-extension and bring in zeros.
3692                  We can't optimize that case at all, but in most machines
3693                  it never happens because available widths are 2**N.  */
3694               && (!TYPE_UNSIGNED (final_type)
3695                   || unsigned_arg
3696                   || (((unsigned) 2 * TYPE_PRECISION (TREE_TYPE (arg0)))
3697                       <= TYPE_PRECISION (result_type))))
3698             {
3699               /* Do an unsigned shift if the operand was zero-extended.  */
3700               result_type
3701                 = c_common_signed_or_unsigned_type (unsigned_arg,
3702                                                     TREE_TYPE (arg0));
3703               /* Convert value-to-be-shifted to that type.  */
3704               if (TREE_TYPE (op0) != result_type)
3705                 op0 = cp_convert (result_type, op0);
3706               converted = 1;
3707             }
3708         }
3709
3710       /* Comparison operations are shortened too but differently.
3711          They identify themselves by setting short_compare = 1.  */
3712
3713       if (short_compare)
3714         {
3715           /* Don't write &op0, etc., because that would prevent op0
3716              from being kept in a register.
3717              Instead, make copies of the our local variables and
3718              pass the copies by reference, then copy them back afterward.  */
3719           tree xop0 = op0, xop1 = op1, xresult_type = result_type;
3720           enum tree_code xresultcode = resultcode;
3721           tree val
3722             = shorten_compare (&xop0, &xop1, &xresult_type, &xresultcode);
3723           if (val != 0)
3724             return cp_convert (boolean_type_node, val);
3725           op0 = xop0, op1 = xop1;
3726           converted = 1;
3727           resultcode = xresultcode;
3728         }
3729
3730       if ((short_compare || code == MIN_EXPR || code == MAX_EXPR)
3731           && warn_sign_compare
3732           /* Do not warn until the template is instantiated; we cannot
3733              bound the ranges of the arguments until that point.  */
3734           && !processing_template_decl)
3735         {
3736           int op0_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op0));
3737           int op1_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op1));
3738
3739           int unsignedp0, unsignedp1;
3740           tree primop0 = get_narrower (op0, &unsignedp0);
3741           tree primop1 = get_narrower (op1, &unsignedp1);
3742
3743           /* Check for comparison of different enum types.  */
3744           if (TREE_CODE (TREE_TYPE (orig_op0)) == ENUMERAL_TYPE
3745               && TREE_CODE (TREE_TYPE (orig_op1)) == ENUMERAL_TYPE
3746               && TYPE_MAIN_VARIANT (TREE_TYPE (orig_op0))
3747                  != TYPE_MAIN_VARIANT (TREE_TYPE (orig_op1)))
3748             {
3749               warning (0, "comparison between types %q#T and %q#T",
3750                        TREE_TYPE (orig_op0), TREE_TYPE (orig_op1));
3751             }
3752
3753           /* Give warnings for comparisons between signed and unsigned
3754              quantities that may fail.  */
3755           /* Do the checking based on the original operand trees, so that
3756              casts will be considered, but default promotions won't be.  */
3757
3758           /* Do not warn if the comparison is being done in a signed type,
3759              since the signed type will only be chosen if it can represent
3760              all the values of the unsigned type.  */
3761           if (!TYPE_UNSIGNED (result_type))
3762             /* OK */;
3763           /* Do not warn if both operands are unsigned.  */
3764           else if (op0_signed == op1_signed)
3765             /* OK */;
3766           /* Do not warn if the signed quantity is an unsuffixed
3767              integer literal (or some static constant expression
3768              involving such literals or a conditional expression
3769              involving such literals) and it is non-negative.  */
3770           else if ((op0_signed && tree_expr_nonnegative_p (orig_op0))
3771                    || (op1_signed && tree_expr_nonnegative_p (orig_op1)))
3772             /* OK */;
3773           /* Do not warn if the comparison is an equality operation,
3774              the unsigned quantity is an integral constant and it does
3775              not use the most significant bit of result_type.  */
3776           else if ((resultcode == EQ_EXPR || resultcode == NE_EXPR)
3777                    && ((op0_signed && TREE_CODE (orig_op1) == INTEGER_CST
3778                         && int_fits_type_p (orig_op1, c_common_signed_type
3779                                             (result_type)))
3780                         || (op1_signed && TREE_CODE (orig_op0) == INTEGER_CST
3781                             && int_fits_type_p (orig_op0, c_common_signed_type
3782                                                 (result_type)))))
3783             /* OK */;
3784           else
3785             warning (0, "comparison between signed and unsigned integer expressions");
3786
3787           /* Warn if two unsigned values are being compared in a size
3788              larger than their original size, and one (and only one) is the
3789              result of a `~' operator.  This comparison will always fail.
3790
3791              Also warn if one operand is a constant, and the constant does not
3792              have all bits set that are set in the ~ operand when it is
3793              extended.  */
3794
3795           if ((TREE_CODE (primop0) == BIT_NOT_EXPR)
3796               ^ (TREE_CODE (primop1) == BIT_NOT_EXPR))
3797             {
3798               if (TREE_CODE (primop0) == BIT_NOT_EXPR)
3799                 primop0 = get_narrower (TREE_OPERAND (op0, 0), &unsignedp0);
3800               if (TREE_CODE (primop1) == BIT_NOT_EXPR)
3801                 primop1 = get_narrower (TREE_OPERAND (op1, 0), &unsignedp1);
3802
3803               if (host_integerp (primop0, 0) || host_integerp (primop1, 0))
3804                 {
3805                   tree primop;
3806                   HOST_WIDE_INT constant, mask;
3807                   int unsignedp;
3808                   unsigned int bits;
3809
3810                   if (host_integerp (primop0, 0))
3811                     {
3812                       primop = primop1;
3813                       unsignedp = unsignedp1;
3814                       constant = tree_low_cst (primop0, 0);
3815                     }
3816                   else
3817                     {
3818                       primop = primop0;
3819                       unsignedp = unsignedp0;
3820                       constant = tree_low_cst (primop1, 0);
3821                     }
3822
3823                   bits = TYPE_PRECISION (TREE_TYPE (primop));
3824                   if (bits < TYPE_PRECISION (result_type)
3825                       && bits < HOST_BITS_PER_LONG && unsignedp)
3826                     {
3827                       mask = (~ (HOST_WIDE_INT) 0) << bits;
3828                       if ((mask & constant) != mask)
3829                         warning (0, "comparison of promoted ~unsigned with constant");
3830                     }
3831                 }
3832               else if (unsignedp0 && unsignedp1
3833                        && (TYPE_PRECISION (TREE_TYPE (primop0))
3834                            < TYPE_PRECISION (result_type))
3835                        && (TYPE_PRECISION (TREE_TYPE (primop1))
3836                            < TYPE_PRECISION (result_type)))
3837                 warning (0, "comparison of promoted ~unsigned with unsigned");
3838             }
3839         }
3840     }
3841
3842   /* Issue warnings about peculiar, but valid, uses of NULL.  */
3843   if ((orig_op0 == null_node || orig_op1 == null_node)
3844       /* It's reasonable to use pointer values as operands of &&
3845          and ||, so NULL is no exception.  */
3846       && code != TRUTH_ANDIF_EXPR && code != TRUTH_ORIF_EXPR
3847       && ( /* Both are NULL (or 0) and the operation was not a comparison.  */
3848           (null_ptr_cst_p (orig_op0) && null_ptr_cst_p (orig_op1)
3849            && code != EQ_EXPR && code != NE_EXPR)
3850           /* Or if one of OP0 or OP1 is neither a pointer nor NULL.  */
3851           || (!null_ptr_cst_p (orig_op0) && TREE_CODE (TREE_TYPE (op0)) != POINTER_TYPE)
3852           || (!null_ptr_cst_p (orig_op1) && TREE_CODE (TREE_TYPE (op1)) != POINTER_TYPE)))
3853     /* Some sort of arithmetic operation involving NULL was
3854        performed.  Note that pointer-difference and pointer-addition
3855        have already been handled above, and so we don't end up here in
3856        that case.  */
3857     warning (OPT_Wpointer_arith, "NULL used in arithmetic");
3858
3859
3860   /* If CONVERTED is zero, both args will be converted to type RESULT_TYPE.
3861      Then the expression will be built.
3862      It will be given type FINAL_TYPE if that is nonzero;
3863      otherwise, it will be given type RESULT_TYPE.  */
3864   if (! converted)
3865     {
3866       if (TREE_TYPE (op0) != result_type)
3867         op0 = cp_convert_and_check (result_type, op0);
3868       if (TREE_TYPE (op1) != result_type)
3869         op1 = cp_convert_and_check (result_type, op1);
3870
3871       if (op0 == error_mark_node || op1 == error_mark_node)
3872         return error_mark_node;
3873     }
3874
3875   if (build_type == NULL_TREE)
3876     build_type = result_type;
3877
3878   result = build2 (resultcode, build_type, op0, op1);
3879   result = fold_if_not_in_template (result);
3880   if (final_type != 0)
3881     result = cp_convert (final_type, result);
3882
3883   if (TREE_OVERFLOW_P (result)
3884       && !TREE_OVERFLOW_P (op0)
3885       && !TREE_OVERFLOW_P (op1))
3886     overflow_warning (result);
3887
3888   return result;
3889 }
3890 \f
3891 /* Return a tree for the sum or difference (RESULTCODE says which)
3892    of pointer PTROP and integer INTOP.  */
3893
3894 static tree
3895 cp_pointer_int_sum (enum tree_code resultcode, tree ptrop, tree intop)
3896 {
3897   tree res_type = TREE_TYPE (ptrop);
3898
3899   /* pointer_int_sum() uses size_in_bytes() on the TREE_TYPE(res_type)
3900      in certain circumstance (when it's valid to do so).  So we need
3901      to make sure it's complete.  We don't need to check here, if we
3902      can actually complete it at all, as those checks will be done in
3903      pointer_int_sum() anyway.  */
3904   complete_type (TREE_TYPE (res_type));
3905
3906   return pointer_int_sum (resultcode, ptrop,
3907                           fold_if_not_in_template (intop));
3908 }
3909
3910 /* Return a tree for the difference of pointers OP0 and OP1.
3911    The resulting tree has type int.  */
3912
3913 static tree
3914 pointer_diff (tree op0, tree op1, tree ptrtype)
3915 {
3916   tree result;
3917   tree restype = ptrdiff_type_node;
3918   tree target_type = TREE_TYPE (ptrtype);
3919
3920   if (!complete_type_or_else (target_type, NULL_TREE))
3921     return error_mark_node;
3922
3923   if (pedantic || warn_pointer_arith)
3924     {
3925       if (TREE_CODE (target_type) == VOID_TYPE)
3926         pedwarn ("ISO C++ forbids using pointer of type %<void *%> in subtraction");
3927       if (TREE_CODE (target_type) == FUNCTION_TYPE)
3928         pedwarn ("ISO C++ forbids using pointer to a function in subtraction");
3929       if (TREE_CODE (target_type) == METHOD_TYPE)
3930         pedwarn ("ISO C++ forbids using pointer to a method in subtraction");
3931     }
3932
3933   /* First do the subtraction as integers;
3934      then drop through to build the divide operator.  */
3935
3936   op0 = cp_build_binary_op (MINUS_EXPR,
3937                             cp_convert (restype, op0),
3938                             cp_convert (restype, op1));
3939
3940   /* This generates an error if op1 is a pointer to an incomplete type.  */
3941   if (!COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (op1))))
3942     error ("invalid use of a pointer to an incomplete type in pointer arithmetic");
3943
3944   op1 = (TYPE_PTROB_P (ptrtype)
3945          ? size_in_bytes (target_type)
3946          : integer_one_node);
3947
3948   /* Do the division.  */
3949
3950   result = build2 (EXACT_DIV_EXPR, restype, op0, cp_convert (restype, op1));
3951   return fold_if_not_in_template (result);
3952 }
3953 \f
3954 /* Construct and perhaps optimize a tree representation
3955    for a unary operation.  CODE, a tree_code, specifies the operation
3956    and XARG is the operand.  */
3957
3958 tree
3959 build_x_unary_op (enum tree_code code, tree xarg)
3960 {
3961   tree orig_expr = xarg;
3962   tree exp;
3963   int ptrmem = 0;
3964
3965   if (processing_template_decl)
3966     {
3967       if (type_dependent_expression_p (xarg))
3968         return build_min_nt (code, xarg, NULL_TREE);
3969
3970       xarg = build_non_dependent_expr (xarg);
3971     }
3972
3973   exp = NULL_TREE;
3974
3975   /* [expr.unary.op] says:
3976
3977        The address of an object of incomplete type can be taken.
3978
3979      (And is just the ordinary address operator, not an overloaded
3980      "operator &".)  However, if the type is a template
3981      specialization, we must complete the type at this point so that
3982      an overloaded "operator &" will be available if required.  */
3983   if (code == ADDR_EXPR
3984       && TREE_CODE (xarg) != TEMPLATE_ID_EXPR
3985       && ((CLASS_TYPE_P (TREE_TYPE (xarg))
3986            && !COMPLETE_TYPE_P (complete_type (TREE_TYPE (xarg))))
3987           || (TREE_CODE (xarg) == OFFSET_REF)))
3988     /* Don't look for a function.  */;
3989   else
3990     exp = build_new_op (code, LOOKUP_NORMAL, xarg, NULL_TREE, NULL_TREE,
3991                         /*overloaded_p=*/NULL);
3992   if (!exp && code == ADDR_EXPR)
3993     {
3994       /*  A pointer to member-function can be formed only by saying
3995           &X::mf.  */
3996       if (!flag_ms_extensions && TREE_CODE (TREE_TYPE (xarg)) == METHOD_TYPE
3997           && (TREE_CODE (xarg) != OFFSET_REF || !PTRMEM_OK_P (xarg)))
3998         {
3999           if (TREE_CODE (xarg) != OFFSET_REF
4000               || !TYPE_P (TREE_OPERAND (xarg, 0)))
4001             {
4002               error ("invalid use of %qE to form a pointer-to-member-function",
4003                      xarg);
4004               if (TREE_CODE (xarg) != OFFSET_REF)
4005                 inform ("  a qualified-id is required");
4006               return error_mark_node;
4007             }
4008           else
4009             {
4010               error ("parentheses around %qE cannot be used to form a"
4011                      " pointer-to-member-function",
4012                      xarg);
4013               PTRMEM_OK_P (xarg) = 1;
4014             }
4015         }
4016
4017       if (TREE_CODE (xarg) == OFFSET_REF)
4018         {
4019           ptrmem = PTRMEM_OK_P (xarg);
4020
4021           if (!ptrmem && !flag_ms_extensions
4022               && TREE_CODE (TREE_TYPE (TREE_OPERAND (xarg, 1))) == METHOD_TYPE)
4023             {
4024               /* A single non-static member, make sure we don't allow a
4025                  pointer-to-member.  */
4026               xarg = build2 (OFFSET_REF, TREE_TYPE (xarg),
4027                              TREE_OPERAND (xarg, 0),
4028                              ovl_cons (TREE_OPERAND (xarg, 1), NULL_TREE));
4029               PTRMEM_OK_P (xarg) = ptrmem;
4030             }
4031         }
4032       else if (TREE_CODE (xarg) == TARGET_EXPR)
4033         warning (0, "taking address of temporary");
4034       exp = build_unary_op (ADDR_EXPR, xarg, 0);
4035     }
4036
4037   if (processing_template_decl && exp != error_mark_node)
4038     exp = build_min_non_dep (code, exp, orig_expr,
4039                              /*For {PRE,POST}{INC,DEC}REMENT_EXPR*/NULL_TREE);
4040   if (TREE_CODE (exp) == ADDR_EXPR)
4041     PTRMEM_OK_P (exp) = ptrmem;
4042   return exp;
4043 }
4044
4045 /* Like c_common_truthvalue_conversion, but handle pointer-to-member
4046    constants, where a null value is represented by an INTEGER_CST of
4047    -1.  */
4048
4049 tree
4050 cp_truthvalue_conversion (tree expr)
4051 {
4052   tree type = TREE_TYPE (expr);
4053   if (TYPE_PTRMEM_P (type))
4054     return build_binary_op (NE_EXPR, expr, integer_zero_node, 1);
4055   else
4056     return c_common_truthvalue_conversion (expr);
4057 }
4058
4059 /* Just like cp_truthvalue_conversion, but we want a CLEANUP_POINT_EXPR.  */
4060
4061 tree
4062 condition_conversion (tree expr)
4063 {
4064   tree t;
4065   if (processing_template_decl)
4066     return expr;
4067   t = perform_implicit_conversion (boolean_type_node, expr);
4068   t = fold_build_cleanup_point_expr (boolean_type_node, t);
4069   return t;
4070 }
4071
4072 /* Return an ADDR_EXPR giving the address of T.  This function
4073    attempts no optimizations or simplifications; it is a low-level
4074    primitive.  */
4075
4076 tree
4077 build_address (tree t)
4078 {
4079   tree addr;
4080
4081   if (error_operand_p (t) || !cxx_mark_addressable (t))
4082     return error_mark_node;
4083
4084   addr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (t)), t);
4085
4086   return addr;
4087 }
4088
4089 /* Return a NOP_EXPR converting EXPR to TYPE.  */
4090
4091 tree
4092 build_nop (tree type, tree expr)
4093 {
4094   if (type == error_mark_node || error_operand_p (expr))
4095     return expr;
4096   return build1 (NOP_EXPR, type, expr);
4097 }
4098
4099 /* C++: Must handle pointers to members.
4100
4101    Perhaps type instantiation should be extended to handle conversion
4102    from aggregates to types we don't yet know we want?  (Or are those
4103    cases typically errors which should be reported?)
4104
4105    NOCONVERT nonzero suppresses the default promotions
4106    (such as from short to int).  */
4107
4108 tree
4109 build_unary_op (enum tree_code code, tree xarg, int noconvert)
4110 {
4111   /* No default_conversion here.  It causes trouble for ADDR_EXPR.  */
4112   tree arg = xarg;
4113   tree argtype = 0;
4114   const char *errstring = NULL;
4115   tree val;
4116   const char *invalid_op_diag;
4117
4118   if (arg == error_mark_node)
4119     return error_mark_node;
4120
4121   if ((invalid_op_diag
4122        = targetm.invalid_unary_op ((code == UNARY_PLUS_EXPR
4123                                     ? CONVERT_EXPR
4124                                     : code),
4125                                    TREE_TYPE (xarg))))
4126     {
4127       error (invalid_op_diag);
4128       return error_mark_node;
4129     }
4130
4131   switch (code)
4132     {
4133     case UNARY_PLUS_EXPR:
4134     case NEGATE_EXPR:
4135       {
4136         int flags = WANT_ARITH | WANT_ENUM;
4137         /* Unary plus (but not unary minus) is allowed on pointers.  */
4138         if (code == UNARY_PLUS_EXPR)
4139           flags |= WANT_POINTER;
4140         arg = build_expr_type_conversion (flags, arg, true);
4141         if (!arg)
4142           errstring = (code == NEGATE_EXPR
4143                        ? "wrong type argument to unary minus"
4144                        : "wrong type argument to unary plus");
4145         else
4146           {
4147             if (!noconvert && CP_INTEGRAL_TYPE_P (TREE_TYPE (arg)))
4148               arg = perform_integral_promotions (arg);
4149
4150             /* Make sure the result is not an lvalue: a unary plus or minus
4151                expression is always a rvalue.  */
4152             arg = rvalue (arg);
4153           }
4154       }
4155       break;
4156
4157     case BIT_NOT_EXPR:
4158       if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
4159         {
4160           code = CONJ_EXPR;
4161           if (!noconvert)
4162             arg = default_conversion (arg);
4163         }
4164       else if (!(arg = build_expr_type_conversion (WANT_INT | WANT_ENUM
4165                                                    | WANT_VECTOR,
4166                                                    arg, true)))
4167         errstring = "wrong type argument to bit-complement";
4168       else if (!noconvert && CP_INTEGRAL_TYPE_P (TREE_TYPE (arg)))
4169         arg = perform_integral_promotions (arg);
4170       break;
4171
4172     case ABS_EXPR:
4173       if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_ENUM, arg, true)))
4174         errstring = "wrong type argument to abs";
4175       else if (!noconvert)
4176         arg = default_conversion (arg);
4177       break;
4178
4179     case CONJ_EXPR:
4180       /* Conjugating a real value is a no-op, but allow it anyway.  */
4181       if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_ENUM, arg, true)))
4182         errstring = "wrong type argument to conjugation";
4183       else if (!noconvert)
4184         arg = default_conversion (arg);
4185       break;
4186
4187     case TRUTH_NOT_EXPR:
4188       arg = perform_implicit_conversion (boolean_type_node, arg);
4189       val = invert_truthvalue (arg);
4190       if (arg != error_mark_node)
4191         return val;
4192       errstring = "in argument to unary !";
4193       break;
4194
4195     case NOP_EXPR:
4196       break;
4197
4198     case REALPART_EXPR:
4199       if (TREE_CODE (arg) == COMPLEX_CST)
4200         return TREE_REALPART (arg);
4201       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
4202         {
4203           arg = build1 (REALPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg);
4204           return fold_if_not_in_template (arg);
4205         }
4206       else
4207         return arg;
4208
4209     case IMAGPART_EXPR:
4210       if (TREE_CODE (arg) == COMPLEX_CST)
4211         return TREE_IMAGPART (arg);
4212       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
4213         {
4214           arg = build1 (IMAGPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg);
4215           return fold_if_not_in_template (arg);
4216         }
4217       else
4218         return cp_convert (TREE_TYPE (arg), integer_zero_node);
4219
4220     case PREINCREMENT_EXPR:
4221     case POSTINCREMENT_EXPR:
4222     case PREDECREMENT_EXPR:
4223     case POSTDECREMENT_EXPR:
4224       /* Handle complex lvalues (when permitted)
4225          by reduction to simpler cases.  */
4226
4227       val = unary_complex_lvalue (code, arg);
4228       if (val != 0)
4229         return val;
4230
4231       /* Increment or decrement the real part of the value,
4232          and don't change the imaginary part.  */
4233       if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
4234         {
4235           tree real, imag;
4236
4237           arg = stabilize_reference (arg);
4238           real = build_unary_op (REALPART_EXPR, arg, 1);
4239           imag = build_unary_op (IMAGPART_EXPR, arg, 1);
4240           real = build_unary_op (code, real, 1);
4241           if (real == error_mark_node || imag == error_mark_node)
4242             return error_mark_node;
4243           return build2 (COMPLEX_EXPR, TREE_TYPE (arg),
4244                          real, imag);
4245         }
4246
4247       /* Report invalid types.  */
4248
4249       if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_POINTER,
4250                                               arg, true)))
4251         {
4252           if (code == PREINCREMENT_EXPR)
4253             errstring ="no pre-increment operator for type";
4254           else if (code == POSTINCREMENT_EXPR)
4255             errstring ="no post-increment operator for type";
4256           else if (code == PREDECREMENT_EXPR)
4257             errstring ="no pre-decrement operator for type";
4258           else
4259             errstring ="no post-decrement operator for type";
4260           break;
4261         }
4262       else if (arg == error_mark_node)
4263         return error_mark_node;
4264
4265       /* Report something read-only.  */
4266
4267       if (CP_TYPE_CONST_P (TREE_TYPE (arg))
4268           || TREE_READONLY (arg))
4269         readonly_error (arg, ((code == PREINCREMENT_EXPR
4270                                || code == POSTINCREMENT_EXPR)
4271                               ? "increment" : "decrement"));
4272
4273       {
4274         tree inc;
4275         tree declared_type;
4276         tree result_type = TREE_TYPE (arg);
4277
4278         declared_type = unlowered_expr_type (arg);
4279
4280         arg = get_unwidened (arg, 0);
4281         argtype = TREE_TYPE (arg);
4282
4283         /* ARM $5.2.5 last annotation says this should be forbidden.  */
4284         if (TREE_CODE (argtype) == ENUMERAL_TYPE)
4285           pedwarn ((code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
4286                    ? G_("ISO C++ forbids incrementing an enum")
4287                    : G_("ISO C++ forbids decrementing an enum"));
4288
4289         /* Compute the increment.  */
4290
4291         if (TREE_CODE (argtype) == POINTER_TYPE)
4292           {
4293             tree type = complete_type (TREE_TYPE (argtype));
4294
4295             if (!COMPLETE_OR_VOID_TYPE_P (type))
4296               error (((code == PREINCREMENT_EXPR
4297                        || code == POSTINCREMENT_EXPR))
4298                      ? G_("cannot increment a pointer to incomplete type %qT")
4299                      : G_("cannot decrement a pointer to incomplete type %qT"),
4300                       TREE_TYPE (argtype));
4301             else if ((pedantic || warn_pointer_arith)
4302                      && !TYPE_PTROB_P (argtype))
4303               pedwarn ((code == PREINCREMENT_EXPR
4304                          || code == POSTINCREMENT_EXPR)
4305                        ? G_("ISO C++ forbids incrementing a pointer of type %qT")
4306                        : G_("ISO C++ forbids decrementing a pointer of type %qT"),
4307                         argtype);
4308             inc = cxx_sizeof_nowarn (TREE_TYPE (argtype));
4309           }
4310         else
4311           inc = integer_one_node;
4312
4313         inc = cp_convert (argtype, inc);
4314
4315         /* Complain about anything else that is not a true lvalue.  */
4316         if (!lvalue_or_else (arg, ((code == PREINCREMENT_EXPR
4317                                     || code == POSTINCREMENT_EXPR)
4318                                    ? lv_increment : lv_decrement)))
4319           return error_mark_node;
4320
4321         /* Forbid using -- on `bool'.  */
4322         if (same_type_p (declared_type, boolean_type_node))
4323           {
4324             if (code == POSTDECREMENT_EXPR || code == PREDECREMENT_EXPR)
4325               {
4326                 error ("invalid use of %<--%> on bool variable %qD", arg);
4327                 return error_mark_node;
4328               }
4329             val = boolean_increment (code, arg);
4330           }
4331         else
4332           val = build2 (code, TREE_TYPE (arg), arg, inc);
4333
4334         TREE_SIDE_EFFECTS (val) = 1;
4335         return cp_convert (result_type, val);
4336       }
4337
4338     case ADDR_EXPR:
4339       /* Note that this operation never does default_conversion
4340          regardless of NOCONVERT.  */
4341
4342       argtype = lvalue_type (arg);
4343
4344       if (TREE_CODE (arg) == OFFSET_REF)
4345         goto offset_ref;
4346
4347       if (TREE_CODE (argtype) == REFERENCE_TYPE)
4348         {
4349           tree type = build_pointer_type (TREE_TYPE (argtype));
4350           arg = build1 (CONVERT_EXPR, type, arg);
4351           return arg;
4352         }
4353       else if (pedantic && DECL_MAIN_P (arg))
4354         /* ARM $3.4 */
4355         pedwarn ("ISO C++ forbids taking address of function %<::main%>");
4356
4357       /* Let &* cancel out to simplify resulting code.  */
4358       if (TREE_CODE (arg) == INDIRECT_REF)
4359         {
4360           /* We don't need to have `current_class_ptr' wrapped in a
4361              NON_LVALUE_EXPR node.  */
4362           if (arg == current_class_ref)
4363             return current_class_ptr;
4364
4365           arg = TREE_OPERAND (arg, 0);
4366           if (TREE_CODE (TREE_TYPE (arg)) == REFERENCE_TYPE)
4367             {
4368               tree type = build_pointer_type (TREE_TYPE (TREE_TYPE (arg)));
4369               arg = build1 (CONVERT_EXPR, type, arg);
4370             }
4371           else
4372             /* Don't let this be an lvalue.  */
4373             arg = rvalue (arg);
4374           return arg;
4375         }
4376
4377       /* Uninstantiated types are all functions.  Taking the
4378          address of a function is a no-op, so just return the
4379          argument.  */
4380
4381       gcc_assert (TREE_CODE (arg) != IDENTIFIER_NODE
4382                   || !IDENTIFIER_OPNAME_P (arg));
4383
4384       if (TREE_CODE (arg) == COMPONENT_REF && type_unknown_p (arg)
4385           && !really_overloaded_fn (TREE_OPERAND (arg, 1)))
4386         {
4387           /* They're trying to take the address of a unique non-static
4388              member function.  This is ill-formed (except in MS-land),
4389              but let's try to DTRT.
4390              Note: We only handle unique functions here because we don't
4391              want to complain if there's a static overload; non-unique
4392              cases will be handled by instantiate_type.  But we need to
4393              handle this case here to allow casts on the resulting PMF.
4394              We could defer this in non-MS mode, but it's easier to give
4395              a useful error here.  */
4396
4397           /* Inside constant member functions, the `this' pointer
4398              contains an extra const qualifier.  TYPE_MAIN_VARIANT
4399              is used here to remove this const from the diagnostics
4400              and the created OFFSET_REF.  */
4401           tree base = TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg, 0)));
4402           tree fn = get_first_fn (TREE_OPERAND (arg, 1));
4403           mark_used (fn);
4404
4405           if (! flag_ms_extensions)
4406             {
4407               tree name = DECL_NAME (fn);
4408               if (current_class_type
4409                   && TREE_OPERAND (arg, 0) == current_class_ref)
4410                 /* An expression like &memfn.  */
4411                 pedwarn ("ISO C++ forbids taking the address of an unqualified"
4412                          " or parenthesized non-static member function to form"
4413                          " a pointer to member function.  Say %<&%T::%D%>",
4414                          base, name);
4415               else
4416                 pedwarn ("ISO C++ forbids taking the address of a bound member"
4417                          " function to form a pointer to member function."
4418                          "  Say %<&%T::%D%>",
4419                          base, name);
4420             }
4421           arg = build_offset_ref (base, fn, /*address_p=*/true);
4422         }
4423
4424     offset_ref:
4425       if (type_unknown_p (arg))
4426         return build1 (ADDR_EXPR, unknown_type_node, arg);
4427
4428       /* Handle complex lvalues (when permitted)
4429          by reduction to simpler cases.  */
4430       val = unary_complex_lvalue (code, arg);
4431       if (val != 0)
4432         return val;
4433
4434       switch (TREE_CODE (arg))
4435         {
4436         case NOP_EXPR:
4437         case CONVERT_EXPR:
4438         case FLOAT_EXPR:
4439         case FIX_TRUNC_EXPR:
4440           if (! lvalue_p (arg) && pedantic)
4441             pedwarn ("ISO C++ forbids taking the address of a cast to a non-lvalue expression");
4442           break;
4443
4444         case BASELINK:
4445           arg = BASELINK_FUNCTIONS (arg);
4446           /* Fall through.  */
4447
4448         case OVERLOAD:
4449           arg = OVL_CURRENT (arg);
4450           break;
4451
4452         case OFFSET_REF:
4453           /* Turn a reference to a non-static data member into a
4454              pointer-to-member.  */
4455           {
4456             tree type;
4457             tree t;
4458
4459             if (!PTRMEM_OK_P (arg))
4460               return build_unary_op (code, arg, 0);
4461
4462             t = TREE_OPERAND (arg, 1);
4463             if (TREE_CODE (TREE_TYPE (t)) == REFERENCE_TYPE)
4464               {
4465                 error ("cannot create pointer to reference member %qD", t);
4466                 return error_mark_node;
4467               }
4468
4469             type = build_ptrmem_type (context_for_name_lookup (t),
4470                                       TREE_TYPE (t));
4471             t = make_ptrmem_cst (type, TREE_OPERAND (arg, 1));
4472             return t;
4473           }
4474
4475         default:
4476           break;
4477         }
4478
4479       /* Anything not already handled and not a true memory reference
4480          is an error.  */
4481       if (TREE_CODE (argtype) != FUNCTION_TYPE
4482           && TREE_CODE (argtype) != METHOD_TYPE
4483           && TREE_CODE (arg) != OFFSET_REF
4484           && !lvalue_or_else (arg, lv_addressof))
4485         return error_mark_node;
4486
4487       if (argtype != error_mark_node)
4488         argtype = build_pointer_type (argtype);
4489
4490       /* In a template, we are processing a non-dependent expression
4491          so we can just form an ADDR_EXPR with the correct type.  */
4492       if (processing_template_decl)
4493         {
4494           val = build_address (arg);
4495           if (TREE_CODE (arg) == OFFSET_REF)
4496             PTRMEM_OK_P (val) = PTRMEM_OK_P (arg);
4497           return val;
4498         }
4499
4500       if (TREE_CODE (arg) != COMPONENT_REF)
4501         {
4502           val = build_address (arg);
4503           if (TREE_CODE (arg) == OFFSET_REF)
4504             PTRMEM_OK_P (val) = PTRMEM_OK_P (arg);
4505         }
4506       else if (TREE_CODE (TREE_OPERAND (arg, 1)) == BASELINK)
4507         {
4508           tree fn = BASELINK_FUNCTIONS (TREE_OPERAND (arg, 1));
4509
4510           /* We can only get here with a single static member
4511              function.  */
4512           gcc_assert (TREE_CODE (fn) == FUNCTION_DECL
4513                       && DECL_STATIC_FUNCTION_P (fn));
4514           mark_used (fn);
4515           val = build_address (fn);
4516           if (TREE_SIDE_EFFECTS (TREE_OPERAND (arg, 0)))
4517             /* Do not lose object's side effects.  */
4518             val = build2 (COMPOUND_EXPR, TREE_TYPE (val),
4519                           TREE_OPERAND (arg, 0), val);
4520         }
4521       else if (DECL_C_BIT_FIELD (TREE_OPERAND (arg, 1)))
4522         {
4523           error ("attempt to take address of bit-field structure member %qD",
4524                  TREE_OPERAND (arg, 1));
4525           return error_mark_node;
4526         }
4527       else
4528         {
4529           tree object = TREE_OPERAND (arg, 0);
4530           tree field = TREE_OPERAND (arg, 1);
4531           gcc_assert (same_type_ignoring_top_level_qualifiers_p
4532                       (TREE_TYPE (object), decl_type_context (field)));
4533           val = build_address (arg);
4534         }
4535
4536       if (TREE_CODE (argtype) == POINTER_TYPE
4537           && TREE_CODE (TREE_TYPE (argtype)) == METHOD_TYPE)
4538         {
4539           build_ptrmemfunc_type (argtype);
4540           val = build_ptrmemfunc (argtype, val, 0,
4541                                   /*c_cast_p=*/false);
4542         }
4543
4544       return val;
4545
4546     default:
4547       break;
4548     }
4549
4550   if (!errstring)
4551     {
4552       if (argtype == 0)
4553         argtype = TREE_TYPE (arg);
4554       return fold_if_not_in_template (build1 (code, argtype, arg));
4555     }
4556
4557   error ("%s", errstring);
4558   return error_mark_node;
4559 }
4560
4561 /* Apply unary lvalue-demanding operator CODE to the expression ARG
4562    for certain kinds of expressions which are not really lvalues
4563    but which we can accept as lvalues.
4564
4565    If ARG is not a kind of expression we can handle, return
4566    NULL_TREE.  */
4567
4568 tree
4569 unary_complex_lvalue (enum tree_code code, tree arg)
4570 {
4571   /* Inside a template, making these kinds of adjustments is
4572      pointless; we are only concerned with the type of the
4573      expression.  */
4574   if (processing_template_decl)
4575     return NULL_TREE;
4576
4577   /* Handle (a, b) used as an "lvalue".  */
4578   if (TREE_CODE (arg) == COMPOUND_EXPR)
4579     {
4580       tree real_result = build_unary_op (code, TREE_OPERAND (arg, 1), 0);
4581       return build2 (COMPOUND_EXPR, TREE_TYPE (real_result),
4582                      TREE_OPERAND (arg, 0), real_result);
4583     }
4584
4585   /* Handle (a ? b : c) used as an "lvalue".  */
4586   if (TREE_CODE (arg) == COND_EXPR
4587       || TREE_CODE (arg) == MIN_EXPR || TREE_CODE (arg) == MAX_EXPR)
4588     return rationalize_conditional_expr (code, arg);
4589
4590   /* Handle (a = b), (++a), and (--a) used as an "lvalue".  */
4591   if (TREE_CODE (arg) == MODIFY_EXPR
4592       || TREE_CODE (arg) == PREINCREMENT_EXPR
4593       || TREE_CODE (arg) == PREDECREMENT_EXPR)
4594     {
4595       tree lvalue = TREE_OPERAND (arg, 0);
4596       if (TREE_SIDE_EFFECTS (lvalue))
4597         {
4598           lvalue = stabilize_reference (lvalue);
4599           arg = build2 (TREE_CODE (arg), TREE_TYPE (arg),
4600                         lvalue, TREE_OPERAND (arg, 1));
4601         }
4602       return unary_complex_lvalue
4603         (code, build2 (COMPOUND_EXPR, TREE_TYPE (lvalue), arg, lvalue));
4604     }
4605
4606   if (code != ADDR_EXPR)
4607     return NULL_TREE;
4608
4609   /* Handle (a = b) used as an "lvalue" for `&'.  */
4610   if (TREE_CODE (arg) == MODIFY_EXPR
4611       || TREE_CODE (arg) == INIT_EXPR)
4612     {
4613       tree real_result = build_unary_op (code, TREE_OPERAND (arg, 0), 0);
4614       arg = build2 (COMPOUND_EXPR, TREE_TYPE (real_result),
4615                     arg, real_result);
4616       TREE_NO_WARNING (arg) = 1;
4617       return arg;
4618     }
4619
4620   if (TREE_CODE (TREE_TYPE (arg)) == FUNCTION_TYPE
4621       || TREE_CODE (TREE_TYPE (arg)) == METHOD_TYPE
4622       || TREE_CODE (arg) == OFFSET_REF)
4623     return NULL_TREE;
4624
4625   /* We permit compiler to make function calls returning
4626      objects of aggregate type look like lvalues.  */
4627   {
4628     tree targ = arg;
4629
4630     if (TREE_CODE (targ) == SAVE_EXPR)
4631       targ = TREE_OPERAND (targ, 0);
4632
4633     if (TREE_CODE (targ) == CALL_EXPR && IS_AGGR_TYPE (TREE_TYPE (targ)))
4634       {
4635         if (TREE_CODE (arg) == SAVE_EXPR)
4636           targ = arg;
4637         else
4638           targ = build_cplus_new (TREE_TYPE (arg), arg);
4639         return build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (arg)), targ);
4640       }
4641
4642     if (TREE_CODE (arg) == SAVE_EXPR && TREE_CODE (targ) == INDIRECT_REF)
4643       return build3 (SAVE_EXPR, build_pointer_type (TREE_TYPE (arg)),
4644                      TREE_OPERAND (targ, 0), current_function_decl, NULL);
4645   }
4646
4647   /* Don't let anything else be handled specially.  */
4648   return NULL_TREE;
4649 }
4650 \f
4651 /* Mark EXP saying that we need to be able to take the
4652    address of it; it should not be allocated in a register.
4653    Value is true if successful.
4654
4655    C++: we do not allow `current_class_ptr' to be addressable.  */
4656
4657 bool
4658 cxx_mark_addressable (tree exp)
4659 {
4660   tree x = exp;
4661
4662   while (1)
4663     switch (TREE_CODE (x))
4664       {
4665       case ADDR_EXPR:
4666       case COMPONENT_REF:
4667       case ARRAY_REF:
4668       case REALPART_EXPR:
4669       case IMAGPART_EXPR:
4670         x = TREE_OPERAND (x, 0);
4671         break;
4672
4673       case PARM_DECL:
4674         if (x == current_class_ptr)
4675           {
4676             error ("cannot take the address of %<this%>, which is an rvalue expression");
4677             TREE_ADDRESSABLE (x) = 1; /* so compiler doesn't die later.  */
4678             return true;
4679           }
4680         /* Fall through.  */
4681
4682       case VAR_DECL:
4683         /* Caller should not be trying to mark initialized
4684            constant fields addressable.  */
4685         gcc_assert (DECL_LANG_SPECIFIC (x) == 0
4686                     || DECL_IN_AGGR_P (x) == 0
4687                     || TREE_STATIC (x)
4688                     || DECL_EXTERNAL (x));
4689         /* Fall through.  */
4690
4691       case CONST_DECL:
4692       case RESULT_DECL:
4693         if (DECL_REGISTER (x) && !TREE_ADDRESSABLE (x)
4694             && !DECL_ARTIFICIAL (x))
4695           {
4696             if (TREE_CODE (x) == VAR_DECL && DECL_HARD_REGISTER (x))
4697               {
4698                 error
4699                   ("address of explicit register variable %qD requested", x);
4700                 return false;
4701               }
4702             else if (extra_warnings)
4703               warning
4704                 (OPT_Wextra, "address requested for %qD, which is declared %<register%>", x);
4705           }
4706         TREE_ADDRESSABLE (x) = 1;
4707         return true;
4708
4709       case FUNCTION_DECL:
4710         TREE_ADDRESSABLE (x) = 1;
4711         return true;
4712
4713       case CONSTRUCTOR:
4714         TREE_ADDRESSABLE (x) = 1;
4715         return true;
4716
4717       case TARGET_EXPR:
4718         TREE_ADDRESSABLE (x) = 1;
4719         cxx_mark_addressable (TREE_OPERAND (x, 0));
4720         return true;
4721
4722       default:
4723         return true;
4724     }
4725 }
4726 \f
4727 /* Build and return a conditional expression IFEXP ? OP1 : OP2.  */
4728
4729 tree
4730 build_x_conditional_expr (tree ifexp, tree op1, tree op2)
4731 {
4732   tree orig_ifexp = ifexp;
4733   tree orig_op1 = op1;
4734   tree orig_op2 = op2;
4735   tree expr;
4736
4737   if (processing_template_decl)
4738     {
4739       /* The standard says that the expression is type-dependent if
4740          IFEXP is type-dependent, even though the eventual type of the
4741          expression doesn't dependent on IFEXP.  */
4742       if (type_dependent_expression_p (ifexp)
4743           /* As a GNU extension, the middle operand may be omitted.  */
4744           || (op1 && type_dependent_expression_p (op1))
4745           || type_dependent_expression_p (op2))
4746         return build_min_nt (COND_EXPR, ifexp, op1, op2);
4747       ifexp = build_non_dependent_expr (ifexp);
4748       if (op1)
4749         op1 = build_non_dependent_expr (op1);
4750       op2 = build_non_dependent_expr (op2);
4751     }
4752
4753   expr = build_conditional_expr (ifexp, op1, op2);
4754   if (processing_template_decl && expr != error_mark_node)
4755     return build_min_non_dep (COND_EXPR, expr,
4756                               orig_ifexp, orig_op1, orig_op2);
4757   return expr;
4758 }
4759 \f
4760 /* Given a list of expressions, return a compound expression
4761    that performs them all and returns the value of the last of them.  */
4762
4763 tree build_x_compound_expr_from_list (tree list, const char *msg)
4764 {
4765   tree expr = TREE_VALUE (list);
4766
4767   if (TREE_CHAIN (list))
4768     {
4769       if (msg)
4770         pedwarn ("%s expression list treated as compound expression", msg);
4771
4772       for (list = TREE_CHAIN (list); list; list = TREE_CHAIN (list))
4773         expr = build_x_compound_expr (expr, TREE_VALUE (list));
4774     }
4775
4776   return expr;
4777 }
4778
4779 /* Handle overloading of the ',' operator when needed.  */
4780
4781 tree
4782 build_x_compound_expr (tree op1, tree op2)
4783 {
4784   tree result;
4785   tree orig_op1 = op1;
4786   tree orig_op2 = op2;
4787
4788   if (processing_template_decl)
4789     {
4790       if (type_dependent_expression_p (op1)
4791           || type_dependent_expression_p (op2))
4792         return build_min_nt (COMPOUND_EXPR, op1, op2);
4793       op1 = build_non_dependent_expr (op1);
4794       op2 = build_non_dependent_expr (op2);
4795     }
4796
4797   result = build_new_op (COMPOUND_EXPR, LOOKUP_NORMAL, op1, op2, NULL_TREE,
4798                          /*overloaded_p=*/NULL);
4799   if (!result)
4800     result = build_compound_expr (op1, op2);
4801
4802   if (processing_template_decl && result != error_mark_node)
4803     return build_min_non_dep (COMPOUND_EXPR, result, orig_op1, orig_op2);
4804
4805   return result;
4806 }
4807
4808 /* Build a compound expression.  */
4809
4810 tree
4811 build_compound_expr (tree lhs, tree rhs)
4812 {
4813   lhs = convert_to_void (lhs, "left-hand operand of comma");
4814
4815   if (lhs == error_mark_node || rhs == error_mark_node)
4816     return error_mark_node;
4817
4818   if (TREE_CODE (rhs) == TARGET_EXPR)
4819     {
4820       /* If the rhs is a TARGET_EXPR, then build the compound
4821          expression inside the target_expr's initializer. This
4822          helps the compiler to eliminate unnecessary temporaries.  */
4823       tree init = TREE_OPERAND (rhs, 1);
4824
4825       init = build2 (COMPOUND_EXPR, TREE_TYPE (init), lhs, init);
4826       TREE_OPERAND (rhs, 1) = init;
4827
4828       return rhs;
4829     }
4830
4831   return build2 (COMPOUND_EXPR, TREE_TYPE (rhs), lhs, rhs);
4832 }
4833
4834 /* Issue a diagnostic message if casting from SRC_TYPE to DEST_TYPE
4835    casts away constness.  DIAG_FN gives the function to call if we
4836    need to issue a diagnostic; if it is NULL, no diagnostic will be
4837    issued.  DESCRIPTION explains what operation is taking place.  */
4838
4839 static void
4840 check_for_casting_away_constness (tree src_type, tree dest_type,
4841                                   void (*diag_fn)(const char *, ...) ATTRIBUTE_GCC_CXXDIAG(1,2),
4842                                   const char *description)
4843 {
4844   if (diag_fn && casts_away_constness (src_type, dest_type))
4845     diag_fn ("%s from type %qT to type %qT casts away constness",
4846              description, src_type, dest_type);
4847 }
4848
4849 /* Convert EXPR (an expression with pointer-to-member type) to TYPE
4850    (another pointer-to-member type in the same hierarchy) and return
4851    the converted expression.  If ALLOW_INVERSE_P is permitted, a
4852    pointer-to-derived may be converted to pointer-to-base; otherwise,
4853    only the other direction is permitted.  If C_CAST_P is true, this
4854    conversion is taking place as part of a C-style cast.  */
4855
4856 tree
4857 convert_ptrmem (tree type, tree expr, bool allow_inverse_p,
4858                 bool c_cast_p)
4859 {
4860   if (TYPE_PTRMEM_P (type))
4861     {
4862       tree delta;
4863
4864       if (TREE_CODE (expr) == PTRMEM_CST)
4865         expr = cplus_expand_constant (expr);
4866       delta = get_delta_difference (TYPE_PTRMEM_CLASS_TYPE (TREE_TYPE (expr)),
4867                                     TYPE_PTRMEM_CLASS_TYPE (type),
4868                                     allow_inverse_p,
4869                                     c_cast_p);
4870       if (!integer_zerop (delta))
4871         {
4872           tree cond, op1, op2;
4873
4874           cond = cp_build_binary_op (EQ_EXPR,
4875                                      expr,
4876                                      build_int_cst (TREE_TYPE (expr), -1));
4877           op1 = build_nop (ptrdiff_type_node, expr);
4878           op2 = cp_build_binary_op (PLUS_EXPR, op1, delta);
4879
4880           expr = fold_build3 (COND_EXPR, ptrdiff_type_node, cond, op1, op2);
4881
4882         }
4883
4884       return build_nop (type, expr);
4885     }
4886   else
4887     return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr,
4888                              allow_inverse_p, c_cast_p);
4889 }
4890
4891 /* If EXPR is an INTEGER_CST and ORIG is an arithmetic constant, return
4892    a version of EXPR that has TREE_OVERFLOW set if it is set in ORIG.
4893    Otherwise, return EXPR unchanged.  */
4894
4895 static tree
4896 ignore_overflows (tree expr, tree orig)
4897 {
4898   if (TREE_CODE (expr) == INTEGER_CST
4899       && CONSTANT_CLASS_P (orig)
4900       && TREE_CODE (orig) != STRING_CST
4901       && TREE_OVERFLOW (expr) != TREE_OVERFLOW (orig))
4902     {
4903       if (!TREE_OVERFLOW (orig))
4904         /* Ensure constant sharing.  */
4905         expr = build_int_cst_wide (TREE_TYPE (expr),
4906                                    TREE_INT_CST_LOW (expr),
4907                                    TREE_INT_CST_HIGH (expr));
4908       else
4909         {
4910           /* Avoid clobbering a shared constant.  */
4911           expr = copy_node (expr);
4912           TREE_OVERFLOW (expr) = TREE_OVERFLOW (orig);
4913         }
4914     }
4915   return expr;
4916 }
4917
4918 /* Perform a static_cast from EXPR to TYPE.  When C_CAST_P is true,
4919    this static_cast is being attempted as one of the possible casts
4920    allowed by a C-style cast.  (In that case, accessibility of base
4921    classes is not considered, and it is OK to cast away
4922    constness.)  Return the result of the cast.  *VALID_P is set to
4923    indicate whether or not the cast was valid.  */
4924
4925 static tree
4926 build_static_cast_1 (tree type, tree expr, bool c_cast_p,
4927                      bool *valid_p)
4928 {
4929   tree intype;
4930   tree result;
4931   tree orig;
4932   void (*diag_fn)(const char*, ...) ATTRIBUTE_GCC_CXXDIAG(1,2);
4933   const char *desc;
4934
4935   /* Assume the cast is valid.  */
4936   *valid_p = true;
4937
4938   intype = TREE_TYPE (expr);
4939
4940   /* Save casted types in the function's used types hash table.  */
4941   used_types_insert (type);
4942
4943   /* Determine what to do when casting away constness.  */
4944   if (c_cast_p)
4945     {
4946       /* C-style casts are allowed to cast away constness.  With
4947          WARN_CAST_QUAL, we still want to issue a warning.  */
4948       diag_fn = warn_cast_qual ? warning0 : NULL;
4949       desc = "cast";
4950     }
4951   else
4952     {
4953       /* A static_cast may not cast away constness.  */
4954       diag_fn = error;
4955       desc = "static_cast";
4956     }
4957
4958   /* [expr.static.cast]
4959
4960      An lvalue of type "cv1 B", where B is a class type, can be cast
4961      to type "reference to cv2 D", where D is a class derived (clause
4962      _class.derived_) from B, if a valid standard conversion from
4963      "pointer to D" to "pointer to B" exists (_conv.ptr_), cv2 is the
4964      same cv-qualification as, or greater cv-qualification than, cv1,
4965      and B is not a virtual base class of D.  */
4966   /* We check this case before checking the validity of "TYPE t =
4967      EXPR;" below because for this case:
4968
4969        struct B {};
4970        struct D : public B { D(const B&); };
4971        extern B& b;
4972        void f() { static_cast<const D&>(b); }
4973
4974      we want to avoid constructing a new D.  The standard is not
4975      completely clear about this issue, but our interpretation is
4976      consistent with other compilers.  */
4977   if (TREE_CODE (type) == REFERENCE_TYPE
4978       && CLASS_TYPE_P (TREE_TYPE (type))
4979       && CLASS_TYPE_P (intype)
4980       && real_lvalue_p (expr)
4981       && DERIVED_FROM_P (intype, TREE_TYPE (type))
4982       && can_convert (build_pointer_type (TYPE_MAIN_VARIANT (intype)),
4983                       build_pointer_type (TYPE_MAIN_VARIANT
4984                                           (TREE_TYPE (type))))
4985       && (c_cast_p
4986           || at_least_as_qualified_p (TREE_TYPE (type), intype)))
4987     {
4988       tree base;
4989
4990       /* There is a standard conversion from "D*" to "B*" even if "B"
4991          is ambiguous or inaccessible.  If this is really a
4992          static_cast, then we check both for inaccessibility and
4993          ambiguity.  However, if this is a static_cast being performed
4994          because the user wrote a C-style cast, then accessibility is
4995          not considered.  */
4996       base = lookup_base (TREE_TYPE (type), intype,
4997                           c_cast_p ? ba_unique : ba_check,
4998                           NULL);
4999
5000       /* Convert from "B*" to "D*".  This function will check that "B"
5001          is not a virtual base of "D".  */
5002       expr = build_base_path (MINUS_EXPR, build_address (expr),
5003                               base, /*nonnull=*/false);
5004       /* Convert the pointer to a reference -- but then remember that
5005          there are no expressions with reference type in C++.  */
5006       return convert_from_reference (build_nop (type, expr));
5007     }
5008
5009   orig = expr;
5010
5011   /* [expr.static.cast]
5012
5013      An expression e can be explicitly converted to a type T using a
5014      static_cast of the form static_cast<T>(e) if the declaration T
5015      t(e);" is well-formed, for some invented temporary variable
5016      t.  */
5017   result = perform_direct_initialization_if_possible (type, expr,
5018                                                       c_cast_p);
5019   if (result)
5020     {
5021       result = convert_from_reference (result);
5022
5023       /* Ignore any integer overflow caused by the cast.  */
5024       result = ignore_overflows (result, orig);
5025
5026       /* [expr.static.cast]
5027
5028          If T is a reference type, the result is an lvalue; otherwise,
5029          the result is an rvalue.  */
5030       if (TREE_CODE (type) != REFERENCE_TYPE)
5031         result = rvalue (result);
5032       return result;
5033     }
5034
5035   /* [expr.static.cast]
5036
5037      Any expression can be explicitly converted to type cv void.  */
5038   if (TREE_CODE (type) == VOID_TYPE)
5039     return convert_to_void (expr, /*implicit=*/NULL);
5040
5041   /* [expr.static.cast]
5042
5043      The inverse of any standard conversion sequence (clause _conv_),
5044      other than the lvalue-to-rvalue (_conv.lval_), array-to-pointer
5045      (_conv.array_), function-to-pointer (_conv.func_), and boolean
5046      (_conv.bool_) conversions, can be performed explicitly using
5047      static_cast subject to the restriction that the explicit
5048      conversion does not cast away constness (_expr.const.cast_), and
5049      the following additional rules for specific cases:  */
5050   /* For reference, the conversions not excluded are: integral
5051      promotions, floating point promotion, integral conversions,
5052      floating point conversions, floating-integral conversions,
5053      pointer conversions, and pointer to member conversions.  */
5054   /* DR 128
5055
5056      A value of integral _or enumeration_ type can be explicitly
5057      converted to an enumeration type.  */
5058   /* The effect of all that is that any conversion between any two
5059      types which are integral, floating, or enumeration types can be
5060      performed.  */
5061   if ((INTEGRAL_TYPE_P (type) || SCALAR_FLOAT_TYPE_P (type))
5062       && (INTEGRAL_TYPE_P (intype) || SCALAR_FLOAT_TYPE_P (intype)))
5063     {
5064       expr = ocp_convert (type, expr, CONV_C_CAST, LOOKUP_NORMAL);
5065
5066       /* Ignore any integer overflow caused by the cast.  */
5067       expr = ignore_overflows (expr, orig);
5068       return expr;
5069     }
5070
5071   if (TYPE_PTR_P (type) && TYPE_PTR_P (intype)
5072       && CLASS_TYPE_P (TREE_TYPE (type))
5073       && CLASS_TYPE_P (TREE_TYPE (intype))
5074       && can_convert (build_pointer_type (TYPE_MAIN_VARIANT
5075                                           (TREE_TYPE (intype))),
5076                       build_pointer_type (TYPE_MAIN_VARIANT
5077                                           (TREE_TYPE (type)))))
5078     {
5079       tree base;
5080
5081       if (!c_cast_p)
5082         check_for_casting_away_constness (intype, type, diag_fn, desc);
5083       base = lookup_base (TREE_TYPE (type), TREE_TYPE (intype),
5084                           c_cast_p ? ba_unique : ba_check,
5085                           NULL);
5086       return build_base_path (MINUS_EXPR, expr, base, /*nonnull=*/false);
5087     }
5088
5089   if ((TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
5090       || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
5091     {
5092       tree c1;
5093       tree c2;
5094       tree t1;
5095       tree t2;
5096
5097       c1 = TYPE_PTRMEM_CLASS_TYPE (intype);
5098       c2 = TYPE_PTRMEM_CLASS_TYPE (type);
5099
5100       if (TYPE_PTRMEM_P (type))
5101         {
5102           t1 = (build_ptrmem_type
5103                 (c1,
5104                  TYPE_MAIN_VARIANT (TYPE_PTRMEM_POINTED_TO_TYPE (intype))));
5105           t2 = (build_ptrmem_type
5106                 (c2,
5107                  TYPE_MAIN_VARIANT (TYPE_PTRMEM_POINTED_TO_TYPE (type))));
5108         }
5109       else
5110         {
5111           t1 = intype;
5112           t2 = type;
5113         }
5114       if (can_convert (t1, t2) || can_convert (t2, t1))
5115         {
5116           if (!c_cast_p)
5117             check_for_casting_away_constness (intype, type, diag_fn,
5118                                               desc);
5119           return convert_ptrmem (type, expr, /*allow_inverse_p=*/1,
5120                                  c_cast_p);
5121         }
5122     }
5123
5124   /* [expr.static.cast]
5125
5126      An rvalue of type "pointer to cv void" can be explicitly
5127      converted to a pointer to object type.  A value of type pointer
5128      to object converted to "pointer to cv void" and back to the
5129      original pointer type will have its original value.  */
5130   if (TREE_CODE (intype) == POINTER_TYPE
5131       && VOID_TYPE_P (TREE_TYPE (intype))
5132       && TYPE_PTROB_P (type))
5133     {
5134       if (!c_cast_p)
5135         check_for_casting_away_constness (intype, type, diag_fn, desc);
5136       return build_nop (type, expr);
5137     }
5138
5139   *valid_p = false;
5140   return error_mark_node;
5141 }
5142
5143 /* Return an expression representing static_cast<TYPE>(EXPR).  */
5144
5145 tree
5146 build_static_cast (tree type, tree expr)
5147 {
5148   tree result;
5149   bool valid_p;
5150
5151   if (type == error_mark_node || expr == error_mark_node)
5152     return error_mark_node;
5153
5154   if (processing_template_decl)
5155     {
5156       expr = build_min (STATIC_CAST_EXPR, type, expr);
5157       /* We don't know if it will or will not have side effects.  */
5158       TREE_SIDE_EFFECTS (expr) = 1;
5159       return convert_from_reference (expr);
5160     }
5161
5162   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
5163      Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
5164   if (TREE_CODE (type) != REFERENCE_TYPE
5165       && TREE_CODE (expr) == NOP_EXPR
5166       && TREE_TYPE (expr) == TREE_TYPE (TREE_OPERAND (expr, 0)))
5167     expr = TREE_OPERAND (expr, 0);
5168
5169   result = build_static_cast_1 (type, expr, /*c_cast_p=*/false, &valid_p);
5170   if (valid_p)
5171     return result;
5172
5173   error ("invalid static_cast from type %qT to type %qT",
5174          TREE_TYPE (expr), type);
5175   return error_mark_node;
5176 }
5177
5178 /* EXPR is an expression with member function or pointer-to-member
5179    function type.  TYPE is a pointer type.  Converting EXPR to TYPE is
5180    not permitted by ISO C++, but we accept it in some modes.  If we
5181    are not in one of those modes, issue a diagnostic.  Return the
5182    converted expression.  */
5183
5184 tree
5185 convert_member_func_to_ptr (tree type, tree expr)
5186 {
5187   tree intype;
5188   tree decl;
5189
5190   intype = TREE_TYPE (expr);
5191   gcc_assert (TYPE_PTRMEMFUNC_P (intype)
5192               || TREE_CODE (intype) == METHOD_TYPE);
5193
5194   if (pedantic || warn_pmf2ptr)
5195     pedwarn ("converting from %qT to %qT", intype, type);
5196
5197   if (TREE_CODE (intype) == METHOD_TYPE)
5198     expr = build_addr_func (expr);
5199   else if (TREE_CODE (expr) == PTRMEM_CST)
5200     expr = build_address (PTRMEM_CST_MEMBER (expr));
5201   else
5202     {
5203       decl = maybe_dummy_object (TYPE_PTRMEM_CLASS_TYPE (intype), 0);
5204       decl = build_address (decl);
5205       expr = get_member_function_from_ptrfunc (&decl, expr);
5206     }
5207
5208   return build_nop (type, expr);
5209 }
5210
5211 /* Return a representation for a reinterpret_cast from EXPR to TYPE.
5212    If C_CAST_P is true, this reinterpret cast is being done as part of
5213    a C-style cast.  If VALID_P is non-NULL, *VALID_P is set to
5214    indicate whether or not reinterpret_cast was valid.  */
5215
5216 static tree
5217 build_reinterpret_cast_1 (tree type, tree expr, bool c_cast_p,
5218                           bool *valid_p)
5219 {
5220   tree intype;
5221
5222   /* Assume the cast is invalid.  */
5223   if (valid_p)
5224     *valid_p = true;
5225
5226   if (type == error_mark_node || error_operand_p (expr))
5227     return error_mark_node;
5228
5229   intype = TREE_TYPE (expr);
5230
5231   /* Save casted types in the function's used types hash table.  */
5232   used_types_insert (type);
5233
5234   /* [expr.reinterpret.cast]
5235      An lvalue expression of type T1 can be cast to the type
5236      "reference to T2" if an expression of type "pointer to T1" can be
5237      explicitly converted to the type "pointer to T2" using a
5238      reinterpret_cast.  */
5239   if (TREE_CODE (type) == REFERENCE_TYPE)
5240     {
5241       if (! real_lvalue_p (expr))
5242         {
5243           error ("invalid cast of an rvalue expression of type "
5244                  "%qT to type %qT",
5245                  intype, type);
5246           return error_mark_node;
5247         }
5248
5249       /* Warn about a reinterpret_cast from "A*" to "B&" if "A" and
5250          "B" are related class types; the reinterpret_cast does not
5251          adjust the pointer.  */
5252       if (TYPE_PTR_P (intype)
5253           && (comptypes (TREE_TYPE (intype), TREE_TYPE (type),
5254                          COMPARE_BASE | COMPARE_DERIVED)))
5255         warning (0, "casting %qT to %qT does not dereference pointer",
5256                  intype, type);
5257
5258       expr = build_unary_op (ADDR_EXPR, expr, 0);
5259       if (expr != error_mark_node)
5260         expr = build_reinterpret_cast_1
5261           (build_pointer_type (TREE_TYPE (type)), expr, c_cast_p,
5262            valid_p);
5263       if (expr != error_mark_node)
5264         expr = build_indirect_ref (expr, 0);
5265       return expr;
5266     }
5267
5268   /* As a G++ extension, we consider conversions from member
5269      functions, and pointers to member functions to
5270      pointer-to-function and pointer-to-void types.  If
5271      -Wno-pmf-conversions has not been specified,
5272      convert_member_func_to_ptr will issue an error message.  */
5273   if ((TYPE_PTRMEMFUNC_P (intype)
5274        || TREE_CODE (intype) == METHOD_TYPE)
5275       && TYPE_PTR_P (type)
5276       && (TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE
5277           || VOID_TYPE_P (TREE_TYPE (type))))
5278     return convert_member_func_to_ptr (type, expr);
5279
5280   /* If the cast is not to a reference type, the lvalue-to-rvalue,
5281      array-to-pointer, and function-to-pointer conversions are
5282      performed.  */
5283   expr = decay_conversion (expr);
5284
5285   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
5286      Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
5287   if (TREE_CODE (expr) == NOP_EXPR
5288       && TREE_TYPE (expr) == TREE_TYPE (TREE_OPERAND (expr, 0)))
5289     expr = TREE_OPERAND (expr, 0);
5290
5291   if (error_operand_p (expr))
5292     return error_mark_node;
5293
5294   intype = TREE_TYPE (expr);
5295
5296   /* [expr.reinterpret.cast]
5297      A pointer can be converted to any integral type large enough to
5298      hold it.  */
5299   if (CP_INTEGRAL_TYPE_P (type) && TYPE_PTR_P (intype))
5300     {
5301       if (TYPE_PRECISION (type) < TYPE_PRECISION (intype))
5302         pedwarn ("cast from %qT to %qT loses precision",
5303                  intype, type);
5304     }
5305   /* [expr.reinterpret.cast]
5306      A value of integral or enumeration type can be explicitly
5307      converted to a pointer.  */
5308   else if (TYPE_PTR_P (type) && INTEGRAL_OR_ENUMERATION_TYPE_P (intype))
5309     /* OK */
5310     ;
5311   else if ((TYPE_PTRFN_P (type) && TYPE_PTRFN_P (intype))
5312            || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
5313     return fold_if_not_in_template (build_nop (type, expr));
5314   else if ((TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
5315            || (TYPE_PTROBV_P (type) && TYPE_PTROBV_P (intype)))
5316     {
5317       tree sexpr = expr;
5318
5319       if (!c_cast_p)
5320         check_for_casting_away_constness (intype, type, error,
5321                                           "reinterpret_cast");
5322       /* Warn about possible alignment problems.  */
5323       if (STRICT_ALIGNMENT && warn_cast_align
5324           && !VOID_TYPE_P (type)
5325           && TREE_CODE (TREE_TYPE (intype)) != FUNCTION_TYPE
5326           && COMPLETE_TYPE_P (TREE_TYPE (type))
5327           && COMPLETE_TYPE_P (TREE_TYPE (intype))
5328           && TYPE_ALIGN (TREE_TYPE (type)) > TYPE_ALIGN (TREE_TYPE (intype)))
5329         warning (0, "cast from %qT to %qT increases required alignment of "
5330                  "target type",
5331                  intype, type);
5332
5333       /* We need to strip nops here, because the front end likes to
5334          create (int *)&a for array-to-pointer decay, instead of &a[0].  */
5335       STRIP_NOPS (sexpr);
5336       if (warn_strict_aliasing <= 2)
5337         strict_aliasing_warning (intype, type, sexpr);
5338
5339       return fold_if_not_in_template (build_nop (type, expr));
5340     }
5341   else if ((TYPE_PTRFN_P (type) && TYPE_PTROBV_P (intype))
5342            || (TYPE_PTRFN_P (intype) && TYPE_PTROBV_P (type)))
5343     {
5344       if (pedantic)
5345         /* Only issue a warning, as we have always supported this
5346            where possible, and it is necessary in some cases.  DR 195
5347            addresses this issue, but as of 2004/10/26 is still in
5348            drafting.  */
5349         warning (0, "ISO C++ forbids casting between pointer-to-function and pointer-to-object");
5350       return fold_if_not_in_template (build_nop (type, expr));
5351     }
5352   else if (TREE_CODE (type) == VECTOR_TYPE)
5353     return fold_if_not_in_template (convert_to_vector (type, expr));
5354   else if (TREE_CODE (intype) == VECTOR_TYPE && INTEGRAL_TYPE_P (type))
5355     return fold_if_not_in_template (convert_to_integer (type, expr));
5356   else
5357     {
5358       if (valid_p)
5359         *valid_p = false;
5360       error ("invalid cast from type %qT to type %qT", intype, type);
5361       return error_mark_node;
5362     }
5363
5364   return cp_convert (type, expr);
5365 }
5366
5367 tree
5368 build_reinterpret_cast (tree type, tree expr)
5369 {
5370   if (type == error_mark_node || expr == error_mark_node)
5371     return error_mark_node;
5372
5373   if (processing_template_decl)
5374     {
5375       tree t = build_min (REINTERPRET_CAST_EXPR, type, expr);
5376
5377       if (!TREE_SIDE_EFFECTS (t)
5378           && type_dependent_expression_p (expr))
5379         /* There might turn out to be side effects inside expr.  */
5380         TREE_SIDE_EFFECTS (t) = 1;
5381       return convert_from_reference (t);
5382     }
5383
5384   return build_reinterpret_cast_1 (type, expr, /*c_cast_p=*/false,
5385                                    /*valid_p=*/NULL);
5386 }
5387
5388 /* Perform a const_cast from EXPR to TYPE.  If the cast is valid,
5389    return an appropriate expression.  Otherwise, return
5390    error_mark_node.  If the cast is not valid, and COMPLAIN is true,
5391    then a diagnostic will be issued.  If VALID_P is non-NULL, we are
5392    performing a C-style cast, its value upon return will indicate
5393    whether or not the conversion succeeded.  */
5394
5395 static tree
5396 build_const_cast_1 (tree dst_type, tree expr, bool complain,
5397                     bool *valid_p)
5398 {
5399   tree src_type;
5400   tree reference_type;
5401
5402   /* Callers are responsible for handling error_mark_node as a
5403      destination type.  */
5404   gcc_assert (dst_type != error_mark_node);
5405   /* In a template, callers should be building syntactic
5406      representations of casts, not using this machinery.  */
5407   gcc_assert (!processing_template_decl);
5408
5409   /* Assume the conversion is invalid.  */
5410   if (valid_p)
5411     *valid_p = false;
5412
5413   if (!POINTER_TYPE_P (dst_type) && !TYPE_PTRMEM_P (dst_type))
5414     {
5415       if (complain)
5416         error ("invalid use of const_cast with type %qT, "
5417                "which is not a pointer, "
5418                "reference, nor a pointer-to-data-member type", dst_type);
5419       return error_mark_node;
5420     }
5421
5422   if (TREE_CODE (TREE_TYPE (dst_type)) == FUNCTION_TYPE)
5423     {
5424       if (complain)
5425         error ("invalid use of const_cast with type %qT, which is a pointer "
5426                "or reference to a function type", dst_type);
5427       return error_mark_node;
5428     }
5429
5430   /* Save casted types in the function's used types hash table.  */
5431   used_types_insert (dst_type);
5432
5433   src_type = TREE_TYPE (expr);
5434   /* Expressions do not really have reference types.  */
5435   if (TREE_CODE (src_type) == REFERENCE_TYPE)
5436     src_type = TREE_TYPE (src_type);
5437
5438   /* [expr.const.cast]
5439
5440      An lvalue of type T1 can be explicitly converted to an lvalue of
5441      type T2 using the cast const_cast<T2&> (where T1 and T2 are object
5442      types) if a pointer to T1 can be explicitly converted to the type
5443      pointer to T2 using a const_cast.  */
5444   if (TREE_CODE (dst_type) == REFERENCE_TYPE)
5445     {
5446       reference_type = dst_type;
5447       if (! real_lvalue_p (expr))
5448         {
5449           if (complain)
5450             error ("invalid const_cast of an rvalue of type %qT to type %qT",
5451                    src_type, dst_type);
5452           return error_mark_node;
5453         }
5454       dst_type = build_pointer_type (TREE_TYPE (dst_type));
5455       src_type = build_pointer_type (src_type);
5456     }
5457   else
5458     {
5459       reference_type = NULL_TREE;
5460       /* If the destination type is not a reference type, the
5461          lvalue-to-rvalue, array-to-pointer, and function-to-pointer
5462          conversions are performed.  */
5463       src_type = type_decays_to (src_type);
5464       if (src_type == error_mark_node)
5465         return error_mark_node;
5466     }
5467
5468   if ((TYPE_PTR_P (src_type) || TYPE_PTRMEM_P (src_type))
5469       && comp_ptr_ttypes_const (dst_type, src_type))
5470     {
5471       if (valid_p)
5472         {
5473           *valid_p = true;
5474           /* This cast is actually a C-style cast.  Issue a warning if
5475              the user is making a potentially unsafe cast.  */
5476           if (warn_cast_qual)
5477             check_for_casting_away_constness (src_type, dst_type,
5478                                               warning0,
5479                                               "cast");
5480         }
5481       if (reference_type)
5482         {
5483           expr = build_unary_op (ADDR_EXPR, expr, 0);
5484           expr = build_nop (reference_type, expr);
5485           return convert_from_reference (expr);
5486         }
5487       else
5488         {
5489           expr = decay_conversion (expr);
5490           /* build_c_cast puts on a NOP_EXPR to make the result not an
5491              lvalue.  Strip such NOP_EXPRs if VALUE is being used in
5492              non-lvalue context.  */
5493           if (TREE_CODE (expr) == NOP_EXPR
5494               && TREE_TYPE (expr) == TREE_TYPE (TREE_OPERAND (expr, 0)))
5495             expr = TREE_OPERAND (expr, 0);
5496           return build_nop (dst_type, expr);
5497         }
5498     }
5499
5500   if (complain)
5501     error ("invalid const_cast from type %qT to type %qT",
5502            src_type, dst_type);
5503   return error_mark_node;
5504 }
5505
5506 tree
5507 build_const_cast (tree type, tree expr)
5508 {
5509   if (type == error_mark_node || error_operand_p (expr))
5510     return error_mark_node;
5511
5512   if (processing_template_decl)
5513     {
5514       tree t = build_min (CONST_CAST_EXPR, type, expr);
5515
5516       if (!TREE_SIDE_EFFECTS (t)
5517           && type_dependent_expression_p (expr))
5518         /* There might turn out to be side effects inside expr.  */
5519         TREE_SIDE_EFFECTS (t) = 1;
5520       return convert_from_reference (t);
5521     }
5522
5523   return build_const_cast_1 (type, expr, /*complain=*/true,
5524                              /*valid_p=*/NULL);
5525 }
5526
5527 /* Build an expression representing an explicit C-style cast to type
5528    TYPE of expression EXPR.  */
5529
5530 tree
5531 build_c_cast (tree type, tree expr)
5532 {
5533   tree value = expr;
5534   tree result;
5535   bool valid_p;
5536
5537   if (type == error_mark_node || error_operand_p (expr))
5538     return error_mark_node;
5539
5540   if (processing_template_decl)
5541     {
5542       tree t = build_min (CAST_EXPR, type,
5543                           tree_cons (NULL_TREE, value, NULL_TREE));
5544       /* We don't know if it will or will not have side effects.  */
5545       TREE_SIDE_EFFECTS (t) = 1;
5546       return convert_from_reference (t);
5547     }
5548
5549   /* Casts to a (pointer to a) specific ObjC class (or 'id' or
5550      'Class') should always be retained, because this information aids
5551      in method lookup.  */
5552   if (objc_is_object_ptr (type)
5553       && objc_is_object_ptr (TREE_TYPE (expr)))
5554     return build_nop (type, expr);
5555
5556   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
5557      Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
5558   if (TREE_CODE (type) != REFERENCE_TYPE
5559       && TREE_CODE (value) == NOP_EXPR
5560       && TREE_TYPE (value) == TREE_TYPE (TREE_OPERAND (value, 0)))
5561     value = TREE_OPERAND (value, 0);
5562
5563   if (TREE_CODE (type) == ARRAY_TYPE)
5564     {
5565       /* Allow casting from T1* to T2[] because Cfront allows it.
5566          NIHCL uses it. It is not valid ISO C++ however.  */
5567       if (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE)
5568         {
5569           pedwarn ("ISO C++ forbids casting to an array type %qT", type);
5570           type = build_pointer_type (TREE_TYPE (type));
5571         }
5572       else
5573         {
5574           error ("ISO C++ forbids casting to an array type %qT", type);
5575           return error_mark_node;
5576         }
5577     }
5578
5579   if (TREE_CODE (type) == FUNCTION_TYPE
5580       || TREE_CODE (type) == METHOD_TYPE)
5581     {
5582       error ("invalid cast to function type %qT", type);
5583       return error_mark_node;
5584     }
5585
5586   /* A C-style cast can be a const_cast.  */
5587   result = build_const_cast_1 (type, value, /*complain=*/false,
5588                                &valid_p);
5589   if (valid_p)
5590     return result;
5591
5592   /* Or a static cast.  */
5593   result = build_static_cast_1 (type, value, /*c_cast_p=*/true,
5594                                 &valid_p);
5595   /* Or a reinterpret_cast.  */
5596   if (!valid_p)
5597     result = build_reinterpret_cast_1 (type, value, /*c_cast_p=*/true,
5598                                        &valid_p);
5599   /* The static_cast or reinterpret_cast may be followed by a
5600      const_cast.  */
5601   if (valid_p
5602       /* A valid cast may result in errors if, for example, a
5603          conversion to am ambiguous base class is required.  */
5604       && !error_operand_p (result))
5605     {
5606       tree result_type;
5607
5608       /* Non-class rvalues always have cv-unqualified type.  */
5609       if (!CLASS_TYPE_P (type))
5610         type = TYPE_MAIN_VARIANT (type);
5611       result_type = TREE_TYPE (result);
5612       if (!CLASS_TYPE_P (result_type))
5613         result_type = TYPE_MAIN_VARIANT (result_type);
5614       /* If the type of RESULT does not match TYPE, perform a
5615          const_cast to make it match.  If the static_cast or
5616          reinterpret_cast succeeded, we will differ by at most
5617          cv-qualification, so the follow-on const_cast is guaranteed
5618          to succeed.  */
5619       if (!same_type_p (non_reference (type), non_reference (result_type)))
5620         {
5621           result = build_const_cast_1 (type, result, false, &valid_p);
5622           gcc_assert (valid_p);
5623         }
5624       return result;
5625     }
5626
5627   return error_mark_node;
5628 }
5629 \f
5630 /* Build an assignment expression of lvalue LHS from value RHS.
5631    MODIFYCODE is the code for a binary operator that we use
5632    to combine the old value of LHS with RHS to get the new value.
5633    Or else MODIFYCODE is NOP_EXPR meaning do a simple assignment.
5634
5635    C++: If MODIFYCODE is INIT_EXPR, then leave references unbashed.  */
5636
5637 tree
5638 build_modify_expr (tree lhs, enum tree_code modifycode, tree rhs)
5639 {
5640   tree result;
5641   tree newrhs = rhs;
5642   tree lhstype = TREE_TYPE (lhs);
5643   tree olhstype = lhstype;
5644   tree olhs = NULL_TREE;
5645   bool plain_assign = (modifycode == NOP_EXPR);
5646
5647   /* Avoid duplicate error messages from operands that had errors.  */
5648   if (error_operand_p (lhs) || error_operand_p (rhs))
5649     return error_mark_node;
5650
5651   /* Handle control structure constructs used as "lvalues".  */
5652   switch (TREE_CODE (lhs))
5653     {
5654       /* Handle --foo = 5; as these are valid constructs in C++.  */
5655     case PREDECREMENT_EXPR:
5656     case PREINCREMENT_EXPR:
5657       if (TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 0)))
5658         lhs = build2 (TREE_CODE (lhs), TREE_TYPE (lhs),
5659                       stabilize_reference (TREE_OPERAND (lhs, 0)),
5660                       TREE_OPERAND (lhs, 1));
5661       return build2 (COMPOUND_EXPR, lhstype,
5662                      lhs,
5663                      build_modify_expr (TREE_OPERAND (lhs, 0),
5664                                         modifycode, rhs));
5665
5666       /* Handle (a, b) used as an "lvalue".  */
5667     case COMPOUND_EXPR:
5668       newrhs = build_modify_expr (TREE_OPERAND (lhs, 1),
5669                                   modifycode, rhs);
5670       if (newrhs == error_mark_node)
5671         return error_mark_node;
5672       return build2 (COMPOUND_EXPR, lhstype,
5673                      TREE_OPERAND (lhs, 0), newrhs);
5674
5675     case MODIFY_EXPR:
5676       if (TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 0)))
5677         lhs = build2 (TREE_CODE (lhs), TREE_TYPE (lhs),
5678                       stabilize_reference (TREE_OPERAND (lhs, 0)),
5679                       TREE_OPERAND (lhs, 1));
5680       newrhs = build_modify_expr (TREE_OPERAND (lhs, 0), modifycode, rhs);
5681       if (newrhs == error_mark_node)
5682         return error_mark_node;
5683       return build2 (COMPOUND_EXPR, lhstype, lhs, newrhs);
5684
5685     case MIN_EXPR:
5686     case MAX_EXPR:
5687       /* MIN_EXPR and MAX_EXPR are currently only permitted as lvalues,
5688          when neither operand has side-effects.  */
5689       if (!lvalue_or_else (lhs, lv_assign))
5690         return error_mark_node;
5691
5692       gcc_assert (!TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 0))
5693                   && !TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 1)));
5694
5695       lhs = build3 (COND_EXPR, TREE_TYPE (lhs),
5696                     build2 (TREE_CODE (lhs) == MIN_EXPR ? LE_EXPR : GE_EXPR,
5697                             boolean_type_node,
5698                             TREE_OPERAND (lhs, 0),
5699                             TREE_OPERAND (lhs, 1)),
5700                     TREE_OPERAND (lhs, 0),
5701                     TREE_OPERAND (lhs, 1));
5702       /* Fall through.  */
5703
5704       /* Handle (a ? b : c) used as an "lvalue".  */
5705     case COND_EXPR:
5706       {
5707         /* Produce (a ? (b = rhs) : (c = rhs))
5708            except that the RHS goes through a save-expr
5709            so the code to compute it is only emitted once.  */
5710         tree cond;
5711         tree preeval = NULL_TREE;
5712
5713         if (VOID_TYPE_P (TREE_TYPE (rhs)))
5714           {
5715             error ("void value not ignored as it ought to be");
5716             return error_mark_node;
5717           }
5718
5719         rhs = stabilize_expr (rhs, &preeval);
5720
5721         /* Check this here to avoid odd errors when trying to convert
5722            a throw to the type of the COND_EXPR.  */
5723         if (!lvalue_or_else (lhs, lv_assign))
5724           return error_mark_node;
5725
5726         cond = build_conditional_expr
5727           (TREE_OPERAND (lhs, 0),
5728            build_modify_expr (TREE_OPERAND (lhs, 1),
5729                               modifycode, rhs),
5730            build_modify_expr (TREE_OPERAND (lhs, 2),
5731                               modifycode, rhs));
5732
5733         if (cond == error_mark_node)
5734           return cond;
5735         /* Make sure the code to compute the rhs comes out
5736            before the split.  */
5737         if (preeval)
5738           cond = build2 (COMPOUND_EXPR, TREE_TYPE (lhs), preeval, cond);
5739         return cond;
5740       }
5741
5742     default:
5743       break;
5744     }
5745
5746   if (modifycode == INIT_EXPR)
5747     {
5748       if (TREE_CODE (rhs) == CONSTRUCTOR)
5749         {
5750           if (! same_type_p (TREE_TYPE (rhs), lhstype))
5751             /* Call convert to generate an error; see PR 11063.  */
5752             rhs = convert (lhstype, rhs);
5753           result = build2 (INIT_EXPR, lhstype, lhs, rhs);
5754           TREE_SIDE_EFFECTS (result) = 1;
5755           return result;
5756         }
5757       else if (! IS_AGGR_TYPE (lhstype))
5758         /* Do the default thing.  */;
5759       else
5760         {
5761           result = build_special_member_call (lhs, complete_ctor_identifier,
5762                                               build_tree_list (NULL_TREE, rhs),
5763                                               lhstype, LOOKUP_NORMAL);
5764           if (result == NULL_TREE)
5765             return error_mark_node;
5766           return result;
5767         }
5768     }
5769   else
5770     {
5771       lhs = require_complete_type (lhs);
5772       if (lhs == error_mark_node)
5773         return error_mark_node;
5774
5775       if (modifycode == NOP_EXPR)
5776         {
5777           /* `operator=' is not an inheritable operator.  */
5778           if (! IS_AGGR_TYPE (lhstype))
5779             /* Do the default thing.  */;
5780           else
5781             {
5782               result = build_new_op (MODIFY_EXPR, LOOKUP_NORMAL,
5783                                      lhs, rhs, make_node (NOP_EXPR),
5784                                      /*overloaded_p=*/NULL);
5785               if (result == NULL_TREE)
5786                 return error_mark_node;
5787               return result;
5788             }
5789           lhstype = olhstype;
5790         }
5791       else
5792         {
5793           /* A binary op has been requested.  Combine the old LHS
5794              value with the RHS producing the value we should actually
5795              store into the LHS.  */
5796
5797           gcc_assert (!PROMOTES_TO_AGGR_TYPE (lhstype, REFERENCE_TYPE));
5798           lhs = stabilize_reference (lhs);
5799           newrhs = cp_build_binary_op (modifycode, lhs, rhs);
5800           if (newrhs == error_mark_node)
5801             {
5802               error ("  in evaluation of %<%Q(%#T, %#T)%>", modifycode,
5803                      TREE_TYPE (lhs), TREE_TYPE (rhs));
5804               return error_mark_node;
5805             }
5806
5807           /* Now it looks like a plain assignment.  */
5808           modifycode = NOP_EXPR;
5809         }
5810       gcc_assert (TREE_CODE (lhstype) != REFERENCE_TYPE);
5811       gcc_assert (TREE_CODE (TREE_TYPE (newrhs)) != REFERENCE_TYPE);
5812     }
5813
5814   /* The left-hand side must be an lvalue.  */
5815   if (!lvalue_or_else (lhs, lv_assign))
5816     return error_mark_node;
5817
5818   /* Warn about modifying something that is `const'.  Don't warn if
5819      this is initialization.  */
5820   if (modifycode != INIT_EXPR
5821       && (TREE_READONLY (lhs) || CP_TYPE_CONST_P (lhstype)
5822           /* Functions are not modifiable, even though they are
5823              lvalues.  */
5824           || TREE_CODE (TREE_TYPE (lhs)) == FUNCTION_TYPE
5825           || TREE_CODE (TREE_TYPE (lhs)) == METHOD_TYPE
5826           /* If it's an aggregate and any field is const, then it is
5827              effectively const.  */
5828           || (CLASS_TYPE_P (lhstype)
5829               && C_TYPE_FIELDS_READONLY (lhstype))))
5830     readonly_error (lhs, "assignment");
5831
5832   /* If storing into a structure or union member, it has probably been
5833      given type `int'.  Compute the type that would go with the actual
5834      amount of storage the member occupies.  */
5835
5836   if (TREE_CODE (lhs) == COMPONENT_REF
5837       && (TREE_CODE (lhstype) == INTEGER_TYPE
5838           || TREE_CODE (lhstype) == REAL_TYPE
5839           || TREE_CODE (lhstype) == ENUMERAL_TYPE))
5840     {
5841       lhstype = TREE_TYPE (get_unwidened (lhs, 0));
5842
5843       /* If storing in a field that is in actuality a short or narrower
5844          than one, we must store in the field in its actual type.  */
5845
5846       if (lhstype != TREE_TYPE (lhs))
5847         {
5848           /* Avoid warnings converting integral types back into enums for
5849              enum bit fields.  */
5850           if (TREE_CODE (lhstype) == INTEGER_TYPE
5851               && TREE_CODE (olhstype) == ENUMERAL_TYPE)
5852             {
5853               if (TREE_SIDE_EFFECTS (lhs))
5854                 lhs = stabilize_reference (lhs);
5855               olhs = lhs;
5856             }
5857           lhs = copy_node (lhs);
5858           TREE_TYPE (lhs) = lhstype;
5859         }
5860     }
5861
5862   /* Convert new value to destination type.  */
5863
5864   if (TREE_CODE (lhstype) == ARRAY_TYPE)
5865     {
5866       int from_array;
5867
5868       if (!same_or_base_type_p (TYPE_MAIN_VARIANT (lhstype),
5869                                 TYPE_MAIN_VARIANT (TREE_TYPE (rhs))))
5870         {
5871           error ("incompatible types in assignment of %qT to %qT",
5872                  TREE_TYPE (rhs), lhstype);
5873           return error_mark_node;
5874         }
5875
5876       /* Allow array assignment in compiler-generated code.  */
5877       if (! DECL_ARTIFICIAL (current_function_decl))
5878         {
5879           /* This routine is used for both initialization and assignment.
5880              Make sure the diagnostic message differentiates the context.  */
5881           if (modifycode == INIT_EXPR)
5882             error ("array used as initializer");
5883           else
5884             error ("invalid array assignment");
5885           return error_mark_node;
5886         }
5887
5888       from_array = TREE_CODE (TREE_TYPE (newrhs)) == ARRAY_TYPE
5889                    ? 1 + (modifycode != INIT_EXPR): 0;
5890       return build_vec_init (lhs, NULL_TREE, newrhs,
5891                              /*explicit_default_init_p=*/false,
5892                              from_array);
5893     }
5894
5895   if (modifycode == INIT_EXPR)
5896     newrhs = convert_for_initialization (lhs, lhstype, newrhs, LOOKUP_NORMAL,
5897                                          "initialization", NULL_TREE, 0);
5898   else
5899     {
5900       /* Avoid warnings on enum bit fields.  */
5901       if (TREE_CODE (olhstype) == ENUMERAL_TYPE
5902           && TREE_CODE (lhstype) == INTEGER_TYPE)
5903         {
5904           newrhs = convert_for_assignment (olhstype, newrhs, "assignment",
5905                                            NULL_TREE, 0);
5906           newrhs = convert_force (lhstype, newrhs, 0);
5907         }
5908       else
5909         newrhs = convert_for_assignment (lhstype, newrhs, "assignment",
5910                                          NULL_TREE, 0);
5911       if (TREE_CODE (newrhs) == CALL_EXPR
5912           && TYPE_NEEDS_CONSTRUCTING (lhstype))
5913         newrhs = build_cplus_new (lhstype, newrhs);
5914
5915       /* Can't initialize directly from a TARGET_EXPR, since that would
5916          cause the lhs to be constructed twice, and possibly result in
5917          accidental self-initialization.  So we force the TARGET_EXPR to be
5918          expanded without a target.  */
5919       if (TREE_CODE (newrhs) == TARGET_EXPR)
5920         newrhs = build2 (COMPOUND_EXPR, TREE_TYPE (newrhs), newrhs,
5921                          TREE_OPERAND (newrhs, 0));
5922     }
5923
5924   if (newrhs == error_mark_node)
5925     return error_mark_node;
5926
5927   if (c_dialect_objc () && flag_objc_gc)
5928     {
5929       result = objc_generate_write_barrier (lhs, modifycode, newrhs);
5930
5931       if (result)
5932         return result;
5933     }
5934
5935   result = build2 (modifycode == NOP_EXPR ? MODIFY_EXPR : INIT_EXPR,
5936                    lhstype, lhs, newrhs);
5937
5938   TREE_SIDE_EFFECTS (result) = 1;
5939   if (!plain_assign)
5940     TREE_NO_WARNING (result) = 1;
5941
5942   /* If we got the LHS in a different type for storing in,
5943      convert the result back to the nominal type of LHS
5944      so that the value we return always has the same type
5945      as the LHS argument.  */
5946
5947   if (olhstype == TREE_TYPE (result))
5948     return result;
5949   if (olhs)
5950     {
5951       result = build2 (COMPOUND_EXPR, olhstype, result, olhs);
5952       TREE_NO_WARNING (result) = 1;
5953       return result;
5954     }
5955   return convert_for_assignment (olhstype, result, "assignment",
5956                                  NULL_TREE, 0);
5957 }
5958
5959 tree
5960 build_x_modify_expr (tree lhs, enum tree_code modifycode, tree rhs)
5961 {
5962   if (processing_template_decl)
5963     return build_min_nt (MODOP_EXPR, lhs,
5964                          build_min_nt (modifycode, NULL_TREE, NULL_TREE), rhs);
5965
5966   if (modifycode != NOP_EXPR)
5967     {
5968       tree rval = build_new_op (MODIFY_EXPR, LOOKUP_NORMAL, lhs, rhs,
5969                                 make_node (modifycode),
5970                                 /*overloaded_p=*/NULL);
5971       if (rval)
5972         {
5973           TREE_NO_WARNING (rval) = 1;
5974           return rval;
5975         }
5976     }
5977   return build_modify_expr (lhs, modifycode, rhs);
5978 }
5979
5980 /* Helper function for get_delta_difference which assumes FROM is a base
5981    class of TO.  Returns a delta for the conversion of pointer-to-member
5982    of FROM to pointer-to-member of TO.  If the conversion is invalid,
5983    returns zero.  If FROM is not a base class of TO, returns NULL_TREE.
5984    If C_CAST_P is true, this conversion is taking place as part of a C-style
5985    cast.  */
5986
5987 static tree
5988 get_delta_difference_1 (tree from, tree to, bool c_cast_p)
5989 {
5990   tree binfo;
5991   base_kind kind;
5992
5993   binfo = lookup_base (to, from, c_cast_p ? ba_unique : ba_check, &kind);
5994   if (kind == bk_inaccessible || kind == bk_ambig)
5995     {
5996       error ("   in pointer to member function conversion");
5997       return size_zero_node;
5998     }
5999   else if (binfo)
6000     {
6001       if (kind != bk_via_virtual)
6002         return BINFO_OFFSET (binfo);
6003       else
6004         /* FROM is a virtual base class of TO.  Issue an error or warning
6005            depending on whether or not this is a reinterpret cast.  */
6006         {
6007           error ("pointer to member conversion via virtual base %qT",
6008                  BINFO_TYPE (binfo_from_vbase (binfo)));
6009
6010           return size_zero_node;
6011         }
6012       }
6013     else
6014       return NULL_TREE;
6015 }
6016
6017 /* Get difference in deltas for different pointer to member function
6018    types.  Returns an integer constant of type PTRDIFF_TYPE_NODE.  If
6019    the conversion is invalid, the constant is zero.  If
6020    ALLOW_INVERSE_P is true, then allow reverse conversions as well.
6021    If C_CAST_P is true this conversion is taking place as part of a
6022    C-style cast.
6023
6024    Note that the naming of FROM and TO is kind of backwards; the return
6025    value is what we add to a TO in order to get a FROM.  They are named
6026    this way because we call this function to find out how to convert from
6027    a pointer to member of FROM to a pointer to member of TO.  */
6028
6029 static tree
6030 get_delta_difference (tree from, tree to,
6031                       bool allow_inverse_p,
6032                       bool c_cast_p)
6033 {
6034   tree result;
6035
6036   if (same_type_ignoring_top_level_qualifiers_p (from, to))
6037     /* Pointer to member of incomplete class is permitted*/
6038     result = size_zero_node;
6039   else
6040     result = get_delta_difference_1 (from, to, c_cast_p);
6041
6042   if (!result)
6043   {
6044     if (!allow_inverse_p)
6045       {
6046         error_not_base_type (from, to);
6047         error ("   in pointer to member conversion");
6048         result = size_zero_node;
6049       }
6050     else
6051       {
6052         result = get_delta_difference_1 (to, from, c_cast_p);
6053
6054         if (result)
6055           result = size_diffop (size_zero_node, result);
6056         else
6057           {
6058             error_not_base_type (from, to);
6059             error ("   in pointer to member conversion");
6060             result = size_zero_node;
6061           }
6062       }
6063   }
6064
6065   return fold_if_not_in_template (convert_to_integer (ptrdiff_type_node,
6066                                                       result));
6067 }
6068
6069 /* Return a constructor for the pointer-to-member-function TYPE using
6070    the other components as specified.  */
6071
6072 tree
6073 build_ptrmemfunc1 (tree type, tree delta, tree pfn)
6074 {
6075   tree u = NULL_TREE;
6076   tree delta_field;
6077   tree pfn_field;
6078   VEC(constructor_elt, gc) *v;
6079
6080   /* Pull the FIELD_DECLs out of the type.  */
6081   pfn_field = TYPE_FIELDS (type);
6082   delta_field = TREE_CHAIN (pfn_field);
6083
6084   /* Make sure DELTA has the type we want.  */
6085   delta = convert_and_check (delta_type_node, delta);
6086
6087   /* Convert to the correct target type if necessary.  */
6088   pfn = fold_convert (TREE_TYPE (pfn_field), pfn);
6089
6090   /* Finish creating the initializer.  */
6091   v = VEC_alloc(constructor_elt, gc, 2);
6092   CONSTRUCTOR_APPEND_ELT(v, pfn_field, pfn);
6093   CONSTRUCTOR_APPEND_ELT(v, delta_field, delta);
6094   u = build_constructor (type, v);
6095   TREE_CONSTANT (u) = TREE_CONSTANT (pfn) & TREE_CONSTANT (delta);
6096   TREE_INVARIANT (u) = TREE_INVARIANT (pfn) & TREE_INVARIANT (delta);
6097   TREE_STATIC (u) = (TREE_CONSTANT (u)
6098                      && (initializer_constant_valid_p (pfn, TREE_TYPE (pfn))
6099                          != NULL_TREE)
6100                      && (initializer_constant_valid_p (delta, TREE_TYPE (delta))
6101                          != NULL_TREE));
6102   return u;
6103 }
6104
6105 /* Build a constructor for a pointer to member function.  It can be
6106    used to initialize global variables, local variable, or used
6107    as a value in expressions.  TYPE is the POINTER to METHOD_TYPE we
6108    want to be.
6109
6110    If FORCE is nonzero, then force this conversion, even if
6111    we would rather not do it.  Usually set when using an explicit
6112    cast.  A C-style cast is being processed iff C_CAST_P is true.
6113
6114    Return error_mark_node, if something goes wrong.  */
6115
6116 tree
6117 build_ptrmemfunc (tree type, tree pfn, int force, bool c_cast_p)
6118 {
6119   tree fn;
6120   tree pfn_type;
6121   tree to_type;
6122
6123   if (error_operand_p (pfn))
6124     return error_mark_node;
6125
6126   pfn_type = TREE_TYPE (pfn);
6127   to_type = build_ptrmemfunc_type (type);
6128
6129   /* Handle multiple conversions of pointer to member functions.  */
6130   if (TYPE_PTRMEMFUNC_P (pfn_type))
6131     {
6132       tree delta = NULL_TREE;
6133       tree npfn = NULL_TREE;
6134       tree n;
6135
6136       if (!force
6137           && !can_convert_arg (to_type, TREE_TYPE (pfn), pfn, LOOKUP_NORMAL))
6138         error ("invalid conversion to type %qT from type %qT",
6139                to_type, pfn_type);
6140
6141       n = get_delta_difference (TYPE_PTRMEMFUNC_OBJECT_TYPE (pfn_type),
6142                                 TYPE_PTRMEMFUNC_OBJECT_TYPE (to_type),
6143                                 force,
6144                                 c_cast_p);
6145
6146       /* We don't have to do any conversion to convert a
6147          pointer-to-member to its own type.  But, we don't want to
6148          just return a PTRMEM_CST if there's an explicit cast; that
6149          cast should make the expression an invalid template argument.  */
6150       if (TREE_CODE (pfn) != PTRMEM_CST)
6151         {
6152           if (same_type_p (to_type, pfn_type))
6153             return pfn;
6154           else if (integer_zerop (n))
6155             return build_reinterpret_cast (to_type, pfn);
6156         }
6157
6158       if (TREE_SIDE_EFFECTS (pfn))
6159         pfn = save_expr (pfn);
6160
6161       /* Obtain the function pointer and the current DELTA.  */
6162       if (TREE_CODE (pfn) == PTRMEM_CST)
6163         expand_ptrmemfunc_cst (pfn, &delta, &npfn);
6164       else
6165         {
6166           npfn = build_ptrmemfunc_access_expr (pfn, pfn_identifier);
6167           delta = build_ptrmemfunc_access_expr (pfn, delta_identifier);
6168         }
6169
6170       /* Just adjust the DELTA field.  */
6171       gcc_assert  (same_type_ignoring_top_level_qualifiers_p
6172                    (TREE_TYPE (delta), ptrdiff_type_node));
6173       if (TARGET_PTRMEMFUNC_VBIT_LOCATION == ptrmemfunc_vbit_in_delta)
6174         n = cp_build_binary_op (LSHIFT_EXPR, n, integer_one_node);
6175       delta = cp_build_binary_op (PLUS_EXPR, delta, n);
6176       return build_ptrmemfunc1 (to_type, delta, npfn);
6177     }
6178
6179   /* Handle null pointer to member function conversions.  */
6180   if (integer_zerop (pfn))
6181     {
6182       pfn = build_c_cast (type, integer_zero_node);
6183       return build_ptrmemfunc1 (to_type,
6184                                 integer_zero_node,
6185                                 pfn);
6186     }
6187
6188   if (type_unknown_p (pfn))
6189     return instantiate_type (type, pfn, tf_warning_or_error);
6190
6191   fn = TREE_OPERAND (pfn, 0);
6192   gcc_assert (TREE_CODE (fn) == FUNCTION_DECL
6193               /* In a template, we will have preserved the
6194                  OFFSET_REF.  */
6195               || (processing_template_decl && TREE_CODE (fn) == OFFSET_REF));
6196   return make_ptrmem_cst (to_type, fn);
6197 }
6198
6199 /* Return the DELTA, IDX, PFN, and DELTA2 values for the PTRMEM_CST
6200    given by CST.
6201
6202    ??? There is no consistency as to the types returned for the above
6203    values.  Some code acts as if it were a sizetype and some as if it were
6204    integer_type_node.  */
6205
6206 void
6207 expand_ptrmemfunc_cst (tree cst, tree *delta, tree *pfn)
6208 {
6209   tree type = TREE_TYPE (cst);
6210   tree fn = PTRMEM_CST_MEMBER (cst);
6211   tree ptr_class, fn_class;
6212
6213   gcc_assert (TREE_CODE (fn) == FUNCTION_DECL);
6214
6215   /* The class that the function belongs to.  */
6216   fn_class = DECL_CONTEXT (fn);
6217
6218   /* The class that we're creating a pointer to member of.  */
6219   ptr_class = TYPE_PTRMEMFUNC_OBJECT_TYPE (type);
6220
6221   /* First, calculate the adjustment to the function's class.  */
6222   *delta = get_delta_difference (fn_class, ptr_class, /*force=*/0,
6223                                  /*c_cast_p=*/0);
6224
6225   if (!DECL_VIRTUAL_P (fn))
6226     *pfn = convert (TYPE_PTRMEMFUNC_FN_TYPE (type), build_addr_func (fn));
6227   else
6228     {
6229       /* If we're dealing with a virtual function, we have to adjust 'this'
6230          again, to point to the base which provides the vtable entry for
6231          fn; the call will do the opposite adjustment.  */
6232       tree orig_class = DECL_CONTEXT (fn);
6233       tree binfo = binfo_or_else (orig_class, fn_class);
6234       *delta = build2 (PLUS_EXPR, TREE_TYPE (*delta),
6235                        *delta, BINFO_OFFSET (binfo));
6236       *delta = fold_if_not_in_template (*delta);
6237
6238       /* We set PFN to the vtable offset at which the function can be
6239          found, plus one (unless ptrmemfunc_vbit_in_delta, in which
6240          case delta is shifted left, and then incremented).  */
6241       *pfn = DECL_VINDEX (fn);
6242       *pfn = build2 (MULT_EXPR, integer_type_node, *pfn,
6243                      TYPE_SIZE_UNIT (vtable_entry_type));
6244       *pfn = fold_if_not_in_template (*pfn);
6245
6246       switch (TARGET_PTRMEMFUNC_VBIT_LOCATION)
6247         {
6248         case ptrmemfunc_vbit_in_pfn:
6249           *pfn = build2 (PLUS_EXPR, integer_type_node, *pfn,
6250                          integer_one_node);
6251           *pfn = fold_if_not_in_template (*pfn);
6252           break;
6253
6254         case ptrmemfunc_vbit_in_delta:
6255           *delta = build2 (LSHIFT_EXPR, TREE_TYPE (*delta),
6256                            *delta, integer_one_node);
6257           *delta = fold_if_not_in_template (*delta);
6258           *delta = build2 (PLUS_EXPR, TREE_TYPE (*delta),
6259                            *delta, integer_one_node);
6260           *delta = fold_if_not_in_template (*delta);
6261           break;
6262
6263         default:
6264           gcc_unreachable ();
6265         }
6266
6267       *pfn = build_nop (TYPE_PTRMEMFUNC_FN_TYPE (type), *pfn);
6268       *pfn = fold_if_not_in_template (*pfn);
6269     }
6270 }
6271
6272 /* Return an expression for PFN from the pointer-to-member function
6273    given by T.  */
6274
6275 static tree
6276 pfn_from_ptrmemfunc (tree t)
6277 {
6278   if (TREE_CODE (t) == PTRMEM_CST)
6279     {
6280       tree delta;
6281       tree pfn;
6282
6283       expand_ptrmemfunc_cst (t, &delta, &pfn);
6284       if (pfn)
6285         return pfn;
6286     }
6287
6288   return build_ptrmemfunc_access_expr (t, pfn_identifier);
6289 }
6290
6291 /* Convert value RHS to type TYPE as preparation for an assignment to
6292    an lvalue of type TYPE.  ERRTYPE is a string to use in error
6293    messages: "assignment", "return", etc.  If FNDECL is non-NULL, we
6294    are doing the conversion in order to pass the PARMNUMth argument of
6295    FNDECL.  */
6296
6297 static tree
6298 convert_for_assignment (tree type, tree rhs,
6299                         const char *errtype, tree fndecl, int parmnum)
6300 {
6301   tree rhstype;
6302   enum tree_code coder;
6303
6304   /* Strip NON_LVALUE_EXPRs since we aren't using as an lvalue.  */
6305   if (TREE_CODE (rhs) == NON_LVALUE_EXPR)
6306     rhs = TREE_OPERAND (rhs, 0);
6307
6308   rhstype = TREE_TYPE (rhs);
6309   coder = TREE_CODE (rhstype);
6310
6311   if (TREE_CODE (type) == VECTOR_TYPE && coder == VECTOR_TYPE
6312       && vector_types_convertible_p (type, rhstype, true))
6313     return convert (type, rhs);
6314
6315   if (rhs == error_mark_node || rhstype == error_mark_node)
6316     return error_mark_node;
6317   if (TREE_CODE (rhs) == TREE_LIST && TREE_VALUE (rhs) == error_mark_node)
6318     return error_mark_node;
6319
6320   /* The RHS of an assignment cannot have void type.  */
6321   if (coder == VOID_TYPE)
6322     {
6323       error ("void value not ignored as it ought to be");
6324       return error_mark_node;
6325     }
6326
6327   /* Simplify the RHS if possible.  */
6328   if (TREE_CODE (rhs) == CONST_DECL)
6329     rhs = DECL_INITIAL (rhs);
6330
6331   if (c_dialect_objc ())
6332     {
6333       int parmno;
6334       tree rname = fndecl;
6335
6336       if (!strcmp (errtype, "assignment"))
6337         parmno = -1;
6338       else if (!strcmp (errtype, "initialization"))
6339         parmno = -2;
6340       else
6341         {
6342           tree selector = objc_message_selector ();
6343
6344           parmno = parmnum;
6345
6346           if (selector && parmno > 1)
6347             {
6348               rname = selector;
6349               parmno -= 1;
6350             }
6351         }
6352
6353       if (objc_compare_types (type, rhstype, parmno, rname))
6354         return convert (type, rhs);
6355     }
6356
6357   /* [expr.ass]
6358
6359      The expression is implicitly converted (clause _conv_) to the
6360      cv-unqualified type of the left operand.
6361
6362      We allow bad conversions here because by the time we get to this point
6363      we are committed to doing the conversion.  If we end up doing a bad
6364      conversion, convert_like will complain.  */
6365   if (!can_convert_arg_bad (type, rhstype, rhs))
6366     {
6367       /* When -Wno-pmf-conversions is use, we just silently allow
6368          conversions from pointers-to-members to plain pointers.  If
6369          the conversion doesn't work, cp_convert will complain.  */
6370       if (!warn_pmf2ptr
6371           && TYPE_PTR_P (type)
6372           && TYPE_PTRMEMFUNC_P (rhstype))
6373         rhs = cp_convert (strip_top_quals (type), rhs);
6374       else
6375         {
6376           /* If the right-hand side has unknown type, then it is an
6377              overloaded function.  Call instantiate_type to get error
6378              messages.  */
6379           if (rhstype == unknown_type_node)
6380             instantiate_type (type, rhs, tf_warning_or_error);
6381           else if (fndecl)
6382             error ("cannot convert %qT to %qT for argument %qP to %qD",
6383                    rhstype, type, parmnum, fndecl);
6384           else
6385             error ("cannot convert %qT to %qT in %s", rhstype, type, errtype);
6386           return error_mark_node;
6387         }
6388     }
6389   if (warn_missing_format_attribute)
6390     {
6391       const enum tree_code codel = TREE_CODE (type);
6392       if ((codel == POINTER_TYPE || codel == REFERENCE_TYPE)
6393           && coder == codel
6394           && check_missing_format_attribute (type, rhstype))
6395         warning (OPT_Wmissing_format_attribute,
6396                  "%s might be a candidate for a format attribute",
6397                  errtype);
6398     }
6399
6400   /* If -Wparentheses, warn about a = b = c when a has type bool and b
6401      does not.  */
6402   if (warn_parentheses
6403       && type == boolean_type_node
6404       && TREE_CODE (rhs) == MODIFY_EXPR
6405       && !TREE_NO_WARNING (rhs)
6406       && TREE_TYPE (rhs) != boolean_type_node)
6407     {
6408       warning (OPT_Wparentheses,
6409                "suggest parentheses around assignment used as truth value");
6410       TREE_NO_WARNING (rhs) = 1;
6411     }
6412
6413   return perform_implicit_conversion (strip_top_quals (type), rhs);
6414 }
6415
6416 /* Convert RHS to be of type TYPE.
6417    If EXP is nonzero, it is the target of the initialization.
6418    ERRTYPE is a string to use in error messages.
6419
6420    Two major differences between the behavior of
6421    `convert_for_assignment' and `convert_for_initialization'
6422    are that references are bashed in the former, while
6423    copied in the latter, and aggregates are assigned in
6424    the former (operator=) while initialized in the
6425    latter (X(X&)).
6426
6427    If using constructor make sure no conversion operator exists, if one does
6428    exist, an ambiguity exists.
6429
6430    If flags doesn't include LOOKUP_COMPLAIN, don't complain about anything.  */
6431
6432 tree
6433 convert_for_initialization (tree exp, tree type, tree rhs, int flags,
6434                             const char *errtype, tree fndecl, int parmnum)
6435 {
6436   enum tree_code codel = TREE_CODE (type);
6437   tree rhstype;
6438   enum tree_code coder;
6439
6440   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
6441      Strip such NOP_EXPRs, since RHS is used in non-lvalue context.  */
6442   if (TREE_CODE (rhs) == NOP_EXPR
6443       && TREE_TYPE (rhs) == TREE_TYPE (TREE_OPERAND (rhs, 0))
6444       && codel != REFERENCE_TYPE)
6445     rhs = TREE_OPERAND (rhs, 0);
6446
6447   if (type == error_mark_node
6448       || rhs == error_mark_node
6449       || (TREE_CODE (rhs) == TREE_LIST && TREE_VALUE (rhs) == error_mark_node))
6450     return error_mark_node;
6451
6452   if ((TREE_CODE (TREE_TYPE (rhs)) == ARRAY_TYPE
6453        && TREE_CODE (type) != ARRAY_TYPE
6454        && (TREE_CODE (type) != REFERENCE_TYPE
6455            || TREE_CODE (TREE_TYPE (type)) != ARRAY_TYPE))
6456       || (TREE_CODE (TREE_TYPE (rhs)) == FUNCTION_TYPE
6457           && (TREE_CODE (type) != REFERENCE_TYPE
6458               || TREE_CODE (TREE_TYPE (type)) != FUNCTION_TYPE))
6459       || TREE_CODE (TREE_TYPE (rhs)) == METHOD_TYPE)
6460     rhs = decay_conversion (rhs);
6461
6462   rhstype = TREE_TYPE (rhs);
6463   coder = TREE_CODE (rhstype);
6464
6465   if (coder == ERROR_MARK)
6466     return error_mark_node;
6467
6468   /* We accept references to incomplete types, so we can
6469      return here before checking if RHS is of complete type.  */
6470
6471   if (codel == REFERENCE_TYPE)
6472     {
6473       /* This should eventually happen in convert_arguments.  */
6474       int savew = 0, savee = 0;
6475
6476       if (fndecl)
6477         savew = warningcount, savee = errorcount;
6478       rhs = initialize_reference (type, rhs, /*decl=*/NULL_TREE,
6479                                   /*cleanup=*/NULL);
6480       if (fndecl)
6481         {
6482           if (warningcount > savew)
6483             warning (0, "in passing argument %P of %q+D", parmnum, fndecl);
6484           else if (errorcount > savee)
6485             error ("in passing argument %P of %q+D", parmnum, fndecl);
6486         }
6487       return rhs;
6488     }
6489
6490   if (exp != 0)
6491     exp = require_complete_type (exp);
6492   if (exp == error_mark_node)
6493     return error_mark_node;
6494
6495   rhstype = non_reference (rhstype);
6496
6497   type = complete_type (type);
6498
6499   if (IS_AGGR_TYPE (type))
6500     return ocp_convert (type, rhs, CONV_IMPLICIT|CONV_FORCE_TEMP, flags);
6501
6502   return convert_for_assignment (type, rhs, errtype, fndecl, parmnum);
6503 }
6504 \f
6505 /* If RETVAL is the address of, or a reference to, a local variable or
6506    temporary give an appropriate warning.  */
6507
6508 static void
6509 maybe_warn_about_returning_address_of_local (tree retval)
6510 {
6511   tree valtype = TREE_TYPE (DECL_RESULT (current_function_decl));
6512   tree whats_returned = retval;
6513
6514   for (;;)
6515     {
6516       if (TREE_CODE (whats_returned) == COMPOUND_EXPR)
6517         whats_returned = TREE_OPERAND (whats_returned, 1);
6518       else if (TREE_CODE (whats_returned) == CONVERT_EXPR
6519                || TREE_CODE (whats_returned) == NON_LVALUE_EXPR
6520                || TREE_CODE (whats_returned) == NOP_EXPR)
6521         whats_returned = TREE_OPERAND (whats_returned, 0);
6522       else
6523         break;
6524     }
6525
6526   if (TREE_CODE (whats_returned) != ADDR_EXPR)
6527     return;
6528   whats_returned = TREE_OPERAND (whats_returned, 0);
6529
6530   if (TREE_CODE (valtype) == REFERENCE_TYPE)
6531     {
6532       if (TREE_CODE (whats_returned) == AGGR_INIT_EXPR
6533           || TREE_CODE (whats_returned) == TARGET_EXPR)
6534         {
6535           warning (0, "returning reference to temporary");
6536           return;
6537         }
6538       if (TREE_CODE (whats_returned) == VAR_DECL
6539           && DECL_NAME (whats_returned)
6540           && TEMP_NAME_P (DECL_NAME (whats_returned)))
6541         {
6542           warning (0, "reference to non-lvalue returned");
6543           return;
6544         }
6545     }
6546
6547   while (TREE_CODE (whats_returned) == COMPONENT_REF
6548          || TREE_CODE (whats_returned) == ARRAY_REF)
6549     whats_returned = TREE_OPERAND (whats_returned, 0);
6550
6551   if (DECL_P (whats_returned)
6552       && DECL_NAME (whats_returned)
6553       && DECL_FUNCTION_SCOPE_P (whats_returned)
6554       && !(TREE_STATIC (whats_returned)
6555            || TREE_PUBLIC (whats_returned)))
6556     {
6557       if (TREE_CODE (valtype) == REFERENCE_TYPE)
6558         warning (0, "reference to local variable %q+D returned",
6559                  whats_returned);
6560       else
6561         warning (0, "address of local variable %q+D returned",
6562                  whats_returned);
6563       return;
6564     }
6565 }
6566
6567 /* Check that returning RETVAL from the current function is valid.
6568    Return an expression explicitly showing all conversions required to
6569    change RETVAL into the function return type, and to assign it to
6570    the DECL_RESULT for the function.  Set *NO_WARNING to true if
6571    code reaches end of non-void function warning shouldn't be issued
6572    on this RETURN_EXPR.  */
6573
6574 tree
6575 check_return_expr (tree retval, bool *no_warning)
6576 {
6577   tree result;
6578   /* The type actually returned by the function, after any
6579      promotions.  */
6580   tree valtype;
6581   int fn_returns_value_p;
6582   bool named_return_value_okay_p;
6583
6584   *no_warning = false;
6585
6586   /* A `volatile' function is one that isn't supposed to return, ever.
6587      (This is a G++ extension, used to get better code for functions
6588      that call the `volatile' function.)  */
6589   if (TREE_THIS_VOLATILE (current_function_decl))
6590     warning (0, "function declared %<noreturn%> has a %<return%> statement");
6591
6592   /* Check for various simple errors.  */
6593   if (DECL_DESTRUCTOR_P (current_function_decl))
6594     {
6595       if (retval)
6596         error ("returning a value from a destructor");
6597       return NULL_TREE;
6598     }
6599   else if (DECL_CONSTRUCTOR_P (current_function_decl))
6600     {
6601       if (in_function_try_handler)
6602         /* If a return statement appears in a handler of the
6603            function-try-block of a constructor, the program is ill-formed.  */
6604         error ("cannot return from a handler of a function-try-block of a constructor");
6605       else if (retval)
6606         /* You can't return a value from a constructor.  */
6607         error ("returning a value from a constructor");
6608       return NULL_TREE;
6609     }
6610
6611   if (processing_template_decl)
6612     {
6613       current_function_returns_value = 1;
6614       check_for_bare_parameter_packs (retval);
6615       return retval;
6616     }
6617
6618   /* When no explicit return-value is given in a function with a named
6619      return value, the named return value is used.  */
6620   result = DECL_RESULT (current_function_decl);
6621   valtype = TREE_TYPE (result);
6622   gcc_assert (valtype != NULL_TREE);
6623   fn_returns_value_p = !VOID_TYPE_P (valtype);
6624   if (!retval && DECL_NAME (result) && fn_returns_value_p)
6625     retval = result;
6626
6627   /* Check for a return statement with no return value in a function
6628      that's supposed to return a value.  */
6629   if (!retval && fn_returns_value_p)
6630     {
6631       pedwarn ("return-statement with no value, in function returning %qT",
6632                valtype);
6633       /* Clear this, so finish_function won't say that we reach the
6634          end of a non-void function (which we don't, we gave a
6635          return!).  */
6636       current_function_returns_null = 0;
6637       /* And signal caller that TREE_NO_WARNING should be set on the
6638          RETURN_EXPR to avoid control reaches end of non-void function
6639          warnings in tree-cfg.c.  */
6640       *no_warning = true;
6641     }
6642   /* Check for a return statement with a value in a function that
6643      isn't supposed to return a value.  */
6644   else if (retval && !fn_returns_value_p)
6645     {
6646       if (VOID_TYPE_P (TREE_TYPE (retval)))
6647         /* You can return a `void' value from a function of `void'
6648            type.  In that case, we have to evaluate the expression for
6649            its side-effects.  */
6650           finish_expr_stmt (retval);
6651       else
6652         pedwarn ("return-statement with a value, in function "
6653                  "returning 'void'");
6654
6655       current_function_returns_null = 1;
6656
6657       /* There's really no value to return, after all.  */
6658       return NULL_TREE;
6659     }
6660   else if (!retval)
6661     /* Remember that this function can sometimes return without a
6662        value.  */
6663     current_function_returns_null = 1;
6664   else
6665     /* Remember that this function did return a value.  */
6666     current_function_returns_value = 1;
6667
6668   /* Check for erroneous operands -- but after giving ourselves a
6669      chance to provide an error about returning a value from a void
6670      function.  */
6671   if (error_operand_p (retval))
6672     {
6673       current_function_return_value = error_mark_node;
6674       return error_mark_node;
6675     }
6676
6677   /* Only operator new(...) throw(), can return NULL [expr.new/13].  */
6678   if ((DECL_OVERLOADED_OPERATOR_P (current_function_decl) == NEW_EXPR
6679        || DECL_OVERLOADED_OPERATOR_P (current_function_decl) == VEC_NEW_EXPR)
6680       && !TYPE_NOTHROW_P (TREE_TYPE (current_function_decl))
6681       && ! flag_check_new
6682       && retval && null_ptr_cst_p (retval))
6683     warning (0, "%<operator new%> must not return NULL unless it is "
6684              "declared %<throw()%> (or -fcheck-new is in effect)");
6685
6686   /* Effective C++ rule 15.  See also start_function.  */
6687   if (warn_ecpp
6688       && DECL_NAME (current_function_decl) == ansi_assopname(NOP_EXPR))
6689     {
6690       bool warn = true;
6691
6692       /* The function return type must be a reference to the current
6693         class.  */
6694       if (TREE_CODE (valtype) == REFERENCE_TYPE
6695           && same_type_ignoring_top_level_qualifiers_p
6696               (TREE_TYPE (valtype), TREE_TYPE (current_class_ref)))
6697         {
6698           /* Returning '*this' is obviously OK.  */
6699           if (retval == current_class_ref)
6700             warn = false;
6701           /* If we are calling a function whose return type is the same of
6702              the current class reference, it is ok.  */
6703           else if (TREE_CODE (retval) == INDIRECT_REF
6704                    && TREE_CODE (TREE_OPERAND (retval, 0)) == CALL_EXPR)
6705             warn = false;
6706         }
6707
6708       if (warn)
6709         warning (OPT_Weffc__, "%<operator=%> should return a reference to %<*this%>");
6710     }
6711
6712   /* The fabled Named Return Value optimization, as per [class.copy]/15:
6713
6714      [...]      For  a function with a class return type, if the expression
6715      in the return statement is the name of a local  object,  and  the  cv-
6716      unqualified  type  of  the  local  object  is the same as the function
6717      return type, an implementation is permitted to omit creating the  tem-
6718      porary  object  to  hold  the function return value [...]
6719
6720      So, if this is a value-returning function that always returns the same
6721      local variable, remember it.
6722
6723      It might be nice to be more flexible, and choose the first suitable
6724      variable even if the function sometimes returns something else, but
6725      then we run the risk of clobbering the variable we chose if the other
6726      returned expression uses the chosen variable somehow.  And people expect
6727      this restriction, anyway.  (jason 2000-11-19)
6728
6729      See finish_function and finalize_nrv for the rest of this optimization.  */
6730
6731   named_return_value_okay_p =
6732     (retval != NULL_TREE
6733      /* Must be a local, automatic variable.  */
6734      && TREE_CODE (retval) == VAR_DECL
6735      && DECL_CONTEXT (retval) == current_function_decl
6736      && ! TREE_STATIC (retval)
6737      && ! DECL_ANON_UNION_VAR_P (retval)
6738      && (DECL_ALIGN (retval)
6739          >= DECL_ALIGN (DECL_RESULT (current_function_decl)))
6740      /* The cv-unqualified type of the returned value must be the
6741         same as the cv-unqualified return type of the
6742         function.  */
6743      && same_type_p ((TYPE_MAIN_VARIANT (TREE_TYPE (retval))),
6744                      (TYPE_MAIN_VARIANT
6745                       (TREE_TYPE (TREE_TYPE (current_function_decl))))));
6746
6747   if (fn_returns_value_p && flag_elide_constructors)
6748     {
6749       if (named_return_value_okay_p
6750           && (current_function_return_value == NULL_TREE
6751               || current_function_return_value == retval))
6752         current_function_return_value = retval;
6753       else
6754         current_function_return_value = error_mark_node;
6755     }
6756
6757   /* We don't need to do any conversions when there's nothing being
6758      returned.  */
6759   if (!retval)
6760     return NULL_TREE;
6761
6762   /* Do any required conversions.  */
6763   if (retval == result || DECL_CONSTRUCTOR_P (current_function_decl))
6764     /* No conversions are required.  */
6765     ;
6766   else
6767     {
6768       /* The type the function is declared to return.  */
6769       tree functype = TREE_TYPE (TREE_TYPE (current_function_decl));
6770       int flags = LOOKUP_NORMAL | LOOKUP_ONLYCONVERTING;
6771
6772       /* The functype's return type will have been set to void, if it
6773          was an incomplete type.  Just treat this as 'return;' */
6774       if (VOID_TYPE_P (functype))
6775         return error_mark_node;
6776
6777       /* Under C++0x [12.8/16 class.copy], a returned lvalue is sometimes
6778          treated as an rvalue for the purposes of overload resolution to
6779          favor move constructors over copy constructors.  */
6780       if ((cxx_dialect != cxx98)
6781           && named_return_value_okay_p
6782           /* The variable must not have the `volatile' qualifier.  */
6783           && !(cp_type_quals (TREE_TYPE (retval)) & TYPE_QUAL_VOLATILE)
6784           /* The return type must be a class type.  */
6785           && CLASS_TYPE_P (TREE_TYPE (TREE_TYPE (current_function_decl))))
6786         flags = flags | LOOKUP_PREFER_RVALUE;
6787
6788       /* First convert the value to the function's return type, then
6789          to the type of return value's location to handle the
6790          case that functype is smaller than the valtype.  */
6791       retval = convert_for_initialization
6792         (NULL_TREE, functype, retval, flags, "return", NULL_TREE, 0);
6793       retval = convert (valtype, retval);
6794
6795       /* If the conversion failed, treat this just like `return;'.  */
6796       if (retval == error_mark_node)
6797         return retval;
6798       /* We can't initialize a register from a AGGR_INIT_EXPR.  */
6799       else if (! current_function_returns_struct
6800                && TREE_CODE (retval) == TARGET_EXPR
6801                && TREE_CODE (TREE_OPERAND (retval, 1)) == AGGR_INIT_EXPR)
6802         retval = build2 (COMPOUND_EXPR, TREE_TYPE (retval), retval,
6803                          TREE_OPERAND (retval, 0));
6804       else
6805         maybe_warn_about_returning_address_of_local (retval);
6806     }
6807
6808   /* Actually copy the value returned into the appropriate location.  */
6809   if (retval && retval != result)
6810     retval = build2 (INIT_EXPR, TREE_TYPE (result), result, retval);
6811
6812   return retval;
6813 }
6814
6815 \f
6816 /* Returns nonzero if the pointer-type FROM can be converted to the
6817    pointer-type TO via a qualification conversion.  If CONSTP is -1,
6818    then we return nonzero if the pointers are similar, and the
6819    cv-qualification signature of FROM is a proper subset of that of TO.
6820
6821    If CONSTP is positive, then all outer pointers have been
6822    const-qualified.  */
6823
6824 static int
6825 comp_ptr_ttypes_real (tree to, tree from, int constp)
6826 {
6827   bool to_more_cv_qualified = false;
6828
6829   for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
6830     {
6831       if (TREE_CODE (to) != TREE_CODE (from))
6832         return 0;
6833
6834       if (TREE_CODE (from) == OFFSET_TYPE
6835           && !same_type_p (TYPE_OFFSET_BASETYPE (from),
6836                            TYPE_OFFSET_BASETYPE (to)))
6837         return 0;
6838
6839       /* Const and volatile mean something different for function types,
6840          so the usual checks are not appropriate.  */
6841       if (TREE_CODE (to) != FUNCTION_TYPE && TREE_CODE (to) != METHOD_TYPE)
6842         {
6843           /* In Objective-C++, some types may have been 'volatilized' by
6844              the compiler for EH; when comparing them here, the volatile
6845              qualification must be ignored.  */
6846           bool objc_quals_match = objc_type_quals_match (to, from);
6847
6848           if (!at_least_as_qualified_p (to, from) && !objc_quals_match)
6849             return 0;
6850
6851           if (!at_least_as_qualified_p (from, to) && !objc_quals_match)
6852             {
6853               if (constp == 0)
6854                 return 0;
6855               to_more_cv_qualified = true;
6856             }
6857
6858           if (constp > 0)
6859             constp &= TYPE_READONLY (to);
6860         }
6861
6862       if (TREE_CODE (to) != POINTER_TYPE && !TYPE_PTRMEM_P (to))
6863         return ((constp >= 0 || to_more_cv_qualified)
6864                 && same_type_ignoring_top_level_qualifiers_p (to, from));
6865     }
6866 }
6867
6868 /* When comparing, say, char ** to char const **, this function takes
6869    the 'char *' and 'char const *'.  Do not pass non-pointer/reference
6870    types to this function.  */
6871
6872 int
6873 comp_ptr_ttypes (tree to, tree from)
6874 {
6875   return comp_ptr_ttypes_real (to, from, 1);
6876 }
6877
6878 /* Returns 1 if to and from are (possibly multi-level) pointers to the same
6879    type or inheritance-related types, regardless of cv-quals.  */
6880
6881 int
6882 ptr_reasonably_similar (const_tree to, const_tree from)
6883 {
6884   for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
6885     {
6886       /* Any target type is similar enough to void.  */
6887       if (TREE_CODE (to) == VOID_TYPE
6888           || TREE_CODE (from) == VOID_TYPE)
6889         return 1;
6890
6891       if (TREE_CODE (to) != TREE_CODE (from))
6892         return 0;
6893
6894       if (TREE_CODE (from) == OFFSET_TYPE
6895           && comptypes (TYPE_OFFSET_BASETYPE (to),
6896                         TYPE_OFFSET_BASETYPE (from),
6897                         COMPARE_BASE | COMPARE_DERIVED))
6898         continue;
6899
6900       if (TREE_CODE (to) == VECTOR_TYPE
6901           && vector_types_convertible_p (to, from, false))
6902         return 1;
6903
6904       if (TREE_CODE (to) == INTEGER_TYPE
6905           && TYPE_PRECISION (to) == TYPE_PRECISION (from))
6906         return 1;
6907
6908       if (TREE_CODE (to) == FUNCTION_TYPE)
6909         return 1;
6910
6911       if (TREE_CODE (to) != POINTER_TYPE)
6912         return comptypes
6913           (TYPE_MAIN_VARIANT (to), TYPE_MAIN_VARIANT (from),
6914            COMPARE_BASE | COMPARE_DERIVED);
6915     }
6916 }
6917
6918 /* Return true if TO and FROM (both of which are POINTER_TYPEs or
6919    pointer-to-member types) are the same, ignoring cv-qualification at
6920    all levels.  */
6921
6922 bool
6923 comp_ptr_ttypes_const (tree to, tree from)
6924 {
6925   for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
6926     {
6927       if (TREE_CODE (to) != TREE_CODE (from))
6928         return false;
6929
6930       if (TREE_CODE (from) == OFFSET_TYPE
6931           && same_type_p (TYPE_OFFSET_BASETYPE (from),
6932                           TYPE_OFFSET_BASETYPE (to)))
6933           continue;
6934
6935       if (TREE_CODE (to) != POINTER_TYPE)
6936         return same_type_ignoring_top_level_qualifiers_p (to, from);
6937     }
6938 }
6939
6940 /* Returns the type qualifiers for this type, including the qualifiers on the
6941    elements for an array type.  */
6942
6943 int
6944 cp_type_quals (const_tree type)
6945 {
6946   type = const_strip_array_types (type);
6947   if (type == error_mark_node)
6948     return TYPE_UNQUALIFIED;
6949   return TYPE_QUALS (type);
6950 }
6951
6952 /* Returns nonzero if the TYPE is const from a C++ perspective: look inside
6953    arrays.  */
6954
6955 bool
6956 cp_type_readonly (const_tree type)
6957 {
6958   type = const_strip_array_types (type);
6959   return TYPE_READONLY (type);
6960 }
6961
6962 /* Returns nonzero if the TYPE contains a mutable member.  */
6963
6964 bool
6965 cp_has_mutable_p (const_tree type)
6966 {
6967   type = const_strip_array_types (type);
6968
6969   return CLASS_TYPE_P (type) && CLASSTYPE_HAS_MUTABLE (type);
6970 }
6971
6972 /* Apply the TYPE_QUALS to the new DECL.  */
6973 void
6974 cp_apply_type_quals_to_decl (int type_quals, tree decl)
6975 {
6976   tree type = TREE_TYPE (decl);
6977
6978   if (type == error_mark_node)
6979     return;
6980
6981   if (TREE_CODE (type) == FUNCTION_TYPE
6982       && type_quals != TYPE_UNQUALIFIED)
6983     {
6984       /* This was an error in C++98 (cv-qualifiers cannot be added to
6985          a function type), but DR 295 makes the code well-formed by
6986          dropping the extra qualifiers. */
6987       if (pedantic)
6988         {
6989           tree bad_type = build_qualified_type (type, type_quals);
6990           pedwarn ("ignoring %qV qualifiers added to function type %qT",
6991                    bad_type, type);
6992         }
6993
6994       TREE_TYPE (decl) = TYPE_MAIN_VARIANT (type);
6995       return;
6996     }
6997
6998   /* Avoid setting TREE_READONLY incorrectly.  */
6999   if (/* If the object has a constructor, the constructor may modify
7000          the object.  */
7001       TYPE_NEEDS_CONSTRUCTING (type)
7002       /* If the type isn't complete, we don't know yet if it will need
7003          constructing.  */
7004       || !COMPLETE_TYPE_P (type)
7005       /* If the type has a mutable component, that component might be
7006          modified.  */
7007       || TYPE_HAS_MUTABLE_P (type))
7008     type_quals &= ~TYPE_QUAL_CONST;
7009
7010   c_apply_type_quals_to_decl (type_quals, decl);
7011 }
7012
7013 /* Subroutine of casts_away_constness.  Make T1 and T2 point at
7014    exemplar types such that casting T1 to T2 is casting away constness
7015    if and only if there is no implicit conversion from T1 to T2.  */
7016
7017 static void
7018 casts_away_constness_r (tree *t1, tree *t2)
7019 {
7020   int quals1;
7021   int quals2;
7022
7023   /* [expr.const.cast]
7024
7025      For multi-level pointer to members and multi-level mixed pointers
7026      and pointers to members (conv.qual), the "member" aspect of a
7027      pointer to member level is ignored when determining if a const
7028      cv-qualifier has been cast away.  */
7029   /* [expr.const.cast]
7030
7031      For  two  pointer types:
7032
7033             X1 is T1cv1,1 * ... cv1,N *   where T1 is not a pointer type
7034             X2 is T2cv2,1 * ... cv2,M *   where T2 is not a pointer type
7035             K is min(N,M)
7036
7037      casting from X1 to X2 casts away constness if, for a non-pointer
7038      type T there does not exist an implicit conversion (clause
7039      _conv_) from:
7040
7041             Tcv1,(N-K+1) * cv1,(N-K+2) * ... cv1,N *
7042
7043      to
7044
7045             Tcv2,(M-K+1) * cv2,(M-K+2) * ... cv2,M *.  */
7046   if ((!TYPE_PTR_P (*t1) && !TYPE_PTRMEM_P (*t1))
7047       || (!TYPE_PTR_P (*t2) && !TYPE_PTRMEM_P (*t2)))
7048     {
7049       *t1 = cp_build_qualified_type (void_type_node,
7050                                      cp_type_quals (*t1));
7051       *t2 = cp_build_qualified_type (void_type_node,
7052                                      cp_type_quals (*t2));
7053       return;
7054     }
7055
7056   quals1 = cp_type_quals (*t1);
7057   quals2 = cp_type_quals (*t2);
7058
7059   if (TYPE_PTRMEM_P (*t1))
7060     *t1 = TYPE_PTRMEM_POINTED_TO_TYPE (*t1);
7061   else
7062     *t1 = TREE_TYPE (*t1);
7063   if (TYPE_PTRMEM_P (*t2))
7064     *t2 = TYPE_PTRMEM_POINTED_TO_TYPE (*t2);
7065   else
7066     *t2 = TREE_TYPE (*t2);
7067
7068   casts_away_constness_r (t1, t2);
7069   *t1 = build_pointer_type (*t1);
7070   *t2 = build_pointer_type (*t2);
7071   *t1 = cp_build_qualified_type (*t1, quals1);
7072   *t2 = cp_build_qualified_type (*t2, quals2);
7073 }
7074
7075 /* Returns nonzero if casting from TYPE1 to TYPE2 casts away
7076    constness.  */
7077
7078 static bool
7079 casts_away_constness (tree t1, tree t2)
7080 {
7081   if (TREE_CODE (t2) == REFERENCE_TYPE)
7082     {
7083       /* [expr.const.cast]
7084
7085          Casting from an lvalue of type T1 to an lvalue of type T2
7086          using a reference cast casts away constness if a cast from an
7087          rvalue of type "pointer to T1" to the type "pointer to T2"
7088          casts away constness.  */
7089       t1 = (TREE_CODE (t1) == REFERENCE_TYPE ? TREE_TYPE (t1) : t1);
7090       return casts_away_constness (build_pointer_type (t1),
7091                                    build_pointer_type (TREE_TYPE (t2)));
7092     }
7093
7094   if (TYPE_PTRMEM_P (t1) && TYPE_PTRMEM_P (t2))
7095     /* [expr.const.cast]
7096
7097        Casting from an rvalue of type "pointer to data member of X
7098        of type T1" to the type "pointer to data member of Y of type
7099        T2" casts away constness if a cast from an rvalue of type
7100        "pointer to T1" to the type "pointer to T2" casts away
7101        constness.  */
7102     return casts_away_constness
7103       (build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (t1)),
7104        build_pointer_type (TYPE_PTRMEM_POINTED_TO_TYPE (t2)));
7105
7106   /* Casting away constness is only something that makes sense for
7107      pointer or reference types.  */
7108   if (TREE_CODE (t1) != POINTER_TYPE
7109       || TREE_CODE (t2) != POINTER_TYPE)
7110     return false;
7111
7112   /* Top-level qualifiers don't matter.  */
7113   t1 = TYPE_MAIN_VARIANT (t1);
7114   t2 = TYPE_MAIN_VARIANT (t2);
7115   casts_away_constness_r (&t1, &t2);
7116   if (!can_convert (t2, t1))
7117     return true;
7118
7119   return false;
7120 }
7121
7122 /* If T is a REFERENCE_TYPE return the type to which T refers.
7123    Otherwise, return T itself.  */
7124
7125 tree
7126 non_reference (tree t)
7127 {
7128   if (TREE_CODE (t) == REFERENCE_TYPE)
7129     t = TREE_TYPE (t);
7130   return t;
7131 }
7132
7133
7134 /* Return nonzero if REF is an lvalue valid for this language;
7135    otherwise, print an error message and return zero.  USE says
7136    how the lvalue is being used and so selects the error message.  */
7137
7138 int
7139 lvalue_or_else (const_tree ref, enum lvalue_use use)
7140 {
7141   int win = lvalue_p (ref);
7142
7143   if (!win)
7144     lvalue_error (use);
7145
7146   return win;
7147 }