gcc/c-typeck.c

   1 /* Build expressions with type checking for C compiler.
   2    Copyright (C) 1987, 1988, 1991, 1992, 1993, 1994, 1995, 1996, 1997,
   3    1998, 1999, 2000, 2001 Free Software Foundation, Inc.
   4
   5 This file is part of GNU CC.
   6
   7 GNU CC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU CC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU CC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22
  23 /* This file is part of the C front end.
  24    It contains routines to build C expressions given their operands,
  25    including computing the types of the result, C-specific error checks,
  26    and some optimization.
  27
  28    There are also routines to build RETURN_STMT nodes and CASE_STMT nodes,
  29    and to process initializations in declarations (since they work
  30    like a strange sort of assignment).  */
  31
  32 #include "config.h"
  33 #include "system.h"
  34 #include "tree.h"
  35 #include "c-tree.h"
  36 #include "tm_p.h"
  37 #include "flags.h"
  38 #include "output.h"
  39 #include "rtl.h"
  40 #include "expr.h"
  41 #include "toplev.h"
  42 #include "intl.h"
  43 #include "ggc.h"
  44
  45 /* Nonzero if we've already printed a "missing braces around initializer"
  46    message within this initializer.  */
  47 static int missing_braces_mentioned;
  48
  49 /* 1 if we explained undeclared var errors.  */
  50 static int undeclared_variable_notice;
  51
  52 static tree qualify_type                PARAMS ((tree, tree));
  53 static int comp_target_types            PARAMS ((tree, tree));
  54 static int function_types_compatible_p  PARAMS ((tree, tree));
  55 static int type_lists_compatible_p      PARAMS ((tree, tree));
  56 static tree decl_constant_value_for_broken_optimization PARAMS ((tree));
  57 static tree lookup_field                PARAMS ((tree, tree, tree *));
  58 static tree convert_arguments           PARAMS ((tree, tree, tree, tree));
  59 static tree pointer_int_sum             PARAMS ((enum tree_code, tree, tree));
  60 static tree pointer_diff                PARAMS ((tree, tree));
  61 static tree unary_complex_lvalue        PARAMS ((enum tree_code, tree));
  62 static void pedantic_lvalue_warning     PARAMS ((enum tree_code));
  63 static tree internal_build_compound_expr PARAMS ((tree, int));
  64 static tree convert_for_assignment      PARAMS ((tree, tree, const char *,
  65                                                  tree, tree, int));
  66 static void warn_for_assignment         PARAMS ((const char *, const char *,
  67                                                  tree, int));
  68 static tree valid_compound_expr_initializer PARAMS ((tree, tree));
  69 static void push_string                 PARAMS ((const char *));
  70 static void push_member_name            PARAMS ((tree));
  71 static void push_array_bounds           PARAMS ((int));
  72 static int spelling_length              PARAMS ((void));
  73 static char *print_spelling             PARAMS ((char *));
  74 static void warning_init                PARAMS ((const char *));
  75 static tree digest_init                 PARAMS ((tree, tree, int, int));
  76 static void output_init_element         PARAMS ((tree, tree, tree, int));
  77 static void output_pending_init_elements PARAMS ((int));
  78 static int set_designator               PARAMS ((int));
  79 static void push_range_stack            PARAMS ((tree));
  80 static void add_pending_init            PARAMS ((tree, tree));
  81 static void set_nonincremental_init     PARAMS ((void));
  82 static void set_nonincremental_init_from_string PARAMS ((tree));
  83 static tree find_init_member            PARAMS ((tree));
  84 \f
  85 /* Do `exp = require_complete_type (exp);' to make sure exp
  86    does not have an incomplete type.  (That includes void types.)  */
  87
  88 tree
  89 require_complete_type (value)
  90      tree value;
  91 {
  92   tree type = TREE_TYPE (value);
  93
  94   if (TREE_CODE (value) == ERROR_MARK)
  95     return error_mark_node;
  96
  97   /* First, detect a valid value with a complete type.  */
  98   if (COMPLETE_TYPE_P (type))
  99     return value;
 100
 101   incomplete_type_error (value, type);
 102   return error_mark_node;
 103 }
 104
 105 /* Print an error message for invalid use of an incomplete type.
 106    VALUE is the expression that was used (or 0 if that isn't known)
 107    and TYPE is the type that was invalid.  */
 108
 109 void
 110 incomplete_type_error (value, type)
 111      tree value;
 112      tree type;
 113 {
 114   const char *type_code_string;
 115
 116   /* Avoid duplicate error message.  */
 117   if (TREE_CODE (type) == ERROR_MARK)
 118     return;
 119
 120   if (value != 0 && (TREE_CODE (value) == VAR_DECL
 121                      || TREE_CODE (value) == PARM_DECL))
 122     error ("`%s' has an incomplete type",
 123            IDENTIFIER_POINTER (DECL_NAME (value)));
 124   else
 125     {
 126     retry:
 127       /* We must print an error message.  Be clever about what it says.  */
 128
 129       switch (TREE_CODE (type))
 130         {
 131         case RECORD_TYPE:
 132           type_code_string = "struct";
 133           break;
 134
 135         case UNION_TYPE:
 136           type_code_string = "union";
 137           break;
 138
 139         case ENUMERAL_TYPE:
 140           type_code_string = "enum";
 141           break;
 142
 143         case VOID_TYPE:
 144           error ("invalid use of void expression");
 145           return;
 146
 147         case ARRAY_TYPE:
 148           if (TYPE_DOMAIN (type))
 149             {
 150               type = TREE_TYPE (type);
 151               goto retry;
 152             }
 153           error ("invalid use of array with unspecified bounds");
 154           return;
 155
 156         default:
 157           abort ();
 158         }
 159
 160       if (TREE_CODE (TYPE_NAME (type)) == IDENTIFIER_NODE)
 161         error ("invalid use of undefined type `%s %s'",
 162                type_code_string, IDENTIFIER_POINTER (TYPE_NAME (type)));
 163       else
 164         /* If this type has a typedef-name, the TYPE_NAME is a TYPE_DECL.  */
 165         error ("invalid use of incomplete typedef `%s'",
 166                IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (type))));
 167     }
 168 }
 169
 170 /* Return a variant of TYPE which has all the type qualifiers of LIKE
 171    as well as those of TYPE.  */
 172
 173 static tree
 174 qualify_type (type, like)
 175      tree type, like;
 176 {
 177   return c_build_qualified_type (type,
 178                                  TYPE_QUALS (type) | TYPE_QUALS (like));
 179 }
 180 \f
 181 /* Return the common type of two types.
 182    We assume that comptypes has already been done and returned 1;
 183    if that isn't so, this may crash.  In particular, we assume that qualifiers
 184    match.
 185
 186    This is the type for the result of most arithmetic operations
 187    if the operands have the given two types.  */
 188
 189 tree
 190 common_type (t1, t2)
 191      tree t1, t2;
 192 {
 193   register enum tree_code code1;
 194   register enum tree_code code2;
 195   tree attributes;
 196
 197   /* Save time if the two types are the same.  */
 198
 199   if (t1 == t2) return t1;
 200
 201   /* If one type is nonsense, use the other.  */
 202   if (t1 == error_mark_node)
 203     return t2;
 204   if (t2 == error_mark_node)
 205     return t1;
 206
 207   /* Merge the attributes.  */
 208   attributes = merge_machine_type_attributes (t1, t2);
 209
 210   /* Treat an enum type as the unsigned integer type of the same width.  */
 211
 212   if (TREE_CODE (t1) == ENUMERAL_TYPE)
 213     t1 = type_for_size (TYPE_PRECISION (t1), 1);
 214   if (TREE_CODE (t2) == ENUMERAL_TYPE)
 215     t2 = type_for_size (TYPE_PRECISION (t2), 1);
 216
 217   code1 = TREE_CODE (t1);
 218   code2 = TREE_CODE (t2);
 219
 220   /* If one type is complex, form the common type of the non-complex
 221      components, then make that complex.  Use T1 or T2 if it is the
 222      required type.  */
 223   if (code1 == COMPLEX_TYPE || code2 == COMPLEX_TYPE)
 224     {
 225       tree subtype1 = code1 == COMPLEX_TYPE ? TREE_TYPE (t1) : t1;
 226       tree subtype2 = code2 == COMPLEX_TYPE ? TREE_TYPE (t2) : t2;
 227       tree subtype = common_type (subtype1, subtype2);
 228
 229       if (code1 == COMPLEX_TYPE && TREE_TYPE (t1) == subtype)
 230         return build_type_attribute_variant (t1, attributes);
 231       else if (code2 == COMPLEX_TYPE && TREE_TYPE (t2) == subtype)
 232         return build_type_attribute_variant (t2, attributes);
 233       else
 234         return build_type_attribute_variant (build_complex_type (subtype),
 235                                              attributes);
 236     }
 237
 238   switch (code1)
 239     {
 240     case INTEGER_TYPE:
 241     case REAL_TYPE:
 242       /* If only one is real, use it as the result.  */
 243
 244       if (code1 == REAL_TYPE && code2 != REAL_TYPE)
 245         return build_type_attribute_variant (t1, attributes);
 246
 247       if (code2 == REAL_TYPE && code1 != REAL_TYPE)
 248         return build_type_attribute_variant (t2, attributes);
 249
 250       /* Both real or both integers; use the one with greater precision.  */
 251
 252       if (TYPE_PRECISION (t1) > TYPE_PRECISION (t2))
 253         return build_type_attribute_variant (t1, attributes);
 254       else if (TYPE_PRECISION (t2) > TYPE_PRECISION (t1))
 255         return build_type_attribute_variant (t2, attributes);
 256
 257       /* Same precision.  Prefer longs to ints even when same size.  */
 258
 259       if (TYPE_MAIN_VARIANT (t1) == long_unsigned_type_node
 260           || TYPE_MAIN_VARIANT (t2) == long_unsigned_type_node)
 261         return build_type_attribute_variant (long_unsigned_type_node,
 262                                              attributes);
 263
 264       if (TYPE_MAIN_VARIANT (t1) == long_integer_type_node
 265           || TYPE_MAIN_VARIANT (t2) == long_integer_type_node)
 266         {
 267           /* But preserve unsignedness from the other type,
 268              since long cannot hold all the values of an unsigned int.  */
 269           if (TREE_UNSIGNED (t1) || TREE_UNSIGNED (t2))
 270              t1 = long_unsigned_type_node;
 271           else
 272              t1 = long_integer_type_node;
 273           return build_type_attribute_variant (t1, attributes);
 274         }
 275
 276       /* Likewise, prefer long double to double even if same size.  */
 277       if (TYPE_MAIN_VARIANT (t1) == long_double_type_node
 278           || TYPE_MAIN_VARIANT (t2) == long_double_type_node)
 279         return build_type_attribute_variant (long_double_type_node,
 280                                              attributes);
 281
 282       /* Otherwise prefer the unsigned one.  */
 283
 284       if (TREE_UNSIGNED (t1))
 285         return build_type_attribute_variant (t1, attributes);
 286       else
 287         return build_type_attribute_variant (t2, attributes);
 288
 289     case POINTER_TYPE:
 290       /* For two pointers, do this recursively on the target type,
 291          and combine the qualifiers of the two types' targets.  */
 292       /* This code was turned off; I don't know why.
 293          But ANSI C specifies doing this with the qualifiers.
 294          So I turned it on again.  */
 295       {
 296         tree pointed_to_1 = TREE_TYPE (t1);
 297         tree pointed_to_2 = TREE_TYPE (t2);
 298         tree target = common_type (TYPE_MAIN_VARIANT (pointed_to_1),
 299                                    TYPE_MAIN_VARIANT (pointed_to_2));
 300         t1 = build_pointer_type (c_build_qualified_type
 301                                  (target,
 302                                   TYPE_QUALS (pointed_to_1) |
 303                                   TYPE_QUALS (pointed_to_2)));
 304         return build_type_attribute_variant (t1, attributes);
 305       }
 306 #if 0
 307       t1 = build_pointer_type (common_type (TREE_TYPE (t1), TREE_TYPE (t2)));
 308       return build_type_attribute_variant (t1, attributes);
 309 #endif
 310
 311     case ARRAY_TYPE:
 312       {
 313         tree elt = common_type (TREE_TYPE (t1), TREE_TYPE (t2));
 314         /* Save space: see if the result is identical to one of the args.  */
 315         if (elt == TREE_TYPE (t1) && TYPE_DOMAIN (t1))
 316           return build_type_attribute_variant (t1, attributes);
 317         if (elt == TREE_TYPE (t2) && TYPE_DOMAIN (t2))
 318           return build_type_attribute_variant (t2, attributes);
 319         /* Merge the element types, and have a size if either arg has one.  */
 320         t1 = build_array_type (elt, TYPE_DOMAIN (TYPE_DOMAIN (t1) ? t1 : t2));
 321         return build_type_attribute_variant (t1, attributes);
 322       }
 323
 324     case FUNCTION_TYPE:
 325       /* Function types: prefer the one that specified arg types.
 326          If both do, merge the arg types.  Also merge the return types.  */
 327       {
 328         tree valtype = common_type (TREE_TYPE (t1), TREE_TYPE (t2));
 329         tree p1 = TYPE_ARG_TYPES (t1);
 330         tree p2 = TYPE_ARG_TYPES (t2);
 331         int len;
 332         tree newargs, n;
 333         int i;
 334
 335         /* Save space: see if the result is identical to one of the args.  */
 336         if (valtype == TREE_TYPE (t1) && ! TYPE_ARG_TYPES (t2))
 337           return build_type_attribute_variant (t1, attributes);
 338         if (valtype == TREE_TYPE (t2) && ! TYPE_ARG_TYPES (t1))
 339           return build_type_attribute_variant (t2, attributes);
 340
 341         /* Simple way if one arg fails to specify argument types.  */
 342         if (TYPE_ARG_TYPES (t1) == 0)
 343          {
 344            t1 = build_function_type (valtype, TYPE_ARG_TYPES (t2));
 345            return build_type_attribute_variant (t1, attributes);
 346          }
 347         if (TYPE_ARG_TYPES (t2) == 0)
 348          {
 349            t1 = build_function_type (valtype, TYPE_ARG_TYPES (t1));
 350            return build_type_attribute_variant (t1, attributes);
 351          }
 352
 353         /* If both args specify argument types, we must merge the two
 354            lists, argument by argument.  */
 355
 356         pushlevel (0);
 357         declare_parm_level (1);
 358
 359         len = list_length (p1);
 360         newargs = 0;
 361
 362         for (i = 0; i < len; i++)
 363           newargs = tree_cons (NULL_TREE, NULL_TREE, newargs);
 364
 365         n = newargs;
 366
 367         for (; p1;
 368              p1 = TREE_CHAIN (p1), p2 = TREE_CHAIN (p2), n = TREE_CHAIN (n))
 369           {
 370             /* A null type means arg type is not specified.
 371                Take whatever the other function type has.  */
 372             if (TREE_VALUE (p1) == 0)
 373               {
 374                 TREE_VALUE (n) = TREE_VALUE (p2);
 375                 goto parm_done;
 376               }
 377             if (TREE_VALUE (p2) == 0)
 378               {
 379                 TREE_VALUE (n) = TREE_VALUE (p1);
 380                 goto parm_done;
 381               }
 382
 383             /* Given  wait (union {union wait *u; int *i} *)
 384                and  wait (union wait *),
 385                prefer  union wait *  as type of parm.  */
 386             if (TREE_CODE (TREE_VALUE (p1)) == UNION_TYPE
 387                 && TREE_VALUE (p1) != TREE_VALUE (p2))
 388               {
 389                 tree memb;
 390                 for (memb = TYPE_FIELDS (TREE_VALUE (p1));
 391                      memb; memb = TREE_CHAIN (memb))
 392                   if (comptypes (TREE_TYPE (memb), TREE_VALUE (p2)))
 393                     {
 394                       TREE_VALUE (n) = TREE_VALUE (p2);
 395                       if (pedantic)
 396                         pedwarn ("function types not truly compatible in ISO C");
 397                       goto parm_done;
 398                     }
 399               }
 400             if (TREE_CODE (TREE_VALUE (p2)) == UNION_TYPE
 401                 && TREE_VALUE (p2) != TREE_VALUE (p1))
 402               {
 403                 tree memb;
 404                 for (memb = TYPE_FIELDS (TREE_VALUE (p2));
 405                      memb; memb = TREE_CHAIN (memb))
 406                   if (comptypes (TREE_TYPE (memb), TREE_VALUE (p1)))
 407                     {
 408                       TREE_VALUE (n) = TREE_VALUE (p1);
 409                       if (pedantic)
 410                         pedwarn ("function types not truly compatible in ISO C");
 411                       goto parm_done;
 412                     }
 413               }
 414             TREE_VALUE (n) = common_type (TREE_VALUE (p1), TREE_VALUE (p2));
 415           parm_done: ;
 416           }
 417
 418         poplevel (0, 0, 0);
 419
 420         t1 = build_function_type (valtype, newargs);
 421         /* ... falls through ...  */
 422       }
 423
 424     default:
 425       return build_type_attribute_variant (t1, attributes);
 426     }
 427
 428 }
 429 \f
 430 /* Return 1 if TYPE1 and TYPE2 are compatible types for assignment
 431    or various other operations.  Return 2 if they are compatible
 432    but a warning may be needed if you use them together.  */
 433
 434 int
 435 comptypes (type1, type2)
 436      tree type1, type2;
 437 {
 438   register tree t1 = type1;
 439   register tree t2 = type2;
 440   int attrval, val;
 441
 442   /* Suppress errors caused by previously reported errors.  */
 443
 444   if (t1 == t2 || !t1 || !t2
 445       || TREE_CODE (t1) == ERROR_MARK || TREE_CODE (t2) == ERROR_MARK)
 446     return 1;
 447
 448   /* If either type is the internal version of sizetype, return the
 449      language version.  */
 450   if (TREE_CODE (t1) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t1)
 451       && TYPE_DOMAIN (t1) != 0)
 452     t1 = TYPE_DOMAIN (t1);
 453
 454   if (TREE_CODE (t2) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t2)
 455       && TYPE_DOMAIN (t2) != 0)
 456     t2 = TYPE_DOMAIN (t2);
 457
 458   /* Treat an enum type as the integer type of the same width and
 459      signedness.  */
 460
 461   if (TREE_CODE (t1) == ENUMERAL_TYPE)
 462     t1 = type_for_size (TYPE_PRECISION (t1), TREE_UNSIGNED (t1));
 463   if (TREE_CODE (t2) == ENUMERAL_TYPE)
 464     t2 = type_for_size (TYPE_PRECISION (t2), TREE_UNSIGNED (t2));
 465
 466   if (t1 == t2)
 467     return 1;
 468
 469   /* Different classes of types can't be compatible.  */
 470
 471   if (TREE_CODE (t1) != TREE_CODE (t2)) return 0;
 472
 473   /* Qualifiers must match.  */
 474
 475   if (TYPE_QUALS (t1) != TYPE_QUALS (t2))
 476     return 0;
 477
 478   /* Allow for two different type nodes which have essentially the same
 479      definition.  Note that we already checked for equality of the type
 480      qualifiers (just above).  */
 481
 482   if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
 483     return 1;
 484
 485 #ifndef COMP_TYPE_ATTRIBUTES
 486 #define COMP_TYPE_ATTRIBUTES(t1,t2)     1
 487 #endif
 488
 489   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
 490   if (! (attrval = COMP_TYPE_ATTRIBUTES (t1, t2)))
 491      return 0;
 492
 493   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
 494   val = 0;
 495
 496   switch (TREE_CODE (t1))
 497     {
 498     case POINTER_TYPE:
 499       val = (TREE_TYPE (t1) == TREE_TYPE (t2)
 500               ? 1 : comptypes (TREE_TYPE (t1), TREE_TYPE (t2)));
 501       break;
 502
 503     case FUNCTION_TYPE:
 504       val = function_types_compatible_p (t1, t2);
 505       break;
 506
 507     case ARRAY_TYPE:
 508       {
 509         tree d1 = TYPE_DOMAIN (t1);
 510         tree d2 = TYPE_DOMAIN (t2);
 511         val = 1;
 512
 513         /* Target types must match incl. qualifiers.  */
 514         if (TREE_TYPE (t1) != TREE_TYPE (t2)
 515             && 0 == (val = comptypes (TREE_TYPE (t1), TREE_TYPE (t2))))
 516           return 0;
 517
 518         /* Sizes must match unless one is missing or variable.  */
 519         if (d1 == 0 || d2 == 0 || d1 == d2
 520             || TREE_CODE (TYPE_MIN_VALUE (d1)) != INTEGER_CST
 521             || TREE_CODE (TYPE_MIN_VALUE (d2)) != INTEGER_CST
 522             || TREE_CODE (TYPE_MAX_VALUE (d1)) != INTEGER_CST
 523             || TREE_CODE (TYPE_MAX_VALUE (d2)) != INTEGER_CST)
 524           break;
 525
 526         if (! tree_int_cst_equal (TYPE_MIN_VALUE (d1), TYPE_MIN_VALUE (d2))
 527             || ! tree_int_cst_equal (TYPE_MAX_VALUE (d1), TYPE_MAX_VALUE (d2)))
 528           val = 0;
 529
 530         break;
 531       }
 532
 533     case RECORD_TYPE:
 534       if (maybe_objc_comptypes (t1, t2, 0) == 1)
 535         val = 1;
 536       break;
 537
 538     default:
 539       break;
 540     }
 541   return attrval == 2 && val == 1 ? 2 : val;
 542 }
 543
 544 /* Return 1 if TTL and TTR are pointers to types that are equivalent,
 545    ignoring their qualifiers.  */
 546
 547 static int
 548 comp_target_types (ttl, ttr)
 549      tree ttl, ttr;
 550 {
 551   int val;
 552
 553   /* Give maybe_objc_comptypes a crack at letting these types through.  */
 554   if ((val = maybe_objc_comptypes (ttl, ttr, 1)) >= 0)
 555     return val;
 556
 557   val = comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (ttl)),
 558                    TYPE_MAIN_VARIANT (TREE_TYPE (ttr)));
 559
 560   if (val == 2 && pedantic)
 561     pedwarn ("types are not quite compatible");
 562   return val;
 563 }
 564 \f
 565 /* Subroutines of `comptypes'.  */
 566
 567 /* Return 1 if two function types F1 and F2 are compatible.
 568    If either type specifies no argument types,
 569    the other must specify a fixed number of self-promoting arg types.
 570    Otherwise, if one type specifies only the number of arguments,
 571    the other must specify that number of self-promoting arg types.
 572    Otherwise, the argument types must match.  */
 573
 574 static int
 575 function_types_compatible_p (f1, f2)
 576      tree f1, f2;
 577 {
 578   tree args1, args2;
 579   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
 580   int val = 1;
 581   int val1;
 582
 583   if (!(TREE_TYPE (f1) == TREE_TYPE (f2)
 584         || (val = comptypes (TREE_TYPE (f1), TREE_TYPE (f2)))))
 585     return 0;
 586
 587   args1 = TYPE_ARG_TYPES (f1);
 588   args2 = TYPE_ARG_TYPES (f2);
 589
 590   /* An unspecified parmlist matches any specified parmlist
 591      whose argument types don't need default promotions.  */
 592
 593   if (args1 == 0)
 594     {
 595       if (!self_promoting_args_p (args2))
 596         return 0;
 597       /* If one of these types comes from a non-prototype fn definition,
 598          compare that with the other type's arglist.
 599          If they don't match, ask for a warning (but no error).  */
 600       if (TYPE_ACTUAL_ARG_TYPES (f1)
 601           && 1 != type_lists_compatible_p (args2, TYPE_ACTUAL_ARG_TYPES (f1)))
 602         val = 2;
 603       return val;
 604     }
 605   if (args2 == 0)
 606     {
 607       if (!self_promoting_args_p (args1))
 608         return 0;
 609       if (TYPE_ACTUAL_ARG_TYPES (f2)
 610           && 1 != type_lists_compatible_p (args1, TYPE_ACTUAL_ARG_TYPES (f2)))
 611         val = 2;
 612       return val;
 613     }
 614
 615   /* Both types have argument lists: compare them and propagate results.  */
 616   val1 = type_lists_compatible_p (args1, args2);
 617   return val1 != 1 ? val1 : val;
 618 }
 619
 620 /* Check two lists of types for compatibility,
 621    returning 0 for incompatible, 1 for compatible,
 622    or 2 for compatible with warning.  */
 623
 624 static int
 625 type_lists_compatible_p (args1, args2)
 626      tree args1, args2;
 627 {
 628   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
 629   int val = 1;
 630   int newval = 0;
 631
 632   while (1)
 633     {
 634       if (args1 == 0 && args2 == 0)
 635         return val;
 636       /* If one list is shorter than the other,
 637          they fail to match.  */
 638       if (args1 == 0 || args2 == 0)
 639         return 0;
 640       /* A null pointer instead of a type
 641          means there is supposed to be an argument
 642          but nothing is specified about what type it has.
 643          So match anything that self-promotes.  */
 644       if (TREE_VALUE (args1) == 0)
 645         {
 646           if (simple_type_promotes_to (TREE_VALUE (args2)) != NULL_TREE)
 647             return 0;
 648         }
 649       else if (TREE_VALUE (args2) == 0)
 650         {
 651           if (simple_type_promotes_to (TREE_VALUE (args1)) != NULL_TREE)
 652             return 0;
 653         }
 654       else if (! (newval = comptypes (TREE_VALUE (args1), TREE_VALUE (args2))))
 655         {
 656           /* Allow  wait (union {union wait *u; int *i} *)
 657              and  wait (union wait *)  to be compatible.  */
 658           if (TREE_CODE (TREE_VALUE (args1)) == UNION_TYPE
 659               && (TYPE_NAME (TREE_VALUE (args1)) == 0
 660                   || TYPE_TRANSPARENT_UNION (TREE_VALUE (args1)))
 661               && TREE_CODE (TYPE_SIZE (TREE_VALUE (args1))) == INTEGER_CST
 662               && tree_int_cst_equal (TYPE_SIZE (TREE_VALUE (args1)),
 663                                      TYPE_SIZE (TREE_VALUE (args2))))
 664             {
 665               tree memb;
 666               for (memb = TYPE_FIELDS (TREE_VALUE (args1));
 667                    memb; memb = TREE_CHAIN (memb))
 668                 if (comptypes (TREE_TYPE (memb), TREE_VALUE (args2)))
 669                   break;
 670               if (memb == 0)
 671                 return 0;
 672             }
 673           else if (TREE_CODE (TREE_VALUE (args2)) == UNION_TYPE
 674                    && (TYPE_NAME (TREE_VALUE (args2)) == 0
 675                        || TYPE_TRANSPARENT_UNION (TREE_VALUE (args2)))
 676                    && TREE_CODE (TYPE_SIZE (TREE_VALUE (args2))) == INTEGER_CST
 677                    && tree_int_cst_equal (TYPE_SIZE (TREE_VALUE (args2)),
 678                                           TYPE_SIZE (TREE_VALUE (args1))))
 679             {
 680               tree memb;
 681               for (memb = TYPE_FIELDS (TREE_VALUE (args2));
 682                    memb; memb = TREE_CHAIN (memb))
 683                 if (comptypes (TREE_TYPE (memb), TREE_VALUE (args1)))
 684                   break;
 685               if (memb == 0)
 686                 return 0;
 687             }
 688           else
 689             return 0;
 690         }
 691
 692       /* comptypes said ok, but record if it said to warn.  */
 693       if (newval > val)
 694         val = newval;
 695
 696       args1 = TREE_CHAIN (args1);
 697       args2 = TREE_CHAIN (args2);
 698     }
 699 }
 700 \f
 701 /* Compute the value of the `sizeof' operator.  */
 702
 703 tree
 704 c_sizeof (type)
 705      tree type;
 706 {
 707   enum tree_code code = TREE_CODE (type);
 708   tree size;
 709
 710   if (code == FUNCTION_TYPE)
 711     {
 712       if (pedantic || warn_pointer_arith)
 713         pedwarn ("sizeof applied to a function type");
 714       size = size_one_node;
 715     }
 716   else if (code == VOID_TYPE)
 717     {
 718       if (pedantic || warn_pointer_arith)
 719         pedwarn ("sizeof applied to a void type");
 720       size = size_one_node;
 721     }
 722   else if (code == ERROR_MARK)
 723     size = size_one_node;
 724   else if (!COMPLETE_TYPE_P (type))
 725     {
 726       error ("sizeof applied to an incomplete type");
 727       size = size_zero_node;
 728     }
 729   else
 730     /* Convert in case a char is more than one unit.  */
 731     size = size_binop (CEIL_DIV_EXPR, TYPE_SIZE_UNIT (type),
 732                        size_int (TYPE_PRECISION (char_type_node)
 733                                  / BITS_PER_UNIT));
 734
 735   /* SIZE will have an integer type with TYPE_IS_SIZETYPE set.
 736      TYPE_IS_SIZETYPE means that certain things (like overflow) will
 737      never happen.  However, this node should really have type
 738      `size_t', which is just a typedef for an ordinary integer type.  */
 739   return fold (build1 (NOP_EXPR, c_size_type_node, size));
 740 }
 741
 742 tree
 743 c_sizeof_nowarn (type)
 744      tree type;
 745 {
 746   enum tree_code code = TREE_CODE (type);
 747   tree size;
 748
 749   if (code == FUNCTION_TYPE || code == VOID_TYPE || code == ERROR_MARK)
 750     size = size_one_node;
 751   else if (!COMPLETE_TYPE_P (type))
 752     size = size_zero_node;
 753   else
 754     /* Convert in case a char is more than one unit.  */
 755     size = size_binop (CEIL_DIV_EXPR, TYPE_SIZE_UNIT (type),
 756                        size_int (TYPE_PRECISION (char_type_node)
 757                                  / BITS_PER_UNIT));
 758
 759   /* SIZE will have an integer type with TYPE_IS_SIZETYPE set.
 760      TYPE_IS_SIZETYPE means that certain things (like overflow) will
 761      never happen.  However, this node should really have type
 762      `size_t', which is just a typedef for an ordinary integer type.  */
 763   return fold (build1 (NOP_EXPR, c_size_type_node, size));
 764 }
 765
 766 /* Compute the size to increment a pointer by.  */
 767
 768 tree
 769 c_size_in_bytes (type)
 770      tree type;
 771 {
 772   enum tree_code code = TREE_CODE (type);
 773
 774   if (code == FUNCTION_TYPE || code == VOID_TYPE || code == ERROR_MARK)
 775     return size_one_node;
 776
 777   if (!COMPLETE_OR_VOID_TYPE_P (type))
 778     {
 779       error ("arithmetic on pointer to an incomplete type");
 780       return size_one_node;
 781     }
 782
 783   /* Convert in case a char is more than one unit.  */
 784   return size_binop (CEIL_DIV_EXPR, TYPE_SIZE_UNIT (type),
 785                      size_int (TYPE_PRECISION (char_type_node)
 786                                / BITS_PER_UNIT));
 787 }
 788
 789 /* Implement the __alignof keyword: Return the minimum required
 790    alignment of TYPE, measured in bytes.  */
 791
 792 tree
 793 c_alignof (type)
 794      tree type;
 795 {
 796   enum tree_code code = TREE_CODE (type);
 797   tree t;
 798
 799   if (code == FUNCTION_TYPE)
 800     t = size_int (FUNCTION_BOUNDARY / BITS_PER_UNIT);
 801   else if (code == VOID_TYPE || code == ERROR_MARK)
 802     t = size_one_node;
 803   else if (code == ERROR_MARK)
 804     t = size_one_node;
 805   else if (!COMPLETE_TYPE_P (type))
 806     {
 807       error ("__alignof__ applied to an incomplete type");
 808       t = size_zero_node;
 809     }
 810   else
 811     t = size_int (TYPE_ALIGN (type) / BITS_PER_UNIT);
 812
 813   return fold (build1 (NOP_EXPR, c_size_type_node, t));
 814 }
 815 \f
 816 /* Implement the __alignof keyword: Return the minimum required
 817    alignment of EXPR, measured in bytes.  For VAR_DECL's and
 818    FIELD_DECL's return DECL_ALIGN (which can be set from an
 819    "aligned" __attribute__ specification).  */
 820
 821 tree
 822 c_alignof_expr (expr)
 823      tree expr;
 824 {
 825   tree t;
 826
 827   if (TREE_CODE (expr) == VAR_DECL)
 828     t = size_int (DECL_ALIGN (expr) / BITS_PER_UNIT);
 829
 830   else if (TREE_CODE (expr) == COMPONENT_REF
 831            && DECL_C_BIT_FIELD (TREE_OPERAND (expr, 1)))
 832     {
 833       error ("`__alignof' applied to a bit-field");
 834       t = size_one_node;
 835     }
 836   else if (TREE_CODE (expr) == COMPONENT_REF
 837       && TREE_CODE (TREE_OPERAND (expr, 1)) == FIELD_DECL)
 838     t = size_int (DECL_ALIGN (TREE_OPERAND (expr, 1)) / BITS_PER_UNIT);
 839
 840   else if (TREE_CODE (expr) == INDIRECT_REF)
 841     {
 842       tree t = TREE_OPERAND (expr, 0);
 843       tree best = t;
 844       int bestalign = TYPE_ALIGN (TREE_TYPE (TREE_TYPE (t)));
 845
 846       while (TREE_CODE (t) == NOP_EXPR
 847               && TREE_CODE (TREE_TYPE (TREE_OPERAND (t, 0))) == POINTER_TYPE)
 848         {
 849           int thisalign;
 850
 851           t = TREE_OPERAND (t, 0);
 852           thisalign = TYPE_ALIGN (TREE_TYPE (TREE_TYPE (t)));
 853           if (thisalign > bestalign)
 854             best = t, bestalign = thisalign;
 855         }
 856       return c_alignof (TREE_TYPE (TREE_TYPE (best)));
 857     }
 858   else
 859     return c_alignof (TREE_TYPE (expr));
 860
 861   return fold (build1 (NOP_EXPR, c_size_type_node, t));
 862 }
 863
 864 /* Return either DECL or its known constant value (if it has one).  */
 865
 866 tree
 867 decl_constant_value (decl)
 868      tree decl;
 869 {
 870   if (/* Don't change a variable array bound or initial value to a constant
 871          in a place where a variable is invalid.  */
 872       current_function_decl != 0
 873       && ! TREE_THIS_VOLATILE (decl)
 874       && TREE_READONLY (decl)
 875       && DECL_INITIAL (decl) != 0
 876       && TREE_CODE (DECL_INITIAL (decl)) != ERROR_MARK
 877       /* This is invalid if initial value is not constant.
 878          If it has either a function call, a memory reference,
 879          or a variable, then re-evaluating it could give different results.  */
 880       && TREE_CONSTANT (DECL_INITIAL (decl))
 881       /* Check for cases where this is sub-optimal, even though valid.  */
 882       && TREE_CODE (DECL_INITIAL (decl)) != CONSTRUCTOR)
 883     return DECL_INITIAL (decl);
 884   return decl;
 885 }
 886
 887 /* Return either DECL or its known constant value (if it has one), but
 888    return DECL if pedantic or DECL has mode BLKmode.  This is for
 889    bug-compatibility with the old behavior of decl_constant_value
 890    (before GCC 3.0); every use of this function is a bug and it should
 891    be removed before GCC 3.1.  It is not appropriate to use pedantic
 892    in a way that affects optimization, and BLKmode is probably not the
 893    right test for avoiding misoptimizations either.  */
 894
 895 static tree
 896 decl_constant_value_for_broken_optimization (decl)
 897      tree decl;
 898 {
 899   if (pedantic || DECL_MODE (decl) == BLKmode)
 900     return decl;
 901   else
 902     return decl_constant_value (decl);
 903 }
 904
 905 /* Perform default promotions for C data used in expressions.
 906    Arrays and functions are converted to pointers;
 907    enumeral types or short or char, to int.
 908    In addition, manifest constants symbols are replaced by their values.  */
 909
 910 tree
 911 default_conversion (exp)
 912      tree exp;
 913 {
 914   register tree type = TREE_TYPE (exp);
 915   register enum tree_code code = TREE_CODE (type);
 916
 917   /* Constants can be used directly unless they're not loadable.  */
 918   if (TREE_CODE (exp) == CONST_DECL)
 919     exp = DECL_INITIAL (exp);
 920
 921   /* Replace a nonvolatile const static variable with its value unless
 922      it is an array, in which case we must be sure that taking the
 923      address of the array produces consistent results.  */
 924   else if (optimize && TREE_CODE (exp) == VAR_DECL && code != ARRAY_TYPE)
 925     {
 926       exp = decl_constant_value_for_broken_optimization (exp);
 927       type = TREE_TYPE (exp);
 928     }
 929
 930   /* Strip NON_LVALUE_EXPRs and no-op conversions, since we aren't using as
 931      an lvalue.
 932
 933      Do not use STRIP_NOPS here!  It will remove conversions from pointer
 934      to integer and cause infinite recursion.  */
 935   while (TREE_CODE (exp) == NON_LVALUE_EXPR
 936          || (TREE_CODE (exp) == NOP_EXPR
 937              && TREE_TYPE (TREE_OPERAND (exp, 0)) == TREE_TYPE (exp)))
 938     exp = TREE_OPERAND (exp, 0);
 939
 940   /* Normally convert enums to int,
 941      but convert wide enums to something wider.  */
 942   if (code == ENUMERAL_TYPE)
 943     {
 944       type = type_for_size (MAX (TYPE_PRECISION (type),
 945                                  TYPE_PRECISION (integer_type_node)),
 946                             ((flag_traditional
 947                               || (TYPE_PRECISION (type)
 948                                   >= TYPE_PRECISION (integer_type_node)))
 949                              && TREE_UNSIGNED (type)));
 950
 951       return convert (type, exp);
 952     }
 953
 954   if (TREE_CODE (exp) == COMPONENT_REF
 955       && DECL_C_BIT_FIELD (TREE_OPERAND (exp, 1))
 956       /* If it's thinner than an int, promote it like a
 957          c_promoting_integer_type_p, otherwise leave it alone.  */
 958       && 0 > compare_tree_int (DECL_SIZE (TREE_OPERAND (exp, 1)),
 959                                TYPE_PRECISION (integer_type_node)))
 960     return convert (flag_traditional && TREE_UNSIGNED (type)
 961                     ? unsigned_type_node : integer_type_node,
 962                     exp);
 963
 964   if (c_promoting_integer_type_p (type))
 965     {
 966       /* Traditionally, unsignedness is preserved in default promotions.
 967          Also preserve unsignedness if not really getting any wider.  */
 968       if (TREE_UNSIGNED (type)
 969           && (flag_traditional
 970               || TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node)))
 971         return convert (unsigned_type_node, exp);
 972
 973       return convert (integer_type_node, exp);
 974     }
 975
 976   if (flag_traditional && !flag_allow_single_precision
 977       && TYPE_MAIN_VARIANT (type) == float_type_node)
 978     return convert (double_type_node, exp);
 979
 980   if (code == VOID_TYPE)
 981     {
 982       error ("void value not ignored as it ought to be");
 983       return error_mark_node;
 984     }
 985   if (code == FUNCTION_TYPE)
 986     {
 987       return build_unary_op (ADDR_EXPR, exp, 0);
 988     }
 989   if (code == ARRAY_TYPE)
 990     {
 991       register tree adr;
 992       tree restype = TREE_TYPE (type);
 993       tree ptrtype;
 994       int constp = 0;
 995       int volatilep = 0;
 996
 997       if (TREE_CODE_CLASS (TREE_CODE (exp)) == 'r' || DECL_P (exp))
 998         {
 999           constp = TREE_READONLY (exp);
1000           volatilep = TREE_THIS_VOLATILE (exp);
1001         }
1002
1003       if (TYPE_QUALS (type) || constp || volatilep)
1004         restype
1005           = c_build_qualified_type (restype,
1006                                     TYPE_QUALS (type)
1007                                     | (constp * TYPE_QUAL_CONST)
1008                                     | (volatilep * TYPE_QUAL_VOLATILE));
1009
1010       if (TREE_CODE (exp) == INDIRECT_REF)
1011         return convert (TYPE_POINTER_TO (restype),
1012                         TREE_OPERAND (exp, 0));
1013
1014       if (TREE_CODE (exp) == COMPOUND_EXPR)
1015         {
1016           tree op1 = default_conversion (TREE_OPERAND (exp, 1));
1017           return build (COMPOUND_EXPR, TREE_TYPE (op1),
1018                         TREE_OPERAND (exp, 0), op1);
1019         }
1020
1021       if (! lvalue_p (exp)
1022           && ! (TREE_CODE (exp) == CONSTRUCTOR && TREE_STATIC (exp)))
1023         {
1024           error ("invalid use of non-lvalue array");
1025           return error_mark_node;
1026         }
1027
1028       ptrtype = build_pointer_type (restype);
1029
1030       if (TREE_CODE (exp) == VAR_DECL)
1031         {
1032           /* ??? This is not really quite correct
1033              in that the type of the operand of ADDR_EXPR
1034              is not the target type of the type of the ADDR_EXPR itself.
1035              Question is, can this lossage be avoided?  */
1036           adr = build1 (ADDR_EXPR, ptrtype, exp);
1037           if (mark_addressable (exp) == 0)
1038             return error_mark_node;
1039           TREE_CONSTANT (adr) = staticp (exp);
1040           TREE_SIDE_EFFECTS (adr) = 0;   /* Default would be, same as EXP.  */
1041           return adr;
1042         }
1043       /* This way is better for a COMPONENT_REF since it can
1044          simplify the offset for a component.  */
1045       adr = build_unary_op (ADDR_EXPR, exp, 1);
1046       return convert (ptrtype, adr);
1047     }
1048   return exp;
1049 }
1050 \f
1051 /* Look up component name in the structure type definition.
1052
1053    If this component name is found indirectly within an anonymous union,
1054    store in *INDIRECT the component which directly contains
1055    that anonymous union.  Otherwise, set *INDIRECT to 0.  */
1056
1057 static tree
1058 lookup_field (type, component, indirect)
1059      tree type, component;
1060      tree *indirect;
1061 {
1062   tree field;
1063
1064   /* If TYPE_LANG_SPECIFIC is set, then it is a sorted array of pointers
1065      to the field elements.  Use a binary search on this array to quickly
1066      find the element.  Otherwise, do a linear search.  TYPE_LANG_SPECIFIC
1067      will always be set for structures which have many elements.  */
1068
1069   if (TYPE_LANG_SPECIFIC (type))
1070     {
1071       int bot, top, half;
1072       tree *field_array = &TYPE_LANG_SPECIFIC (type)->elts[0];
1073
1074       field = TYPE_FIELDS (type);
1075       bot = 0;
1076       top = TYPE_LANG_SPECIFIC (type)->len;
1077       while (top - bot > 1)
1078         {
1079           half = (top - bot + 1) >> 1;
1080           field = field_array[bot+half];
1081
1082           if (DECL_NAME (field) == NULL_TREE)
1083             {
1084               /* Step through all anon unions in linear fashion.  */
1085               while (DECL_NAME (field_array[bot]) == NULL_TREE)
1086                 {
1087                   tree anon = 0, junk;
1088
1089                   field = field_array[bot++];
1090                   if (TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
1091                       || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
1092                     anon = lookup_field (TREE_TYPE (field), component, &junk);
1093
1094                   if (anon != NULL_TREE)
1095                     {
1096                       *indirect = field;
1097                       return anon;
1098                     }
1099                 }
1100
1101               /* Entire record is only anon unions.  */
1102               if (bot > top)
1103                 return NULL_TREE;
1104
1105               /* Restart the binary search, with new lower bound.  */
1106               continue;
1107             }
1108
1109           if (DECL_NAME (field) == component)
1110             break;
1111           if (DECL_NAME (field) < component)
1112             bot += half;
1113           else
1114             top = bot + half;
1115         }
1116
1117       if (DECL_NAME (field_array[bot]) == component)
1118         field = field_array[bot];
1119       else if (DECL_NAME (field) != component)
1120         field = 0;
1121     }
1122   else
1123     {
1124       for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1125         {
1126           if (DECL_NAME (field) == NULL_TREE)
1127             {
1128               tree junk;
1129               tree anon = 0;
1130
1131               if (TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
1132                   || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
1133                 anon = lookup_field (TREE_TYPE (field), component, &junk);
1134
1135               if (anon != NULL_TREE)
1136                 {
1137                   *indirect = field;
1138                   return anon;
1139                 }
1140             }
1141
1142           if (DECL_NAME (field) == component)
1143             break;
1144         }
1145     }
1146
1147   *indirect = NULL_TREE;
1148   return field;
1149 }
1150
1151 /* Make an expression to refer to the COMPONENT field of
1152    structure or union value DATUM.  COMPONENT is an IDENTIFIER_NODE.  */
1153
1154 tree
1155 build_component_ref (datum, component)
1156      tree datum, component;
1157 {
1158   register tree type = TREE_TYPE (datum);
1159   register enum tree_code code = TREE_CODE (type);
1160   register tree field = NULL;
1161   register tree ref;
1162
1163   /* If DATUM is a COMPOUND_EXPR or COND_EXPR, move our reference inside it
1164      unless we are not to support things not strictly ANSI.  */
1165   switch (TREE_CODE (datum))
1166     {
1167     case COMPOUND_EXPR:
1168       {
1169         tree value = build_component_ref (TREE_OPERAND (datum, 1), component);
1170         return build (COMPOUND_EXPR, TREE_TYPE (value),
1171                       TREE_OPERAND (datum, 0), value);
1172       }
1173     case COND_EXPR:
1174       return build_conditional_expr
1175         (TREE_OPERAND (datum, 0),
1176          build_component_ref (TREE_OPERAND (datum, 1), component),
1177          build_component_ref (TREE_OPERAND (datum, 2), component));
1178
1179     default:
1180       break;
1181     }
1182
1183   /* See if there is a field or component with name COMPONENT.  */
1184
1185   if (code == RECORD_TYPE || code == UNION_TYPE)
1186     {
1187       tree indirect = 0;
1188
1189       if (!COMPLETE_TYPE_P (type))
1190         {
1191           incomplete_type_error (NULL_TREE, type);
1192           return error_mark_node;
1193         }
1194
1195       field = lookup_field (type, component, &indirect);
1196
1197       if (!field)
1198         {
1199           error ("%s has no member named `%s'",
1200                  code == RECORD_TYPE ? "structure" : "union",
1201                  IDENTIFIER_POINTER (component));
1202           return error_mark_node;
1203         }
1204       if (TREE_TYPE (field) == error_mark_node)
1205         return error_mark_node;
1206
1207       /* If FIELD was found buried within an anonymous union,
1208          make one COMPONENT_REF to get that anonymous union,
1209          then fall thru to make a second COMPONENT_REF to get FIELD.  */
1210       if (indirect != 0)
1211         {
1212           ref = build (COMPONENT_REF, TREE_TYPE (indirect), datum, indirect);
1213           if (TREE_READONLY (datum) || TREE_READONLY (indirect))
1214             TREE_READONLY (ref) = 1;
1215           if (TREE_THIS_VOLATILE (datum) || TREE_THIS_VOLATILE (indirect))
1216             TREE_THIS_VOLATILE (ref) = 1;
1217           datum = ref;
1218         }
1219
1220       ref = build (COMPONENT_REF, TREE_TYPE (field), datum, field);
1221
1222       if (TREE_READONLY (datum) || TREE_READONLY (field))
1223         TREE_READONLY (ref) = 1;
1224       if (TREE_THIS_VOLATILE (datum) || TREE_THIS_VOLATILE (field))
1225         TREE_THIS_VOLATILE (ref) = 1;
1226
1227       return ref;
1228     }
1229   else if (code != ERROR_MARK)
1230     error ("request for member `%s' in something not a structure or union",
1231             IDENTIFIER_POINTER (component));
1232
1233   return error_mark_node;
1234 }
1235 \f
1236 /* Given an expression PTR for a pointer, return an expression
1237    for the value pointed to.
1238    ERRORSTRING is the name of the operator to appear in error messages.  */
1239
1240 tree
1241 build_indirect_ref (ptr, errorstring)
1242      tree ptr;
1243      const char *errorstring;
1244 {
1245   register tree pointer = default_conversion (ptr);
1246   register tree type = TREE_TYPE (pointer);
1247
1248   if (TREE_CODE (type) == POINTER_TYPE)
1249     {
1250       if (TREE_CODE (pointer) == ADDR_EXPR
1251           && !flag_volatile
1252           && (TREE_TYPE (TREE_OPERAND (pointer, 0))
1253               == TREE_TYPE (type)))
1254         return TREE_OPERAND (pointer, 0);
1255       else
1256         {
1257           tree t = TREE_TYPE (type);
1258           register tree ref = build1 (INDIRECT_REF,
1259                                       TYPE_MAIN_VARIANT (t), pointer);
1260
1261           if (!COMPLETE_OR_VOID_TYPE_P (t) && TREE_CODE (t) != ARRAY_TYPE)
1262             {
1263               error ("dereferencing pointer to incomplete type");
1264               return error_mark_node;
1265             }
1266           if (VOID_TYPE_P (t) && skip_evaluation == 0)
1267             warning ("dereferencing `void *' pointer");
1268
1269           /* We *must* set TREE_READONLY when dereferencing a pointer to const,
1270              so that we get the proper error message if the result is used
1271              to assign to.  Also, &* is supposed to be a no-op.
1272              And ANSI C seems to specify that the type of the result
1273              should be the const type.  */
1274           /* A de-reference of a pointer to const is not a const.  It is valid
1275              to change it via some other pointer.  */
1276           TREE_READONLY (ref) = TYPE_READONLY (t);
1277           TREE_SIDE_EFFECTS (ref)
1278             = TYPE_VOLATILE (t) || TREE_SIDE_EFFECTS (pointer) || flag_volatile;
1279           TREE_THIS_VOLATILE (ref) = TYPE_VOLATILE (t);
1280           return ref;
1281         }
1282     }
1283   else if (TREE_CODE (pointer) != ERROR_MARK)
1284     error ("invalid type argument of `%s'", errorstring);
1285   return error_mark_node;
1286 }
1287
1288 /* This handles expressions of the form "a[i]", which denotes
1289    an array reference.
1290
1291    This is logically equivalent in C to *(a+i), but we may do it differently.
1292    If A is a variable or a member, we generate a primitive ARRAY_REF.
1293    This avoids forcing the array out of registers, and can work on
1294    arrays that are not lvalues (for example, members of structures returned
1295    by functions).  */
1296
1297 tree
1298 build_array_ref (array, index)
1299      tree array, index;
1300 {
1301   if (index == 0)
1302     {
1303       error ("subscript missing in array reference");
1304       return error_mark_node;
1305     }
1306
1307   if (TREE_TYPE (array) == error_mark_node
1308       || TREE_TYPE (index) == error_mark_node)
1309     return error_mark_node;
1310
1311   if (TREE_CODE (TREE_TYPE (array)) == ARRAY_TYPE
1312       && TREE_CODE (array) != INDIRECT_REF)
1313     {
1314       tree rval, type;
1315
1316       /* Subscripting with type char is likely to lose
1317          on a machine where chars are signed.
1318          So warn on any machine, but optionally.
1319          Don't warn for unsigned char since that type is safe.
1320          Don't warn for signed char because anyone who uses that
1321          must have done so deliberately.  */
1322       if (warn_char_subscripts
1323           && TYPE_MAIN_VARIANT (TREE_TYPE (index)) == char_type_node)
1324         warning ("array subscript has type `char'");
1325
1326       /* Apply default promotions *after* noticing character types.  */
1327       index = default_conversion (index);
1328
1329       /* Require integer *after* promotion, for sake of enums.  */
1330       if (TREE_CODE (TREE_TYPE (index)) != INTEGER_TYPE)
1331         {
1332           error ("array subscript is not an integer");
1333           return error_mark_node;
1334         }
1335
1336       /* An array that is indexed by a non-constant
1337          cannot be stored in a register; we must be able to do
1338          address arithmetic on its address.
1339          Likewise an array of elements of variable size.  */
1340       if (TREE_CODE (index) != INTEGER_CST
1341           || (COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (array)))
1342               && TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (array)))) != INTEGER_CST))
1343         {
1344           if (mark_addressable (array) == 0)
1345             return error_mark_node;
1346         }
1347       /* An array that is indexed by a constant value which is not within
1348          the array bounds cannot be stored in a register either; because we
1349          would get a crash in store_bit_field/extract_bit_field when trying
1350          to access a non-existent part of the register.  */
1351       if (TREE_CODE (index) == INTEGER_CST
1352           && TYPE_VALUES (TREE_TYPE (array))
1353           && ! int_fits_type_p (index, TYPE_VALUES (TREE_TYPE (array))))
1354         {
1355           if (mark_addressable (array) == 0)
1356             return error_mark_node;
1357         }
1358
1359       if (pedantic)
1360         {
1361           tree foo = array;
1362           while (TREE_CODE (foo) == COMPONENT_REF)
1363             foo = TREE_OPERAND (foo, 0);
1364           if (TREE_CODE (foo) == VAR_DECL && DECL_REGISTER (foo))
1365             pedwarn ("ISO C forbids subscripting `register' array");
1366           else if (! flag_isoc99 && ! lvalue_p (foo))
1367             pedwarn ("ISO C89 forbids subscripting non-lvalue array");
1368         }
1369
1370       type = TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (array)));
1371       rval = build (ARRAY_REF, type, array, index);
1372       /* Array ref is const/volatile if the array elements are
1373          or if the array is.  */
1374       TREE_READONLY (rval)
1375         |= (TYPE_READONLY (TREE_TYPE (TREE_TYPE (array)))
1376             | TREE_READONLY (array));
1377       TREE_SIDE_EFFECTS (rval)
1378         |= (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (array)))
1379             | TREE_SIDE_EFFECTS (array));
1380       TREE_THIS_VOLATILE (rval)
1381         |= (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (array)))
1382             /* This was added by rms on 16 Nov 91.
1383                It fixes  vol struct foo *a;  a->elts[1]
1384                in an inline function.
1385                Hope it doesn't break something else.  */
1386             | TREE_THIS_VOLATILE (array));
1387       return require_complete_type (fold (rval));
1388     }
1389
1390   {
1391     tree ar = default_conversion (array);
1392     tree ind = default_conversion (index);
1393
1394     /* Do the same warning check as above, but only on the part that's
1395        syntactically the index and only if it is also semantically
1396        the index.  */
1397     if (warn_char_subscripts
1398         && TREE_CODE (TREE_TYPE (index)) == INTEGER_TYPE
1399         && TYPE_MAIN_VARIANT (TREE_TYPE (index)) == char_type_node)
1400       warning ("subscript has type `char'");
1401
1402     /* Put the integer in IND to simplify error checking.  */
1403     if (TREE_CODE (TREE_TYPE (ar)) == INTEGER_TYPE)
1404       {
1405         tree temp = ar;
1406         ar = ind;
1407         ind = temp;
1408       }
1409
1410     if (ar == error_mark_node)
1411       return ar;
1412
1413     if (TREE_CODE (TREE_TYPE (ar)) != POINTER_TYPE
1414         || TREE_CODE (TREE_TYPE (TREE_TYPE (ar))) == FUNCTION_TYPE)
1415       {
1416         error ("subscripted value is neither array nor pointer");
1417         return error_mark_node;
1418       }
1419     if (TREE_CODE (TREE_TYPE (ind)) != INTEGER_TYPE)
1420       {
1421         error ("array subscript is not an integer");
1422         return error_mark_node;
1423       }
1424
1425     return build_indirect_ref (build_binary_op (PLUS_EXPR, ar, ind, 0),
1426                                "array indexing");
1427   }
1428 }
1429 \f
1430 /* Build an external reference to identifier ID.  FUN indicates
1431    whether this will be used for a function call.  */
1432 tree
1433 build_external_ref (id, fun)
1434      tree id;
1435      int fun;
1436 {
1437   tree ref;
1438   tree decl = lookup_name (id);
1439   tree objc_ivar = lookup_objc_ivar (id);
1440
1441   if (!decl || decl == error_mark_node || C_DECL_ANTICIPATED (decl))
1442     {
1443       if (objc_ivar)
1444         ref = objc_ivar;
1445       else if (fun)
1446         {
1447           if (!decl || decl == error_mark_node)
1448             /* Ordinary implicit function declaration.  */
1449             ref = implicitly_declare (id);
1450           else
1451             {
1452               /* Implicit declaration of built-in function.  Don't
1453                  change the built-in declaration, but don't let this
1454                  go by silently, either.  */
1455               implicit_decl_warning (id);
1456
1457               /* only issue this warning once */
1458               C_DECL_ANTICIPATED (decl) = 0;
1459               ref = decl;
1460             }
1461         }
1462       else
1463         {
1464           /* Reference to undeclared variable, including reference to
1465              builtin outside of function-call context.  */
1466           if (current_function_decl == 0)
1467             error ("`%s' undeclared here (not in a function)",
1468                    IDENTIFIER_POINTER (id));
1469           else
1470             {
1471               if (IDENTIFIER_GLOBAL_VALUE (id) != error_mark_node
1472                   || IDENTIFIER_ERROR_LOCUS (id) != current_function_decl)
1473                 {
1474                   error ("`%s' undeclared (first use in this function)",
1475                          IDENTIFIER_POINTER (id));
1476
1477                   if (! undeclared_variable_notice)
1478                     {
1479                       error ("(Each undeclared identifier is reported only once");
1480                       error ("for each function it appears in.)");
1481                       undeclared_variable_notice = 1;
1482                     }
1483                 }
1484               IDENTIFIER_GLOBAL_VALUE (id) = error_mark_node;
1485               IDENTIFIER_ERROR_LOCUS (id) = current_function_decl;
1486             }
1487           return error_mark_node;
1488         }
1489     }
1490   else
1491     {
1492       /* Properly declared variable or function reference.  */
1493       if (!objc_ivar)
1494         ref = decl;
1495       else if (decl != objc_ivar && IDENTIFIER_LOCAL_VALUE (id))
1496         {
1497           warning ("local declaration of `%s' hides instance variable",
1498                    IDENTIFIER_POINTER (id));
1499           ref = decl;
1500         }
1501       else
1502         ref = objc_ivar;
1503     }
1504
1505   if (TREE_TYPE (ref) == error_mark_node)
1506     return error_mark_node;
1507
1508   assemble_external (ref);
1509   TREE_USED (ref) = 1;
1510
1511   if (TREE_CODE (ref) == CONST_DECL)
1512     {
1513       ref = DECL_INITIAL (ref);
1514       TREE_CONSTANT (ref) = 1;
1515     }
1516
1517   return ref;
1518 }
1519
1520 /* Build a function call to function FUNCTION with parameters PARAMS.
1521    PARAMS is a list--a chain of TREE_LIST nodes--in which the
1522    TREE_VALUE of each node is a parameter-expression.
1523    FUNCTION's data type may be a function type or a pointer-to-function.  */
1524
1525 tree
1526 build_function_call (function, params)
1527      tree function, params;
1528 {
1529   register tree fntype, fundecl = 0;
1530   register tree coerced_params;
1531   tree name = NULL_TREE, assembler_name = NULL_TREE, result;
1532
1533   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
1534   STRIP_TYPE_NOPS (function);
1535
1536   /* Convert anything with function type to a pointer-to-function.  */
1537   if (TREE_CODE (function) == FUNCTION_DECL)
1538     {
1539       name = DECL_NAME (function);
1540       assembler_name = DECL_ASSEMBLER_NAME (function);
1541
1542       /* Differs from default_conversion by not setting TREE_ADDRESSABLE
1543          (because calling an inline function does not mean the function
1544          needs to be separately compiled).  */
1545       fntype = build_type_variant (TREE_TYPE (function),
1546                                    TREE_READONLY (function),
1547                                    TREE_THIS_VOLATILE (function));
1548       fundecl = function;
1549       function = build1 (ADDR_EXPR, build_pointer_type (fntype), function);
1550     }
1551   else
1552     function = default_conversion (function);
1553
1554   fntype = TREE_TYPE (function);
1555
1556   if (TREE_CODE (fntype) == ERROR_MARK)
1557     return error_mark_node;
1558
1559   if (!(TREE_CODE (fntype) == POINTER_TYPE
1560         && TREE_CODE (TREE_TYPE (fntype)) == FUNCTION_TYPE))
1561     {
1562       error ("called object is not a function");
1563       return error_mark_node;
1564     }
1565
1566   /* fntype now gets the type of function pointed to.  */
1567   fntype = TREE_TYPE (fntype);
1568
1569   /* Convert the parameters to the types declared in the
1570      function prototype, or apply default promotions.  */
1571
1572   coerced_params
1573     = convert_arguments (TYPE_ARG_TYPES (fntype), params, name, fundecl);
1574
1575   /* Check for errors in format strings.  */
1576
1577   if (warn_format && (name || assembler_name))
1578     check_function_format (NULL, name, assembler_name, coerced_params);
1579
1580   /* Recognize certain built-in functions so we can make tree-codes
1581      other than CALL_EXPR.  We do this when it enables fold-const.c
1582      to do something useful.  */
1583
1584   if (TREE_CODE (function) == ADDR_EXPR
1585       && TREE_CODE (TREE_OPERAND (function, 0)) == FUNCTION_DECL
1586       && DECL_BUILT_IN (TREE_OPERAND (function, 0)))
1587     {
1588       result = expand_tree_builtin (TREE_OPERAND (function, 0),
1589                                     params, coerced_params);
1590       if (result)
1591         return result;
1592     }
1593
1594   result = build (CALL_EXPR, TREE_TYPE (fntype),
1595                   function, coerced_params, NULL_TREE);
1596   TREE_SIDE_EFFECTS (result) = 1;
1597   result = fold (result);
1598
1599   if (VOID_TYPE_P (TREE_TYPE (result)))
1600     return result;
1601   return require_complete_type (result);
1602 }
1603 \f
1604 /* Convert the argument expressions in the list VALUES
1605    to the types in the list TYPELIST.  The result is a list of converted
1606    argument expressions.
1607
1608    If TYPELIST is exhausted, or when an element has NULL as its type,
1609    perform the default conversions.
1610
1611    PARMLIST is the chain of parm decls for the function being called.
1612    It may be 0, if that info is not available.
1613    It is used only for generating error messages.
1614
1615    NAME is an IDENTIFIER_NODE or 0.  It is used only for error messages.
1616
1617    This is also where warnings about wrong number of args are generated.
1618
1619    Both VALUES and the returned value are chains of TREE_LIST nodes
1620    with the elements of the list in the TREE_VALUE slots of those nodes.  */
1621
1622 static tree
1623 convert_arguments (typelist, values, name, fundecl)
1624      tree typelist, values, name, fundecl;
1625 {
1626   register tree typetail, valtail;
1627   register tree result = NULL;
1628   int parmnum;
1629
1630   /* Scan the given expressions and types, producing individual
1631      converted arguments and pushing them on RESULT in reverse order.  */
1632
1633   for (valtail = values, typetail = typelist, parmnum = 0;
1634        valtail;
1635        valtail = TREE_CHAIN (valtail), parmnum++)
1636     {
1637       register tree type = typetail ? TREE_VALUE (typetail) : 0;
1638       register tree val = TREE_VALUE (valtail);
1639
1640       if (type == void_type_node)
1641         {
1642           if (name)
1643             error ("too many arguments to function `%s'",
1644                    IDENTIFIER_POINTER (name));
1645           else
1646             error ("too many arguments to function");
1647           break;
1648         }
1649
1650       /* Strip NON_LVALUE_EXPRs since we aren't using as an lvalue.  */
1651       /* Do not use STRIP_NOPS here!  We do not want an enumerator with value 0
1652          to convert automatically to a pointer.  */
1653       if (TREE_CODE (val) == NON_LVALUE_EXPR)
1654         val = TREE_OPERAND (val, 0);
1655
1656       if (TREE_CODE (TREE_TYPE (val)) == ARRAY_TYPE
1657           || TREE_CODE (TREE_TYPE (val)) == FUNCTION_TYPE)
1658         val = default_conversion (val);
1659
1660       val = require_complete_type (val);
1661
1662       if (type != 0)
1663         {
1664           /* Formal parm type is specified by a function prototype.  */
1665           tree parmval;
1666
1667           if (!COMPLETE_TYPE_P (type))
1668             {
1669               error ("type of formal parameter %d is incomplete", parmnum + 1);
1670               parmval = val;
1671             }
1672           else
1673             {
1674               /* Optionally warn about conversions that
1675                  differ from the default conversions.  */
1676               if (warn_conversion || warn_traditional)
1677                 {
1678                   int formal_prec = TYPE_PRECISION (type);
1679
1680                   if (INTEGRAL_TYPE_P (type)
1681                       && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
1682                     warn_for_assignment ("%s as integer rather than floating due to prototype", (char *) 0, name, parmnum + 1);
1683                   if (INTEGRAL_TYPE_P (type)
1684                       && TREE_CODE (TREE_TYPE (val)) == COMPLEX_TYPE)
1685                     warn_for_assignment ("%s as integer rather than complex due to prototype", (char *) 0, name, parmnum + 1);
1686                   else if (TREE_CODE (type) == COMPLEX_TYPE
1687                            && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
1688                     warn_for_assignment ("%s as complex rather than floating due to prototype", (char *) 0, name, parmnum + 1);
1689                   else if (TREE_CODE (type) == REAL_TYPE
1690                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
1691                     warn_for_assignment ("%s as floating rather than integer due to prototype", (char *) 0, name, parmnum + 1);
1692                   else if (TREE_CODE (type) == COMPLEX_TYPE
1693                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
1694                     warn_for_assignment ("%s as complex rather than integer due to prototype", (char *) 0, name, parmnum + 1);
1695                   else if (TREE_CODE (type) == REAL_TYPE
1696                            && TREE_CODE (TREE_TYPE (val)) == COMPLEX_TYPE)
1697                     warn_for_assignment ("%s as floating rather than complex due to prototype", (char *) 0, name, parmnum + 1);
1698                   /* ??? At some point, messages should be written about
1699                      conversions between complex types, but that's too messy
1700                      to do now.  */
1701                   else if (TREE_CODE (type) == REAL_TYPE
1702                            && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
1703                     {
1704                       /* Warn if any argument is passed as `float',
1705                          since without a prototype it would be `double'.  */
1706                       if (formal_prec == TYPE_PRECISION (float_type_node))
1707                         warn_for_assignment ("%s as `float' rather than `double' due to prototype", (char *) 0, name, parmnum + 1);
1708                     }
1709                   /* Detect integer changing in width or signedness.
1710                      These warnings are only activated with
1711                      -Wconversion, not with -Wtraditional.  */
1712                   else if (warn_conversion && INTEGRAL_TYPE_P (type)
1713                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
1714                     {
1715                       tree would_have_been = default_conversion (val);
1716                       tree type1 = TREE_TYPE (would_have_been);
1717
1718                       if (TREE_CODE (type) == ENUMERAL_TYPE
1719                           && type == TREE_TYPE (val))
1720                         /* No warning if function asks for enum
1721                            and the actual arg is that enum type.  */
1722                         ;
1723                       else if (formal_prec != TYPE_PRECISION (type1))
1724                         warn_for_assignment ("%s with different width due to prototype", (char *) 0, name, parmnum + 1);
1725                       else if (TREE_UNSIGNED (type) == TREE_UNSIGNED (type1))
1726                         ;
1727                       /* Don't complain if the formal parameter type
1728                          is an enum, because we can't tell now whether
1729                          the value was an enum--even the same enum.  */
1730                       else if (TREE_CODE (type) == ENUMERAL_TYPE)
1731                         ;
1732                       else if (TREE_CODE (val) == INTEGER_CST
1733                                && int_fits_type_p (val, type))
1734                         /* Change in signedness doesn't matter
1735                            if a constant value is unaffected.  */
1736                         ;
1737                       /* Likewise for a constant in a NOP_EXPR.  */
1738                       else if (TREE_CODE (val) == NOP_EXPR
1739                                && TREE_CODE (TREE_OPERAND (val, 0)) == INTEGER_CST
1740                                && int_fits_type_p (TREE_OPERAND (val, 0), type))
1741                         ;
1742 #if 0 /* We never get such tree structure here.  */
1743                       else if (TREE_CODE (TREE_TYPE (val)) == ENUMERAL_TYPE
1744                                && int_fits_type_p (TYPE_MIN_VALUE (TREE_TYPE (val)), type)
1745                                && int_fits_type_p (TYPE_MAX_VALUE (TREE_TYPE (val)), type))
1746                         /* Change in signedness doesn't matter
1747                            if an enum value is unaffected.  */
1748                         ;
1749 #endif
1750                       /* If the value is extended from a narrower
1751                          unsigned type, it doesn't matter whether we
1752                          pass it as signed or unsigned; the value
1753                          certainly is the same either way.  */
1754                       else if (TYPE_PRECISION (TREE_TYPE (val)) < TYPE_PRECISION (type)
1755                                && TREE_UNSIGNED (TREE_TYPE (val)))
1756                         ;
1757                       else if (TREE_UNSIGNED (type))
1758                         warn_for_assignment ("%s as unsigned due to prototype", (char *) 0, name, parmnum + 1);
1759                       else
1760                         warn_for_assignment ("%s as signed due to prototype", (char *) 0, name, parmnum + 1);
1761                     }
1762                 }
1763
1764               parmval = convert_for_assignment (type, val,
1765                                                 (char *) 0, /* arg passing  */
1766                                                 fundecl, name, parmnum + 1);
1767
1768               if (PROMOTE_PROTOTYPES
1769                   && (TREE_CODE (type) == INTEGER_TYPE
1770                       || TREE_CODE (type) == ENUMERAL_TYPE
1771                       || TREE_CODE (type) == BOOLEAN_TYPE)
1772                   && (TYPE_PRECISION (type) < TYPE_PRECISION (integer_type_node)))
1773                 parmval = default_conversion (parmval);
1774             }
1775           result = tree_cons (NULL_TREE, parmval, result);
1776         }
1777       else if (TREE_CODE (TREE_TYPE (val)) == REAL_TYPE
1778                && (TYPE_PRECISION (TREE_TYPE (val))
1779                    < TYPE_PRECISION (double_type_node)))
1780         /* Convert `float' to `double'.  */
1781         result = tree_cons (NULL_TREE, convert (double_type_node, val), result);
1782       else
1783         /* Convert `short' and `char' to full-size `int'.  */
1784         result = tree_cons (NULL_TREE, default_conversion (val), result);
1785
1786       if (typetail)
1787         typetail = TREE_CHAIN (typetail);
1788     }
1789
1790   if (typetail != 0 && TREE_VALUE (typetail) != void_type_node)
1791     {
1792       if (name)
1793         error ("too few arguments to function `%s'",
1794                IDENTIFIER_POINTER (name));
1795       else
1796         error ("too few arguments to function");
1797     }
1798
1799   return nreverse (result);
1800 }
1801 \f
1802 /* This is the entry point used by the parser
1803    for binary operators in the input.
1804    In addition to constructing the expression,
1805    we check for operands that were written with other binary operators
1806    in a way that is likely to confuse the user.  */
1807
1808 tree
1809 parser_build_binary_op (code, arg1, arg2)
1810      enum tree_code code;
1811      tree arg1, arg2;
1812 {
1813   tree result = build_binary_op (code, arg1, arg2, 1);
1814
1815   char class;
1816   char class1 = TREE_CODE_CLASS (TREE_CODE (arg1));
1817   char class2 = TREE_CODE_CLASS (TREE_CODE (arg2));
1818   enum tree_code code1 = ERROR_MARK;
1819   enum tree_code code2 = ERROR_MARK;
1820
1821   if (class1 == 'e' || class1 == '1'
1822       || class1 == '2' || class1 == '<')
1823     code1 = C_EXP_ORIGINAL_CODE (arg1);
1824   if (class2 == 'e' || class2 == '1'
1825       || class2 == '2' || class2 == '<')
1826     code2 = C_EXP_ORIGINAL_CODE (arg2);
1827
1828   /* Check for cases such as x+y<<z which users are likely
1829      to misinterpret.  If parens are used, C_EXP_ORIGINAL_CODE
1830      is cleared to prevent these warnings.  */
1831   if (warn_parentheses)
1832     {
1833       if (code == LSHIFT_EXPR || code == RSHIFT_EXPR)
1834         {
1835           if (code1 == PLUS_EXPR || code1 == MINUS_EXPR
1836               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
1837             warning ("suggest parentheses around + or - inside shift");
1838         }
1839
1840       if (code == TRUTH_ORIF_EXPR)
1841         {
1842           if (code1 == TRUTH_ANDIF_EXPR
1843               || code2 == TRUTH_ANDIF_EXPR)
1844             warning ("suggest parentheses around && within ||");
1845         }
1846
1847       if (code == BIT_IOR_EXPR)
1848         {
1849           if (code1 == BIT_AND_EXPR || code1 == BIT_XOR_EXPR
1850               || code1 == PLUS_EXPR || code1 == MINUS_EXPR
1851               || code2 == BIT_AND_EXPR || code2 == BIT_XOR_EXPR
1852               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
1853             warning ("suggest parentheses around arithmetic in operand of |");
1854           /* Check cases like x|y==z */
1855           if (TREE_CODE_CLASS (code1) == '<' || TREE_CODE_CLASS (code2) == '<')
1856             warning ("suggest parentheses around comparison in operand of |");
1857         }
1858
1859       if (code == BIT_XOR_EXPR)
1860         {
1861           if (code1 == BIT_AND_EXPR
1862               || code1 == PLUS_EXPR || code1 == MINUS_EXPR
1863               || code2 == BIT_AND_EXPR
1864               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
1865             warning ("suggest parentheses around arithmetic in operand of ^");
1866           /* Check cases like x^y==z */
1867           if (TREE_CODE_CLASS (code1) == '<' || TREE_CODE_CLASS (code2) == '<')
1868             warning ("suggest parentheses around comparison in operand of ^");
1869         }
1870
1871       if (code == BIT_AND_EXPR)
1872         {
1873           if (code1 == PLUS_EXPR || code1 == MINUS_EXPR
1874               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
1875             warning ("suggest parentheses around + or - in operand of &");
1876           /* Check cases like x&y==z */
1877           if (TREE_CODE_CLASS (code1) == '<' || TREE_CODE_CLASS (code2) == '<')
1878             warning ("suggest parentheses around comparison in operand of &");
1879         }
1880     }
1881
1882   /* Similarly, check for cases like 1<=i<=10 that are probably errors.  */
1883   if (TREE_CODE_CLASS (code) == '<' && extra_warnings
1884       && (TREE_CODE_CLASS (code1) == '<' || TREE_CODE_CLASS (code2) == '<'))
1885     warning ("comparisons like X<=Y<=Z do not have their mathematical meaning");
1886
1887   unsigned_conversion_warning (result, arg1);
1888   unsigned_conversion_warning (result, arg2);
1889   overflow_warning (result);
1890
1891   class = TREE_CODE_CLASS (TREE_CODE (result));
1892
1893   /* Record the code that was specified in the source,
1894      for the sake of warnings about confusing nesting.  */
1895   if (class == 'e' || class == '1'
1896       || class == '2' || class == '<')
1897     C_SET_EXP_ORIGINAL_CODE (result, code);
1898   else
1899     {
1900       int flag = TREE_CONSTANT (result);
1901       /* We used to use NOP_EXPR rather than NON_LVALUE_EXPR
1902          so that convert_for_assignment wouldn't strip it.
1903          That way, we got warnings for things like p = (1 - 1).
1904          But it turns out we should not get those warnings.  */
1905       result = build1 (NON_LVALUE_EXPR, TREE_TYPE (result), result);
1906       C_SET_EXP_ORIGINAL_CODE (result, code);
1907       TREE_CONSTANT (result) = flag;
1908     }
1909
1910   return result;
1911 }
1912
1913 /* Build a binary-operation expression without default conversions.
1914    CODE is the kind of expression to build.
1915    This function differs from `build' in several ways:
1916    the data type of the result is computed and recorded in it,
1917    warnings are generated if arg data types are invalid,
1918    special handling for addition and subtraction of pointers is known,
1919    and some optimization is done (operations on narrow ints
1920    are done in the narrower type when that gives the same result).
1921    Constant folding is also done before the result is returned.
1922
1923    Note that the operands will never have enumeral types, or function
1924    or array types, because either they will have the default conversions
1925    performed or they have both just been converted to some other type in which
1926    the arithmetic is to be done.  */
1927
1928 tree
1929 build_binary_op (code, orig_op0, orig_op1, convert_p)
1930      enum tree_code code;
1931      tree orig_op0, orig_op1;
1932      int convert_p;
1933 {
1934   tree type0, type1;
1935   register enum tree_code code0, code1;
1936   tree op0, op1;
1937
1938   /* Expression code to give to the expression when it is built.
1939      Normally this is CODE, which is what the caller asked for,
1940      but in some special cases we change it.  */
1941   register enum tree_code resultcode = code;
1942
1943   /* Data type in which the computation is to be performed.
1944      In the simplest cases this is the common type of the arguments.  */
1945   register tree result_type = NULL;
1946
1947   /* Nonzero means operands have already been type-converted
1948      in whatever way is necessary.
1949      Zero means they need to be converted to RESULT_TYPE.  */
1950   int converted = 0;
1951
1952   /* Nonzero means create the expression with this type, rather than
1953      RESULT_TYPE.  */
1954   tree build_type = 0;
1955
1956   /* Nonzero means after finally constructing the expression
1957      convert it to this type.  */
1958   tree final_type = 0;
1959
1960   /* Nonzero if this is an operation like MIN or MAX which can
1961      safely be computed in short if both args are promoted shorts.
1962      Also implies COMMON.
1963      -1 indicates a bitwise operation; this makes a difference
1964      in the exact conditions for when it is safe to do the operation
1965      in a narrower mode.  */
1966   int shorten = 0;
1967
1968   /* Nonzero if this is a comparison operation;
1969      if both args are promoted shorts, compare the original shorts.
1970      Also implies COMMON.  */
1971   int short_compare = 0;
1972
1973   /* Nonzero if this is a right-shift operation, which can be computed on the
1974      original short and then promoted if the operand is a promoted short.  */
1975   int short_shift = 0;
1976
1977   /* Nonzero means set RESULT_TYPE to the common type of the args.  */
1978   int common = 0;
1979
1980   if (convert_p)
1981     {
1982       op0 = default_conversion (orig_op0);
1983       op1 = default_conversion (orig_op1);
1984     }
1985   else
1986     {
1987       op0 = orig_op0;
1988       op1 = orig_op1;
1989     }
1990
1991   type0 = TREE_TYPE (op0);
1992   type1 = TREE_TYPE (op1);
1993
1994   /* The expression codes of the data types of the arguments tell us
1995      whether the arguments are integers, floating, pointers, etc.  */
1996   code0 = TREE_CODE (type0);
1997   code1 = TREE_CODE (type1);
1998
1999   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
2000   STRIP_TYPE_NOPS (op0);
2001   STRIP_TYPE_NOPS (op1);
2002
2003   /* If an error was already reported for one of the arguments,
2004      avoid reporting another error.  */
2005
2006   if (code0 == ERROR_MARK || code1 == ERROR_MARK)
2007     return error_mark_node;
2008
2009   switch (code)
2010     {
2011     case PLUS_EXPR:
2012       /* Handle the pointer + int case.  */
2013       if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
2014         return pointer_int_sum (PLUS_EXPR, op0, op1);
2015       else if (code1 == POINTER_TYPE && code0 == INTEGER_TYPE)
2016         return pointer_int_sum (PLUS_EXPR, op1, op0);
2017       else
2018         common = 1;
2019       break;
2020
2021     case MINUS_EXPR:
2022       /* Subtraction of two similar pointers.
2023          We must subtract them as integers, then divide by object size.  */
2024       if (code0 == POINTER_TYPE && code1 == POINTER_TYPE
2025           && comp_target_types (type0, type1))
2026         return pointer_diff (op0, op1);
2027       /* Handle pointer minus int.  Just like pointer plus int.  */
2028       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
2029         return pointer_int_sum (MINUS_EXPR, op0, op1);
2030       else
2031         common = 1;
2032       break;
2033
2034     case MULT_EXPR:
2035       common = 1;
2036       break;
2037
2038     case TRUNC_DIV_EXPR:
2039     case CEIL_DIV_EXPR:
2040     case FLOOR_DIV_EXPR:
2041     case ROUND_DIV_EXPR:
2042     case EXACT_DIV_EXPR:
2043       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
2044            || code0 == COMPLEX_TYPE)
2045           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
2046               || code1 == COMPLEX_TYPE))
2047         {
2048           if (!(code0 == INTEGER_TYPE && code1 == INTEGER_TYPE))
2049             resultcode = RDIV_EXPR;
2050           else
2051             /* Although it would be tempting to shorten always here, that
2052                loses on some targets, since the modulo instruction is
2053                undefined if the quotient can't be represented in the
2054                computation mode.  We shorten only if unsigned or if
2055                dividing by something we know != -1.  */
2056             shorten = (TREE_UNSIGNED (TREE_TYPE (orig_op0))
2057                        || (TREE_CODE (op1) == INTEGER_CST
2058                            && ! integer_all_onesp (op1)));
2059           common = 1;
2060         }
2061       break;
2062
2063     case BIT_AND_EXPR:
2064     case BIT_ANDTC_EXPR:
2065     case BIT_IOR_EXPR:
2066     case BIT_XOR_EXPR:
2067       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2068         shorten = -1;
2069       /* If one operand is a constant, and the other is a short type
2070          that has been converted to an int,
2071          really do the work in the short type and then convert the
2072          result to int.  If we are lucky, the constant will be 0 or 1
2073          in the short type, making the entire operation go away.  */
2074       if (TREE_CODE (op0) == INTEGER_CST
2075           && TREE_CODE (op1) == NOP_EXPR
2076           && TYPE_PRECISION (type1) > TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (op1, 0)))
2077           && TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op1, 0))))
2078         {
2079           final_type = result_type;
2080           op1 = TREE_OPERAND (op1, 0);
2081           result_type = TREE_TYPE (op1);
2082         }
2083       if (TREE_CODE (op1) == INTEGER_CST
2084           && TREE_CODE (op0) == NOP_EXPR
2085           && TYPE_PRECISION (type0) > TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (op0, 0)))
2086           && TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op0, 0))))
2087         {
2088           final_type = result_type;
2089           op0 = TREE_OPERAND (op0, 0);
2090           result_type = TREE_TYPE (op0);
2091         }
2092       break;
2093
2094     case TRUNC_MOD_EXPR:
2095     case FLOOR_MOD_EXPR:
2096       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2097         {
2098           /* Although it would be tempting to shorten always here, that loses
2099              on some targets, since the modulo instruction is undefined if the
2100              quotient can't be represented in the computation mode.  We shorten
2101              only if unsigned or if dividing by something we know != -1.  */
2102           shorten = (TREE_UNSIGNED (TREE_TYPE (orig_op0))
2103                      || (TREE_CODE (op1) == INTEGER_CST
2104                          && ! integer_all_onesp (op1)));
2105           common = 1;
2106         }
2107       break;
2108
2109     case TRUTH_ANDIF_EXPR:
2110     case TRUTH_ORIF_EXPR:
2111     case TRUTH_AND_EXPR:
2112     case TRUTH_OR_EXPR:
2113     case TRUTH_XOR_EXPR:
2114       if ((code0 == INTEGER_TYPE || code0 == POINTER_TYPE
2115            || code0 == REAL_TYPE || code0 == COMPLEX_TYPE)
2116           && (code1 == INTEGER_TYPE || code1 == POINTER_TYPE
2117               || code1 == REAL_TYPE || code1 == COMPLEX_TYPE))
2118         {
2119           /* Result of these operations is always an int,
2120              but that does not mean the operands should be
2121              converted to ints!  */
2122           result_type = integer_type_node;
2123           op0 = truthvalue_conversion (op0);
2124           op1 = truthvalue_conversion (op1);
2125           converted = 1;
2126         }
2127       break;
2128
2129       /* Shift operations: result has same type as first operand;
2130          always convert second operand to int.
2131          Also set SHORT_SHIFT if shifting rightward.  */
2132
2133     case RSHIFT_EXPR:
2134       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2135         {
2136           if (TREE_CODE (op1) == INTEGER_CST && skip_evaluation == 0)
2137             {
2138               if (tree_int_cst_sgn (op1) < 0)
2139                 warning ("right shift count is negative");
2140               else
2141                 {
2142                   if (! integer_zerop (op1))
2143                     short_shift = 1;
2144
2145                   if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
2146                     warning ("right shift count >= width of type");
2147                 }
2148             }
2149
2150           /* Use the type of the value to be shifted.
2151              This is what most traditional C compilers do.  */
2152           result_type = type0;
2153           /* Unless traditional, convert the shift-count to an integer,
2154              regardless of size of value being shifted.  */
2155           if (! flag_traditional)
2156             {
2157               if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
2158                 op1 = convert (integer_type_node, op1);
2159               /* Avoid converting op1 to result_type later.  */
2160               converted = 1;
2161             }
2162         }
2163       break;
2164
2165     case LSHIFT_EXPR:
2166       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2167         {
2168           if (TREE_CODE (op1) == INTEGER_CST && skip_evaluation == 0)
2169             {
2170               if (tree_int_cst_sgn (op1) < 0)
2171                 warning ("left shift count is negative");
2172
2173               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
2174                 warning ("left shift count >= width of type");
2175             }
2176
2177           /* Use the type of the value to be shifted.
2178              This is what most traditional C compilers do.  */
2179           result_type = type0;
2180           /* Unless traditional, convert the shift-count to an integer,
2181              regardless of size of value being shifted.  */
2182           if (! flag_traditional)
2183             {
2184               if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
2185                 op1 = convert (integer_type_node, op1);
2186               /* Avoid converting op1 to result_type later.  */
2187               converted = 1;
2188             }
2189         }
2190       break;
2191
2192     case RROTATE_EXPR:
2193     case LROTATE_EXPR:
2194       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
2195         {
2196           if (TREE_CODE (op1) == INTEGER_CST && skip_evaluation == 0)
2197             {
2198               if (tree_int_cst_sgn (op1) < 0)
2199                 warning ("shift count is negative");
2200               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
2201                 warning ("shift count >= width of type");
2202             }
2203
2204           /* Use the type of the value to be shifted.
2205              This is what most traditional C compilers do.  */
2206           result_type = type0;
2207           /* Unless traditional, convert the shift-count to an integer,
2208              regardless of size of value being shifted.  */
2209           if (! flag_traditional)
2210             {
2211               if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
2212                 op1 = convert (integer_type_node, op1);
2213               /* Avoid converting op1 to result_type later.  */
2214               converted = 1;
2215             }
2216         }
2217       break;
2218
2219     case EQ_EXPR:
2220     case NE_EXPR:
2221       if (warn_float_equal && (code0 == REAL_TYPE || code1 == REAL_TYPE))
2222         warning ("comparing floating point with == or != is unsafe");
2223       /* Result of comparison is always int,
2224          but don't convert the args to int!  */
2225       build_type = integer_type_node;
2226       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
2227            || code0 == COMPLEX_TYPE)
2228           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
2229               || code1 == COMPLEX_TYPE))
2230         short_compare = 1;
2231       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
2232         {
2233           register tree tt0 = TREE_TYPE (type0);
2234           register tree tt1 = TREE_TYPE (type1);
2235           /* Anything compares with void *.  void * compares with anything.
2236              Otherwise, the targets must be compatible
2237              and both must be object or both incomplete.  */
2238           if (comp_target_types (type0, type1))
2239             result_type = common_type (type0, type1);
2240           else if (VOID_TYPE_P (tt0))
2241             {
2242               /* op0 != orig_op0 detects the case of something
2243                  whose value is 0 but which isn't a valid null ptr const.  */
2244               if (pedantic && (!integer_zerop (op0) || op0 != orig_op0)
2245                   && TREE_CODE (tt1) == FUNCTION_TYPE)
2246                 pedwarn ("ISO C forbids comparison of `void *' with function pointer");
2247             }
2248           else if (VOID_TYPE_P (tt1))
2249             {
2250               if (pedantic && (!integer_zerop (op1) || op1 != orig_op1)
2251                   && TREE_CODE (tt0) == FUNCTION_TYPE)
2252                 pedwarn ("ISO C forbids comparison of `void *' with function pointer");
2253             }
2254           else
2255             pedwarn ("comparison of distinct pointer types lacks a cast");
2256
2257           if (result_type == NULL_TREE)
2258             result_type = ptr_type_node;
2259         }
2260       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
2261                && integer_zerop (op1))
2262         result_type = type0;
2263       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
2264                && integer_zerop (op0))
2265         result_type = type1;
2266       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
2267         {
2268           result_type = type0;
2269           if (! flag_traditional)
2270             pedwarn ("comparison between pointer and integer");
2271         }
2272       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
2273         {
2274           result_type = type1;
2275           if (! flag_traditional)
2276             pedwarn ("comparison between pointer and integer");
2277         }
2278       break;
2279
2280     case MAX_EXPR:
2281     case MIN_EXPR:
2282       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
2283           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
2284         shorten = 1;
2285       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
2286         {
2287           if (comp_target_types (type0, type1))
2288             {
2289               result_type = common_type (type0, type1);
2290               if (pedantic
2291                   && TREE_CODE (TREE_TYPE (type0)) == FUNCTION_TYPE)
2292                 pedwarn ("ISO C forbids ordered comparisons of pointers to functions");
2293             }
2294           else
2295             {
2296               result_type = ptr_type_node;
2297               pedwarn ("comparison of distinct pointer types lacks a cast");
2298             }
2299         }
2300       break;
2301
2302     case LE_EXPR:
2303     case GE_EXPR:
2304     case LT_EXPR:
2305     case GT_EXPR:
2306       build_type = integer_type_node;
2307       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
2308           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
2309         short_compare = 1;
2310       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
2311         {
2312           if (comp_target_types (type0, type1))
2313             {
2314               result_type = common_type (type0, type1);
2315               if (!COMPLETE_TYPE_P (TREE_TYPE (type0))
2316                   != !COMPLETE_TYPE_P (TREE_TYPE (type1)))
2317                 pedwarn ("comparison of complete and incomplete pointers");
2318               else if (pedantic
2319                        && TREE_CODE (TREE_TYPE (type0)) == FUNCTION_TYPE)
2320                 pedwarn ("ISO C forbids ordered comparisons of pointers to functions");
2321             }
2322           else
2323             {
2324               result_type = ptr_type_node;
2325               pedwarn ("comparison of distinct pointer types lacks a cast");
2326             }
2327         }
2328       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
2329                && integer_zerop (op1))
2330         {
2331           result_type = type0;
2332           if (pedantic || extra_warnings)
2333             pedwarn ("ordered comparison of pointer with integer zero");
2334         }
2335       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
2336                && integer_zerop (op0))
2337         {
2338           result_type = type1;
2339           if (pedantic)
2340             pedwarn ("ordered comparison of pointer with integer zero");
2341         }
2342       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
2343         {
2344           result_type = type0;
2345           if (! flag_traditional)
2346             pedwarn ("comparison between pointer and integer");
2347         }
2348       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
2349         {
2350           result_type = type1;
2351           if (! flag_traditional)
2352             pedwarn ("comparison between pointer and integer");
2353         }
2354       break;
2355
2356     case UNORDERED_EXPR:
2357     case ORDERED_EXPR:
2358     case UNLT_EXPR:
2359     case UNLE_EXPR:
2360     case UNGT_EXPR:
2361     case UNGE_EXPR:
2362     case UNEQ_EXPR:
2363       build_type = integer_type_node;
2364       if (code0 != REAL_TYPE || code1 != REAL_TYPE)
2365         {
2366           error ("unordered comparison on non-floating point argument");
2367           return error_mark_node;
2368         }
2369       common = 1;
2370       break;
2371
2372     default:
2373       break;
2374     }
2375
2376   if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE || code0 == COMPLEX_TYPE)
2377       &&
2378       (code1 == INTEGER_TYPE || code1 == REAL_TYPE || code1 == COMPLEX_TYPE))
2379     {
2380       int none_complex = (code0 != COMPLEX_TYPE && code1 != COMPLEX_TYPE);
2381
2382       if (shorten || common || short_compare)
2383         result_type = common_type (type0, type1);
2384
2385       /* For certain operations (which identify themselves by shorten != 0)
2386          if both args were extended from the same smaller type,
2387          do the arithmetic in that type and then extend.
2388
2389          shorten !=0 and !=1 indicates a bitwise operation.
2390          For them, this optimization is safe only if
2391          both args are zero-extended or both are sign-extended.
2392          Otherwise, we might change the result.
2393          Eg, (short)-1 | (unsigned short)-1 is (int)-1
2394          but calculated in (unsigned short) it would be (unsigned short)-1.  */
2395
2396       if (shorten && none_complex)
2397         {
2398           int unsigned0, unsigned1;
2399           tree arg0 = get_narrower (op0, &unsigned0);
2400           tree arg1 = get_narrower (op1, &unsigned1);
2401           /* UNS is 1 if the operation to be done is an unsigned one.  */
2402           int uns = TREE_UNSIGNED (result_type);
2403           tree type;
2404
2405           final_type = result_type;
2406
2407           /* Handle the case that OP0 (or OP1) does not *contain* a conversion
2408              but it *requires* conversion to FINAL_TYPE.  */
2409
2410           if ((TYPE_PRECISION (TREE_TYPE (op0))
2411                == TYPE_PRECISION (TREE_TYPE (arg0)))
2412               && TREE_TYPE (op0) != final_type)
2413             unsigned0 = TREE_UNSIGNED (TREE_TYPE (op0));
2414           if ((TYPE_PRECISION (TREE_TYPE (op1))
2415                == TYPE_PRECISION (TREE_TYPE (arg1)))
2416               && TREE_TYPE (op1) != final_type)
2417             unsigned1 = TREE_UNSIGNED (TREE_TYPE (op1));
2418
2419           /* Now UNSIGNED0 is 1 if ARG0 zero-extends to FINAL_TYPE.  */
2420
2421           /* For bitwise operations, signedness of nominal type
2422              does not matter.  Consider only how operands were extended.  */
2423           if (shorten == -1)
2424             uns = unsigned0;
2425
2426           /* Note that in all three cases below we refrain from optimizing
2427              an unsigned operation on sign-extended args.
2428              That would not be valid.  */
2429
2430           /* Both args variable: if both extended in same way
2431              from same width, do it in that width.
2432              Do it unsigned if args were zero-extended.  */
2433           if ((TYPE_PRECISION (TREE_TYPE (arg0))
2434                < TYPE_PRECISION (result_type))
2435               && (TYPE_PRECISION (TREE_TYPE (arg1))
2436                   == TYPE_PRECISION (TREE_TYPE (arg0)))
2437               && unsigned0 == unsigned1
2438               && (unsigned0 || !uns))
2439             result_type
2440               = signed_or_unsigned_type (unsigned0,
2441                                          common_type (TREE_TYPE (arg0), TREE_TYPE (arg1)));
2442           else if (TREE_CODE (arg0) == INTEGER_CST
2443                    && (unsigned1 || !uns)
2444                    && (TYPE_PRECISION (TREE_TYPE (arg1))
2445                        < TYPE_PRECISION (result_type))
2446                    && (type = signed_or_unsigned_type (unsigned1,
2447                                                        TREE_TYPE (arg1)),
2448                        int_fits_type_p (arg0, type)))
2449             result_type = type;
2450           else if (TREE_CODE (arg1) == INTEGER_CST
2451                    && (unsigned0 || !uns)
2452                    && (TYPE_PRECISION (TREE_TYPE (arg0))
2453                        < TYPE_PRECISION (result_type))
2454                    && (type = signed_or_unsigned_type (unsigned0,
2455                                                        TREE_TYPE (arg0)),
2456                        int_fits_type_p (arg1, type)))
2457             result_type = type;
2458         }
2459
2460       /* Shifts can be shortened if shifting right.  */
2461
2462       if (short_shift)
2463         {
2464           int unsigned_arg;
2465           tree arg0 = get_narrower (op0, &unsigned_arg);
2466
2467           final_type = result_type;
2468
2469           if (arg0 == op0 && final_type == TREE_TYPE (op0))
2470             unsigned_arg = TREE_UNSIGNED (TREE_TYPE (op0));
2471
2472           if (TYPE_PRECISION (TREE_TYPE (arg0)) < TYPE_PRECISION (result_type)
2473               /* We can shorten only if the shift count is less than the
2474                  number of bits in the smaller type size.  */
2475               && compare_tree_int (op1, TYPE_PRECISION (TREE_TYPE (arg0))) < 0
2476               /* If arg is sign-extended and then unsigned-shifted,
2477                  we can simulate this with a signed shift in arg's type
2478                  only if the extended result is at least twice as wide
2479                  as the arg.  Otherwise, the shift could use up all the
2480                  ones made by sign-extension and bring in zeros.
2481                  We can't optimize that case at all, but in most machines
2482                  it never happens because available widths are 2**N.  */
2483               && (!TREE_UNSIGNED (final_type)
2484                   || unsigned_arg
2485                   || (2 * TYPE_PRECISION (TREE_TYPE (arg0))
2486                       <= TYPE_PRECISION (result_type))))
2487             {
2488               /* Do an unsigned shift if the operand was zero-extended.  */
2489               result_type
2490                 = signed_or_unsigned_type (unsigned_arg,
2491                                            TREE_TYPE (arg0));
2492               /* Convert value-to-be-shifted to that type.  */
2493               if (TREE_TYPE (op0) != result_type)
2494                 op0 = convert (result_type, op0);
2495               converted = 1;
2496             }
2497         }
2498
2499       /* Comparison operations are shortened too but differently.
2500          They identify themselves by setting short_compare = 1.  */
2501
2502       if (short_compare)
2503         {
2504           /* Don't write &op0, etc., because that would prevent op0
2505              from being kept in a register.
2506              Instead, make copies of the our local variables and
2507              pass the copies by reference, then copy them back afterward.  */
2508           tree xop0 = op0, xop1 = op1, xresult_type = result_type;
2509           enum tree_code xresultcode = resultcode;
2510           tree val
2511             = shorten_compare (&xop0, &xop1, &xresult_type, &xresultcode);
2512
2513           if (val != 0)
2514             return val;
2515
2516           op0 = xop0, op1 = xop1;
2517           converted = 1;
2518           resultcode = xresultcode;
2519
2520           if ((warn_sign_compare < 0 ? extra_warnings : warn_sign_compare != 0)
2521               && skip_evaluation == 0)
2522             {
2523               int op0_signed = ! TREE_UNSIGNED (TREE_TYPE (orig_op0));
2524               int op1_signed = ! TREE_UNSIGNED (TREE_TYPE (orig_op1));
2525               int unsignedp0, unsignedp1;
2526               tree primop0 = get_narrower (op0, &unsignedp0);
2527               tree primop1 = get_narrower (op1, &unsignedp1);
2528
2529               xop0 = orig_op0;
2530               xop1 = orig_op1;
2531               STRIP_TYPE_NOPS (xop0);
2532               STRIP_TYPE_NOPS (xop1);
2533
2534               /* Give warnings for comparisons between signed and unsigned
2535                  quantities that may fail.
2536
2537                  Do the checking based on the original operand trees, so that
2538                  casts will be considered, but default promotions won't be.
2539
2540                  Do not warn if the comparison is being done in a signed type,
2541                  since the signed type will only be chosen if it can represent
2542                  all the values of the unsigned type.  */
2543               if (! TREE_UNSIGNED (result_type))
2544                 /* OK */;
2545               /* Do not warn if both operands are the same signedness.  */
2546               else if (op0_signed == op1_signed)
2547                 /* OK */;
2548               else
2549                 {
2550                   tree sop, uop;
2551
2552                   if (op0_signed)
2553                     sop = xop0, uop = xop1;
2554                   else
2555                     sop = xop1, uop = xop0;
2556
2557                   /* Do not warn if the signed quantity is an
2558                      unsuffixed integer literal (or some static
2559                      constant expression involving such literals or a
2560                      conditional expression involving such literals)
2561                      and it is non-negative.  */
2562                   if (tree_expr_nonnegative_p (sop))
2563                     /* OK */;
2564                   /* Do not warn if the comparison is an equality operation,
2565                      the unsigned quantity is an integral constant, and it
2566                      would fit in the result if the result were signed.  */
2567                   else if (TREE_CODE (uop) == INTEGER_CST
2568                            && (resultcode == EQ_EXPR || resultcode == NE_EXPR)
2569                            && int_fits_type_p (uop, signed_type (result_type)))
2570                     /* OK */;
2571                   /* Do not warn if the unsigned quantity is an enumeration
2572                      constant and its maximum value would fit in the result
2573                      if the result were signed.  */
2574                   else if (TREE_CODE (uop) == INTEGER_CST
2575                            && TREE_CODE (TREE_TYPE (uop)) == ENUMERAL_TYPE
2576                            && int_fits_type_p (TYPE_MAX_VALUE (TREE_TYPE(uop)),
2577                                                signed_type (result_type)))
2578                     /* OK */;
2579                   else
2580                     warning ("comparison between signed and unsigned");
2581                 }
2582
2583               /* Warn if two unsigned values are being compared in a size
2584                  larger than their original size, and one (and only one) is the
2585                  result of a `~' operator.  This comparison will always fail.
2586
2587                  Also warn if one operand is a constant, and the constant
2588                  does not have all bits set that are set in the ~ operand
2589                  when it is extended.  */
2590
2591               if ((TREE_CODE (primop0) == BIT_NOT_EXPR)
2592                   != (TREE_CODE (primop1) == BIT_NOT_EXPR))
2593                 {
2594                   if (TREE_CODE (primop0) == BIT_NOT_EXPR)
2595                     primop0 = get_narrower (TREE_OPERAND (primop0, 0),
2596                                             &unsignedp0);
2597                   else
2598                     primop1 = get_narrower (TREE_OPERAND (primop1, 0),
2599                                             &unsignedp1);
2600
2601                   if (host_integerp (primop0, 0) || host_integerp (primop1, 0))
2602                     {
2603                       tree primop;
2604                       HOST_WIDE_INT constant, mask;
2605                       int unsignedp, bits;
2606
2607                       if (host_integerp (primop0, 0))
2608                         {
2609                           primop = primop1;
2610                           unsignedp = unsignedp1;
2611                           constant = tree_low_cst (primop0, 0);
2612                         }
2613                       else
2614                         {
2615                           primop = primop0;
2616                           unsignedp = unsignedp0;
2617                           constant = tree_low_cst (primop1, 0);
2618                         }
2619
2620                       bits = TYPE_PRECISION (TREE_TYPE (primop));
2621                       if (bits < TYPE_PRECISION (result_type)
2622                           && bits < HOST_BITS_PER_WIDE_INT && unsignedp)
2623                         {
2624                           mask = (~ (HOST_WIDE_INT) 0) << bits;
2625                           if ((mask & constant) != mask)
2626                             warning ("comparison of promoted ~unsigned with constant");
2627                         }
2628                     }
2629                   else if (unsignedp0 && unsignedp1
2630                            && (TYPE_PRECISION (TREE_TYPE (primop0))
2631                                < TYPE_PRECISION (result_type))
2632                            && (TYPE_PRECISION (TREE_TYPE (primop1))
2633                                < TYPE_PRECISION (result_type)))
2634                     warning ("comparison of promoted ~unsigned with unsigned");
2635                 }
2636             }
2637         }
2638     }
2639
2640   /* At this point, RESULT_TYPE must be nonzero to avoid an error message.
2641      If CONVERTED is zero, both args will be converted to type RESULT_TYPE.
2642      Then the expression will be built.
2643      It will be given type FINAL_TYPE if that is nonzero;
2644      otherwise, it will be given type RESULT_TYPE.  */
2645
2646   if (!result_type)
2647     {
2648       binary_op_error (code);
2649       return error_mark_node;
2650     }
2651
2652   if (! converted)
2653     {
2654       if (TREE_TYPE (op0) != result_type)
2655         op0 = convert (result_type, op0);
2656       if (TREE_TYPE (op1) != result_type)
2657         op1 = convert (result_type, op1);
2658     }
2659
2660   if (build_type == NULL_TREE)
2661     build_type = result_type;
2662
2663   {
2664     register tree result = build (resultcode, build_type, op0, op1);
2665     register tree folded;
2666
2667     folded = fold (result);
2668     if (folded == result)
2669       TREE_CONSTANT (folded) = TREE_CONSTANT (op0) & TREE_CONSTANT (op1);
2670     if (final_type != 0)
2671       return convert (final_type, folded);
2672     return folded;
2673   }
2674 }
2675 \f
2676 /* Return a tree for the sum or difference (RESULTCODE says which)
2677    of pointer PTROP and integer INTOP.  */
2678
2679 static tree
2680 pointer_int_sum (resultcode, ptrop, intop)
2681      enum tree_code resultcode;
2682      register tree ptrop, intop;
2683 {
2684   tree size_exp;
2685
2686   register tree result;
2687   register tree folded;
2688
2689   /* The result is a pointer of the same type that is being added.  */
2690
2691   register tree result_type = TREE_TYPE (ptrop);
2692
2693   if (TREE_CODE (TREE_TYPE (result_type)) == VOID_TYPE)
2694     {
2695       if (pedantic || warn_pointer_arith)
2696         pedwarn ("pointer of type `void *' used in arithmetic");
2697       size_exp = integer_one_node;
2698     }
2699   else if (TREE_CODE (TREE_TYPE (result_type)) == FUNCTION_TYPE)
2700     {
2701       if (pedantic || warn_pointer_arith)
2702         pedwarn ("pointer to a function used in arithmetic");
2703       size_exp = integer_one_node;
2704     }
2705   else
2706     size_exp = c_size_in_bytes (TREE_TYPE (result_type));
2707
2708   /* If what we are about to multiply by the size of the elements
2709      contains a constant term, apply distributive law
2710      and multiply that constant term separately.
2711      This helps produce common subexpressions.  */
2712
2713   if ((TREE_CODE (intop) == PLUS_EXPR || TREE_CODE (intop) == MINUS_EXPR)
2714       && ! TREE_CONSTANT (intop)
2715       && TREE_CONSTANT (TREE_OPERAND (intop, 1))
2716       && TREE_CONSTANT (size_exp)
2717       /* If the constant comes from pointer subtraction,
2718          skip this optimization--it would cause an error.  */
2719       && TREE_CODE (TREE_TYPE (TREE_OPERAND (intop, 0))) == INTEGER_TYPE
2720       /* If the constant is unsigned, and smaller than the pointer size,
2721          then we must skip this optimization.  This is because it could cause
2722          an overflow error if the constant is negative but INTOP is not.  */
2723       && (! TREE_UNSIGNED (TREE_TYPE (intop))
2724           || (TYPE_PRECISION (TREE_TYPE (intop))
2725               == TYPE_PRECISION (TREE_TYPE (ptrop)))))
2726     {
2727       enum tree_code subcode = resultcode;
2728       tree int_type = TREE_TYPE (intop);
2729       if (TREE_CODE (intop) == MINUS_EXPR)
2730         subcode = (subcode == PLUS_EXPR ? MINUS_EXPR : PLUS_EXPR);
2731       /* Convert both subexpression types to the type of intop,
2732          because weird cases involving pointer arithmetic
2733          can result in a sum or difference with different type args.  */
2734       ptrop = build_binary_op (subcode, ptrop,
2735                                convert (int_type, TREE_OPERAND (intop, 1)), 1);
2736       intop = convert (int_type, TREE_OPERAND (intop, 0));
2737     }
2738
2739   /* Convert the integer argument to a type the same size as sizetype
2740      so the multiply won't overflow spuriously.  */
2741
2742   if (TYPE_PRECISION (TREE_TYPE (intop)) != TYPE_PRECISION (sizetype)
2743       || TREE_UNSIGNED (TREE_TYPE (intop)) != TREE_UNSIGNED (sizetype))
2744     intop = convert (type_for_size (TYPE_PRECISION (sizetype),
2745                                     TREE_UNSIGNED (sizetype)), intop);
2746
2747   /* Replace the integer argument with a suitable product by the object size.
2748      Do this multiplication as signed, then convert to the appropriate
2749      pointer type (actually unsigned integral).  */
2750
2751   intop = convert (result_type,
2752                    build_binary_op (MULT_EXPR, intop,
2753                                     convert (TREE_TYPE (intop), size_exp), 1));
2754
2755   /* Create the sum or difference.  */
2756
2757   result = build (resultcode, result_type, ptrop, intop);
2758
2759   folded = fold (result);
2760   if (folded == result)
2761     TREE_CONSTANT (folded) = TREE_CONSTANT (ptrop) & TREE_CONSTANT (intop);
2762   return folded;
2763 }
2764
2765 /* Return a tree for the difference of pointers OP0 and OP1.
2766    The resulting tree has type int.  */
2767
2768 static tree
2769 pointer_diff (op0, op1)
2770      register tree op0, op1;
2771 {
2772   register tree result, folded;
2773   tree restype = ptrdiff_type_node;
2774
2775   tree target_type = TREE_TYPE (TREE_TYPE (op0));
2776
2777   if (pedantic || warn_pointer_arith)
2778     {
2779       if (TREE_CODE (target_type) == VOID_TYPE)
2780         pedwarn ("pointer of type `void *' used in subtraction");
2781       if (TREE_CODE (target_type) == FUNCTION_TYPE)
2782         pedwarn ("pointer to a function used in subtraction");
2783     }
2784
2785   /* First do the subtraction as integers;
2786      then drop through to build the divide operator.
2787      Do not do default conversions on the minus operator
2788      in case restype is a short type.  */
2789
2790   op0 = build_binary_op (MINUS_EXPR, convert (restype, op0),
2791                          convert (restype, op1), 0);
2792   /* This generates an error if op1 is pointer to incomplete type.  */
2793   if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (TREE_TYPE (op1))))
2794     error ("arithmetic on pointer to an incomplete type");
2795
2796   /* This generates an error if op0 is pointer to incomplete type.  */
2797   op1 = c_size_in_bytes (target_type);
2798
2799   /* Divide by the size, in easiest possible way.  */
2800
2801   result = build (EXACT_DIV_EXPR, restype, op0, convert (restype, op1));
2802
2803   folded = fold (result);
2804   if (folded == result)
2805     TREE_CONSTANT (folded) = TREE_CONSTANT (op0) & TREE_CONSTANT (op1);
2806   return folded;
2807 }
2808 \f
2809 /* Construct and perhaps optimize a tree representation
2810    for a unary operation.  CODE, a tree_code, specifies the operation
2811    and XARG is the operand.  NOCONVERT nonzero suppresses
2812    the default promotions (such as from short to int).  */
2813
2814 tree
2815 build_unary_op (code, xarg, noconvert)
2816      enum tree_code code;
2817      tree xarg;
2818      int noconvert;
2819 {
2820   /* No default_conversion here.  It causes trouble for ADDR_EXPR.  */
2821   register tree arg = xarg;
2822   register tree argtype = 0;
2823   register enum tree_code typecode = TREE_CODE (TREE_TYPE (arg));
2824   tree val;
2825
2826   if (typecode == ERROR_MARK)
2827     return error_mark_node;
2828   if (typecode == ENUMERAL_TYPE || typecode == BOOLEAN_TYPE)
2829     typecode = INTEGER_TYPE;
2830
2831   switch (code)
2832     {
2833     case CONVERT_EXPR:
2834       /* This is used for unary plus, because a CONVERT_EXPR
2835          is enough to prevent anybody from looking inside for
2836          associativity, but won't generate any code.  */
2837       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2838             || typecode == COMPLEX_TYPE))
2839         {
2840           error ("wrong type argument to unary plus");
2841           return error_mark_node;
2842         }
2843       else if (!noconvert)
2844         arg = default_conversion (arg);
2845       break;
2846
2847     case NEGATE_EXPR:
2848       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2849             || typecode == COMPLEX_TYPE))
2850         {
2851           error ("wrong type argument to unary minus");
2852           return error_mark_node;
2853         }
2854       else if (!noconvert)
2855         arg = default_conversion (arg);
2856       break;
2857
2858     case BIT_NOT_EXPR:
2859       if (typecode == COMPLEX_TYPE)
2860         {
2861           code = CONJ_EXPR;
2862           if (pedantic)
2863             pedwarn ("ISO C does not support `~' for complex conjugation");
2864           if (!noconvert)
2865             arg = default_conversion (arg);
2866         }
2867       else if (typecode != INTEGER_TYPE)
2868         {
2869           error ("wrong type argument to bit-complement");
2870           return error_mark_node;
2871         }
2872       else if (!noconvert)
2873         arg = default_conversion (arg);
2874       break;
2875
2876     case ABS_EXPR:
2877       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2878             || typecode == COMPLEX_TYPE))
2879         {
2880           error ("wrong type argument to abs");
2881           return error_mark_node;
2882         }
2883       else if (!noconvert)
2884         arg = default_conversion (arg);
2885       break;
2886
2887     case CONJ_EXPR:
2888       /* Conjugating a real value is a no-op, but allow it anyway.  */
2889       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2890             || typecode == COMPLEX_TYPE))
2891         {
2892           error ("wrong type argument to conjugation");
2893           return error_mark_node;
2894         }
2895       else if (!noconvert)
2896         arg = default_conversion (arg);
2897       break;
2898
2899     case TRUTH_NOT_EXPR:
2900       if (typecode != INTEGER_TYPE
2901           && typecode != REAL_TYPE && typecode != POINTER_TYPE
2902           && typecode != COMPLEX_TYPE
2903           /* These will convert to a pointer.  */
2904           && typecode != ARRAY_TYPE && typecode != FUNCTION_TYPE)
2905         {
2906           error ("wrong type argument to unary exclamation mark");
2907           return error_mark_node;
2908         }
2909       arg = truthvalue_conversion (arg);
2910       return invert_truthvalue (arg);
2911
2912     case NOP_EXPR:
2913       break;
2914
2915     case REALPART_EXPR:
2916       if (TREE_CODE (arg) == COMPLEX_CST)
2917         return TREE_REALPART (arg);
2918       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
2919         return fold (build1 (REALPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg));
2920       else
2921         return arg;
2922
2923     case IMAGPART_EXPR:
2924       if (TREE_CODE (arg) == COMPLEX_CST)
2925         return TREE_IMAGPART (arg);
2926       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
2927         return fold (build1 (IMAGPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg));
2928       else
2929         return convert (TREE_TYPE (arg), integer_zero_node);
2930
2931     case PREINCREMENT_EXPR:
2932     case POSTINCREMENT_EXPR:
2933     case PREDECREMENT_EXPR:
2934     case POSTDECREMENT_EXPR:
2935       /* Handle complex lvalues (when permitted)
2936          by reduction to simpler cases.  */
2937
2938       val = unary_complex_lvalue (code, arg);
2939       if (val != 0)
2940         return val;
2941
2942       /* Increment or decrement the real part of the value,
2943          and don't change the imaginary part.  */
2944       if (typecode == COMPLEX_TYPE)
2945         {
2946           tree real, imag;
2947
2948           if (pedantic)
2949             pedwarn ("ISO C does not support `++' and `--' on complex types");
2950
2951           arg = stabilize_reference (arg);
2952           real = build_unary_op (REALPART_EXPR, arg, 1);
2953           imag = build_unary_op (IMAGPART_EXPR, arg, 1);
2954           return build (COMPLEX_EXPR, TREE_TYPE (arg),
2955                         build_unary_op (code, real, 1), imag);
2956         }
2957
2958       /* Report invalid types.  */
2959
2960       if (typecode != POINTER_TYPE
2961           && typecode != INTEGER_TYPE && typecode != REAL_TYPE)
2962         {
2963           error ("wrong type argument to %s",
2964                  code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR
2965                  ? "increment" : "decrement");
2966           return error_mark_node;
2967         }
2968
2969       {
2970         register tree inc;
2971         tree result_type = TREE_TYPE (arg);
2972
2973         arg = get_unwidened (arg, 0);
2974         argtype = TREE_TYPE (arg);
2975
2976         /* Compute the increment.  */
2977
2978         if (typecode == POINTER_TYPE)
2979           {
2980             /* If pointer target is an undefined struct,
2981                we just cannot know how to do the arithmetic.  */
2982             if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (result_type)))
2983               error ("%s of pointer to unknown structure",
2984                      code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR
2985                      ? "increment" : "decrement");
2986             else if ((pedantic || warn_pointer_arith)
2987                      && (TREE_CODE (TREE_TYPE (result_type)) == FUNCTION_TYPE
2988                          || TREE_CODE (TREE_TYPE (result_type)) == VOID_TYPE))
2989               pedwarn ("wrong type argument to %s",
2990                        code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR
2991                        ? "increment" : "decrement");
2992             inc = c_size_in_bytes (TREE_TYPE (result_type));
2993           }
2994         else
2995           inc = integer_one_node;
2996
2997         inc = convert (argtype, inc);
2998
2999         /* Handle incrementing a cast-expression.  */
3000
3001         while (1)
3002           switch (TREE_CODE (arg))
3003             {
3004             case NOP_EXPR:
3005             case CONVERT_EXPR:
3006             case FLOAT_EXPR:
3007             case FIX_TRUNC_EXPR:
3008             case FIX_FLOOR_EXPR:
3009             case FIX_ROUND_EXPR:
3010             case FIX_CEIL_EXPR:
3011               pedantic_lvalue_warning (CONVERT_EXPR);
3012               /* If the real type has the same machine representation
3013                  as the type it is cast to, we can make better output
3014                  by adding directly to the inside of the cast.  */
3015               if ((TREE_CODE (TREE_TYPE (arg))
3016                    == TREE_CODE (TREE_TYPE (TREE_OPERAND (arg, 0))))
3017                   && (TYPE_MODE (TREE_TYPE (arg))
3018                       == TYPE_MODE (TREE_TYPE (TREE_OPERAND (arg, 0)))))
3019                 arg = TREE_OPERAND (arg, 0);
3020               else
3021                 {
3022                   tree incremented, modify, value;
3023                   if (TREE_CODE (TREE_TYPE (arg)) == BOOLEAN_TYPE)
3024                     value = boolean_increment (code, arg);
3025                   else
3026                     {
3027                       arg = stabilize_reference (arg);
3028                       if (code == PREINCREMENT_EXPR || code == PREDECREMENT_EXPR)
3029                         value = arg;
3030                       else
3031                         value = save_expr (arg);
3032                       incremented = build (((code == PREINCREMENT_EXPR
3033                                              || code == POSTINCREMENT_EXPR)
3034                                             ? PLUS_EXPR : MINUS_EXPR),
3035                                            argtype, value, inc);
3036                       TREE_SIDE_EFFECTS (incremented) = 1;
3037                       modify = build_modify_expr (arg, NOP_EXPR, incremented);
3038                       value = build (COMPOUND_EXPR, TREE_TYPE (arg), modify, value);
3039                     }
3040                   TREE_USED (value) = 1;
3041                   return value;
3042                 }
3043               break;
3044
3045             default:
3046               goto give_up;
3047             }
3048       give_up:
3049
3050         /* Complain about anything else that is not a true lvalue.  */
3051         if (!lvalue_or_else (arg, ((code == PREINCREMENT_EXPR
3052                                     || code == POSTINCREMENT_EXPR)
3053                                    ? "invalid lvalue in increment"
3054                                    : "invalid lvalue in decrement")))
3055           return error_mark_node;
3056
3057         /* Report a read-only lvalue.  */
3058         if (TREE_READONLY (arg))
3059           readonly_warning (arg,
3060                             ((code == PREINCREMENT_EXPR
3061                               || code == POSTINCREMENT_EXPR)
3062                              ? "increment" : "decrement"));
3063
3064         if (TREE_CODE (TREE_TYPE (arg)) == BOOLEAN_TYPE)
3065           val = boolean_increment (code, arg);
3066         else
3067           val = build (code, TREE_TYPE (arg), arg, inc);
3068         TREE_SIDE_EFFECTS (val) = 1;
3069         val = convert (result_type, val);
3070         if (TREE_CODE (val) != code)
3071           TREE_NO_UNUSED_WARNING (val) = 1;
3072         return val;
3073       }
3074
3075     case ADDR_EXPR:
3076       /* Note that this operation never does default_conversion
3077          regardless of NOCONVERT.  */
3078
3079       /* Let &* cancel out to simplify resulting code.  */
3080       if (TREE_CODE (arg) == INDIRECT_REF)
3081         {
3082           /* Don't let this be an lvalue.  */
3083           if (lvalue_p (TREE_OPERAND (arg, 0)))
3084             return non_lvalue (TREE_OPERAND (arg, 0));
3085           return TREE_OPERAND (arg, 0);
3086         }
3087
3088       /* For &x[y], return x+y */
3089       if (TREE_CODE (arg) == ARRAY_REF)
3090         {
3091           if (mark_addressable (TREE_OPERAND (arg, 0)) == 0)
3092             return error_mark_node;
3093           return build_binary_op (PLUS_EXPR, TREE_OPERAND (arg, 0),
3094                                   TREE_OPERAND (arg, 1), 1);
3095         }
3096
3097       /* Handle complex lvalues (when permitted)
3098          by reduction to simpler cases.  */
3099       val = unary_complex_lvalue (code, arg);
3100       if (val != 0)
3101         return val;
3102
3103 #if 0 /* Turned off because inconsistent;
3104          float f; *&(int)f = 3.4 stores in int format
3105          whereas (int)f = 3.4 stores in float format.  */
3106       /* Address of a cast is just a cast of the address
3107          of the operand of the cast.  */
3108       switch (TREE_CODE (arg))
3109         {
3110         case NOP_EXPR:
3111         case CONVERT_EXPR:
3112         case FLOAT_EXPR:
3113         case FIX_TRUNC_EXPR:
3114         case FIX_FLOOR_EXPR:
3115         case FIX_ROUND_EXPR:
3116         case FIX_CEIL_EXPR:
3117           if (pedantic)
3118             pedwarn ("ISO C forbids the address of a cast expression");
3119           return convert (build_pointer_type (TREE_TYPE (arg)),
3120                           build_unary_op (ADDR_EXPR, TREE_OPERAND (arg, 0),
3121                                           0));
3122         }
3123 #endif
3124
3125       /* Allow the address of a constructor if all the elements
3126          are constant.  */
3127       if (TREE_CODE (arg) == CONSTRUCTOR && TREE_CONSTANT (arg))
3128         ;
3129       /* Anything not already handled and not a true memory reference
3130          is an error.  */
3131       else if (typecode != FUNCTION_TYPE
3132                && !lvalue_or_else (arg, "invalid lvalue in unary `&'"))
3133         return error_mark_node;
3134
3135       /* Ordinary case; arg is a COMPONENT_REF or a decl.  */
3136       argtype = TREE_TYPE (arg);
3137
3138       /* If the lvalue is const or volatile, merge that into the type
3139          to which the address will point.  Note that you can't get a
3140          restricted pointer by taking the address of something, so we
3141          only have to deal with `const' and `volatile' here.  */
3142       if ((DECL_P (arg) || TREE_CODE_CLASS (TREE_CODE (arg)) == 'r')
3143           && (TREE_READONLY (arg) || TREE_THIS_VOLATILE (arg)))
3144           argtype = c_build_type_variant (argtype,
3145                                           TREE_READONLY (arg),
3146                                           TREE_THIS_VOLATILE (arg));
3147
3148       argtype = build_pointer_type (argtype);
3149
3150       if (mark_addressable (arg) == 0)
3151         return error_mark_node;
3152
3153       {
3154         tree addr;
3155
3156         if (TREE_CODE (arg) == COMPONENT_REF)
3157           {
3158             tree field = TREE_OPERAND (arg, 1);
3159
3160             addr = build_unary_op (ADDR_EXPR, TREE_OPERAND (arg, 0), 0);
3161
3162             if (DECL_C_BIT_FIELD (field))
3163               {
3164                 error ("attempt to take address of bit-field structure member `%s'",
3165                        IDENTIFIER_POINTER (DECL_NAME (field)));
3166                 return error_mark_node;
3167               }
3168
3169             addr = fold (build (PLUS_EXPR, argtype,
3170                                 convert (argtype, addr),
3171                                 convert (argtype, byte_position (field))));
3172           }
3173         else
3174           addr = build1 (code, argtype, arg);
3175
3176         /* Address of a static or external variable or
3177            file-scope function counts as a constant.  */
3178         if (staticp (arg)
3179             && ! (TREE_CODE (arg) == FUNCTION_DECL
3180                   && DECL_CONTEXT (arg) != 0))
3181           TREE_CONSTANT (addr) = 1;
3182         return addr;
3183       }
3184
3185     default:
3186       break;
3187     }
3188
3189   if (argtype == 0)
3190     argtype = TREE_TYPE (arg);
3191   return fold (build1 (code, argtype, arg));
3192 }
3193
3194 #if 0
3195 /* If CONVERSIONS is a conversion expression or a nested sequence of such,
3196    convert ARG with the same conversions in the same order
3197    and return the result.  */
3198
3199 static tree
3200 convert_sequence (conversions, arg)
3201      tree conversions;
3202      tree arg;
3203 {
3204   switch (TREE_CODE (conversions))
3205     {
3206     case NOP_EXPR:
3207     case CONVERT_EXPR:
3208     case FLOAT_EXPR:
3209     case FIX_TRUNC_EXPR:
3210     case FIX_FLOOR_EXPR:
3211     case FIX_ROUND_EXPR:
3212     case FIX_CEIL_EXPR:
3213       return convert (TREE_TYPE (conversions),
3214                       convert_sequence (TREE_OPERAND (conversions, 0),
3215                                         arg));
3216
3217     default:
3218       return arg;
3219     }
3220 }
3221 #endif /* 0 */
3222
3223 /* Return nonzero if REF is an lvalue valid for this language.
3224    Lvalues can be assigned, unless their type has TYPE_READONLY.
3225    Lvalues can have their address taken, unless they have DECL_REGISTER.  */
3226
3227 int
3228 lvalue_p (ref)
3229      tree ref;
3230 {
3231   register enum tree_code code = TREE_CODE (ref);
3232
3233   switch (code)
3234     {
3235     case REALPART_EXPR:
3236     case IMAGPART_EXPR:
3237     case COMPONENT_REF:
3238       return lvalue_p (TREE_OPERAND (ref, 0));
3239
3240     case STRING_CST:
3241       return 1;
3242
3243     case INDIRECT_REF:
3244     case ARRAY_REF:
3245     case VAR_DECL:
3246     case PARM_DECL:
3247     case RESULT_DECL:
3248     case ERROR_MARK:
3249       return (TREE_CODE (TREE_TYPE (ref)) != FUNCTION_TYPE
3250               && TREE_CODE (TREE_TYPE (ref)) != METHOD_TYPE);
3251
3252     case BIND_EXPR:
3253     case RTL_EXPR:
3254       return TREE_CODE (TREE_TYPE (ref)) == ARRAY_TYPE;
3255
3256     default:
3257       return 0;
3258     }
3259 }
3260
3261 /* Return nonzero if REF is an lvalue valid for this language;
3262    otherwise, print an error message and return zero.  */
3263
3264 int
3265 lvalue_or_else (ref, msgid)
3266      tree ref;
3267      const char *msgid;
3268 {
3269   int win = lvalue_p (ref);
3270
3271   if (! win)
3272     error ("%s", msgid);
3273
3274   return win;
3275 }
3276
3277 /* Apply unary lvalue-demanding operator CODE to the expression ARG
3278    for certain kinds of expressions which are not really lvalues
3279    but which we can accept as lvalues.
3280
3281    If ARG is not a kind of expression we can handle, return zero.  */
3282
3283 static tree
3284 unary_complex_lvalue (code, arg)
3285      enum tree_code code;
3286      tree arg;
3287 {
3288   /* Handle (a, b) used as an "lvalue".  */
3289   if (TREE_CODE (arg) == COMPOUND_EXPR)
3290     {
3291       tree real_result = build_unary_op (code, TREE_OPERAND (arg, 1), 0);
3292
3293       /* If this returns a function type, it isn't really being used as
3294          an lvalue, so don't issue a warning about it.  */
3295       if (TREE_CODE (TREE_TYPE (arg)) != FUNCTION_TYPE)
3296         pedantic_lvalue_warning (COMPOUND_EXPR);
3297
3298       return build (COMPOUND_EXPR, TREE_TYPE (real_result),
3299                     TREE_OPERAND (arg, 0), real_result);
3300     }
3301
3302   /* Handle (a ? b : c) used as an "lvalue".  */
3303   if (TREE_CODE (arg) == COND_EXPR)
3304     {
3305       pedantic_lvalue_warning (COND_EXPR);
3306       if (TREE_CODE (TREE_TYPE (arg)) != FUNCTION_TYPE)
3307         pedantic_lvalue_warning (COMPOUND_EXPR);
3308
3309       return (build_conditional_expr
3310               (TREE_OPERAND (arg, 0),
3311                build_unary_op (code, TREE_OPERAND (arg, 1), 0),
3312                build_unary_op (code, TREE_OPERAND (arg, 2), 0)));
3313     }
3314
3315   return 0;
3316 }
3317
3318 /* If pedantic, warn about improper lvalue.   CODE is either COND_EXPR
3319    COMPOUND_EXPR, or CONVERT_EXPR (for casts).  */
3320
3321 static void
3322 pedantic_lvalue_warning (code)
3323      enum tree_code code;
3324 {
3325   if (pedantic)
3326     switch (code)
3327       {
3328       case COND_EXPR:
3329         pedwarn ("ISO C forbids use of conditional expressions as lvalues");
3330         break;
3331       case COMPOUND_EXPR:
3332         pedwarn ("ISO C forbids use of compound expressions as lvalues");
3333         break;
3334       default:
3335         pedwarn ("ISO C forbids use of cast expressions as lvalues");
3336         break;
3337       }
3338 }
3339 \f
3340 /* Warn about storing in something that is `const'.  */
3341
3342 void
3343 readonly_warning (arg, msgid)
3344      tree arg;
3345      const char *msgid;
3346 {
3347   if (TREE_CODE (arg) == COMPONENT_REF)
3348     {
3349       if (TYPE_READONLY (TREE_TYPE (TREE_OPERAND (arg, 0))))
3350         readonly_warning (TREE_OPERAND (arg, 0), msgid);
3351       else
3352         pedwarn ("%s of read-only member `%s'", _(msgid),
3353                  IDENTIFIER_POINTER (DECL_NAME (TREE_OPERAND (arg, 1))));
3354     }
3355   else if (TREE_CODE (arg) == VAR_DECL)
3356     pedwarn ("%s of read-only variable `%s'", _(msgid),
3357              IDENTIFIER_POINTER (DECL_NAME (arg)));
3358   else
3359     pedwarn ("%s of read-only location", _(msgid));
3360 }
3361 \f
3362 /* Mark EXP saying that we need to be able to take the
3363    address of it; it should not be allocated in a register.
3364    Value is 1 if successful.  */
3365
3366 int
3367 mark_addressable (exp)
3368      tree exp;
3369 {
3370   register tree x = exp;
3371   while (1)
3372     switch (TREE_CODE (x))
3373       {
3374       case COMPONENT_REF:
3375         if (DECL_C_BIT_FIELD (TREE_OPERAND (x, 1)))
3376           {
3377             error ("cannot take address of bitfield `%s'",
3378                    IDENTIFIER_POINTER (DECL_NAME (TREE_OPERAND (x, 1))));
3379             return 0;
3380           }
3381
3382         /* ... fall through ...  */
3383
3384       case ADDR_EXPR:
3385       case ARRAY_REF:
3386       case REALPART_EXPR:
3387       case IMAGPART_EXPR:
3388         x = TREE_OPERAND (x, 0);
3389         break;
3390
3391       case CONSTRUCTOR:
3392         TREE_ADDRESSABLE (x) = 1;
3393         return 1;
3394
3395       case VAR_DECL:
3396       case CONST_DECL:
3397       case PARM_DECL:
3398       case RESULT_DECL:
3399         if (DECL_REGISTER (x) && !TREE_ADDRESSABLE (x)
3400             && DECL_NONLOCAL (x))
3401           {
3402             if (TREE_PUBLIC (x))
3403               {
3404                 error ("global register variable `%s' used in nested function",
3405                        IDENTIFIER_POINTER (DECL_NAME (x)));
3406                 return 0;
3407               }
3408             pedwarn ("register variable `%s' used in nested function",
3409                      IDENTIFIER_POINTER (DECL_NAME (x)));
3410           }
3411         else if (DECL_REGISTER (x) && !TREE_ADDRESSABLE (x))
3412           {
3413             if (TREE_PUBLIC (x))
3414               {
3415                 error ("address of global register variable `%s' requested",
3416                        IDENTIFIER_POINTER (DECL_NAME (x)));
3417                 return 0;
3418               }
3419
3420             /* If we are making this addressable due to its having
3421                volatile components, give a different error message.  Also
3422                handle the case of an unnamed parameter by not trying
3423                to give the name.  */
3424
3425             else if (C_TYPE_FIELDS_VOLATILE (TREE_TYPE (x)))
3426               {
3427                 error ("cannot put object with volatile field into register");
3428                 return 0;
3429               }
3430
3431             pedwarn ("address of register variable `%s' requested",
3432                      IDENTIFIER_POINTER (DECL_NAME (x)));
3433           }
3434         put_var_into_stack (x);
3435
3436         /* drops in */
3437       case FUNCTION_DECL:
3438         TREE_ADDRESSABLE (x) = 1;
3439 #if 0  /* poplevel deals with this now.  */
3440         if (DECL_CONTEXT (x) == 0)
3441           TREE_ADDRESSABLE (DECL_ASSEMBLER_NAME (x)) = 1;
3442 #endif
3443
3444       default:
3445         return 1;
3446     }
3447 }
3448 \f
3449 /* Build and return a conditional expression IFEXP ? OP1 : OP2.  */
3450
3451 tree
3452 build_conditional_expr (ifexp, op1, op2)
3453      tree ifexp, op1, op2;
3454 {
3455   register tree type1;
3456   register tree type2;
3457   register enum tree_code code1;
3458   register enum tree_code code2;
3459   register tree result_type = NULL;
3460   tree orig_op1 = op1, orig_op2 = op2;
3461
3462   ifexp = truthvalue_conversion (default_conversion (ifexp));
3463
3464 #if 0 /* Produces wrong result if within sizeof.  */
3465   /* Don't promote the operands separately if they promote
3466      the same way.  Return the unpromoted type and let the combined
3467      value get promoted if necessary.  */
3468
3469   if (TREE_TYPE (op1) == TREE_TYPE (op2)
3470       && TREE_CODE (TREE_TYPE (op1)) != ARRAY_TYPE
3471       && TREE_CODE (TREE_TYPE (op1)) != ENUMERAL_TYPE
3472       && TREE_CODE (TREE_TYPE (op1)) != FUNCTION_TYPE)
3473     {
3474       if (TREE_CODE (ifexp) == INTEGER_CST)
3475         return pedantic_non_lvalue (integer_zerop (ifexp) ? op2 : op1);
3476
3477       return fold (build (COND_EXPR, TREE_TYPE (op1), ifexp, op1, op2));
3478     }
3479 #endif
3480
3481   /* Promote both alternatives.  */
3482
3483   if (TREE_CODE (TREE_TYPE (op1)) != VOID_TYPE)
3484     op1 = default_conversion (op1);
3485   if (TREE_CODE (TREE_TYPE (op2)) != VOID_TYPE)
3486     op2 = default_conversion (op2);
3487
3488   if (TREE_CODE (ifexp) == ERROR_MARK
3489       || TREE_CODE (TREE_TYPE (op1)) == ERROR_MARK
3490       || TREE_CODE (TREE_TYPE (op2)) == ERROR_MARK)
3491     return error_mark_node;
3492
3493   type1 = TREE_TYPE (op1);
3494   code1 = TREE_CODE (type1);
3495   type2 = TREE_TYPE (op2);
3496   code2 = TREE_CODE (type2);
3497
3498   /* Quickly detect the usual case where op1 and op2 have the same type
3499      after promotion.  */
3500   if (TYPE_MAIN_VARIANT (type1) == TYPE_MAIN_VARIANT (type2))
3501     {
3502       if (type1 == type2)
3503         result_type = type1;
3504       else
3505         result_type = TYPE_MAIN_VARIANT (type1);
3506     }
3507   else if ((code1 == INTEGER_TYPE || code1 == REAL_TYPE
3508             || code1 == COMPLEX_TYPE)
3509            && (code2 == INTEGER_TYPE || code2 == REAL_TYPE
3510                || code2 == COMPLEX_TYPE))
3511     {
3512       result_type = common_type (type1, type2);
3513
3514       /* If -Wsign-compare, warn here if type1 and type2 have
3515          different signedness.  We'll promote the signed to unsigned
3516          and later code won't know it used to be different.
3517          Do this check on the original types, so that explicit casts
3518          will be considered, but default promotions won't.  */
3519       if ((warn_sign_compare < 0 ? extra_warnings : warn_sign_compare)
3520           && !skip_evaluation)
3521         {
3522           int unsigned_op1 = TREE_UNSIGNED (TREE_TYPE (orig_op1));
3523           int unsigned_op2 = TREE_UNSIGNED (TREE_TYPE (orig_op2));
3524
3525           if (unsigned_op1 ^ unsigned_op2)
3526             {
3527               /* Do not warn if the result type is signed, since the
3528                  signed type will only be chosen if it can represent
3529                  all the values of the unsigned type.  */
3530               if (! TREE_UNSIGNED (result_type))
3531                 /* OK */;
3532               /* Do not warn if the signed quantity is an unsuffixed
3533                  integer literal (or some static constant expression
3534                  involving such literals) and it is non-negative.  */
3535               else if ((unsigned_op2 && tree_expr_nonnegative_p (op1))
3536                        || (unsigned_op1 && tree_expr_nonnegative_p (op2)))
3537                 /* OK */;
3538               else
3539                 warning ("signed and unsigned type in conditional expression");
3540             }
3541         }
3542     }
3543   else if (code1 == VOID_TYPE || code2 == VOID_TYPE)
3544     {
3545       if (pedantic && (code1 != VOID_TYPE || code2 != VOID_TYPE))
3546         pedwarn ("ISO C forbids conditional expr with only one void side");
3547       result_type = void_type_node;
3548     }
3549   else if (code1 == POINTER_TYPE && code2 == POINTER_TYPE)
3550     {
3551       if (comp_target_types (type1, type2))
3552         result_type = common_type (type1, type2);
3553       else if (integer_zerop (op1) && TREE_TYPE (type1) == void_type_node
3554                && TREE_CODE (orig_op1) != NOP_EXPR)
3555         result_type = qualify_type (type2, type1);
3556       else if (integer_zerop (op2) && TREE_TYPE (type2) == void_type_node
3557                && TREE_CODE (orig_op2) != NOP_EXPR)
3558         result_type = qualify_type (type1, type2);
3559       else if (VOID_TYPE_P (TREE_TYPE (type1)))
3560         {
3561           if (pedantic && TREE_CODE (TREE_TYPE (type2)) == FUNCTION_TYPE)
3562             pedwarn ("ISO C forbids conditional expr between `void *' and function pointer");
3563           result_type = build_pointer_type (qualify_type (TREE_TYPE (type1),
3564                                                           TREE_TYPE (type2)));
3565         }
3566       else if (VOID_TYPE_P (TREE_TYPE (type2)))
3567         {
3568           if (pedantic && TREE_CODE (TREE_TYPE (type1)) == FUNCTION_TYPE)
3569             pedwarn ("ISO C forbids conditional expr between `void *' and function pointer");
3570           result_type = build_pointer_type (qualify_type (TREE_TYPE (type2),
3571                                                           TREE_TYPE (type1)));
3572         }
3573       else
3574         {
3575           pedwarn ("pointer type mismatch in conditional expression");
3576           result_type = build_pointer_type (void_type_node);
3577         }
3578     }
3579   else if (code1 == POINTER_TYPE && code2 == INTEGER_TYPE)
3580     {
3581       if (! integer_zerop (op2))
3582         pedwarn ("pointer/integer type mismatch in conditional expression");
3583       else
3584         {
3585           op2 = null_pointer_node;
3586         }
3587       result_type = type1;
3588     }
3589   else if (code2 == POINTER_TYPE && code1 == INTEGER_TYPE)
3590     {
3591       if (!integer_zerop (op1))
3592         pedwarn ("pointer/integer type mismatch in conditional expression");
3593       else
3594         {
3595           op1 = null_pointer_node;
3596         }
3597       result_type = type2;
3598     }
3599
3600   if (!result_type)
3601     {
3602       if (flag_cond_mismatch)
3603         result_type = void_type_node;
3604       else
3605         {
3606           error ("type mismatch in conditional expression");
3607           return error_mark_node;
3608         }
3609     }
3610
3611   /* Merge const and volatile flags of the incoming types.  */
3612   result_type
3613     = build_type_variant (result_type,
3614                           TREE_READONLY (op1) || TREE_READONLY (op2),
3615                           TREE_THIS_VOLATILE (op1) || TREE_THIS_VOLATILE (op2));
3616
3617   if (result_type != TREE_TYPE (op1))
3618     op1 = convert_and_check (result_type, op1);
3619   if (result_type != TREE_TYPE (op2))
3620     op2 = convert_and_check (result_type, op2);
3621
3622   if (TREE_CODE (ifexp) == INTEGER_CST)
3623     return pedantic_non_lvalue (integer_zerop (ifexp) ? op2 : op1);
3624
3625   return fold (build (COND_EXPR, result_type, ifexp, op1, op2));
3626 }
3627 \f
3628 /* Given a list of expressions, return a compound expression
3629    that performs them all and returns the value of the last of them.  */
3630
3631 tree
3632 build_compound_expr (list)
3633      tree list;
3634 {
3635   return internal_build_compound_expr (list, TRUE);
3636 }
3637
3638 static tree
3639 internal_build_compound_expr (list, first_p)
3640      tree list;
3641      int first_p;
3642 {
3643   register tree rest;
3644
3645   if (TREE_CHAIN (list) == 0)
3646     {
3647       /* Convert arrays to pointers when there really is a comma operator.  */
3648       if (!first_p && TREE_CODE (TREE_TYPE (TREE_VALUE (list))) == ARRAY_TYPE)
3649         TREE_VALUE (list) = default_conversion (TREE_VALUE (list));
3650
3651 #if 0 /* If something inside inhibited lvalueness, we should not override.  */
3652       /* Consider (x, y+0), which is not an lvalue since y+0 is not.  */
3653
3654       /* Strip NON_LVALUE_EXPRs since we aren't using as an lvalue.  */
3655       if (TREE_CODE (list) == NON_LVALUE_EXPR)
3656         list = TREE_OPERAND (list, 0);
3657 #endif
3658
3659       /* Don't let (0, 0) be null pointer constant.  */
3660       if (!first_p && integer_zerop (TREE_VALUE (list)))
3661         return non_lvalue (TREE_VALUE (list));
3662       return TREE_VALUE (list);
3663     }
3664
3665   rest = internal_build_compound_expr (TREE_CHAIN (list), FALSE);
3666
3667   if (! TREE_SIDE_EFFECTS (TREE_VALUE (list)))
3668     {
3669       /* The left-hand operand of a comma expression is like an expression
3670          statement: with -W or -Wunused, we should warn if it doesn't have
3671          any side-effects, unless it was explicitly cast to (void).  */
3672       if ((extra_warnings || warn_unused_value)
3673            && ! (TREE_CODE (TREE_VALUE (list)) == CONVERT_EXPR
3674                 && VOID_TYPE_P (TREE_TYPE (TREE_VALUE (list)))))
3675         warning ("left-hand operand of comma expression has no effect");
3676
3677       /* When pedantic, a compound expression can be neither an lvalue
3678          nor an integer constant expression.  */
3679       if (! pedantic)
3680         return rest;
3681     }
3682
3683   /* With -Wunused, we should also warn if the left-hand operand does have
3684      side-effects, but computes a value which is not used.  For example, in
3685      `foo() + bar(), baz()' the result of the `+' operator is not used,
3686      so we should issue a warning.  */
3687   else if (warn_unused_value)
3688     warn_if_unused_value (TREE_VALUE (list));
3689
3690   return build (COMPOUND_EXPR, TREE_TYPE (rest), TREE_VALUE (list), rest);
3691 }
3692
3693 /* Build an expression representing a cast to type TYPE of expression EXPR.  */
3694
3695 tree
3696 build_c_cast (type, expr)
3697      register tree type;
3698      tree expr;
3699 {
3700   register tree value = expr;
3701
3702   if (type == error_mark_node || expr == error_mark_node)
3703     return error_mark_node;
3704   type = TYPE_MAIN_VARIANT (type);
3705
3706 #if 0
3707   /* Strip NON_LVALUE_EXPRs since we aren't using as an lvalue.  */
3708   if (TREE_CODE (value) == NON_LVALUE_EXPR)
3709     value = TREE_OPERAND (value, 0);
3710 #endif
3711
3712   if (TREE_CODE (type) == ARRAY_TYPE)
3713     {
3714       error ("cast specifies array type");
3715       return error_mark_node;
3716     }
3717
3718   if (TREE_CODE (type) == FUNCTION_TYPE)
3719     {
3720       error ("cast specifies function type");
3721       return error_mark_node;
3722     }
3723
3724   if (type == TREE_TYPE (value))
3725     {
3726       if (pedantic)
3727         {
3728           if (TREE_CODE (type) == RECORD_TYPE
3729               || TREE_CODE (type) == UNION_TYPE)
3730             pedwarn ("ISO C forbids casting nonscalar to the same type");
3731         }
3732     }
3733   else if (TREE_CODE (type) == UNION_TYPE)
3734     {
3735       tree field;
3736       if (TREE_CODE (TREE_TYPE (value)) == ARRAY_TYPE
3737           || TREE_CODE (TREE_TYPE (value)) == FUNCTION_TYPE)
3738         value = default_conversion (value);
3739
3740       for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
3741         if (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (field)),
3742                        TYPE_MAIN_VARIANT (TREE_TYPE (value))))
3743           break;
3744
3745       if (field)
3746         {
3747           const char *name;
3748           tree t;
3749
3750           if (pedantic)
3751             pedwarn ("ISO C forbids casts to union type");
3752           if (TYPE_NAME (type) != 0)
3753             {
3754               if (TREE_CODE (TYPE_NAME (type)) == IDENTIFIER_NODE)
3755                 name = IDENTIFIER_POINTER (TYPE_NAME (type));
3756               else
3757                 name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (type)));
3758             }
3759           else
3760             name = "";
3761           t = digest_init (type, build (CONSTRUCTOR, type, NULL_TREE,
3762                                         build_tree_list (field, value)),
3763                            0, 0);
3764           TREE_CONSTANT (t) = TREE_CONSTANT (value);
3765           return t;
3766         }
3767       error ("cast to union type from type not present in union");
3768       return error_mark_node;
3769     }
3770   else
3771     {
3772       tree otype, ovalue;
3773
3774       /* If casting to void, avoid the error that would come
3775          from default_conversion in the case of a non-lvalue array.  */
3776       if (type == void_type_node)
3777         return build1 (CONVERT_EXPR, type, value);
3778
3779       /* Convert functions and arrays to pointers,
3780          but don't convert any other types.  */
3781       if (TREE_CODE (TREE_TYPE (value)) == FUNCTION_TYPE
3782           || TREE_CODE (TREE_TYPE (value)) == ARRAY_TYPE)
3783         value = default_conversion (value);
3784       otype = TREE_TYPE (value);
3785
3786       /* Optionally warn about potentially worrisome casts.  */
3787
3788       if (warn_cast_qual
3789           && TREE_CODE (type) == POINTER_TYPE
3790           && TREE_CODE (otype) == POINTER_TYPE)
3791         {
3792           tree in_type = type;
3793           tree in_otype = otype;
3794           int warn = 0;
3795
3796           /* Check that the qualifiers on IN_TYPE are a superset of
3797              the qualifiers of IN_OTYPE.  The outermost level of
3798              POINTER_TYPE nodes is uninteresting and we stop as soon
3799              as we hit a non-POINTER_TYPE node on either type.  */
3800           do
3801             {
3802               in_otype = TREE_TYPE (in_otype);
3803               in_type = TREE_TYPE (in_type);
3804               warn |= (TYPE_QUALS (in_otype) & ~TYPE_QUALS (in_type));
3805             }
3806           while (TREE_CODE (in_type) == POINTER_TYPE
3807                  && TREE_CODE (in_otype) == POINTER_TYPE);
3808
3809           if (warn)
3810             /* There are qualifiers present in IN_OTYPE that are not
3811                present in IN_TYPE.  */
3812             warning ("cast discards qualifiers from pointer target type");
3813         }
3814
3815       /* Warn about possible alignment problems.  */
3816       if (STRICT_ALIGNMENT && warn_cast_align
3817           && TREE_CODE (type) == POINTER_TYPE
3818           && TREE_CODE (otype) == POINTER_TYPE
3819           && TREE_CODE (TREE_TYPE (otype)) != VOID_TYPE
3820           && TREE_CODE (TREE_TYPE (otype)) != FUNCTION_TYPE
3821           /* Don't warn about opaque types, where the actual alignment
3822              restriction is unknown.  */
3823           && !((TREE_CODE (TREE_TYPE (otype)) == UNION_TYPE
3824                 || TREE_CODE (TREE_TYPE (otype)) == RECORD_TYPE)
3825                && TYPE_MODE (TREE_TYPE (otype)) == VOIDmode)
3826           && TYPE_ALIGN (TREE_TYPE (type)) > TYPE_ALIGN (TREE_TYPE (otype)))
3827         warning ("cast increases required alignment of target type");
3828
3829       if (TREE_CODE (type) == INTEGER_TYPE
3830           && TREE_CODE (otype) == POINTER_TYPE
3831           && TYPE_PRECISION (type) != TYPE_PRECISION (otype)
3832           && !TREE_CONSTANT (value))
3833         warning ("cast from pointer to integer of different size");
3834
3835       if (warn_bad_function_cast
3836           && TREE_CODE (value) == CALL_EXPR
3837           && TREE_CODE (type) != TREE_CODE (otype))
3838         warning ("cast does not match function type");
3839
3840       if (TREE_CODE (type) == POINTER_TYPE
3841           && TREE_CODE (otype) == INTEGER_TYPE
3842           && TYPE_PRECISION (type) != TYPE_PRECISION (otype)
3843           /* Don't warn about converting any constant.  */
3844           && !TREE_CONSTANT (value))
3845         warning ("cast to pointer from integer of different size");
3846
3847       ovalue = value;
3848       value = convert (type, value);
3849
3850       /* Ignore any integer overflow caused by the cast.  */
3851       if (TREE_CODE (value) == INTEGER_CST)
3852         {
3853           TREE_OVERFLOW (value) = TREE_OVERFLOW (ovalue);
3854           TREE_CONSTANT_OVERFLOW (value) = TREE_CONSTANT_OVERFLOW (ovalue);
3855         }
3856     }
3857
3858   /* Pedantically, don't ley (void *) (FOO *) 0 be a null pointer constant.  */
3859   if (pedantic && TREE_CODE (value) == INTEGER_CST
3860       && TREE_CODE (expr) == INTEGER_CST
3861       && TREE_CODE (TREE_TYPE (expr)) != INTEGER_TYPE)
3862     value = non_lvalue (value);
3863
3864   /* If pedantic, don't let a cast be an lvalue.  */
3865   if (value == expr && pedantic)
3866     value = non_lvalue (value);
3867
3868   return value;
3869 }
3870
3871 /* Interpret a cast of expression EXPR to type TYPE.  */
3872 tree
3873 c_cast_expr (type, expr)
3874      tree type, expr;
3875 {
3876   int saved_wsp = warn_strict_prototypes;
3877
3878   /* This avoids warnings about unprototyped casts on
3879      integers.  E.g. "#define SIG_DFL (void(*)())0".  */
3880   if (TREE_CODE (expr) == INTEGER_CST)
3881     warn_strict_prototypes = 0;
3882   type = groktypename (type);
3883   warn_strict_prototypes = saved_wsp;
3884
3885   return build_c_cast (type, expr);
3886 }
3887
3888 \f
3889 /* Build an assignment expression of lvalue LHS from value RHS.
3890    MODIFYCODE is the code for a binary operator that we use
3891    to combine the old value of LHS with RHS to get the new value.
3892    Or else MODIFYCODE is NOP_EXPR meaning do a simple assignment.  */
3893
3894 tree
3895 build_modify_expr (lhs, modifycode, rhs)
3896      tree lhs, rhs;
3897      enum tree_code modifycode;
3898 {
3899   register tree result;
3900   tree newrhs;
3901   tree lhstype = TREE_TYPE (lhs);
3902   tree olhstype = lhstype;
3903
3904   /* Types that aren't fully specified cannot be used in assignments.  */
3905   lhs = require_complete_type (lhs);
3906
3907   /* Avoid duplicate error messages from operands that had errors.  */
3908   if (TREE_CODE (lhs) == ERROR_MARK || TREE_CODE (rhs) == ERROR_MARK)
3909     return error_mark_node;
3910
3911   /* Strip NON_LVALUE_EXPRs since we aren't using as an lvalue.  */
3912   /* Do not use STRIP_NOPS here.  We do not want an enumerator
3913      whose value is 0 to count as a null pointer constant.  */
3914   if (TREE_CODE (rhs) == NON_LVALUE_EXPR)
3915     rhs = TREE_OPERAND (rhs, 0);
3916
3917   newrhs = rhs;
3918
3919   /* Handle control structure constructs used as "lvalues".  */
3920
3921   switch (TREE_CODE (lhs))
3922     {
3923       /* Handle (a, b) used as an "lvalue".  */
3924     case COMPOUND_EXPR:
3925       pedantic_lvalue_warning (COMPOUND_EXPR);
3926       newrhs = build_modify_expr (TREE_OPERAND (lhs, 1), modifycode, rhs);
3927       if (TREE_CODE (newrhs) == ERROR_MARK)
3928         return error_mark_node;
3929       return build (COMPOUND_EXPR, lhstype,
3930                     TREE_OPERAND (lhs, 0), newrhs);
3931
3932       /* Handle (a ? b : c) used as an "lvalue".  */
3933     case COND_EXPR:
3934       pedantic_lvalue_warning (COND_EXPR);
3935       rhs = save_expr (rhs);
3936       {
3937         /* Produce (a ? (b = rhs) : (c = rhs))
3938            except that the RHS goes through a save-expr
3939            so the code to compute it is only emitted once.  */
3940         tree cond
3941           = build_conditional_expr (TREE_OPERAND (lhs, 0),
3942                                     build_modify_expr (TREE_OPERAND (lhs, 1),
3943                                                        modifycode, rhs),
3944                                     build_modify_expr (TREE_OPERAND (lhs, 2),
3945                                                        modifycode, rhs));
3946         if (TREE_CODE (cond) == ERROR_MARK)
3947           return cond;
3948         /* Make sure the code to compute the rhs comes out
3949            before the split.  */
3950         return build (COMPOUND_EXPR, TREE_TYPE (lhs),
3951                       /* But cast it to void to avoid an "unused" error.  */
3952                       convert (void_type_node, rhs), cond);
3953       }
3954     default:
3955       break;
3956     }
3957
3958   /* If a binary op has been requested, combine the old LHS value with the RHS
3959      producing the value we should actually store into the LHS.  */
3960
3961   if (modifycode != NOP_EXPR)
3962     {
3963       lhs = stabilize_reference (lhs);
3964       newrhs = build_binary_op (modifycode, lhs, rhs, 1);
3965     }
3966
3967   /* Handle a cast used as an "lvalue".
3968      We have already performed any binary operator using the value as cast.
3969      Now convert the result to the cast type of the lhs,
3970      and then true type of the lhs and store it there;
3971      then convert result back to the cast type to be the value
3972      of the assignment.  */
3973
3974   switch (TREE_CODE (lhs))
3975     {
3976     case NOP_EXPR:
3977     case CONVERT_EXPR:
3978     case FLOAT_EXPR:
3979     case FIX_TRUNC_EXPR:
3980     case FIX_FLOOR_EXPR:
3981     case FIX_ROUND_EXPR:
3982     case FIX_CEIL_EXPR:
3983       if (TREE_CODE (TREE_TYPE (newrhs)) == ARRAY_TYPE
3984           || TREE_CODE (TREE_TYPE (newrhs)) == FUNCTION_TYPE)
3985         newrhs = default_conversion (newrhs);
3986       {
3987         tree inner_lhs = TREE_OPERAND (lhs, 0);
3988         tree result;
3989         result = build_modify_expr (inner_lhs, NOP_EXPR,
3990                                     convert (TREE_TYPE (inner_lhs),
3991                                              convert (lhstype, newrhs)));
3992         if (TREE_CODE (result) == ERROR_MARK)
3993           return result;
3994         pedantic_lvalue_warning (CONVERT_EXPR);
3995         return convert (TREE_TYPE (lhs), result);
3996       }
3997
3998     default:
3999       break;
4000     }
4001
4002   /* Now we have handled acceptable kinds of LHS that are not truly lvalues.
4003      Reject anything strange now.  */
4004
4005   if (!lvalue_or_else (lhs, "invalid lvalue in assignment"))
4006     return error_mark_node;
4007
4008   /* Warn about storing in something that is `const'.  */
4009
4010   if (TREE_READONLY (lhs) || TYPE_READONLY (lhstype)
4011       || ((TREE_CODE (lhstype) == RECORD_TYPE
4012            || TREE_CODE (lhstype) == UNION_TYPE)
4013           && C_TYPE_FIELDS_READONLY (lhstype)))
4014     readonly_warning (lhs, "assignment");
4015
4016   /* If storing into a structure or union member,
4017      it has probably been given type `int'.
4018      Compute the type that would go with
4019      the actual amount of storage the member occupies.  */
4020
4021   if (TREE_CODE (lhs) == COMPONENT_REF
4022       && (TREE_CODE (lhstype) == INTEGER_TYPE
4023           || TREE_CODE (lhstype) == BOOLEAN_TYPE
4024           || TREE_CODE (lhstype) == REAL_TYPE
4025           || TREE_CODE (lhstype) == ENUMERAL_TYPE))
4026     lhstype = TREE_TYPE (get_unwidened (lhs, 0));
4027
4028   /* If storing in a field that is in actuality a short or narrower than one,
4029      we must store in the field in its actual type.  */
4030
4031   if (lhstype != TREE_TYPE (lhs))
4032     {
4033       lhs = copy_node (lhs);
4034       TREE_TYPE (lhs) = lhstype;
4035     }
4036
4037   /* Convert new value to destination type.  */
4038
4039   newrhs = convert_for_assignment (lhstype, newrhs, _("assignment"),
4040                                    NULL_TREE, NULL_TREE, 0);
4041   if (TREE_CODE (newrhs) == ERROR_MARK)
4042     return error_mark_node;
4043
4044   /* Scan operands */
4045
4046   result = build (MODIFY_EXPR, lhstype, lhs, newrhs);
4047   TREE_SIDE_EFFECTS (result) = 1;
4048
4049   /* If we got the LHS in a different type for storing in,
4050      convert the result back to the nominal type of LHS
4051      so that the value we return always has the same type
4052      as the LHS argument.  */
4053
4054   if (olhstype == TREE_TYPE (result))
4055     return result;
4056   return convert_for_assignment (olhstype, result, _("assignment"),
4057                                  NULL_TREE, NULL_TREE, 0);
4058 }
4059 \f
4060 /* Convert value RHS to type TYPE as preparation for an assignment
4061    to an lvalue of type TYPE.
4062    The real work of conversion is done by `convert'.
4063    The purpose of this function is to generate error messages
4064    for assignments that are not allowed in C.
4065    ERRTYPE is a string to use in error messages:
4066    "assignment", "return", etc.  If it is null, this is parameter passing
4067    for a function call (and different error messages are output).
4068
4069    FUNNAME is the name of the function being called,
4070    as an IDENTIFIER_NODE, or null.
4071    PARMNUM is the number of the argument, for printing in error messages.  */
4072
4073 static tree
4074 convert_for_assignment (type, rhs, errtype, fundecl, funname, parmnum)
4075      tree type, rhs;
4076      const char *errtype;
4077      tree fundecl, funname;
4078      int parmnum;
4079 {
4080   register enum tree_code codel = TREE_CODE (type);
4081   register tree rhstype;
4082   register enum tree_code coder;
4083
4084   /* Strip NON_LVALUE_EXPRs since we aren't using as an lvalue.  */
4085   /* Do not use STRIP_NOPS here.  We do not want an enumerator
4086      whose value is 0 to count as a null pointer constant.  */
4087   if (TREE_CODE (rhs) == NON_LVALUE_EXPR)
4088     rhs = TREE_OPERAND (rhs, 0);
4089
4090   if (TREE_CODE (TREE_TYPE (rhs)) == ARRAY_TYPE
4091       || TREE_CODE (TREE_TYPE (rhs)) == FUNCTION_TYPE)
4092     rhs = default_conversion (rhs);
4093   else if (optimize && TREE_CODE (rhs) == VAR_DECL)
4094     rhs = decl_constant_value_for_broken_optimization (rhs);
4095
4096   rhstype = TREE_TYPE (rhs);
4097   coder = TREE_CODE (rhstype);
4098
4099   if (coder == ERROR_MARK)
4100     return error_mark_node;
4101
4102   if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (rhstype))
4103     {
4104       overflow_warning (rhs);
4105       /* Check for Objective-C protocols.  This will issue a warning if
4106          there are protocol violations.  No need to use the return value.  */
4107       maybe_objc_comptypes (type, rhstype, 0);
4108       return rhs;
4109     }
4110
4111   if (coder == VOID_TYPE)
4112     {
4113       error ("void value not ignored as it ought to be");
4114       return error_mark_node;
4115     }
4116   /* A type converts to a reference to it.
4117      This code doesn't fully support references, it's just for the
4118      special case of va_start and va_copy.  */
4119   if (codel == REFERENCE_TYPE
4120       && comptypes (TREE_TYPE (type), TREE_TYPE (rhs)) == 1)
4121     {
4122       if (mark_addressable (rhs) == 0)
4123         return error_mark_node;
4124       rhs = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (rhs)), rhs);
4125
4126       /* We already know that these two types are compatible, but they
4127          may not be exactly identical.  In fact, `TREE_TYPE (type)' is
4128          likely to be __builtin_va_list and `TREE_TYPE (rhs)' is
4129          likely to be va_list, a typedef to __builtin_va_list, which
4130          is different enough that it will cause problems later.  */
4131       if (TREE_TYPE (TREE_TYPE (rhs)) != TREE_TYPE (type))
4132         rhs = build1 (NOP_EXPR, build_pointer_type (TREE_TYPE (type)), rhs);
4133
4134       rhs = build1 (NOP_EXPR, type, rhs);
4135       return rhs;
4136     }
4137   /* Arithmetic types all interconvert, and enum is treated like int.  */
4138   else if ((codel == INTEGER_TYPE || codel == REAL_TYPE
4139             || codel == ENUMERAL_TYPE || codel == COMPLEX_TYPE
4140             || codel == BOOLEAN_TYPE)
4141            && (coder == INTEGER_TYPE || coder == REAL_TYPE
4142                || coder == ENUMERAL_TYPE || coder == COMPLEX_TYPE
4143                || coder == BOOLEAN_TYPE))
4144     return convert_and_check (type, rhs);
4145
4146   /* Conversion to a transparent union from its member types.
4147      This applies only to function arguments.  */
4148   else if (codel == UNION_TYPE && TYPE_TRANSPARENT_UNION (type) && ! errtype)
4149     {
4150       tree memb_types;
4151       tree marginal_memb_type = 0;
4152
4153       for (memb_types = TYPE_FIELDS (type); memb_types;
4154            memb_types = TREE_CHAIN (memb_types))
4155         {
4156           tree memb_type = TREE_TYPE (memb_types);
4157
4158           if (comptypes (TYPE_MAIN_VARIANT (memb_type),
4159                          TYPE_MAIN_VARIANT (rhstype)))
4160             break;
4161
4162           if (TREE_CODE (memb_type) != POINTER_TYPE)
4163             continue;
4164
4165           if (coder == POINTER_TYPE)
4166             {
4167               register tree ttl = TREE_TYPE (memb_type);
4168               register tree ttr = TREE_TYPE (rhstype);
4169
4170               /* Any non-function converts to a [const][volatile] void *
4171                  and vice versa; otherwise, targets must be the same.
4172                  Meanwhile, the lhs target must have all the qualifiers of
4173                  the rhs.  */
4174               if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
4175                   || comp_target_types (memb_type, rhstype))
4176                 {
4177                   /* If this type won't generate any warnings, use it.  */
4178                   if (TYPE_QUALS (ttl) == TYPE_QUALS (ttr)
4179                       || ((TREE_CODE (ttr) == FUNCTION_TYPE
4180                            && TREE_CODE (ttl) == FUNCTION_TYPE)
4181                           ? ((TYPE_QUALS (ttl) | TYPE_QUALS (ttr))
4182                              == TYPE_QUALS (ttr))
4183                           : ((TYPE_QUALS (ttl) | TYPE_QUALS (ttr))
4184                              == TYPE_QUALS (ttl))))
4185                     break;
4186
4187                   /* Keep looking for a better type, but remember this one.  */
4188                   if (! marginal_memb_type)
4189                     marginal_memb_type = memb_type;
4190                 }
4191             }
4192
4193           /* Can convert integer zero to any pointer type.  */
4194           if (integer_zerop (rhs)
4195               || (TREE_CODE (rhs) == NOP_EXPR
4196                   && integer_zerop (TREE_OPERAND (rhs, 0))))
4197             {
4198               rhs = null_pointer_node;
4199               break;
4200             }
4201         }
4202
4203       if (memb_types || marginal_memb_type)
4204         {
4205           if (! memb_types)
4206             {
4207               /* We have only a marginally acceptable member type;
4208                  it needs a warning.  */
4209               register tree ttl = TREE_TYPE (marginal_memb_type);
4210               register tree ttr = TREE_TYPE (rhstype);
4211
4212               /* Const and volatile mean something different for function
4213                  types, so the usual warnings are not appropriate.  */
4214               if (TREE_CODE (ttr) == FUNCTION_TYPE
4215                   && TREE_CODE (ttl) == FUNCTION_TYPE)
4216                 {
4217                   /* Because const and volatile on functions are
4218                      restrictions that say the function will not do
4219                      certain things, it is okay to use a const or volatile
4220                      function where an ordinary one is wanted, but not
4221                      vice-versa.  */
4222                   if (TYPE_QUALS (ttl) & ~TYPE_QUALS (ttr))
4223                     warn_for_assignment ("%s makes qualified function pointer from unqualified",
4224                                          errtype, funname, parmnum);
4225                 }
4226               else if (TYPE_QUALS (ttr) & ~TYPE_QUALS (ttl))
4227                 warn_for_assignment ("%s discards qualifiers from pointer target type",
4228                                      errtype, funname,
4229                                      parmnum);
4230             }
4231
4232           if (pedantic && ! DECL_IN_SYSTEM_HEADER (fundecl))
4233             pedwarn ("ISO C prohibits argument conversion to union type");
4234
4235           return build1 (NOP_EXPR, type, rhs);
4236         }
4237     }
4238
4239   /* Conversions among pointers */
4240   else if ((codel == POINTER_TYPE || codel == REFERENCE_TYPE)
4241            && (coder == POINTER_TYPE || coder == REFERENCE_TYPE))
4242     {
4243       register tree ttl = TREE_TYPE (type);
4244       register tree ttr = TREE_TYPE (rhstype);
4245
4246       /* Any non-function converts to a [const][volatile] void *
4247          and vice versa; otherwise, targets must be the same.
4248          Meanwhile, the lhs target must have all the qualifiers of the rhs.  */
4249       if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
4250           || comp_target_types (type, rhstype)
4251           || (unsigned_type (TYPE_MAIN_VARIANT (ttl))
4252               == unsigned_type (TYPE_MAIN_VARIANT (ttr))))
4253         {
4254           if (pedantic
4255               && ((VOID_TYPE_P (ttl) && TREE_CODE (ttr) == FUNCTION_TYPE)
4256                   ||
4257                   (VOID_TYPE_P (ttr)
4258                    /* Check TREE_CODE to catch cases like (void *) (char *) 0
4259                       which are not ANSI null ptr constants.  */
4260                    && (!integer_zerop (rhs) || TREE_CODE (rhs) == NOP_EXPR)
4261                    && TREE_CODE (ttl) == FUNCTION_TYPE)))
4262             warn_for_assignment ("ISO C forbids %s between function pointer and `void *'",
4263                                  errtype, funname, parmnum);
4264           /* Const and volatile mean something different for function types,
4265              so the usual warnings are not appropriate.  */
4266           else if (TREE_CODE (ttr) != FUNCTION_TYPE
4267                    && TREE_CODE (ttl) != FUNCTION_TYPE)
4268             {
4269               if (TYPE_QUALS (ttr) & ~TYPE_QUALS (ttl))
4270                 warn_for_assignment ("%s discards qualifiers from pointer target type",
4271                                      errtype, funname, parmnum);
4272               /* If this is not a case of ignoring a mismatch in signedness,
4273                  no warning.  */
4274               else if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
4275                        || comp_target_types (type, rhstype))
4276                 ;
4277               /* If there is a mismatch, do warn.  */
4278               else if (pedantic)
4279                 warn_for_assignment ("pointer targets in %s differ in signedness",
4280                                      errtype, funname, parmnum);
4281             }
4282           else if (TREE_CODE (ttl) == FUNCTION_TYPE
4283                    && TREE_CODE (ttr) == FUNCTION_TYPE)
4284             {
4285               /* Because const and volatile on functions are restrictions
4286                  that say the function will not do certain things,
4287                  it is okay to use a const or volatile function
4288                  where an ordinary one is wanted, but not vice-versa.  */
4289               if (TYPE_QUALS (ttl) & ~TYPE_QUALS (ttr))
4290                 warn_for_assignment ("%s makes qualified function pointer from unqualified",
4291                                      errtype, funname, parmnum);
4292             }
4293         }
4294       else
4295         warn_for_assignment ("%s from incompatible pointer type",
4296                              errtype, funname, parmnum);
4297       return convert (type, rhs);
4298     }
4299   else if (codel == POINTER_TYPE && coder == INTEGER_TYPE)
4300     {
4301       /* An explicit constant 0 can convert to a pointer,
4302          or one that results from arithmetic, even including
4303          a cast to integer type.  */
4304       if (! (TREE_CODE (rhs) == INTEGER_CST && integer_zerop (rhs))
4305           &&
4306           ! (TREE_CODE (rhs) == NOP_EXPR
4307              && TREE_CODE (TREE_TYPE (rhs)) == INTEGER_TYPE
4308              && TREE_CODE (TREE_OPERAND (rhs, 0)) == INTEGER_CST
4309              && integer_zerop (TREE_OPERAND (rhs, 0))))
4310         {
4311           warn_for_assignment ("%s makes pointer from integer without a cast",
4312                                errtype, funname, parmnum);
4313           return convert (type, rhs);
4314         }
4315       return null_pointer_node;
4316     }
4317   else if (codel == INTEGER_TYPE && coder == POINTER_TYPE)
4318     {
4319       warn_for_assignment ("%s makes integer from pointer without a cast",
4320                            errtype, funname, parmnum);
4321       return convert (type, rhs);
4322     }
4323   else if (codel == BOOLEAN_TYPE && coder == POINTER_TYPE)
4324     return convert (type, rhs);
4325
4326   if (!errtype)
4327     {
4328       if (funname)
4329         {
4330           tree selector = maybe_building_objc_message_expr ();
4331
4332           if (selector && parmnum > 2)
4333             error ("incompatible type for argument %d of `%s'",
4334                    parmnum - 2, IDENTIFIER_POINTER (selector));
4335           else
4336             error ("incompatible type for argument %d of `%s'",
4337                    parmnum, IDENTIFIER_POINTER (funname));
4338         }
4339       else
4340         error ("incompatible type for argument %d of indirect function call",
4341                parmnum);
4342     }
4343   else
4344     error ("incompatible types in %s", errtype);
4345
4346   return error_mark_node;
4347 }
4348
4349 /* Print a warning using MSGID.
4350    It gets OPNAME as its one parameter.
4351    If OPNAME is null, it is replaced by "passing arg ARGNUM of `FUNCTION'".
4352    FUNCTION and ARGNUM are handled specially if we are building an
4353    Objective-C selector.  */
4354
4355 static void
4356 warn_for_assignment (msgid, opname, function, argnum)
4357      const char *msgid;
4358      const char *opname;
4359      tree function;
4360      int argnum;
4361 {
4362   if (opname == 0)
4363     {
4364       tree selector = maybe_building_objc_message_expr ();
4365       char * new_opname;
4366
4367       if (selector && argnum > 2)
4368         {
4369           function = selector;
4370           argnum -= 2;
4371         }
4372       if (function)
4373         {
4374           /* Function name is known; supply it.  */
4375           const char *argstring = _("passing arg %d of `%s'");
4376           new_opname = (char *) alloca (IDENTIFIER_LENGTH (function)
4377                                         + strlen (argstring) + 1 + 25
4378                                         /*%d*/ + 1);
4379           sprintf (new_opname, argstring, argnum,
4380                    IDENTIFIER_POINTER (function));
4381         }
4382       else
4383         {
4384           /* Function name unknown (call through ptr); just give arg number.*/
4385           const char *argnofun = _("passing arg %d of pointer to function");
4386           new_opname = (char *) alloca (strlen (argnofun) + 1 + 25 /*%d*/ + 1);
4387           sprintf (new_opname, argnofun, argnum);
4388         }
4389       opname = new_opname;
4390     }
4391   pedwarn (msgid, opname);
4392 }
4393 \f
4394 /* If VALUE is a compound expr all of whose expressions are constant, then
4395    return its value.  Otherwise, return error_mark_node.
4396
4397    This is for handling COMPOUND_EXPRs as initializer elements
4398    which is allowed with a warning when -pedantic is specified.  */
4399
4400 static tree
4401 valid_compound_expr_initializer (value, endtype)
4402      tree value;
4403      tree endtype;
4404 {
4405   if (TREE_CODE (value) == COMPOUND_EXPR)
4406     {
4407       if (valid_compound_expr_initializer (TREE_OPERAND (value, 0), endtype)
4408           == error_mark_node)
4409         return error_mark_node;
4410       return valid_compound_expr_initializer (TREE_OPERAND (value, 1),
4411                                               endtype);
4412     }
4413   else if (! TREE_CONSTANT (value)
4414            && ! initializer_constant_valid_p (value, endtype))
4415     return error_mark_node;
4416   else
4417     return value;
4418 }
4419 \f
4420 /* Perform appropriate conversions on the initial value of a variable,
4421    store it in the declaration DECL,
4422    and print any error messages that are appropriate.
4423    If the init is invalid, store an ERROR_MARK.  */
4424
4425 void
4426 store_init_value (decl, init)
4427      tree decl, init;
4428 {
4429   register tree value, type;
4430
4431   /* If variable's type was invalidly declared, just ignore it.  */
4432
4433   type = TREE_TYPE (decl);
4434   if (TREE_CODE (type) == ERROR_MARK)
4435     return;
4436
4437   /* Digest the specified initializer into an expression.  */
4438
4439   value = digest_init (type, init, TREE_STATIC (decl),
4440                        TREE_STATIC (decl) || (pedantic && !flag_isoc99));
4441
4442   /* Store the expression if valid; else report error.  */
4443
4444 #if 0
4445   /* Note that this is the only place we can detect the error
4446      in a case such as   struct foo bar = (struct foo) { x, y };
4447      where there is one initial value which is a constructor expression.  */
4448   if (value == error_mark_node)
4449     ;
4450   else if (TREE_STATIC (decl) && ! TREE_CONSTANT (value))
4451     {
4452       error ("initializer for static variable is not constant");
4453       value = error_mark_node;
4454     }
4455   else if (TREE_STATIC (decl)
4456            && initializer_constant_valid_p (value, TREE_TYPE (value)) == 0)
4457     {
4458       error ("initializer for static variable uses complicated arithmetic");
4459       value = error_mark_node;
4460     }
4461   else
4462     {
4463       if (pedantic && TREE_CODE (value) == CONSTRUCTOR)
4464         {
4465           if (! TREE_CONSTANT (value))
4466             pedwarn ("aggregate initializer is not constant");
4467           else if (! TREE_STATIC (value))
4468             pedwarn ("aggregate initializer uses complicated arithmetic");
4469         }
4470     }
4471 #endif
4472
4473   if (warn_traditional && !in_system_header
4474       && AGGREGATE_TYPE_P (TREE_TYPE (decl)) && ! TREE_STATIC (decl))
4475     warning ("traditional C rejects automatic aggregate initialization");
4476
4477   DECL_INITIAL (decl) = value;
4478
4479   /* ANSI wants warnings about out-of-range constant initializers.  */
4480   STRIP_TYPE_NOPS (value);
4481   constant_expression_warning (value);
4482 }
4483 \f
4484 /* Methods for storing and printing names for error messages.  */
4485
4486 /* Implement a spelling stack that allows components of a name to be pushed
4487    and popped.  Each element on the stack is this structure.  */
4488
4489 struct spelling
4490 {
4491   int kind;
4492   union
4493     {
4494       int i;
4495       const char *s;
4496     } u;
4497 };
4498
4499 #define SPELLING_STRING 1
4500 #define SPELLING_MEMBER 2
4501 #define SPELLING_BOUNDS 3
4502
4503 static struct spelling *spelling;       /* Next stack element (unused).  */
4504 static struct spelling *spelling_base;  /* Spelling stack base.  */
4505 static int spelling_size;               /* Size of the spelling stack.  */
4506
4507 /* Macros to save and restore the spelling stack around push_... functions.
4508    Alternative to SAVE_SPELLING_STACK.  */
4509
4510 #define SPELLING_DEPTH() (spelling - spelling_base)
4511 #define RESTORE_SPELLING_DEPTH(depth) (spelling = spelling_base + depth)
4512
4513 /* Save and restore the spelling stack around arbitrary C code.  */
4514
4515 #define SAVE_SPELLING_DEPTH(code)               \
4516 {                                               \
4517   int __depth = SPELLING_DEPTH ();              \
4518   code;                                         \
4519   RESTORE_SPELLING_DEPTH (__depth);             \
4520 }
4521
4522 /* Push an element on the spelling stack with type KIND and assign VALUE
4523    to MEMBER.  */
4524
4525 #define PUSH_SPELLING(KIND, VALUE, MEMBER)                              \
4526 {                                                                       \
4527   int depth = SPELLING_DEPTH ();                                        \
4528                                                                         \
4529   if (depth >= spelling_size)                                           \
4530     {                                                                   \
4531       spelling_size += 10;                                              \
4532       if (spelling_base == 0)                                           \
4533         spelling_base                                                   \
4534           = (struct spelling *) xmalloc (spelling_size * sizeof (struct spelling));     \
4535       else                                                              \
4536         spelling_base                                                   \
4537           = (struct spelling *) xrealloc (spelling_base,                \
4538                                           spelling_size * sizeof (struct spelling));    \
4539       RESTORE_SPELLING_DEPTH (depth);                                   \
4540     }                                                                   \
4541                                                                         \
4542   spelling->kind = (KIND);                                              \
4543   spelling->MEMBER = (VALUE);                                           \
4544   spelling++;                                                           \
4545 }
4546
4547 /* Push STRING on the stack.  Printed literally.  */
4548
4549 static void
4550 push_string (string)
4551      const char *string;
4552 {
4553   PUSH_SPELLING (SPELLING_STRING, string, u.s);
4554 }
4555
4556 /* Push a member name on the stack.  Printed as '.' STRING.  */
4557
4558 static void
4559 push_member_name (decl)
4560      tree decl;
4561
4562 {
4563   const char *string
4564     = DECL_NAME (decl) ? IDENTIFIER_POINTER (DECL_NAME (decl)) : "<anonymous>";
4565   PUSH_SPELLING (SPELLING_MEMBER, string, u.s);
4566 }
4567
4568 /* Push an array bounds on the stack.  Printed as [BOUNDS].  */
4569
4570 static void
4571 push_array_bounds (bounds)
4572      int bounds;
4573 {
4574   PUSH_SPELLING (SPELLING_BOUNDS, bounds, u.i);
4575 }
4576
4577 /* Compute the maximum size in bytes of the printed spelling.  */
4578
4579 static int
4580 spelling_length ()
4581 {
4582   register int size = 0;
4583   register struct spelling *p;
4584
4585   for (p = spelling_base; p < spelling; p++)
4586     {
4587       if (p->kind == SPELLING_BOUNDS)
4588         size += 25;
4589       else
4590         size += strlen (p->u.s) + 1;
4591     }
4592
4593   return size;
4594 }
4595
4596 /* Print the spelling to BUFFER and return it.  */
4597
4598 static char *
4599 print_spelling (buffer)
4600      register char *buffer;
4601 {
4602   register char *d = buffer;
4603   register struct spelling *p;
4604
4605   for (p = spelling_base; p < spelling; p++)
4606     if (p->kind == SPELLING_BOUNDS)
4607       {
4608         sprintf (d, "[%d]", p->u.i);
4609         d += strlen (d);
4610       }
4611     else
4612       {
4613         register const char *s;
4614         if (p->kind == SPELLING_MEMBER)
4615           *d++ = '.';
4616         for (s = p->u.s; (*d = *s++); d++)
4617           ;
4618       }
4619   *d++ = '\0';
4620   return buffer;
4621 }
4622
4623 /* Issue an error message for a bad initializer component.
4624    MSGID identifies the message.
4625    The component name is taken from the spelling stack.  */
4626
4627 void
4628 error_init (msgid)
4629      const char *msgid;
4630 {
4631   char *ofwhat;
4632
4633   error ("%s", msgid);
4634   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4635   if (*ofwhat)
4636     error ("(near initialization for `%s')", ofwhat);
4637 }
4638
4639 /* Issue a pedantic warning for a bad initializer component.
4640    MSGID identifies the message.
4641    The component name is taken from the spelling stack.  */
4642
4643 void
4644 pedwarn_init (msgid)
4645      const char *msgid;
4646 {
4647   char *ofwhat;
4648
4649   pedwarn ("%s", msgid);
4650   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4651   if (*ofwhat)
4652     pedwarn ("(near initialization for `%s')", ofwhat);
4653 }
4654
4655 /* Issue a warning for a bad initializer component.
4656    MSGID identifies the message.
4657    The component name is taken from the spelling stack.  */
4658
4659 static void
4660 warning_init (msgid)
4661      const char *msgid;
4662 {
4663   char *ofwhat;
4664
4665   warning ("%s", msgid);
4666   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4667   if (*ofwhat)
4668     warning ("(near initialization for `%s')", ofwhat);
4669 }
4670 \f
4671 /* Digest the parser output INIT as an initializer for type TYPE.
4672    Return a C expression of type TYPE to represent the initial value.
4673
4674    The arguments REQUIRE_CONSTANT and CONSTRUCTOR_CONSTANT request errors
4675    if non-constant initializers or elements are seen.  CONSTRUCTOR_CONSTANT
4676    applies only to elements of constructors.  */
4677
4678 static tree
4679 digest_init (type, init, require_constant, constructor_constant)
4680      tree type, init;
4681      int require_constant, constructor_constant;
4682 {
4683   enum tree_code code = TREE_CODE (type);
4684   tree inside_init = init;
4685
4686   if (type == error_mark_node
4687       || init == error_mark_node
4688       || TREE_TYPE (init)  == error_mark_node)
4689     return error_mark_node;
4690
4691   /* Strip NON_LVALUE_EXPRs since we aren't using as an lvalue.  */
4692   /* Do not use STRIP_NOPS here.  We do not want an enumerator
4693      whose value is 0 to count as a null pointer constant.  */
4694   if (TREE_CODE (init) == NON_LVALUE_EXPR)
4695     inside_init = TREE_OPERAND (init, 0);
4696
4697   inside_init = fold (inside_init);
4698
4699   /* Initialization of an array of chars from a string constant
4700      optionally enclosed in braces.  */
4701
4702   if (code == ARRAY_TYPE)
4703     {
4704       tree typ1 = TYPE_MAIN_VARIANT (TREE_TYPE (type));
4705       if ((typ1 == char_type_node
4706            || typ1 == signed_char_type_node
4707            || typ1 == unsigned_char_type_node
4708            || typ1 == unsigned_wchar_type_node
4709            || typ1 == signed_wchar_type_node)
4710           && ((inside_init && TREE_CODE (inside_init) == STRING_CST)))
4711         {
4712           if (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4713                          TYPE_MAIN_VARIANT (type)))
4714             return inside_init;
4715
4716           if ((TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (inside_init)))
4717                != char_type_node)
4718               && TYPE_PRECISION (typ1) == TYPE_PRECISION (char_type_node))
4719             {
4720               error_init ("char-array initialized from wide string");
4721               return error_mark_node;
4722             }
4723           if ((TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (inside_init)))
4724                == char_type_node)
4725               && TYPE_PRECISION (typ1) != TYPE_PRECISION (char_type_node))
4726             {
4727               error_init ("int-array initialized from non-wide string");
4728               return error_mark_node;
4729             }
4730
4731           TREE_TYPE (inside_init) = type;
4732           if (TYPE_DOMAIN (type) != 0
4733               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
4734               /* Subtract 1 (or sizeof (wchar_t))
4735                  because it's ok to ignore the terminating null char
4736                  that is counted in the length of the constant.  */
4737               && 0 > compare_tree_int (TYPE_SIZE_UNIT (type),
4738                                        TREE_STRING_LENGTH (inside_init)
4739                                        - ((TYPE_PRECISION (typ1)
4740                                            != TYPE_PRECISION (char_type_node))
4741                                           ? (TYPE_PRECISION (wchar_type_node)
4742                                              / BITS_PER_UNIT)
4743                                           : 1)))
4744             pedwarn_init ("initializer-string for array of chars is too long");
4745
4746           return inside_init;
4747         }
4748     }
4749
4750   /* Any type can be initialized
4751      from an expression of the same type, optionally with braces.  */
4752
4753   if (inside_init && TREE_TYPE (inside_init) != 0
4754       && (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4755                      TYPE_MAIN_VARIANT (type))
4756           || (code == ARRAY_TYPE
4757               && comptypes (TREE_TYPE (inside_init), type))
4758           || (code == POINTER_TYPE
4759               && (TREE_CODE (TREE_TYPE (inside_init)) == ARRAY_TYPE
4760                   || TREE_CODE (TREE_TYPE (inside_init)) == FUNCTION_TYPE)
4761               && comptypes (TREE_TYPE (TREE_TYPE (inside_init)),
4762                             TREE_TYPE (type)))))
4763     {
4764       if (code == POINTER_TYPE
4765           && (TREE_CODE (TREE_TYPE (inside_init)) == ARRAY_TYPE
4766               || TREE_CODE (TREE_TYPE (inside_init)) == FUNCTION_TYPE))
4767         inside_init = default_conversion (inside_init);
4768       else if (code == ARRAY_TYPE && TREE_CODE (inside_init) != STRING_CST
4769                && TREE_CODE (inside_init) != CONSTRUCTOR)
4770         {
4771           error_init ("array initialized from non-constant array expression");
4772           return error_mark_node;
4773         }
4774
4775       if (optimize && TREE_CODE (inside_init) == VAR_DECL)
4776         inside_init = decl_constant_value_for_broken_optimization (inside_init);
4777
4778       /* Compound expressions can only occur here if -pedantic or
4779          -pedantic-errors is specified.  In the later case, we always want
4780          an error.  In the former case, we simply want a warning.  */
4781       if (require_constant && pedantic
4782           && TREE_CODE (inside_init) == COMPOUND_EXPR)
4783         {
4784           inside_init
4785             = valid_compound_expr_initializer (inside_init,
4786                                                TREE_TYPE (inside_init));
4787           if (inside_init == error_mark_node)
4788             error_init ("initializer element is not constant");
4789           else
4790             pedwarn_init ("initializer element is not constant");
4791           if (flag_pedantic_errors)
4792             inside_init = error_mark_node;
4793         }
4794       else if (require_constant
4795                && (!TREE_CONSTANT (inside_init)
4796                    /* This test catches things like `7 / 0' which
4797                       result in an expression for which TREE_CONSTANT
4798                       is true, but which is not actually something
4799                       that is a legal constant.  We really should not
4800                       be using this function, because it is a part of
4801                       the back-end.  Instead, the expression should
4802                       already have been turned into ERROR_MARK_NODE.  */
4803                    || !initializer_constant_valid_p (inside_init,
4804                                                      TREE_TYPE (inside_init))))
4805         {
4806           error_init ("initializer element is not constant");
4807           inside_init = error_mark_node;
4808         }
4809
4810       return inside_init;
4811     }
4812
4813   /* Handle scalar types, including conversions.  */
4814
4815   if (code == INTEGER_TYPE || code == REAL_TYPE || code == POINTER_TYPE
4816       || code == ENUMERAL_TYPE || code == BOOLEAN_TYPE || code == COMPLEX_TYPE)
4817     {
4818       /* Note that convert_for_assignment calls default_conversion
4819          for arrays and functions.  We must not call it in the
4820          case where inside_init is a null pointer constant.  */
4821       inside_init
4822         = convert_for_assignment (type, init, _("initialization"),
4823                                   NULL_TREE, NULL_TREE, 0);
4824
4825       if (require_constant && ! TREE_CONSTANT (inside_init))
4826         {
4827           error_init ("initializer element is not constant");
4828           inside_init = error_mark_node;
4829         }
4830       else if (require_constant
4831                && initializer_constant_valid_p (inside_init, TREE_TYPE (inside_init)) == 0)
4832         {
4833           error_init ("initializer element is not computable at load time");
4834           inside_init = error_mark_node;
4835         }
4836
4837       return inside_init;
4838     }
4839
4840   /* Come here only for records and arrays.  */
4841
4842   if (COMPLETE_TYPE_P (type) && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
4843     {
4844       error_init ("variable-sized object may not be initialized");
4845       return error_mark_node;
4846     }
4847
4848   /* Traditionally, you can write  struct foo x = 0;
4849      and it initializes the first element of x to 0.  */
4850   if (flag_traditional)
4851     {
4852       tree top = 0, prev = 0, otype = type;
4853       while (TREE_CODE (type) == RECORD_TYPE
4854              || TREE_CODE (type) == ARRAY_TYPE
4855              || TREE_CODE (type) == QUAL_UNION_TYPE
4856              || TREE_CODE (type) == UNION_TYPE)
4857         {
4858           tree temp = build (CONSTRUCTOR, type, NULL_TREE, NULL_TREE);
4859           if (prev == 0)
4860             top = temp;
4861           else
4862             TREE_OPERAND (prev, 1) = build_tree_list (NULL_TREE, temp);
4863           prev = temp;
4864           if (TREE_CODE (type) == ARRAY_TYPE)
4865             type = TREE_TYPE (type);
4866           else if (TYPE_FIELDS (type))
4867             type = TREE_TYPE (TYPE_FIELDS (type));
4868           else
4869             {
4870               error_init ("invalid initializer");
4871               return error_mark_node;
4872             }
4873         }
4874
4875       if (otype != type)
4876         {
4877           TREE_OPERAND (prev, 1)
4878             = build_tree_list (NULL_TREE,
4879                                digest_init (type, init, require_constant,
4880                                             constructor_constant));
4881           return top;
4882         }
4883       else
4884         return error_mark_node;
4885     }
4886   error_init ("invalid initializer");
4887   return error_mark_node;
4888 }
4889 \f
4890 /* Handle initializers that use braces.  */
4891
4892 /* Type of object we are accumulating a constructor for.
4893    This type is always a RECORD_TYPE, UNION_TYPE or ARRAY_TYPE.  */
4894 static tree constructor_type;
4895
4896 /* For a RECORD_TYPE or UNION_TYPE, this is the chain of fields
4897    left to fill.  */
4898 static tree constructor_fields;
4899
4900 /* For an ARRAY_TYPE, this is the specified index
4901    at which to store the next element we get.  */
4902 static tree constructor_index;
4903
4904 /* For an ARRAY_TYPE, this is the maximum index.  */
4905 static tree constructor_max_index;
4906
4907 /* For a RECORD_TYPE, this is the first field not yet written out.  */
4908 static tree constructor_unfilled_fields;
4909
4910 /* For an ARRAY_TYPE, this is the index of the first element
4911    not yet written out.  */
4912 static tree constructor_unfilled_index;
4913
4914 /* In a RECORD_TYPE, the byte index of the next consecutive field.
4915    This is so we can generate gaps between fields, when appropriate.  */
4916 static tree constructor_bit_index;
4917
4918 /* If we are saving up the elements rather than allocating them,
4919    this is the list of elements so far (in reverse order,
4920    most recent first).  */
4921 static tree constructor_elements;
4922
4923 /* 1 if constructor should be incrementally stored into a constructor chain,
4924    0 if all the elements should be kept in AVL tree.  */
4925 static int constructor_incremental;
4926
4927 /* 1 if so far this constructor's elements are all compile-time constants.  */
4928 static int constructor_constant;
4929
4930 /* 1 if so far this constructor's elements are all valid address constants.  */
4931 static int constructor_simple;
4932
4933 /* 1 if this constructor is erroneous so far.  */
4934 static int constructor_erroneous;
4935
4936 /* 1 if have called defer_addressed_constants.  */
4937 static int constructor_subconstants_deferred;
4938
4939 /* Structure for managing pending initializer elements, organized as an
4940    AVL tree.  */
4941
4942 struct init_node
4943 {
4944   struct init_node *left, *right;
4945   struct init_node *parent;
4946   int balance;
4947   tree purpose;
4948   tree value;
4949 };
4950
4951 /* Tree of pending elements at this constructor level.
4952    These are elements encountered out of order
4953    which belong at places we haven't reached yet in actually
4954    writing the output.
4955    Will never hold tree nodes across GC runs.  */
4956 static struct init_node *constructor_pending_elts;
4957
4958 /* The SPELLING_DEPTH of this constructor.  */
4959 static int constructor_depth;
4960
4961 /* 0 if implicitly pushing constructor levels is allowed.  */
4962 int constructor_no_implicit = 0; /* 0 for C; 1 for some other languages.  */
4963
4964 static int require_constant_value;
4965 static int require_constant_elements;
4966
4967 /* DECL node for which an initializer is being read.
4968    0 means we are reading a constructor expression
4969    such as (struct foo) {...}.  */
4970 static tree constructor_decl;
4971
4972 /* start_init saves the ASMSPEC arg here for really_start_incremental_init.  */
4973 static const char *constructor_asmspec;
4974
4975 /* Nonzero if this is an initializer for a top-level decl.  */
4976 static int constructor_top_level;
4977
4978 /* Nesting depth of designator list.  */
4979 static int designator_depth;
4980
4981 /* Nonzero if there were diagnosed errors in this designator list.  */
4982 static int designator_errorneous;
4983
4984 \f
4985 /* This stack has a level for each implicit or explicit level of
4986    structuring in the initializer, including the outermost one.  It
4987    saves the values of most of the variables above.  */
4988
4989 struct constructor_range_stack;
4990
4991 struct constructor_stack
4992 {
4993   struct constructor_stack *next;
4994   tree type;
4995   tree fields;
4996   tree index;
4997   tree max_index;
4998   tree unfilled_index;
4999   tree unfilled_fields;
5000   tree bit_index;
5001   tree elements;
5002   struct init_node *pending_elts;
5003   int offset;
5004   int depth;
5005   /* If nonzero, this value should replace the entire
5006      constructor at this level.  */
5007   tree replacement_value;
5008   struct constructor_range_stack *range_stack;
5009   char constant;
5010   char simple;
5011   char implicit;
5012   char erroneous;
5013   char outer;
5014   char incremental;
5015 };
5016
5017 struct constructor_stack *constructor_stack;
5018
5019 /* This stack represents designators from some range designator up to
5020    the last designator in the list.  */
5021
5022 struct constructor_range_stack
5023 {
5024   struct constructor_range_stack *next, *prev;
5025   struct constructor_stack *stack;
5026   tree range_start;
5027   tree index;
5028   tree range_end;
5029   tree fields;
5030 };
5031
5032 struct constructor_range_stack *constructor_range_stack;
5033
5034 /* This stack records separate initializers that are nested.
5035    Nested initializers can't happen in ANSI C, but GNU C allows them
5036    in cases like { ... (struct foo) { ... } ... }.  */
5037
5038 struct initializer_stack
5039 {
5040   struct initializer_stack *next;
5041   tree decl;
5042   const char *asmspec;
5043   struct constructor_stack *constructor_stack;
5044   struct constructor_range_stack *constructor_range_stack;
5045   tree elements;
5046   struct spelling *spelling;
5047   struct spelling *spelling_base;
5048   int spelling_size;
5049   char top_level;
5050   char require_constant_value;
5051   char require_constant_elements;
5052   char deferred;
5053 };
5054
5055 struct initializer_stack *initializer_stack;
5056 \f
5057 /* Prepare to parse and output the initializer for variable DECL.  */
5058
5059 void
5060 start_init (decl, asmspec_tree, top_level)
5061      tree decl;
5062      tree asmspec_tree;
5063      int top_level;
5064 {
5065   const char *locus;
5066   struct initializer_stack *p
5067     = (struct initializer_stack *) xmalloc (sizeof (struct initializer_stack));
5068   const char *asmspec = 0;
5069
5070   if (asmspec_tree)
5071     asmspec = TREE_STRING_POINTER (asmspec_tree);
5072
5073   p->decl = constructor_decl;
5074   p->asmspec = constructor_asmspec;
5075   p->require_constant_value = require_constant_value;
5076   p->require_constant_elements = require_constant_elements;
5077   p->constructor_stack = constructor_stack;
5078   p->constructor_range_stack = constructor_range_stack;
5079   p->elements = constructor_elements;
5080   p->spelling = spelling;
5081   p->spelling_base = spelling_base;
5082   p->spelling_size = spelling_size;
5083   p->deferred = constructor_subconstants_deferred;
5084   p->top_level = constructor_top_level;
5085   p->next = initializer_stack;
5086   initializer_stack = p;
5087
5088   constructor_decl = decl;
5089   constructor_asmspec = asmspec;
5090   constructor_subconstants_deferred = 0;
5091   constructor_top_level = top_level;
5092
5093   if (decl != 0)
5094     {
5095       require_constant_value = TREE_STATIC (decl);
5096       require_constant_elements
5097         = ((TREE_STATIC (decl) || (pedantic && !flag_isoc99))
5098            /* For a scalar, you can always use any value to initialize,
5099               even within braces.  */
5100            && (TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE
5101                || TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
5102                || TREE_CODE (TREE_TYPE (decl)) == UNION_TYPE
5103                || TREE_CODE (TREE_TYPE (decl)) == QUAL_UNION_TYPE));
5104       locus = IDENTIFIER_POINTER (DECL_NAME (decl));
5105     }
5106   else
5107     {
5108       require_constant_value = 0;
5109       require_constant_elements = 0;
5110       locus = "(anonymous)";
5111     }
5112
5113   constructor_stack = 0;
5114   constructor_range_stack = 0;
5115
5116   missing_braces_mentioned = 0;
5117
5118   spelling_base = 0;
5119   spelling_size = 0;
5120   RESTORE_SPELLING_DEPTH (0);
5121
5122   if (locus)
5123     push_string (locus);
5124 }
5125
5126 void
5127 finish_init ()
5128 {
5129   struct initializer_stack *p = initializer_stack;
5130
5131   /* Output subconstants (string constants, usually)
5132      that were referenced within this initializer and saved up.
5133      Must do this if and only if we called defer_addressed_constants.  */
5134   if (constructor_subconstants_deferred)
5135     output_deferred_addressed_constants ();
5136
5137   /* Free the whole constructor stack of this initializer.  */
5138   while (constructor_stack)
5139     {
5140       struct constructor_stack *q = constructor_stack;
5141       constructor_stack = q->next;
5142       free (q);
5143     }
5144
5145   if (constructor_range_stack)
5146     abort ();
5147
5148   /* Pop back to the data of the outer initializer (if any).  */
5149   constructor_decl = p->decl;
5150   constructor_asmspec = p->asmspec;
5151   require_constant_value = p->require_constant_value;
5152   require_constant_elements = p->require_constant_elements;
5153   constructor_stack = p->constructor_stack;
5154   constructor_range_stack = p->constructor_range_stack;
5155   constructor_elements = p->elements;
5156   spelling = p->spelling;
5157   spelling_base = p->spelling_base;
5158   spelling_size = p->spelling_size;
5159   constructor_subconstants_deferred = p->deferred;
5160   constructor_top_level = p->top_level;
5161   initializer_stack = p->next;
5162   free (p);
5163 }
5164 \f
5165 /* Call here when we see the initializer is surrounded by braces.
5166    This is instead of a call to push_init_level;
5167    it is matched by a call to pop_init_level.
5168
5169    TYPE is the type to initialize, for a constructor expression.
5170    For an initializer for a decl, TYPE is zero.  */
5171
5172 void
5173 really_start_incremental_init (type)
5174      tree type;
5175 {
5176   struct constructor_stack *p
5177     = (struct constructor_stack *) xmalloc (sizeof (struct constructor_stack));
5178
5179   if (type == 0)
5180     type = TREE_TYPE (constructor_decl);
5181
5182   p->type = constructor_type;
5183   p->fields = constructor_fields;
5184   p->index = constructor_index;
5185   p->max_index = constructor_max_index;
5186   p->unfilled_index = constructor_unfilled_index;
5187   p->unfilled_fields = constructor_unfilled_fields;
5188   p->bit_index = constructor_bit_index;
5189   p->elements = constructor_elements;
5190   p->constant = constructor_constant;
5191   p->simple = constructor_simple;
5192   p->erroneous = constructor_erroneous;
5193   p->pending_elts = constructor_pending_elts;
5194   p->depth = constructor_depth;
5195   p->replacement_value = 0;
5196   p->implicit = 0;
5197   p->range_stack = 0;
5198   p->outer = 0;
5199   p->incremental = constructor_incremental;
5200   p->next = 0;
5201   constructor_stack = p;
5202
5203   constructor_constant = 1;
5204   constructor_simple = 1;
5205   constructor_depth = SPELLING_DEPTH ();
5206   constructor_elements = 0;
5207   constructor_pending_elts = 0;
5208   constructor_type = type;
5209   constructor_incremental = 1;
5210   designator_depth = 0;
5211   designator_errorneous = 0;
5212
5213   if (TREE_CODE (constructor_type) == RECORD_TYPE
5214       || TREE_CODE (constructor_type) == UNION_TYPE)
5215     {
5216       constructor_fields = TYPE_FIELDS (constructor_type);
5217       /* Skip any nameless bit fields at the beginning.  */
5218       while (constructor_fields != 0 && DECL_C_BIT_FIELD (constructor_fields)
5219              && DECL_NAME (constructor_fields) == 0)
5220         constructor_fields = TREE_CHAIN (constructor_fields);
5221
5222       constructor_unfilled_fields = constructor_fields;
5223       constructor_bit_index = bitsize_zero_node;
5224     }
5225   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5226     {
5227       if (TYPE_DOMAIN (constructor_type))
5228         {
5229           constructor_max_index
5230             = TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type));
5231
5232           /* Detect non-empty initializations of zero-length arrays.  */
5233           if (constructor_max_index == NULL_TREE)
5234             constructor_max_index = build_int_2 (-1, -1);
5235
5236           constructor_index
5237             = convert (bitsizetype,
5238                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
5239         }
5240       else
5241         constructor_index = bitsize_zero_node;
5242
5243       constructor_unfilled_index = constructor_index;
5244     }
5245   else
5246     {
5247       /* Handle the case of int x = {5}; */
5248       constructor_fields = constructor_type;
5249       constructor_unfilled_fields = constructor_type;
5250     }
5251 }
5252 \f
5253 /* Push down into a subobject, for initialization.
5254    If this is for an explicit set of braces, IMPLICIT is 0.
5255    If it is because the next element belongs at a lower level,
5256    IMPLICIT is 1 (or 2 if the push is because of designator list).  */
5257
5258 void
5259 push_init_level (implicit)
5260      int implicit;
5261 {
5262   struct constructor_stack *p;
5263   tree value = NULL_TREE;
5264
5265   /* If we've exhausted any levels that didn't have braces,
5266      pop them now.  */
5267   while (constructor_stack->implicit)
5268     {
5269       if ((TREE_CODE (constructor_type) == RECORD_TYPE
5270            || TREE_CODE (constructor_type) == UNION_TYPE)
5271           && constructor_fields == 0)
5272         process_init_element (pop_init_level (1));
5273       else if (TREE_CODE (constructor_type) == ARRAY_TYPE
5274                && tree_int_cst_lt (constructor_max_index, constructor_index))
5275         process_init_element (pop_init_level (1));
5276       else
5277         break;
5278     }
5279
5280   /* Unless this is an explicit brace, we need to preserve previous
5281      content if any.  */
5282   if (implicit)
5283     {
5284       if ((TREE_CODE (constructor_type) == RECORD_TYPE
5285            || TREE_CODE (constructor_type) == UNION_TYPE)
5286           && constructor_fields)
5287         value = find_init_member (constructor_fields);
5288       else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5289         value = find_init_member (constructor_index);
5290     }
5291
5292   p = (struct constructor_stack *) xmalloc (sizeof (struct constructor_stack));
5293   p->type = constructor_type;
5294   p->fields = constructor_fields;
5295   p->index = constructor_index;
5296   p->max_index = constructor_max_index;
5297   p->unfilled_index = constructor_unfilled_index;
5298   p->unfilled_fields = constructor_unfilled_fields;
5299   p->bit_index = constructor_bit_index;
5300   p->elements = constructor_elements;
5301   p->constant = constructor_constant;
5302   p->simple = constructor_simple;
5303   p->erroneous = constructor_erroneous;
5304   p->pending_elts = constructor_pending_elts;
5305   p->depth = constructor_depth;
5306   p->replacement_value = 0;
5307   p->implicit = implicit;
5308   p->outer = 0;
5309   p->incremental = constructor_incremental;
5310   p->next = constructor_stack;
5311   p->range_stack = 0;
5312   constructor_stack = p;
5313
5314   constructor_constant = 1;
5315   constructor_simple = 1;
5316   constructor_depth = SPELLING_DEPTH ();
5317   constructor_elements = 0;
5318   constructor_incremental = 1;
5319   constructor_pending_elts = 0;
5320   if (!implicit)
5321     {
5322       p->range_stack = constructor_range_stack;
5323       constructor_range_stack = 0;
5324       designator_depth = 0;
5325       designator_errorneous = 0;
5326     }
5327
5328   /* Don't die if an entire brace-pair level is superfluous
5329      in the containing level.  */
5330   if (constructor_type == 0)
5331     ;
5332   else if (TREE_CODE (constructor_type) == RECORD_TYPE
5333            || TREE_CODE (constructor_type) == UNION_TYPE)
5334     {
5335       /* Don't die if there are extra init elts at the end.  */
5336       if (constructor_fields == 0)
5337         constructor_type = 0;
5338       else
5339         {
5340           constructor_type = TREE_TYPE (constructor_fields);
5341           push_member_name (constructor_fields);
5342           constructor_depth++;
5343         }
5344     }
5345   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5346     {
5347       constructor_type = TREE_TYPE (constructor_type);
5348       push_array_bounds (tree_low_cst (constructor_index, 0));
5349       constructor_depth++;
5350     }
5351
5352   if (constructor_type == 0)
5353     {
5354       error_init ("extra brace group at end of initializer");
5355       constructor_fields = 0;
5356       constructor_unfilled_fields = 0;
5357       return;
5358     }
5359
5360   if (value && TREE_CODE (value) == CONSTRUCTOR)
5361     {
5362       constructor_constant = TREE_CONSTANT (value);
5363       constructor_simple = TREE_STATIC (value);
5364       constructor_elements = TREE_OPERAND (value, 1);
5365       if (constructor_elements
5366           && (TREE_CODE (constructor_type) == RECORD_TYPE
5367               || TREE_CODE (constructor_type) == ARRAY_TYPE))
5368         set_nonincremental_init ();
5369     }
5370
5371   if (implicit == 1 && warn_missing_braces && !missing_braces_mentioned)
5372     {
5373       missing_braces_mentioned = 1;
5374       warning_init ("missing braces around initializer");
5375     }
5376
5377   if (TREE_CODE (constructor_type) == RECORD_TYPE
5378            || TREE_CODE (constructor_type) == UNION_TYPE)
5379     {
5380       constructor_fields = TYPE_FIELDS (constructor_type);
5381       /* Skip any nameless bit fields at the beginning.  */
5382       while (constructor_fields != 0 && DECL_C_BIT_FIELD (constructor_fields)
5383              && DECL_NAME (constructor_fields) == 0)
5384         constructor_fields = TREE_CHAIN (constructor_fields);
5385
5386       constructor_unfilled_fields = constructor_fields;
5387       constructor_bit_index = bitsize_zero_node;
5388     }
5389   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5390     {
5391       if (TYPE_DOMAIN (constructor_type))
5392         {
5393           constructor_max_index
5394             = TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type));
5395           constructor_index
5396             = convert (bitsizetype,
5397                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
5398
5399           /* ??? For GCC 3.1, remove special case initialization of
5400              zero-length array members from pop_init_level and set
5401              constructor_max_index such that we get the normal
5402              "excess elements" warning.  */
5403         }
5404       else
5405         constructor_index = bitsize_zero_node;
5406
5407       constructor_unfilled_index = constructor_index;
5408       if (value && TREE_CODE (value) == STRING_CST)
5409         {
5410           /* We need to split the char/wchar array into individual
5411              characters, so that we don't have to special case it
5412              everywhere.  */
5413           set_nonincremental_init_from_string (value);
5414         }
5415     }
5416   else
5417     {
5418       warning_init ("braces around scalar initializer");
5419       constructor_fields = constructor_type;
5420       constructor_unfilled_fields = constructor_type;
5421     }
5422 }
5423
5424 /* At the end of an implicit or explicit brace level,
5425    finish up that level of constructor.
5426    If we were outputting the elements as they are read, return 0
5427    from inner levels (process_init_element ignores that),
5428    but return error_mark_node from the outermost level
5429    (that's what we want to put in DECL_INITIAL).
5430    Otherwise, return a CONSTRUCTOR expression.  */
5431
5432 tree
5433 pop_init_level (implicit)
5434      int implicit;
5435 {
5436   struct constructor_stack *p;
5437   HOST_WIDE_INT size = 0;
5438   tree constructor = 0;
5439
5440   if (implicit == 0)
5441     {
5442       /* When we come to an explicit close brace,
5443          pop any inner levels that didn't have explicit braces.  */
5444       while (constructor_stack->implicit)
5445         process_init_element (pop_init_level (1));
5446
5447       if (constructor_range_stack)
5448         abort ();
5449     }
5450
5451   p = constructor_stack;
5452
5453   if (constructor_type != 0)
5454     size = int_size_in_bytes (constructor_type);
5455
5456   /* Error for initializing a flexible array member, or a zero-length
5457      array member in an inappropriate context.  */
5458   if (constructor_type && constructor_fields
5459       && TREE_CODE (constructor_type) == ARRAY_TYPE
5460       && TYPE_DOMAIN (constructor_type)
5461       && ! TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type)))
5462     {
5463       /* Silently discard empty initializations.  The parser will
5464          already have pedwarned for empty brackets.  */
5465       if (integer_zerop (constructor_unfilled_index))
5466         constructor_type = NULL_TREE;
5467       else if (! TYPE_SIZE (constructor_type))
5468         {
5469           if (constructor_depth > 2)
5470             error_init ("initialization of flexible array member in a nested context");
5471           else if (pedantic)
5472             pedwarn_init ("initialization of a flexible array member");
5473
5474           /* We have already issued an error message for the existance
5475              of a flexible array member not at the end of the structure.
5476              Discard the initializer so that we do not abort later.  */
5477           if (TREE_CHAIN (constructor_fields) != NULL_TREE)
5478             constructor_type = NULL_TREE;
5479         }
5480       else
5481         {
5482           warning_init ("deprecated initialization of zero-length array");
5483
5484           /* We must be initializing the last member of a top-level struct.  */
5485           if (TREE_CHAIN (constructor_fields) != NULL_TREE)
5486             {
5487               error_init ("initialization of zero-length array before end of structure");
5488               /* Discard the initializer so that we do not abort later.  */
5489               constructor_type = NULL_TREE;
5490             }
5491           else if (constructor_depth > 2)
5492             error_init ("initialization of zero-length array inside a nested context");
5493         }
5494     }
5495
5496   /* Warn when some struct elements are implicitly initialized to zero.  */
5497   if (extra_warnings
5498       && constructor_type
5499       && TREE_CODE (constructor_type) == RECORD_TYPE
5500       && constructor_unfilled_fields)
5501     {
5502         /* Do not warn for flexible array members or zero-length arrays.  */
5503         while (constructor_unfilled_fields
5504                && (! DECL_SIZE (constructor_unfilled_fields)
5505                    || integer_zerop (DECL_SIZE (constructor_unfilled_fields))))
5506           constructor_unfilled_fields = TREE_CHAIN (constructor_unfilled_fields);
5507
5508         if (constructor_unfilled_fields)
5509           {
5510             push_member_name (constructor_unfilled_fields);
5511             warning_init ("missing initializer");
5512             RESTORE_SPELLING_DEPTH (constructor_depth);
5513           }
5514     }
5515
5516   /* Now output all pending elements.  */
5517   constructor_incremental = 1;
5518   output_pending_init_elements (1);
5519
5520   /* Pad out the end of the structure.  */
5521   if (p->replacement_value)
5522     /* If this closes a superfluous brace pair,
5523        just pass out the element between them.  */
5524     constructor = p->replacement_value;
5525   else if (constructor_type == 0)
5526     ;
5527   else if (TREE_CODE (constructor_type) != RECORD_TYPE
5528            && TREE_CODE (constructor_type) != UNION_TYPE
5529            && TREE_CODE (constructor_type) != ARRAY_TYPE)
5530     {
5531       /* A nonincremental scalar initializer--just return
5532          the element, after verifying there is just one.  */
5533       if (constructor_elements == 0)
5534         {
5535           if (!constructor_erroneous)
5536             error_init ("empty scalar initializer");
5537           constructor = error_mark_node;
5538         }
5539       else if (TREE_CHAIN (constructor_elements) != 0)
5540         {
5541           error_init ("extra elements in scalar initializer");
5542           constructor = TREE_VALUE (constructor_elements);
5543         }
5544       else
5545         constructor = TREE_VALUE (constructor_elements);
5546     }
5547   else
5548     {
5549       if (constructor_erroneous)
5550         constructor = error_mark_node;
5551       else
5552         {
5553           constructor = build (CONSTRUCTOR, constructor_type, NULL_TREE,
5554                                nreverse (constructor_elements));
5555           if (constructor_constant)
5556             TREE_CONSTANT (constructor) = 1;
5557           if (constructor_constant && constructor_simple)
5558             TREE_STATIC (constructor) = 1;
5559         }
5560     }
5561
5562   constructor_type = p->type;
5563   constructor_fields = p->fields;
5564   constructor_index = p->index;
5565   constructor_max_index = p->max_index;
5566   constructor_unfilled_index = p->unfilled_index;
5567   constructor_unfilled_fields = p->unfilled_fields;
5568   constructor_bit_index = p->bit_index;
5569   constructor_elements = p->elements;
5570   constructor_constant = p->constant;
5571   constructor_simple = p->simple;
5572   constructor_erroneous = p->erroneous;
5573   constructor_incremental = p->incremental;
5574   constructor_pending_elts = p->pending_elts;
5575   constructor_depth = p->depth;
5576   if (!p->implicit)
5577     constructor_range_stack = p->range_stack;
5578   RESTORE_SPELLING_DEPTH (constructor_depth);
5579
5580   constructor_stack = p->next;
5581   free (p);
5582
5583   if (constructor == 0)
5584     {
5585       if (constructor_stack == 0)
5586         return error_mark_node;
5587       return NULL_TREE;
5588     }
5589   return constructor;
5590 }
5591
5592 /* Common handling for both array range and field name designators.
5593    ARRAY argument is non-zero for array ranges.  Returns zero for success.  */
5594
5595 static int
5596 set_designator (array)
5597      int array;
5598 {
5599   tree subtype;
5600   enum tree_code subcode;
5601
5602   /* Don't die if an entire brace-pair level is superfluous
5603      in the containing level.  */
5604   if (constructor_type == 0)
5605     return 1;
5606
5607   /* If there were errors in this designator list already, bail out silently.  */
5608   if (designator_errorneous)
5609     return 1;
5610
5611   if (!designator_depth)
5612     {
5613       if (constructor_range_stack)
5614         abort ();
5615
5616       /* Designator list starts at the level of closest explicit
5617          braces.  */
5618       while (constructor_stack->implicit)
5619         process_init_element (pop_init_level (1));
5620       return 0;
5621     }
5622
5623   if (constructor_no_implicit)
5624     {
5625       error_init ("initialization designators may not nest");
5626       return 1;
5627     }
5628
5629   if (TREE_CODE (constructor_type) == RECORD_TYPE
5630       || TREE_CODE (constructor_type) == UNION_TYPE)
5631     {
5632       subtype = TREE_TYPE (constructor_fields);
5633       if (subtype != error_mark_node)
5634         subtype = TYPE_MAIN_VARIANT (subtype);
5635     }
5636   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5637     {
5638       subtype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
5639     }
5640   else
5641     abort ();
5642
5643   subcode = TREE_CODE (subtype);
5644   if (array && subcode != ARRAY_TYPE)
5645     {
5646       error_init ("array index in non-array initializer");
5647       return 1;
5648     }
5649   else if (!array && subcode != RECORD_TYPE && subcode != UNION_TYPE)
5650     {
5651       error_init ("field name not in record or union initializer");
5652       return 1;
5653     }
5654
5655   push_init_level (2);
5656   return 0;
5657 }
5658
5659 /* If there are range designators in designator list, push a new designator
5660    to constructor_range_stack.  RANGE_END is end of such stack range or
5661    NULL_TREE if there is no range designator at this level.  */
5662
5663 static void
5664 push_range_stack (range_end)
5665      tree range_end;
5666 {
5667   struct constructor_range_stack *p;
5668
5669   p = (struct constructor_range_stack *)
5670       ggc_alloc (sizeof (struct constructor_range_stack));
5671   p->prev = constructor_range_stack;
5672   p->next = 0;
5673   p->fields = constructor_fields;
5674   p->range_start = constructor_index;
5675   p->index = constructor_index;
5676   p->stack = constructor_stack;
5677   p->range_end = range_end;
5678   if (constructor_range_stack)
5679     constructor_range_stack->next = p;
5680   constructor_range_stack = p;
5681 }
5682
5683 /* Within an array initializer, specify the next index to be initialized.
5684    FIRST is that index.  If LAST is nonzero, then initialize a range
5685    of indices, running from FIRST through LAST.  */
5686
5687 void
5688 set_init_index (first, last)
5689      tree first, last;
5690 {
5691   if (set_designator (1))
5692     return;
5693
5694   designator_errorneous = 1;
5695
5696   while ((TREE_CODE (first) == NOP_EXPR
5697           || TREE_CODE (first) == CONVERT_EXPR
5698           || TREE_CODE (first) == NON_LVALUE_EXPR)
5699          && (TYPE_MODE (TREE_TYPE (first))
5700              == TYPE_MODE (TREE_TYPE (TREE_OPERAND (first, 0)))))
5701     first = TREE_OPERAND (first, 0);
5702
5703   if (last)
5704     while ((TREE_CODE (last) == NOP_EXPR
5705             || TREE_CODE (last) == CONVERT_EXPR
5706             || TREE_CODE (last) == NON_LVALUE_EXPR)
5707            && (TYPE_MODE (TREE_TYPE (last))
5708                == TYPE_MODE (TREE_TYPE (TREE_OPERAND (last, 0)))))
5709       last = TREE_OPERAND (last, 0);
5710
5711   if (TREE_CODE (first) != INTEGER_CST)
5712     error_init ("nonconstant array index in initializer");
5713   else if (last != 0 && TREE_CODE (last) != INTEGER_CST)
5714     error_init ("nonconstant array index in initializer");
5715   else if (TREE_CODE (constructor_type) != ARRAY_TYPE)
5716     error_init ("array index in non-array initializer");
5717   else if (constructor_max_index
5718            && tree_int_cst_lt (constructor_max_index, first))
5719     error_init ("array index in initializer exceeds array bounds");
5720   else
5721     {
5722       constructor_index = convert (bitsizetype, first);
5723
5724       if (last)
5725         {
5726           if (tree_int_cst_equal (first, last))
5727             last = 0;
5728           else if (tree_int_cst_lt (last, first))
5729             {
5730               error_init ("empty index range in initializer");
5731               last = 0;
5732             }
5733           else
5734             {
5735               last = convert (bitsizetype, last);
5736               if (constructor_max_index != 0
5737                   && tree_int_cst_lt (constructor_max_index, last))
5738                 {
5739                   error_init ("array index range in initializer exceeds array bounds");
5740                   last = 0;
5741                 }
5742             }
5743         }
5744
5745       designator_depth++;
5746       designator_errorneous = 0;
5747       if (constructor_range_stack || last)
5748         push_range_stack (last);
5749     }
5750 }
5751
5752 /* Within a struct initializer, specify the next field to be initialized.  */
5753
5754 void
5755 set_init_label (fieldname)
5756      tree fieldname;
5757 {
5758   tree tail;
5759
5760   if (set_designator (0))
5761     return;
5762
5763   designator_errorneous = 1;
5764
5765   if (TREE_CODE (constructor_type) != RECORD_TYPE
5766       && TREE_CODE (constructor_type) != UNION_TYPE)
5767     {
5768       error_init ("field name not in record or union initializer");
5769       return;
5770     }
5771
5772   for (tail = TYPE_FIELDS (constructor_type); tail;
5773        tail = TREE_CHAIN (tail))
5774     {
5775       if (DECL_NAME (tail) == fieldname)
5776         break;
5777     }
5778
5779   if (tail == 0)
5780     error ("unknown field `%s' specified in initializer",
5781            IDENTIFIER_POINTER (fieldname));
5782   else
5783     {
5784       constructor_fields = tail;
5785       designator_depth++;
5786       designator_errorneous = 0;
5787       if (constructor_range_stack)
5788         push_range_stack (NULL_TREE);
5789     }
5790 }
5791 \f
5792 /* Add a new initializer to the tree of pending initializers.  PURPOSE
5793    indentifies the initializer, either array index or field in a structure.
5794    VALUE is the value of that index or field.  */
5795
5796 static void
5797 add_pending_init (purpose, value)
5798      tree purpose, value;
5799 {
5800   struct init_node *p, **q, *r;
5801
5802   q = &constructor_pending_elts;
5803   p = 0;
5804
5805   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5806     {
5807       while (*q != 0)
5808         {
5809           p = *q;
5810           if (tree_int_cst_lt (purpose, p->purpose))
5811             q = &p->left;
5812           else if (tree_int_cst_lt (p->purpose, purpose))
5813             q = &p->right;
5814           else
5815             {
5816               if (TREE_SIDE_EFFECTS (p->value))
5817                 warning_init ("initialized field with side-effects overwritten");
5818               p->value = value;
5819               return;
5820             }
5821         }
5822     }
5823   else
5824     {
5825       tree bitpos;
5826
5827       bitpos = bit_position (purpose);
5828       while (*q != NULL)
5829         {
5830           p = *q;
5831           if (tree_int_cst_lt (bitpos, bit_position (p->purpose)))
5832             q = &p->left;
5833           else if (p->purpose != purpose)
5834             q = &p->right;
5835           else
5836             {
5837               if (TREE_SIDE_EFFECTS (p->value))
5838                 warning_init ("initialized field with side-effects overwritten");
5839               p->value = value;
5840               return;
5841             }
5842         }
5843     }
5844
5845   r = (struct init_node *) ggc_alloc (sizeof (struct init_node));
5846   r->purpose = purpose;
5847   r->value = value;
5848
5849   *q = r;
5850   r->parent = p;
5851   r->left = 0;
5852   r->right = 0;
5853   r->balance = 0;
5854
5855   while (p)
5856     {
5857       struct init_node *s;
5858
5859       if (r == p->left)
5860         {
5861           if (p->balance == 0)
5862             p->balance = -1;
5863           else if (p->balance < 0)
5864             {
5865               if (r->balance < 0)
5866                 {
5867                   /* L rotation. */
5868                   p->left = r->right;
5869                   if (p->left)
5870                     p->left->parent = p;
5871                   r->right = p;
5872
5873                   p->balance = 0;
5874                   r->balance = 0;
5875
5876                   s = p->parent;
5877                   p->parent = r;
5878                   r->parent = s;
5879                   if (s)
5880                     {
5881                       if (s->left == p)
5882                         s->left = r;
5883                       else
5884                         s->right = r;
5885                     }
5886                   else
5887                     constructor_pending_elts = r;
5888                 }
5889               else
5890                 {
5891                   /* LR rotation. */
5892                   struct init_node *t = r->right;
5893
5894                   r->right = t->left;
5895                   if (r->right)
5896                     r->right->parent = r;
5897                   t->left = r;
5898
5899                   p->left = t->right;
5900                   if (p->left)
5901                     p->left->parent = p;
5902                   t->right = p;
5903
5904                   p->balance = t->balance < 0;
5905                   r->balance = -(t->balance > 0);
5906                   t->balance = 0;
5907
5908                   s = p->parent;
5909                   p->parent = t;
5910                   r->parent = t;
5911                   t->parent = s;
5912                   if (s)
5913                     {
5914                       if (s->left == p)
5915                         s->left = t;
5916                       else
5917                         s->right = t;
5918                     }
5919                   else
5920                     constructor_pending_elts = t;
5921                 }
5922               break;
5923             }
5924           else
5925             {
5926               /* p->balance == +1; growth of left side balances the node.  */
5927               p->balance = 0;
5928               break;
5929             }
5930         }
5931       else /* r == p->right */
5932         {
5933           if (p->balance == 0)
5934             /* Growth propagation from right side.  */
5935             p->balance++;
5936           else if (p->balance > 0)
5937             {
5938               if (r->balance > 0)
5939                 {
5940                   /* R rotation. */
5941                   p->right = r->left;
5942                   if (p->right)
5943                     p->right->parent = p;
5944                   r->left = p;
5945
5946                   p->balance = 0;
5947                   r->balance = 0;
5948
5949                   s = p->parent;
5950                   p->parent = r;
5951                   r->parent = s;
5952                   if (s)
5953                     {
5954                       if (s->left == p)
5955                         s->left = r;
5956                       else
5957                         s->right = r;
5958                     }
5959                   else
5960                     constructor_pending_elts = r;
5961                 }
5962               else /* r->balance == -1 */
5963                 {
5964                   /* RL rotation */
5965                   struct init_node *t = r->left;
5966
5967                   r->left = t->right;
5968                   if (r->left)
5969                     r->left->parent = r;
5970                   t->right = r;
5971
5972                   p->right = t->left;
5973                   if (p->right)
5974                     p->right->parent = p;
5975                   t->left = p;
5976
5977                   r->balance = (t->balance < 0);
5978                   p->balance = -(t->balance > 0);
5979                   t->balance = 0;
5980
5981                   s = p->parent;
5982                   p->parent = t;
5983                   r->parent = t;
5984                   t->parent = s;
5985                   if (s)
5986                     {
5987                       if (s->left == p)
5988                         s->left = t;
5989                       else
5990                         s->right = t;
5991                     }
5992                   else
5993                     constructor_pending_elts = t;
5994                 }
5995               break;
5996             }
5997           else
5998             {
5999               /* p->balance == -1; growth of right side balances the node. */
6000               p->balance = 0;
6001               break;
6002             }
6003         }
6004
6005       r = p;
6006       p = p->parent;
6007     }
6008 }
6009
6010 /* Build AVL tree from a sorted chain.  */
6011
6012 static void
6013 set_nonincremental_init ()
6014 {
6015   tree chain;
6016
6017   if (TREE_CODE (constructor_type) != RECORD_TYPE
6018       && TREE_CODE (constructor_type) != ARRAY_TYPE)
6019     return;
6020
6021   for (chain = constructor_elements; chain; chain = TREE_CHAIN (chain))
6022     add_pending_init (TREE_PURPOSE (chain), TREE_VALUE (chain));
6023   constructor_elements = 0;
6024   if (TREE_CODE (constructor_type) == RECORD_TYPE)
6025     {
6026       constructor_unfilled_fields = TYPE_FIELDS (constructor_type);
6027       /* Skip any nameless bit fields at the beginning.  */
6028       while (constructor_unfilled_fields != 0
6029              && DECL_C_BIT_FIELD (constructor_unfilled_fields)
6030              && DECL_NAME (constructor_unfilled_fields) == 0)
6031         constructor_unfilled_fields = TREE_CHAIN (constructor_unfilled_fields);
6032
6033     }
6034   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6035     {
6036       if (TYPE_DOMAIN (constructor_type))
6037         constructor_unfilled_index
6038             = convert (bitsizetype,
6039                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
6040       else
6041         constructor_unfilled_index = bitsize_zero_node;
6042     }
6043   constructor_incremental = 0;
6044 }
6045
6046 /* Build AVL tree from a string constant.  */
6047
6048 static void
6049 set_nonincremental_init_from_string (str)
6050      tree str;
6051 {
6052   tree value, purpose, type;
6053   HOST_WIDE_INT val[2];
6054   const char *p, *end;
6055   int byte, wchar_bytes, charwidth, bitpos;
6056
6057   if (TREE_CODE (constructor_type) != ARRAY_TYPE)
6058     abort ();
6059
6060   if (TYPE_PRECISION (TREE_TYPE (TREE_TYPE (str)))
6061       == TYPE_PRECISION (char_type_node))
6062     wchar_bytes = 1;
6063   else if (TYPE_PRECISION (TREE_TYPE (TREE_TYPE (str)))
6064            == TYPE_PRECISION (wchar_type_node))
6065     wchar_bytes = TYPE_PRECISION (wchar_type_node) / BITS_PER_UNIT;
6066   else
6067     abort ();
6068
6069   charwidth = TYPE_PRECISION (char_type_node);
6070   type = TREE_TYPE (constructor_type);
6071   p = TREE_STRING_POINTER (str);
6072   end = p + TREE_STRING_LENGTH (str);
6073
6074   for (purpose = bitsize_zero_node;
6075        p < end && !tree_int_cst_lt (constructor_max_index, purpose);
6076        purpose = size_binop (PLUS_EXPR, purpose, bitsize_one_node))
6077     {
6078       if (wchar_bytes == 1)
6079         {
6080           val[1] = (unsigned char) *p++;
6081           val[0] = 0;
6082         }
6083       else
6084         {
6085           val[0] = 0;
6086           val[1] = 0;
6087           for (byte = 0; byte < wchar_bytes; byte++)
6088             {
6089               if (BYTES_BIG_ENDIAN)
6090                 bitpos = (wchar_bytes - byte - 1) * charwidth;
6091               else
6092                 bitpos = byte * charwidth;
6093               val[bitpos < HOST_BITS_PER_WIDE_INT]
6094                 |= ((unsigned HOST_WIDE_INT) ((unsigned char) *p++))
6095                    << (bitpos % HOST_BITS_PER_WIDE_INT);
6096             }
6097         }
6098
6099       if (!TREE_UNSIGNED (type))
6100         {
6101           bitpos = ((wchar_bytes - 1) * charwidth) + HOST_BITS_PER_CHAR;
6102           if (bitpos < HOST_BITS_PER_WIDE_INT)
6103             {
6104               if (val[1] & (((HOST_WIDE_INT) 1) << (bitpos - 1)))
6105                 {
6106                   val[1] |= ((HOST_WIDE_INT) -1) << bitpos;
6107                   val[0] = -1;
6108                 }
6109             }
6110           else if (bitpos == HOST_BITS_PER_WIDE_INT)
6111             {
6112               if (val[1] < 0)
6113                 val[0] = -1;
6114             }
6115           else if (val[0] & (((HOST_WIDE_INT) 1)
6116                              << (bitpos - 1 - HOST_BITS_PER_WIDE_INT)))
6117             val[0] |= ((HOST_WIDE_INT) -1)
6118                       << (bitpos - HOST_BITS_PER_WIDE_INT);
6119         }
6120
6121       value = build_int_2 (val[1], val[0]);
6122       TREE_TYPE (value) = type;
6123       add_pending_init (purpose, value);
6124     }
6125
6126   constructor_incremental = 0;
6127 }
6128
6129 /* Return value of FIELD in pending initializer or zero if the field was
6130    not initialized yet.  */
6131
6132 static tree
6133 find_init_member (field)
6134      tree field;
6135 {
6136   struct init_node *p;
6137
6138   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6139     {
6140       if (constructor_incremental
6141           && tree_int_cst_lt (field, constructor_unfilled_index))
6142         set_nonincremental_init ();
6143
6144       p = constructor_pending_elts;
6145       while (p)
6146         {
6147           if (tree_int_cst_lt (field, p->purpose))
6148             p = p->left;
6149           else if (tree_int_cst_lt (p->purpose, field))
6150             p = p->right;
6151           else
6152             return p->value;
6153         }
6154     }
6155   else if (TREE_CODE (constructor_type) == RECORD_TYPE)
6156     {
6157       tree bitpos = bit_position (field);
6158
6159       if (constructor_incremental
6160           && (!constructor_unfilled_fields
6161               || tree_int_cst_lt (bitpos,
6162                                   bit_position (constructor_unfilled_fields))))
6163         set_nonincremental_init ();
6164
6165       p = constructor_pending_elts;
6166       while (p)
6167         {
6168           if (field == p->purpose)
6169             return p->value;
6170           else if (tree_int_cst_lt (bitpos, bit_position (p->purpose)))
6171             p = p->left;
6172           else
6173             p = p->right;
6174         }
6175     }
6176   else if (TREE_CODE (constructor_type) == UNION_TYPE)
6177     {
6178       if (constructor_elements
6179           && TREE_PURPOSE (constructor_elements) == field)
6180         return TREE_VALUE (constructor_elements);
6181     }
6182   return 0;
6183 }
6184
6185 /* "Output" the next constructor element.
6186    At top level, really output it to assembler code now.
6187    Otherwise, collect it in a list from which we will make a CONSTRUCTOR.
6188    TYPE is the data type that the containing data type wants here.
6189    FIELD is the field (a FIELD_DECL) or the index that this element fills.
6190
6191    PENDING if non-nil means output pending elements that belong
6192    right after this element.  (PENDING is normally 1;
6193    it is 0 while outputting pending elements, to avoid recursion.)  */
6194
6195 static void
6196 output_init_element (value, type, field, pending)
6197      tree value, type, field;
6198      int pending;
6199 {
6200   if (TREE_CODE (TREE_TYPE (value)) == FUNCTION_TYPE
6201       || (TREE_CODE (TREE_TYPE (value)) == ARRAY_TYPE
6202           && !(TREE_CODE (value) == STRING_CST
6203                && TREE_CODE (type) == ARRAY_TYPE
6204                && TREE_CODE (TREE_TYPE (type)) == INTEGER_TYPE)
6205           && !comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (value)),
6206                          TYPE_MAIN_VARIANT (type))))
6207     value = default_conversion (value);
6208
6209   if (value == error_mark_node)
6210     constructor_erroneous = 1;
6211   else if (!TREE_CONSTANT (value))
6212     constructor_constant = 0;
6213   else if (initializer_constant_valid_p (value, TREE_TYPE (value)) == 0
6214            || ((TREE_CODE (constructor_type) == RECORD_TYPE
6215                 || TREE_CODE (constructor_type) == UNION_TYPE)
6216                && DECL_C_BIT_FIELD (field)
6217                && TREE_CODE (value) != INTEGER_CST))
6218     constructor_simple = 0;
6219
6220   if (require_constant_value && ! TREE_CONSTANT (value))
6221     {
6222       error_init ("initializer element is not constant");
6223       value = error_mark_node;
6224     }
6225   else if (require_constant_elements
6226            && initializer_constant_valid_p (value, TREE_TYPE (value)) == 0)
6227     pedwarn ("initializer element is not computable at load time");
6228
6229   /* If this field is empty (and not at the end of structure),
6230      don't do anything other than checking the initializer.  */
6231   if (field
6232       && (TREE_TYPE (field) == error_mark_node
6233           || (COMPLETE_TYPE_P (TREE_TYPE (field))
6234               && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))
6235               && (TREE_CODE (constructor_type) == ARRAY_TYPE
6236                   || TREE_CHAIN (field)))))
6237     return;
6238
6239   if (value == error_mark_node)
6240     {
6241       constructor_erroneous = 1;
6242       return;
6243     }
6244
6245   /* If this element doesn't come next in sequence,
6246      put it on constructor_pending_elts.  */
6247   if (TREE_CODE (constructor_type) == ARRAY_TYPE
6248       && (!constructor_incremental
6249           || !tree_int_cst_equal (field, constructor_unfilled_index)))
6250     {
6251       if (constructor_incremental
6252           && tree_int_cst_lt (field, constructor_unfilled_index))
6253         set_nonincremental_init ();
6254
6255       add_pending_init (field,
6256                         digest_init (type, value, require_constant_value,
6257                                      require_constant_elements));
6258       return;
6259     }
6260   else if (TREE_CODE (constructor_type) == RECORD_TYPE
6261            && (!constructor_incremental
6262                || field != constructor_unfilled_fields))
6263     {
6264       /* We do this for records but not for unions.  In a union,
6265          no matter which field is specified, it can be initialized
6266          right away since it starts at the beginning of the union.  */
6267       if (constructor_incremental)
6268         {
6269           if (!constructor_unfilled_fields)
6270             set_nonincremental_init ();
6271           else
6272             {
6273               tree bitpos, unfillpos;
6274
6275               bitpos = bit_position (field);
6276               unfillpos = bit_position (constructor_unfilled_fields);
6277
6278               if (tree_int_cst_lt (bitpos, unfillpos))
6279                 set_nonincremental_init ();
6280             }
6281         }
6282
6283       add_pending_init (field,
6284                         digest_init (type, value, require_constant_value,
6285                                      require_constant_elements));
6286       return;
6287     }
6288   else if (TREE_CODE (constructor_type) == UNION_TYPE
6289            && constructor_elements)
6290     {
6291       if (TREE_SIDE_EFFECTS (TREE_VALUE (constructor_elements)))
6292         warning_init ("initialized field with side-effects overwritten");
6293
6294       /* We can have just one union field set.  */
6295       constructor_elements = 0;
6296     }
6297
6298   /* Otherwise, output this element either to
6299      constructor_elements or to the assembler file.  */
6300
6301   if (field && TREE_CODE (field) == INTEGER_CST)
6302     field = copy_node (field);
6303   constructor_elements
6304     = tree_cons (field, digest_init (type, value,
6305                                      require_constant_value,
6306                                      require_constant_elements),
6307                  constructor_elements);
6308
6309   /* Advance the variable that indicates sequential elements output.  */
6310   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6311     constructor_unfilled_index
6312       = size_binop (PLUS_EXPR, constructor_unfilled_index,
6313                     bitsize_one_node);
6314   else if (TREE_CODE (constructor_type) == RECORD_TYPE)
6315     {
6316       constructor_unfilled_fields
6317         = TREE_CHAIN (constructor_unfilled_fields);
6318
6319       /* Skip any nameless bit fields.  */
6320       while (constructor_unfilled_fields != 0
6321              && DECL_C_BIT_FIELD (constructor_unfilled_fields)
6322              && DECL_NAME (constructor_unfilled_fields) == 0)
6323         constructor_unfilled_fields =
6324           TREE_CHAIN (constructor_unfilled_fields);
6325     }
6326   else if (TREE_CODE (constructor_type) == UNION_TYPE)
6327     constructor_unfilled_fields = 0;
6328
6329   /* Now output any pending elements which have become next.  */
6330   if (pending)
6331     output_pending_init_elements (0);
6332 }
6333
6334 /* Output any pending elements which have become next.
6335    As we output elements, constructor_unfilled_{fields,index}
6336    advances, which may cause other elements to become next;
6337    if so, they too are output.
6338
6339    If ALL is 0, we return when there are
6340    no more pending elements to output now.
6341
6342    If ALL is 1, we output space as necessary so that
6343    we can output all the pending elements.  */
6344
6345 static void
6346 output_pending_init_elements (all)
6347      int all;
6348 {
6349   struct init_node *elt = constructor_pending_elts;
6350   tree next;
6351
6352  retry:
6353
6354   /* Look thru the whole pending tree.
6355      If we find an element that should be output now,
6356      output it.  Otherwise, set NEXT to the element
6357      that comes first among those still pending.  */
6358
6359   next = 0;
6360   while (elt)
6361     {
6362       if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6363         {
6364           if (tree_int_cst_equal (elt->purpose,
6365                                   constructor_unfilled_index))
6366             output_init_element (elt->value,
6367                                  TREE_TYPE (constructor_type),
6368                                  constructor_unfilled_index, 0);
6369           else if (tree_int_cst_lt (constructor_unfilled_index,
6370                                     elt->purpose))
6371             {
6372               /* Advance to the next smaller node.  */
6373               if (elt->left)
6374                 elt = elt->left;
6375               else
6376                 {
6377                   /* We have reached the smallest node bigger than the
6378                      current unfilled index.  Fill the space first.  */
6379                   next = elt->purpose;
6380                   break;
6381                 }
6382             }
6383           else
6384             {
6385               /* Advance to the next bigger node.  */
6386               if (elt->right)
6387                 elt = elt->right;
6388               else
6389                 {
6390                   /* We have reached the biggest node in a subtree.  Find
6391                      the parent of it, which is the next bigger node.  */
6392                   while (elt->parent && elt->parent->right == elt)
6393                     elt = elt->parent;
6394                   elt = elt->parent;
6395                   if (elt && tree_int_cst_lt (constructor_unfilled_index,
6396                                               elt->purpose))
6397                     {
6398                       next = elt->purpose;
6399                       break;
6400                     }
6401                 }
6402             }
6403         }
6404       else if (TREE_CODE (constructor_type) == RECORD_TYPE
6405                || TREE_CODE (constructor_type) == UNION_TYPE)
6406         {
6407           tree ctor_unfilled_bitpos, elt_bitpos;
6408
6409           /* If the current record is complete we are done.  */
6410           if (constructor_unfilled_fields == 0)
6411             break;
6412
6413           ctor_unfilled_bitpos = bit_position (constructor_unfilled_fields);
6414           elt_bitpos = bit_position (elt->purpose);
6415           /* We can't compare fields here because there might be empty
6416              fields in between.  */
6417           if (tree_int_cst_equal (elt_bitpos, ctor_unfilled_bitpos))
6418             {
6419               constructor_unfilled_fields = elt->purpose;
6420               output_init_element (elt->value, TREE_TYPE (elt->purpose),
6421                                    elt->purpose, 0);
6422             }
6423           else if (tree_int_cst_lt (ctor_unfilled_bitpos, elt_bitpos))
6424             {
6425               /* Advance to the next smaller node.  */
6426               if (elt->left)
6427                 elt = elt->left;
6428               else
6429                 {
6430                   /* We have reached the smallest node bigger than the
6431                      current unfilled field.  Fill the space first.  */
6432                   next = elt->purpose;
6433                   break;
6434                 }
6435             }
6436           else
6437             {
6438               /* Advance to the next bigger node.  */
6439               if (elt->right)
6440                 elt = elt->right;
6441               else
6442                 {
6443                   /* We have reached the biggest node in a subtree.  Find
6444                      the parent of it, which is the next bigger node.  */
6445                   while (elt->parent && elt->parent->right == elt)
6446                     elt = elt->parent;
6447                   elt = elt->parent;
6448                   if (elt
6449                       && (tree_int_cst_lt (ctor_unfilled_bitpos,
6450                                            bit_position (elt->purpose))))
6451                     {
6452                       next = elt->purpose;
6453                       break;
6454                     }
6455                 }
6456             }
6457         }
6458     }
6459
6460   /* Ordinarily return, but not if we want to output all
6461      and there are elements left.  */
6462   if (! (all && next != 0))
6463     return;
6464
6465   /* If it's not incremental, just skip over the gap, so that after
6466      jumping to retry we will output the next successive element.  */
6467   if (TREE_CODE (constructor_type) == RECORD_TYPE
6468       || TREE_CODE (constructor_type) == UNION_TYPE)
6469     constructor_unfilled_fields = next;
6470   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6471     constructor_unfilled_index = next;
6472
6473   /* ELT now points to the node in the pending tree with the next
6474      initializer to output.  */
6475   goto retry;
6476 }
6477 \f
6478 /* Add one non-braced element to the current constructor level.
6479    This adjusts the current position within the constructor's type.
6480    This may also start or terminate implicit levels
6481    to handle a partly-braced initializer.
6482
6483    Once this has found the correct level for the new element,
6484    it calls output_init_element.  */
6485
6486 void
6487 process_init_element (value)
6488      tree value;
6489 {
6490   tree orig_value = value;
6491   int string_flag = value != 0 && TREE_CODE (value) == STRING_CST;
6492
6493   designator_depth = 0;
6494   designator_errorneous = 0;
6495
6496   /* Handle superfluous braces around string cst as in
6497      char x[] = {"foo"}; */
6498   if (string_flag
6499       && constructor_type
6500       && TREE_CODE (constructor_type) == ARRAY_TYPE
6501       && TREE_CODE (TREE_TYPE (constructor_type)) == INTEGER_TYPE
6502       && integer_zerop (constructor_unfilled_index))
6503     {
6504       if (constructor_stack->replacement_value)
6505         error_init ("excess elements in char array initializer");
6506       constructor_stack->replacement_value = value;
6507       return;
6508     }
6509
6510   if (constructor_stack->replacement_value != 0)
6511     {
6512       error_init ("excess elements in struct initializer");
6513       return;
6514     }
6515
6516   /* Ignore elements of a brace group if it is entirely superfluous
6517      and has already been diagnosed.  */
6518   if (constructor_type == 0)
6519     return;
6520
6521   /* If we've exhausted any levels that didn't have braces,
6522      pop them now.  */
6523   while (constructor_stack->implicit)
6524     {
6525       if ((TREE_CODE (constructor_type) == RECORD_TYPE
6526            || TREE_CODE (constructor_type) == UNION_TYPE)
6527           && constructor_fields == 0)
6528         process_init_element (pop_init_level (1));
6529       else if (TREE_CODE (constructor_type) == ARRAY_TYPE
6530                && (constructor_max_index == 0
6531                    || tree_int_cst_lt (constructor_max_index,
6532                                        constructor_index)))
6533         process_init_element (pop_init_level (1));
6534       else
6535         break;
6536     }
6537
6538   /* In the case of [LO ... HI] = VALUE, only evaluate VALUE once.  */
6539   if (constructor_range_stack)
6540     value = save_expr (value);
6541
6542   while (1)
6543     {
6544       if (TREE_CODE (constructor_type) == RECORD_TYPE)
6545         {
6546           tree fieldtype;
6547           enum tree_code fieldcode;
6548
6549           if (constructor_fields == 0)
6550             {
6551               pedwarn_init ("excess elements in struct initializer");
6552               break;
6553             }
6554
6555           fieldtype = TREE_TYPE (constructor_fields);
6556           if (fieldtype != error_mark_node)
6557             fieldtype = TYPE_MAIN_VARIANT (fieldtype);
6558           fieldcode = TREE_CODE (fieldtype);
6559
6560           /* Accept a string constant to initialize a subarray.  */
6561           if (value != 0
6562               && fieldcode == ARRAY_TYPE
6563               && TREE_CODE (TREE_TYPE (fieldtype)) == INTEGER_TYPE
6564               && string_flag)
6565             value = orig_value;
6566           /* Otherwise, if we have come to a subaggregate,
6567              and we don't have an element of its type, push into it.  */
6568           else if (value != 0 && !constructor_no_implicit
6569                    && value != error_mark_node
6570                    && TYPE_MAIN_VARIANT (TREE_TYPE (value)) != fieldtype
6571                    && (fieldcode == RECORD_TYPE || fieldcode == ARRAY_TYPE
6572                        || fieldcode == UNION_TYPE))
6573             {
6574               push_init_level (1);
6575               continue;
6576             }
6577
6578           if (value)
6579             {
6580               push_member_name (constructor_fields);
6581               output_init_element (value, fieldtype, constructor_fields, 1);
6582               RESTORE_SPELLING_DEPTH (constructor_depth);
6583             }
6584           else
6585             /* Do the bookkeeping for an element that was
6586                directly output as a constructor.  */
6587             {
6588               /* For a record, keep track of end position of last field.  */
6589               if (DECL_SIZE (constructor_fields))
6590                 constructor_bit_index
6591                   = size_binop (PLUS_EXPR,
6592                                 bit_position (constructor_fields),
6593                                 DECL_SIZE (constructor_fields));
6594
6595               constructor_unfilled_fields = TREE_CHAIN (constructor_fields);
6596               /* Skip any nameless bit fields.  */
6597               while (constructor_unfilled_fields != 0
6598                      && DECL_C_BIT_FIELD (constructor_unfilled_fields)
6599                      && DECL_NAME (constructor_unfilled_fields) == 0)
6600                 constructor_unfilled_fields =
6601                   TREE_CHAIN (constructor_unfilled_fields);
6602             }
6603
6604           constructor_fields = TREE_CHAIN (constructor_fields);
6605           /* Skip any nameless bit fields at the beginning.  */
6606           while (constructor_fields != 0
6607                  && DECL_C_BIT_FIELD (constructor_fields)
6608                  && DECL_NAME (constructor_fields) == 0)
6609             constructor_fields = TREE_CHAIN (constructor_fields);
6610         }
6611       else if (TREE_CODE (constructor_type) == UNION_TYPE)
6612         {
6613           tree fieldtype;
6614           enum tree_code fieldcode;
6615
6616           if (constructor_fields == 0)
6617             {
6618               pedwarn_init ("excess elements in union initializer");
6619               break;
6620             }
6621
6622           fieldtype = TREE_TYPE (constructor_fields);
6623           if (fieldtype != error_mark_node)
6624             fieldtype = TYPE_MAIN_VARIANT (fieldtype);
6625           fieldcode = TREE_CODE (fieldtype);
6626
6627           /* Warn that traditional C rejects initialization of unions.
6628              We skip the warning if the value is zero.  This is done
6629              under the assumption that the zero initializer in user
6630              code appears conditioned on e.g. __STDC__ to avoid
6631              "missing initializer" warnings and relies on default
6632              initialization to zero in the traditional C case.  */
6633           if (warn_traditional && !in_system_header
6634               && !(value && (integer_zerop (value) || real_zerop (value))))
6635             warning ("traditional C rejects initialization of unions");
6636
6637           /* Accept a string constant to initialize a subarray.  */
6638           if (value != 0
6639               && fieldcode == ARRAY_TYPE
6640               && TREE_CODE (TREE_TYPE (fieldtype)) == INTEGER_TYPE
6641               && string_flag)
6642             value = orig_value;
6643           /* Otherwise, if we have come to a subaggregate,
6644              and we don't have an element of its type, push into it.  */
6645           else if (value != 0 && !constructor_no_implicit
6646                    && value != error_mark_node
6647                    && TYPE_MAIN_VARIANT (TREE_TYPE (value)) != fieldtype
6648                    && (fieldcode == RECORD_TYPE || fieldcode == ARRAY_TYPE
6649                        || fieldcode == UNION_TYPE))
6650             {
6651               push_init_level (1);
6652               continue;
6653             }
6654
6655           if (value)
6656             {
6657               push_member_name (constructor_fields);
6658               output_init_element (value, fieldtype, constructor_fields, 1);
6659               RESTORE_SPELLING_DEPTH (constructor_depth);
6660             }
6661           else
6662             /* Do the bookkeeping for an element that was
6663                directly output as a constructor.  */
6664             {
6665               constructor_bit_index = DECL_SIZE (constructor_fields);
6666               constructor_unfilled_fields = TREE_CHAIN (constructor_fields);
6667             }
6668
6669           constructor_fields = 0;
6670         }
6671       else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6672         {
6673           tree elttype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
6674           enum tree_code eltcode = TREE_CODE (elttype);
6675
6676           /* Accept a string constant to initialize a subarray.  */
6677           if (value != 0
6678               && eltcode == ARRAY_TYPE
6679               && TREE_CODE (TREE_TYPE (elttype)) == INTEGER_TYPE
6680               && string_flag)
6681             value = orig_value;
6682           /* Otherwise, if we have come to a subaggregate,
6683              and we don't have an element of its type, push into it.  */
6684           else if (value != 0 && !constructor_no_implicit
6685                    && value != error_mark_node
6686                    && TYPE_MAIN_VARIANT (TREE_TYPE (value)) != elttype
6687                    && (eltcode == RECORD_TYPE || eltcode == ARRAY_TYPE
6688                        || eltcode == UNION_TYPE))
6689             {
6690               push_init_level (1);
6691               continue;
6692             }
6693
6694           if (constructor_max_index != 0
6695               && (tree_int_cst_lt (constructor_max_index, constructor_index)
6696                   || integer_all_onesp (constructor_max_index)))
6697             {
6698               pedwarn_init ("excess elements in array initializer");
6699               break;
6700             }
6701
6702           /* Now output the actual element.  */
6703           if (value)
6704             {
6705               push_array_bounds (tree_low_cst (constructor_index, 0));
6706               output_init_element (value, elttype, constructor_index, 1);
6707               RESTORE_SPELLING_DEPTH (constructor_depth);
6708             }
6709
6710           constructor_index
6711             = size_binop (PLUS_EXPR, constructor_index, bitsize_one_node);
6712
6713           if (! value)
6714             /* If we are doing the bookkeeping for an element that was
6715                directly output as a constructor, we must update
6716                constructor_unfilled_index.  */
6717             constructor_unfilled_index = constructor_index;
6718         }
6719
6720       /* Handle the sole element allowed in a braced initializer
6721          for a scalar variable.  */
6722       else if (constructor_fields == 0)
6723         {
6724           pedwarn_init ("excess elements in scalar initializer");
6725           break;
6726         }
6727       else
6728         {
6729           if (value)
6730             output_init_element (value, constructor_type, NULL_TREE, 1);
6731           constructor_fields = 0;
6732         }
6733
6734       /* Handle range initializers either at this level or anywhere higher
6735          in the designator stack.  */
6736       if (constructor_range_stack)
6737         {
6738           struct constructor_range_stack *p, *range_stack;
6739           int finish = 0;
6740
6741           range_stack = constructor_range_stack;
6742           constructor_range_stack = 0;
6743           while (constructor_stack != range_stack->stack)
6744             {
6745               if (!constructor_stack->implicit)
6746                 abort ();
6747               process_init_element (pop_init_level (1));
6748             }
6749           for (p = range_stack;
6750                !p->range_end || tree_int_cst_equal (p->index, p->range_end);
6751                p = p->prev)
6752             {
6753               if (!constructor_stack->implicit)
6754                 abort ();
6755               process_init_element (pop_init_level (1));
6756             }
6757
6758           p->index = size_binop (PLUS_EXPR, p->index, bitsize_one_node);
6759           if (tree_int_cst_equal (p->index, p->range_end) && !p->prev)
6760             finish = 1;
6761
6762           while (1)
6763             {
6764               constructor_index = p->index;
6765               constructor_fields = p->fields;
6766               if (finish && p->range_end && p->index == p->range_start)
6767                 {
6768                   finish = 0;
6769                   p->prev = 0;
6770                 }
6771               p = p->next;
6772               if (!p)
6773                 break;
6774               push_init_level (2);
6775               p->stack = constructor_stack;
6776               if (p->range_end && tree_int_cst_equal (p->index, p->range_end))
6777                 p->index = p->range_start;
6778             }
6779
6780           if (!finish)
6781             constructor_range_stack = range_stack;
6782           continue;
6783         }
6784
6785       break;
6786     }
6787
6788   constructor_range_stack = 0;
6789 }
6790 \f
6791 /* Build a simple asm-statement, from one string literal.  */
6792 tree
6793 simple_asm_stmt (expr)
6794      tree expr;
6795 {
6796   STRIP_NOPS (expr);
6797
6798   if (TREE_CODE (expr) == ADDR_EXPR)
6799     expr = TREE_OPERAND (expr, 0);
6800
6801   if (TREE_CODE (expr) == STRING_CST)
6802     {
6803       tree stmt;
6804
6805       if (TREE_CHAIN (expr))
6806         expr = combine_strings (expr);
6807       stmt = add_stmt (build_stmt (ASM_STMT, NULL_TREE, expr,
6808                                    NULL_TREE, NULL_TREE,
6809                                    NULL_TREE));
6810       ASM_INPUT_P (stmt) = 1;
6811       return stmt;
6812     }
6813
6814   error ("argument of `asm' is not a constant string");
6815   return NULL_TREE;
6816 }
6817
6818 /* Build an asm-statement, whose components are a CV_QUALIFIER, a
6819    STRING, some OUTPUTS, some INPUTS, and some CLOBBERS.  */
6820
6821 tree
6822 build_asm_stmt (cv_qualifier, string, outputs, inputs, clobbers)
6823      tree cv_qualifier;
6824      tree string;
6825      tree outputs;
6826      tree inputs;
6827      tree clobbers;
6828 {
6829   tree tail;
6830
6831   if (TREE_CHAIN (string))
6832     string = combine_strings (string);
6833   if (TREE_CODE (string) != STRING_CST)
6834     {
6835       error ("asm template is not a string constant");
6836       return NULL_TREE;
6837     }
6838
6839   if (cv_qualifier != NULL_TREE
6840       && cv_qualifier != ridpointers[(int) RID_VOLATILE])
6841     {
6842       warning ("%s qualifier ignored on asm",
6843                IDENTIFIER_POINTER (cv_qualifier));
6844       cv_qualifier = NULL_TREE;
6845     }
6846
6847   /* We can remove output conversions that change the type,
6848      but not the mode.  */
6849   for (tail = outputs; tail; tail = TREE_CHAIN (tail))
6850     {
6851       tree output = TREE_VALUE (tail);
6852
6853       STRIP_NOPS (output);
6854       TREE_VALUE (tail) = output;
6855
6856       /* Allow conversions as LHS here.  build_modify_expr as called below
6857          will do the right thing with them.  */
6858       while (TREE_CODE (output) == NOP_EXPR
6859              || TREE_CODE (output) == CONVERT_EXPR
6860              || TREE_CODE (output) == FLOAT_EXPR
6861              || TREE_CODE (output) == FIX_TRUNC_EXPR
6862              || TREE_CODE (output) == FIX_FLOOR_EXPR
6863              || TREE_CODE (output) == FIX_ROUND_EXPR
6864              || TREE_CODE (output) == FIX_CEIL_EXPR)
6865         output = TREE_OPERAND (output, 0);
6866
6867       lvalue_or_else (TREE_VALUE (tail), "invalid lvalue in asm statement");
6868     }
6869
6870   /* Remove output conversions that change the type but not the mode.  */
6871   for (tail = outputs; tail; tail = TREE_CHAIN (tail))
6872     {
6873       tree output = TREE_VALUE (tail);
6874       STRIP_NOPS (output);
6875       TREE_VALUE (tail) = output;
6876     }
6877
6878   /* Perform default conversions on array and function inputs.
6879      Don't do this for other types as it would screw up operands
6880      expected to be in memory.  */
6881   for (tail = inputs; tail; tail = TREE_CHAIN (tail))
6882     if (TREE_CODE (TREE_TYPE (TREE_VALUE (tail))) == ARRAY_TYPE
6883         || TREE_CODE (TREE_TYPE (TREE_VALUE (tail))) == FUNCTION_TYPE)
6884       TREE_VALUE (tail) = default_conversion (TREE_VALUE (tail));
6885
6886   return add_stmt (build_stmt (ASM_STMT, cv_qualifier, string,
6887                                outputs, inputs, clobbers));
6888 }
6889
6890 /* Expand an ASM statement with operands, handling output operands
6891    that are not variables or INDIRECT_REFS by transforming such
6892    cases into cases that expand_asm_operands can handle.
6893
6894    Arguments are same as for expand_asm_operands.  */
6895
6896 void
6897 c_expand_asm_operands (string, outputs, inputs, clobbers, vol, filename, line)
6898      tree string, outputs, inputs, clobbers;
6899      int vol;
6900      const char *filename;
6901      int line;
6902 {
6903   int noutputs = list_length (outputs);
6904   register int i;
6905   /* o[I] is the place that output number I should be written.  */
6906   register tree *o = (tree *) alloca (noutputs * sizeof (tree));
6907   register tree tail;
6908
6909   /* Record the contents of OUTPUTS before it is modified.  */
6910   for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
6911     o[i] = TREE_VALUE (tail);
6912
6913   /* Generate the ASM_OPERANDS insn; store into the TREE_VALUEs of
6914      OUTPUTS some trees for where the values were actually stored.  */
6915   expand_asm_operands (string, outputs, inputs, clobbers, vol, filename, line);
6916
6917   /* Copy all the intermediate outputs into the specified outputs.  */
6918   for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
6919     {
6920       if (o[i] != TREE_VALUE (tail))
6921         {
6922           expand_expr (build_modify_expr (o[i], NOP_EXPR, TREE_VALUE (tail)),
6923                        NULL_RTX, VOIDmode, EXPAND_NORMAL);
6924           free_temp_slots ();
6925
6926           /* Restore the original value so that it's correct the next
6927              time we expand this function.  */
6928           TREE_VALUE (tail) = o[i];
6929         }
6930       /* Detect modification of read-only values.
6931          (Otherwise done by build_modify_expr.)  */
6932       else
6933         {
6934           tree type = TREE_TYPE (o[i]);
6935           if (TREE_READONLY (o[i])
6936               || TYPE_READONLY (type)
6937               || ((TREE_CODE (type) == RECORD_TYPE
6938                    || TREE_CODE (type) == UNION_TYPE)
6939                   && C_TYPE_FIELDS_READONLY (type)))
6940             readonly_warning (o[i], "modification by `asm'");
6941         }
6942     }
6943
6944   /* Those MODIFY_EXPRs could do autoincrements.  */
6945   emit_queue ();
6946 }
6947 \f
6948 /* Expand a C `return' statement.
6949    RETVAL is the expression for what to return,
6950    or a null pointer for `return;' with no value.  */
6951
6952 tree
6953 c_expand_return (retval)
6954      tree retval;
6955 {
6956   tree valtype = TREE_TYPE (TREE_TYPE (current_function_decl));
6957
6958   if (TREE_THIS_VOLATILE (current_function_decl))
6959     warning ("function declared `noreturn' has a `return' statement");
6960
6961   if (!retval)
6962     {
6963       current_function_returns_null = 1;
6964       if ((warn_return_type || flag_isoc99)
6965           && valtype != 0 && TREE_CODE (valtype) != VOID_TYPE)
6966         pedwarn_c99 ("`return' with no value, in function returning non-void");
6967     }
6968   else if (valtype == 0 || TREE_CODE (valtype) == VOID_TYPE)
6969     {
6970       current_function_returns_null = 1;
6971       if (pedantic || TREE_CODE (TREE_TYPE (retval)) != VOID_TYPE)
6972         pedwarn ("`return' with a value, in function returning void");
6973     }
6974   else
6975     {
6976       tree t = convert_for_assignment (valtype, retval, _("return"),
6977                                        NULL_TREE, NULL_TREE, 0);
6978       tree res = DECL_RESULT (current_function_decl);
6979       tree inner;
6980
6981       if (t == error_mark_node)
6982         return NULL_TREE;
6983
6984       inner = t = convert (TREE_TYPE (res), t);
6985
6986       /* Strip any conversions, additions, and subtractions, and see if
6987          we are returning the address of a local variable.  Warn if so.  */
6988       while (1)
6989         {
6990           switch (TREE_CODE (inner))
6991             {
6992             case NOP_EXPR:   case NON_LVALUE_EXPR:  case CONVERT_EXPR:
6993             case PLUS_EXPR:
6994               inner = TREE_OPERAND (inner, 0);
6995               continue;
6996
6997             case MINUS_EXPR:
6998               /* If the second operand of the MINUS_EXPR has a pointer
6999                  type (or is converted from it), this may be valid, so
7000                  don't give a warning.  */
7001               {
7002                 tree op1 = TREE_OPERAND (inner, 1);
7003
7004                 while (! POINTER_TYPE_P (TREE_TYPE (op1))
7005                        && (TREE_CODE (op1) == NOP_EXPR
7006                            || TREE_CODE (op1) == NON_LVALUE_EXPR
7007                            || TREE_CODE (op1) == CONVERT_EXPR))
7008                   op1 = TREE_OPERAND (op1, 0);
7009
7010                 if (POINTER_TYPE_P (TREE_TYPE (op1)))
7011                   break;
7012
7013                 inner = TREE_OPERAND (inner, 0);
7014                 continue;
7015               }
7016
7017             case ADDR_EXPR:
7018               inner = TREE_OPERAND (inner, 0);
7019
7020               while (TREE_CODE_CLASS (TREE_CODE (inner)) == 'r')
7021                 inner = TREE_OPERAND (inner, 0);
7022
7023               if (TREE_CODE (inner) == VAR_DECL
7024                   && ! DECL_EXTERNAL (inner)
7025                   && ! TREE_STATIC (inner)
7026                   && DECL_CONTEXT (inner) == current_function_decl)
7027                 warning ("function returns address of local variable");
7028               break;
7029
7030             default:
7031               break;
7032             }
7033
7034           break;
7035         }
7036
7037       retval = build (MODIFY_EXPR, TREE_TYPE (res), res, t);
7038       current_function_returns_value = 1;
7039     }
7040
7041  return add_stmt (build_return_stmt (retval));
7042 }
7043 \f
7044 struct c_switch {
7045   /* The SWITCH_STMT being built.  */
7046   tree switch_stmt;
7047   /* A splay-tree mapping the low element of a case range to the high
7048      element, or NULL_TREE if there is no high element.  Used to
7049      determine whether or not a new case label duplicates an old case
7050      label.  We need a tree, rather than simply a hash table, because
7051      of the GNU case range extension.  */
7052   splay_tree cases;
7053   /* The next node on the stack.  */
7054   struct c_switch *next;
7055 };
7056
7057 /* A stack of the currently active switch statements.  The innermost
7058    switch statement is on the top of the stack.  There is no need to
7059    mark the stack for garbage collection because it is only active
7060    during the processing of the body of a function, and we never
7061    collect at that point.  */
7062
7063 static struct c_switch *switch_stack;
7064
7065 /* Start a C switch statement, testing expression EXP.  Return the new
7066    SWITCH_STMT.  */
7067
7068 tree
7069 c_start_case (exp)
7070      tree exp;
7071 {
7072   register enum tree_code code;
7073   tree type;
7074   struct c_switch *cs;
7075
7076   if (exp != error_mark_node)
7077     {
7078       code = TREE_CODE (TREE_TYPE (exp));
7079       type = TREE_TYPE (exp);
7080
7081       if (code != INTEGER_TYPE
7082           && code != ENUMERAL_TYPE
7083           && code != ERROR_MARK)
7084         {
7085           error ("switch quantity not an integer");
7086           exp = integer_zero_node;
7087         }
7088       else
7089         {
7090           tree index;
7091           type = TYPE_MAIN_VARIANT (TREE_TYPE (exp));
7092
7093           if (warn_traditional && !in_system_header
7094               && (type == long_integer_type_node
7095                   || type == long_unsigned_type_node))
7096             warning ("`long' switch expression not converted to `int' in ISO C");
7097
7098           exp = default_conversion (exp);
7099           type = TREE_TYPE (exp);
7100           index = get_unwidened (exp, NULL_TREE);
7101           /* We can't strip a conversion from a signed type to an
7102              unsigned, because if we did, int_fits_type_p would do the
7103              wrong thing when checking case values for being in range,
7104              and it's too hard to do the right thing.  */
7105           if (TREE_UNSIGNED (TREE_TYPE (exp))
7106               == TREE_UNSIGNED (TREE_TYPE (index)))
7107             exp = index;
7108         }
7109     }
7110
7111   /* Add this new SWITCH_STMT to the stack.  */
7112   cs = (struct c_switch *) xmalloc (sizeof (*cs));
7113   cs->switch_stmt = build_stmt (SWITCH_STMT, exp, NULL_TREE, NULL_TREE);
7114   cs->cases = splay_tree_new (case_compare, NULL, NULL);
7115   cs->next = switch_stack;
7116   switch_stack = cs;
7117
7118   return add_stmt (switch_stack->switch_stmt);
7119 }
7120
7121 /* Process a case label.  */
7122
7123 tree
7124 do_case (low_value, high_value)
7125      tree low_value;
7126      tree high_value;
7127 {
7128   tree label = NULL_TREE;
7129
7130   if (switch_stack)
7131     {
7132       label = c_add_case_label (switch_stack->cases,
7133                                 SWITCH_COND (switch_stack->switch_stmt),
7134                                 low_value, high_value);
7135       if (label == error_mark_node)
7136         label = NULL_TREE;
7137     }
7138   else if (low_value)
7139     error ("case label not within a switch statement");
7140   else
7141     error ("`default' label not within a switch statement");
7142
7143   return label;
7144 }
7145
7146 /* Finish the switch statement.  */
7147
7148 void
7149 c_finish_case ()
7150 {
7151   struct c_switch *cs = switch_stack;
7152
7153   RECHAIN_STMTS (cs->switch_stmt, SWITCH_BODY (cs->switch_stmt));
7154
7155   /* Pop the stack.  */
7156   switch_stack = switch_stack->next;
7157   splay_tree_delete (cs->cases);
7158   free (cs);
7159 }