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