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, 1998,
   3    1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20 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 #include "config.h"
  29 #include "system.h"
  30 #include "coretypes.h"
  31 #include "tm.h"
  32 #include "rtl.h"
  33 #include "tree.h"
  34 #include "langhooks.h"
  35 #include "c-tree.h"
  36 #include "tm_p.h"
  37 #include "flags.h"
  38 #include "output.h"
  39 #include "expr.h"
  40 #include "toplev.h"
  41 #include "intl.h"
  42 #include "ggc.h"
  43 #include "target.h"
  44 #include "tree-iterator.h"
  45 #include "tree-gimple.h"
  46 #include "tree-flow.h"
  47
  48 /* Possible cases of implicit bad conversions.  Used to select
  49    diagnostic messages in convert_for_assignment.  */
  50 enum impl_conv {
  51   ic_argpass,
  52   ic_argpass_nonproto,
  53   ic_assign,
  54   ic_init,
  55   ic_return
  56 };
  57
  58 /* The level of nesting inside "__alignof__".  */
  59 int in_alignof;
  60
  61 /* The level of nesting inside "sizeof".  */
  62 int in_sizeof;
  63
  64 /* The level of nesting inside "typeof".  */
  65 int in_typeof;
  66
  67 struct c_label_context_se *label_context_stack_se;
  68 struct c_label_context_vm *label_context_stack_vm;
  69
  70 /* Nonzero if we've already printed a "missing braces around initializer"
  71    message within this initializer.  */
  72 static int missing_braces_mentioned;
  73
  74 static int require_constant_value;
  75 static int require_constant_elements;
  76
  77 static tree qualify_type (tree, tree);
  78 static int tagged_types_tu_compatible_p (tree, tree);
  79 static int comp_target_types (tree, tree, int);
  80 static int function_types_compatible_p (tree, tree);
  81 static int type_lists_compatible_p (tree, tree);
  82 static tree decl_constant_value_for_broken_optimization (tree);
  83 static tree default_function_array_conversion (tree);
  84 static tree lookup_field (tree, tree);
  85 static tree convert_arguments (tree, tree, tree, tree);
  86 static tree pointer_diff (tree, tree);
  87 static tree convert_for_assignment (tree, tree, enum impl_conv, tree, tree,
  88                                     int);
  89 static tree valid_compound_expr_initializer (tree, tree);
  90 static void push_string (const char *);
  91 static void push_member_name (tree);
  92 static void push_array_bounds (int);
  93 static int spelling_length (void);
  94 static char *print_spelling (char *);
  95 static void warning_init (const char *);
  96 static tree digest_init (tree, tree, bool, int);
  97 static void output_init_element (tree, bool, tree, tree, int);
  98 static void output_pending_init_elements (int);
  99 static int set_designator (int);
 100 static void push_range_stack (tree);
 101 static void add_pending_init (tree, tree);
 102 static void set_nonincremental_init (void);
 103 static void set_nonincremental_init_from_string (tree);
 104 static tree find_init_member (tree);
 105 static void readonly_error (tree, enum lvalue_use);
 106 static int lvalue_or_else (tree, enum lvalue_use);
 107 static int lvalue_p (tree);
 108 static void record_maybe_used_decl (tree);
 109 \f
 110 /* Do `exp = require_complete_type (exp);' to make sure exp
 111    does not have an incomplete type.  (That includes void types.)  */
 112
 113 tree
 114 require_complete_type (tree value)
 115 {
 116   tree type = TREE_TYPE (value);
 117
 118   if (value == error_mark_node || type == error_mark_node)
 119     return error_mark_node;
 120
 121   /* First, detect a valid value with a complete type.  */
 122   if (COMPLETE_TYPE_P (type))
 123     return value;
 124
 125   c_incomplete_type_error (value, type);
 126   return error_mark_node;
 127 }
 128
 129 /* Print an error message for invalid use of an incomplete type.
 130    VALUE is the expression that was used (or 0 if that isn't known)
 131    and TYPE is the type that was invalid.  */
 132
 133 void
 134 c_incomplete_type_error (tree value, tree type)
 135 {
 136   const char *type_code_string;
 137
 138   /* Avoid duplicate error message.  */
 139   if (TREE_CODE (type) == ERROR_MARK)
 140     return;
 141
 142   if (value != 0 && (TREE_CODE (value) == VAR_DECL
 143                      || TREE_CODE (value) == PARM_DECL))
 144     error ("%qD has an incomplete type", value);
 145   else
 146     {
 147     retry:
 148       /* We must print an error message.  Be clever about what it says.  */
 149
 150       switch (TREE_CODE (type))
 151         {
 152         case RECORD_TYPE:
 153           type_code_string = "struct";
 154           break;
 155
 156         case UNION_TYPE:
 157           type_code_string = "union";
 158           break;
 159
 160         case ENUMERAL_TYPE:
 161           type_code_string = "enum";
 162           break;
 163
 164         case VOID_TYPE:
 165           error ("invalid use of void expression");
 166           return;
 167
 168         case ARRAY_TYPE:
 169           if (TYPE_DOMAIN (type))
 170             {
 171               if (TYPE_MAX_VALUE (TYPE_DOMAIN (type)) == NULL)
 172                 {
 173                   error ("invalid use of flexible array member");
 174                   return;
 175                 }
 176               type = TREE_TYPE (type);
 177               goto retry;
 178             }
 179           error ("invalid use of array with unspecified bounds");
 180           return;
 181
 182         default:
 183           gcc_unreachable ();
 184         }
 185
 186       if (TREE_CODE (TYPE_NAME (type)) == IDENTIFIER_NODE)
 187         error ("invalid use of undefined type %<%s %E%>",
 188                type_code_string, TYPE_NAME (type));
 189       else
 190         /* If this type has a typedef-name, the TYPE_NAME is a TYPE_DECL.  */
 191         error ("invalid use of incomplete typedef %qD", TYPE_NAME (type));
 192     }
 193 }
 194
 195 /* Given a type, apply default promotions wrt unnamed function
 196    arguments and return the new type.  */
 197
 198 tree
 199 c_type_promotes_to (tree type)
 200 {
 201   if (TYPE_MAIN_VARIANT (type) == float_type_node)
 202     return double_type_node;
 203
 204   if (c_promoting_integer_type_p (type))
 205     {
 206       /* Preserve unsignedness if not really getting any wider.  */
 207       if (TYPE_UNSIGNED (type)
 208           && (TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node)))
 209         return unsigned_type_node;
 210       return integer_type_node;
 211     }
 212
 213   return type;
 214 }
 215
 216 /* Return a variant of TYPE which has all the type qualifiers of LIKE
 217    as well as those of TYPE.  */
 218
 219 static tree
 220 qualify_type (tree type, tree like)
 221 {
 222   return c_build_qualified_type (type,
 223                                  TYPE_QUALS (type) | TYPE_QUALS (like));
 224 }
 225 \f
 226 /* Return the composite type of two compatible types.
 227
 228    We assume that comptypes has already been done and returned
 229    nonzero; if that isn't so, this may crash.  In particular, we
 230    assume that qualifiers match.  */
 231
 232 tree
 233 composite_type (tree t1, tree t2)
 234 {
 235   enum tree_code code1;
 236   enum tree_code code2;
 237   tree attributes;
 238
 239   /* Save time if the two types are the same.  */
 240
 241   if (t1 == t2) return t1;
 242
 243   /* If one type is nonsense, use the other.  */
 244   if (t1 == error_mark_node)
 245     return t2;
 246   if (t2 == error_mark_node)
 247     return t1;
 248
 249   code1 = TREE_CODE (t1);
 250   code2 = TREE_CODE (t2);
 251
 252   /* Merge the attributes.  */
 253   attributes = targetm.merge_type_attributes (t1, t2);
 254
 255   /* If one is an enumerated type and the other is the compatible
 256      integer type, the composite type might be either of the two
 257      (DR#013 question 3).  For consistency, use the enumerated type as
 258      the composite type.  */
 259
 260   if (code1 == ENUMERAL_TYPE && code2 == INTEGER_TYPE)
 261     return t1;
 262   if (code2 == ENUMERAL_TYPE && code1 == INTEGER_TYPE)
 263     return t2;
 264
 265   gcc_assert (code1 == code2);
 266
 267   switch (code1)
 268     {
 269     case POINTER_TYPE:
 270       /* For two pointers, do this recursively on the target type.  */
 271       {
 272         tree pointed_to_1 = TREE_TYPE (t1);
 273         tree pointed_to_2 = TREE_TYPE (t2);
 274         tree target = composite_type (pointed_to_1, pointed_to_2);
 275         t1 = build_pointer_type (target);
 276         t1 = build_type_attribute_variant (t1, attributes);
 277         return qualify_type (t1, t2);
 278       }
 279
 280     case ARRAY_TYPE:
 281       {
 282         tree elt = composite_type (TREE_TYPE (t1), TREE_TYPE (t2));
 283         int quals;
 284         tree unqual_elt;
 285
 286         /* We should not have any type quals on arrays at all.  */
 287         gcc_assert (!TYPE_QUALS (t1) && !TYPE_QUALS (t2));
 288
 289         /* Save space: see if the result is identical to one of the args.  */
 290         if (elt == TREE_TYPE (t1) && TYPE_DOMAIN (t1))
 291           return build_type_attribute_variant (t1, attributes);
 292         if (elt == TREE_TYPE (t2) && TYPE_DOMAIN (t2))
 293           return build_type_attribute_variant (t2, attributes);
 294
 295         if (elt == TREE_TYPE (t1) && !TYPE_DOMAIN (t2) && !TYPE_DOMAIN (t1))
 296           return build_type_attribute_variant (t1, attributes);
 297         if (elt == TREE_TYPE (t2) && !TYPE_DOMAIN (t2) && !TYPE_DOMAIN (t1))
 298           return build_type_attribute_variant (t2, attributes);
 299
 300         /* Merge the element types, and have a size if either arg has
 301            one.  We may have qualifiers on the element types.  To set
 302            up TYPE_MAIN_VARIANT correctly, we need to form the
 303            composite of the unqualified types and add the qualifiers
 304            back at the end.  */
 305         quals = TYPE_QUALS (strip_array_types (elt));
 306         unqual_elt = c_build_qualified_type (elt, TYPE_UNQUALIFIED);
 307         t1 = build_array_type (unqual_elt,
 308                                TYPE_DOMAIN (TYPE_DOMAIN (t1) ? t1 : t2));
 309         t1 = c_build_qualified_type (t1, quals);
 310         return build_type_attribute_variant (t1, attributes);
 311       }
 312
 313     case FUNCTION_TYPE:
 314       /* Function types: prefer the one that specified arg types.
 315          If both do, merge the arg types.  Also merge the return types.  */
 316       {
 317         tree valtype = composite_type (TREE_TYPE (t1), TREE_TYPE (t2));
 318         tree p1 = TYPE_ARG_TYPES (t1);
 319         tree p2 = TYPE_ARG_TYPES (t2);
 320         int len;
 321         tree newargs, n;
 322         int i;
 323
 324         /* Save space: see if the result is identical to one of the args.  */
 325         if (valtype == TREE_TYPE (t1) && !TYPE_ARG_TYPES (t2))
 326           return build_type_attribute_variant (t1, attributes);
 327         if (valtype == TREE_TYPE (t2) && !TYPE_ARG_TYPES (t1))
 328           return build_type_attribute_variant (t2, attributes);
 329
 330         /* Simple way if one arg fails to specify argument types.  */
 331         if (TYPE_ARG_TYPES (t1) == 0)
 332          {
 333             t1 = build_function_type (valtype, TYPE_ARG_TYPES (t2));
 334             t1 = build_type_attribute_variant (t1, attributes);
 335             return qualify_type (t1, t2);
 336          }
 337         if (TYPE_ARG_TYPES (t2) == 0)
 338          {
 339            t1 = build_function_type (valtype, TYPE_ARG_TYPES (t1));
 340            t1 = build_type_attribute_variant (t1, attributes);
 341            return qualify_type (t1, t2);
 342          }
 343
 344         /* If both args specify argument types, we must merge the two
 345            lists, argument by argument.  */
 346         /* Tell global_bindings_p to return false so that variable_size
 347            doesn't die on VLAs in parameter types.  */
 348         c_override_global_bindings_to_false = true;
 349
 350         len = list_length (p1);
 351         newargs = 0;
 352
 353         for (i = 0; i < len; i++)
 354           newargs = tree_cons (NULL_TREE, NULL_TREE, newargs);
 355
 356         n = newargs;
 357
 358         for (; p1;
 359              p1 = TREE_CHAIN (p1), p2 = TREE_CHAIN (p2), n = TREE_CHAIN (n))
 360           {
 361             /* A null type means arg type is not specified.
 362                Take whatever the other function type has.  */
 363             if (TREE_VALUE (p1) == 0)
 364               {
 365                 TREE_VALUE (n) = TREE_VALUE (p2);
 366                 goto parm_done;
 367               }
 368             if (TREE_VALUE (p2) == 0)
 369               {
 370                 TREE_VALUE (n) = TREE_VALUE (p1);
 371                 goto parm_done;
 372               }
 373
 374             /* Given  wait (union {union wait *u; int *i} *)
 375                and  wait (union wait *),
 376                prefer  union wait *  as type of parm.  */
 377             if (TREE_CODE (TREE_VALUE (p1)) == UNION_TYPE
 378                 && TREE_VALUE (p1) != TREE_VALUE (p2))
 379               {
 380                 tree memb;
 381                 tree mv2 = TREE_VALUE (p2);
 382                 if (mv2 && mv2 != error_mark_node
 383                     && TREE_CODE (mv2) != ARRAY_TYPE)
 384                   mv2 = TYPE_MAIN_VARIANT (mv2);
 385                 for (memb = TYPE_FIELDS (TREE_VALUE (p1));
 386                      memb; memb = TREE_CHAIN (memb))
 387                   {
 388                     tree mv3 = TREE_TYPE (memb);
 389                     if (mv3 && mv3 != error_mark_node
 390                         && TREE_CODE (mv3) != ARRAY_TYPE)
 391                       mv3 = TYPE_MAIN_VARIANT (mv3);
 392                     if (comptypes (mv3, mv2))
 393                       {
 394                         TREE_VALUE (n) = composite_type (TREE_TYPE (memb),
 395                                                          TREE_VALUE (p2));
 396                         if (pedantic)
 397                           pedwarn ("function types not truly compatible in ISO C");
 398                         goto parm_done;
 399                       }
 400                   }
 401               }
 402             if (TREE_CODE (TREE_VALUE (p2)) == UNION_TYPE
 403                 && TREE_VALUE (p2) != TREE_VALUE (p1))
 404               {
 405                 tree memb;
 406                 tree mv1 = TREE_VALUE (p1);
 407                 if (mv1 && mv1 != error_mark_node
 408                     && TREE_CODE (mv1) != ARRAY_TYPE)
 409                   mv1 = TYPE_MAIN_VARIANT (mv1);
 410                 for (memb = TYPE_FIELDS (TREE_VALUE (p2));
 411                      memb; memb = TREE_CHAIN (memb))
 412                   {
 413                     tree mv3 = TREE_TYPE (memb);
 414                     if (mv3 && mv3 != error_mark_node
 415                         && TREE_CODE (mv3) != ARRAY_TYPE)
 416                       mv3 = TYPE_MAIN_VARIANT (mv3);
 417                     if (comptypes (mv3, mv1))
 418                       {
 419                         TREE_VALUE (n) = composite_type (TREE_TYPE (memb),
 420                                                          TREE_VALUE (p1));
 421                         if (pedantic)
 422                           pedwarn ("function types not truly compatible in ISO C");
 423                         goto parm_done;
 424                       }
 425                   }
 426               }
 427             TREE_VALUE (n) = composite_type (TREE_VALUE (p1), TREE_VALUE (p2));
 428           parm_done: ;
 429           }
 430
 431         c_override_global_bindings_to_false = false;
 432         t1 = build_function_type (valtype, newargs);
 433         t1 = qualify_type (t1, t2);
 434         /* ... falls through ...  */
 435       }
 436
 437     default:
 438       return build_type_attribute_variant (t1, attributes);
 439     }
 440
 441 }
 442
 443 /* Return the type of a conditional expression between pointers to
 444    possibly differently qualified versions of compatible types.
 445
 446    We assume that comp_target_types has already been done and returned
 447    nonzero; if that isn't so, this may crash.  */
 448
 449 static tree
 450 common_pointer_type (tree t1, tree t2)
 451 {
 452   tree attributes;
 453   tree pointed_to_1, mv1;
 454   tree pointed_to_2, mv2;
 455   tree target;
 456
 457   /* Save time if the two types are the same.  */
 458
 459   if (t1 == t2) return t1;
 460
 461   /* If one type is nonsense, use the other.  */
 462   if (t1 == error_mark_node)
 463     return t2;
 464   if (t2 == error_mark_node)
 465     return t1;
 466
 467   gcc_assert (TREE_CODE (t1) == POINTER_TYPE
 468               && TREE_CODE (t2) == POINTER_TYPE);
 469
 470   /* Merge the attributes.  */
 471   attributes = targetm.merge_type_attributes (t1, t2);
 472
 473   /* Find the composite type of the target types, and combine the
 474      qualifiers of the two types' targets.  Do not lose qualifiers on
 475      array element types by taking the TYPE_MAIN_VARIANT.  */
 476   mv1 = pointed_to_1 = TREE_TYPE (t1);
 477   mv2 = pointed_to_2 = TREE_TYPE (t2);
 478   if (TREE_CODE (mv1) != ARRAY_TYPE)
 479     mv1 = TYPE_MAIN_VARIANT (pointed_to_1);
 480   if (TREE_CODE (mv2) != ARRAY_TYPE)
 481     mv2 = TYPE_MAIN_VARIANT (pointed_to_2);
 482   target = composite_type (mv1, mv2);
 483   t1 = build_pointer_type (c_build_qualified_type
 484                            (target,
 485                             TYPE_QUALS (pointed_to_1) |
 486                             TYPE_QUALS (pointed_to_2)));
 487   return build_type_attribute_variant (t1, attributes);
 488 }
 489
 490 /* Return the common type for two arithmetic types under the usual
 491    arithmetic conversions.  The default conversions have already been
 492    applied, and enumerated types converted to their compatible integer
 493    types.  The resulting type is unqualified and has no attributes.
 494
 495    This is the type for the result of most arithmetic operations
 496    if the operands have the given two types.  */
 497
 498 static tree
 499 c_common_type (tree t1, tree t2)
 500 {
 501   enum tree_code code1;
 502   enum tree_code code2;
 503
 504   /* If one type is nonsense, use the other.  */
 505   if (t1 == error_mark_node)
 506     return t2;
 507   if (t2 == error_mark_node)
 508     return t1;
 509
 510   if (TYPE_QUALS (t1) != TYPE_UNQUALIFIED)
 511     t1 = TYPE_MAIN_VARIANT (t1);
 512
 513   if (TYPE_QUALS (t2) != TYPE_UNQUALIFIED)
 514     t2 = TYPE_MAIN_VARIANT (t2);
 515
 516   if (TYPE_ATTRIBUTES (t1) != NULL_TREE)
 517     t1 = build_type_attribute_variant (t1, NULL_TREE);
 518
 519   if (TYPE_ATTRIBUTES (t2) != NULL_TREE)
 520     t2 = build_type_attribute_variant (t2, NULL_TREE);
 521
 522   /* Save time if the two types are the same.  */
 523
 524   if (t1 == t2) return t1;
 525
 526   code1 = TREE_CODE (t1);
 527   code2 = TREE_CODE (t2);
 528
 529   gcc_assert (code1 == VECTOR_TYPE || code1 == COMPLEX_TYPE
 530               || code1 == REAL_TYPE || code1 == INTEGER_TYPE);
 531   gcc_assert (code2 == VECTOR_TYPE || code2 == COMPLEX_TYPE
 532               || code2 == REAL_TYPE || code2 == INTEGER_TYPE);
 533
 534   /* If one type is a vector type, return that type.  (How the usual
 535      arithmetic conversions apply to the vector types extension is not
 536      precisely specified.)  */
 537   if (code1 == VECTOR_TYPE)
 538     return t1;
 539
 540   if (code2 == VECTOR_TYPE)
 541     return t2;
 542
 543   /* If one type is complex, form the common type of the non-complex
 544      components, then make that complex.  Use T1 or T2 if it is the
 545      required type.  */
 546   if (code1 == COMPLEX_TYPE || code2 == COMPLEX_TYPE)
 547     {
 548       tree subtype1 = code1 == COMPLEX_TYPE ? TREE_TYPE (t1) : t1;
 549       tree subtype2 = code2 == COMPLEX_TYPE ? TREE_TYPE (t2) : t2;
 550       tree subtype = c_common_type (subtype1, subtype2);
 551
 552       if (code1 == COMPLEX_TYPE && TREE_TYPE (t1) == subtype)
 553         return t1;
 554       else if (code2 == COMPLEX_TYPE && TREE_TYPE (t2) == subtype)
 555         return t2;
 556       else
 557         return build_complex_type (subtype);
 558     }
 559
 560   /* If only one is real, use it as the result.  */
 561
 562   if (code1 == REAL_TYPE && code2 != REAL_TYPE)
 563     return t1;
 564
 565   if (code2 == REAL_TYPE && code1 != REAL_TYPE)
 566     return t2;
 567
 568   /* Both real or both integers; use the one with greater precision.  */
 569
 570   if (TYPE_PRECISION (t1) > TYPE_PRECISION (t2))
 571     return t1;
 572   else if (TYPE_PRECISION (t2) > TYPE_PRECISION (t1))
 573     return t2;
 574
 575   /* Same precision.  Prefer long longs to longs to ints when the
 576      same precision, following the C99 rules on integer type rank
 577      (which are equivalent to the C90 rules for C90 types).  */
 578
 579   if (TYPE_MAIN_VARIANT (t1) == long_long_unsigned_type_node
 580       || TYPE_MAIN_VARIANT (t2) == long_long_unsigned_type_node)
 581     return long_long_unsigned_type_node;
 582
 583   if (TYPE_MAIN_VARIANT (t1) == long_long_integer_type_node
 584       || TYPE_MAIN_VARIANT (t2) == long_long_integer_type_node)
 585     {
 586       if (TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 587         return long_long_unsigned_type_node;
 588       else
 589         return long_long_integer_type_node;
 590     }
 591
 592   if (TYPE_MAIN_VARIANT (t1) == long_unsigned_type_node
 593       || TYPE_MAIN_VARIANT (t2) == long_unsigned_type_node)
 594     return long_unsigned_type_node;
 595
 596   if (TYPE_MAIN_VARIANT (t1) == long_integer_type_node
 597       || TYPE_MAIN_VARIANT (t2) == long_integer_type_node)
 598     {
 599       /* But preserve unsignedness from the other type,
 600          since long cannot hold all the values of an unsigned int.  */
 601       if (TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 602         return long_unsigned_type_node;
 603       else
 604         return long_integer_type_node;
 605     }
 606
 607   /* Likewise, prefer long double to double even if same size.  */
 608   if (TYPE_MAIN_VARIANT (t1) == long_double_type_node
 609       || TYPE_MAIN_VARIANT (t2) == long_double_type_node)
 610     return long_double_type_node;
 611
 612   /* Otherwise prefer the unsigned one.  */
 613
 614   if (TYPE_UNSIGNED (t1))
 615     return t1;
 616   else
 617     return t2;
 618 }
 619 \f
 620 /* Wrapper around c_common_type that is used by c-common.c.  ENUMERAL_TYPEs
 621    are allowed here and are converted to their compatible integer types.  */
 622 tree
 623 common_type (tree t1, tree t2)
 624 {
 625   if (TREE_CODE (t1) == ENUMERAL_TYPE)
 626     t1 = c_common_type_for_size (TYPE_PRECISION (t1), 1);
 627   if (TREE_CODE (t2) == ENUMERAL_TYPE)
 628     t2 = c_common_type_for_size (TYPE_PRECISION (t2), 1);
 629   return c_common_type (t1, t2);
 630 }
 631 \f
 632 /* Return 1 if TYPE1 and TYPE2 are compatible types for assignment
 633    or various other operations.  Return 2 if they are compatible
 634    but a warning may be needed if you use them together.  */
 635
 636 int
 637 comptypes (tree type1, tree type2)
 638 {
 639   tree t1 = type1;
 640   tree t2 = type2;
 641   int attrval, val;
 642
 643   /* Suppress errors caused by previously reported errors.  */
 644
 645   if (t1 == t2 || !t1 || !t2
 646       || TREE_CODE (t1) == ERROR_MARK || TREE_CODE (t2) == ERROR_MARK)
 647     return 1;
 648
 649   /* If either type is the internal version of sizetype, return the
 650      language version.  */
 651   if (TREE_CODE (t1) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t1)
 652       && TYPE_ORIG_SIZE_TYPE (t1))
 653     t1 = TYPE_ORIG_SIZE_TYPE (t1);
 654
 655   if (TREE_CODE (t2) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t2)
 656       && TYPE_ORIG_SIZE_TYPE (t2))
 657     t2 = TYPE_ORIG_SIZE_TYPE (t2);
 658
 659
 660   /* Enumerated types are compatible with integer types, but this is
 661      not transitive: two enumerated types in the same translation unit
 662      are compatible with each other only if they are the same type.  */
 663
 664   if (TREE_CODE (t1) == ENUMERAL_TYPE && TREE_CODE (t2) != ENUMERAL_TYPE)
 665     t1 = c_common_type_for_size (TYPE_PRECISION (t1), TYPE_UNSIGNED (t1));
 666   else if (TREE_CODE (t2) == ENUMERAL_TYPE && TREE_CODE (t1) != ENUMERAL_TYPE)
 667     t2 = c_common_type_for_size (TYPE_PRECISION (t2), TYPE_UNSIGNED (t2));
 668
 669   if (t1 == t2)
 670     return 1;
 671
 672   /* Different classes of types can't be compatible.  */
 673
 674   if (TREE_CODE (t1) != TREE_CODE (t2))
 675     return 0;
 676
 677   /* Qualifiers must match. C99 6.7.3p9 */
 678
 679   if (TYPE_QUALS (t1) != TYPE_QUALS (t2))
 680     return 0;
 681
 682   /* Allow for two different type nodes which have essentially the same
 683      definition.  Note that we already checked for equality of the type
 684      qualifiers (just above).  */
 685
 686   if (TREE_CODE (t1) != ARRAY_TYPE
 687       && TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
 688     return 1;
 689
 690   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
 691   if (!(attrval = targetm.comp_type_attributes (t1, t2)))
 692      return 0;
 693
 694   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
 695   val = 0;
 696
 697   switch (TREE_CODE (t1))
 698     {
 699     case POINTER_TYPE:
 700       /* We must give ObjC the first crack at comparing pointers, since
 701            protocol qualifiers may be involved.  */
 702       if (c_dialect_objc () && (val = objc_comptypes (t1, t2, 0)) >= 0)
 703         break;
 704       /* Do not remove mode or aliasing information.  */
 705       if (TYPE_MODE (t1) != TYPE_MODE (t2)
 706           || TYPE_REF_CAN_ALIAS_ALL (t1) != TYPE_REF_CAN_ALIAS_ALL (t2))
 707         break;
 708       val = (TREE_TYPE (t1) == TREE_TYPE (t2)
 709              ? 1 : comptypes (TREE_TYPE (t1), TREE_TYPE (t2)));
 710       break;
 711
 712     case FUNCTION_TYPE:
 713       val = function_types_compatible_p (t1, t2);
 714       break;
 715
 716     case ARRAY_TYPE:
 717       {
 718         tree d1 = TYPE_DOMAIN (t1);
 719         tree d2 = TYPE_DOMAIN (t2);
 720         bool d1_variable, d2_variable;
 721         bool d1_zero, d2_zero;
 722         val = 1;
 723
 724         /* Target types must match incl. qualifiers.  */
 725         if (TREE_TYPE (t1) != TREE_TYPE (t2)
 726             && 0 == (val = comptypes (TREE_TYPE (t1), TREE_TYPE (t2))))
 727           return 0;
 728
 729         /* Sizes must match unless one is missing or variable.  */
 730         if (d1 == 0 || d2 == 0 || d1 == d2)
 731           break;
 732
 733         d1_zero = !TYPE_MAX_VALUE (d1);
 734         d2_zero = !TYPE_MAX_VALUE (d2);
 735
 736         d1_variable = (!d1_zero
 737                        && (TREE_CODE (TYPE_MIN_VALUE (d1)) != INTEGER_CST
 738                            || TREE_CODE (TYPE_MAX_VALUE (d1)) != INTEGER_CST));
 739         d2_variable = (!d2_zero
 740                        && (TREE_CODE (TYPE_MIN_VALUE (d2)) != INTEGER_CST
 741                            || TREE_CODE (TYPE_MAX_VALUE (d2)) != INTEGER_CST));
 742
 743         if (d1_variable || d2_variable)
 744           break;
 745         if (d1_zero && d2_zero)
 746           break;
 747         if (d1_zero || d2_zero
 748             || !tree_int_cst_equal (TYPE_MIN_VALUE (d1), TYPE_MIN_VALUE (d2))
 749             || !tree_int_cst_equal (TYPE_MAX_VALUE (d1), TYPE_MAX_VALUE (d2)))
 750           val = 0;
 751
 752         break;
 753       }
 754
 755     case RECORD_TYPE:
 756       /* We are dealing with two distinct structs.  In assorted Objective-C
 757          corner cases, however, these can still be deemed equivalent.  */
 758       if (c_dialect_objc () && objc_comptypes (t1, t2, 0) == 1)
 759         val = 1;
 760
 761     case ENUMERAL_TYPE:
 762     case UNION_TYPE:
 763       if (val != 1 && !same_translation_unit_p (t1, t2))
 764         val = tagged_types_tu_compatible_p (t1, t2);
 765       break;
 766
 767     case VECTOR_TYPE:
 768       val = TYPE_VECTOR_SUBPARTS (t1) == TYPE_VECTOR_SUBPARTS (t2)
 769             && comptypes (TREE_TYPE (t1), TREE_TYPE (t2));
 770       break;
 771
 772     default:
 773       break;
 774     }
 775   return attrval == 2 && val == 1 ? 2 : val;
 776 }
 777
 778 /* Return 1 if TTL and TTR are pointers to types that are equivalent,
 779    ignoring their qualifiers.  REFLEXIVE is only used by ObjC - set it
 780    to 1 or 0 depending if the check of the pointer types is meant to
 781    be reflexive or not (typically, assignments are not reflexive,
 782    while comparisons are reflexive).
 783 */
 784
 785 static int
 786 comp_target_types (tree ttl, tree ttr, int reflexive)
 787 {
 788   int val;
 789   tree mvl, mvr;
 790
 791   /* Give objc_comptypes a crack at letting these types through.  */
 792   if ((val = objc_comptypes (ttl, ttr, reflexive)) >= 0)
 793     return val;
 794
 795   /* Do not lose qualifiers on element types of array types that are
 796      pointer targets by taking their TYPE_MAIN_VARIANT.  */
 797   mvl = TREE_TYPE (ttl);
 798   mvr = TREE_TYPE (ttr);
 799   if (TREE_CODE (mvl) != ARRAY_TYPE)
 800     mvl = TYPE_MAIN_VARIANT (mvl);
 801   if (TREE_CODE (mvr) != ARRAY_TYPE)
 802     mvr = TYPE_MAIN_VARIANT (mvr);
 803   val = comptypes (mvl, mvr);
 804
 805   if (val == 2 && pedantic)
 806     pedwarn ("types are not quite compatible");
 807   return val;
 808 }
 809 \f
 810 /* Subroutines of `comptypes'.  */
 811
 812 /* Determine whether two trees derive from the same translation unit.
 813    If the CONTEXT chain ends in a null, that tree's context is still
 814    being parsed, so if two trees have context chains ending in null,
 815    they're in the same translation unit.  */
 816 int
 817 same_translation_unit_p (tree t1, tree t2)
 818 {
 819   while (t1 && TREE_CODE (t1) != TRANSLATION_UNIT_DECL)
 820     switch (TREE_CODE_CLASS (TREE_CODE (t1)))
 821       {
 822       case tcc_declaration:
 823         t1 = DECL_CONTEXT (t1); break;
 824       case tcc_type:
 825         t1 = TYPE_CONTEXT (t1); break;
 826       case tcc_exceptional:
 827         t1 = BLOCK_SUPERCONTEXT (t1); break;  /* assume block */
 828       default: gcc_unreachable ();
 829       }
 830
 831   while (t2 && TREE_CODE (t2) != TRANSLATION_UNIT_DECL)
 832     switch (TREE_CODE_CLASS (TREE_CODE (t2)))
 833       {
 834       case tcc_declaration:
 835         t2 = DECL_CONTEXT (t2); break;
 836       case tcc_type:
 837         t2 = TYPE_CONTEXT (t2); break;
 838       case tcc_exceptional:
 839         t2 = BLOCK_SUPERCONTEXT (t2); break;  /* assume block */
 840       default: gcc_unreachable ();
 841       }
 842
 843   return t1 == t2;
 844 }
 845
 846 /* The C standard says that two structures in different translation
 847    units are compatible with each other only if the types of their
 848    fields are compatible (among other things).  So, consider two copies
 849    of this structure:  */
 850
 851 struct tagged_tu_seen {
 852   const struct tagged_tu_seen * next;
 853   tree t1;
 854   tree t2;
 855 };
 856
 857 /* Can they be compatible with each other?  We choose to break the
 858    recursion by allowing those types to be compatible.  */
 859
 860 static const struct tagged_tu_seen * tagged_tu_seen_base;
 861
 862 /* Return 1 if two 'struct', 'union', or 'enum' types T1 and T2 are
 863    compatible.  If the two types are not the same (which has been
 864    checked earlier), this can only happen when multiple translation
 865    units are being compiled.  See C99 6.2.7 paragraph 1 for the exact
 866    rules.  */
 867
 868 static int
 869 tagged_types_tu_compatible_p (tree t1, tree t2)
 870 {
 871   tree s1, s2;
 872   bool needs_warning = false;
 873
 874   /* We have to verify that the tags of the types are the same.  This
 875      is harder than it looks because this may be a typedef, so we have
 876      to go look at the original type.  It may even be a typedef of a
 877      typedef...
 878      In the case of compiler-created builtin structs the TYPE_DECL
 879      may be a dummy, with no DECL_ORIGINAL_TYPE.  Don't fault.  */
 880   while (TYPE_NAME (t1)
 881          && TREE_CODE (TYPE_NAME (t1)) == TYPE_DECL
 882          && DECL_ORIGINAL_TYPE (TYPE_NAME (t1)))
 883     t1 = DECL_ORIGINAL_TYPE (TYPE_NAME (t1));
 884
 885   while (TYPE_NAME (t2)
 886          && TREE_CODE (TYPE_NAME (t2)) == TYPE_DECL
 887          && DECL_ORIGINAL_TYPE (TYPE_NAME (t2)))
 888     t2 = DECL_ORIGINAL_TYPE (TYPE_NAME (t2));
 889
 890   /* C90 didn't have the requirement that the two tags be the same.  */
 891   if (flag_isoc99 && TYPE_NAME (t1) != TYPE_NAME (t2))
 892     return 0;
 893
 894   /* C90 didn't say what happened if one or both of the types were
 895      incomplete; we choose to follow C99 rules here, which is that they
 896      are compatible.  */
 897   if (TYPE_SIZE (t1) == NULL
 898       || TYPE_SIZE (t2) == NULL)
 899     return 1;
 900
 901   {
 902     const struct tagged_tu_seen * tts_i;
 903     for (tts_i = tagged_tu_seen_base; tts_i != NULL; tts_i = tts_i->next)
 904       if (tts_i->t1 == t1 && tts_i->t2 == t2)
 905         return 1;
 906   }
 907
 908   switch (TREE_CODE (t1))
 909     {
 910     case ENUMERAL_TYPE:
 911       {
 912
 913         /* Speed up the case where the type values are in the same order.  */
 914         tree tv1 = TYPE_VALUES (t1);
 915         tree tv2 = TYPE_VALUES (t2);
 916
 917         if (tv1 == tv2)
 918           return 1;
 919
 920         for (;tv1 && tv2; tv1 = TREE_CHAIN (tv1), tv2 = TREE_CHAIN (tv2))
 921           {
 922             if (TREE_PURPOSE (tv1) != TREE_PURPOSE (tv2))
 923               break;
 924             if (simple_cst_equal (TREE_VALUE (tv1), TREE_VALUE (tv2)) != 1)
 925               return 0;
 926           }
 927
 928         if (tv1 == NULL_TREE && tv2 == NULL_TREE)
 929           return 1;
 930         if (tv1 == NULL_TREE || tv2 == NULL_TREE)
 931           return 0;
 932
 933         if (list_length (TYPE_VALUES (t1)) != list_length (TYPE_VALUES (t2)))
 934           return 0;
 935
 936         for (s1 = TYPE_VALUES (t1); s1; s1 = TREE_CHAIN (s1))
 937           {
 938             s2 = purpose_member (TREE_PURPOSE (s1), TYPE_VALUES (t2));
 939             if (s2 == NULL
 940                 || simple_cst_equal (TREE_VALUE (s1), TREE_VALUE (s2)) != 1)
 941               return 0;
 942           }
 943         return 1;
 944       }
 945
 946     case UNION_TYPE:
 947       {
 948         if (list_length (TYPE_FIELDS (t1)) != list_length (TYPE_FIELDS (t2)))
 949           return 0;
 950
 951         for (s1 = TYPE_FIELDS (t1); s1; s1 = TREE_CHAIN (s1))
 952           {
 953             bool ok = false;
 954             struct tagged_tu_seen tts;
 955
 956             tts.next = tagged_tu_seen_base;
 957             tts.t1 = t1;
 958             tts.t2 = t2;
 959             tagged_tu_seen_base = &tts;
 960
 961             if (DECL_NAME (s1) != NULL)
 962               for (s2 = TYPE_FIELDS (t2); s2; s2 = TREE_CHAIN (s2))
 963                 if (DECL_NAME (s1) == DECL_NAME (s2))
 964                   {
 965                     int result;
 966                     result = comptypes (TREE_TYPE (s1), TREE_TYPE (s2));
 967                     if (result == 0)
 968                       break;
 969                     if (result == 2)
 970                       needs_warning = true;
 971
 972                     if (TREE_CODE (s1) == FIELD_DECL
 973                         && simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
 974                                              DECL_FIELD_BIT_OFFSET (s2)) != 1)
 975                       break;
 976
 977                     ok = true;
 978                     break;
 979                   }
 980             tagged_tu_seen_base = tts.next;
 981             if (!ok)
 982               return 0;
 983           }
 984         return needs_warning ? 2 : 1;
 985       }
 986
 987     case RECORD_TYPE:
 988       {
 989         struct tagged_tu_seen tts;
 990
 991         tts.next = tagged_tu_seen_base;
 992         tts.t1 = t1;
 993         tts.t2 = t2;
 994         tagged_tu_seen_base = &tts;
 995
 996         for (s1 = TYPE_FIELDS (t1), s2 = TYPE_FIELDS (t2);
 997              s1 && s2;
 998              s1 = TREE_CHAIN (s1), s2 = TREE_CHAIN (s2))
 999           {
1000             int result;
1001             if (TREE_CODE (s1) != TREE_CODE (s2)
1002                 || DECL_NAME (s1) != DECL_NAME (s2))
1003               break;
1004             result = comptypes (TREE_TYPE (s1), TREE_TYPE (s2));
1005             if (result == 0)
1006               break;
1007             if (result == 2)
1008               needs_warning = true;
1009
1010             if (TREE_CODE (s1) == FIELD_DECL
1011                 && simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
1012                                      DECL_FIELD_BIT_OFFSET (s2)) != 1)
1013               break;
1014           }
1015         tagged_tu_seen_base = tts.next;
1016         if (s1 && s2)
1017           return 0;
1018         return needs_warning ? 2 : 1;
1019       }
1020
1021     default:
1022       gcc_unreachable ();
1023     }
1024 }
1025
1026 /* Return 1 if two function types F1 and F2 are compatible.
1027    If either type specifies no argument types,
1028    the other must specify a fixed number of self-promoting arg types.
1029    Otherwise, if one type specifies only the number of arguments,
1030    the other must specify that number of self-promoting arg types.
1031    Otherwise, the argument types must match.  */
1032
1033 static int
1034 function_types_compatible_p (tree f1, tree f2)
1035 {
1036   tree args1, args2;
1037   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
1038   int val = 1;
1039   int val1;
1040   tree ret1, ret2;
1041
1042   ret1 = TREE_TYPE (f1);
1043   ret2 = TREE_TYPE (f2);
1044
1045   /* 'volatile' qualifiers on a function's return type used to mean
1046      the function is noreturn.  */
1047   if (TYPE_VOLATILE (ret1) != TYPE_VOLATILE (ret2))
1048     pedwarn ("function return types not compatible due to %<volatile%>");
1049   if (TYPE_VOLATILE (ret1))
1050     ret1 = build_qualified_type (TYPE_MAIN_VARIANT (ret1),
1051                                  TYPE_QUALS (ret1) & ~TYPE_QUAL_VOLATILE);
1052   if (TYPE_VOLATILE (ret2))
1053     ret2 = build_qualified_type (TYPE_MAIN_VARIANT (ret2),
1054                                  TYPE_QUALS (ret2) & ~TYPE_QUAL_VOLATILE);
1055   val = comptypes (ret1, ret2);
1056   if (val == 0)
1057     return 0;
1058
1059   args1 = TYPE_ARG_TYPES (f1);
1060   args2 = TYPE_ARG_TYPES (f2);
1061
1062   /* An unspecified parmlist matches any specified parmlist
1063      whose argument types don't need default promotions.  */
1064
1065   if (args1 == 0)
1066     {
1067       if (!self_promoting_args_p (args2))
1068         return 0;
1069       /* If one of these types comes from a non-prototype fn definition,
1070          compare that with the other type's arglist.
1071          If they don't match, ask for a warning (0, but no error).  */
1072       if (TYPE_ACTUAL_ARG_TYPES (f1)
1073           && 1 != type_lists_compatible_p (args2, TYPE_ACTUAL_ARG_TYPES (f1)))
1074         val = 2;
1075       return val;
1076     }
1077   if (args2 == 0)
1078     {
1079       if (!self_promoting_args_p (args1))
1080         return 0;
1081       if (TYPE_ACTUAL_ARG_TYPES (f2)
1082           && 1 != type_lists_compatible_p (args1, TYPE_ACTUAL_ARG_TYPES (f2)))
1083         val = 2;
1084       return val;
1085     }
1086
1087   /* Both types have argument lists: compare them and propagate results.  */
1088   val1 = type_lists_compatible_p (args1, args2);
1089   return val1 != 1 ? val1 : val;
1090 }
1091
1092 /* Check two lists of types for compatibility,
1093    returning 0 for incompatible, 1 for compatible,
1094    or 2 for compatible with warning.  */
1095
1096 static int
1097 type_lists_compatible_p (tree args1, tree args2)
1098 {
1099   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
1100   int val = 1;
1101   int newval = 0;
1102
1103   while (1)
1104     {
1105       tree a1, mv1, a2, mv2;
1106       if (args1 == 0 && args2 == 0)
1107         return val;
1108       /* If one list is shorter than the other,
1109          they fail to match.  */
1110       if (args1 == 0 || args2 == 0)
1111         return 0;
1112       mv1 = a1 = TREE_VALUE (args1);
1113       mv2 = a2 = TREE_VALUE (args2);
1114       if (mv1 && mv1 != error_mark_node && TREE_CODE (mv1) != ARRAY_TYPE)
1115         mv1 = TYPE_MAIN_VARIANT (mv1);
1116       if (mv2 && mv2 != error_mark_node && TREE_CODE (mv2) != ARRAY_TYPE)
1117         mv2 = TYPE_MAIN_VARIANT (mv2);
1118       /* A null pointer instead of a type
1119          means there is supposed to be an argument
1120          but nothing is specified about what type it has.
1121          So match anything that self-promotes.  */
1122       if (a1 == 0)
1123         {
1124           if (c_type_promotes_to (a2) != a2)
1125             return 0;
1126         }
1127       else if (a2 == 0)
1128         {
1129           if (c_type_promotes_to (a1) != a1)
1130             return 0;
1131         }
1132       /* If one of the lists has an error marker, ignore this arg.  */
1133       else if (TREE_CODE (a1) == ERROR_MARK
1134                || TREE_CODE (a2) == ERROR_MARK)
1135         ;
1136       else if (!(newval = comptypes (mv1, mv2)))
1137         {
1138           /* Allow  wait (union {union wait *u; int *i} *)
1139              and  wait (union wait *)  to be compatible.  */
1140           if (TREE_CODE (a1) == UNION_TYPE
1141               && (TYPE_NAME (a1) == 0
1142                   || TYPE_TRANSPARENT_UNION (a1))
1143               && TREE_CODE (TYPE_SIZE (a1)) == INTEGER_CST
1144               && tree_int_cst_equal (TYPE_SIZE (a1),
1145                                      TYPE_SIZE (a2)))
1146             {
1147               tree memb;
1148               for (memb = TYPE_FIELDS (a1);
1149                    memb; memb = TREE_CHAIN (memb))
1150                 {
1151                   tree mv3 = TREE_TYPE (memb);
1152                   if (mv3 && mv3 != error_mark_node
1153                       && TREE_CODE (mv3) != ARRAY_TYPE)
1154                     mv3 = TYPE_MAIN_VARIANT (mv3);
1155                   if (comptypes (mv3, mv2))
1156                     break;
1157                 }
1158               if (memb == 0)
1159                 return 0;
1160             }
1161           else if (TREE_CODE (a2) == UNION_TYPE
1162                    && (TYPE_NAME (a2) == 0
1163                        || TYPE_TRANSPARENT_UNION (a2))
1164                    && TREE_CODE (TYPE_SIZE (a2)) == INTEGER_CST
1165                    && tree_int_cst_equal (TYPE_SIZE (a2),
1166                                           TYPE_SIZE (a1)))
1167             {
1168               tree memb;
1169               for (memb = TYPE_FIELDS (a2);
1170                    memb; memb = TREE_CHAIN (memb))
1171                 {
1172                   tree mv3 = TREE_TYPE (memb);
1173                   if (mv3 && mv3 != error_mark_node
1174                       && TREE_CODE (mv3) != ARRAY_TYPE)
1175                     mv3 = TYPE_MAIN_VARIANT (mv3);
1176                   if (comptypes (mv3, mv1))
1177                     break;
1178                 }
1179               if (memb == 0)
1180                 return 0;
1181             }
1182           else
1183             return 0;
1184         }
1185
1186       /* comptypes said ok, but record if it said to warn.  */
1187       if (newval > val)
1188         val = newval;
1189
1190       args1 = TREE_CHAIN (args1);
1191       args2 = TREE_CHAIN (args2);
1192     }
1193 }
1194 \f
1195 /* Compute the size to increment a pointer by.  */
1196
1197 static tree
1198 c_size_in_bytes (tree type)
1199 {
1200   enum tree_code code = TREE_CODE (type);
1201
1202   if (code == FUNCTION_TYPE || code == VOID_TYPE || code == ERROR_MARK)
1203     return size_one_node;
1204
1205   if (!COMPLETE_OR_VOID_TYPE_P (type))
1206     {
1207       error ("arithmetic on pointer to an incomplete type");
1208       return size_one_node;
1209     }
1210
1211   /* Convert in case a char is more than one unit.  */
1212   return size_binop (CEIL_DIV_EXPR, TYPE_SIZE_UNIT (type),
1213                      size_int (TYPE_PRECISION (char_type_node)
1214                                / BITS_PER_UNIT));
1215 }
1216 \f
1217 /* Return either DECL or its known constant value (if it has one).  */
1218
1219 tree
1220 decl_constant_value (tree decl)
1221 {
1222   if (/* Don't change a variable array bound or initial value to a constant
1223          in a place where a variable is invalid.  Note that DECL_INITIAL
1224          isn't valid for a PARM_DECL.  */
1225       current_function_decl != 0
1226       && TREE_CODE (decl) != PARM_DECL
1227       && !TREE_THIS_VOLATILE (decl)
1228       && TREE_READONLY (decl)
1229       && DECL_INITIAL (decl) != 0
1230       && TREE_CODE (DECL_INITIAL (decl)) != ERROR_MARK
1231       /* This is invalid if initial value is not constant.
1232          If it has either a function call, a memory reference,
1233          or a variable, then re-evaluating it could give different results.  */
1234       && TREE_CONSTANT (DECL_INITIAL (decl))
1235       /* Check for cases where this is sub-optimal, even though valid.  */
1236       && TREE_CODE (DECL_INITIAL (decl)) != CONSTRUCTOR)
1237     return DECL_INITIAL (decl);
1238   return decl;
1239 }
1240
1241 /* Return either DECL or its known constant value (if it has one), but
1242    return DECL if pedantic or DECL has mode BLKmode.  This is for
1243    bug-compatibility with the old behavior of decl_constant_value
1244    (before GCC 3.0); every use of this function is a bug and it should
1245    be removed before GCC 3.1.  It is not appropriate to use pedantic
1246    in a way that affects optimization, and BLKmode is probably not the
1247    right test for avoiding misoptimizations either.  */
1248
1249 static tree
1250 decl_constant_value_for_broken_optimization (tree decl)
1251 {
1252   if (pedantic || DECL_MODE (decl) == BLKmode)
1253     return decl;
1254   else
1255     return decl_constant_value (decl);
1256 }
1257
1258
1259 /* Perform the default conversion of arrays and functions to pointers.
1260    Return the result of converting EXP.  For any other expression, just
1261    return EXP.  */
1262
1263 static tree
1264 default_function_array_conversion (tree exp)
1265 {
1266   tree orig_exp;
1267   tree type = TREE_TYPE (exp);
1268   enum tree_code code = TREE_CODE (type);
1269   int not_lvalue = 0;
1270
1271   /* Strip NON_LVALUE_EXPRs and no-op conversions, since we aren't using as
1272      an lvalue.
1273
1274      Do not use STRIP_NOPS here!  It will remove conversions from pointer
1275      to integer and cause infinite recursion.  */
1276   orig_exp = exp;
1277   while (TREE_CODE (exp) == NON_LVALUE_EXPR
1278          || (TREE_CODE (exp) == NOP_EXPR
1279              && TREE_TYPE (TREE_OPERAND (exp, 0)) == TREE_TYPE (exp)))
1280     {
1281       if (TREE_CODE (exp) == NON_LVALUE_EXPR)
1282         not_lvalue = 1;
1283       exp = TREE_OPERAND (exp, 0);
1284     }
1285
1286   if (TREE_NO_WARNING (orig_exp))
1287     TREE_NO_WARNING (exp) = 1;
1288
1289   if (code == FUNCTION_TYPE)
1290     {
1291       return build_unary_op (ADDR_EXPR, exp, 0);
1292     }
1293   if (code == ARRAY_TYPE)
1294     {
1295       tree adr;
1296       tree restype = TREE_TYPE (type);
1297       tree ptrtype;
1298       int constp = 0;
1299       int volatilep = 0;
1300       int lvalue_array_p;
1301
1302       if (REFERENCE_CLASS_P (exp) || DECL_P (exp))
1303         {
1304           constp = TREE_READONLY (exp);
1305           volatilep = TREE_THIS_VOLATILE (exp);
1306         }
1307
1308       if (TYPE_QUALS (type) || constp || volatilep)
1309         restype
1310           = c_build_qualified_type (restype,
1311                                     TYPE_QUALS (type)
1312                                     | (constp * TYPE_QUAL_CONST)
1313                                     | (volatilep * TYPE_QUAL_VOLATILE));
1314
1315       if (TREE_CODE (exp) == INDIRECT_REF)
1316         return convert (build_pointer_type (restype),
1317                         TREE_OPERAND (exp, 0));
1318
1319       if (TREE_CODE (exp) == COMPOUND_EXPR)
1320         {
1321           tree op1 = default_conversion (TREE_OPERAND (exp, 1));
1322           return build2 (COMPOUND_EXPR, TREE_TYPE (op1),
1323                          TREE_OPERAND (exp, 0), op1);
1324         }
1325
1326       lvalue_array_p = !not_lvalue && lvalue_p (exp);
1327       if (!flag_isoc99 && !lvalue_array_p)
1328         {
1329           /* Before C99, non-lvalue arrays do not decay to pointers.
1330              Normally, using such an array would be invalid; but it can
1331              be used correctly inside sizeof or as a statement expression.
1332              Thus, do not give an error here; an error will result later.  */
1333           return exp;
1334         }
1335
1336       ptrtype = build_pointer_type (restype);
1337
1338       if (TREE_CODE (exp) == VAR_DECL)
1339         {
1340           /* We are making an ADDR_EXPR of ptrtype.  This is a valid
1341              ADDR_EXPR because it's the best way of representing what
1342              happens in C when we take the address of an array and place
1343              it in a pointer to the element type.  */
1344           adr = build1 (ADDR_EXPR, ptrtype, exp);
1345           if (!c_mark_addressable (exp))
1346             return error_mark_node;
1347           TREE_SIDE_EFFECTS (adr) = 0;   /* Default would be, same as EXP.  */
1348           return adr;
1349         }
1350       /* This way is better for a COMPONENT_REF since it can
1351          simplify the offset for a component.  */
1352       adr = build_unary_op (ADDR_EXPR, exp, 1);
1353       return convert (ptrtype, adr);
1354     }
1355   return exp;
1356 }
1357
1358
1359 /* EXP is an expression of integer type.  Apply the integer promotions
1360    to it and return the promoted value.  */
1361
1362 tree
1363 perform_integral_promotions (tree exp)
1364 {
1365   tree type = TREE_TYPE (exp);
1366   enum tree_code code = TREE_CODE (type);
1367
1368   gcc_assert (INTEGRAL_TYPE_P (type));
1369
1370   /* Normally convert enums to int,
1371      but convert wide enums to something wider.  */
1372   if (code == ENUMERAL_TYPE)
1373     {
1374       type = c_common_type_for_size (MAX (TYPE_PRECISION (type),
1375                                           TYPE_PRECISION (integer_type_node)),
1376                                      ((TYPE_PRECISION (type)
1377                                        >= TYPE_PRECISION (integer_type_node))
1378                                       && TYPE_UNSIGNED (type)));
1379
1380       return convert (type, exp);
1381     }
1382
1383   /* ??? This should no longer be needed now bit-fields have their
1384      proper types.  */
1385   if (TREE_CODE (exp) == COMPONENT_REF
1386       && DECL_C_BIT_FIELD (TREE_OPERAND (exp, 1))
1387       /* If it's thinner than an int, promote it like a
1388          c_promoting_integer_type_p, otherwise leave it alone.  */
1389       && 0 > compare_tree_int (DECL_SIZE (TREE_OPERAND (exp, 1)),
1390                                TYPE_PRECISION (integer_type_node)))
1391     return convert (integer_type_node, exp);
1392
1393   if (c_promoting_integer_type_p (type))
1394     {
1395       /* Preserve unsignedness if not really getting any wider.  */
1396       if (TYPE_UNSIGNED (type)
1397           && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
1398         return convert (unsigned_type_node, exp);
1399
1400       return convert (integer_type_node, exp);
1401     }
1402
1403   return exp;
1404 }
1405
1406
1407 /* Perform default promotions for C data used in expressions.
1408    Arrays and functions are converted to pointers;
1409    enumeral types or short or char, to int.
1410    In addition, manifest constants symbols are replaced by their values.  */
1411
1412 tree
1413 default_conversion (tree exp)
1414 {
1415   tree orig_exp;
1416   tree type = TREE_TYPE (exp);
1417   enum tree_code code = TREE_CODE (type);
1418
1419   if (code == FUNCTION_TYPE || code == ARRAY_TYPE)
1420     return default_function_array_conversion (exp);
1421
1422   /* Constants can be used directly unless they're not loadable.  */
1423   if (TREE_CODE (exp) == CONST_DECL)
1424     exp = DECL_INITIAL (exp);
1425
1426   /* Replace a nonvolatile const static variable with its value unless
1427      it is an array, in which case we must be sure that taking the
1428      address of the array produces consistent results.  */
1429   else if (optimize && TREE_CODE (exp) == VAR_DECL && code != ARRAY_TYPE)
1430     {
1431       exp = decl_constant_value_for_broken_optimization (exp);
1432       type = TREE_TYPE (exp);
1433     }
1434
1435   /* Strip no-op conversions.  */
1436   orig_exp = exp;
1437   STRIP_TYPE_NOPS (exp);
1438
1439   if (TREE_NO_WARNING (orig_exp))
1440     TREE_NO_WARNING (exp) = 1;
1441
1442   if (INTEGRAL_TYPE_P (type))
1443     return perform_integral_promotions (exp);
1444
1445   if (code == VOID_TYPE)
1446     {
1447       error ("void value not ignored as it ought to be");
1448       return error_mark_node;
1449     }
1450   return exp;
1451 }
1452 \f
1453 /* Look up COMPONENT in a structure or union DECL.
1454
1455    If the component name is not found, returns NULL_TREE.  Otherwise,
1456    the return value is a TREE_LIST, with each TREE_VALUE a FIELD_DECL
1457    stepping down the chain to the component, which is in the last
1458    TREE_VALUE of the list.  Normally the list is of length one, but if
1459    the component is embedded within (nested) anonymous structures or
1460    unions, the list steps down the chain to the component.  */
1461
1462 static tree
1463 lookup_field (tree decl, tree component)
1464 {
1465   tree type = TREE_TYPE (decl);
1466   tree field;
1467
1468   /* If TYPE_LANG_SPECIFIC is set, then it is a sorted array of pointers
1469      to the field elements.  Use a binary search on this array to quickly
1470      find the element.  Otherwise, do a linear search.  TYPE_LANG_SPECIFIC
1471      will always be set for structures which have many elements.  */
1472
1473   if (TYPE_LANG_SPECIFIC (type) && TYPE_LANG_SPECIFIC (type)->s)
1474     {
1475       int bot, top, half;
1476       tree *field_array = &TYPE_LANG_SPECIFIC (type)->s->elts[0];
1477
1478       field = TYPE_FIELDS (type);
1479       bot = 0;
1480       top = TYPE_LANG_SPECIFIC (type)->s->len;
1481       while (top - bot > 1)
1482         {
1483           half = (top - bot + 1) >> 1;
1484           field = field_array[bot+half];
1485
1486           if (DECL_NAME (field) == NULL_TREE)
1487             {
1488               /* Step through all anon unions in linear fashion.  */
1489               while (DECL_NAME (field_array[bot]) == NULL_TREE)
1490                 {
1491                   field = field_array[bot++];
1492                   if (TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
1493                       || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
1494                     {
1495                       tree anon = lookup_field (field, component);
1496
1497                       if (anon)
1498                         return tree_cons (NULL_TREE, field, anon);
1499                     }
1500                 }
1501
1502               /* Entire record is only anon unions.  */
1503               if (bot > top)
1504                 return NULL_TREE;
1505
1506               /* Restart the binary search, with new lower bound.  */
1507               continue;
1508             }
1509
1510           if (DECL_NAME (field) == component)
1511             break;
1512           if (DECL_NAME (field) < component)
1513             bot += half;
1514           else
1515             top = bot + half;
1516         }
1517
1518       if (DECL_NAME (field_array[bot]) == component)
1519         field = field_array[bot];
1520       else if (DECL_NAME (field) != component)
1521         return NULL_TREE;
1522     }
1523   else
1524     {
1525       for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1526         {
1527           if (DECL_NAME (field) == NULL_TREE
1528               && (TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
1529                   || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE))
1530             {
1531               tree anon = lookup_field (field, component);
1532
1533               if (anon)
1534                 return tree_cons (NULL_TREE, field, anon);
1535             }
1536
1537           if (DECL_NAME (field) == component)
1538             break;
1539         }
1540
1541       if (field == NULL_TREE)
1542         return NULL_TREE;
1543     }
1544
1545   return tree_cons (NULL_TREE, field, NULL_TREE);
1546 }
1547
1548 /* Make an expression to refer to the COMPONENT field of
1549    structure or union value DATUM.  COMPONENT is an IDENTIFIER_NODE.  */
1550
1551 tree
1552 build_component_ref (tree datum, tree component)
1553 {
1554   tree type = TREE_TYPE (datum);
1555   enum tree_code code = TREE_CODE (type);
1556   tree field = NULL;
1557   tree ref;
1558
1559   if (!objc_is_public (datum, component))
1560     return error_mark_node;
1561
1562   /* See if there is a field or component with name COMPONENT.  */
1563
1564   if (code == RECORD_TYPE || code == UNION_TYPE)
1565     {
1566       if (!COMPLETE_TYPE_P (type))
1567         {
1568           c_incomplete_type_error (NULL_TREE, type);
1569           return error_mark_node;
1570         }
1571
1572       field = lookup_field (datum, component);
1573
1574       if (!field)
1575         {
1576           error ("%qT has no member named %qE", type, component);
1577           return error_mark_node;
1578         }
1579
1580       /* Chain the COMPONENT_REFs if necessary down to the FIELD.
1581          This might be better solved in future the way the C++ front
1582          end does it - by giving the anonymous entities each a
1583          separate name and type, and then have build_component_ref
1584          recursively call itself.  We can't do that here.  */
1585       do
1586         {
1587           tree subdatum = TREE_VALUE (field);
1588
1589           if (TREE_TYPE (subdatum) == error_mark_node)
1590             return error_mark_node;
1591
1592           ref = build3 (COMPONENT_REF, TREE_TYPE (subdatum), datum, subdatum,
1593                         NULL_TREE);
1594           if (TREE_READONLY (datum) || TREE_READONLY (subdatum))
1595             TREE_READONLY (ref) = 1;
1596           if (TREE_THIS_VOLATILE (datum) || TREE_THIS_VOLATILE (subdatum))
1597             TREE_THIS_VOLATILE (ref) = 1;
1598
1599           if (TREE_DEPRECATED (subdatum))
1600             warn_deprecated_use (subdatum);
1601
1602           datum = ref;
1603
1604           field = TREE_CHAIN (field);
1605         }
1606       while (field);
1607
1608       return ref;
1609     }
1610   else if (code != ERROR_MARK)
1611     error ("request for member %qE in something not a structure or union",
1612            component);
1613
1614   return error_mark_node;
1615 }
1616 \f
1617 /* Given an expression PTR for a pointer, return an expression
1618    for the value pointed to.
1619    ERRORSTRING is the name of the operator to appear in error messages.  */
1620
1621 tree
1622 build_indirect_ref (tree ptr, const char *errorstring)
1623 {
1624   tree pointer = default_conversion (ptr);
1625   tree type = TREE_TYPE (pointer);
1626
1627   if (TREE_CODE (type) == POINTER_TYPE)
1628     {
1629       if (TREE_CODE (pointer) == ADDR_EXPR
1630           && (TREE_TYPE (TREE_OPERAND (pointer, 0))
1631               == TREE_TYPE (type)))
1632         return TREE_OPERAND (pointer, 0);
1633       else
1634         {
1635           tree t = TREE_TYPE (type);
1636           tree mvt = t;
1637           tree ref;
1638
1639           if (TREE_CODE (mvt) != ARRAY_TYPE)
1640             mvt = TYPE_MAIN_VARIANT (mvt);
1641           ref = build1 (INDIRECT_REF, mvt, pointer);
1642
1643           if (!COMPLETE_OR_VOID_TYPE_P (t) && TREE_CODE (t) != ARRAY_TYPE)
1644             {
1645               error ("dereferencing pointer to incomplete type");
1646               return error_mark_node;
1647             }
1648           if (VOID_TYPE_P (t) && skip_evaluation == 0)
1649             warning (0, "dereferencing %<void *%> pointer");
1650
1651           /* We *must* set TREE_READONLY when dereferencing a pointer to const,
1652              so that we get the proper error message if the result is used
1653              to assign to.  Also, &* is supposed to be a no-op.
1654              And ANSI C seems to specify that the type of the result
1655              should be the const type.  */
1656           /* A de-reference of a pointer to const is not a const.  It is valid
1657              to change it via some other pointer.  */
1658           TREE_READONLY (ref) = TYPE_READONLY (t);
1659           TREE_SIDE_EFFECTS (ref)
1660             = TYPE_VOLATILE (t) || TREE_SIDE_EFFECTS (pointer);
1661           TREE_THIS_VOLATILE (ref) = TYPE_VOLATILE (t);
1662           return ref;
1663         }
1664     }
1665   else if (TREE_CODE (pointer) != ERROR_MARK)
1666     error ("invalid type argument of %qs", errorstring);
1667   return error_mark_node;
1668 }
1669
1670 /* This handles expressions of the form "a[i]", which denotes
1671    an array reference.
1672
1673    This is logically equivalent in C to *(a+i), but we may do it differently.
1674    If A is a variable or a member, we generate a primitive ARRAY_REF.
1675    This avoids forcing the array out of registers, and can work on
1676    arrays that are not lvalues (for example, members of structures returned
1677    by functions).  */
1678
1679 tree
1680 build_array_ref (tree array, tree index)
1681 {
1682   bool swapped = false;
1683   if (TREE_TYPE (array) == error_mark_node
1684       || TREE_TYPE (index) == error_mark_node)
1685     return error_mark_node;
1686
1687   if (TREE_CODE (TREE_TYPE (array)) != ARRAY_TYPE
1688       && TREE_CODE (TREE_TYPE (array)) != POINTER_TYPE)
1689     {
1690       tree temp;
1691       if (TREE_CODE (TREE_TYPE (index)) != ARRAY_TYPE
1692           && TREE_CODE (TREE_TYPE (index)) != POINTER_TYPE)
1693         {
1694           error ("subscripted value is neither array nor pointer");
1695           return error_mark_node;
1696         }
1697       temp = array;
1698       array = index;
1699       index = temp;
1700       swapped = true;
1701     }
1702
1703   if (!INTEGRAL_TYPE_P (TREE_TYPE (index)))
1704     {
1705       error ("array subscript is not an integer");
1706       return error_mark_node;
1707     }
1708
1709   if (TREE_CODE (TREE_TYPE (TREE_TYPE (array))) == FUNCTION_TYPE)
1710     {
1711       error ("subscripted value is pointer to function");
1712       return error_mark_node;
1713     }
1714
1715   /* Subscripting with type char is likely to lose on a machine where
1716      chars are signed.  So warn on any machine, but optionally.  Don't
1717      warn for unsigned char since that type is safe.  Don't warn for
1718      signed char because anyone who uses that must have done so
1719      deliberately.  ??? Existing practice has also been to warn only
1720      when the char index is syntactically the index, not for
1721      char[array].  */
1722   if (warn_char_subscripts && !swapped
1723       && TYPE_MAIN_VARIANT (TREE_TYPE (index)) == char_type_node)
1724     warning (0, "array subscript has type %<char%>");
1725
1726   /* Apply default promotions *after* noticing character types.  */
1727   index = default_conversion (index);
1728
1729   gcc_assert (TREE_CODE (TREE_TYPE (index)) == INTEGER_TYPE);
1730
1731   if (TREE_CODE (TREE_TYPE (array)) == ARRAY_TYPE)
1732     {
1733       tree rval, type;
1734
1735       /* An array that is indexed by a non-constant
1736          cannot be stored in a register; we must be able to do
1737          address arithmetic on its address.
1738          Likewise an array of elements of variable size.  */
1739       if (TREE_CODE (index) != INTEGER_CST
1740           || (COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (array)))
1741               && TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (array)))) != INTEGER_CST))
1742         {
1743           if (!c_mark_addressable (array))
1744             return error_mark_node;
1745         }
1746       /* An array that is indexed by a constant value which is not within
1747          the array bounds cannot be stored in a register either; because we
1748          would get a crash in store_bit_field/extract_bit_field when trying
1749          to access a non-existent part of the register.  */
1750       if (TREE_CODE (index) == INTEGER_CST
1751           && TYPE_DOMAIN (TREE_TYPE (array))
1752           && !int_fits_type_p (index, TYPE_DOMAIN (TREE_TYPE (array))))
1753         {
1754           if (!c_mark_addressable (array))
1755             return error_mark_node;
1756         }
1757
1758       if (pedantic)
1759         {
1760           tree foo = array;
1761           while (TREE_CODE (foo) == COMPONENT_REF)
1762             foo = TREE_OPERAND (foo, 0);
1763           if (TREE_CODE (foo) == VAR_DECL && C_DECL_REGISTER (foo))
1764             pedwarn ("ISO C forbids subscripting %<register%> array");
1765           else if (!flag_isoc99 && !lvalue_p (foo))
1766             pedwarn ("ISO C90 forbids subscripting non-lvalue array");
1767         }
1768
1769       type = TREE_TYPE (TREE_TYPE (array));
1770       if (TREE_CODE (type) != ARRAY_TYPE)
1771         type = TYPE_MAIN_VARIANT (type);
1772       rval = build4 (ARRAY_REF, type, array, index, NULL_TREE, NULL_TREE);
1773       /* Array ref is const/volatile if the array elements are
1774          or if the array is.  */
1775       TREE_READONLY (rval)
1776         |= (TYPE_READONLY (TREE_TYPE (TREE_TYPE (array)))
1777             | TREE_READONLY (array));
1778       TREE_SIDE_EFFECTS (rval)
1779         |= (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (array)))
1780             | TREE_SIDE_EFFECTS (array));
1781       TREE_THIS_VOLATILE (rval)
1782         |= (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (array)))
1783             /* This was added by rms on 16 Nov 91.
1784                It fixes  vol struct foo *a;  a->elts[1]
1785                in an inline function.
1786                Hope it doesn't break something else.  */
1787             | TREE_THIS_VOLATILE (array));
1788       return require_complete_type (fold (rval));
1789     }
1790   else
1791     {
1792       tree ar = default_conversion (array);
1793
1794       if (ar == error_mark_node)
1795         return ar;
1796
1797       gcc_assert (TREE_CODE (TREE_TYPE (ar)) == POINTER_TYPE);
1798       gcc_assert (TREE_CODE (TREE_TYPE (TREE_TYPE (ar))) != FUNCTION_TYPE);
1799
1800       return build_indirect_ref (build_binary_op (PLUS_EXPR, ar, index, 0),
1801                                  "array indexing");
1802     }
1803 }
1804 \f
1805 /* Build an external reference to identifier ID.  FUN indicates
1806    whether this will be used for a function call.  LOC is the source
1807    location of the identifier.  */
1808 tree
1809 build_external_ref (tree id, int fun, location_t loc)
1810 {
1811   tree ref;
1812   tree decl = lookup_name (id);
1813
1814   /* In Objective-C, an instance variable (ivar) may be preferred to
1815      whatever lookup_name() found.  */
1816   decl = objc_lookup_ivar (decl, id);
1817
1818   if (decl && decl != error_mark_node)
1819     ref = decl;
1820   else if (fun)
1821     /* Implicit function declaration.  */
1822     ref = implicitly_declare (id);
1823   else if (decl == error_mark_node)
1824     /* Don't complain about something that's already been
1825        complained about.  */
1826     return error_mark_node;
1827   else
1828     {
1829       undeclared_variable (id, loc);
1830       return error_mark_node;
1831     }
1832
1833   if (TREE_TYPE (ref) == error_mark_node)
1834     return error_mark_node;
1835
1836   if (TREE_DEPRECATED (ref))
1837     warn_deprecated_use (ref);
1838
1839   if (!skip_evaluation)
1840     assemble_external (ref);
1841   TREE_USED (ref) = 1;
1842
1843   if (TREE_CODE (ref) == FUNCTION_DECL && !in_alignof)
1844     {
1845       if (!in_sizeof && !in_typeof)
1846         C_DECL_USED (ref) = 1;
1847       else if (DECL_INITIAL (ref) == 0
1848                && DECL_EXTERNAL (ref)
1849                && !TREE_PUBLIC (ref))
1850         record_maybe_used_decl (ref);
1851     }
1852
1853   if (TREE_CODE (ref) == CONST_DECL)
1854     {
1855       ref = DECL_INITIAL (ref);
1856       TREE_CONSTANT (ref) = 1;
1857       TREE_INVARIANT (ref) = 1;
1858     }
1859   else if (current_function_decl != 0
1860            && !DECL_FILE_SCOPE_P (current_function_decl)
1861            && (TREE_CODE (ref) == VAR_DECL
1862                || TREE_CODE (ref) == PARM_DECL
1863                || TREE_CODE (ref) == FUNCTION_DECL))
1864     {
1865       tree context = decl_function_context (ref);
1866
1867       if (context != 0 && context != current_function_decl)
1868         DECL_NONLOCAL (ref) = 1;
1869     }
1870
1871   return ref;
1872 }
1873
1874 /* Record details of decls possibly used inside sizeof or typeof.  */
1875 struct maybe_used_decl
1876 {
1877   /* The decl.  */
1878   tree decl;
1879   /* The level seen at (in_sizeof + in_typeof).  */
1880   int level;
1881   /* The next one at this level or above, or NULL.  */
1882   struct maybe_used_decl *next;
1883 };
1884
1885 static struct maybe_used_decl *maybe_used_decls;
1886
1887 /* Record that DECL, an undefined static function reference seen
1888    inside sizeof or typeof, might be used if the operand of sizeof is
1889    a VLA type or the operand of typeof is a variably modified
1890    type.  */
1891
1892 static void
1893 record_maybe_used_decl (tree decl)
1894 {
1895   struct maybe_used_decl *t = XOBNEW (&parser_obstack, struct maybe_used_decl);
1896   t->decl = decl;
1897   t->level = in_sizeof + in_typeof;
1898   t->next = maybe_used_decls;
1899   maybe_used_decls = t;
1900 }
1901
1902 /* Pop the stack of decls possibly used inside sizeof or typeof.  If
1903    USED is false, just discard them.  If it is true, mark them used
1904    (if no longer inside sizeof or typeof) or move them to the next
1905    level up (if still inside sizeof or typeof).  */
1906
1907 void
1908 pop_maybe_used (bool used)
1909 {
1910   struct maybe_used_decl *p = maybe_used_decls;
1911   int cur_level = in_sizeof + in_typeof;
1912   while (p && p->level > cur_level)
1913     {
1914       if (used)
1915         {
1916           if (cur_level == 0)
1917             C_DECL_USED (p->decl) = 1;
1918           else
1919             p->level = cur_level;
1920         }
1921       p = p->next;
1922     }
1923   if (!used || cur_level == 0)
1924     maybe_used_decls = p;
1925 }
1926
1927 /* Return the result of sizeof applied to EXPR.  */
1928
1929 struct c_expr
1930 c_expr_sizeof_expr (struct c_expr expr)
1931 {
1932   struct c_expr ret;
1933   if (expr.value == error_mark_node)
1934     {
1935       ret.value = error_mark_node;
1936       ret.original_code = ERROR_MARK;
1937       pop_maybe_used (false);
1938     }
1939   else
1940     {
1941       ret.value = c_sizeof (TREE_TYPE (expr.value));
1942       ret.original_code = ERROR_MARK;
1943       pop_maybe_used (C_TYPE_VARIABLE_SIZE (TREE_TYPE (expr.value)));
1944     }
1945   return ret;
1946 }
1947
1948 /* Return the result of sizeof applied to T, a structure for the type
1949    name passed to sizeof (rather than the type itself).  */
1950
1951 struct c_expr
1952 c_expr_sizeof_type (struct c_type_name *t)
1953 {
1954   tree type;
1955   struct c_expr ret;
1956   type = groktypename (t);
1957   ret.value = c_sizeof (type);
1958   ret.original_code = ERROR_MARK;
1959   pop_maybe_used (C_TYPE_VARIABLE_SIZE (type));
1960   return ret;
1961 }
1962
1963 /* Build a function call to function FUNCTION with parameters PARAMS.
1964    PARAMS is a list--a chain of TREE_LIST nodes--in which the
1965    TREE_VALUE of each node is a parameter-expression.
1966    FUNCTION's data type may be a function type or a pointer-to-function.  */
1967
1968 tree
1969 build_function_call (tree function, tree params)
1970 {
1971   tree fntype, fundecl = 0;
1972   tree coerced_params;
1973   tree name = NULL_TREE, result;
1974   tree tem;
1975
1976   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
1977   STRIP_TYPE_NOPS (function);
1978
1979   /* Convert anything with function type to a pointer-to-function.  */
1980   if (TREE_CODE (function) == FUNCTION_DECL)
1981     {
1982       if (DECL_BUILT_IN_CLASS (function) == BUILT_IN_NORMAL)
1983         {
1984           tem = resolve_overloaded_builtin (function, params);
1985           if (tem)
1986             return tem;
1987         }
1988
1989       name = DECL_NAME (function);
1990
1991       /* Differs from default_conversion by not setting TREE_ADDRESSABLE
1992          (because calling an inline function does not mean the function
1993          needs to be separately compiled).  */
1994       fntype = build_type_variant (TREE_TYPE (function),
1995                                    TREE_READONLY (function),
1996                                    TREE_THIS_VOLATILE (function));
1997       fundecl = function;
1998       function = build1 (ADDR_EXPR, build_pointer_type (fntype), function);
1999     }
2000   else
2001     function = default_conversion (function);
2002
2003   fntype = TREE_TYPE (function);
2004
2005   if (TREE_CODE (fntype) == ERROR_MARK)
2006     return error_mark_node;
2007
2008   if (!(TREE_CODE (fntype) == POINTER_TYPE
2009         && TREE_CODE (TREE_TYPE (fntype)) == FUNCTION_TYPE))
2010     {
2011       error ("called object %qE is not a function", function);
2012       return error_mark_node;
2013     }
2014
2015   if (fundecl && TREE_THIS_VOLATILE (fundecl))
2016     current_function_returns_abnormally = 1;
2017
2018   /* fntype now gets the type of function pointed to.  */
2019   fntype = TREE_TYPE (fntype);
2020
2021   /* Check that the function is called through a compatible prototype.
2022      If it is not, replace the call by a trap, wrapped up in a compound
2023      expression if necessary.  This has the nice side-effect to prevent
2024      the tree-inliner from generating invalid assignment trees which may
2025      blow up in the RTL expander later.
2026
2027      ??? This doesn't work for Objective-C because objc_comptypes
2028      refuses to compare function prototypes, yet the compiler appears
2029      to build calls that are flagged as invalid by C's comptypes.  */
2030   if (!c_dialect_objc ()
2031       && TREE_CODE (function) == NOP_EXPR
2032       && TREE_CODE (tem = TREE_OPERAND (function, 0)) == ADDR_EXPR
2033       && TREE_CODE (tem = TREE_OPERAND (tem, 0)) == FUNCTION_DECL
2034       && !comptypes (fntype, TREE_TYPE (tem)))
2035     {
2036       tree return_type = TREE_TYPE (fntype);
2037       tree trap = build_function_call (built_in_decls[BUILT_IN_TRAP],
2038                                        NULL_TREE);
2039
2040       /* This situation leads to run-time undefined behavior.  We can't,
2041          therefore, simply error unless we can prove that all possible
2042          executions of the program must execute the code.  */
2043       warning (0, "function called through a non-compatible type");
2044
2045       /* We can, however, treat "undefined" any way we please.
2046          Call abort to encourage the user to fix the program.  */
2047       inform ("if this code is reached, the program will abort");
2048
2049       if (VOID_TYPE_P (return_type))
2050         return trap;
2051       else
2052         {
2053           tree rhs;
2054
2055           if (AGGREGATE_TYPE_P (return_type))
2056             rhs = build_compound_literal (return_type,
2057                                           build_constructor (return_type,
2058                                                              NULL_TREE));
2059           else
2060             rhs = fold (build1 (NOP_EXPR, return_type, integer_zero_node));
2061
2062           return build2 (COMPOUND_EXPR, return_type, trap, rhs);
2063         }
2064     }
2065
2066   /* Convert the parameters to the types declared in the
2067      function prototype, or apply default promotions.  */
2068
2069   coerced_params
2070     = convert_arguments (TYPE_ARG_TYPES (fntype), params, function, fundecl);
2071
2072   if (coerced_params == error_mark_node)
2073     return error_mark_node;
2074
2075   /* Check that the arguments to the function are valid.  */
2076
2077   check_function_arguments (TYPE_ATTRIBUTES (fntype), coerced_params);
2078
2079   result = build3 (CALL_EXPR, TREE_TYPE (fntype),
2080                    function, coerced_params, NULL_TREE);
2081   TREE_SIDE_EFFECTS (result) = 1;
2082
2083   if (require_constant_value)
2084     {
2085       result = fold_initializer (result);
2086
2087       if (TREE_CONSTANT (result)
2088           && (name == NULL_TREE
2089               || strncmp (IDENTIFIER_POINTER (name), "__builtin_", 10) != 0))
2090         pedwarn_init ("initializer element is not constant");
2091     }
2092   else
2093     result = fold (result);
2094
2095   if (VOID_TYPE_P (TREE_TYPE (result)))
2096     return result;
2097   return require_complete_type (result);
2098 }
2099 \f
2100 /* Convert the argument expressions in the list VALUES
2101    to the types in the list TYPELIST.  The result is a list of converted
2102    argument expressions, unless there are too few arguments in which
2103    case it is error_mark_node.
2104
2105    If TYPELIST is exhausted, or when an element has NULL as its type,
2106    perform the default conversions.
2107
2108    PARMLIST is the chain of parm decls for the function being called.
2109    It may be 0, if that info is not available.
2110    It is used only for generating error messages.
2111
2112    FUNCTION is a tree for the called function.  It is used only for
2113    error messages, where it is formatted with %qE.
2114
2115    This is also where warnings about wrong number of args are generated.
2116
2117    Both VALUES and the returned value are chains of TREE_LIST nodes
2118    with the elements of the list in the TREE_VALUE slots of those nodes.  */
2119
2120 static tree
2121 convert_arguments (tree typelist, tree values, tree function, tree fundecl)
2122 {
2123   tree typetail, valtail;
2124   tree result = NULL;
2125   int parmnum;
2126   tree selector;
2127
2128   /* Change pointer to function to the function itself for
2129      diagnostics.  */
2130   if (TREE_CODE (function) == ADDR_EXPR
2131       && TREE_CODE (TREE_OPERAND (function, 0)) == FUNCTION_DECL)
2132     function = TREE_OPERAND (function, 0);
2133
2134   /* Handle an ObjC selector specially for diagnostics.  */
2135   selector = objc_message_selector ();
2136
2137   /* Scan the given expressions and types, producing individual
2138      converted arguments and pushing them on RESULT in reverse order.  */
2139
2140   for (valtail = values, typetail = typelist, parmnum = 0;
2141        valtail;
2142        valtail = TREE_CHAIN (valtail), parmnum++)
2143     {
2144       tree type = typetail ? TREE_VALUE (typetail) : 0;
2145       tree val = TREE_VALUE (valtail);
2146       tree rname = function;
2147       int argnum = parmnum + 1;
2148       const char *invalid_func_diag;
2149
2150       if (type == void_type_node)
2151         {
2152           error ("too many arguments to function %qE", function);
2153           break;
2154         }
2155
2156       if (selector && argnum > 2)
2157         {
2158           rname = selector;
2159           argnum -= 2;
2160         }
2161
2162       STRIP_TYPE_NOPS (val);
2163
2164       val = default_function_array_conversion (val);
2165
2166       val = require_complete_type (val);
2167
2168       if (type != 0)
2169         {
2170           /* Formal parm type is specified by a function prototype.  */
2171           tree parmval;
2172
2173           if (type == error_mark_node || !COMPLETE_TYPE_P (type))
2174             {
2175               error ("type of formal parameter %d is incomplete", parmnum + 1);
2176               parmval = val;
2177             }
2178           else
2179             {
2180               /* Optionally warn about conversions that
2181                  differ from the default conversions.  */
2182               if (warn_conversion || warn_traditional)
2183                 {
2184                   unsigned int formal_prec = TYPE_PRECISION (type);
2185
2186                   if (INTEGRAL_TYPE_P (type)
2187                       && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
2188                     warning (0, "passing argument %d of %qE as integer "
2189                              "rather than floating due to prototype",
2190                              argnum, rname);
2191                   if (INTEGRAL_TYPE_P (type)
2192                       && TREE_CODE (TREE_TYPE (val)) == COMPLEX_TYPE)
2193                     warning (0, "passing argument %d of %qE as integer "
2194                              "rather than complex due to prototype",
2195                              argnum, rname);
2196                   else if (TREE_CODE (type) == COMPLEX_TYPE
2197                            && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
2198                     warning (0, "passing argument %d of %qE as complex "
2199                              "rather than floating due to prototype",
2200                              argnum, rname);
2201                   else if (TREE_CODE (type) == REAL_TYPE
2202                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2203                     warning (0, "passing argument %d of %qE as floating "
2204                              "rather than integer due to prototype",
2205                              argnum, rname);
2206                   else if (TREE_CODE (type) == COMPLEX_TYPE
2207                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2208                     warning (0, "passing argument %d of %qE as complex "
2209                              "rather than integer due to prototype",
2210                              argnum, rname);
2211                   else if (TREE_CODE (type) == REAL_TYPE
2212                            && TREE_CODE (TREE_TYPE (val)) == COMPLEX_TYPE)
2213                     warning (0, "passing argument %d of %qE as floating "
2214                              "rather than complex due to prototype",
2215                              argnum, rname);
2216                   /* ??? At some point, messages should be written about
2217                      conversions between complex types, but that's too messy
2218                      to do now.  */
2219                   else if (TREE_CODE (type) == REAL_TYPE
2220                            && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
2221                     {
2222                       /* Warn if any argument is passed as `float',
2223                          since without a prototype it would be `double'.  */
2224                       if (formal_prec == TYPE_PRECISION (float_type_node))
2225                         warning (0, "passing argument %d of %qE as %<float%> "
2226                                  "rather than %<double%> due to prototype",
2227                                  argnum, rname);
2228                     }
2229                   /* Detect integer changing in width or signedness.
2230                      These warnings are only activated with
2231                      -Wconversion, not with -Wtraditional.  */
2232                   else if (warn_conversion && INTEGRAL_TYPE_P (type)
2233                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2234                     {
2235                       tree would_have_been = default_conversion (val);
2236                       tree type1 = TREE_TYPE (would_have_been);
2237
2238                       if (TREE_CODE (type) == ENUMERAL_TYPE
2239                           && (TYPE_MAIN_VARIANT (type)
2240                               == TYPE_MAIN_VARIANT (TREE_TYPE (val))))
2241                         /* No warning if function asks for enum
2242                            and the actual arg is that enum type.  */
2243                         ;
2244                       else if (formal_prec != TYPE_PRECISION (type1))
2245                         warning (0, "passing argument %d of %qE with different "
2246                                  "width due to prototype", argnum, rname);
2247                       else if (TYPE_UNSIGNED (type) == TYPE_UNSIGNED (type1))
2248                         ;
2249                       /* Don't complain if the formal parameter type
2250                          is an enum, because we can't tell now whether
2251                          the value was an enum--even the same enum.  */
2252                       else if (TREE_CODE (type) == ENUMERAL_TYPE)
2253                         ;
2254                       else if (TREE_CODE (val) == INTEGER_CST
2255                                && int_fits_type_p (val, type))
2256                         /* Change in signedness doesn't matter
2257                            if a constant value is unaffected.  */
2258                         ;
2259                       /* If the value is extended from a narrower
2260                          unsigned type, it doesn't matter whether we
2261                          pass it as signed or unsigned; the value
2262                          certainly is the same either way.  */
2263                       else if (TYPE_PRECISION (TREE_TYPE (val)) < TYPE_PRECISION (type)
2264                                && TYPE_UNSIGNED (TREE_TYPE (val)))
2265                         ;
2266                       else if (TYPE_UNSIGNED (type))
2267                         warning (0, "passing argument %d of %qE as unsigned "
2268                                  "due to prototype", argnum, rname);
2269                       else
2270                         warning (0, "passing argument %d of %qE as signed "
2271                                  "due to prototype", argnum, rname);
2272                     }
2273                 }
2274
2275               parmval = convert_for_assignment (type, val, ic_argpass,
2276                                                 fundecl, function,
2277                                                 parmnum + 1);
2278
2279               if (targetm.calls.promote_prototypes (fundecl ? TREE_TYPE (fundecl) : 0)
2280                   && INTEGRAL_TYPE_P (type)
2281                   && (TYPE_PRECISION (type) < TYPE_PRECISION (integer_type_node)))
2282                 parmval = default_conversion (parmval);
2283             }
2284           result = tree_cons (NULL_TREE, parmval, result);
2285         }
2286       else if (TREE_CODE (TREE_TYPE (val)) == REAL_TYPE
2287                && (TYPE_PRECISION (TREE_TYPE (val))
2288                    < TYPE_PRECISION (double_type_node)))
2289         /* Convert `float' to `double'.  */
2290         result = tree_cons (NULL_TREE, convert (double_type_node, val), result);
2291       else if ((invalid_func_diag =
2292                 targetm.calls.invalid_arg_for_unprototyped_fn (typelist, fundecl, val)))
2293         {
2294           error (invalid_func_diag);
2295           return error_mark_node;
2296         }
2297       else
2298         /* Convert `short' and `char' to full-size `int'.  */
2299         result = tree_cons (NULL_TREE, default_conversion (val), result);
2300
2301       if (typetail)
2302         typetail = TREE_CHAIN (typetail);
2303     }
2304
2305   if (typetail != 0 && TREE_VALUE (typetail) != void_type_node)
2306     {
2307       error ("too few arguments to function %qE", function);
2308       return error_mark_node;
2309     }
2310
2311   return nreverse (result);
2312 }
2313 \f
2314 /* This is the entry point used by the parser
2315    for binary operators in the input.
2316    In addition to constructing the expression,
2317    we check for operands that were written with other binary operators
2318    in a way that is likely to confuse the user.  */
2319
2320 struct c_expr
2321 parser_build_binary_op (enum tree_code code, struct c_expr arg1,
2322                         struct c_expr arg2)
2323 {
2324   struct c_expr result;
2325
2326   enum tree_code code1 = arg1.original_code;
2327   enum tree_code code2 = arg2.original_code;
2328
2329   result.value = build_binary_op (code, arg1.value, arg2.value, 1);
2330   result.original_code = code;
2331
2332   if (TREE_CODE (result.value) == ERROR_MARK)
2333     return result;
2334
2335   /* Check for cases such as x+y<<z which users are likely
2336      to misinterpret.  */
2337   if (warn_parentheses)
2338     {
2339       if (code == LSHIFT_EXPR || code == RSHIFT_EXPR)
2340         {
2341           if (code1 == PLUS_EXPR || code1 == MINUS_EXPR
2342               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2343             warning (0, "suggest parentheses around + or - inside shift");
2344         }
2345
2346       if (code == TRUTH_ORIF_EXPR)
2347         {
2348           if (code1 == TRUTH_ANDIF_EXPR
2349               || code2 == TRUTH_ANDIF_EXPR)
2350             warning (0, "suggest parentheses around && within ||");
2351         }
2352
2353       if (code == BIT_IOR_EXPR)
2354         {
2355           if (code1 == BIT_AND_EXPR || code1 == BIT_XOR_EXPR
2356               || code1 == PLUS_EXPR || code1 == MINUS_EXPR
2357               || code2 == BIT_AND_EXPR || code2 == BIT_XOR_EXPR
2358               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2359             warning (0, "suggest parentheses around arithmetic in operand of |");
2360           /* Check cases like x|y==z */
2361           if (TREE_CODE_CLASS (code1) == tcc_comparison
2362               || TREE_CODE_CLASS (code2) == tcc_comparison)
2363             warning (0, "suggest parentheses around comparison in operand of |");
2364         }
2365
2366       if (code == BIT_XOR_EXPR)
2367         {
2368           if (code1 == BIT_AND_EXPR
2369               || code1 == PLUS_EXPR || code1 == MINUS_EXPR
2370               || code2 == BIT_AND_EXPR
2371               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2372             warning (0, "suggest parentheses around arithmetic in operand of ^");
2373           /* Check cases like x^y==z */
2374           if (TREE_CODE_CLASS (code1) == tcc_comparison
2375               || TREE_CODE_CLASS (code2) == tcc_comparison)
2376             warning (0, "suggest parentheses around comparison in operand of ^");
2377         }
2378
2379       if (code == BIT_AND_EXPR)
2380         {
2381           if (code1 == PLUS_EXPR || code1 == MINUS_EXPR
2382               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2383             warning (0, "suggest parentheses around + or - in operand of &");
2384           /* Check cases like x&y==z */
2385           if (TREE_CODE_CLASS (code1) == tcc_comparison
2386               || TREE_CODE_CLASS (code2) == tcc_comparison)
2387             warning (0, "suggest parentheses around comparison in operand of &");
2388         }
2389       /* Similarly, check for cases like 1<=i<=10 that are probably errors.  */
2390       if (TREE_CODE_CLASS (code) == tcc_comparison
2391           && (TREE_CODE_CLASS (code1) == tcc_comparison
2392               || TREE_CODE_CLASS (code2) == tcc_comparison))
2393         warning (0, "comparisons like X<=Y<=Z do not have their mathematical meaning");
2394
2395     }
2396
2397   unsigned_conversion_warning (result.value, arg1.value);
2398   unsigned_conversion_warning (result.value, arg2.value);
2399   overflow_warning (result.value);
2400
2401   return result;
2402 }
2403 \f
2404 /* Return a tree for the difference of pointers OP0 and OP1.
2405    The resulting tree has type int.  */
2406
2407 static tree
2408 pointer_diff (tree op0, tree op1)
2409 {
2410   tree restype = ptrdiff_type_node;
2411
2412   tree target_type = TREE_TYPE (TREE_TYPE (op0));
2413   tree con0, con1, lit0, lit1;
2414   tree orig_op1 = op1;
2415
2416   if (pedantic || warn_pointer_arith)
2417     {
2418       if (TREE_CODE (target_type) == VOID_TYPE)
2419         pedwarn ("pointer of type %<void *%> used in subtraction");
2420       if (TREE_CODE (target_type) == FUNCTION_TYPE)
2421         pedwarn ("pointer to a function used in subtraction");
2422     }
2423
2424   /* If the conversion to ptrdiff_type does anything like widening or
2425      converting a partial to an integral mode, we get a convert_expression
2426      that is in the way to do any simplifications.
2427      (fold-const.c doesn't know that the extra bits won't be needed.
2428      split_tree uses STRIP_SIGN_NOPS, which leaves conversions to a
2429      different mode in place.)
2430      So first try to find a common term here 'by hand'; we want to cover
2431      at least the cases that occur in legal static initializers.  */
2432   con0 = TREE_CODE (op0) == NOP_EXPR ? TREE_OPERAND (op0, 0) : op0;
2433   con1 = TREE_CODE (op1) == NOP_EXPR ? TREE_OPERAND (op1, 0) : op1;
2434
2435   if (TREE_CODE (con0) == PLUS_EXPR)
2436     {
2437       lit0 = TREE_OPERAND (con0, 1);
2438       con0 = TREE_OPERAND (con0, 0);
2439     }
2440   else
2441     lit0 = integer_zero_node;
2442
2443   if (TREE_CODE (con1) == PLUS_EXPR)
2444     {
2445       lit1 = TREE_OPERAND (con1, 1);
2446       con1 = TREE_OPERAND (con1, 0);
2447     }
2448   else
2449     lit1 = integer_zero_node;
2450
2451   if (operand_equal_p (con0, con1, 0))
2452     {
2453       op0 = lit0;
2454       op1 = lit1;
2455     }
2456
2457
2458   /* First do the subtraction as integers;
2459      then drop through to build the divide operator.
2460      Do not do default conversions on the minus operator
2461      in case restype is a short type.  */
2462
2463   op0 = build_binary_op (MINUS_EXPR, convert (restype, op0),
2464                          convert (restype, op1), 0);
2465   /* This generates an error if op1 is pointer to incomplete type.  */
2466   if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (TREE_TYPE (orig_op1))))
2467     error ("arithmetic on pointer to an incomplete type");
2468
2469   /* This generates an error if op0 is pointer to incomplete type.  */
2470   op1 = c_size_in_bytes (target_type);
2471
2472   /* Divide by the size, in easiest possible way.  */
2473   return fold (build2 (EXACT_DIV_EXPR, restype, op0, convert (restype, op1)));
2474 }
2475 \f
2476 /* Construct and perhaps optimize a tree representation
2477    for a unary operation.  CODE, a tree_code, specifies the operation
2478    and XARG is the operand.
2479    For any CODE other than ADDR_EXPR, FLAG nonzero suppresses
2480    the default promotions (such as from short to int).
2481    For ADDR_EXPR, the default promotions are not applied; FLAG nonzero
2482    allows non-lvalues; this is only used to handle conversion of non-lvalue
2483    arrays to pointers in C99.  */
2484
2485 tree
2486 build_unary_op (enum tree_code code, tree xarg, int flag)
2487 {
2488   /* No default_conversion here.  It causes trouble for ADDR_EXPR.  */
2489   tree arg = xarg;
2490   tree argtype = 0;
2491   enum tree_code typecode = TREE_CODE (TREE_TYPE (arg));
2492   tree val;
2493   int noconvert = flag;
2494
2495   if (typecode == ERROR_MARK)
2496     return error_mark_node;
2497   if (typecode == ENUMERAL_TYPE || typecode == BOOLEAN_TYPE)
2498     typecode = INTEGER_TYPE;
2499
2500   switch (code)
2501     {
2502     case CONVERT_EXPR:
2503       /* This is used for unary plus, because a CONVERT_EXPR
2504          is enough to prevent anybody from looking inside for
2505          associativity, but won't generate any code.  */
2506       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2507             || typecode == COMPLEX_TYPE
2508             || typecode == VECTOR_TYPE))
2509         {
2510           error ("wrong type argument to unary plus");
2511           return error_mark_node;
2512         }
2513       else if (!noconvert)
2514         arg = default_conversion (arg);
2515       arg = non_lvalue (arg);
2516       break;
2517
2518     case NEGATE_EXPR:
2519       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2520             || typecode == COMPLEX_TYPE
2521             || typecode == VECTOR_TYPE))
2522         {
2523           error ("wrong type argument to unary minus");
2524           return error_mark_node;
2525         }
2526       else if (!noconvert)
2527         arg = default_conversion (arg);
2528       break;
2529
2530     case BIT_NOT_EXPR:
2531       if (typecode == INTEGER_TYPE || typecode == VECTOR_TYPE)
2532         {
2533           if (!noconvert)
2534             arg = default_conversion (arg);
2535         }
2536       else if (typecode == COMPLEX_TYPE)
2537         {
2538           code = CONJ_EXPR;
2539           if (pedantic)
2540             pedwarn ("ISO C does not support %<~%> for complex conjugation");
2541           if (!noconvert)
2542             arg = default_conversion (arg);
2543         }
2544       else
2545         {
2546           error ("wrong type argument to bit-complement");
2547           return error_mark_node;
2548         }
2549       break;
2550
2551     case ABS_EXPR:
2552       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE))
2553         {
2554           error ("wrong type argument to abs");
2555           return error_mark_node;
2556         }
2557       else if (!noconvert)
2558         arg = default_conversion (arg);
2559       break;
2560
2561     case CONJ_EXPR:
2562       /* Conjugating a real value is a no-op, but allow it anyway.  */
2563       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2564             || typecode == COMPLEX_TYPE))
2565         {
2566           error ("wrong type argument to conjugation");
2567           return error_mark_node;
2568         }
2569       else if (!noconvert)
2570         arg = default_conversion (arg);
2571       break;
2572
2573     case TRUTH_NOT_EXPR:
2574       /* ??? Why do most validation here but that for non-lvalue arrays
2575          in c_objc_common_truthvalue_conversion?  */
2576       if (typecode != INTEGER_TYPE
2577           && typecode != REAL_TYPE && typecode != POINTER_TYPE
2578           && typecode != COMPLEX_TYPE
2579           /* These will convert to a pointer.  */
2580           && typecode != ARRAY_TYPE && typecode != FUNCTION_TYPE)
2581         {
2582           error ("wrong type argument to unary exclamation mark");
2583           return error_mark_node;
2584         }
2585       arg = c_objc_common_truthvalue_conversion (arg);
2586       return invert_truthvalue (arg);
2587
2588     case NOP_EXPR:
2589       break;
2590
2591     case REALPART_EXPR:
2592       if (TREE_CODE (arg) == COMPLEX_CST)
2593         return TREE_REALPART (arg);
2594       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
2595         return fold (build1 (REALPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg));
2596       else
2597         return arg;
2598
2599     case IMAGPART_EXPR:
2600       if (TREE_CODE (arg) == COMPLEX_CST)
2601         return TREE_IMAGPART (arg);
2602       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
2603         return fold (build1 (IMAGPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg));
2604       else
2605         return convert (TREE_TYPE (arg), integer_zero_node);
2606
2607     case PREINCREMENT_EXPR:
2608     case POSTINCREMENT_EXPR:
2609     case PREDECREMENT_EXPR:
2610     case POSTDECREMENT_EXPR:
2611
2612       /* Increment or decrement the real part of the value,
2613          and don't change the imaginary part.  */
2614       if (typecode == COMPLEX_TYPE)
2615         {
2616           tree real, imag;
2617
2618           if (pedantic)
2619             pedwarn ("ISO C does not support %<++%> and %<--%>"
2620                      " on complex types");
2621
2622           arg = stabilize_reference (arg);
2623           real = build_unary_op (REALPART_EXPR, arg, 1);
2624           imag = build_unary_op (IMAGPART_EXPR, arg, 1);
2625           return build2 (COMPLEX_EXPR, TREE_TYPE (arg),
2626                          build_unary_op (code, real, 1), imag);
2627         }
2628
2629       /* Report invalid types.  */
2630
2631       if (typecode != POINTER_TYPE
2632           && typecode != INTEGER_TYPE && typecode != REAL_TYPE)
2633         {
2634           if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
2635             error ("wrong type argument to increment");
2636           else
2637             error ("wrong type argument to decrement");
2638
2639           return error_mark_node;
2640         }
2641
2642       {
2643         tree inc;
2644         tree result_type = TREE_TYPE (arg);
2645
2646         arg = get_unwidened (arg, 0);
2647         argtype = TREE_TYPE (arg);
2648
2649         /* Compute the increment.  */
2650
2651         if (typecode == POINTER_TYPE)
2652           {
2653             /* If pointer target is an undefined struct,
2654                we just cannot know how to do the arithmetic.  */
2655             if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (result_type)))
2656               {
2657                 if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
2658                   error ("increment of pointer to unknown structure");
2659                 else
2660                   error ("decrement of pointer to unknown structure");
2661               }
2662             else if ((pedantic || warn_pointer_arith)
2663                      && (TREE_CODE (TREE_TYPE (result_type)) == FUNCTION_TYPE
2664                          || TREE_CODE (TREE_TYPE (result_type)) == VOID_TYPE))
2665               {
2666                 if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
2667                   pedwarn ("wrong type argument to increment");
2668                 else
2669                   pedwarn ("wrong type argument to decrement");
2670               }
2671
2672             inc = c_size_in_bytes (TREE_TYPE (result_type));
2673           }
2674         else
2675           inc = integer_one_node;
2676
2677         inc = convert (argtype, inc);
2678
2679         /* Complain about anything else that is not a true lvalue.  */
2680         if (!lvalue_or_else (arg, ((code == PREINCREMENT_EXPR
2681                                     || code == POSTINCREMENT_EXPR)
2682                                    ? lv_increment
2683                                    : lv_decrement)))
2684           return error_mark_node;
2685
2686         /* Report a read-only lvalue.  */
2687         if (TREE_READONLY (arg))
2688           readonly_error (arg,
2689                           ((code == PREINCREMENT_EXPR
2690                             || code == POSTINCREMENT_EXPR)
2691                            ? lv_increment : lv_decrement));
2692
2693         if (TREE_CODE (TREE_TYPE (arg)) == BOOLEAN_TYPE)
2694           val = boolean_increment (code, arg);
2695         else
2696           val = build2 (code, TREE_TYPE (arg), arg, inc);
2697         TREE_SIDE_EFFECTS (val) = 1;
2698         val = convert (result_type, val);
2699         if (TREE_CODE (val) != code)
2700           TREE_NO_WARNING (val) = 1;
2701         return val;
2702       }
2703
2704     case ADDR_EXPR:
2705       /* Note that this operation never does default_conversion.  */
2706
2707       /* Let &* cancel out to simplify resulting code.  */
2708       if (TREE_CODE (arg) == INDIRECT_REF)
2709         {
2710           /* Don't let this be an lvalue.  */
2711           if (lvalue_p (TREE_OPERAND (arg, 0)))
2712             return non_lvalue (TREE_OPERAND (arg, 0));
2713           return TREE_OPERAND (arg, 0);
2714         }
2715
2716       /* For &x[y], return x+y */
2717       if (TREE_CODE (arg) == ARRAY_REF)
2718         {
2719           if (!c_mark_addressable (TREE_OPERAND (arg, 0)))
2720             return error_mark_node;
2721           return build_binary_op (PLUS_EXPR, TREE_OPERAND (arg, 0),
2722                                   TREE_OPERAND (arg, 1), 1);
2723         }
2724
2725       /* Anything not already handled and not a true memory reference
2726          or a non-lvalue array is an error.  */
2727       else if (typecode != FUNCTION_TYPE && !flag
2728                && !lvalue_or_else (arg, lv_addressof))
2729         return error_mark_node;
2730
2731       /* Ordinary case; arg is a COMPONENT_REF or a decl.  */
2732       argtype = TREE_TYPE (arg);
2733
2734       /* If the lvalue is const or volatile, merge that into the type
2735          to which the address will point.  Note that you can't get a
2736          restricted pointer by taking the address of something, so we
2737          only have to deal with `const' and `volatile' here.  */
2738       if ((DECL_P (arg) || REFERENCE_CLASS_P (arg))
2739           && (TREE_READONLY (arg) || TREE_THIS_VOLATILE (arg)))
2740           argtype = c_build_type_variant (argtype,
2741                                           TREE_READONLY (arg),
2742                                           TREE_THIS_VOLATILE (arg));
2743
2744       if (!c_mark_addressable (arg))
2745         return error_mark_node;
2746
2747       gcc_assert (TREE_CODE (arg) != COMPONENT_REF
2748                   || !DECL_C_BIT_FIELD (TREE_OPERAND (arg, 1)));
2749
2750       argtype = build_pointer_type (argtype);
2751
2752       /* ??? Cope with user tricks that amount to offsetof.  Delete this
2753          when we have proper support for integer constant expressions.  */
2754       val = get_base_address (arg);
2755       if (val && TREE_CODE (val) == INDIRECT_REF
2756           && integer_zerop (TREE_OPERAND (val, 0)))
2757         return fold_convert (argtype, fold_offsetof (arg));
2758
2759       val = build1 (ADDR_EXPR, argtype, arg);
2760
2761       if (TREE_CODE (arg) == COMPOUND_LITERAL_EXPR)
2762         TREE_INVARIANT (val) = TREE_CONSTANT (val) = 1;
2763
2764       return val;
2765
2766     default:
2767       break;
2768     }
2769
2770   if (argtype == 0)
2771     argtype = TREE_TYPE (arg);
2772   val = build1 (code, argtype, arg);
2773   return require_constant_value ? fold_initializer (val) : fold (val);
2774 }
2775
2776 /* Return nonzero if REF is an lvalue valid for this language.
2777    Lvalues can be assigned, unless their type has TYPE_READONLY.
2778    Lvalues can have their address taken, unless they have C_DECL_REGISTER.  */
2779
2780 static int
2781 lvalue_p (tree ref)
2782 {
2783   enum tree_code code = TREE_CODE (ref);
2784
2785   switch (code)
2786     {
2787     case REALPART_EXPR:
2788     case IMAGPART_EXPR:
2789     case COMPONENT_REF:
2790       return lvalue_p (TREE_OPERAND (ref, 0));
2791
2792     case COMPOUND_LITERAL_EXPR:
2793     case STRING_CST:
2794       return 1;
2795
2796     case INDIRECT_REF:
2797     case ARRAY_REF:
2798     case VAR_DECL:
2799     case PARM_DECL:
2800     case RESULT_DECL:
2801     case ERROR_MARK:
2802       return (TREE_CODE (TREE_TYPE (ref)) != FUNCTION_TYPE
2803               && TREE_CODE (TREE_TYPE (ref)) != METHOD_TYPE);
2804
2805     case BIND_EXPR:
2806       return TREE_CODE (TREE_TYPE (ref)) == ARRAY_TYPE;
2807
2808     default:
2809       return 0;
2810     }
2811 }
2812 \f
2813 /* Give an error for storing in something that is 'const'.  */
2814
2815 static void
2816 readonly_error (tree arg, enum lvalue_use use)
2817 {
2818   gcc_assert (use == lv_assign || use == lv_increment || use == lv_decrement);
2819   /* Using this macro rather than (for example) arrays of messages
2820      ensures that all the format strings are checked at compile
2821      time.  */
2822 #define READONLY_MSG(A, I, D) (use == lv_assign                         \
2823                                ? (A)                                    \
2824                                : (use == lv_increment ? (I) : (D)))
2825   if (TREE_CODE (arg) == COMPONENT_REF)
2826     {
2827       if (TYPE_READONLY (TREE_TYPE (TREE_OPERAND (arg, 0))))
2828         readonly_error (TREE_OPERAND (arg, 0), use);
2829       else
2830         error (READONLY_MSG (N_("assignment of read-only member %qD"),
2831                              N_("increment of read-only member %qD"),
2832                              N_("decrement of read-only member %qD")),
2833                TREE_OPERAND (arg, 1));
2834     }
2835   else if (TREE_CODE (arg) == VAR_DECL)
2836     error (READONLY_MSG (N_("assignment of read-only variable %qD"),
2837                          N_("increment of read-only variable %qD"),
2838                          N_("decrement of read-only variable %qD")),
2839            arg);
2840   else
2841     error (READONLY_MSG (N_("assignment of read-only location"),
2842                          N_("increment of read-only location"),
2843                          N_("decrement of read-only location")));
2844 }
2845
2846
2847 /* Return nonzero if REF is an lvalue valid for this language;
2848    otherwise, print an error message and return zero.  USE says
2849    how the lvalue is being used and so selects the error message.  */
2850
2851 static int
2852 lvalue_or_else (tree ref, enum lvalue_use use)
2853 {
2854   int win = lvalue_p (ref);
2855
2856   if (!win)
2857     lvalue_error (use);
2858
2859   return win;
2860 }
2861 \f
2862 /* Mark EXP saying that we need to be able to take the
2863    address of it; it should not be allocated in a register.
2864    Returns true if successful.  */
2865
2866 bool
2867 c_mark_addressable (tree exp)
2868 {
2869   tree x = exp;
2870
2871   while (1)
2872     switch (TREE_CODE (x))
2873       {
2874       case COMPONENT_REF:
2875         if (DECL_C_BIT_FIELD (TREE_OPERAND (x, 1)))
2876           {
2877             error
2878               ("cannot take address of bit-field %qD", TREE_OPERAND (x, 1));
2879             return false;
2880           }
2881
2882         /* ... fall through ...  */
2883
2884       case ADDR_EXPR:
2885       case ARRAY_REF:
2886       case REALPART_EXPR:
2887       case IMAGPART_EXPR:
2888         x = TREE_OPERAND (x, 0);
2889         break;
2890
2891       case COMPOUND_LITERAL_EXPR:
2892       case CONSTRUCTOR:
2893         TREE_ADDRESSABLE (x) = 1;
2894         return true;
2895
2896       case VAR_DECL:
2897       case CONST_DECL:
2898       case PARM_DECL:
2899       case RESULT_DECL:
2900         if (C_DECL_REGISTER (x)
2901             && DECL_NONLOCAL (x))
2902           {
2903             if (TREE_PUBLIC (x) || TREE_STATIC (x) || DECL_EXTERNAL (x))
2904               {
2905                 error
2906                   ("global register variable %qD used in nested function", x);
2907                 return false;
2908               }
2909             pedwarn ("register variable %qD used in nested function", x);
2910           }
2911         else if (C_DECL_REGISTER (x))
2912           {
2913             if (TREE_PUBLIC (x) || TREE_STATIC (x) || DECL_EXTERNAL (x))
2914               error ("address of global register variable %qD requested", x);
2915             else
2916               error ("address of register variable %qD requested", x);
2917             return false;
2918           }
2919
2920         /* drops in */
2921       case FUNCTION_DECL:
2922         TREE_ADDRESSABLE (x) = 1;
2923         /* drops out */
2924       default:
2925         return true;
2926     }
2927 }
2928 \f
2929 /* Build and return a conditional expression IFEXP ? OP1 : OP2.  */
2930
2931 tree
2932 build_conditional_expr (tree ifexp, tree op1, tree op2)
2933 {
2934   tree type1;
2935   tree type2;
2936   enum tree_code code1;
2937   enum tree_code code2;
2938   tree result_type = NULL;
2939   tree orig_op1 = op1, orig_op2 = op2;
2940
2941   /* Promote both alternatives.  */
2942
2943   if (TREE_CODE (TREE_TYPE (op1)) != VOID_TYPE)
2944     op1 = default_conversion (op1);
2945   if (TREE_CODE (TREE_TYPE (op2)) != VOID_TYPE)
2946     op2 = default_conversion (op2);
2947
2948   if (TREE_CODE (ifexp) == ERROR_MARK
2949       || TREE_CODE (TREE_TYPE (op1)) == ERROR_MARK
2950       || TREE_CODE (TREE_TYPE (op2)) == ERROR_MARK)
2951     return error_mark_node;
2952
2953   type1 = TREE_TYPE (op1);
2954   code1 = TREE_CODE (type1);
2955   type2 = TREE_TYPE (op2);
2956   code2 = TREE_CODE (type2);
2957
2958   /* C90 does not permit non-lvalue arrays in conditional expressions.
2959      In C99 they will be pointers by now.  */
2960   if (code1 == ARRAY_TYPE || code2 == ARRAY_TYPE)
2961     {
2962       error ("non-lvalue array in conditional expression");
2963       return error_mark_node;
2964     }
2965
2966   /* Quickly detect the usual case where op1 and op2 have the same type
2967      after promotion.  */
2968   if (TYPE_MAIN_VARIANT (type1) == TYPE_MAIN_VARIANT (type2))
2969     {
2970       if (type1 == type2)
2971         result_type = type1;
2972       else
2973         result_type = TYPE_MAIN_VARIANT (type1);
2974     }
2975   else if ((code1 == INTEGER_TYPE || code1 == REAL_TYPE
2976             || code1 == COMPLEX_TYPE)
2977            && (code2 == INTEGER_TYPE || code2 == REAL_TYPE
2978                || code2 == COMPLEX_TYPE))
2979     {
2980       result_type = c_common_type (type1, type2);
2981
2982       /* If -Wsign-compare, warn here if type1 and type2 have
2983          different signedness.  We'll promote the signed to unsigned
2984          and later code won't know it used to be different.
2985          Do this check on the original types, so that explicit casts
2986          will be considered, but default promotions won't.  */
2987       if (warn_sign_compare && !skip_evaluation)
2988         {
2989           int unsigned_op1 = TYPE_UNSIGNED (TREE_TYPE (orig_op1));
2990           int unsigned_op2 = TYPE_UNSIGNED (TREE_TYPE (orig_op2));
2991
2992           if (unsigned_op1 ^ unsigned_op2)
2993             {
2994               /* Do not warn if the result type is signed, since the
2995                  signed type will only be chosen if it can represent
2996                  all the values of the unsigned type.  */
2997               if (!TYPE_UNSIGNED (result_type))
2998                 /* OK */;
2999               /* Do not warn if the signed quantity is an unsuffixed
3000                  integer literal (or some static constant expression
3001                  involving such literals) and it is non-negative.  */
3002               else if ((unsigned_op2 && tree_expr_nonnegative_p (op1))
3003                        || (unsigned_op1 && tree_expr_nonnegative_p (op2)))
3004                 /* OK */;
3005               else
3006                 warning (0, "signed and unsigned type in conditional expression");
3007             }
3008         }
3009     }
3010   else if (code1 == VOID_TYPE || code2 == VOID_TYPE)
3011     {
3012       if (pedantic && (code1 != VOID_TYPE || code2 != VOID_TYPE))
3013         pedwarn ("ISO C forbids conditional expr with only one void side");
3014       result_type = void_type_node;
3015     }
3016   else if (code1 == POINTER_TYPE && code2 == POINTER_TYPE)
3017     {
3018       if (comp_target_types (type1, type2, 1))
3019         result_type = common_pointer_type (type1, type2);
3020       else if (integer_zerop (op1) && TREE_TYPE (type1) == void_type_node
3021                && TREE_CODE (orig_op1) != NOP_EXPR)
3022         result_type = qualify_type (type2, type1);
3023       else if (integer_zerop (op2) && TREE_TYPE (type2) == void_type_node
3024                && TREE_CODE (orig_op2) != NOP_EXPR)
3025         result_type = qualify_type (type1, type2);
3026       else if (VOID_TYPE_P (TREE_TYPE (type1)))
3027         {
3028           if (pedantic && TREE_CODE (TREE_TYPE (type2)) == FUNCTION_TYPE)
3029             pedwarn ("ISO C forbids conditional expr between "
3030                      "%<void *%> and function pointer");
3031           result_type = build_pointer_type (qualify_type (TREE_TYPE (type1),
3032                                                           TREE_TYPE (type2)));
3033         }
3034       else if (VOID_TYPE_P (TREE_TYPE (type2)))
3035         {
3036           if (pedantic && TREE_CODE (TREE_TYPE (type1)) == FUNCTION_TYPE)
3037             pedwarn ("ISO C forbids conditional expr between "
3038                      "%<void *%> and function pointer");
3039           result_type = build_pointer_type (qualify_type (TREE_TYPE (type2),
3040                                                           TREE_TYPE (type1)));
3041         }
3042       else
3043         {
3044           pedwarn ("pointer type mismatch in conditional expression");
3045           result_type = build_pointer_type (void_type_node);
3046         }
3047     }
3048   else if (code1 == POINTER_TYPE && code2 == INTEGER_TYPE)
3049     {
3050       if (!integer_zerop (op2))
3051         pedwarn ("pointer/integer type mismatch in conditional expression");
3052       else
3053         {
3054           op2 = null_pointer_node;
3055         }
3056       result_type = type1;
3057     }
3058   else if (code2 == POINTER_TYPE && code1 == INTEGER_TYPE)
3059     {
3060       if (!integer_zerop (op1))
3061         pedwarn ("pointer/integer type mismatch in conditional expression");
3062       else
3063         {
3064           op1 = null_pointer_node;
3065         }
3066       result_type = type2;
3067     }
3068
3069   if (!result_type)
3070     {
3071       if (flag_cond_mismatch)
3072         result_type = void_type_node;
3073       else
3074         {
3075           error ("type mismatch in conditional expression");
3076           return error_mark_node;
3077         }
3078     }
3079
3080   /* Merge const and volatile flags of the incoming types.  */
3081   result_type
3082     = build_type_variant (result_type,
3083                           TREE_READONLY (op1) || TREE_READONLY (op2),
3084                           TREE_THIS_VOLATILE (op1) || TREE_THIS_VOLATILE (op2));
3085
3086   if (result_type != TREE_TYPE (op1))
3087     op1 = convert_and_check (result_type, op1);
3088   if (result_type != TREE_TYPE (op2))
3089     op2 = convert_and_check (result_type, op2);
3090
3091   if (TREE_CODE (ifexp) == INTEGER_CST)
3092     return non_lvalue (integer_zerop (ifexp) ? op2 : op1);
3093
3094   return fold (build3 (COND_EXPR, result_type, ifexp, op1, op2));
3095 }
3096 \f
3097 /* Return a compound expression that performs two expressions and
3098    returns the value of the second of them.  */
3099
3100 tree
3101 build_compound_expr (tree expr1, tree expr2)
3102 {
3103   /* Convert arrays and functions to pointers.  */
3104   expr2 = default_function_array_conversion (expr2);
3105
3106   if (!TREE_SIDE_EFFECTS (expr1))
3107     {
3108       /* The left-hand operand of a comma expression is like an expression
3109          statement: with -Wextra or -Wunused, we should warn if it doesn't have
3110          any side-effects, unless it was explicitly cast to (void).  */
3111       if (warn_unused_value)
3112         {
3113           if (VOID_TYPE_P (TREE_TYPE (expr1))
3114               && TREE_CODE (expr1) == CONVERT_EXPR)
3115             ; /* (void) a, b */
3116           else if (VOID_TYPE_P (TREE_TYPE (expr1))
3117                    && TREE_CODE (expr1) == COMPOUND_EXPR
3118                    && TREE_CODE (TREE_OPERAND (expr1, 1)) == CONVERT_EXPR)
3119             ; /* (void) a, (void) b, c */
3120           else
3121             warning (0, "left-hand operand of comma expression has no effect");
3122         }
3123     }
3124
3125   /* With -Wunused, we should also warn if the left-hand operand does have
3126      side-effects, but computes a value which is not used.  For example, in
3127      `foo() + bar(), baz()' the result of the `+' operator is not used,
3128      so we should issue a warning.  */
3129   else if (warn_unused_value)
3130     warn_if_unused_value (expr1, input_location);
3131
3132   return build2 (COMPOUND_EXPR, TREE_TYPE (expr2), expr1, expr2);
3133 }
3134
3135 /* Build an expression representing a cast to type TYPE of expression EXPR.  */
3136
3137 tree
3138 build_c_cast (tree type, tree expr)
3139 {
3140   tree value = expr;
3141
3142   if (type == error_mark_node || expr == error_mark_node)
3143     return error_mark_node;
3144
3145   /* The ObjC front-end uses TYPE_MAIN_VARIANT to tie together types differing
3146      only in <protocol> qualifications.  But when constructing cast expressions,
3147      the protocols do matter and must be kept around.  */
3148   if (objc_is_object_ptr (type) && objc_is_object_ptr (TREE_TYPE (expr)))
3149     return build1 (NOP_EXPR, type, expr);
3150
3151   type = TYPE_MAIN_VARIANT (type);
3152
3153   if (TREE_CODE (type) == ARRAY_TYPE)
3154     {
3155       error ("cast specifies array type");
3156       return error_mark_node;
3157     }
3158
3159   if (TREE_CODE (type) == FUNCTION_TYPE)
3160     {
3161       error ("cast specifies function type");
3162       return error_mark_node;
3163     }
3164
3165   if (type == TYPE_MAIN_VARIANT (TREE_TYPE (value)))
3166     {
3167       if (pedantic)
3168         {
3169           if (TREE_CODE (type) == RECORD_TYPE
3170               || TREE_CODE (type) == UNION_TYPE)
3171             pedwarn ("ISO C forbids casting nonscalar to the same type");
3172         }
3173     }
3174   else if (TREE_CODE (type) == UNION_TYPE)
3175     {
3176       tree field;
3177       value = default_function_array_conversion (value);
3178
3179       for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
3180         if (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (field)),
3181                        TYPE_MAIN_VARIANT (TREE_TYPE (value))))
3182           break;
3183
3184       if (field)
3185         {
3186           tree t;
3187
3188           if (pedantic)
3189             pedwarn ("ISO C forbids casts to union type");
3190           t = digest_init (type,
3191                            build_constructor (type,
3192                                               build_tree_list (field, value)),
3193                            true, 0);
3194           TREE_CONSTANT (t) = TREE_CONSTANT (value);
3195           TREE_INVARIANT (t) = TREE_INVARIANT (value);
3196           return t;
3197         }
3198       error ("cast to union type from type not present in union");
3199       return error_mark_node;
3200     }
3201   else
3202     {
3203       tree otype, ovalue;
3204
3205       /* If casting to void, avoid the error that would come
3206          from default_conversion in the case of a non-lvalue array.  */
3207       if (type == void_type_node)
3208         return build1 (CONVERT_EXPR, type, value);
3209
3210       /* Convert functions and arrays to pointers,
3211          but don't convert any other types.  */
3212       value = default_function_array_conversion (value);
3213       otype = TREE_TYPE (value);
3214
3215       /* Optionally warn about potentially worrisome casts.  */
3216
3217       if (warn_cast_qual
3218           && TREE_CODE (type) == POINTER_TYPE
3219           && TREE_CODE (otype) == POINTER_TYPE)
3220         {
3221           tree in_type = type;
3222           tree in_otype = otype;
3223           int added = 0;
3224           int discarded = 0;
3225
3226           /* Check that the qualifiers on IN_TYPE are a superset of
3227              the qualifiers of IN_OTYPE.  The outermost level of
3228              POINTER_TYPE nodes is uninteresting and we stop as soon
3229              as we hit a non-POINTER_TYPE node on either type.  */
3230           do
3231             {
3232               in_otype = TREE_TYPE (in_otype);
3233               in_type = TREE_TYPE (in_type);
3234
3235               /* GNU C allows cv-qualified function types.  'const'
3236                  means the function is very pure, 'volatile' means it
3237                  can't return.  We need to warn when such qualifiers
3238                  are added, not when they're taken away.  */
3239               if (TREE_CODE (in_otype) == FUNCTION_TYPE
3240                   && TREE_CODE (in_type) == FUNCTION_TYPE)
3241                 added |= (TYPE_QUALS (in_type) & ~TYPE_QUALS (in_otype));
3242               else
3243                 discarded |= (TYPE_QUALS (in_otype) & ~TYPE_QUALS (in_type));
3244             }
3245           while (TREE_CODE (in_type) == POINTER_TYPE
3246                  && TREE_CODE (in_otype) == POINTER_TYPE);
3247
3248           if (added)
3249             warning (0, "cast adds new qualifiers to function type");
3250
3251           if (discarded)
3252             /* There are qualifiers present in IN_OTYPE that are not
3253                present in IN_TYPE.  */
3254             warning (0, "cast discards qualifiers from pointer target type");
3255         }
3256
3257       /* Warn about possible alignment problems.  */
3258       if (STRICT_ALIGNMENT && warn_cast_align
3259           && TREE_CODE (type) == POINTER_TYPE
3260           && TREE_CODE (otype) == POINTER_TYPE
3261           && TREE_CODE (TREE_TYPE (otype)) != VOID_TYPE
3262           && TREE_CODE (TREE_TYPE (otype)) != FUNCTION_TYPE
3263           /* Don't warn about opaque types, where the actual alignment
3264              restriction is unknown.  */
3265           && !((TREE_CODE (TREE_TYPE (otype)) == UNION_TYPE
3266                 || TREE_CODE (TREE_TYPE (otype)) == RECORD_TYPE)
3267                && TYPE_MODE (TREE_TYPE (otype)) == VOIDmode)
3268           && TYPE_ALIGN (TREE_TYPE (type)) > TYPE_ALIGN (TREE_TYPE (otype)))
3269         warning (0, "cast increases required alignment of target type");
3270
3271       if (warn_pointer_to_int_cast
3272           && TREE_CODE (type) == INTEGER_TYPE
3273           && TREE_CODE (otype) == POINTER_TYPE
3274           && TYPE_PRECISION (type) != TYPE_PRECISION (otype)
3275           && !TREE_CONSTANT (value))
3276         warning (0, "cast from pointer to integer of different size");
3277
3278       if (warn_bad_function_cast
3279           && TREE_CODE (value) == CALL_EXPR
3280           && TREE_CODE (type) != TREE_CODE (otype))
3281         warning (0, "cast from function call of type %qT to non-matching "
3282                  "type %qT", otype, type);
3283
3284       if (warn_int_to_pointer_cast
3285           && TREE_CODE (type) == POINTER_TYPE
3286           && TREE_CODE (otype) == INTEGER_TYPE
3287           && TYPE_PRECISION (type) != TYPE_PRECISION (otype)
3288           /* Don't warn about converting any constant.  */
3289           && !TREE_CONSTANT (value))
3290         warning (0, "cast to pointer from integer of different size");
3291
3292       if (TREE_CODE (type) == POINTER_TYPE
3293           && TREE_CODE (otype) == POINTER_TYPE
3294           && TREE_CODE (expr) == ADDR_EXPR
3295           && DECL_P (TREE_OPERAND (expr, 0))
3296           && flag_strict_aliasing && warn_strict_aliasing
3297           && !VOID_TYPE_P (TREE_TYPE (type)))
3298         {
3299           /* Casting the address of a decl to non void pointer. Warn
3300              if the cast breaks type based aliasing.  */
3301           if (!COMPLETE_TYPE_P (TREE_TYPE (type)))
3302             warning (0, "type-punning to incomplete type might break strict-aliasing rules");
3303           else
3304             {
3305               HOST_WIDE_INT set1 = get_alias_set (TREE_TYPE (TREE_OPERAND (expr, 0)));
3306               HOST_WIDE_INT set2 = get_alias_set (TREE_TYPE (type));
3307
3308               if (!alias_sets_conflict_p (set1, set2))
3309                 warning (0, "dereferencing type-punned pointer will break strict-aliasing rules");
3310               else if (warn_strict_aliasing > 1
3311                        && !alias_sets_might_conflict_p (set1, set2))
3312                 warning (0, "dereferencing type-punned pointer might break strict-aliasing rules");
3313             }
3314         }
3315
3316       /* If pedantic, warn for conversions between function and object
3317          pointer types, except for converting a null pointer constant
3318          to function pointer type.  */
3319       if (pedantic
3320           && TREE_CODE (type) == POINTER_TYPE
3321           && TREE_CODE (otype) == POINTER_TYPE
3322           && TREE_CODE (TREE_TYPE (otype)) == FUNCTION_TYPE
3323           && TREE_CODE (TREE_TYPE (type)) != FUNCTION_TYPE)
3324         pedwarn ("ISO C forbids conversion of function pointer to object pointer type");
3325
3326       if (pedantic
3327           && TREE_CODE (type) == POINTER_TYPE
3328           && TREE_CODE (otype) == POINTER_TYPE
3329           && TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE
3330           && TREE_CODE (TREE_TYPE (otype)) != FUNCTION_TYPE
3331           && !(integer_zerop (value) && TREE_TYPE (otype) == void_type_node
3332                && TREE_CODE (expr) != NOP_EXPR))
3333         pedwarn ("ISO C forbids conversion of object pointer to function pointer type");
3334
3335       ovalue = value;
3336       value = convert (type, value);
3337
3338       /* Ignore any integer overflow caused by the cast.  */
3339       if (TREE_CODE (value) == INTEGER_CST)
3340         {
3341           if (EXPR_P (ovalue))
3342             /* If OVALUE had overflow set, then so will VALUE, so it
3343                is safe to overwrite.  */
3344             TREE_OVERFLOW (value) = TREE_OVERFLOW (ovalue);
3345           else
3346             TREE_OVERFLOW (value) = 0;
3347
3348           if (CONSTANT_CLASS_P (ovalue))
3349             /* Similarly, constant_overflow cannot have become
3350                cleared.  */
3351             TREE_CONSTANT_OVERFLOW (value) = TREE_CONSTANT_OVERFLOW (ovalue);
3352         }
3353     }
3354
3355   /* Don't let a cast be an lvalue.  */
3356   if (value == expr)
3357     value = non_lvalue (value);
3358
3359   return value;
3360 }
3361
3362 /* Interpret a cast of expression EXPR to type TYPE.  */
3363 tree
3364 c_cast_expr (struct c_type_name *type_name, tree expr)
3365 {
3366   tree type;
3367   int saved_wsp = warn_strict_prototypes;
3368
3369   /* This avoids warnings about unprototyped casts on
3370      integers.  E.g. "#define SIG_DFL (void(*)())0".  */
3371   if (TREE_CODE (expr) == INTEGER_CST)
3372     warn_strict_prototypes = 0;
3373   type = groktypename (type_name);
3374   warn_strict_prototypes = saved_wsp;
3375
3376   return build_c_cast (type, expr);
3377 }
3378
3379 \f
3380 /* Build an assignment expression of lvalue LHS from value RHS.
3381    MODIFYCODE is the code for a binary operator that we use
3382    to combine the old value of LHS with RHS to get the new value.
3383    Or else MODIFYCODE is NOP_EXPR meaning do a simple assignment.  */
3384
3385 tree
3386 build_modify_expr (tree lhs, enum tree_code modifycode, tree rhs)
3387 {
3388   tree result;
3389   tree newrhs;
3390   tree lhstype = TREE_TYPE (lhs);
3391   tree olhstype = lhstype;
3392
3393   /* Types that aren't fully specified cannot be used in assignments.  */
3394   lhs = require_complete_type (lhs);
3395
3396   /* Avoid duplicate error messages from operands that had errors.  */
3397   if (TREE_CODE (lhs) == ERROR_MARK || TREE_CODE (rhs) == ERROR_MARK)
3398     return error_mark_node;
3399
3400   STRIP_TYPE_NOPS (rhs);
3401
3402   newrhs = rhs;
3403
3404   /* If a binary op has been requested, combine the old LHS value with the RHS
3405      producing the value we should actually store into the LHS.  */
3406
3407   if (modifycode != NOP_EXPR)
3408     {
3409       lhs = stabilize_reference (lhs);
3410       newrhs = build_binary_op (modifycode, lhs, rhs, 1);
3411     }
3412
3413   if (!lvalue_or_else (lhs, lv_assign))
3414     return error_mark_node;
3415
3416   /* Give an error for storing in something that is 'const'.  */
3417
3418   if (TREE_READONLY (lhs) || TYPE_READONLY (lhstype)
3419       || ((TREE_CODE (lhstype) == RECORD_TYPE
3420            || TREE_CODE (lhstype) == UNION_TYPE)
3421           && C_TYPE_FIELDS_READONLY (lhstype)))
3422     readonly_error (lhs, lv_assign);
3423
3424   /* If storing into a structure or union member,
3425      it has probably been given type `int'.
3426      Compute the type that would go with
3427      the actual amount of storage the member occupies.  */
3428
3429   if (TREE_CODE (lhs) == COMPONENT_REF
3430       && (TREE_CODE (lhstype) == INTEGER_TYPE
3431           || TREE_CODE (lhstype) == BOOLEAN_TYPE
3432           || TREE_CODE (lhstype) == REAL_TYPE
3433           || TREE_CODE (lhstype) == ENUMERAL_TYPE))
3434     lhstype = TREE_TYPE (get_unwidened (lhs, 0));
3435
3436   /* If storing in a field that is in actuality a short or narrower than one,
3437      we must store in the field in its actual type.  */
3438
3439   if (lhstype != TREE_TYPE (lhs))
3440     {
3441       lhs = copy_node (lhs);
3442       TREE_TYPE (lhs) = lhstype;
3443     }
3444
3445   /* Convert new value to destination type.  */
3446
3447   newrhs = convert_for_assignment (lhstype, newrhs, ic_assign,
3448                                    NULL_TREE, NULL_TREE, 0);
3449   if (TREE_CODE (newrhs) == ERROR_MARK)
3450     return error_mark_node;
3451
3452   /* Scan operands.  */
3453
3454   result = build2 (MODIFY_EXPR, lhstype, lhs, newrhs);
3455   TREE_SIDE_EFFECTS (result) = 1;
3456
3457   /* If we got the LHS in a different type for storing in,
3458      convert the result back to the nominal type of LHS
3459      so that the value we return always has the same type
3460      as the LHS argument.  */
3461
3462   if (olhstype == TREE_TYPE (result))
3463     return result;
3464   return convert_for_assignment (olhstype, result, ic_assign,
3465                                  NULL_TREE, NULL_TREE, 0);
3466 }
3467 \f
3468 /* Convert value RHS to type TYPE as preparation for an assignment
3469    to an lvalue of type TYPE.
3470    The real work of conversion is done by `convert'.
3471    The purpose of this function is to generate error messages
3472    for assignments that are not allowed in C.
3473    ERRTYPE says whether it is argument passing, assignment,
3474    initialization or return.
3475
3476    FUNCTION is a tree for the function being called.
3477    PARMNUM is the number of the argument, for printing in error messages.  */
3478
3479 static tree
3480 convert_for_assignment (tree type, tree rhs, enum impl_conv errtype,
3481                         tree fundecl, tree function, int parmnum)
3482 {
3483   enum tree_code codel = TREE_CODE (type);
3484   tree rhstype;
3485   enum tree_code coder;
3486   tree rname = NULL_TREE;
3487
3488   if (errtype == ic_argpass || errtype == ic_argpass_nonproto)
3489     {
3490       tree selector;
3491       /* Change pointer to function to the function itself for
3492          diagnostics.  */
3493       if (TREE_CODE (function) == ADDR_EXPR
3494           && TREE_CODE (TREE_OPERAND (function, 0)) == FUNCTION_DECL)
3495         function = TREE_OPERAND (function, 0);
3496
3497       /* Handle an ObjC selector specially for diagnostics.  */
3498       selector = objc_message_selector ();
3499       rname = function;
3500       if (selector && parmnum > 2)
3501         {
3502           rname = selector;
3503           parmnum -= 2;
3504         }
3505     }
3506
3507   /* This macro is used to emit diagnostics to ensure that all format
3508      strings are complete sentences, visible to gettext and checked at
3509      compile time.  */
3510 #define WARN_FOR_ASSIGNMENT(AR, AS, IN, RE)     \
3511   do {                                          \
3512     switch (errtype)                            \
3513       {                                         \
3514       case ic_argpass:                          \
3515         pedwarn (AR, parmnum, rname);           \
3516         break;                                  \
3517       case ic_argpass_nonproto:                 \
3518         warning (0, AR, parmnum, rname);                \
3519         break;                                  \
3520       case ic_assign:                           \
3521         pedwarn (AS);                           \
3522         break;                                  \
3523       case ic_init:                             \
3524         pedwarn (IN);                           \
3525         break;                                  \
3526       case ic_return:                           \
3527         pedwarn (RE);                           \
3528         break;                                  \
3529       default:                                  \
3530         gcc_unreachable ();                     \
3531       }                                         \
3532   } while (0)
3533
3534   STRIP_TYPE_NOPS (rhs);
3535
3536   if (TREE_CODE (TREE_TYPE (rhs)) == ARRAY_TYPE
3537       || TREE_CODE (TREE_TYPE (rhs)) == FUNCTION_TYPE)
3538     rhs = default_conversion (rhs);
3539   else if (optimize && TREE_CODE (rhs) == VAR_DECL)
3540     rhs = decl_constant_value_for_broken_optimization (rhs);
3541
3542   rhstype = TREE_TYPE (rhs);
3543   coder = TREE_CODE (rhstype);
3544
3545   if (coder == ERROR_MARK)
3546     return error_mark_node;
3547
3548   if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (rhstype))
3549     {
3550       overflow_warning (rhs);
3551       /* Check for Objective-C protocols.  This will automatically
3552          issue a warning if there are protocol violations.  No need to
3553          use the return value.  */
3554       if (c_dialect_objc ())
3555         objc_comptypes (type, rhstype, 0);
3556       return rhs;
3557     }
3558
3559   if (coder == VOID_TYPE)
3560     {
3561       /* Except for passing an argument to an unprototyped function,
3562          this is a constraint violation.  When passing an argument to
3563          an unprototyped function, it is compile-time undefined;
3564          making it a constraint in that case was rejected in
3565          DR#252.  */
3566       error ("void value not ignored as it ought to be");
3567       return error_mark_node;
3568     }
3569   /* A type converts to a reference to it.
3570      This code doesn't fully support references, it's just for the
3571      special case of va_start and va_copy.  */
3572   if (codel == REFERENCE_TYPE
3573       && comptypes (TREE_TYPE (type), TREE_TYPE (rhs)) == 1)
3574     {
3575       if (!lvalue_p (rhs))
3576         {
3577           error ("cannot pass rvalue to reference parameter");
3578           return error_mark_node;
3579         }
3580       if (!c_mark_addressable (rhs))
3581         return error_mark_node;
3582       rhs = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (rhs)), rhs);
3583
3584       /* We already know that these two types are compatible, but they
3585          may not be exactly identical.  In fact, `TREE_TYPE (type)' is
3586          likely to be __builtin_va_list and `TREE_TYPE (rhs)' is
3587          likely to be va_list, a typedef to __builtin_va_list, which
3588          is different enough that it will cause problems later.  */
3589       if (TREE_TYPE (TREE_TYPE (rhs)) != TREE_TYPE (type))
3590         rhs = build1 (NOP_EXPR, build_pointer_type (TREE_TYPE (type)), rhs);
3591
3592       rhs = build1 (NOP_EXPR, type, rhs);
3593       return rhs;
3594     }
3595   /* Some types can interconvert without explicit casts.  */
3596   else if (codel == VECTOR_TYPE && coder == VECTOR_TYPE
3597            && vector_types_convertible_p (type, TREE_TYPE (rhs)))
3598     return convert (type, rhs);
3599   /* Arithmetic types all interconvert, and enum is treated like int.  */
3600   else if ((codel == INTEGER_TYPE || codel == REAL_TYPE
3601             || codel == ENUMERAL_TYPE || codel == COMPLEX_TYPE
3602             || codel == BOOLEAN_TYPE)
3603            && (coder == INTEGER_TYPE || coder == REAL_TYPE
3604                || coder == ENUMERAL_TYPE || coder == COMPLEX_TYPE
3605                || coder == BOOLEAN_TYPE))
3606     return convert_and_check (type, rhs);
3607
3608   /* Conversion to a transparent union from its member types.
3609      This applies only to function arguments.  */
3610   else if (codel == UNION_TYPE && TYPE_TRANSPARENT_UNION (type)
3611            && (errtype == ic_argpass || errtype == ic_argpass_nonproto))
3612     {
3613       tree memb_types;
3614       tree marginal_memb_type = 0;
3615
3616       for (memb_types = TYPE_FIELDS (type); memb_types;
3617            memb_types = TREE_CHAIN (memb_types))
3618         {
3619           tree memb_type = TREE_TYPE (memb_types);
3620
3621           if (comptypes (TYPE_MAIN_VARIANT (memb_type),
3622                          TYPE_MAIN_VARIANT (rhstype)))
3623             break;
3624
3625           if (TREE_CODE (memb_type) != POINTER_TYPE)
3626             continue;
3627
3628           if (coder == POINTER_TYPE)
3629             {
3630               tree ttl = TREE_TYPE (memb_type);
3631               tree ttr = TREE_TYPE (rhstype);
3632
3633               /* Any non-function converts to a [const][volatile] void *
3634                  and vice versa; otherwise, targets must be the same.
3635                  Meanwhile, the lhs target must have all the qualifiers of
3636                  the rhs.  */
3637               if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
3638                   || comp_target_types (memb_type, rhstype, 0))
3639                 {
3640                   /* If this type won't generate any warnings, use it.  */
3641                   if (TYPE_QUALS (ttl) == TYPE_QUALS (ttr)
3642                       || ((TREE_CODE (ttr) == FUNCTION_TYPE
3643                            && TREE_CODE (ttl) == FUNCTION_TYPE)
3644                           ? ((TYPE_QUALS (ttl) | TYPE_QUALS (ttr))
3645                              == TYPE_QUALS (ttr))
3646                           : ((TYPE_QUALS (ttl) | TYPE_QUALS (ttr))
3647                              == TYPE_QUALS (ttl))))
3648                     break;
3649
3650                   /* Keep looking for a better type, but remember this one.  */
3651                   if (!marginal_memb_type)
3652                     marginal_memb_type = memb_type;
3653                 }
3654             }
3655
3656           /* Can convert integer zero to any pointer type.  */
3657           if (integer_zerop (rhs)
3658               || (TREE_CODE (rhs) == NOP_EXPR
3659                   && integer_zerop (TREE_OPERAND (rhs, 0))))
3660             {
3661               rhs = null_pointer_node;
3662               break;
3663             }
3664         }
3665
3666       if (memb_types || marginal_memb_type)
3667         {
3668           if (!memb_types)
3669             {
3670               /* We have only a marginally acceptable member type;
3671                  it needs a warning.  */
3672               tree ttl = TREE_TYPE (marginal_memb_type);
3673               tree ttr = TREE_TYPE (rhstype);
3674
3675               /* Const and volatile mean something different for function
3676                  types, so the usual warnings are not appropriate.  */
3677               if (TREE_CODE (ttr) == FUNCTION_TYPE
3678                   && TREE_CODE (ttl) == FUNCTION_TYPE)
3679                 {
3680                   /* Because const and volatile on functions are
3681                      restrictions that say the function will not do
3682                      certain things, it is okay to use a const or volatile
3683                      function where an ordinary one is wanted, but not
3684                      vice-versa.  */
3685                   if (TYPE_QUALS (ttl) & ~TYPE_QUALS (ttr))
3686                     WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE "
3687                                             "makes qualified function "
3688                                             "pointer from unqualified"),
3689                                          N_("assignment makes qualified "
3690                                             "function pointer from "
3691                                             "unqualified"),
3692                                          N_("initialization makes qualified "
3693                                             "function pointer from "
3694                                             "unqualified"),
3695                                          N_("return makes qualified function "
3696                                             "pointer from unqualified"));
3697                 }
3698               else if (TYPE_QUALS (ttr) & ~TYPE_QUALS (ttl))
3699                 WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE discards "
3700                                         "qualifiers from pointer target type"),
3701                                      N_("assignment discards qualifiers "
3702                                         "from pointer target type"),
3703                                      N_("initialization discards qualifiers "
3704                                         "from pointer target type"),
3705                                      N_("return discards qualifiers from "
3706                                         "pointer target type"));
3707             }
3708
3709           if (pedantic && !DECL_IN_SYSTEM_HEADER (fundecl))
3710             pedwarn ("ISO C prohibits argument conversion to union type");
3711
3712           return build1 (NOP_EXPR, type, rhs);
3713         }
3714     }
3715
3716   /* Conversions among pointers */
3717   else if ((codel == POINTER_TYPE || codel == REFERENCE_TYPE)
3718            && (coder == codel))
3719     {
3720       tree ttl = TREE_TYPE (type);
3721       tree ttr = TREE_TYPE (rhstype);
3722       tree mvl = ttl;
3723       tree mvr = ttr;
3724       bool is_opaque_pointer;
3725       int target_cmp = 0;   /* Cache comp_target_types () result.  */
3726
3727       if (TREE_CODE (mvl) != ARRAY_TYPE)
3728         mvl = TYPE_MAIN_VARIANT (mvl);
3729       if (TREE_CODE (mvr) != ARRAY_TYPE)
3730         mvr = TYPE_MAIN_VARIANT (mvr);
3731       /* Opaque pointers are treated like void pointers.  */
3732       is_opaque_pointer = (targetm.vector_opaque_p (type)
3733                            || targetm.vector_opaque_p (rhstype))
3734         && TREE_CODE (ttl) == VECTOR_TYPE
3735         && TREE_CODE (ttr) == VECTOR_TYPE;
3736
3737       /* Any non-function converts to a [const][volatile] void *
3738          and vice versa; otherwise, targets must be the same.
3739          Meanwhile, the lhs target must have all the qualifiers of the rhs.  */
3740       if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
3741           || (target_cmp = comp_target_types (type, rhstype, 0))
3742           || is_opaque_pointer
3743           || (c_common_unsigned_type (mvl)
3744               == c_common_unsigned_type (mvr)))
3745         {
3746           if (pedantic
3747               && ((VOID_TYPE_P (ttl) && TREE_CODE (ttr) == FUNCTION_TYPE)
3748                   ||
3749                   (VOID_TYPE_P (ttr)
3750                    /* Check TREE_CODE to catch cases like (void *) (char *) 0
3751                       which are not ANSI null ptr constants.  */
3752                    && (!integer_zerop (rhs) || TREE_CODE (rhs) == NOP_EXPR)
3753                    && TREE_CODE (ttl) == FUNCTION_TYPE)))
3754             WARN_FOR_ASSIGNMENT (N_("ISO C forbids passing argument %d of "
3755                                     "%qE between function pointer "
3756                                     "and %<void *%>"),
3757                                  N_("ISO C forbids assignment between "
3758                                     "function pointer and %<void *%>"),
3759                                  N_("ISO C forbids initialization between "
3760                                     "function pointer and %<void *%>"),
3761                                  N_("ISO C forbids return between function "
3762                                     "pointer and %<void *%>"));
3763           /* Const and volatile mean something different for function types,
3764              so the usual warnings are not appropriate.  */
3765           else if (TREE_CODE (ttr) != FUNCTION_TYPE
3766                    && TREE_CODE (ttl) != FUNCTION_TYPE)
3767             {
3768               if (TYPE_QUALS (ttr) & ~TYPE_QUALS (ttl))
3769                 WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE discards "
3770                                         "qualifiers from pointer target type"),
3771                                      N_("assignment discards qualifiers "
3772                                         "from pointer target type"),
3773                                      N_("initialization discards qualifiers "
3774                                         "from pointer target type"),
3775                                      N_("return discards qualifiers from "
3776                                         "pointer target type"));
3777               /* If this is not a case of ignoring a mismatch in signedness,
3778                  no warning.  */
3779               else if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
3780                        || target_cmp)
3781                 ;
3782               /* If there is a mismatch, do warn.  */
3783               else if (warn_pointer_sign)
3784                 WARN_FOR_ASSIGNMENT (N_("pointer targets in passing argument "
3785                                         "%d of %qE differ in signedness"),
3786                                      N_("pointer targets in assignment "
3787                                         "differ in signedness"),
3788                                      N_("pointer targets in initialization "
3789                                         "differ in signedness"),
3790                                      N_("pointer targets in return differ "
3791                                         "in signedness"));
3792             }
3793           else if (TREE_CODE (ttl) == FUNCTION_TYPE
3794                    && TREE_CODE (ttr) == FUNCTION_TYPE)
3795             {
3796               /* Because const and volatile on functions are restrictions
3797                  that say the function will not do certain things,
3798                  it is okay to use a const or volatile function
3799                  where an ordinary one is wanted, but not vice-versa.  */
3800               if (TYPE_QUALS (ttl) & ~TYPE_QUALS (ttr))
3801                 WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE makes "
3802                                         "qualified function pointer "
3803                                         "from unqualified"),
3804                                      N_("assignment makes qualified function "
3805                                         "pointer from unqualified"),
3806                                      N_("initialization makes qualified "
3807                                         "function pointer from unqualified"),
3808                                      N_("return makes qualified function "
3809                                         "pointer from unqualified"));
3810             }
3811         }
3812       else
3813         WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE from "
3814                                 "incompatible pointer type"),
3815                              N_("assignment from incompatible pointer type"),
3816                              N_("initialization from incompatible "
3817                                 "pointer type"),
3818                              N_("return from incompatible pointer type"));
3819       return convert (type, rhs);
3820     }
3821   else if (codel == POINTER_TYPE && coder == ARRAY_TYPE)
3822     {
3823       /* ??? This should not be an error when inlining calls to
3824          unprototyped functions.  */
3825       error ("invalid use of non-lvalue array");
3826       return error_mark_node;
3827     }
3828   else if (codel == POINTER_TYPE && coder == INTEGER_TYPE)
3829     {
3830       /* An explicit constant 0 can convert to a pointer,
3831          or one that results from arithmetic, even including
3832          a cast to integer type.  */
3833       if (!(TREE_CODE (rhs) == INTEGER_CST && integer_zerop (rhs))
3834           &&
3835           !(TREE_CODE (rhs) == NOP_EXPR
3836             && TREE_CODE (TREE_TYPE (rhs)) == INTEGER_TYPE
3837             && TREE_CODE (TREE_OPERAND (rhs, 0)) == INTEGER_CST
3838             && integer_zerop (TREE_OPERAND (rhs, 0))))
3839         WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE makes "
3840                                 "pointer from integer without a cast"),
3841                              N_("assignment makes pointer from integer "
3842                                 "without a cast"),
3843                              N_("initialization makes pointer from "
3844                                 "integer without a cast"),
3845                              N_("return makes pointer from integer "
3846                                 "without a cast"));
3847
3848       return convert (type, rhs);
3849     }
3850   else if (codel == INTEGER_TYPE && coder == POINTER_TYPE)
3851     {
3852       WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE makes integer "
3853                               "from pointer without a cast"),
3854                            N_("assignment makes integer from pointer "
3855                               "without a cast"),
3856                            N_("initialization makes integer from pointer "
3857                               "without a cast"),
3858                            N_("return makes integer from pointer "
3859                               "without a cast"));
3860       return convert (type, rhs);
3861     }
3862   else if (codel == BOOLEAN_TYPE && coder == POINTER_TYPE)
3863     return convert (type, rhs);
3864
3865   switch (errtype)
3866     {
3867     case ic_argpass:
3868     case ic_argpass_nonproto:
3869       /* ??? This should not be an error when inlining calls to
3870          unprototyped functions.  */
3871       error ("incompatible type for argument %d of %qE", parmnum, rname);
3872       break;
3873     case ic_assign:
3874       error ("incompatible types in assignment");
3875       break;
3876     case ic_init:
3877       error ("incompatible types in initialization");
3878       break;
3879     case ic_return:
3880       error ("incompatible types in return");
3881       break;
3882     default:
3883       gcc_unreachable ();
3884     }
3885
3886   return error_mark_node;
3887 }
3888
3889 /* Convert VALUE for assignment into inlined parameter PARM.  ARGNUM
3890    is used for error and waring reporting and indicates which argument
3891    is being processed.  */
3892
3893 tree
3894 c_convert_parm_for_inlining (tree parm, tree value, tree fn, int argnum)
3895 {
3896   tree ret, type;
3897
3898   /* If FN was prototyped, the value has been converted already
3899      in convert_arguments.  */
3900   if (!value || TYPE_ARG_TYPES (TREE_TYPE (fn)))
3901     return value;
3902
3903   type = TREE_TYPE (parm);
3904   ret = convert_for_assignment (type, value,
3905                                 ic_argpass_nonproto, fn,
3906                                 fn, argnum);
3907   if (targetm.calls.promote_prototypes (TREE_TYPE (fn))
3908       && INTEGRAL_TYPE_P (type)
3909       && (TYPE_PRECISION (type) < TYPE_PRECISION (integer_type_node)))
3910     ret = default_conversion (ret);
3911   return ret;
3912 }
3913 \f
3914 /* If VALUE is a compound expr all of whose expressions are constant, then
3915    return its value.  Otherwise, return error_mark_node.
3916
3917    This is for handling COMPOUND_EXPRs as initializer elements
3918    which is allowed with a warning when -pedantic is specified.  */
3919
3920 static tree
3921 valid_compound_expr_initializer (tree value, tree endtype)
3922 {
3923   if (TREE_CODE (value) == COMPOUND_EXPR)
3924     {
3925       if (valid_compound_expr_initializer (TREE_OPERAND (value, 0), endtype)
3926           == error_mark_node)
3927         return error_mark_node;
3928       return valid_compound_expr_initializer (TREE_OPERAND (value, 1),
3929                                               endtype);
3930     }
3931   else if (!initializer_constant_valid_p (value, endtype))
3932     return error_mark_node;
3933   else
3934     return value;
3935 }
3936 \f
3937 /* Perform appropriate conversions on the initial value of a variable,
3938    store it in the declaration DECL,
3939    and print any error messages that are appropriate.
3940    If the init is invalid, store an ERROR_MARK.  */
3941
3942 void
3943 store_init_value (tree decl, tree init)
3944 {
3945   tree value, type;
3946
3947   /* If variable's type was invalidly declared, just ignore it.  */
3948
3949   type = TREE_TYPE (decl);
3950   if (TREE_CODE (type) == ERROR_MARK)
3951     return;
3952
3953   /* Digest the specified initializer into an expression.  */
3954
3955   value = digest_init (type, init, true, TREE_STATIC (decl));
3956
3957   /* Store the expression if valid; else report error.  */
3958
3959   if (warn_traditional && !in_system_header
3960       && AGGREGATE_TYPE_P (TREE_TYPE (decl)) && !TREE_STATIC (decl))
3961     warning (0, "traditional C rejects automatic aggregate initialization");
3962
3963   DECL_INITIAL (decl) = value;
3964
3965   /* ANSI wants warnings about out-of-range constant initializers.  */
3966   STRIP_TYPE_NOPS (value);
3967   constant_expression_warning (value);
3968
3969   /* Check if we need to set array size from compound literal size.  */
3970   if (TREE_CODE (type) == ARRAY_TYPE
3971       && TYPE_DOMAIN (type) == 0
3972       && value != error_mark_node)
3973     {
3974       tree inside_init = init;
3975
3976       STRIP_TYPE_NOPS (inside_init);
3977       inside_init = fold (inside_init);
3978
3979       if (TREE_CODE (inside_init) == COMPOUND_LITERAL_EXPR)
3980         {
3981           tree decl = COMPOUND_LITERAL_EXPR_DECL (inside_init);
3982
3983           if (TYPE_DOMAIN (TREE_TYPE (decl)))
3984             {
3985               /* For int foo[] = (int [3]){1}; we need to set array size
3986                  now since later on array initializer will be just the
3987                  brace enclosed list of the compound literal.  */
3988               TYPE_DOMAIN (type) = TYPE_DOMAIN (TREE_TYPE (decl));
3989               layout_type (type);
3990               layout_decl (decl, 0);
3991             }
3992         }
3993     }
3994 }
3995 \f
3996 /* Methods for storing and printing names for error messages.  */
3997
3998 /* Implement a spelling stack that allows components of a name to be pushed
3999    and popped.  Each element on the stack is this structure.  */
4000
4001 struct spelling
4002 {
4003   int kind;
4004   union
4005     {
4006       int i;
4007       const char *s;
4008     } u;
4009 };
4010
4011 #define SPELLING_STRING 1
4012 #define SPELLING_MEMBER 2
4013 #define SPELLING_BOUNDS 3
4014
4015 static struct spelling *spelling;       /* Next stack element (unused).  */
4016 static struct spelling *spelling_base;  /* Spelling stack base.  */
4017 static int spelling_size;               /* Size of the spelling stack.  */
4018
4019 /* Macros to save and restore the spelling stack around push_... functions.
4020    Alternative to SAVE_SPELLING_STACK.  */
4021
4022 #define SPELLING_DEPTH() (spelling - spelling_base)
4023 #define RESTORE_SPELLING_DEPTH(DEPTH) (spelling = spelling_base + (DEPTH))
4024
4025 /* Push an element on the spelling stack with type KIND and assign VALUE
4026    to MEMBER.  */
4027
4028 #define PUSH_SPELLING(KIND, VALUE, MEMBER)                              \
4029 {                                                                       \
4030   int depth = SPELLING_DEPTH ();                                        \
4031                                                                         \
4032   if (depth >= spelling_size)                                           \
4033     {                                                                   \
4034       spelling_size += 10;                                              \
4035       spelling_base = XRESIZEVEC (struct spelling, spelling_base,       \
4036                                   spelling_size);                       \
4037       RESTORE_SPELLING_DEPTH (depth);                                   \
4038     }                                                                   \
4039                                                                         \
4040   spelling->kind = (KIND);                                              \
4041   spelling->MEMBER = (VALUE);                                           \
4042   spelling++;                                                           \
4043 }
4044
4045 /* Push STRING on the stack.  Printed literally.  */
4046
4047 static void
4048 push_string (const char *string)
4049 {
4050   PUSH_SPELLING (SPELLING_STRING, string, u.s);
4051 }
4052
4053 /* Push a member name on the stack.  Printed as '.' STRING.  */
4054
4055 static void
4056 push_member_name (tree decl)
4057 {
4058   const char *const string
4059     = DECL_NAME (decl) ? IDENTIFIER_POINTER (DECL_NAME (decl)) : "<anonymous>";
4060   PUSH_SPELLING (SPELLING_MEMBER, string, u.s);
4061 }
4062
4063 /* Push an array bounds on the stack.  Printed as [BOUNDS].  */
4064
4065 static void
4066 push_array_bounds (int bounds)
4067 {
4068   PUSH_SPELLING (SPELLING_BOUNDS, bounds, u.i);
4069 }
4070
4071 /* Compute the maximum size in bytes of the printed spelling.  */
4072
4073 static int
4074 spelling_length (void)
4075 {
4076   int size = 0;
4077   struct spelling *p;
4078
4079   for (p = spelling_base; p < spelling; p++)
4080     {
4081       if (p->kind == SPELLING_BOUNDS)
4082         size += 25;
4083       else
4084         size += strlen (p->u.s) + 1;
4085     }
4086
4087   return size;
4088 }
4089
4090 /* Print the spelling to BUFFER and return it.  */
4091
4092 static char *
4093 print_spelling (char *buffer)
4094 {
4095   char *d = buffer;
4096   struct spelling *p;
4097
4098   for (p = spelling_base; p < spelling; p++)
4099     if (p->kind == SPELLING_BOUNDS)
4100       {
4101         sprintf (d, "[%d]", p->u.i);
4102         d += strlen (d);
4103       }
4104     else
4105       {
4106         const char *s;
4107         if (p->kind == SPELLING_MEMBER)
4108           *d++ = '.';
4109         for (s = p->u.s; (*d = *s++); d++)
4110           ;
4111       }
4112   *d++ = '\0';
4113   return buffer;
4114 }
4115
4116 /* Issue an error message for a bad initializer component.
4117    MSGID identifies the message.
4118    The component name is taken from the spelling stack.  */
4119
4120 void
4121 error_init (const char *msgid)
4122 {
4123   char *ofwhat;
4124
4125   error ("%s", _(msgid));
4126   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4127   if (*ofwhat)
4128     error ("(near initialization for %qs)", ofwhat);
4129 }
4130
4131 /* Issue a pedantic warning for a bad initializer component.
4132    MSGID identifies the message.
4133    The component name is taken from the spelling stack.  */
4134
4135 void
4136 pedwarn_init (const char *msgid)
4137 {
4138   char *ofwhat;
4139
4140   pedwarn ("%s", _(msgid));
4141   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4142   if (*ofwhat)
4143     pedwarn ("(near initialization for %qs)", ofwhat);
4144 }
4145
4146 /* Issue a warning for a bad initializer component.
4147    MSGID identifies the message.
4148    The component name is taken from the spelling stack.  */
4149
4150 static void
4151 warning_init (const char *msgid)
4152 {
4153   char *ofwhat;
4154
4155   warning (0, "%s", _(msgid));
4156   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4157   if (*ofwhat)
4158     warning (0, "(near initialization for %qs)", ofwhat);
4159 }
4160 \f
4161 /* If TYPE is an array type and EXPR is a parenthesized string
4162    constant, warn if pedantic that EXPR is being used to initialize an
4163    object of type TYPE.  */
4164
4165 void
4166 maybe_warn_string_init (tree type, struct c_expr expr)
4167 {
4168   if (pedantic
4169       && TREE_CODE (type) == ARRAY_TYPE
4170       && TREE_CODE (expr.value) == STRING_CST
4171       && expr.original_code != STRING_CST)
4172     pedwarn_init ("array initialized from parenthesized string constant");
4173 }
4174
4175 /* Digest the parser output INIT as an initializer for type TYPE.
4176    Return a C expression of type TYPE to represent the initial value.
4177
4178    If INIT is a string constant, STRICT_STRING is true if it is
4179    unparenthesized or we should not warn here for it being parenthesized.
4180    For other types of INIT, STRICT_STRING is not used.
4181
4182    REQUIRE_CONSTANT requests an error if non-constant initializers or
4183    elements are seen.  */
4184
4185 static tree
4186 digest_init (tree type, tree init, bool strict_string, int require_constant)
4187 {
4188   enum tree_code code = TREE_CODE (type);
4189   tree inside_init = init;
4190
4191   if (type == error_mark_node
4192       || init == error_mark_node
4193       || TREE_TYPE (init) == error_mark_node)
4194     return error_mark_node;
4195
4196   STRIP_TYPE_NOPS (inside_init);
4197
4198   inside_init = fold (inside_init);
4199
4200   /* Initialization of an array of chars from a string constant
4201      optionally enclosed in braces.  */
4202
4203   if (code == ARRAY_TYPE && inside_init
4204       && TREE_CODE (inside_init) == STRING_CST)
4205     {
4206       tree typ1 = TYPE_MAIN_VARIANT (TREE_TYPE (type));
4207       /* Note that an array could be both an array of character type
4208          and an array of wchar_t if wchar_t is signed char or unsigned
4209          char.  */
4210       bool char_array = (typ1 == char_type_node
4211                          || typ1 == signed_char_type_node
4212                          || typ1 == unsigned_char_type_node);
4213       bool wchar_array = !!comptypes (typ1, wchar_type_node);
4214       if (char_array || wchar_array)
4215         {
4216           struct c_expr expr;
4217           bool char_string;
4218           expr.value = inside_init;
4219           expr.original_code = (strict_string ? STRING_CST : ERROR_MARK);
4220           maybe_warn_string_init (type, expr);
4221
4222           char_string
4223             = (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (inside_init)))
4224                == char_type_node);
4225
4226           if (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4227                          TYPE_MAIN_VARIANT (type)))
4228             return inside_init;
4229
4230           if (!wchar_array && !char_string)
4231             {
4232               error_init ("char-array initialized from wide string");
4233               return error_mark_node;
4234             }
4235           if (char_string && !char_array)
4236             {
4237               error_init ("wchar_t-array initialized from non-wide string");
4238               return error_mark_node;
4239             }
4240
4241           TREE_TYPE (inside_init) = type;
4242           if (TYPE_DOMAIN (type) != 0
4243               && TYPE_SIZE (type) != 0
4244               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
4245               /* Subtract 1 (or sizeof (wchar_t))
4246                  because it's ok to ignore the terminating null char
4247                  that is counted in the length of the constant.  */
4248               && 0 > compare_tree_int (TYPE_SIZE_UNIT (type),
4249                                        TREE_STRING_LENGTH (inside_init)
4250                                        - ((TYPE_PRECISION (typ1)
4251                                            != TYPE_PRECISION (char_type_node))
4252                                           ? (TYPE_PRECISION (wchar_type_node)
4253                                              / BITS_PER_UNIT)
4254                                           : 1)))
4255             pedwarn_init ("initializer-string for array of chars is too long");
4256
4257           return inside_init;
4258         }
4259       else if (INTEGRAL_TYPE_P (typ1))
4260         {
4261           error_init ("array of inappropriate type initialized "
4262                       "from string constant");
4263           return error_mark_node;
4264         }
4265     }
4266
4267   /* Build a VECTOR_CST from a *constant* vector constructor.  If the
4268      vector constructor is not constant (e.g. {1,2,3,foo()}) then punt
4269      below and handle as a constructor.  */
4270   if (code == VECTOR_TYPE
4271       && TREE_CODE (TREE_TYPE (inside_init)) == VECTOR_TYPE
4272       && vector_types_convertible_p (TREE_TYPE (inside_init), type)
4273       && TREE_CONSTANT (inside_init))
4274     {
4275       if (TREE_CODE (inside_init) == VECTOR_CST
4276           && comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4277                         TYPE_MAIN_VARIANT (type)))
4278         return inside_init;
4279
4280       if (TREE_CODE (inside_init) == CONSTRUCTOR)
4281         {
4282           tree link;
4283
4284           /* Iterate through elements and check if all constructor
4285              elements are *_CSTs.  */
4286           for (link = CONSTRUCTOR_ELTS (inside_init);
4287                link;
4288                link = TREE_CHAIN (link))
4289             if (! CONSTANT_CLASS_P (TREE_VALUE (link)))
4290               break;
4291
4292           if (link == NULL)
4293             return build_vector (type, CONSTRUCTOR_ELTS (inside_init));
4294         }
4295     }
4296
4297   /* Any type can be initialized
4298      from an expression of the same type, optionally with braces.  */
4299
4300   if (inside_init && TREE_TYPE (inside_init) != 0
4301       && (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4302                      TYPE_MAIN_VARIANT (type))
4303           || (code == ARRAY_TYPE
4304               && comptypes (TREE_TYPE (inside_init), type))
4305           || (code == VECTOR_TYPE
4306               && comptypes (TREE_TYPE (inside_init), type))
4307           || (code == POINTER_TYPE
4308               && TREE_CODE (TREE_TYPE (inside_init)) == ARRAY_TYPE
4309               && comptypes (TREE_TYPE (TREE_TYPE (inside_init)),
4310                             TREE_TYPE (type)))
4311           || (code == POINTER_TYPE
4312               && TREE_CODE (TREE_TYPE (inside_init)) == FUNCTION_TYPE
4313               && comptypes (TREE_TYPE (inside_init),
4314                             TREE_TYPE (type)))))
4315     {
4316       if (code == POINTER_TYPE)
4317         {
4318           inside_init = default_function_array_conversion (inside_init);
4319
4320           if (TREE_CODE (TREE_TYPE (inside_init)) == ARRAY_TYPE)
4321             {
4322               error_init ("invalid use of non-lvalue array");
4323               return error_mark_node;
4324             }
4325          }
4326
4327       if (code == VECTOR_TYPE)
4328         /* Although the types are compatible, we may require a
4329            conversion.  */
4330         inside_init = convert (type, inside_init);
4331
4332       if (require_constant && !flag_isoc99
4333           && TREE_CODE (inside_init) == COMPOUND_LITERAL_EXPR)
4334         {
4335           /* As an extension, allow initializing objects with static storage
4336              duration with compound literals (which are then treated just as
4337              the brace enclosed list they contain).  */
4338           tree decl = COMPOUND_LITERAL_EXPR_DECL (inside_init);
4339           inside_init = DECL_INITIAL (decl);
4340         }
4341
4342       if (code == ARRAY_TYPE && TREE_CODE (inside_init) != STRING_CST
4343           && TREE_CODE (inside_init) != CONSTRUCTOR)
4344         {
4345           error_init ("array initialized from non-constant array expression");
4346           return error_mark_node;
4347         }
4348
4349       if (optimize && TREE_CODE (inside_init) == VAR_DECL)
4350         inside_init = decl_constant_value_for_broken_optimization (inside_init);
4351
4352       /* Compound expressions can only occur here if -pedantic or
4353          -pedantic-errors is specified.  In the later case, we always want
4354          an error.  In the former case, we simply want a warning.  */
4355       if (require_constant && pedantic
4356           && TREE_CODE (inside_init) == COMPOUND_EXPR)
4357         {
4358           inside_init
4359             = valid_compound_expr_initializer (inside_init,
4360                                                TREE_TYPE (inside_init));
4361           if (inside_init == error_mark_node)
4362             error_init ("initializer element is not constant");
4363           else
4364             pedwarn_init ("initializer element is not constant");
4365           if (flag_pedantic_errors)
4366             inside_init = error_mark_node;
4367         }
4368       else if (require_constant
4369                && !initializer_constant_valid_p (inside_init,
4370                                                  TREE_TYPE (inside_init)))
4371         {
4372           error_init ("initializer element is not constant");
4373           inside_init = error_mark_node;
4374         }
4375
4376       return inside_init;
4377     }
4378
4379   /* Handle scalar types, including conversions.  */
4380
4381   if (code == INTEGER_TYPE || code == REAL_TYPE || code == POINTER_TYPE
4382       || code == ENUMERAL_TYPE || code == BOOLEAN_TYPE || code == COMPLEX_TYPE
4383       || code == VECTOR_TYPE)
4384     {
4385       /* Note that convert_for_assignment calls default_conversion
4386          for arrays and functions.  We must not call it in the
4387          case where inside_init is a null pointer constant.  */
4388       inside_init
4389         = convert_for_assignment (type, init, ic_init,
4390                                   NULL_TREE, NULL_TREE, 0);
4391
4392       /* Check to see if we have already given an error message.  */
4393       if (inside_init == error_mark_node)
4394         ;
4395       else if (require_constant && !TREE_CONSTANT (inside_init))
4396         {
4397           error_init ("initializer element is not constant");
4398           inside_init = error_mark_node;
4399         }
4400       else if (require_constant
4401                && !initializer_constant_valid_p (inside_init,
4402                                                  TREE_TYPE (inside_init)))
4403         {
4404           error_init ("initializer element is not computable at load time");
4405           inside_init = error_mark_node;
4406         }
4407
4408       return inside_init;
4409     }
4410
4411   /* Come here only for records and arrays.  */
4412
4413   if (COMPLETE_TYPE_P (type) && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
4414     {
4415       error_init ("variable-sized object may not be initialized");
4416       return error_mark_node;
4417     }
4418
4419   error_init ("invalid initializer");
4420   return error_mark_node;
4421 }
4422 \f
4423 /* Handle initializers that use braces.  */
4424
4425 /* Type of object we are accumulating a constructor for.
4426    This type is always a RECORD_TYPE, UNION_TYPE or ARRAY_TYPE.  */
4427 static tree constructor_type;
4428
4429 /* For a RECORD_TYPE or UNION_TYPE, this is the chain of fields
4430    left to fill.  */
4431 static tree constructor_fields;
4432
4433 /* For an ARRAY_TYPE, this is the specified index
4434    at which to store the next element we get.  */
4435 static tree constructor_index;
4436
4437 /* For an ARRAY_TYPE, this is the maximum index.  */
4438 static tree constructor_max_index;
4439
4440 /* For a RECORD_TYPE, this is the first field not yet written out.  */
4441 static tree constructor_unfilled_fields;
4442
4443 /* For an ARRAY_TYPE, this is the index of the first element
4444    not yet written out.  */
4445 static tree constructor_unfilled_index;
4446
4447 /* In a RECORD_TYPE, the byte index of the next consecutive field.
4448    This is so we can generate gaps between fields, when appropriate.  */
4449 static tree constructor_bit_index;
4450
4451 /* If we are saving up the elements rather than allocating them,
4452    this is the list of elements so far (in reverse order,
4453    most recent first).  */
4454 static tree constructor_elements;
4455
4456 /* 1 if constructor should be incrementally stored into a constructor chain,
4457    0 if all the elements should be kept in AVL tree.  */
4458 static int constructor_incremental;
4459
4460 /* 1 if so far this constructor's elements are all compile-time constants.  */
4461 static int constructor_constant;
4462
4463 /* 1 if so far this constructor's elements are all valid address constants.  */
4464 static int constructor_simple;
4465
4466 /* 1 if this constructor is erroneous so far.  */
4467 static int constructor_erroneous;
4468
4469 /* Structure for managing pending initializer elements, organized as an
4470    AVL tree.  */
4471
4472 struct init_node
4473 {
4474   struct init_node *left, *right;
4475   struct init_node *parent;
4476   int balance;
4477   tree purpose;
4478   tree value;
4479 };
4480
4481 /* Tree of pending elements at this constructor level.
4482    These are elements encountered out of order
4483    which belong at places we haven't reached yet in actually
4484    writing the output.
4485    Will never hold tree nodes across GC runs.  */
4486 static struct init_node *constructor_pending_elts;
4487
4488 /* The SPELLING_DEPTH of this constructor.  */
4489 static int constructor_depth;
4490
4491 /* DECL node for which an initializer is being read.
4492    0 means we are reading a constructor expression
4493    such as (struct foo) {...}.  */
4494 static tree constructor_decl;
4495
4496 /* Nonzero if this is an initializer for a top-level decl.  */
4497 static int constructor_top_level;
4498
4499 /* Nonzero if there were any member designators in this initializer.  */
4500 static int constructor_designated;
4501
4502 /* Nesting depth of designator list.  */
4503 static int designator_depth;
4504
4505 /* Nonzero if there were diagnosed errors in this designator list.  */
4506 static int designator_errorneous;
4507
4508 \f
4509 /* This stack has a level for each implicit or explicit level of
4510    structuring in the initializer, including the outermost one.  It
4511    saves the values of most of the variables above.  */
4512
4513 struct constructor_range_stack;
4514
4515 struct constructor_stack
4516 {
4517   struct constructor_stack *next;
4518   tree type;
4519   tree fields;
4520   tree index;
4521   tree max_index;
4522   tree unfilled_index;
4523   tree unfilled_fields;
4524   tree bit_index;
4525   tree elements;
4526   struct init_node *pending_elts;
4527   int offset;
4528   int depth;
4529   /* If value nonzero, this value should replace the entire
4530      constructor at this level.  */
4531   struct c_expr replacement_value;
4532   struct constructor_range_stack *range_stack;
4533   char constant;
4534   char simple;
4535   char implicit;
4536   char erroneous;
4537   char outer;
4538   char incremental;
4539   char designated;
4540 };
4541
4542 static struct constructor_stack *constructor_stack;
4543
4544 /* This stack represents designators from some range designator up to
4545    the last designator in the list.  */
4546
4547 struct constructor_range_stack
4548 {
4549   struct constructor_range_stack *next, *prev;
4550   struct constructor_stack *stack;
4551   tree range_start;
4552   tree index;
4553   tree range_end;
4554   tree fields;
4555 };
4556
4557 static struct constructor_range_stack *constructor_range_stack;
4558
4559 /* This stack records separate initializers that are nested.
4560    Nested initializers can't happen in ANSI C, but GNU C allows them
4561    in cases like { ... (struct foo) { ... } ... }.  */
4562
4563 struct initializer_stack
4564 {
4565   struct initializer_stack *next;
4566   tree decl;
4567   struct constructor_stack *constructor_stack;
4568   struct constructor_range_stack *constructor_range_stack;
4569   tree elements;
4570   struct spelling *spelling;
4571   struct spelling *spelling_base;
4572   int spelling_size;
4573   char top_level;
4574   char require_constant_value;
4575   char require_constant_elements;
4576 };
4577
4578 static struct initializer_stack *initializer_stack;
4579 \f
4580 /* Prepare to parse and output the initializer for variable DECL.  */
4581
4582 void
4583 start_init (tree decl, tree asmspec_tree ATTRIBUTE_UNUSED, int top_level)
4584 {
4585   const char *locus;
4586   struct initializer_stack *p = xmalloc (sizeof (struct initializer_stack));
4587
4588   p->decl = constructor_decl;
4589   p->require_constant_value = require_constant_value;
4590   p->require_constant_elements = require_constant_elements;
4591   p->constructor_stack = constructor_stack;
4592   p->constructor_range_stack = constructor_range_stack;
4593   p->elements = constructor_elements;
4594   p->spelling = spelling;
4595   p->spelling_base = spelling_base;
4596   p->spelling_size = spelling_size;
4597   p->top_level = constructor_top_level;
4598   p->next = initializer_stack;
4599   initializer_stack = p;
4600
4601   constructor_decl = decl;
4602   constructor_designated = 0;
4603   constructor_top_level = top_level;
4604
4605   if (decl != 0 && decl != error_mark_node)
4606     {
4607       require_constant_value = TREE_STATIC (decl);
4608       require_constant_elements
4609         = ((TREE_STATIC (decl) || (pedantic && !flag_isoc99))
4610            /* For a scalar, you can always use any value to initialize,
4611               even within braces.  */
4612            && (TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE
4613                || TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
4614                || TREE_CODE (TREE_TYPE (decl)) == UNION_TYPE
4615                || TREE_CODE (TREE_TYPE (decl)) == QUAL_UNION_TYPE));
4616       locus = IDENTIFIER_POINTER (DECL_NAME (decl));
4617     }
4618   else
4619     {
4620       require_constant_value = 0;
4621       require_constant_elements = 0;
4622       locus = "(anonymous)";
4623     }
4624
4625   constructor_stack = 0;
4626   constructor_range_stack = 0;
4627
4628   missing_braces_mentioned = 0;
4629
4630   spelling_base = 0;
4631   spelling_size = 0;
4632   RESTORE_SPELLING_DEPTH (0);
4633
4634   if (locus)
4635     push_string (locus);
4636 }
4637
4638 void
4639 finish_init (void)
4640 {
4641   struct initializer_stack *p = initializer_stack;
4642
4643   /* Free the whole constructor stack of this initializer.  */
4644   while (constructor_stack)
4645     {
4646       struct constructor_stack *q = constructor_stack;
4647       constructor_stack = q->next;
4648       free (q);
4649     }
4650
4651   gcc_assert (!constructor_range_stack);
4652
4653   /* Pop back to the data of the outer initializer (if any).  */
4654   free (spelling_base);
4655
4656   constructor_decl = p->decl;
4657   require_constant_value = p->require_constant_value;
4658   require_constant_elements = p->require_constant_elements;
4659   constructor_stack = p->constructor_stack;
4660   constructor_range_stack = p->constructor_range_stack;
4661   constructor_elements = p->elements;
4662   spelling = p->spelling;
4663   spelling_base = p->spelling_base;
4664   spelling_size = p->spelling_size;
4665   constructor_top_level = p->top_level;
4666   initializer_stack = p->next;
4667   free (p);
4668 }
4669 \f
4670 /* Call here when we see the initializer is surrounded by braces.
4671    This is instead of a call to push_init_level;
4672    it is matched by a call to pop_init_level.
4673
4674    TYPE is the type to initialize, for a constructor expression.
4675    For an initializer for a decl, TYPE is zero.  */
4676
4677 void
4678 really_start_incremental_init (tree type)
4679 {
4680   struct constructor_stack *p = XNEW (struct constructor_stack);
4681
4682   if (type == 0)
4683     type = TREE_TYPE (constructor_decl);
4684
4685   if (targetm.vector_opaque_p (type))
4686     error ("opaque vector types cannot be initialized");
4687
4688   p->type = constructor_type;
4689   p->fields = constructor_fields;
4690   p->index = constructor_index;
4691   p->max_index = constructor_max_index;
4692   p->unfilled_index = constructor_unfilled_index;
4693   p->unfilled_fields = constructor_unfilled_fields;
4694   p->bit_index = constructor_bit_index;
4695   p->elements = constructor_elements;
4696   p->constant = constructor_constant;
4697   p->simple = constructor_simple;
4698   p->erroneous = constructor_erroneous;
4699   p->pending_elts = constructor_pending_elts;
4700   p->depth = constructor_depth;
4701   p->replacement_value.value = 0;
4702   p->replacement_value.original_code = ERROR_MARK;
4703   p->implicit = 0;
4704   p->range_stack = 0;
4705   p->outer = 0;
4706   p->incremental = constructor_incremental;
4707   p->designated = constructor_designated;
4708   p->next = 0;
4709   constructor_stack = p;
4710
4711   constructor_constant = 1;
4712   constructor_simple = 1;
4713   constructor_depth = SPELLING_DEPTH ();
4714   constructor_elements = 0;
4715   constructor_pending_elts = 0;
4716   constructor_type = type;
4717   constructor_incremental = 1;
4718   constructor_designated = 0;
4719   designator_depth = 0;
4720   designator_errorneous = 0;
4721
4722   if (TREE_CODE (constructor_type) == RECORD_TYPE
4723       || TREE_CODE (constructor_type) == UNION_TYPE)
4724     {
4725       constructor_fields = TYPE_FIELDS (constructor_type);
4726       /* Skip any nameless bit fields at the beginning.  */
4727       while (constructor_fields != 0 && DECL_C_BIT_FIELD (constructor_fields)
4728              && DECL_NAME (constructor_fields) == 0)
4729         constructor_fields = TREE_CHAIN (constructor_fields);
4730
4731       constructor_unfilled_fields = constructor_fields;
4732       constructor_bit_index = bitsize_zero_node;
4733     }
4734   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
4735     {
4736       if (TYPE_DOMAIN (constructor_type))
4737         {
4738           constructor_max_index
4739             = TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type));
4740
4741           /* Detect non-empty initializations of zero-length arrays.  */
4742           if (constructor_max_index == NULL_TREE
4743               && TYPE_SIZE (constructor_type))
4744             constructor_max_index = build_int_cst (NULL_TREE, -1);
4745
4746           /* constructor_max_index needs to be an INTEGER_CST.  Attempts
4747              to initialize VLAs will cause a proper error; avoid tree
4748              checking errors as well by setting a safe value.  */
4749           if (constructor_max_index
4750               && TREE_CODE (constructor_max_index) != INTEGER_CST)
4751             constructor_max_index = build_int_cst (NULL_TREE, -1);
4752
4753           constructor_index
4754             = convert (bitsizetype,
4755                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
4756         }
4757       else
4758         {
4759           constructor_index = bitsize_zero_node;
4760           constructor_max_index = NULL_TREE;
4761         }
4762
4763       constructor_unfilled_index = constructor_index;
4764     }
4765   else if (TREE_CODE (constructor_type) == VECTOR_TYPE)
4766     {
4767       /* Vectors are like simple fixed-size arrays.  */
4768       constructor_max_index =
4769         build_int_cst (NULL_TREE, TYPE_VECTOR_SUBPARTS (constructor_type) - 1);
4770       constructor_index = convert (bitsizetype, bitsize_zero_node);
4771       constructor_unfilled_index = constructor_index;
4772     }
4773   else
4774     {
4775       /* Handle the case of int x = {5}; */
4776       constructor_fields = constructor_type;
4777       constructor_unfilled_fields = constructor_type;
4778     }
4779 }
4780 \f
4781 /* Push down into a subobject, for initialization.
4782    If this is for an explicit set of braces, IMPLICIT is 0.
4783    If it is because the next element belongs at a lower level,
4784    IMPLICIT is 1 (or 2 if the push is because of designator list).  */
4785
4786 void
4787 push_init_level (int implicit)
4788 {
4789   struct constructor_stack *p;
4790   tree value = NULL_TREE;
4791
4792   /* If we've exhausted any levels that didn't have braces,
4793      pop them now.  */
4794   while (constructor_stack->implicit)
4795     {
4796       if ((TREE_CODE (constructor_type) == RECORD_TYPE
4797            || TREE_CODE (constructor_type) == UNION_TYPE)
4798           && constructor_fields == 0)
4799         process_init_element (pop_init_level (1));
4800       else if (TREE_CODE (constructor_type) == ARRAY_TYPE
4801                && constructor_max_index
4802                && tree_int_cst_lt (constructor_max_index, constructor_index))
4803         process_init_element (pop_init_level (1));
4804       else
4805         break;
4806     }
4807
4808   /* Unless this is an explicit brace, we need to preserve previous
4809      content if any.  */
4810   if (implicit)
4811     {
4812       if ((TREE_CODE (constructor_type) == RECORD_TYPE
4813            || TREE_CODE (constructor_type) == UNION_TYPE)
4814           && constructor_fields)
4815         value = find_init_member (constructor_fields);
4816       else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
4817         value = find_init_member (constructor_index);
4818     }
4819
4820   p = XNEW (struct constructor_stack);
4821   p->type = constructor_type;
4822   p->fields = constructor_fields;
4823   p->index = constructor_index;
4824   p->max_index = constructor_max_index;
4825   p->unfilled_index = constructor_unfilled_index;
4826   p->unfilled_fields = constructor_unfilled_fields;
4827   p->bit_index = constructor_bit_index;
4828   p->elements = constructor_elements;
4829   p->constant = constructor_constant;
4830   p->simple = constructor_simple;
4831   p->erroneous = constructor_erroneous;
4832   p->pending_elts = constructor_pending_elts;
4833   p->depth = constructor_depth;
4834   p->replacement_value.value = 0;
4835   p->replacement_value.original_code = ERROR_MARK;
4836   p->implicit = implicit;
4837   p->outer = 0;
4838   p->incremental = constructor_incremental;
4839   p->designated = constructor_designated;
4840   p->next = constructor_stack;
4841   p->range_stack = 0;
4842   constructor_stack = p;
4843
4844   constructor_constant = 1;
4845   constructor_simple = 1;
4846   constructor_depth = SPELLING_DEPTH ();
4847   constructor_elements = 0;
4848   constructor_incremental = 1;
4849   constructor_designated = 0;
4850   constructor_pending_elts = 0;
4851   if (!implicit)
4852     {
4853       p->range_stack = constructor_range_stack;
4854       constructor_range_stack = 0;
4855       designator_depth = 0;
4856       designator_errorneous = 0;
4857     }
4858
4859   /* Don't die if an entire brace-pair level is superfluous
4860      in the containing level.  */
4861   if (constructor_type == 0)
4862     ;
4863   else if (TREE_CODE (constructor_type) == RECORD_TYPE
4864            || TREE_CODE (constructor_type) == UNION_TYPE)
4865     {
4866       /* Don't die if there are extra init elts at the end.  */
4867       if (constructor_fields == 0)
4868         constructor_type = 0;
4869       else
4870         {
4871           constructor_type = TREE_TYPE (constructor_fields);
4872           push_member_name (constructor_fields);
4873           constructor_depth++;
4874         }
4875     }
4876   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
4877     {
4878       constructor_type = TREE_TYPE (constructor_type);
4879       push_array_bounds (tree_low_cst (constructor_index, 0));
4880       constructor_depth++;
4881     }
4882
4883   if (constructor_type == 0)
4884     {
4885       error_init ("extra brace group at end of initializer");
4886       constructor_fields = 0;
4887       constructor_unfilled_fields = 0;
4888       return;
4889     }
4890
4891   if (value && TREE_CODE (value) == CONSTRUCTOR)
4892     {
4893       constructor_constant = TREE_CONSTANT (value);
4894       constructor_simple = TREE_STATIC (value);
4895       constructor_elements = CONSTRUCTOR_ELTS (value);
4896       if (constructor_elements
4897           && (TREE_CODE (constructor_type) == RECORD_TYPE
4898               || TREE_CODE (constructor_type) == ARRAY_TYPE))
4899         set_nonincremental_init ();
4900     }
4901
4902   if (implicit == 1 && warn_missing_braces && !missing_braces_mentioned)
4903     {
4904       missing_braces_mentioned = 1;
4905       warning_init ("missing braces around initializer");
4906     }
4907
4908   if (TREE_CODE (constructor_type) == RECORD_TYPE
4909            || TREE_CODE (constructor_type) == UNION_TYPE)
4910     {
4911       constructor_fields = TYPE_FIELDS (constructor_type);
4912       /* Skip any nameless bit fields at the beginning.  */
4913       while (constructor_fields != 0 && DECL_C_BIT_FIELD (constructor_fields)
4914              && DECL_NAME (constructor_fields) == 0)
4915         constructor_fields = TREE_CHAIN (constructor_fields);
4916
4917       constructor_unfilled_fields = constructor_fields;
4918       constructor_bit_index = bitsize_zero_node;
4919     }
4920   else if (TREE_CODE (constructor_type) == VECTOR_TYPE)
4921     {
4922       /* Vectors are like simple fixed-size arrays.  */
4923       constructor_max_index =
4924         build_int_cst (NULL_TREE, TYPE_VECTOR_SUBPARTS (constructor_type) - 1);
4925       constructor_index = convert (bitsizetype, integer_zero_node);
4926       constructor_unfilled_index = constructor_index;
4927     }
4928   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
4929     {
4930       if (TYPE_DOMAIN (constructor_type))
4931         {
4932           constructor_max_index
4933             = TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type));
4934
4935           /* Detect non-empty initializations of zero-length arrays.  */
4936           if (constructor_max_index == NULL_TREE
4937               && TYPE_SIZE (constructor_type))
4938             constructor_max_index = build_int_cst (NULL_TREE, -1);
4939
4940           /* constructor_max_index needs to be an INTEGER_CST.  Attempts
4941              to initialize VLAs will cause a proper error; avoid tree
4942              checking errors as well by setting a safe value.  */
4943           if (constructor_max_index
4944               && TREE_CODE (constructor_max_index) != INTEGER_CST)
4945             constructor_max_index = build_int_cst (NULL_TREE, -1);
4946
4947           constructor_index
4948             = convert (bitsizetype,
4949                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
4950         }
4951       else
4952         constructor_index = bitsize_zero_node;
4953
4954       constructor_unfilled_index = constructor_index;
4955       if (value && TREE_CODE (value) == STRING_CST)
4956         {
4957           /* We need to split the char/wchar array into individual
4958              characters, so that we don't have to special case it
4959              everywhere.  */
4960           set_nonincremental_init_from_string (value);
4961         }
4962     }
4963   else
4964     {
4965       if (constructor_type != error_mark_node)
4966         warning_init ("braces around scalar initializer");
4967       constructor_fields = constructor_type;
4968       constructor_unfilled_fields = constructor_type;
4969     }
4970 }
4971
4972 /* At the end of an implicit or explicit brace level,
4973    finish up that level of constructor.  If a single expression
4974    with redundant braces initialized that level, return the
4975    c_expr structure for that expression.  Otherwise, the original_code
4976    element is set to ERROR_MARK.
4977    If we were outputting the elements as they are read, return 0 as the value
4978    from inner levels (process_init_element ignores that),
4979    but return error_mark_node as the value from the outermost level
4980    (that's what we want to put in DECL_INITIAL).
4981    Otherwise, return a CONSTRUCTOR expression as the value.  */
4982
4983 struct c_expr
4984 pop_init_level (int implicit)
4985 {
4986   struct constructor_stack *p;
4987   struct c_expr ret;
4988   ret.value = 0;
4989   ret.original_code = ERROR_MARK;
4990
4991   if (implicit == 0)
4992     {
4993       /* When we come to an explicit close brace,
4994          pop any inner levels that didn't have explicit braces.  */
4995       while (constructor_stack->implicit)
4996         process_init_element (pop_init_level (1));
4997
4998       gcc_assert (!constructor_range_stack);
4999     }
5000
5001   /* Now output all pending elements.  */
5002   constructor_incremental = 1;
5003   output_pending_init_elements (1);
5004
5005   p = constructor_stack;
5006
5007   /* Error for initializing a flexible array member, or a zero-length
5008      array member in an inappropriate context.  */
5009   if (constructor_type && constructor_fields
5010       && TREE_CODE (constructor_type) == ARRAY_TYPE
5011       && TYPE_DOMAIN (constructor_type)
5012       && !TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type)))
5013     {
5014       /* Silently discard empty initializations.  The parser will
5015          already have pedwarned for empty brackets.  */
5016       if (integer_zerop (constructor_unfilled_index))
5017         constructor_type = NULL_TREE;
5018       else
5019         {
5020           gcc_assert (!TYPE_SIZE (constructor_type));
5021
5022           if (constructor_depth > 2)
5023             error_init ("initialization of flexible array member in a nested context");
5024           else if (pedantic)
5025             pedwarn_init ("initialization of a flexible array member");
5026
5027           /* We have already issued an error message for the existence
5028              of a flexible array member not at the end of the structure.
5029              Discard the initializer so that we do not die later.  */
5030           if (TREE_CHAIN (constructor_fields) != NULL_TREE)
5031             constructor_type = NULL_TREE;
5032         }
5033     }
5034
5035   /* Warn when some struct elements are implicitly initialized to zero.  */
5036   if (warn_missing_field_initializers
5037       && constructor_type
5038       && TREE_CODE (constructor_type) == RECORD_TYPE
5039       && constructor_unfilled_fields)
5040     {
5041         /* Do not warn for flexible array members or zero-length arrays.  */
5042         while (constructor_unfilled_fields
5043                && (!DECL_SIZE (constructor_unfilled_fields)
5044                    || integer_zerop (DECL_SIZE (constructor_unfilled_fields))))
5045           constructor_unfilled_fields = TREE_CHAIN (constructor_unfilled_fields);
5046
5047         /* Do not warn if this level of the initializer uses member
5048            designators; it is likely to be deliberate.  */
5049         if (constructor_unfilled_fields && !constructor_designated)
5050           {
5051             push_member_name (constructor_unfilled_fields);
5052             warning_init ("missing initializer");
5053             RESTORE_SPELLING_DEPTH (constructor_depth);
5054           }
5055     }
5056
5057   /* Pad out the end of the structure.  */
5058   if (p->replacement_value.value)
5059     /* If this closes a superfluous brace pair,
5060        just pass out the element between them.  */
5061     ret = p->replacement_value;
5062   else if (constructor_type == 0)
5063     ;
5064   else if (TREE_CODE (constructor_type) != RECORD_TYPE
5065            && TREE_CODE (constructor_type) != UNION_TYPE
5066            && TREE_CODE (constructor_type) != ARRAY_TYPE
5067            && TREE_CODE (constructor_type) != VECTOR_TYPE)
5068     {
5069       /* A nonincremental scalar initializer--just return
5070          the element, after verifying there is just one.  */
5071       if (constructor_elements == 0)
5072         {
5073           if (!constructor_erroneous)
5074             error_init ("empty scalar initializer");
5075           ret.value = error_mark_node;
5076         }
5077       else if (TREE_CHAIN (constructor_elements) != 0)
5078         {
5079           error_init ("extra elements in scalar initializer");
5080           ret.value = TREE_VALUE (constructor_elements);
5081         }
5082       else
5083         ret.value = TREE_VALUE (constructor_elements);
5084     }
5085   else
5086     {
5087       if (constructor_erroneous)
5088         ret.value = error_mark_node;
5089       else
5090         {
5091           ret.value = build_constructor (constructor_type,
5092                                          nreverse (constructor_elements));
5093           if (constructor_constant)
5094             TREE_CONSTANT (ret.value) = TREE_INVARIANT (ret.value) = 1;
5095           if (constructor_constant && constructor_simple)
5096             TREE_STATIC (ret.value) = 1;
5097         }
5098     }
5099
5100   constructor_type = p->type;
5101   constructor_fields = p->fields;
5102   constructor_index = p->index;
5103   constructor_max_index = p->max_index;
5104   constructor_unfilled_index = p->unfilled_index;
5105   constructor_unfilled_fields = p->unfilled_fields;
5106   constructor_bit_index = p->bit_index;
5107   constructor_elements = p->elements;
5108   constructor_constant = p->constant;
5109   constructor_simple = p->simple;
5110   constructor_erroneous = p->erroneous;
5111   constructor_incremental = p->incremental;
5112   constructor_designated = p->designated;
5113   constructor_pending_elts = p->pending_elts;
5114   constructor_depth = p->depth;
5115   if (!p->implicit)
5116     constructor_range_stack = p->range_stack;
5117   RESTORE_SPELLING_DEPTH (constructor_depth);
5118
5119   constructor_stack = p->next;
5120   free (p);
5121
5122   if (ret.value == 0)
5123     {
5124       if (constructor_stack == 0)
5125         {
5126           ret.value = error_mark_node;
5127           return ret;
5128         }
5129       return ret;
5130     }
5131   return ret;
5132 }
5133
5134 /* Common handling for both array range and field name designators.
5135    ARRAY argument is nonzero for array ranges.  Returns zero for success.  */
5136
5137 static int
5138 set_designator (int array)
5139 {
5140   tree subtype;
5141   enum tree_code subcode;
5142
5143   /* Don't die if an entire brace-pair level is superfluous
5144      in the containing level.  */
5145   if (constructor_type == 0)
5146     return 1;
5147
5148   /* If there were errors in this designator list already, bail out
5149      silently.  */
5150   if (designator_errorneous)
5151     return 1;
5152
5153   if (!designator_depth)
5154     {
5155       gcc_assert (!constructor_range_stack);
5156
5157       /* Designator list starts at the level of closest explicit
5158          braces.  */
5159       while (constructor_stack->implicit)
5160         process_init_element (pop_init_level (1));
5161       constructor_designated = 1;
5162       return 0;
5163     }
5164
5165   switch (TREE_CODE (constructor_type))
5166     {
5167     case  RECORD_TYPE:
5168     case  UNION_TYPE:
5169       subtype = TREE_TYPE (constructor_fields);
5170       if (subtype != error_mark_node)
5171         subtype = TYPE_MAIN_VARIANT (subtype);
5172       break;
5173     case ARRAY_TYPE:
5174       subtype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
5175       break;
5176     default:
5177       gcc_unreachable ();
5178     }
5179
5180   subcode = TREE_CODE (subtype);
5181   if (array && subcode != ARRAY_TYPE)
5182     {
5183       error_init ("array index in non-array initializer");
5184       return 1;
5185     }
5186   else if (!array && subcode != RECORD_TYPE && subcode != UNION_TYPE)
5187     {
5188       error_init ("field name not in record or union initializer");
5189       return 1;
5190     }
5191
5192   constructor_designated = 1;
5193   push_init_level (2);
5194   return 0;
5195 }
5196
5197 /* If there are range designators in designator list, push a new designator
5198    to constructor_range_stack.  RANGE_END is end of such stack range or
5199    NULL_TREE if there is no range designator at this level.  */
5200
5201 static void
5202 push_range_stack (tree range_end)
5203 {
5204   struct constructor_range_stack *p;
5205
5206   p = GGC_NEW (struct constructor_range_stack);
5207   p->prev = constructor_range_stack;
5208   p->next = 0;
5209   p->fields = constructor_fields;
5210   p->range_start = constructor_index;
5211   p->index = constructor_index;
5212   p->stack = constructor_stack;
5213   p->range_end = range_end;
5214   if (constructor_range_stack)
5215     constructor_range_stack->next = p;
5216   constructor_range_stack = p;
5217 }
5218
5219 /* Within an array initializer, specify the next index to be initialized.
5220    FIRST is that index.  If LAST is nonzero, then initialize a range
5221    of indices, running from FIRST through LAST.  */
5222
5223 void
5224 set_init_index (tree first, tree last)
5225 {
5226   if (set_designator (1))
5227     return;
5228
5229   designator_errorneous = 1;
5230
5231   if (!INTEGRAL_TYPE_P (TREE_TYPE (first))
5232       || (last && !INTEGRAL_TYPE_P (TREE_TYPE (last))))
5233     {
5234       error_init ("array index in initializer not of integer type");
5235       return;
5236     }
5237
5238   if (TREE_CODE (first) != INTEGER_CST)
5239     error_init ("nonconstant array index in initializer");
5240   else if (last != 0 && TREE_CODE (last) != INTEGER_CST)
5241     error_init ("nonconstant array index in initializer");
5242   else if (TREE_CODE (constructor_type) != ARRAY_TYPE)
5243     error_init ("array index in non-array initializer");
5244   else if (tree_int_cst_sgn (first) == -1)
5245     error_init ("array index in initializer exceeds array bounds");
5246   else if (constructor_max_index
5247            && tree_int_cst_lt (constructor_max_index, first))
5248     error_init ("array index in initializer exceeds array bounds");
5249   else
5250     {
5251       constructor_index = convert (bitsizetype, first);
5252
5253       if (last)
5254         {
5255           if (tree_int_cst_equal (first, last))
5256             last = 0;
5257           else if (tree_int_cst_lt (last, first))
5258             {
5259               error_init ("empty index range in initializer");
5260               last = 0;
5261             }
5262           else
5263             {
5264               last = convert (bitsizetype, last);
5265               if (constructor_max_index != 0
5266                   && tree_int_cst_lt (constructor_max_index, last))
5267                 {
5268                   error_init ("array index range in initializer exceeds array bounds");
5269                   last = 0;
5270                 }
5271             }
5272         }
5273
5274       designator_depth++;
5275       designator_errorneous = 0;
5276       if (constructor_range_stack || last)
5277         push_range_stack (last);
5278     }
5279 }
5280
5281 /* Within a struct initializer, specify the next field to be initialized.  */
5282
5283 void
5284 set_init_label (tree fieldname)
5285 {
5286   tree tail;
5287
5288   if (set_designator (0))
5289     return;
5290
5291   designator_errorneous = 1;
5292
5293   if (TREE_CODE (constructor_type) != RECORD_TYPE
5294       && TREE_CODE (constructor_type) != UNION_TYPE)
5295     {
5296       error_init ("field name not in record or union initializer");
5297       return;
5298     }
5299
5300   for (tail = TYPE_FIELDS (constructor_type); tail;
5301        tail = TREE_CHAIN (tail))
5302     {
5303       if (DECL_NAME (tail) == fieldname)
5304         break;
5305     }
5306
5307   if (tail == 0)
5308     error ("unknown field %qE specified in initializer", fieldname);
5309   else
5310     {
5311       constructor_fields = tail;
5312       designator_depth++;
5313       designator_errorneous = 0;
5314       if (constructor_range_stack)
5315         push_range_stack (NULL_TREE);
5316     }
5317 }
5318 \f
5319 /* Add a new initializer to the tree of pending initializers.  PURPOSE
5320    identifies the initializer, either array index or field in a structure.
5321    VALUE is the value of that index or field.  */
5322
5323 static void
5324 add_pending_init (tree purpose, tree value)
5325 {
5326   struct init_node *p, **q, *r;
5327
5328   q = &constructor_pending_elts;
5329   p = 0;
5330
5331   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5332     {
5333       while (*q != 0)
5334         {
5335           p = *q;
5336           if (tree_int_cst_lt (purpose, p->purpose))
5337             q = &p->left;
5338           else if (tree_int_cst_lt (p->purpose, purpose))
5339             q = &p->right;
5340           else
5341             {
5342               if (TREE_SIDE_EFFECTS (p->value))
5343                 warning_init ("initialized field with side-effects overwritten");
5344               p->value = value;
5345               return;
5346             }
5347         }
5348     }
5349   else
5350     {
5351       tree bitpos;
5352
5353       bitpos = bit_position (purpose);
5354       while (*q != NULL)
5355         {
5356           p = *q;
5357           if (tree_int_cst_lt (bitpos, bit_position (p->purpose)))
5358             q = &p->left;
5359           else if (p->purpose != purpose)
5360             q = &p->right;
5361           else
5362             {
5363               if (TREE_SIDE_EFFECTS (p->value))
5364                 warning_init ("initialized field with side-effects overwritten");
5365               p->value = value;
5366               return;
5367             }
5368         }
5369     }
5370
5371   r = GGC_NEW (struct init_node);
5372   r->purpose = purpose;
5373   r->value = value;
5374
5375   *q = r;
5376   r->parent = p;
5377   r->left = 0;
5378   r->right = 0;
5379   r->balance = 0;
5380
5381   while (p)
5382     {
5383       struct init_node *s;
5384
5385       if (r == p->left)
5386         {
5387           if (p->balance == 0)
5388             p->balance = -1;
5389           else if (p->balance < 0)
5390             {
5391               if (r->balance < 0)
5392                 {
5393                   /* L rotation.  */
5394                   p->left = r->right;
5395                   if (p->left)
5396                     p->left->parent = p;
5397                   r->right = p;
5398
5399                   p->balance = 0;
5400                   r->balance = 0;
5401
5402                   s = p->parent;
5403                   p->parent = r;
5404                   r->parent = s;
5405                   if (s)
5406                     {
5407                       if (s->left == p)
5408                         s->left = r;
5409                       else
5410                         s->right = r;
5411                     }
5412                   else
5413                     constructor_pending_elts = r;
5414                 }
5415               else
5416                 {
5417                   /* LR rotation.  */
5418                   struct init_node *t = r->right;
5419
5420                   r->right = t->left;
5421                   if (r->right)
5422                     r->right->parent = r;
5423                   t->left = r;
5424
5425                   p->left = t->right;
5426                   if (p->left)
5427                     p->left->parent = p;
5428                   t->right = p;
5429
5430                   p->balance = t->balance < 0;
5431                   r->balance = -(t->balance > 0);
5432                   t->balance = 0;
5433
5434                   s = p->parent;
5435                   p->parent = t;
5436                   r->parent = t;
5437                   t->parent = s;
5438                   if (s)
5439                     {
5440                       if (s->left == p)
5441                         s->left = t;
5442                       else
5443                         s->right = t;
5444                     }
5445                   else
5446                     constructor_pending_elts = t;
5447                 }
5448               break;
5449             }
5450           else
5451             {
5452               /* p->balance == +1; growth of left side balances the node.  */
5453               p->balance = 0;
5454               break;
5455             }
5456         }
5457       else /* r == p->right */
5458         {
5459           if (p->balance == 0)
5460             /* Growth propagation from right side.  */
5461             p->balance++;
5462           else if (p->balance > 0)
5463             {
5464               if (r->balance > 0)
5465                 {
5466                   /* R rotation.  */
5467                   p->right = r->left;
5468                   if (p->right)
5469                     p->right->parent = p;
5470                   r->left = p;
5471
5472                   p->balance = 0;
5473                   r->balance = 0;
5474
5475                   s = p->parent;
5476                   p->parent = r;
5477                   r->parent = s;
5478                   if (s)
5479                     {
5480                       if (s->left == p)
5481                         s->left = r;
5482                       else
5483                         s->right = r;
5484                     }
5485                   else
5486                     constructor_pending_elts = r;
5487                 }
5488               else /* r->balance == -1 */
5489                 {
5490                   /* RL rotation */
5491                   struct init_node *t = r->left;
5492
5493                   r->left = t->right;
5494                   if (r->left)
5495                     r->left->parent = r;
5496                   t->right = r;
5497
5498                   p->right = t->left;
5499                   if (p->right)
5500                     p->right->parent = p;
5501                   t->left = p;
5502
5503                   r->balance = (t->balance < 0);
5504                   p->balance = -(t->balance > 0);
5505                   t->balance = 0;
5506
5507                   s = p->parent;
5508                   p->parent = t;
5509                   r->parent = t;
5510                   t->parent = s;
5511                   if (s)
5512                     {
5513                       if (s->left == p)
5514                         s->left = t;
5515                       else
5516                         s->right = t;
5517                     }
5518                   else
5519                     constructor_pending_elts = t;
5520                 }
5521               break;
5522             }
5523           else
5524             {
5525               /* p->balance == -1; growth of right side balances the node.  */
5526               p->balance = 0;
5527               break;
5528             }
5529         }
5530
5531       r = p;
5532       p = p->parent;
5533     }
5534 }
5535
5536 /* Build AVL tree from a sorted chain.  */
5537
5538 static void
5539 set_nonincremental_init (void)
5540 {
5541   tree chain;
5542
5543   if (TREE_CODE (constructor_type) != RECORD_TYPE
5544       && TREE_CODE (constructor_type) != ARRAY_TYPE)
5545     return;
5546
5547   for (chain = constructor_elements; chain; chain = TREE_CHAIN (chain))
5548     add_pending_init (TREE_PURPOSE (chain), TREE_VALUE (chain));
5549   constructor_elements = 0;
5550   if (TREE_CODE (constructor_type) == RECORD_TYPE)
5551     {
5552       constructor_unfilled_fields = TYPE_FIELDS (constructor_type);
5553       /* Skip any nameless bit fields at the beginning.  */
5554       while (constructor_unfilled_fields != 0
5555              && DECL_C_BIT_FIELD (constructor_unfilled_fields)
5556              && DECL_NAME (constructor_unfilled_fields) == 0)
5557         constructor_unfilled_fields = TREE_CHAIN (constructor_unfilled_fields);
5558
5559     }
5560   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5561     {
5562       if (TYPE_DOMAIN (constructor_type))
5563         constructor_unfilled_index
5564             = convert (bitsizetype,
5565                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
5566       else
5567         constructor_unfilled_index = bitsize_zero_node;
5568     }
5569   constructor_incremental = 0;
5570 }
5571
5572 /* Build AVL tree from a string constant.  */
5573
5574 static void
5575 set_nonincremental_init_from_string (tree str)
5576 {
5577   tree value, purpose, type;
5578   HOST_WIDE_INT val[2];
5579   const char *p, *end;
5580   int byte, wchar_bytes, charwidth, bitpos;
5581
5582   gcc_assert (TREE_CODE (constructor_type) == ARRAY_TYPE);
5583
5584   if (TYPE_PRECISION (TREE_TYPE (TREE_TYPE (str)))
5585       == TYPE_PRECISION (char_type_node))
5586     wchar_bytes = 1;
5587   else
5588     {
5589       gcc_assert (TYPE_PRECISION (TREE_TYPE (TREE_TYPE (str)))
5590                   == TYPE_PRECISION (wchar_type_node));
5591       wchar_bytes = TYPE_PRECISION (wchar_type_node) / BITS_PER_UNIT;
5592     }
5593   charwidth = TYPE_PRECISION (char_type_node);
5594   type = TREE_TYPE (constructor_type);
5595   p = TREE_STRING_POINTER (str);
5596   end = p + TREE_STRING_LENGTH (str);
5597
5598   for (purpose = bitsize_zero_node;
5599        p < end && !tree_int_cst_lt (constructor_max_index, purpose);
5600        purpose = size_binop (PLUS_EXPR, purpose, bitsize_one_node))
5601     {
5602       if (wchar_bytes == 1)
5603         {
5604           val[1] = (unsigned char) *p++;
5605           val[0] = 0;
5606         }
5607       else
5608         {
5609           val[0] = 0;
5610           val[1] = 0;
5611           for (byte = 0; byte < wchar_bytes; byte++)
5612             {
5613               if (BYTES_BIG_ENDIAN)
5614                 bitpos = (wchar_bytes - byte - 1) * charwidth;
5615               else
5616                 bitpos = byte * charwidth;
5617               val[bitpos < HOST_BITS_PER_WIDE_INT]
5618                 |= ((unsigned HOST_WIDE_INT) ((unsigned char) *p++))
5619                    << (bitpos % HOST_BITS_PER_WIDE_INT);
5620             }
5621         }
5622
5623       if (!TYPE_UNSIGNED (type))
5624         {
5625           bitpos = ((wchar_bytes - 1) * charwidth) + HOST_BITS_PER_CHAR;
5626           if (bitpos < HOST_BITS_PER_WIDE_INT)
5627             {
5628               if (val[1] & (((HOST_WIDE_INT) 1) << (bitpos - 1)))
5629                 {
5630                   val[1] |= ((HOST_WIDE_INT) -1) << bitpos;
5631                   val[0] = -1;
5632                 }
5633             }
5634           else if (bitpos == HOST_BITS_PER_WIDE_INT)
5635             {
5636               if (val[1] < 0)
5637                 val[0] = -1;
5638             }
5639           else if (val[0] & (((HOST_WIDE_INT) 1)
5640                              << (bitpos - 1 - HOST_BITS_PER_WIDE_INT)))
5641             val[0] |= ((HOST_WIDE_INT) -1)
5642                       << (bitpos - HOST_BITS_PER_WIDE_INT);
5643         }
5644
5645       value = build_int_cst_wide (type, val[1], val[0]);
5646       add_pending_init (purpose, value);
5647     }
5648
5649   constructor_incremental = 0;
5650 }
5651
5652 /* Return value of FIELD in pending initializer or zero if the field was
5653    not initialized yet.  */
5654
5655 static tree
5656 find_init_member (tree field)
5657 {
5658   struct init_node *p;
5659
5660   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5661     {
5662       if (constructor_incremental
5663           && tree_int_cst_lt (field, constructor_unfilled_index))
5664         set_nonincremental_init ();
5665
5666       p = constructor_pending_elts;
5667       while (p)
5668         {
5669           if (tree_int_cst_lt (field, p->purpose))
5670             p = p->left;
5671           else if (tree_int_cst_lt (p->purpose, field))
5672             p = p->right;
5673           else
5674             return p->value;
5675         }
5676     }
5677   else if (TREE_CODE (constructor_type) == RECORD_TYPE)
5678     {
5679       tree bitpos = bit_position (field);
5680
5681       if (constructor_incremental
5682           && (!constructor_unfilled_fields
5683               || tree_int_cst_lt (bitpos,
5684                                   bit_position (constructor_unfilled_fields))))
5685         set_nonincremental_init ();
5686
5687       p = constructor_pending_elts;
5688       while (p)
5689         {
5690           if (field == p->purpose)
5691             return p->value;
5692           else if (tree_int_cst_lt (bitpos, bit_position (p->purpose)))
5693             p = p->left;
5694           else
5695             p = p->right;
5696         }
5697     }
5698   else if (TREE_CODE (constructor_type) == UNION_TYPE)
5699     {
5700       if (constructor_elements
5701           && TREE_PURPOSE (constructor_elements) == field)
5702         return TREE_VALUE (constructor_elements);
5703     }
5704   return 0;
5705 }
5706
5707 /* "Output" the next constructor element.
5708    At top level, really output it to assembler code now.
5709    Otherwise, collect it in a list from which we will make a CONSTRUCTOR.
5710    TYPE is the data type that the containing data type wants here.
5711    FIELD is the field (a FIELD_DECL) or the index that this element fills.
5712    If VALUE is a string constant, STRICT_STRING is true if it is
5713    unparenthesized or we should not warn here for it being parenthesized.
5714    For other types of VALUE, STRICT_STRING is not used.
5715
5716    PENDING if non-nil means output pending elements that belong
5717    right after this element.  (PENDING is normally 1;
5718    it is 0 while outputting pending elements, to avoid recursion.)  */
5719
5720 static void
5721 output_init_element (tree value, bool strict_string, tree type, tree field,
5722                      int pending)
5723 {
5724   if (type == error_mark_node || value == error_mark_node)
5725     {
5726       constructor_erroneous = 1;
5727       return;
5728     }
5729   if (TREE_CODE (TREE_TYPE (value)) == FUNCTION_TYPE
5730       || (TREE_CODE (TREE_TYPE (value)) == ARRAY_TYPE
5731           && !(TREE_CODE (value) == STRING_CST
5732                && TREE_CODE (type) == ARRAY_TYPE
5733                && INTEGRAL_TYPE_P (TREE_TYPE (type)))
5734           && !comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (value)),
5735                          TYPE_MAIN_VARIANT (type))))
5736     value = default_conversion (value);
5737
5738   if (TREE_CODE (value) == COMPOUND_LITERAL_EXPR
5739       && require_constant_value && !flag_isoc99 && pending)
5740     {
5741       /* As an extension, allow initializing objects with static storage
5742          duration with compound literals (which are then treated just as
5743          the brace enclosed list they contain).  */
5744       tree decl = COMPOUND_LITERAL_EXPR_DECL (value);
5745       value = DECL_INITIAL (decl);
5746     }
5747
5748   if (value == error_mark_node)
5749     constructor_erroneous = 1;
5750   else if (!TREE_CONSTANT (value))
5751     constructor_constant = 0;
5752   else if (!initializer_constant_valid_p (value, TREE_TYPE (value))
5753            || ((TREE_CODE (constructor_type) == RECORD_TYPE
5754                 || TREE_CODE (constructor_type) == UNION_TYPE)
5755                && DECL_C_BIT_FIELD (field)
5756                && TREE_CODE (value) != INTEGER_CST))
5757     constructor_simple = 0;
5758
5759   if (!initializer_constant_valid_p (value, TREE_TYPE (value)))
5760     {
5761       if (require_constant_value)
5762         {
5763           error_init ("initializer element is not constant");
5764           value = error_mark_node;
5765         }
5766       else if (require_constant_elements)
5767         pedwarn ("initializer element is not computable at load time");
5768     }
5769
5770   /* If this field is empty (and not at the end of structure),
5771      don't do anything other than checking the initializer.  */
5772   if (field
5773       && (TREE_TYPE (field) == error_mark_node
5774           || (COMPLETE_TYPE_P (TREE_TYPE (field))
5775               && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))
5776               && (TREE_CODE (constructor_type) == ARRAY_TYPE
5777                   || TREE_CHAIN (field)))))
5778     return;
5779
5780   value = digest_init (type, value, strict_string, require_constant_value);
5781   if (value == error_mark_node)
5782     {
5783       constructor_erroneous = 1;
5784       return;
5785     }
5786
5787   /* If this element doesn't come next in sequence,
5788      put it on constructor_pending_elts.  */
5789   if (TREE_CODE (constructor_type) == ARRAY_TYPE
5790       && (!constructor_incremental
5791           || !tree_int_cst_equal (field, constructor_unfilled_index)))
5792     {
5793       if (constructor_incremental
5794           && tree_int_cst_lt (field, constructor_unfilled_index))
5795         set_nonincremental_init ();
5796
5797       add_pending_init (field, value);
5798       return;
5799     }
5800   else if (TREE_CODE (constructor_type) == RECORD_TYPE
5801            && (!constructor_incremental
5802                || field != constructor_unfilled_fields))
5803     {
5804       /* We do this for records but not for unions.  In a union,
5805          no matter which field is specified, it can be initialized
5806          right away since it starts at the beginning of the union.  */
5807       if (constructor_incremental)
5808         {
5809           if (!constructor_unfilled_fields)
5810             set_nonincremental_init ();
5811           else
5812             {
5813               tree bitpos, unfillpos;
5814
5815               bitpos = bit_position (field);
5816               unfillpos = bit_position (constructor_unfilled_fields);
5817
5818               if (tree_int_cst_lt (bitpos, unfillpos))
5819                 set_nonincremental_init ();
5820             }
5821         }
5822
5823       add_pending_init (field, value);
5824       return;
5825     }
5826   else if (TREE_CODE (constructor_type) == UNION_TYPE
5827            && constructor_elements)
5828     {
5829       if (TREE_SIDE_EFFECTS (TREE_VALUE (constructor_elements)))
5830         warning_init ("initialized field with side-effects overwritten");
5831
5832       /* We can have just one union field set.  */
5833       constructor_elements = 0;
5834     }
5835
5836   /* Otherwise, output this element either to
5837      constructor_elements or to the assembler file.  */
5838
5839   if (field && TREE_CODE (field) == INTEGER_CST)
5840     field = copy_node (field);
5841   constructor_elements
5842     = tree_cons (field, value, constructor_elements);
5843
5844   /* Advance the variable that indicates sequential elements output.  */
5845   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5846     constructor_unfilled_index
5847       = size_binop (PLUS_EXPR, constructor_unfilled_index,
5848                     bitsize_one_node);
5849   else if (TREE_CODE (constructor_type) == RECORD_TYPE)
5850     {
5851       constructor_unfilled_fields
5852         = TREE_CHAIN (constructor_unfilled_fields);
5853
5854       /* Skip any nameless bit fields.  */
5855       while (constructor_unfilled_fields != 0
5856              && DECL_C_BIT_FIELD (constructor_unfilled_fields)
5857              && DECL_NAME (constructor_unfilled_fields) == 0)
5858         constructor_unfilled_fields =
5859           TREE_CHAIN (constructor_unfilled_fields);
5860     }
5861   else if (TREE_CODE (constructor_type) == UNION_TYPE)
5862     constructor_unfilled_fields = 0;
5863
5864   /* Now output any pending elements which have become next.  */
5865   if (pending)
5866     output_pending_init_elements (0);
5867 }
5868
5869 /* Output any pending elements which have become next.
5870    As we output elements, constructor_unfilled_{fields,index}
5871    advances, which may cause other elements to become next;
5872    if so, they too are output.
5873
5874    If ALL is 0, we return when there are
5875    no more pending elements to output now.
5876
5877    If ALL is 1, we output space as necessary so that
5878    we can output all the pending elements.  */
5879
5880 static void
5881 output_pending_init_elements (int all)
5882 {
5883   struct init_node *elt = constructor_pending_elts;
5884   tree next;
5885
5886  retry:
5887
5888   /* Look through the whole pending tree.
5889      If we find an element that should be output now,
5890      output it.  Otherwise, set NEXT to the element
5891      that comes first among those still pending.  */
5892
5893   next = 0;
5894   while (elt)
5895     {
5896       if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5897         {
5898           if (tree_int_cst_equal (elt->purpose,
5899                                   constructor_unfilled_index))
5900             output_init_element (elt->value, true,
5901                                  TREE_TYPE (constructor_type),
5902                                  constructor_unfilled_index, 0);
5903           else if (tree_int_cst_lt (constructor_unfilled_index,
5904                                     elt->purpose))
5905             {
5906               /* Advance to the next smaller node.  */
5907               if (elt->left)
5908                 elt = elt->left;
5909               else
5910                 {
5911                   /* We have reached the smallest node bigger than the
5912                      current unfilled index.  Fill the space first.  */
5913                   next = elt->purpose;
5914                   break;
5915                 }
5916             }
5917           else
5918             {
5919               /* Advance to the next bigger node.  */
5920               if (elt->right)
5921                 elt = elt->right;
5922               else
5923                 {
5924                   /* We have reached the biggest node in a subtree.  Find
5925                      the parent of it, which is the next bigger node.  */
5926                   while (elt->parent && elt->parent->right == elt)
5927                     elt = elt->parent;
5928                   elt = elt->parent;
5929                   if (elt && tree_int_cst_lt (constructor_unfilled_index,
5930                                               elt->purpose))
5931                     {
5932                       next = elt->purpose;
5933                       break;
5934                     }
5935                 }
5936             }
5937         }
5938       else if (TREE_CODE (constructor_type) == RECORD_TYPE
5939                || TREE_CODE (constructor_type) == UNION_TYPE)
5940         {
5941           tree ctor_unfilled_bitpos, elt_bitpos;
5942
5943           /* If the current record is complete we are done.  */
5944           if (constructor_unfilled_fields == 0)
5945             break;
5946
5947           ctor_unfilled_bitpos = bit_position (constructor_unfilled_fields);
5948           elt_bitpos = bit_position (elt->purpose);
5949           /* We can't compare fields here because there might be empty
5950              fields in between.  */
5951           if (tree_int_cst_equal (elt_bitpos, ctor_unfilled_bitpos))
5952             {
5953               constructor_unfilled_fields = elt->purpose;
5954               output_init_element (elt->value, true, TREE_TYPE (elt->purpose),
5955                                    elt->purpose, 0);
5956             }
5957           else if (tree_int_cst_lt (ctor_unfilled_bitpos, elt_bitpos))
5958             {
5959               /* Advance to the next smaller node.  */
5960               if (elt->left)
5961                 elt = elt->left;
5962               else
5963                 {
5964                   /* We have reached the smallest node bigger than the
5965                      current unfilled field.  Fill the space first.  */
5966                   next = elt->purpose;
5967                   break;
5968                 }
5969             }
5970           else
5971             {
5972               /* Advance to the next bigger node.  */
5973               if (elt->right)
5974                 elt = elt->right;
5975               else
5976                 {
5977                   /* We have reached the biggest node in a subtree.  Find
5978                      the parent of it, which is the next bigger node.  */
5979                   while (elt->parent && elt->parent->right == elt)
5980                     elt = elt->parent;
5981                   elt = elt->parent;
5982                   if (elt
5983                       && (tree_int_cst_lt (ctor_unfilled_bitpos,
5984                                            bit_position (elt->purpose))))
5985                     {
5986                       next = elt->purpose;
5987                       break;
5988                     }
5989                 }
5990             }
5991         }
5992     }
5993
5994   /* Ordinarily return, but not if we want to output all
5995      and there are elements left.  */
5996   if (!(all && next != 0))
5997     return;
5998
5999   /* If it's not incremental, just skip over the gap, so that after
6000      jumping to retry we will output the next successive element.  */
6001   if (TREE_CODE (constructor_type) == RECORD_TYPE
6002       || TREE_CODE (constructor_type) == UNION_TYPE)
6003     constructor_unfilled_fields = next;
6004   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6005     constructor_unfilled_index = next;
6006
6007   /* ELT now points to the node in the pending tree with the next
6008      initializer to output.  */
6009   goto retry;
6010 }
6011 \f
6012 /* Add one non-braced element to the current constructor level.
6013    This adjusts the current position within the constructor's type.
6014    This may also start or terminate implicit levels
6015    to handle a partly-braced initializer.
6016
6017    Once this has found the correct level for the new element,
6018    it calls output_init_element.  */
6019
6020 void
6021 process_init_element (struct c_expr value)
6022 {
6023   tree orig_value = value.value;
6024   int string_flag = orig_value != 0 && TREE_CODE (orig_value) == STRING_CST;
6025   bool strict_string = value.original_code == STRING_CST;
6026
6027   designator_depth = 0;
6028   designator_errorneous = 0;
6029
6030   /* Handle superfluous braces around string cst as in
6031      char x[] = {"foo"}; */
6032   if (string_flag
6033       && constructor_type
6034       && TREE_CODE (constructor_type) == ARRAY_TYPE
6035       && INTEGRAL_TYPE_P (TREE_TYPE (constructor_type))
6036       && integer_zerop (constructor_unfilled_index))
6037     {
6038       if (constructor_stack->replacement_value.value)
6039         error_init ("excess elements in char array initializer");
6040       constructor_stack->replacement_value = value;
6041       return;
6042     }
6043
6044   if (constructor_stack->replacement_value.value != 0)
6045     {
6046       error_init ("excess elements in struct initializer");
6047       return;
6048     }
6049
6050   /* Ignore elements of a brace group if it is entirely superfluous
6051      and has already been diagnosed.  */
6052   if (constructor_type == 0)
6053     return;
6054
6055   /* If we've exhausted any levels that didn't have braces,
6056      pop them now.  */
6057   while (constructor_stack->implicit)
6058     {
6059       if ((TREE_CODE (constructor_type) == RECORD_TYPE
6060            || TREE_CODE (constructor_type) == UNION_TYPE)
6061           && constructor_fields == 0)
6062         process_init_element (pop_init_level (1));
6063       else if (TREE_CODE (constructor_type) == ARRAY_TYPE
6064                && (constructor_max_index == 0
6065                    || tree_int_cst_lt (constructor_max_index,
6066                                        constructor_index)))
6067         process_init_element (pop_init_level (1));
6068       else
6069         break;
6070     }
6071
6072   /* In the case of [LO ... HI] = VALUE, only evaluate VALUE once.  */
6073   if (constructor_range_stack)
6074     {
6075       /* If value is a compound literal and we'll be just using its
6076          content, don't put it into a SAVE_EXPR.  */
6077       if (TREE_CODE (value.value) != COMPOUND_LITERAL_EXPR
6078           || !require_constant_value
6079           || flag_isoc99)
6080         value.value = save_expr (value.value);
6081     }
6082
6083   while (1)
6084     {
6085       if (TREE_CODE (constructor_type) == RECORD_TYPE)
6086         {
6087           tree fieldtype;
6088           enum tree_code fieldcode;
6089
6090           if (constructor_fields == 0)
6091             {
6092               pedwarn_init ("excess elements in struct initializer");
6093               break;
6094             }
6095
6096           fieldtype = TREE_TYPE (constructor_fields);
6097           if (fieldtype != error_mark_node)
6098             fieldtype = TYPE_MAIN_VARIANT (fieldtype);
6099           fieldcode = TREE_CODE (fieldtype);
6100
6101           /* Error for non-static initialization of a flexible array member.  */
6102           if (fieldcode == ARRAY_TYPE
6103               && !require_constant_value
6104               && TYPE_SIZE (fieldtype) == NULL_TREE
6105               && TREE_CHAIN (constructor_fields) == NULL_TREE)
6106             {
6107               error_init ("non-static initialization of a flexible array member");
6108               break;
6109             }
6110
6111           /* Accept a string constant to initialize a subarray.  */
6112           if (value.value != 0
6113               && fieldcode == ARRAY_TYPE
6114               && INTEGRAL_TYPE_P (TREE_TYPE (fieldtype))
6115               && string_flag)
6116             value.value = orig_value;
6117           /* Otherwise, if we have come to a subaggregate,
6118              and we don't have an element of its type, push into it.  */
6119           else if (value.value != 0
6120                    && value.value != error_mark_node
6121                    && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != fieldtype
6122                    && (fieldcode == RECORD_TYPE || fieldcode == ARRAY_TYPE
6123                        || fieldcode == UNION_TYPE))
6124             {
6125               push_init_level (1);
6126               continue;
6127             }
6128
6129           if (value.value)
6130             {
6131               push_member_name (constructor_fields);
6132               output_init_element (value.value, strict_string,
6133                                    fieldtype, constructor_fields, 1);
6134               RESTORE_SPELLING_DEPTH (constructor_depth);
6135             }
6136           else
6137             /* Do the bookkeeping for an element that was
6138                directly output as a constructor.  */
6139             {
6140               /* For a record, keep track of end position of last field.  */
6141               if (DECL_SIZE (constructor_fields))
6142                 constructor_bit_index
6143                   = size_binop (PLUS_EXPR,
6144                                 bit_position (constructor_fields),
6145                                 DECL_SIZE (constructor_fields));
6146
6147               /* If the current field was the first one not yet written out,
6148                  it isn't now, so update.  */
6149               if (constructor_unfilled_fields == constructor_fields)
6150                 {
6151                   constructor_unfilled_fields = TREE_CHAIN (constructor_fields);
6152                   /* Skip any nameless bit fields.  */
6153                   while (constructor_unfilled_fields != 0
6154                          && DECL_C_BIT_FIELD (constructor_unfilled_fields)
6155                          && DECL_NAME (constructor_unfilled_fields) == 0)
6156                     constructor_unfilled_fields =
6157                       TREE_CHAIN (constructor_unfilled_fields);
6158                 }
6159             }
6160
6161           constructor_fields = TREE_CHAIN (constructor_fields);
6162           /* Skip any nameless bit fields at the beginning.  */
6163           while (constructor_fields != 0
6164                  && DECL_C_BIT_FIELD (constructor_fields)
6165                  && DECL_NAME (constructor_fields) == 0)
6166             constructor_fields = TREE_CHAIN (constructor_fields);
6167         }
6168       else if (TREE_CODE (constructor_type) == UNION_TYPE)
6169         {
6170           tree fieldtype;
6171           enum tree_code fieldcode;
6172
6173           if (constructor_fields == 0)
6174             {
6175               pedwarn_init ("excess elements in union initializer");
6176               break;
6177             }
6178
6179           fieldtype = TREE_TYPE (constructor_fields);
6180           if (fieldtype != error_mark_node)
6181             fieldtype = TYPE_MAIN_VARIANT (fieldtype);
6182           fieldcode = TREE_CODE (fieldtype);
6183
6184           /* Warn that traditional C rejects initialization of unions.
6185              We skip the warning if the value is zero.  This is done
6186              under the assumption that the zero initializer in user
6187              code appears conditioned on e.g. __STDC__ to avoid
6188              "missing initializer" warnings and relies on default
6189              initialization to zero in the traditional C case.
6190              We also skip the warning if the initializer is designated,
6191              again on the assumption that this must be conditional on
6192              __STDC__ anyway (and we've already complained about the
6193              member-designator already).  */
6194           if (warn_traditional && !in_system_header && !constructor_designated
6195               && !(value.value && (integer_zerop (value.value)
6196                                    || real_zerop (value.value))))
6197             warning (0, "traditional C rejects initialization of unions");
6198
6199           /* Accept a string constant to initialize a subarray.  */
6200           if (value.value != 0
6201               && fieldcode == ARRAY_TYPE
6202               && INTEGRAL_TYPE_P (TREE_TYPE (fieldtype))
6203               && string_flag)
6204             value.value = orig_value;
6205           /* Otherwise, if we have come to a subaggregate,
6206              and we don't have an element of its type, push into it.  */
6207           else if (value.value != 0
6208                    && value.value != error_mark_node
6209                    && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != fieldtype
6210                    && (fieldcode == RECORD_TYPE || fieldcode == ARRAY_TYPE
6211                        || fieldcode == UNION_TYPE))
6212             {
6213               push_init_level (1);
6214               continue;
6215             }
6216
6217           if (value.value)
6218             {
6219               push_member_name (constructor_fields);
6220               output_init_element (value.value, strict_string,
6221                                    fieldtype, constructor_fields, 1);
6222               RESTORE_SPELLING_DEPTH (constructor_depth);
6223             }
6224           else
6225             /* Do the bookkeeping for an element that was
6226                directly output as a constructor.  */
6227             {
6228               constructor_bit_index = DECL_SIZE (constructor_fields);
6229               constructor_unfilled_fields = TREE_CHAIN (constructor_fields);
6230             }
6231
6232           constructor_fields = 0;
6233         }
6234       else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6235         {
6236           tree elttype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
6237           enum tree_code eltcode = TREE_CODE (elttype);
6238
6239           /* Accept a string constant to initialize a subarray.  */
6240           if (value.value != 0
6241               && eltcode == ARRAY_TYPE
6242               && INTEGRAL_TYPE_P (TREE_TYPE (elttype))
6243               && string_flag)
6244             value.value = orig_value;
6245           /* Otherwise, if we have come to a subaggregate,
6246              and we don't have an element of its type, push into it.  */
6247           else if (value.value != 0
6248                    && value.value != error_mark_node
6249                    && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != elttype
6250                    && (eltcode == RECORD_TYPE || eltcode == ARRAY_TYPE
6251                        || eltcode == UNION_TYPE))
6252             {
6253               push_init_level (1);
6254               continue;
6255             }
6256
6257           if (constructor_max_index != 0
6258               && (tree_int_cst_lt (constructor_max_index, constructor_index)
6259                   || integer_all_onesp (constructor_max_index)))
6260             {
6261               pedwarn_init ("excess elements in array initializer");
6262               break;
6263             }
6264
6265           /* Now output the actual element.  */
6266           if (value.value)
6267             {
6268               push_array_bounds (tree_low_cst (constructor_index, 0));
6269               output_init_element (value.value, strict_string,
6270                                    elttype, constructor_index, 1);
6271               RESTORE_SPELLING_DEPTH (constructor_depth);
6272             }
6273
6274           constructor_index
6275             = size_binop (PLUS_EXPR, constructor_index, bitsize_one_node);
6276
6277           if (!value.value)
6278             /* If we are doing the bookkeeping for an element that was
6279                directly output as a constructor, we must update
6280                constructor_unfilled_index.  */
6281             constructor_unfilled_index = constructor_index;
6282         }
6283       else if (TREE_CODE (constructor_type) == VECTOR_TYPE)
6284         {
6285           tree elttype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
6286
6287          /* Do a basic check of initializer size.  Note that vectors
6288             always have a fixed size derived from their type.  */
6289           if (tree_int_cst_lt (constructor_max_index, constructor_index))
6290             {
6291               pedwarn_init ("excess elements in vector initializer");
6292               break;
6293             }
6294
6295           /* Now output the actual element.  */
6296           if (value.value)
6297             output_init_element (value.value, strict_string,
6298                                  elttype, constructor_index, 1);
6299
6300           constructor_index
6301             = size_binop (PLUS_EXPR, constructor_index, bitsize_one_node);
6302
6303           if (!value.value)
6304             /* If we are doing the bookkeeping for an element that was
6305                directly output as a constructor, we must update
6306                constructor_unfilled_index.  */
6307             constructor_unfilled_index = constructor_index;
6308         }
6309
6310       /* Handle the sole element allowed in a braced initializer
6311          for a scalar variable.  */
6312       else if (constructor_type != error_mark_node
6313                && constructor_fields == 0)
6314         {
6315           pedwarn_init ("excess elements in scalar initializer");
6316           break;
6317         }
6318       else
6319         {
6320           if (value.value)
6321             output_init_element (value.value, strict_string,
6322                                  constructor_type, NULL_TREE, 1);
6323           constructor_fields = 0;
6324         }
6325
6326       /* Handle range initializers either at this level or anywhere higher
6327          in the designator stack.  */
6328       if (constructor_range_stack)
6329         {
6330           struct constructor_range_stack *p, *range_stack;
6331           int finish = 0;
6332
6333           range_stack = constructor_range_stack;
6334           constructor_range_stack = 0;
6335           while (constructor_stack != range_stack->stack)
6336             {
6337               gcc_assert (constructor_stack->implicit);
6338               process_init_element (pop_init_level (1));
6339             }
6340           for (p = range_stack;
6341                !p->range_end || tree_int_cst_equal (p->index, p->range_end);
6342                p = p->prev)
6343             {
6344               gcc_assert (constructor_stack->implicit);
6345               process_init_element (pop_init_level (1));
6346             }
6347
6348           p->index = size_binop (PLUS_EXPR, p->index, bitsize_one_node);
6349           if (tree_int_cst_equal (p->index, p->range_end) && !p->prev)
6350             finish = 1;
6351
6352           while (1)
6353             {
6354               constructor_index = p->index;
6355               constructor_fields = p->fields;
6356               if (finish && p->range_end && p->index == p->range_start)
6357                 {
6358                   finish = 0;
6359                   p->prev = 0;
6360                 }
6361               p = p->next;
6362               if (!p)
6363                 break;
6364               push_init_level (2);
6365               p->stack = constructor_stack;
6366               if (p->range_end && tree_int_cst_equal (p->index, p->range_end))
6367                 p->index = p->range_start;
6368             }
6369
6370           if (!finish)
6371             constructor_range_stack = range_stack;
6372           continue;
6373         }
6374
6375       break;
6376     }
6377
6378   constructor_range_stack = 0;
6379 }
6380 \f
6381 /* Build a complete asm-statement, whose components are a CV_QUALIFIER
6382    (guaranteed to be 'volatile' or null) and ARGS (represented using
6383    an ASM_EXPR node).  */
6384 tree
6385 build_asm_stmt (tree cv_qualifier, tree args)
6386 {
6387   if (!ASM_VOLATILE_P (args) && cv_qualifier)
6388     ASM_VOLATILE_P (args) = 1;
6389   return add_stmt (args);
6390 }
6391
6392 /* Build an asm-expr, whose components are a STRING, some OUTPUTS,
6393    some INPUTS, and some CLOBBERS.  The latter three may be NULL.
6394    SIMPLE indicates whether there was anything at all after the
6395    string in the asm expression -- asm("blah") and asm("blah" : )
6396    are subtly different.  We use a ASM_EXPR node to represent this.  */
6397 tree
6398 build_asm_expr (tree string, tree outputs, tree inputs, tree clobbers,
6399                 bool simple)
6400 {
6401   tree tail;
6402   tree args;
6403   int i;
6404   const char *constraint;
6405   const char **oconstraints;
6406   bool allows_mem, allows_reg, is_inout;
6407   int ninputs, noutputs;
6408
6409   ninputs = list_length (inputs);
6410   noutputs = list_length (outputs);
6411   oconstraints = (const char **) alloca (noutputs * sizeof (const char *));
6412
6413   string = resolve_asm_operand_names (string, outputs, inputs);
6414
6415   /* Remove output conversions that change the type but not the mode.  */
6416   for (i = 0, tail = outputs; tail; ++i, tail = TREE_CHAIN (tail))
6417     {
6418       tree output = TREE_VALUE (tail);
6419
6420       /* ??? Really, this should not be here.  Users should be using a
6421          proper lvalue, dammit.  But there's a long history of using casts
6422          in the output operands.  In cases like longlong.h, this becomes a
6423          primitive form of typechecking -- if the cast can be removed, then
6424          the output operand had a type of the proper width; otherwise we'll
6425          get an error.  Gross, but ...  */
6426       STRIP_NOPS (output);
6427
6428       if (!lvalue_or_else (output, lv_asm))
6429         output = error_mark_node;
6430
6431       constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tail)));
6432       oconstraints[i] = constraint;
6433
6434       if (parse_output_constraint (&constraint, i, ninputs, noutputs,
6435                                    &allows_mem, &allows_reg, &is_inout))
6436         {
6437           /* If the operand is going to end up in memory,
6438              mark it addressable.  */
6439           if (!allows_reg && !c_mark_addressable (output))
6440             output = error_mark_node;
6441         }
6442       else
6443         output = error_mark_node;
6444
6445       TREE_VALUE (tail) = output;
6446     }
6447
6448   /* Perform default conversions on array and function inputs.
6449      Don't do this for other types as it would screw up operands
6450      expected to be in memory.  */
6451   for (i = 0, tail = inputs; tail; ++i, tail = TREE_CHAIN (tail))
6452     {
6453       tree input;
6454
6455       constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tail)));
6456       input = TREE_VALUE (tail);
6457
6458       input = default_function_array_conversion (input);
6459
6460       if (parse_input_constraint (&constraint, i, ninputs, noutputs, 0,
6461                                   oconstraints, &allows_mem, &allows_reg))
6462         {
6463           /* If the operand is going to end up in memory,
6464              mark it addressable.  */
6465           if (!allows_reg && allows_mem)
6466             {
6467               /* Strip the nops as we allow this case.  FIXME, this really
6468                  should be rejected or made deprecated.  */
6469               STRIP_NOPS (input);
6470               if (!c_mark_addressable (input))
6471                 input = error_mark_node;
6472           }
6473         }
6474       else
6475         input = error_mark_node;
6476
6477       TREE_VALUE (tail) = input;
6478     }
6479
6480   args = build_stmt (ASM_EXPR, string, outputs, inputs, clobbers);
6481
6482   /* Simple asm statements are treated as volatile.  */
6483   if (simple)
6484     {
6485       ASM_VOLATILE_P (args) = 1;
6486       ASM_INPUT_P (args) = 1;
6487     }
6488
6489   return args;
6490 }
6491 \f
6492 /* Generate a goto statement to LABEL.  */
6493
6494 tree
6495 c_finish_goto_label (tree label)
6496 {
6497   tree decl = lookup_label (label);
6498   if (!decl)
6499     return NULL_TREE;
6500
6501   if (C_DECL_UNJUMPABLE_STMT_EXPR (decl))
6502     {
6503       error ("jump into statement expression");
6504       return NULL_TREE;
6505     }
6506
6507   if (C_DECL_UNJUMPABLE_VM (decl))
6508     {
6509       error ("jump into scope of identifier with variably modified type");
6510       return NULL_TREE;
6511     }
6512
6513   if (!C_DECL_UNDEFINABLE_STMT_EXPR (decl))
6514     {
6515       /* No jump from outside this statement expression context, so
6516          record that there is a jump from within this context.  */
6517       struct c_label_list *nlist;
6518       nlist = XOBNEW (&parser_obstack, struct c_label_list);
6519       nlist->next = label_context_stack_se->labels_used;
6520       nlist->label = decl;
6521       label_context_stack_se->labels_used = nlist;
6522     }
6523
6524   if (!C_DECL_UNDEFINABLE_VM (decl))
6525     {
6526       /* No jump from outside this context context of identifiers with
6527          variably modified type, so record that there is a jump from
6528          within this context.  */
6529       struct c_label_list *nlist;
6530       nlist = XOBNEW (&parser_obstack, struct c_label_list);
6531       nlist->next = label_context_stack_vm->labels_used;
6532       nlist->label = decl;
6533       label_context_stack_vm->labels_used = nlist;
6534     }
6535
6536   TREE_USED (decl) = 1;
6537   return add_stmt (build1 (GOTO_EXPR, void_type_node, decl));
6538 }
6539
6540 /* Generate a computed goto statement to EXPR.  */
6541
6542 tree
6543 c_finish_goto_ptr (tree expr)
6544 {
6545   if (pedantic)
6546     pedwarn ("ISO C forbids %<goto *expr;%>");
6547   expr = convert (ptr_type_node, expr);
6548   return add_stmt (build1 (GOTO_EXPR, void_type_node, expr));
6549 }
6550
6551 /* Generate a C `return' statement.  RETVAL is the expression for what
6552    to return, or a null pointer for `return;' with no value.  */
6553
6554 tree
6555 c_finish_return (tree retval)
6556 {
6557   tree valtype = TREE_TYPE (TREE_TYPE (current_function_decl));
6558
6559   if (TREE_THIS_VOLATILE (current_function_decl))
6560     warning (0, "function declared %<noreturn%> has a %<return%> statement");
6561
6562   if (!retval)
6563     {
6564       current_function_returns_null = 1;
6565       if ((warn_return_type || flag_isoc99)
6566           && valtype != 0 && TREE_CODE (valtype) != VOID_TYPE)
6567         pedwarn_c99 ("%<return%> with no value, in "
6568                      "function returning non-void");
6569     }
6570   else if (valtype == 0 || TREE_CODE (valtype) == VOID_TYPE)
6571     {
6572       current_function_returns_null = 1;
6573       if (pedantic || TREE_CODE (TREE_TYPE (retval)) != VOID_TYPE)
6574         pedwarn ("%<return%> with a value, in function returning void");
6575     }
6576   else
6577     {
6578       tree t = convert_for_assignment (valtype, retval, ic_return,
6579                                        NULL_TREE, NULL_TREE, 0);
6580       tree res = DECL_RESULT (current_function_decl);
6581       tree inner;
6582
6583       current_function_returns_value = 1;
6584       if (t == error_mark_node)
6585         return NULL_TREE;
6586
6587       inner = t = convert (TREE_TYPE (res), t);
6588
6589       /* Strip any conversions, additions, and subtractions, and see if
6590          we are returning the address of a local variable.  Warn if so.  */
6591       while (1)
6592         {
6593           switch (TREE_CODE (inner))
6594             {
6595             case NOP_EXPR:   case NON_LVALUE_EXPR:  case CONVERT_EXPR:
6596             case PLUS_EXPR:
6597               inner = TREE_OPERAND (inner, 0);
6598               continue;
6599
6600             case MINUS_EXPR:
6601               /* If the second operand of the MINUS_EXPR has a pointer
6602                  type (or is converted from it), this may be valid, so
6603                  don't give a warning.  */
6604               {
6605                 tree op1 = TREE_OPERAND (inner, 1);
6606
6607                 while (!POINTER_TYPE_P (TREE_TYPE (op1))
6608                        && (TREE_CODE (op1) == NOP_EXPR
6609                            || TREE_CODE (op1) == NON_LVALUE_EXPR
6610                            || TREE_CODE (op1) == CONVERT_EXPR))
6611                   op1 = TREE_OPERAND (op1, 0);
6612
6613                 if (POINTER_TYPE_P (TREE_TYPE (op1)))
6614                   break;
6615
6616                 inner = TREE_OPERAND (inner, 0);
6617                 continue;
6618               }
6619
6620             case ADDR_EXPR:
6621               inner = TREE_OPERAND (inner, 0);
6622
6623               while (REFERENCE_CLASS_P (inner)
6624                      && TREE_CODE (inner) != INDIRECT_REF)
6625                 inner = TREE_OPERAND (inner, 0);
6626
6627               if (DECL_P (inner)
6628                   && !DECL_EXTERNAL (inner)
6629                   && !TREE_STATIC (inner)
6630                   && DECL_CONTEXT (inner) == current_function_decl)
6631                 warning (0, "function returns address of local variable");
6632               break;
6633
6634             default:
6635               break;
6636             }
6637
6638           break;
6639         }
6640
6641       retval = build2 (MODIFY_EXPR, TREE_TYPE (res), res, t);
6642     }
6643
6644   return add_stmt (build_stmt (RETURN_EXPR, retval));
6645 }
6646 \f
6647 struct c_switch {
6648   /* The SWITCH_EXPR being built.  */
6649   tree switch_expr;
6650
6651   /* The original type of the testing expression, i.e. before the
6652      default conversion is applied.  */
6653   tree orig_type;
6654
6655   /* A splay-tree mapping the low element of a case range to the high
6656      element, or NULL_TREE if there is no high element.  Used to
6657      determine whether or not a new case label duplicates an old case
6658      label.  We need a tree, rather than simply a hash table, because
6659      of the GNU case range extension.  */
6660   splay_tree cases;
6661
6662   /* Number of nested statement expressions within this switch
6663      statement; if nonzero, case and default labels may not
6664      appear.  */
6665   unsigned int blocked_stmt_expr;
6666
6667   /* Scope of outermost declarations of identifiers with variably
6668      modified type within this switch statement; if nonzero, case and
6669      default labels may not appear.  */
6670   unsigned int blocked_vm;
6671
6672   /* The next node on the stack.  */
6673   struct c_switch *next;
6674 };
6675
6676 /* A stack of the currently active switch statements.  The innermost
6677    switch statement is on the top of the stack.  There is no need to
6678    mark the stack for garbage collection because it is only active
6679    during the processing of the body of a function, and we never
6680    collect at that point.  */
6681
6682 struct c_switch *c_switch_stack;
6683
6684 /* Start a C switch statement, testing expression EXP.  Return the new
6685    SWITCH_EXPR.  */
6686
6687 tree
6688 c_start_case (tree exp)
6689 {
6690   enum tree_code code;
6691   tree type, orig_type = error_mark_node;
6692   struct c_switch *cs;
6693
6694   if (exp != error_mark_node)
6695     {
6696       code = TREE_CODE (TREE_TYPE (exp));
6697       orig_type = TREE_TYPE (exp);
6698
6699       if (!INTEGRAL_TYPE_P (orig_type)
6700           && code != ERROR_MARK)
6701         {
6702           error ("switch quantity not an integer");
6703           exp = integer_zero_node;
6704           orig_type = error_mark_node;
6705         }
6706       else
6707         {
6708           type = TYPE_MAIN_VARIANT (TREE_TYPE (exp));
6709
6710           if (warn_traditional && !in_system_header
6711               && (type == long_integer_type_node
6712                   || type == long_unsigned_type_node))
6713             warning (0, "%<long%> switch expression not converted to "
6714                      "%<int%> in ISO C");
6715
6716           exp = default_conversion (exp);
6717           type = TREE_TYPE (exp);
6718         }
6719     }
6720
6721   /* Add this new SWITCH_EXPR to the stack.  */
6722   cs = XNEW (struct c_switch);
6723   cs->switch_expr = build3 (SWITCH_EXPR, orig_type, exp, NULL_TREE, NULL_TREE);
6724   cs->orig_type = orig_type;
6725   cs->cases = splay_tree_new (case_compare, NULL, NULL);
6726   cs->blocked_stmt_expr = 0;
6727   cs->blocked_vm = 0;
6728   cs->next = c_switch_stack;
6729   c_switch_stack = cs;
6730
6731   return add_stmt (cs->switch_expr);
6732 }
6733
6734 /* Process a case label.  */
6735
6736 tree
6737 do_case (tree low_value, tree high_value)
6738 {
6739   tree label = NULL_TREE;
6740
6741   if (c_switch_stack && !c_switch_stack->blocked_stmt_expr
6742       && !c_switch_stack->blocked_vm)
6743     {
6744       label = c_add_case_label (c_switch_stack->cases,
6745                                 SWITCH_COND (c_switch_stack->switch_expr),
6746                                 c_switch_stack->orig_type,
6747                                 low_value, high_value);
6748       if (label == error_mark_node)
6749         label = NULL_TREE;
6750     }
6751   else if (c_switch_stack && c_switch_stack->blocked_stmt_expr)
6752     {
6753       if (low_value)
6754         error ("case label in statement expression not containing "
6755                "enclosing switch statement");
6756       else
6757         error ("%<default%> label in statement expression not containing "
6758                "enclosing switch statement");
6759     }
6760   else if (c_switch_stack && c_switch_stack->blocked_vm)
6761     {
6762       if (low_value)
6763         error ("case label in scope of identifier with variably modified "
6764                "type not containing enclosing switch statement");
6765       else
6766         error ("%<default%> label in scope of identifier with variably "
6767                "modified type not containing enclosing switch statement");
6768     }
6769   else if (low_value)
6770     error ("case label not within a switch statement");
6771   else
6772     error ("%<default%> label not within a switch statement");
6773
6774   return label;
6775 }
6776
6777 /* Finish the switch statement.  */
6778
6779 void
6780 c_finish_case (tree body)
6781 {
6782   struct c_switch *cs = c_switch_stack;
6783   location_t switch_location;
6784
6785   SWITCH_BODY (cs->switch_expr) = body;
6786
6787   /* We must not be within a statement expression nested in the switch
6788      at this point; we might, however, be within the scope of an
6789      identifier with variably modified type nested in the switch.  */
6790   gcc_assert (!cs->blocked_stmt_expr);
6791
6792   /* Emit warnings as needed.  */
6793   if (EXPR_HAS_LOCATION (cs->switch_expr))
6794     switch_location = EXPR_LOCATION (cs->switch_expr);
6795   else
6796     switch_location = input_location;
6797   c_do_switch_warnings (cs->cases, switch_location,
6798                         TREE_TYPE (cs->switch_expr),
6799                         SWITCH_COND (cs->switch_expr));
6800
6801   /* Pop the stack.  */
6802   c_switch_stack = cs->next;
6803   splay_tree_delete (cs->cases);
6804   XDELETE (cs);
6805 }
6806 \f
6807 /* Emit an if statement.  IF_LOCUS is the location of the 'if'.  COND,
6808    THEN_BLOCK and ELSE_BLOCK are expressions to be used; ELSE_BLOCK
6809    may be null.  NESTED_IF is true if THEN_BLOCK contains another IF
6810    statement, and was not surrounded with parenthesis.  */
6811
6812 void
6813 c_finish_if_stmt (location_t if_locus, tree cond, tree then_block,
6814                   tree else_block, bool nested_if)
6815 {
6816   tree stmt;
6817
6818   /* Diagnose an ambiguous else if if-then-else is nested inside if-then.  */
6819   if (warn_parentheses && nested_if && else_block == NULL)
6820     {
6821       tree inner_if = then_block;
6822
6823       /* We know from the grammar productions that there is an IF nested
6824          within THEN_BLOCK.  Due to labels and c99 conditional declarations,
6825          it might not be exactly THEN_BLOCK, but should be the last
6826          non-container statement within.  */
6827       while (1)
6828         switch (TREE_CODE (inner_if))
6829           {
6830           case COND_EXPR:
6831             goto found;
6832           case BIND_EXPR:
6833             inner_if = BIND_EXPR_BODY (inner_if);
6834             break;
6835           case STATEMENT_LIST:
6836             inner_if = expr_last (then_block);
6837             break;
6838           case TRY_FINALLY_EXPR:
6839           case TRY_CATCH_EXPR:
6840             inner_if = TREE_OPERAND (inner_if, 0);
6841             break;
6842           default:
6843             gcc_unreachable ();
6844           }
6845     found:
6846
6847       if (COND_EXPR_ELSE (inner_if))
6848          warning (0, "%Hsuggest explicit braces to avoid ambiguous %<else%>",
6849                   &if_locus);
6850     }
6851
6852   /* Diagnose ";" via the special empty statement node that we create.  */
6853   if (extra_warnings)
6854     {
6855       if (TREE_CODE (then_block) == NOP_EXPR && !TREE_TYPE (then_block))
6856         {
6857           if (!else_block)
6858             warning (0, "%Hempty body in an if-statement",
6859                      EXPR_LOCUS (then_block));
6860           then_block = alloc_stmt_list ();
6861         }
6862       if (else_block
6863           && TREE_CODE (else_block) == NOP_EXPR
6864           && !TREE_TYPE (else_block))
6865         {
6866           warning (0, "%Hempty body in an else-statement",
6867                    EXPR_LOCUS (else_block));
6868           else_block = alloc_stmt_list ();
6869         }
6870     }
6871
6872   stmt = build3 (COND_EXPR, NULL_TREE, cond, then_block, else_block);
6873   SET_EXPR_LOCATION (stmt, if_locus);
6874   add_stmt (stmt);
6875 }
6876
6877 /* Emit a general-purpose loop construct.  START_LOCUS is the location of
6878    the beginning of the loop.  COND is the loop condition.  COND_IS_FIRST
6879    is false for DO loops.  INCR is the FOR increment expression.  BODY is
6880    the statement controlled by the loop.  BLAB is the break label.  CLAB is
6881    the continue label.  Everything is allowed to be NULL.  */
6882
6883 void
6884 c_finish_loop (location_t start_locus, tree cond, tree incr, tree body,
6885                tree blab, tree clab, bool cond_is_first)
6886 {
6887   tree entry = NULL, exit = NULL, t;
6888
6889   /* If the condition is zero don't generate a loop construct.  */
6890   if (cond && integer_zerop (cond))
6891     {
6892       if (cond_is_first)
6893         {
6894           t = build_and_jump (&blab);
6895           SET_EXPR_LOCATION (t, start_locus);
6896           add_stmt (t);
6897         }
6898     }
6899   else
6900     {
6901       tree top = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
6902
6903       /* If we have an exit condition, then we build an IF with gotos either
6904          out of the loop, or to the top of it.  If there's no exit condition,
6905          then we just build a jump back to the top.  */
6906       exit = build_and_jump (&LABEL_EXPR_LABEL (top));
6907
6908       if (cond && !integer_nonzerop (cond))
6909         {
6910           /* Canonicalize the loop condition to the end.  This means
6911              generating a branch to the loop condition.  Reuse the
6912              continue label, if possible.  */
6913           if (cond_is_first)
6914             {
6915               if (incr || !clab)
6916                 {
6917                   entry = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
6918                   t = build_and_jump (&LABEL_EXPR_LABEL (entry));
6919                 }
6920               else
6921                 t = build1 (GOTO_EXPR, void_type_node, clab);
6922               SET_EXPR_LOCATION (t, start_locus);
6923               add_stmt (t);
6924             }
6925
6926           t = build_and_jump (&blab);
6927           exit = build3 (COND_EXPR, void_type_node, cond, exit, t);
6928           exit = fold (exit);
6929           if (cond_is_first)
6930             SET_EXPR_LOCATION (exit, start_locus);
6931           else
6932             SET_EXPR_LOCATION (exit, input_location);
6933         }
6934
6935       add_stmt (top);
6936     }
6937
6938   if (body)
6939     add_stmt (body);
6940   if (clab)
6941     add_stmt (build1 (LABEL_EXPR, void_type_node, clab));
6942   if (incr)
6943     add_stmt (incr);
6944   if (entry)
6945     add_stmt (entry);
6946   if (exit)
6947     add_stmt (exit);
6948   if (blab)
6949     add_stmt (build1 (LABEL_EXPR, void_type_node, blab));
6950 }
6951
6952 tree
6953 c_finish_bc_stmt (tree *label_p, bool is_break)
6954 {
6955   bool skip;
6956   tree label = *label_p;
6957
6958   /* In switch statements break is sometimes stylistically used after
6959      a return statement.  This can lead to spurious warnings about
6960      control reaching the end of a non-void function when it is
6961      inlined.  Note that we are calling block_may_fallthru with
6962      language specific tree nodes; this works because
6963      block_may_fallthru returns true when given something it does not
6964      understand.  */
6965   skip = !block_may_fallthru (cur_stmt_list);
6966
6967   if (!label)
6968     {
6969       if (!skip)
6970         *label_p = label = create_artificial_label ();
6971     }
6972   else if (TREE_CODE (label) != LABEL_DECL)
6973     {
6974       if (is_break)
6975         error ("break statement not within loop or switch");
6976       else
6977         error ("continue statement not within a loop");
6978       return NULL_TREE;
6979     }
6980
6981   if (skip)
6982     return NULL_TREE;
6983
6984   return add_stmt (build1 (GOTO_EXPR, void_type_node, label));
6985 }
6986
6987 /* A helper routine for c_process_expr_stmt and c_finish_stmt_expr.  */
6988
6989 static void
6990 emit_side_effect_warnings (tree expr)
6991 {
6992   if (expr == error_mark_node)
6993     ;
6994   else if (!TREE_SIDE_EFFECTS (expr))
6995     {
6996       if (!VOID_TYPE_P (TREE_TYPE (expr)) && !TREE_NO_WARNING (expr))
6997         warning (0, "%Hstatement with no effect",
6998                  EXPR_HAS_LOCATION (expr) ? EXPR_LOCUS (expr) : &input_location);
6999     }
7000   else if (warn_unused_value)
7001     warn_if_unused_value (expr, input_location);
7002 }
7003
7004 /* Process an expression as if it were a complete statement.  Emit
7005    diagnostics, but do not call ADD_STMT.  */
7006
7007 tree
7008 c_process_expr_stmt (tree expr)
7009 {
7010   if (!expr)
7011     return NULL_TREE;
7012
7013   /* Do default conversion if safe and possibly important,
7014      in case within ({...}).  */
7015   if ((TREE_CODE (TREE_TYPE (expr)) == ARRAY_TYPE
7016        && (flag_isoc99 || lvalue_p (expr)))
7017       || TREE_CODE (TREE_TYPE (expr)) == FUNCTION_TYPE)
7018     expr = default_conversion (expr);
7019
7020   if (warn_sequence_point)
7021     verify_sequence_points (expr);
7022
7023   if (TREE_TYPE (expr) != error_mark_node
7024       && !COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (expr))
7025       && TREE_CODE (TREE_TYPE (expr)) != ARRAY_TYPE)
7026     error ("expression statement has incomplete type");
7027
7028   /* If we're not processing a statement expression, warn about unused values.
7029      Warnings for statement expressions will be emitted later, once we figure
7030      out which is the result.  */
7031   if (!STATEMENT_LIST_STMT_EXPR (cur_stmt_list)
7032       && (extra_warnings || warn_unused_value))
7033     emit_side_effect_warnings (expr);
7034
7035   /* If the expression is not of a type to which we cannot assign a line
7036      number, wrap the thing in a no-op NOP_EXPR.  */
7037   if (DECL_P (expr) || CONSTANT_CLASS_P (expr))
7038     expr = build1 (NOP_EXPR, TREE_TYPE (expr), expr);
7039
7040   if (EXPR_P (expr))
7041     SET_EXPR_LOCATION (expr, input_location);
7042
7043   return expr;
7044 }
7045
7046 /* Emit an expression as a statement.  */
7047
7048 tree
7049 c_finish_expr_stmt (tree expr)
7050 {
7051   if (expr)
7052     return add_stmt (c_process_expr_stmt (expr));
7053   else
7054     return NULL;
7055 }
7056
7057 /* Do the opposite and emit a statement as an expression.  To begin,
7058    create a new binding level and return it.  */
7059
7060 tree
7061 c_begin_stmt_expr (void)
7062 {
7063   tree ret;
7064   struct c_label_context_se *nstack;
7065   struct c_label_list *glist;
7066
7067   /* We must force a BLOCK for this level so that, if it is not expanded
7068      later, there is a way to turn off the entire subtree of blocks that
7069      are contained in it.  */
7070   keep_next_level ();
7071   ret = c_begin_compound_stmt (true);
7072   if (c_switch_stack)
7073     {
7074       c_switch_stack->blocked_stmt_expr++;
7075       gcc_assert (c_switch_stack->blocked_stmt_expr != 0);
7076     }
7077   for (glist = label_context_stack_se->labels_used;
7078        glist != NULL;
7079        glist = glist->next)
7080     {
7081       C_DECL_UNDEFINABLE_STMT_EXPR (glist->label) = 1;
7082     }
7083   nstack = XOBNEW (&parser_obstack, struct c_label_context_se);
7084   nstack->labels_def = NULL;
7085   nstack->labels_used = NULL;
7086   nstack->next = label_context_stack_se;
7087   label_context_stack_se = nstack;
7088
7089   /* Mark the current statement list as belonging to a statement list.  */
7090   STATEMENT_LIST_STMT_EXPR (ret) = 1;
7091
7092   return ret;
7093 }
7094
7095 tree
7096 c_finish_stmt_expr (tree body)
7097 {
7098   tree last, type, tmp, val;
7099   tree *last_p;
7100   struct c_label_list *dlist, *glist, *glist_prev = NULL;
7101
7102   body = c_end_compound_stmt (body, true);
7103   if (c_switch_stack)
7104     {
7105       gcc_assert (c_switch_stack->blocked_stmt_expr != 0);
7106       c_switch_stack->blocked_stmt_expr--;
7107     }
7108   /* It is no longer possible to jump to labels defined within this
7109      statement expression.  */
7110   for (dlist = label_context_stack_se->labels_def;
7111        dlist != NULL;
7112        dlist = dlist->next)
7113     {
7114       C_DECL_UNJUMPABLE_STMT_EXPR (dlist->label) = 1;
7115     }
7116   /* It is again possible to define labels with a goto just outside
7117      this statement expression.  */
7118   for (glist = label_context_stack_se->next->labels_used;
7119        glist != NULL;
7120        glist = glist->next)
7121     {
7122       C_DECL_UNDEFINABLE_STMT_EXPR (glist->label) = 0;
7123       glist_prev = glist;
7124     }
7125   if (glist_prev != NULL)
7126     glist_prev->next = label_context_stack_se->labels_used;
7127   else
7128     label_context_stack_se->next->labels_used
7129       = label_context_stack_se->labels_used;
7130   label_context_stack_se = label_context_stack_se->next;
7131
7132   /* Locate the last statement in BODY.  See c_end_compound_stmt
7133      about always returning a BIND_EXPR.  */
7134   last_p = &BIND_EXPR_BODY (body);
7135   last = BIND_EXPR_BODY (body);
7136
7137  continue_searching:
7138   if (TREE_CODE (last) == STATEMENT_LIST)
7139     {
7140       tree_stmt_iterator i;
7141
7142       /* This can happen with degenerate cases like ({ }).  No value.  */
7143       if (!TREE_SIDE_EFFECTS (last))
7144         return body;
7145
7146       /* If we're supposed to generate side effects warnings, process
7147          all of the statements except the last.  */
7148       if (extra_warnings || warn_unused_value)
7149         {
7150           for (i = tsi_start (last); !tsi_one_before_end_p (i); tsi_next (&i))
7151             emit_side_effect_warnings (tsi_stmt (i));
7152         }
7153       else
7154         i = tsi_last (last);
7155       last_p = tsi_stmt_ptr (i);
7156       last = *last_p;
7157     }
7158
7159   /* If the end of the list is exception related, then the list was split
7160      by a call to push_cleanup.  Continue searching.  */
7161   if (TREE_CODE (last) == TRY_FINALLY_EXPR
7162       || TREE_CODE (last) == TRY_CATCH_EXPR)
7163     {
7164       last_p = &TREE_OPERAND (last, 0);
7165       last = *last_p;
7166       goto continue_searching;
7167     }
7168
7169   /* In the case that the BIND_EXPR is not necessary, return the
7170      expression out from inside it.  */
7171   if (last == error_mark_node
7172       || (last == BIND_EXPR_BODY (body)
7173           && BIND_EXPR_VARS (body) == NULL))
7174     return last;
7175
7176   /* Extract the type of said expression.  */
7177   type = TREE_TYPE (last);
7178
7179   /* If we're not returning a value at all, then the BIND_EXPR that
7180      we already have is a fine expression to return.  */
7181   if (!type || VOID_TYPE_P (type))
7182     return body;
7183
7184   /* Now that we've located the expression containing the value, it seems
7185      silly to make voidify_wrapper_expr repeat the process.  Create a
7186      temporary of the appropriate type and stick it in a TARGET_EXPR.  */
7187   tmp = create_tmp_var_raw (type, NULL);
7188
7189   /* Unwrap a no-op NOP_EXPR as added by c_finish_expr_stmt.  This avoids
7190      tree_expr_nonnegative_p giving up immediately.  */
7191   val = last;
7192   if (TREE_CODE (val) == NOP_EXPR
7193       && TREE_TYPE (val) == TREE_TYPE (TREE_OPERAND (val, 0)))
7194     val = TREE_OPERAND (val, 0);
7195
7196   *last_p = build2 (MODIFY_EXPR, void_type_node, tmp, val);
7197   SET_EXPR_LOCUS (*last_p, EXPR_LOCUS (last));
7198
7199   return build4 (TARGET_EXPR, type, tmp, body, NULL_TREE, NULL_TREE);
7200 }
7201
7202 /* Begin the scope of an identifier of variably modified type, scope
7203    number SCOPE.  Jumping from outside this scope to inside it is not
7204    permitted.  */
7205
7206 void
7207 c_begin_vm_scope (unsigned int scope)
7208 {
7209   struct c_label_context_vm *nstack;
7210   struct c_label_list *glist;
7211
7212   gcc_assert (scope > 0);
7213   if (c_switch_stack && !c_switch_stack->blocked_vm)
7214     c_switch_stack->blocked_vm = scope;
7215   for (glist = label_context_stack_vm->labels_used;
7216        glist != NULL;
7217        glist = glist->next)
7218     {
7219       C_DECL_UNDEFINABLE_VM (glist->label) = 1;
7220     }
7221   nstack = XOBNEW (&parser_obstack, struct c_label_context_vm);
7222   nstack->labels_def = NULL;
7223   nstack->labels_used = NULL;
7224   nstack->scope = scope;
7225   nstack->next = label_context_stack_vm;
7226   label_context_stack_vm = nstack;
7227 }
7228
7229 /* End a scope which may contain identifiers of variably modified
7230    type, scope number SCOPE.  */
7231
7232 void
7233 c_end_vm_scope (unsigned int scope)
7234 {
7235   if (label_context_stack_vm == NULL)
7236     return;
7237   if (c_switch_stack && c_switch_stack->blocked_vm == scope)
7238     c_switch_stack->blocked_vm = 0;
7239   /* We may have a number of nested scopes of identifiers with
7240      variably modified type, all at this depth.  Pop each in turn.  */
7241   while (label_context_stack_vm->scope == scope)
7242     {
7243       struct c_label_list *dlist, *glist, *glist_prev = NULL;
7244
7245       /* It is no longer possible to jump to labels defined within this
7246          scope.  */
7247       for (dlist = label_context_stack_vm->labels_def;
7248            dlist != NULL;
7249            dlist = dlist->next)
7250         {
7251           C_DECL_UNJUMPABLE_VM (dlist->label) = 1;
7252         }
7253       /* It is again possible to define labels with a goto just outside
7254          this scope.  */
7255       for (glist = label_context_stack_vm->next->labels_used;
7256            glist != NULL;
7257            glist = glist->next)
7258         {
7259           C_DECL_UNDEFINABLE_VM (glist->label) = 0;
7260           glist_prev = glist;
7261         }
7262       if (glist_prev != NULL)
7263         glist_prev->next = label_context_stack_vm->labels_used;
7264       else
7265         label_context_stack_vm->next->labels_used
7266           = label_context_stack_vm->labels_used;
7267       label_context_stack_vm = label_context_stack_vm->next;
7268     }
7269 }
7270 \f
7271 /* Begin and end compound statements.  This is as simple as pushing
7272    and popping new statement lists from the tree.  */
7273
7274 tree
7275 c_begin_compound_stmt (bool do_scope)
7276 {
7277   tree stmt = push_stmt_list ();
7278   if (do_scope)
7279     push_scope ();
7280   return stmt;
7281 }
7282
7283 tree
7284 c_end_compound_stmt (tree stmt, bool do_scope)
7285 {
7286   tree block = NULL;
7287
7288   if (do_scope)
7289     {
7290       if (c_dialect_objc ())
7291         objc_clear_super_receiver ();
7292       block = pop_scope ();
7293     }
7294
7295   stmt = pop_stmt_list (stmt);
7296   stmt = c_build_bind_expr (block, stmt);
7297
7298   /* If this compound statement is nested immediately inside a statement
7299      expression, then force a BIND_EXPR to be created.  Otherwise we'll
7300      do the wrong thing for ({ { 1; } }) or ({ 1; { } }).  In particular,
7301      STATEMENT_LISTs merge, and thus we can lose track of what statement
7302      was really last.  */
7303   if (cur_stmt_list
7304       && STATEMENT_LIST_STMT_EXPR (cur_stmt_list)
7305       && TREE_CODE (stmt) != BIND_EXPR)
7306     {
7307       stmt = build3 (BIND_EXPR, void_type_node, NULL, stmt, NULL);
7308       TREE_SIDE_EFFECTS (stmt) = 1;
7309     }
7310
7311   return stmt;
7312 }
7313
7314 /* Queue a cleanup.  CLEANUP is an expression/statement to be executed
7315    when the current scope is exited.  EH_ONLY is true when this is not
7316    meant to apply to normal control flow transfer.  */
7317
7318 void
7319 push_cleanup (tree ARG_UNUSED (decl), tree cleanup, bool eh_only)
7320 {
7321   enum tree_code code;
7322   tree stmt, list;
7323   bool stmt_expr;
7324
7325   code = eh_only ? TRY_CATCH_EXPR : TRY_FINALLY_EXPR;
7326   stmt = build_stmt (code, NULL, cleanup);
7327   add_stmt (stmt);
7328   stmt_expr = STATEMENT_LIST_STMT_EXPR (cur_stmt_list);
7329   list = push_stmt_list ();
7330   TREE_OPERAND (stmt, 0) = list;
7331   STATEMENT_LIST_STMT_EXPR (list) = stmt_expr;
7332 }
7333 \f
7334 /* Build a binary-operation expression without default conversions.
7335    CODE is the kind of expression to build.
7336    This function differs from `build' in several ways:
7337    the data type of the result is computed and recorded in it,
7338    warnings are generated if arg data types are invalid,
7339    special handling for addition and subtraction of pointers is known,
7340    and some optimization is done (operations on narrow ints
7341    are done in the narrower type when that gives the same result).
7342    Constant folding is also done before the result is returned.
7343
7344    Note that the operands will never have enumeral types, or function
7345    or array types, because either they will have the default conversions
7346    performed or they have both just been converted to some other type in which
7347    the arithmetic is to be done.  */
7348
7349 tree
7350 build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
7351                  int convert_p)
7352 {
7353   tree type0, type1;
7354   enum tree_code code0, code1;
7355   tree op0, op1;
7356
7357   /* Expression code to give to the expression when it is built.
7358      Normally this is CODE, which is what the caller asked for,
7359      but in some special cases we change it.  */
7360   enum tree_code resultcode = code;
7361
7362   /* Data type in which the computation is to be performed.
7363      In the simplest cases this is the common type of the arguments.  */
7364   tree result_type = NULL;
7365
7366   /* Nonzero means operands have already been type-converted
7367      in whatever way is necessary.
7368      Zero means they need to be converted to RESULT_TYPE.  */
7369   int converted = 0;
7370
7371   /* Nonzero means create the expression with this type, rather than
7372      RESULT_TYPE.  */
7373   tree build_type = 0;
7374
7375   /* Nonzero means after finally constructing the expression
7376      convert it to this type.  */
7377   tree final_type = 0;
7378
7379   /* Nonzero if this is an operation like MIN or MAX which can
7380      safely be computed in short if both args are promoted shorts.
7381      Also implies COMMON.
7382      -1 indicates a bitwise operation; this makes a difference
7383      in the exact conditions for when it is safe to do the operation
7384      in a narrower mode.  */
7385   int shorten = 0;
7386
7387   /* Nonzero if this is a comparison operation;
7388      if both args are promoted shorts, compare the original shorts.
7389      Also implies COMMON.  */
7390   int short_compare = 0;
7391
7392   /* Nonzero if this is a right-shift operation, which can be computed on the
7393      original short and then promoted if the operand is a promoted short.  */
7394   int short_shift = 0;
7395
7396   /* Nonzero means set RESULT_TYPE to the common type of the args.  */
7397   int common = 0;
7398
7399   if (convert_p)
7400     {
7401       op0 = default_conversion (orig_op0);
7402       op1 = default_conversion (orig_op1);
7403     }
7404   else
7405     {
7406       op0 = orig_op0;
7407       op1 = orig_op1;
7408     }
7409
7410   type0 = TREE_TYPE (op0);
7411   type1 = TREE_TYPE (op1);
7412
7413   /* The expression codes of the data types of the arguments tell us
7414      whether the arguments are integers, floating, pointers, etc.  */
7415   code0 = TREE_CODE (type0);
7416   code1 = TREE_CODE (type1);
7417
7418   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
7419   STRIP_TYPE_NOPS (op0);
7420   STRIP_TYPE_NOPS (op1);
7421
7422   /* If an error was already reported for one of the arguments,
7423      avoid reporting another error.  */
7424
7425   if (code0 == ERROR_MARK || code1 == ERROR_MARK)
7426     return error_mark_node;
7427
7428   switch (code)
7429     {
7430     case PLUS_EXPR:
7431       /* Handle the pointer + int case.  */
7432       if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7433         return pointer_int_sum (PLUS_EXPR, op0, op1);
7434       else if (code1 == POINTER_TYPE && code0 == INTEGER_TYPE)
7435         return pointer_int_sum (PLUS_EXPR, op1, op0);
7436       else
7437         common = 1;
7438       break;
7439
7440     case MINUS_EXPR:
7441       /* Subtraction of two similar pointers.
7442          We must subtract them as integers, then divide by object size.  */
7443       if (code0 == POINTER_TYPE && code1 == POINTER_TYPE
7444           && comp_target_types (type0, type1, 1))
7445         return pointer_diff (op0, op1);
7446       /* Handle pointer minus int.  Just like pointer plus int.  */
7447       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7448         return pointer_int_sum (MINUS_EXPR, op0, op1);
7449       else
7450         common = 1;
7451       break;
7452
7453     case MULT_EXPR:
7454       common = 1;
7455       break;
7456
7457     case TRUNC_DIV_EXPR:
7458     case CEIL_DIV_EXPR:
7459     case FLOOR_DIV_EXPR:
7460     case ROUND_DIV_EXPR:
7461     case EXACT_DIV_EXPR:
7462       /* Floating point division by zero is a legitimate way to obtain
7463          infinities and NaNs.  */
7464       if (warn_div_by_zero && skip_evaluation == 0 && integer_zerop (op1))
7465         warning (0, "division by zero");
7466
7467       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
7468            || code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
7469           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
7470               || code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE))
7471         {
7472           if (code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
7473             code0 = TREE_CODE (TREE_TYPE (TREE_TYPE (op0)));
7474           if (code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE)
7475             code1 = TREE_CODE (TREE_TYPE (TREE_TYPE (op1)));
7476
7477           if (!(code0 == INTEGER_TYPE && code1 == INTEGER_TYPE))
7478             resultcode = RDIV_EXPR;
7479           else
7480             /* Although it would be tempting to shorten always here, that
7481                loses on some targets, since the modulo instruction is
7482                undefined if the quotient can't be represented in the
7483                computation mode.  We shorten only if unsigned or if
7484                dividing by something we know != -1.  */
7485             shorten = (TYPE_UNSIGNED (TREE_TYPE (orig_op0))
7486                        || (TREE_CODE (op1) == INTEGER_CST
7487                            && !integer_all_onesp (op1)));
7488           common = 1;
7489         }
7490       break;
7491
7492     case BIT_AND_EXPR:
7493     case BIT_IOR_EXPR:
7494     case BIT_XOR_EXPR:
7495       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7496         shorten = -1;
7497       else if (code0 == VECTOR_TYPE && code1 == VECTOR_TYPE)
7498         common = 1;
7499       break;
7500
7501     case TRUNC_MOD_EXPR:
7502     case FLOOR_MOD_EXPR:
7503       if (warn_div_by_zero && skip_evaluation == 0 && integer_zerop (op1))
7504         warning (0, "division by zero");
7505
7506       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7507         {
7508           /* Although it would be tempting to shorten always here, that loses
7509              on some targets, since the modulo instruction is undefined if the
7510              quotient can't be represented in the computation mode.  We shorten
7511              only if unsigned or if dividing by something we know != -1.  */
7512           shorten = (TYPE_UNSIGNED (TREE_TYPE (orig_op0))
7513                      || (TREE_CODE (op1) == INTEGER_CST
7514                          && !integer_all_onesp (op1)));
7515           common = 1;
7516         }
7517       break;
7518
7519     case TRUTH_ANDIF_EXPR:
7520     case TRUTH_ORIF_EXPR:
7521     case TRUTH_AND_EXPR:
7522     case TRUTH_OR_EXPR:
7523     case TRUTH_XOR_EXPR:
7524       if ((code0 == INTEGER_TYPE || code0 == POINTER_TYPE
7525            || code0 == REAL_TYPE || code0 == COMPLEX_TYPE)
7526           && (code1 == INTEGER_TYPE || code1 == POINTER_TYPE
7527               || code1 == REAL_TYPE || code1 == COMPLEX_TYPE))
7528         {
7529           /* Result of these operations is always an int,
7530              but that does not mean the operands should be
7531              converted to ints!  */
7532           result_type = integer_type_node;
7533           op0 = c_common_truthvalue_conversion (op0);
7534           op1 = c_common_truthvalue_conversion (op1);
7535           converted = 1;
7536         }
7537       break;
7538
7539       /* Shift operations: result has same type as first operand;
7540          always convert second operand to int.
7541          Also set SHORT_SHIFT if shifting rightward.  */
7542
7543     case RSHIFT_EXPR:
7544       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7545         {
7546           if (TREE_CODE (op1) == INTEGER_CST && skip_evaluation == 0)
7547             {
7548               if (tree_int_cst_sgn (op1) < 0)
7549                 warning (0, "right shift count is negative");
7550               else
7551                 {
7552                   if (!integer_zerop (op1))
7553                     short_shift = 1;
7554
7555                   if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
7556                     warning (0, "right shift count >= width of type");
7557                 }
7558             }
7559
7560           /* Use the type of the value to be shifted.  */
7561           result_type = type0;
7562           /* Convert the shift-count to an integer, regardless of size
7563              of value being shifted.  */
7564           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
7565             op1 = convert (integer_type_node, op1);
7566           /* Avoid converting op1 to result_type later.  */
7567           converted = 1;
7568         }
7569       break;
7570
7571     case LSHIFT_EXPR:
7572       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7573         {
7574           if (TREE_CODE (op1) == INTEGER_CST && skip_evaluation == 0)
7575             {
7576               if (tree_int_cst_sgn (op1) < 0)
7577                 warning (0, "left shift count is negative");
7578
7579               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
7580                 warning (0, "left shift count >= width of type");
7581             }
7582
7583           /* Use the type of the value to be shifted.  */
7584           result_type = type0;
7585           /* Convert the shift-count to an integer, regardless of size
7586              of value being shifted.  */
7587           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
7588             op1 = convert (integer_type_node, op1);
7589           /* Avoid converting op1 to result_type later.  */
7590           converted = 1;
7591         }
7592       break;
7593
7594     case EQ_EXPR:
7595     case NE_EXPR:
7596       if (warn_float_equal && (code0 == REAL_TYPE || code1 == REAL_TYPE))
7597         warning (0, "comparing floating point with == or != is unsafe");
7598       /* Result of comparison is always int,
7599          but don't convert the args to int!  */
7600       build_type = integer_type_node;
7601       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
7602            || code0 == COMPLEX_TYPE)
7603           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
7604               || code1 == COMPLEX_TYPE))
7605         short_compare = 1;
7606       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
7607         {
7608           tree tt0 = TREE_TYPE (type0);
7609           tree tt1 = TREE_TYPE (type1);
7610           /* Anything compares with void *.  void * compares with anything.
7611              Otherwise, the targets must be compatible
7612              and both must be object or both incomplete.  */
7613           if (comp_target_types (type0, type1, 1))
7614             result_type = common_pointer_type (type0, type1);
7615           else if (VOID_TYPE_P (tt0))
7616             {
7617               /* op0 != orig_op0 detects the case of something
7618                  whose value is 0 but which isn't a valid null ptr const.  */
7619               if (pedantic && (!integer_zerop (op0) || op0 != orig_op0)
7620                   && TREE_CODE (tt1) == FUNCTION_TYPE)
7621                 pedwarn ("ISO C forbids comparison of %<void *%>"
7622                          " with function pointer");
7623             }
7624           else if (VOID_TYPE_P (tt1))
7625             {
7626               if (pedantic && (!integer_zerop (op1) || op1 != orig_op1)
7627                   && TREE_CODE (tt0) == FUNCTION_TYPE)
7628                 pedwarn ("ISO C forbids comparison of %<void *%>"
7629                          " with function pointer");
7630             }
7631           else
7632             pedwarn ("comparison of distinct pointer types lacks a cast");
7633
7634           if (result_type == NULL_TREE)
7635             result_type = ptr_type_node;
7636         }
7637       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
7638                && integer_zerop (op1))
7639         result_type = type0;
7640       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
7641                && integer_zerop (op0))
7642         result_type = type1;
7643       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7644         {
7645           result_type = type0;
7646           pedwarn ("comparison between pointer and integer");
7647         }
7648       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
7649         {
7650           result_type = type1;
7651           pedwarn ("comparison between pointer and integer");
7652         }
7653       break;
7654
7655     case LE_EXPR:
7656     case GE_EXPR:
7657     case LT_EXPR:
7658     case GT_EXPR:
7659       build_type = integer_type_node;
7660       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
7661           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
7662         short_compare = 1;
7663       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
7664         {
7665           if (comp_target_types (type0, type1, 1))
7666             {
7667               result_type = common_pointer_type (type0, type1);
7668               if (!COMPLETE_TYPE_P (TREE_TYPE (type0))
7669                   != !COMPLETE_TYPE_P (TREE_TYPE (type1)))
7670                 pedwarn ("comparison of complete and incomplete pointers");
7671               else if (pedantic
7672                        && TREE_CODE (TREE_TYPE (type0)) == FUNCTION_TYPE)
7673                 pedwarn ("ISO C forbids ordered comparisons of pointers to functions");
7674             }
7675           else
7676             {
7677               result_type = ptr_type_node;
7678               pedwarn ("comparison of distinct pointer types lacks a cast");
7679             }
7680         }
7681       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
7682                && integer_zerop (op1))
7683         {
7684           result_type = type0;
7685           if (pedantic || extra_warnings)
7686             pedwarn ("ordered comparison of pointer with integer zero");
7687         }
7688       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
7689                && integer_zerop (op0))
7690         {
7691           result_type = type1;
7692           if (pedantic)
7693             pedwarn ("ordered comparison of pointer with integer zero");
7694         }
7695       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7696         {
7697           result_type = type0;
7698           pedwarn ("comparison between pointer and integer");
7699         }
7700       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
7701         {
7702           result_type = type1;
7703           pedwarn ("comparison between pointer and integer");
7704         }
7705       break;
7706
7707     default:
7708       gcc_unreachable ();
7709     }
7710
7711   if (code0 == ERROR_MARK || code1 == ERROR_MARK)
7712     return error_mark_node;
7713
7714   if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE || code0 == COMPLEX_TYPE
7715        || code0 == VECTOR_TYPE)
7716       &&
7717       (code1 == INTEGER_TYPE || code1 == REAL_TYPE || code1 == COMPLEX_TYPE
7718        || code1 == VECTOR_TYPE))
7719     {
7720       int none_complex = (code0 != COMPLEX_TYPE && code1 != COMPLEX_TYPE);
7721
7722       if (shorten || common || short_compare)
7723         result_type = c_common_type (type0, type1);
7724
7725       /* For certain operations (which identify themselves by shorten != 0)
7726          if both args were extended from the same smaller type,
7727          do the arithmetic in that type and then extend.
7728
7729          shorten !=0 and !=1 indicates a bitwise operation.
7730          For them, this optimization is safe only if
7731          both args are zero-extended or both are sign-extended.
7732          Otherwise, we might change the result.
7733          Eg, (short)-1 | (unsigned short)-1 is (int)-1
7734          but calculated in (unsigned short) it would be (unsigned short)-1.  */
7735
7736       if (shorten && none_complex)
7737         {
7738           int unsigned0, unsigned1;
7739           tree arg0 = get_narrower (op0, &unsigned0);
7740           tree arg1 = get_narrower (op1, &unsigned1);
7741           /* UNS is 1 if the operation to be done is an unsigned one.  */
7742           int uns = TYPE_UNSIGNED (result_type);
7743           tree type;
7744
7745           final_type = result_type;
7746
7747           /* Handle the case that OP0 (or OP1) does not *contain* a conversion
7748              but it *requires* conversion to FINAL_TYPE.  */
7749
7750           if ((TYPE_PRECISION (TREE_TYPE (op0))
7751                == TYPE_PRECISION (TREE_TYPE (arg0)))
7752               && TREE_TYPE (op0) != final_type)
7753             unsigned0 = TYPE_UNSIGNED (TREE_TYPE (op0));
7754           if ((TYPE_PRECISION (TREE_TYPE (op1))
7755                == TYPE_PRECISION (TREE_TYPE (arg1)))
7756               && TREE_TYPE (op1) != final_type)
7757             unsigned1 = TYPE_UNSIGNED (TREE_TYPE (op1));
7758
7759           /* Now UNSIGNED0 is 1 if ARG0 zero-extends to FINAL_TYPE.  */
7760
7761           /* For bitwise operations, signedness of nominal type
7762              does not matter.  Consider only how operands were extended.  */
7763           if (shorten == -1)
7764             uns = unsigned0;
7765
7766           /* Note that in all three cases below we refrain from optimizing
7767              an unsigned operation on sign-extended args.
7768              That would not be valid.  */
7769
7770           /* Both args variable: if both extended in same way
7771              from same width, do it in that width.
7772              Do it unsigned if args were zero-extended.  */
7773           if ((TYPE_PRECISION (TREE_TYPE (arg0))
7774                < TYPE_PRECISION (result_type))
7775               && (TYPE_PRECISION (TREE_TYPE (arg1))
7776                   == TYPE_PRECISION (TREE_TYPE (arg0)))
7777               && unsigned0 == unsigned1
7778               && (unsigned0 || !uns))
7779             result_type
7780               = c_common_signed_or_unsigned_type
7781               (unsigned0, c_common_type (TREE_TYPE (arg0), TREE_TYPE (arg1)));
7782           else if (TREE_CODE (arg0) == INTEGER_CST
7783                    && (unsigned1 || !uns)
7784                    && (TYPE_PRECISION (TREE_TYPE (arg1))
7785                        < TYPE_PRECISION (result_type))
7786                    && (type
7787                        = c_common_signed_or_unsigned_type (unsigned1,
7788                                                            TREE_TYPE (arg1)),
7789                        int_fits_type_p (arg0, type)))
7790             result_type = type;
7791           else if (TREE_CODE (arg1) == INTEGER_CST
7792                    && (unsigned0 || !uns)
7793                    && (TYPE_PRECISION (TREE_TYPE (arg0))
7794                        < TYPE_PRECISION (result_type))
7795                    && (type
7796                        = c_common_signed_or_unsigned_type (unsigned0,
7797                                                            TREE_TYPE (arg0)),
7798                        int_fits_type_p (arg1, type)))
7799             result_type = type;
7800         }
7801
7802       /* Shifts can be shortened if shifting right.  */
7803
7804       if (short_shift)
7805         {
7806           int unsigned_arg;
7807           tree arg0 = get_narrower (op0, &unsigned_arg);
7808
7809           final_type = result_type;
7810
7811           if (arg0 == op0 && final_type == TREE_TYPE (op0))
7812             unsigned_arg = TYPE_UNSIGNED (TREE_TYPE (op0));
7813
7814           if (TYPE_PRECISION (TREE_TYPE (arg0)) < TYPE_PRECISION (result_type)
7815               /* We can shorten only if the shift count is less than the
7816                  number of bits in the smaller type size.  */
7817               && compare_tree_int (op1, TYPE_PRECISION (TREE_TYPE (arg0))) < 0
7818               /* We cannot drop an unsigned shift after sign-extension.  */
7819               && (!TYPE_UNSIGNED (final_type) || unsigned_arg))
7820             {
7821               /* Do an unsigned shift if the operand was zero-extended.  */
7822               result_type
7823                 = c_common_signed_or_unsigned_type (unsigned_arg,
7824                                                     TREE_TYPE (arg0));
7825               /* Convert value-to-be-shifted to that type.  */
7826               if (TREE_TYPE (op0) != result_type)
7827                 op0 = convert (result_type, op0);
7828               converted = 1;
7829             }
7830         }
7831
7832       /* Comparison operations are shortened too but differently.
7833          They identify themselves by setting short_compare = 1.  */
7834
7835       if (short_compare)
7836         {
7837           /* Don't write &op0, etc., because that would prevent op0
7838              from being kept in a register.
7839              Instead, make copies of the our local variables and
7840              pass the copies by reference, then copy them back afterward.  */
7841           tree xop0 = op0, xop1 = op1, xresult_type = result_type;
7842           enum tree_code xresultcode = resultcode;
7843           tree val
7844             = shorten_compare (&xop0, &xop1, &xresult_type, &xresultcode);
7845
7846           if (val != 0)
7847             return val;
7848
7849           op0 = xop0, op1 = xop1;
7850           converted = 1;
7851           resultcode = xresultcode;
7852
7853           if (warn_sign_compare && skip_evaluation == 0)
7854             {
7855               int op0_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op0));
7856               int op1_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op1));
7857               int unsignedp0, unsignedp1;
7858               tree primop0 = get_narrower (op0, &unsignedp0);
7859               tree primop1 = get_narrower (op1, &unsignedp1);
7860
7861               xop0 = orig_op0;
7862               xop1 = orig_op1;
7863               STRIP_TYPE_NOPS (xop0);
7864               STRIP_TYPE_NOPS (xop1);
7865
7866               /* Give warnings for comparisons between signed and unsigned
7867                  quantities that may fail.
7868
7869                  Do the checking based on the original operand trees, so that
7870                  casts will be considered, but default promotions won't be.
7871
7872                  Do not warn if the comparison is being done in a signed type,
7873                  since the signed type will only be chosen if it can represent
7874                  all the values of the unsigned type.  */
7875               if (!TYPE_UNSIGNED (result_type))
7876                 /* OK */;
7877               /* Do not warn if both operands are the same signedness.  */
7878               else if (op0_signed == op1_signed)
7879                 /* OK */;
7880               else
7881                 {
7882                   tree sop, uop;
7883
7884                   if (op0_signed)
7885                     sop = xop0, uop = xop1;
7886                   else
7887                     sop = xop1, uop = xop0;
7888
7889                   /* Do not warn if the signed quantity is an
7890                      unsuffixed integer literal (or some static
7891                      constant expression involving such literals or a
7892                      conditional expression involving such literals)
7893                      and it is non-negative.  */
7894                   if (tree_expr_nonnegative_p (sop))
7895                     /* OK */;
7896                   /* Do not warn if the comparison is an equality operation,
7897                      the unsigned quantity is an integral constant, and it
7898                      would fit in the result if the result were signed.  */
7899                   else if (TREE_CODE (uop) == INTEGER_CST
7900                            && (resultcode == EQ_EXPR || resultcode == NE_EXPR)
7901                            && int_fits_type_p
7902                            (uop, c_common_signed_type (result_type)))
7903                     /* OK */;
7904                   /* Do not warn if the unsigned quantity is an enumeration
7905                      constant and its maximum value would fit in the result
7906                      if the result were signed.  */
7907                   else if (TREE_CODE (uop) == INTEGER_CST
7908                            && TREE_CODE (TREE_TYPE (uop)) == ENUMERAL_TYPE
7909                            && int_fits_type_p
7910                            (TYPE_MAX_VALUE (TREE_TYPE (uop)),
7911                             c_common_signed_type (result_type)))
7912                     /* OK */;
7913                   else
7914                     warning (0, "comparison between signed and unsigned");
7915                 }
7916
7917               /* Warn if two unsigned values are being compared in a size
7918                  larger than their original size, and one (and only one) is the
7919                  result of a `~' operator.  This comparison will always fail.
7920
7921                  Also warn if one operand is a constant, and the constant
7922                  does not have all bits set that are set in the ~ operand
7923                  when it is extended.  */
7924
7925               if ((TREE_CODE (primop0) == BIT_NOT_EXPR)
7926                   != (TREE_CODE (primop1) == BIT_NOT_EXPR))
7927                 {
7928                   if (TREE_CODE (primop0) == BIT_NOT_EXPR)
7929                     primop0 = get_narrower (TREE_OPERAND (primop0, 0),
7930                                             &unsignedp0);
7931                   else
7932                     primop1 = get_narrower (TREE_OPERAND (primop1, 0),
7933                                             &unsignedp1);
7934
7935                   if (host_integerp (primop0, 0) || host_integerp (primop1, 0))
7936                     {
7937                       tree primop;
7938                       HOST_WIDE_INT constant, mask;
7939                       int unsignedp, bits;
7940
7941                       if (host_integerp (primop0, 0))
7942                         {
7943                           primop = primop1;
7944                           unsignedp = unsignedp1;
7945                           constant = tree_low_cst (primop0, 0);
7946                         }
7947                       else
7948                         {
7949                           primop = primop0;
7950                           unsignedp = unsignedp0;
7951                           constant = tree_low_cst (primop1, 0);
7952                         }
7953
7954                       bits = TYPE_PRECISION (TREE_TYPE (primop));
7955                       if (bits < TYPE_PRECISION (result_type)
7956                           && bits < HOST_BITS_PER_WIDE_INT && unsignedp)
7957                         {
7958                           mask = (~(HOST_WIDE_INT) 0) << bits;
7959                           if ((mask & constant) != mask)
7960                             warning (0, "comparison of promoted ~unsigned with constant");
7961                         }
7962                     }
7963                   else if (unsignedp0 && unsignedp1
7964                            && (TYPE_PRECISION (TREE_TYPE (primop0))
7965                                < TYPE_PRECISION (result_type))
7966                            && (TYPE_PRECISION (TREE_TYPE (primop1))
7967                                < TYPE_PRECISION (result_type)))
7968                     warning (0, "comparison of promoted ~unsigned with unsigned");
7969                 }
7970             }
7971         }
7972     }
7973
7974   /* At this point, RESULT_TYPE must be nonzero to avoid an error message.
7975      If CONVERTED is zero, both args will be converted to type RESULT_TYPE.
7976      Then the expression will be built.
7977      It will be given type FINAL_TYPE if that is nonzero;
7978      otherwise, it will be given type RESULT_TYPE.  */
7979
7980   if (!result_type)
7981     {
7982       binary_op_error (code);
7983       return error_mark_node;
7984     }
7985
7986   if (!converted)
7987     {
7988       if (TREE_TYPE (op0) != result_type)
7989         op0 = convert (result_type, op0);
7990       if (TREE_TYPE (op1) != result_type)
7991         op1 = convert (result_type, op1);
7992
7993       /* This can happen if one operand has a vector type, and the other
7994          has a different type.  */
7995       if (TREE_CODE (op0) == ERROR_MARK || TREE_CODE (op1) == ERROR_MARK)
7996         return error_mark_node;
7997     }
7998
7999   if (build_type == NULL_TREE)
8000     build_type = result_type;
8001
8002   {
8003     tree result = build2 (resultcode, build_type, op0, op1);
8004
8005     /* Treat expressions in initializers specially as they can't trap.  */
8006     result = require_constant_value ? fold_initializer (result)
8007                                     : fold (result);
8008
8009     if (final_type != 0)
8010       result = convert (final_type, result);
8011     return result;
8012   }
8013 }
8014
8015
8016 /* Convert EXPR to be a truth-value, validating its type for this
8017    purpose.  Passes EXPR to default_function_array_conversion.  */
8018
8019 tree
8020 c_objc_common_truthvalue_conversion (tree expr)
8021 {
8022   expr = default_function_array_conversion (expr);
8023   switch (TREE_CODE (TREE_TYPE (expr)))
8024     {
8025     case ARRAY_TYPE:
8026       error ("used array that cannot be converted to pointer where scalar is required");
8027       return error_mark_node;
8028
8029     case RECORD_TYPE:
8030       error ("used struct type value where scalar is required");
8031       return error_mark_node;
8032
8033     case UNION_TYPE:
8034       error ("used union type value where scalar is required");
8035       return error_mark_node;
8036
8037     default:
8038       break;
8039     }
8040
8041   /* ??? Should we also give an error for void and vectors rather than
8042      leaving those to give errors later?  */
8043   return c_common_truthvalue_conversion (expr);
8044 }