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, 51 Franklin Street, Fifth Floor, Boston, MA
  20 02110-1301, 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);
  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 lookup_field (tree, tree);
  84 static tree convert_arguments (tree, tree, tree, tree);
  85 static tree pointer_diff (tree, tree);
  86 static tree convert_for_assignment (tree, tree, enum impl_conv, tree, tree,
  87                                     int);
  88 static tree valid_compound_expr_initializer (tree, tree);
  89 static void push_string (const char *);
  90 static void push_member_name (tree);
  91 static void push_array_bounds (int);
  92 static int spelling_length (void);
  93 static char *print_spelling (char *);
  94 static void warning_init (const char *);
  95 static tree digest_init (tree, tree, bool, int);
  96 static void output_init_element (tree, bool, tree, tree, int);
  97 static void output_pending_init_elements (int);
  98 static int set_designator (int);
  99 static void push_range_stack (tree);
 100 static void add_pending_init (tree, tree);
 101 static void set_nonincremental_init (void);
 102 static void set_nonincremental_init_from_string (tree);
 103 static tree find_init_member (tree);
 104 static void readonly_error (tree, enum lvalue_use);
 105 static int lvalue_or_else (tree, enum lvalue_use);
 106 static int lvalue_p (tree);
 107 static void record_maybe_used_decl (tree);
 108 \f
 109 /* Do `exp = require_complete_type (exp);' to make sure exp
 110    does not have an incomplete type.  (That includes void types.)  */
 111
 112 tree
 113 require_complete_type (tree value)
 114 {
 115   tree type = TREE_TYPE (value);
 116
 117   if (value == error_mark_node || type == error_mark_node)
 118     return error_mark_node;
 119
 120   /* First, detect a valid value with a complete type.  */
 121   if (COMPLETE_TYPE_P (type))
 122     return value;
 123
 124   c_incomplete_type_error (value, type);
 125   return error_mark_node;
 126 }
 127
 128 /* Print an error message for invalid use of an incomplete type.
 129    VALUE is the expression that was used (or 0 if that isn't known)
 130    and TYPE is the type that was invalid.  */
 131
 132 void
 133 c_incomplete_type_error (tree value, tree type)
 134 {
 135   const char *type_code_string;
 136
 137   /* Avoid duplicate error message.  */
 138   if (TREE_CODE (type) == ERROR_MARK)
 139     return;
 140
 141   if (value != 0 && (TREE_CODE (value) == VAR_DECL
 142                      || TREE_CODE (value) == PARM_DECL))
 143     error ("%qD has an incomplete type", value);
 144   else
 145     {
 146     retry:
 147       /* We must print an error message.  Be clever about what it says.  */
 148
 149       switch (TREE_CODE (type))
 150         {
 151         case RECORD_TYPE:
 152           type_code_string = "struct";
 153           break;
 154
 155         case UNION_TYPE:
 156           type_code_string = "union";
 157           break;
 158
 159         case ENUMERAL_TYPE:
 160           type_code_string = "enum";
 161           break;
 162
 163         case VOID_TYPE:
 164           error ("invalid use of void expression");
 165           return;
 166
 167         case ARRAY_TYPE:
 168           if (TYPE_DOMAIN (type))
 169             {
 170               if (TYPE_MAX_VALUE (TYPE_DOMAIN (type)) == NULL)
 171                 {
 172                   error ("invalid use of flexible array member");
 173                   return;
 174                 }
 175               type = TREE_TYPE (type);
 176               goto retry;
 177             }
 178           error ("invalid use of array with unspecified bounds");
 179           return;
 180
 181         default:
 182           gcc_unreachable ();
 183         }
 184
 185       if (TREE_CODE (TYPE_NAME (type)) == IDENTIFIER_NODE)
 186         error ("invalid use of undefined type %<%s %E%>",
 187                type_code_string, TYPE_NAME (type));
 188       else
 189         /* If this type has a typedef-name, the TYPE_NAME is a TYPE_DECL.  */
 190         error ("invalid use of incomplete typedef %qD", TYPE_NAME (type));
 191     }
 192 }
 193
 194 /* Given a type, apply default promotions wrt unnamed function
 195    arguments and return the new type.  */
 196
 197 tree
 198 c_type_promotes_to (tree type)
 199 {
 200   if (TYPE_MAIN_VARIANT (type) == float_type_node)
 201     return double_type_node;
 202
 203   if (c_promoting_integer_type_p (type))
 204     {
 205       /* Preserve unsignedness if not really getting any wider.  */
 206       if (TYPE_UNSIGNED (type)
 207           && (TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node)))
 208         return unsigned_type_node;
 209       return integer_type_node;
 210     }
 211
 212   return type;
 213 }
 214
 215 /* Return a variant of TYPE which has all the type qualifiers of LIKE
 216    as well as those of TYPE.  */
 217
 218 static tree
 219 qualify_type (tree type, tree like)
 220 {
 221   return c_build_qualified_type (type,
 222                                  TYPE_QUALS (type) | TYPE_QUALS (like));
 223 }
 224 \f
 225 /* Return the composite type of two compatible types.
 226
 227    We assume that comptypes has already been done and returned
 228    nonzero; if that isn't so, this may crash.  In particular, we
 229    assume that qualifiers match.  */
 230
 231 tree
 232 composite_type (tree t1, tree t2)
 233 {
 234   enum tree_code code1;
 235   enum tree_code code2;
 236   tree attributes;
 237
 238   /* Save time if the two types are the same.  */
 239
 240   if (t1 == t2) return t1;
 241
 242   /* If one type is nonsense, use the other.  */
 243   if (t1 == error_mark_node)
 244     return t2;
 245   if (t2 == error_mark_node)
 246     return t1;
 247
 248   code1 = TREE_CODE (t1);
 249   code2 = TREE_CODE (t2);
 250
 251   /* Merge the attributes.  */
 252   attributes = targetm.merge_type_attributes (t1, t2);
 253
 254   /* If one is an enumerated type and the other is the compatible
 255      integer type, the composite type might be either of the two
 256      (DR#013 question 3).  For consistency, use the enumerated type as
 257      the composite type.  */
 258
 259   if (code1 == ENUMERAL_TYPE && code2 == INTEGER_TYPE)
 260     return t1;
 261   if (code2 == ENUMERAL_TYPE && code1 == INTEGER_TYPE)
 262     return t2;
 263
 264   gcc_assert (code1 == code2);
 265
 266   switch (code1)
 267     {
 268     case POINTER_TYPE:
 269       /* For two pointers, do this recursively on the target type.  */
 270       {
 271         tree pointed_to_1 = TREE_TYPE (t1);
 272         tree pointed_to_2 = TREE_TYPE (t2);
 273         tree target = composite_type (pointed_to_1, pointed_to_2);
 274         t1 = build_pointer_type (target);
 275         t1 = build_type_attribute_variant (t1, attributes);
 276         return qualify_type (t1, t2);
 277       }
 278
 279     case ARRAY_TYPE:
 280       {
 281         tree elt = composite_type (TREE_TYPE (t1), TREE_TYPE (t2));
 282         int quals;
 283         tree unqual_elt;
 284
 285         /* We should not have any type quals on arrays at all.  */
 286         gcc_assert (!TYPE_QUALS (t1) && !TYPE_QUALS (t2));
 287
 288         /* Save space: see if the result is identical to one of the args.  */
 289         if (elt == TREE_TYPE (t1) && TYPE_DOMAIN (t1))
 290           return build_type_attribute_variant (t1, attributes);
 291         if (elt == TREE_TYPE (t2) && TYPE_DOMAIN (t2))
 292           return build_type_attribute_variant (t2, attributes);
 293
 294         if (elt == TREE_TYPE (t1) && !TYPE_DOMAIN (t2) && !TYPE_DOMAIN (t1))
 295           return build_type_attribute_variant (t1, attributes);
 296         if (elt == TREE_TYPE (t2) && !TYPE_DOMAIN (t2) && !TYPE_DOMAIN (t1))
 297           return build_type_attribute_variant (t2, attributes);
 298
 299         /* Merge the element types, and have a size if either arg has
 300            one.  We may have qualifiers on the element types.  To set
 301            up TYPE_MAIN_VARIANT correctly, we need to form the
 302            composite of the unqualified types and add the qualifiers
 303            back at the end.  */
 304         quals = TYPE_QUALS (strip_array_types (elt));
 305         unqual_elt = c_build_qualified_type (elt, TYPE_UNQUALIFIED);
 306         t1 = build_array_type (unqual_elt,
 307                                TYPE_DOMAIN (TYPE_DOMAIN (t1) ? t1 : t2));
 308         t1 = c_build_qualified_type (t1, quals);
 309         return build_type_attribute_variant (t1, attributes);
 310       }
 311
 312     case FUNCTION_TYPE:
 313       /* Function types: prefer the one that specified arg types.
 314          If both do, merge the arg types.  Also merge the return types.  */
 315       {
 316         tree valtype = composite_type (TREE_TYPE (t1), TREE_TYPE (t2));
 317         tree p1 = TYPE_ARG_TYPES (t1);
 318         tree p2 = TYPE_ARG_TYPES (t2);
 319         int len;
 320         tree newargs, n;
 321         int i;
 322
 323         /* Save space: see if the result is identical to one of the args.  */
 324         if (valtype == TREE_TYPE (t1) && !TYPE_ARG_TYPES (t2))
 325           return build_type_attribute_variant (t1, attributes);
 326         if (valtype == TREE_TYPE (t2) && !TYPE_ARG_TYPES (t1))
 327           return build_type_attribute_variant (t2, attributes);
 328
 329         /* Simple way if one arg fails to specify argument types.  */
 330         if (TYPE_ARG_TYPES (t1) == 0)
 331          {
 332             t1 = build_function_type (valtype, TYPE_ARG_TYPES (t2));
 333             t1 = build_type_attribute_variant (t1, attributes);
 334             return qualify_type (t1, t2);
 335          }
 336         if (TYPE_ARG_TYPES (t2) == 0)
 337          {
 338            t1 = build_function_type (valtype, TYPE_ARG_TYPES (t1));
 339            t1 = build_type_attribute_variant (t1, attributes);
 340            return qualify_type (t1, t2);
 341          }
 342
 343         /* If both args specify argument types, we must merge the two
 344            lists, argument by argument.  */
 345         /* Tell global_bindings_p to return false so that variable_size
 346            doesn't die on VLAs in parameter types.  */
 347         c_override_global_bindings_to_false = true;
 348
 349         len = list_length (p1);
 350         newargs = 0;
 351
 352         for (i = 0; i < len; i++)
 353           newargs = tree_cons (NULL_TREE, NULL_TREE, newargs);
 354
 355         n = newargs;
 356
 357         for (; p1;
 358              p1 = TREE_CHAIN (p1), p2 = TREE_CHAIN (p2), n = TREE_CHAIN (n))
 359           {
 360             /* A null type means arg type is not specified.
 361                Take whatever the other function type has.  */
 362             if (TREE_VALUE (p1) == 0)
 363               {
 364                 TREE_VALUE (n) = TREE_VALUE (p2);
 365                 goto parm_done;
 366               }
 367             if (TREE_VALUE (p2) == 0)
 368               {
 369                 TREE_VALUE (n) = TREE_VALUE (p1);
 370                 goto parm_done;
 371               }
 372
 373             /* Given  wait (union {union wait *u; int *i} *)
 374                and  wait (union wait *),
 375                prefer  union wait *  as type of parm.  */
 376             if (TREE_CODE (TREE_VALUE (p1)) == UNION_TYPE
 377                 && TREE_VALUE (p1) != TREE_VALUE (p2))
 378               {
 379                 tree memb;
 380                 tree mv2 = TREE_VALUE (p2);
 381                 if (mv2 && mv2 != error_mark_node
 382                     && TREE_CODE (mv2) != ARRAY_TYPE)
 383                   mv2 = TYPE_MAIN_VARIANT (mv2);
 384                 for (memb = TYPE_FIELDS (TREE_VALUE (p1));
 385                      memb; memb = TREE_CHAIN (memb))
 386                   {
 387                     tree mv3 = TREE_TYPE (memb);
 388                     if (mv3 && mv3 != error_mark_node
 389                         && TREE_CODE (mv3) != ARRAY_TYPE)
 390                       mv3 = TYPE_MAIN_VARIANT (mv3);
 391                     if (comptypes (mv3, mv2))
 392                       {
 393                         TREE_VALUE (n) = composite_type (TREE_TYPE (memb),
 394                                                          TREE_VALUE (p2));
 395                         if (pedantic)
 396                           pedwarn ("function types not truly compatible in ISO C");
 397                         goto parm_done;
 398                       }
 399                   }
 400               }
 401             if (TREE_CODE (TREE_VALUE (p2)) == UNION_TYPE
 402                 && TREE_VALUE (p2) != TREE_VALUE (p1))
 403               {
 404                 tree memb;
 405                 tree mv1 = TREE_VALUE (p1);
 406                 if (mv1 && mv1 != error_mark_node
 407                     && TREE_CODE (mv1) != ARRAY_TYPE)
 408                   mv1 = TYPE_MAIN_VARIANT (mv1);
 409                 for (memb = TYPE_FIELDS (TREE_VALUE (p2));
 410                      memb; memb = TREE_CHAIN (memb))
 411                   {
 412                     tree mv3 = TREE_TYPE (memb);
 413                     if (mv3 && mv3 != error_mark_node
 414                         && TREE_CODE (mv3) != ARRAY_TYPE)
 415                       mv3 = TYPE_MAIN_VARIANT (mv3);
 416                     if (comptypes (mv3, mv1))
 417                       {
 418                         TREE_VALUE (n) = composite_type (TREE_TYPE (memb),
 419                                                          TREE_VALUE (p1));
 420                         if (pedantic)
 421                           pedwarn ("function types not truly compatible in ISO C");
 422                         goto parm_done;
 423                       }
 424                   }
 425               }
 426             TREE_VALUE (n) = composite_type (TREE_VALUE (p1), TREE_VALUE (p2));
 427           parm_done: ;
 428           }
 429
 430         c_override_global_bindings_to_false = false;
 431         t1 = build_function_type (valtype, newargs);
 432         t1 = qualify_type (t1, t2);
 433         /* ... falls through ...  */
 434       }
 435
 436     default:
 437       return build_type_attribute_variant (t1, attributes);
 438     }
 439
 440 }
 441
 442 /* Return the type of a conditional expression between pointers to
 443    possibly differently qualified versions of compatible types.
 444
 445    We assume that comp_target_types has already been done and returned
 446    nonzero; if that isn't so, this may crash.  */
 447
 448 static tree
 449 common_pointer_type (tree t1, tree t2)
 450 {
 451   tree attributes;
 452   tree pointed_to_1, mv1;
 453   tree pointed_to_2, mv2;
 454   tree target;
 455
 456   /* Save time if the two types are the same.  */
 457
 458   if (t1 == t2) return t1;
 459
 460   /* If one type is nonsense, use the other.  */
 461   if (t1 == error_mark_node)
 462     return t2;
 463   if (t2 == error_mark_node)
 464     return t1;
 465
 466   gcc_assert (TREE_CODE (t1) == POINTER_TYPE
 467               && TREE_CODE (t2) == POINTER_TYPE);
 468
 469   /* Merge the attributes.  */
 470   attributes = targetm.merge_type_attributes (t1, t2);
 471
 472   /* Find the composite type of the target types, and combine the
 473      qualifiers of the two types' targets.  Do not lose qualifiers on
 474      array element types by taking the TYPE_MAIN_VARIANT.  */
 475   mv1 = pointed_to_1 = TREE_TYPE (t1);
 476   mv2 = pointed_to_2 = TREE_TYPE (t2);
 477   if (TREE_CODE (mv1) != ARRAY_TYPE)
 478     mv1 = TYPE_MAIN_VARIANT (pointed_to_1);
 479   if (TREE_CODE (mv2) != ARRAY_TYPE)
 480     mv2 = TYPE_MAIN_VARIANT (pointed_to_2);
 481   target = composite_type (mv1, mv2);
 482   t1 = build_pointer_type (c_build_qualified_type
 483                            (target,
 484                             TYPE_QUALS (pointed_to_1) |
 485                             TYPE_QUALS (pointed_to_2)));
 486   return build_type_attribute_variant (t1, attributes);
 487 }
 488
 489 /* Return the common type for two arithmetic types under the usual
 490    arithmetic conversions.  The default conversions have already been
 491    applied, and enumerated types converted to their compatible integer
 492    types.  The resulting type is unqualified and has no attributes.
 493
 494    This is the type for the result of most arithmetic operations
 495    if the operands have the given two types.  */
 496
 497 static tree
 498 c_common_type (tree t1, tree t2)
 499 {
 500   enum tree_code code1;
 501   enum tree_code code2;
 502
 503   /* If one type is nonsense, use the other.  */
 504   if (t1 == error_mark_node)
 505     return t2;
 506   if (t2 == error_mark_node)
 507     return t1;
 508
 509   if (TYPE_QUALS (t1) != TYPE_UNQUALIFIED)
 510     t1 = TYPE_MAIN_VARIANT (t1);
 511
 512   if (TYPE_QUALS (t2) != TYPE_UNQUALIFIED)
 513     t2 = TYPE_MAIN_VARIANT (t2);
 514
 515   if (TYPE_ATTRIBUTES (t1) != NULL_TREE)
 516     t1 = build_type_attribute_variant (t1, NULL_TREE);
 517
 518   if (TYPE_ATTRIBUTES (t2) != NULL_TREE)
 519     t2 = build_type_attribute_variant (t2, NULL_TREE);
 520
 521   /* Save time if the two types are the same.  */
 522
 523   if (t1 == t2) return t1;
 524
 525   code1 = TREE_CODE (t1);
 526   code2 = TREE_CODE (t2);
 527
 528   gcc_assert (code1 == VECTOR_TYPE || code1 == COMPLEX_TYPE
 529               || code1 == REAL_TYPE || code1 == INTEGER_TYPE);
 530   gcc_assert (code2 == VECTOR_TYPE || code2 == COMPLEX_TYPE
 531               || code2 == REAL_TYPE || code2 == INTEGER_TYPE);
 532
 533   /* If one type is a vector type, return that type.  (How the usual
 534      arithmetic conversions apply to the vector types extension is not
 535      precisely specified.)  */
 536   if (code1 == VECTOR_TYPE)
 537     return t1;
 538
 539   if (code2 == VECTOR_TYPE)
 540     return t2;
 541
 542   /* If one type is complex, form the common type of the non-complex
 543      components, then make that complex.  Use T1 or T2 if it is the
 544      required type.  */
 545   if (code1 == COMPLEX_TYPE || code2 == COMPLEX_TYPE)
 546     {
 547       tree subtype1 = code1 == COMPLEX_TYPE ? TREE_TYPE (t1) : t1;
 548       tree subtype2 = code2 == COMPLEX_TYPE ? TREE_TYPE (t2) : t2;
 549       tree subtype = c_common_type (subtype1, subtype2);
 550
 551       if (code1 == COMPLEX_TYPE && TREE_TYPE (t1) == subtype)
 552         return t1;
 553       else if (code2 == COMPLEX_TYPE && TREE_TYPE (t2) == subtype)
 554         return t2;
 555       else
 556         return build_complex_type (subtype);
 557     }
 558
 559   /* If only one is real, use it as the result.  */
 560
 561   if (code1 == REAL_TYPE && code2 != REAL_TYPE)
 562     return t1;
 563
 564   if (code2 == REAL_TYPE && code1 != REAL_TYPE)
 565     return t2;
 566
 567   /* Both real or both integers; use the one with greater precision.  */
 568
 569   if (TYPE_PRECISION (t1) > TYPE_PRECISION (t2))
 570     return t1;
 571   else if (TYPE_PRECISION (t2) > TYPE_PRECISION (t1))
 572     return t2;
 573
 574   /* Same precision.  Prefer long longs to longs to ints when the
 575      same precision, following the C99 rules on integer type rank
 576      (which are equivalent to the C90 rules for C90 types).  */
 577
 578   if (TYPE_MAIN_VARIANT (t1) == long_long_unsigned_type_node
 579       || TYPE_MAIN_VARIANT (t2) == long_long_unsigned_type_node)
 580     return long_long_unsigned_type_node;
 581
 582   if (TYPE_MAIN_VARIANT (t1) == long_long_integer_type_node
 583       || TYPE_MAIN_VARIANT (t2) == long_long_integer_type_node)
 584     {
 585       if (TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 586         return long_long_unsigned_type_node;
 587       else
 588         return long_long_integer_type_node;
 589     }
 590
 591   if (TYPE_MAIN_VARIANT (t1) == long_unsigned_type_node
 592       || TYPE_MAIN_VARIANT (t2) == long_unsigned_type_node)
 593     return long_unsigned_type_node;
 594
 595   if (TYPE_MAIN_VARIANT (t1) == long_integer_type_node
 596       || TYPE_MAIN_VARIANT (t2) == long_integer_type_node)
 597     {
 598       /* But preserve unsignedness from the other type,
 599          since long cannot hold all the values of an unsigned int.  */
 600       if (TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 601         return long_unsigned_type_node;
 602       else
 603         return long_integer_type_node;
 604     }
 605
 606   /* Likewise, prefer long double to double even if same size.  */
 607   if (TYPE_MAIN_VARIANT (t1) == long_double_type_node
 608       || TYPE_MAIN_VARIANT (t2) == long_double_type_node)
 609     return long_double_type_node;
 610
 611   /* Otherwise prefer the unsigned one.  */
 612
 613   if (TYPE_UNSIGNED (t1))
 614     return t1;
 615   else
 616     return t2;
 617 }
 618 \f
 619 /* Wrapper around c_common_type that is used by c-common.c.  ENUMERAL_TYPEs
 620    are allowed here and are converted to their compatible integer types.
 621    BOOLEAN_TYPEs are allowed here and return either boolean_type_node or
 622    preferably a non-Boolean type as the common type.  */
 623 tree
 624 common_type (tree t1, tree t2)
 625 {
 626   if (TREE_CODE (t1) == ENUMERAL_TYPE)
 627     t1 = c_common_type_for_size (TYPE_PRECISION (t1), 1);
 628   if (TREE_CODE (t2) == ENUMERAL_TYPE)
 629     t2 = c_common_type_for_size (TYPE_PRECISION (t2), 1);
 630
 631   /* If both types are BOOLEAN_TYPE, then return boolean_type_node.  */
 632   if (TREE_CODE (t1) == BOOLEAN_TYPE
 633       && TREE_CODE (t2) == BOOLEAN_TYPE)
 634     return boolean_type_node;
 635
 636   /* If either type is BOOLEAN_TYPE, then return the other.  */
 637   if (TREE_CODE (t1) == BOOLEAN_TYPE)
 638     return t2;
 639   if (TREE_CODE (t2) == BOOLEAN_TYPE)
 640     return t1;
 641
 642   return c_common_type (t1, t2);
 643 }
 644 \f
 645 /* Return 1 if TYPE1 and TYPE2 are compatible types for assignment
 646    or various other operations.  Return 2 if they are compatible
 647    but a warning may be needed if you use them together.  */
 648
 649 int
 650 comptypes (tree type1, tree type2)
 651 {
 652   tree t1 = type1;
 653   tree t2 = type2;
 654   int attrval, val;
 655
 656   /* Suppress errors caused by previously reported errors.  */
 657
 658   if (t1 == t2 || !t1 || !t2
 659       || TREE_CODE (t1) == ERROR_MARK || TREE_CODE (t2) == ERROR_MARK)
 660     return 1;
 661
 662   /* If either type is the internal version of sizetype, return the
 663      language version.  */
 664   if (TREE_CODE (t1) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t1)
 665       && TYPE_ORIG_SIZE_TYPE (t1))
 666     t1 = TYPE_ORIG_SIZE_TYPE (t1);
 667
 668   if (TREE_CODE (t2) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t2)
 669       && TYPE_ORIG_SIZE_TYPE (t2))
 670     t2 = TYPE_ORIG_SIZE_TYPE (t2);
 671
 672
 673   /* Enumerated types are compatible with integer types, but this is
 674      not transitive: two enumerated types in the same translation unit
 675      are compatible with each other only if they are the same type.  */
 676
 677   if (TREE_CODE (t1) == ENUMERAL_TYPE && TREE_CODE (t2) != ENUMERAL_TYPE)
 678     t1 = c_common_type_for_size (TYPE_PRECISION (t1), TYPE_UNSIGNED (t1));
 679   else if (TREE_CODE (t2) == ENUMERAL_TYPE && TREE_CODE (t1) != ENUMERAL_TYPE)
 680     t2 = c_common_type_for_size (TYPE_PRECISION (t2), TYPE_UNSIGNED (t2));
 681
 682   if (t1 == t2)
 683     return 1;
 684
 685   /* Different classes of types can't be compatible.  */
 686
 687   if (TREE_CODE (t1) != TREE_CODE (t2))
 688     return 0;
 689
 690   /* Qualifiers must match. C99 6.7.3p9 */
 691
 692   if (TYPE_QUALS (t1) != TYPE_QUALS (t2))
 693     return 0;
 694
 695   /* Allow for two different type nodes which have essentially the same
 696      definition.  Note that we already checked for equality of the type
 697      qualifiers (just above).  */
 698
 699   if (TREE_CODE (t1) != ARRAY_TYPE
 700       && TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
 701     return 1;
 702
 703   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
 704   if (!(attrval = targetm.comp_type_attributes (t1, t2)))
 705      return 0;
 706
 707   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
 708   val = 0;
 709
 710   switch (TREE_CODE (t1))
 711     {
 712     case POINTER_TYPE:
 713       /* Do not remove mode or aliasing information.  */
 714       if (TYPE_MODE (t1) != TYPE_MODE (t2)
 715           || TYPE_REF_CAN_ALIAS_ALL (t1) != TYPE_REF_CAN_ALIAS_ALL (t2))
 716         break;
 717       val = (TREE_TYPE (t1) == TREE_TYPE (t2)
 718              ? 1 : comptypes (TREE_TYPE (t1), TREE_TYPE (t2)));
 719       break;
 720
 721     case FUNCTION_TYPE:
 722       val = function_types_compatible_p (t1, t2);
 723       break;
 724
 725     case ARRAY_TYPE:
 726       {
 727         tree d1 = TYPE_DOMAIN (t1);
 728         tree d2 = TYPE_DOMAIN (t2);
 729         bool d1_variable, d2_variable;
 730         bool d1_zero, d2_zero;
 731         val = 1;
 732
 733         /* Target types must match incl. qualifiers.  */
 734         if (TREE_TYPE (t1) != TREE_TYPE (t2)
 735             && 0 == (val = comptypes (TREE_TYPE (t1), TREE_TYPE (t2))))
 736           return 0;
 737
 738         /* Sizes must match unless one is missing or variable.  */
 739         if (d1 == 0 || d2 == 0 || d1 == d2)
 740           break;
 741
 742         d1_zero = !TYPE_MAX_VALUE (d1);
 743         d2_zero = !TYPE_MAX_VALUE (d2);
 744
 745         d1_variable = (!d1_zero
 746                        && (TREE_CODE (TYPE_MIN_VALUE (d1)) != INTEGER_CST
 747                            || TREE_CODE (TYPE_MAX_VALUE (d1)) != INTEGER_CST));
 748         d2_variable = (!d2_zero
 749                        && (TREE_CODE (TYPE_MIN_VALUE (d2)) != INTEGER_CST
 750                            || TREE_CODE (TYPE_MAX_VALUE (d2)) != INTEGER_CST));
 751
 752         if (d1_variable || d2_variable)
 753           break;
 754         if (d1_zero && d2_zero)
 755           break;
 756         if (d1_zero || d2_zero
 757             || !tree_int_cst_equal (TYPE_MIN_VALUE (d1), TYPE_MIN_VALUE (d2))
 758             || !tree_int_cst_equal (TYPE_MAX_VALUE (d1), TYPE_MAX_VALUE (d2)))
 759           val = 0;
 760
 761         break;
 762       }
 763
 764     case ENUMERAL_TYPE:
 765     case RECORD_TYPE:
 766     case UNION_TYPE:
 767       if (val != 1 && !same_translation_unit_p (t1, t2))
 768         val = tagged_types_tu_compatible_p (t1, t2);
 769       break;
 770
 771     case VECTOR_TYPE:
 772       val = TYPE_VECTOR_SUBPARTS (t1) == TYPE_VECTOR_SUBPARTS (t2)
 773             && comptypes (TREE_TYPE (t1), TREE_TYPE (t2));
 774       break;
 775
 776     default:
 777       break;
 778     }
 779   return attrval == 2 && val == 1 ? 2 : val;
 780 }
 781
 782 /* Return 1 if TTL and TTR are pointers to types that are equivalent,
 783    ignoring their qualifiers.  */
 784
 785 static int
 786 comp_target_types (tree ttl, tree ttr)
 787 {
 788   int val;
 789   tree mvl, mvr;
 790
 791   /* Do not lose qualifiers on element types of array types that are
 792      pointer targets by taking their TYPE_MAIN_VARIANT.  */
 793   mvl = TREE_TYPE (ttl);
 794   mvr = TREE_TYPE (ttr);
 795   if (TREE_CODE (mvl) != ARRAY_TYPE)
 796     mvl = TYPE_MAIN_VARIANT (mvl);
 797   if (TREE_CODE (mvr) != ARRAY_TYPE)
 798     mvr = TYPE_MAIN_VARIANT (mvr);
 799   val = comptypes (mvl, mvr);
 800
 801   if (val == 2 && pedantic)
 802     pedwarn ("types are not quite compatible");
 803   return val;
 804 }
 805 \f
 806 /* Subroutines of `comptypes'.  */
 807
 808 /* Determine whether two trees derive from the same translation unit.
 809    If the CONTEXT chain ends in a null, that tree's context is still
 810    being parsed, so if two trees have context chains ending in null,
 811    they're in the same translation unit.  */
 812 int
 813 same_translation_unit_p (tree t1, tree t2)
 814 {
 815   while (t1 && TREE_CODE (t1) != TRANSLATION_UNIT_DECL)
 816     switch (TREE_CODE_CLASS (TREE_CODE (t1)))
 817       {
 818       case tcc_declaration:
 819         t1 = DECL_CONTEXT (t1); break;
 820       case tcc_type:
 821         t1 = TYPE_CONTEXT (t1); break;
 822       case tcc_exceptional:
 823         t1 = BLOCK_SUPERCONTEXT (t1); break;  /* assume block */
 824       default: gcc_unreachable ();
 825       }
 826
 827   while (t2 && TREE_CODE (t2) != TRANSLATION_UNIT_DECL)
 828     switch (TREE_CODE_CLASS (TREE_CODE (t2)))
 829       {
 830       case tcc_declaration:
 831         t2 = DECL_CONTEXT (t2); break;
 832       case tcc_type:
 833         t2 = TYPE_CONTEXT (t2); break;
 834       case tcc_exceptional:
 835         t2 = BLOCK_SUPERCONTEXT (t2); break;  /* assume block */
 836       default: gcc_unreachable ();
 837       }
 838
 839   return t1 == t2;
 840 }
 841
 842 /* The C standard says that two structures in different translation
 843    units are compatible with each other only if the types of their
 844    fields are compatible (among other things).  So, consider two copies
 845    of this structure:  */
 846
 847 struct tagged_tu_seen {
 848   const struct tagged_tu_seen * next;
 849   tree t1;
 850   tree t2;
 851 };
 852
 853 /* Can they be compatible with each other?  We choose to break the
 854    recursion by allowing those types to be compatible.  */
 855
 856 static const struct tagged_tu_seen * tagged_tu_seen_base;
 857
 858 /* Return 1 if two 'struct', 'union', or 'enum' types T1 and T2 are
 859    compatible.  If the two types are not the same (which has been
 860    checked earlier), this can only happen when multiple translation
 861    units are being compiled.  See C99 6.2.7 paragraph 1 for the exact
 862    rules.  */
 863
 864 static int
 865 tagged_types_tu_compatible_p (tree t1, tree t2)
 866 {
 867   tree s1, s2;
 868   bool needs_warning = false;
 869
 870   /* We have to verify that the tags of the types are the same.  This
 871      is harder than it looks because this may be a typedef, so we have
 872      to go look at the original type.  It may even be a typedef of a
 873      typedef...
 874      In the case of compiler-created builtin structs the TYPE_DECL
 875      may be a dummy, with no DECL_ORIGINAL_TYPE.  Don't fault.  */
 876   while (TYPE_NAME (t1)
 877          && TREE_CODE (TYPE_NAME (t1)) == TYPE_DECL
 878          && DECL_ORIGINAL_TYPE (TYPE_NAME (t1)))
 879     t1 = DECL_ORIGINAL_TYPE (TYPE_NAME (t1));
 880
 881   while (TYPE_NAME (t2)
 882          && TREE_CODE (TYPE_NAME (t2)) == TYPE_DECL
 883          && DECL_ORIGINAL_TYPE (TYPE_NAME (t2)))
 884     t2 = DECL_ORIGINAL_TYPE (TYPE_NAME (t2));
 885
 886   /* C90 didn't have the requirement that the two tags be the same.  */
 887   if (flag_isoc99 && TYPE_NAME (t1) != TYPE_NAME (t2))
 888     return 0;
 889
 890   /* C90 didn't say what happened if one or both of the types were
 891      incomplete; we choose to follow C99 rules here, which is that they
 892      are compatible.  */
 893   if (TYPE_SIZE (t1) == NULL
 894       || TYPE_SIZE (t2) == NULL)
 895     return 1;
 896
 897   {
 898     const struct tagged_tu_seen * tts_i;
 899     for (tts_i = tagged_tu_seen_base; tts_i != NULL; tts_i = tts_i->next)
 900       if (tts_i->t1 == t1 && tts_i->t2 == t2)
 901         return 1;
 902   }
 903
 904   switch (TREE_CODE (t1))
 905     {
 906     case ENUMERAL_TYPE:
 907       {
 908
 909         /* Speed up the case where the type values are in the same order.  */
 910         tree tv1 = TYPE_VALUES (t1);
 911         tree tv2 = TYPE_VALUES (t2);
 912
 913         if (tv1 == tv2)
 914           return 1;
 915
 916         for (;tv1 && tv2; tv1 = TREE_CHAIN (tv1), tv2 = TREE_CHAIN (tv2))
 917           {
 918             if (TREE_PURPOSE (tv1) != TREE_PURPOSE (tv2))
 919               break;
 920             if (simple_cst_equal (TREE_VALUE (tv1), TREE_VALUE (tv2)) != 1)
 921               return 0;
 922           }
 923
 924         if (tv1 == NULL_TREE && tv2 == NULL_TREE)
 925           return 1;
 926         if (tv1 == NULL_TREE || tv2 == NULL_TREE)
 927           return 0;
 928
 929         if (list_length (TYPE_VALUES (t1)) != list_length (TYPE_VALUES (t2)))
 930           return 0;
 931
 932         for (s1 = TYPE_VALUES (t1); s1; s1 = TREE_CHAIN (s1))
 933           {
 934             s2 = purpose_member (TREE_PURPOSE (s1), TYPE_VALUES (t2));
 935             if (s2 == NULL
 936                 || simple_cst_equal (TREE_VALUE (s1), TREE_VALUE (s2)) != 1)
 937               return 0;
 938           }
 939         return 1;
 940       }
 941
 942     case UNION_TYPE:
 943       {
 944         if (list_length (TYPE_FIELDS (t1)) != list_length (TYPE_FIELDS (t2)))
 945           return 0;
 946
 947         for (s1 = TYPE_FIELDS (t1); s1; s1 = TREE_CHAIN (s1))
 948           {
 949             bool ok = false;
 950             struct tagged_tu_seen tts;
 951
 952             tts.next = tagged_tu_seen_base;
 953             tts.t1 = t1;
 954             tts.t2 = t2;
 955             tagged_tu_seen_base = &tts;
 956
 957             if (DECL_NAME (s1) != NULL)
 958               for (s2 = TYPE_FIELDS (t2); s2; s2 = TREE_CHAIN (s2))
 959                 if (DECL_NAME (s1) == DECL_NAME (s2))
 960                   {
 961                     int result;
 962                     result = comptypes (TREE_TYPE (s1), TREE_TYPE (s2));
 963                     if (result == 0)
 964                       break;
 965                     if (result == 2)
 966                       needs_warning = true;
 967
 968                     if (TREE_CODE (s1) == FIELD_DECL
 969                         && simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
 970                                              DECL_FIELD_BIT_OFFSET (s2)) != 1)
 971                       break;
 972
 973                     ok = true;
 974                     break;
 975                   }
 976             tagged_tu_seen_base = tts.next;
 977             if (!ok)
 978               return 0;
 979           }
 980         return needs_warning ? 2 : 1;
 981       }
 982
 983     case RECORD_TYPE:
 984       {
 985         struct tagged_tu_seen tts;
 986
 987         tts.next = tagged_tu_seen_base;
 988         tts.t1 = t1;
 989         tts.t2 = t2;
 990         tagged_tu_seen_base = &tts;
 991
 992         for (s1 = TYPE_FIELDS (t1), s2 = TYPE_FIELDS (t2);
 993              s1 && s2;
 994              s1 = TREE_CHAIN (s1), s2 = TREE_CHAIN (s2))
 995           {
 996             int result;
 997             if (TREE_CODE (s1) != TREE_CODE (s2)
 998                 || DECL_NAME (s1) != DECL_NAME (s2))
 999               break;
1000             result = comptypes (TREE_TYPE (s1), TREE_TYPE (s2));
1001             if (result == 0)
1002               break;
1003             if (result == 2)
1004               needs_warning = true;
1005
1006             if (TREE_CODE (s1) == FIELD_DECL
1007                 && simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
1008                                      DECL_FIELD_BIT_OFFSET (s2)) != 1)
1009               break;
1010           }
1011         tagged_tu_seen_base = tts.next;
1012         if (s1 && s2)
1013           return 0;
1014         return needs_warning ? 2 : 1;
1015       }
1016
1017     default:
1018       gcc_unreachable ();
1019     }
1020 }
1021
1022 /* Return 1 if two function types F1 and F2 are compatible.
1023    If either type specifies no argument types,
1024    the other must specify a fixed number of self-promoting arg types.
1025    Otherwise, if one type specifies only the number of arguments,
1026    the other must specify that number of self-promoting arg types.
1027    Otherwise, the argument types must match.  */
1028
1029 static int
1030 function_types_compatible_p (tree f1, tree f2)
1031 {
1032   tree args1, args2;
1033   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
1034   int val = 1;
1035   int val1;
1036   tree ret1, ret2;
1037
1038   ret1 = TREE_TYPE (f1);
1039   ret2 = TREE_TYPE (f2);
1040
1041   /* 'volatile' qualifiers on a function's return type used to mean
1042      the function is noreturn.  */
1043   if (TYPE_VOLATILE (ret1) != TYPE_VOLATILE (ret2))
1044     pedwarn ("function return types not compatible due to %<volatile%>");
1045   if (TYPE_VOLATILE (ret1))
1046     ret1 = build_qualified_type (TYPE_MAIN_VARIANT (ret1),
1047                                  TYPE_QUALS (ret1) & ~TYPE_QUAL_VOLATILE);
1048   if (TYPE_VOLATILE (ret2))
1049     ret2 = build_qualified_type (TYPE_MAIN_VARIANT (ret2),
1050                                  TYPE_QUALS (ret2) & ~TYPE_QUAL_VOLATILE);
1051   val = comptypes (ret1, ret2);
1052   if (val == 0)
1053     return 0;
1054
1055   args1 = TYPE_ARG_TYPES (f1);
1056   args2 = TYPE_ARG_TYPES (f2);
1057
1058   /* An unspecified parmlist matches any specified parmlist
1059      whose argument types don't need default promotions.  */
1060
1061   if (args1 == 0)
1062     {
1063       if (!self_promoting_args_p (args2))
1064         return 0;
1065       /* If one of these types comes from a non-prototype fn definition,
1066          compare that with the other type's arglist.
1067          If they don't match, ask for a warning (but no error).  */
1068       if (TYPE_ACTUAL_ARG_TYPES (f1)
1069           && 1 != type_lists_compatible_p (args2, TYPE_ACTUAL_ARG_TYPES (f1)))
1070         val = 2;
1071       return val;
1072     }
1073   if (args2 == 0)
1074     {
1075       if (!self_promoting_args_p (args1))
1076         return 0;
1077       if (TYPE_ACTUAL_ARG_TYPES (f2)
1078           && 1 != type_lists_compatible_p (args1, TYPE_ACTUAL_ARG_TYPES (f2)))
1079         val = 2;
1080       return val;
1081     }
1082
1083   /* Both types have argument lists: compare them and propagate results.  */
1084   val1 = type_lists_compatible_p (args1, args2);
1085   return val1 != 1 ? val1 : val;
1086 }
1087
1088 /* Check two lists of types for compatibility,
1089    returning 0 for incompatible, 1 for compatible,
1090    or 2 for compatible with warning.  */
1091
1092 static int
1093 type_lists_compatible_p (tree args1, tree args2)
1094 {
1095   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
1096   int val = 1;
1097   int newval = 0;
1098
1099   while (1)
1100     {
1101       tree a1, mv1, a2, mv2;
1102       if (args1 == 0 && args2 == 0)
1103         return val;
1104       /* If one list is shorter than the other,
1105          they fail to match.  */
1106       if (args1 == 0 || args2 == 0)
1107         return 0;
1108       mv1 = a1 = TREE_VALUE (args1);
1109       mv2 = a2 = TREE_VALUE (args2);
1110       if (mv1 && mv1 != error_mark_node && TREE_CODE (mv1) != ARRAY_TYPE)
1111         mv1 = TYPE_MAIN_VARIANT (mv1);
1112       if (mv2 && mv2 != error_mark_node && TREE_CODE (mv2) != ARRAY_TYPE)
1113         mv2 = TYPE_MAIN_VARIANT (mv2);
1114       /* A null pointer instead of a type
1115          means there is supposed to be an argument
1116          but nothing is specified about what type it has.
1117          So match anything that self-promotes.  */
1118       if (a1 == 0)
1119         {
1120           if (c_type_promotes_to (a2) != a2)
1121             return 0;
1122         }
1123       else if (a2 == 0)
1124         {
1125           if (c_type_promotes_to (a1) != a1)
1126             return 0;
1127         }
1128       /* If one of the lists has an error marker, ignore this arg.  */
1129       else if (TREE_CODE (a1) == ERROR_MARK
1130                || TREE_CODE (a2) == ERROR_MARK)
1131         ;
1132       else if (!(newval = comptypes (mv1, mv2)))
1133         {
1134           /* Allow  wait (union {union wait *u; int *i} *)
1135              and  wait (union wait *)  to be compatible.  */
1136           if (TREE_CODE (a1) == UNION_TYPE
1137               && (TYPE_NAME (a1) == 0
1138                   || TYPE_TRANSPARENT_UNION (a1))
1139               && TREE_CODE (TYPE_SIZE (a1)) == INTEGER_CST
1140               && tree_int_cst_equal (TYPE_SIZE (a1),
1141                                      TYPE_SIZE (a2)))
1142             {
1143               tree memb;
1144               for (memb = TYPE_FIELDS (a1);
1145                    memb; memb = TREE_CHAIN (memb))
1146                 {
1147                   tree mv3 = TREE_TYPE (memb);
1148                   if (mv3 && mv3 != error_mark_node
1149                       && TREE_CODE (mv3) != ARRAY_TYPE)
1150                     mv3 = TYPE_MAIN_VARIANT (mv3);
1151                   if (comptypes (mv3, mv2))
1152                     break;
1153                 }
1154               if (memb == 0)
1155                 return 0;
1156             }
1157           else if (TREE_CODE (a2) == UNION_TYPE
1158                    && (TYPE_NAME (a2) == 0
1159                        || TYPE_TRANSPARENT_UNION (a2))
1160                    && TREE_CODE (TYPE_SIZE (a2)) == INTEGER_CST
1161                    && tree_int_cst_equal (TYPE_SIZE (a2),
1162                                           TYPE_SIZE (a1)))
1163             {
1164               tree memb;
1165               for (memb = TYPE_FIELDS (a2);
1166                    memb; memb = TREE_CHAIN (memb))
1167                 {
1168                   tree mv3 = TREE_TYPE (memb);
1169                   if (mv3 && mv3 != error_mark_node
1170                       && TREE_CODE (mv3) != ARRAY_TYPE)
1171                     mv3 = TYPE_MAIN_VARIANT (mv3);
1172                   if (comptypes (mv3, mv1))
1173                     break;
1174                 }
1175               if (memb == 0)
1176                 return 0;
1177             }
1178           else
1179             return 0;
1180         }
1181
1182       /* comptypes said ok, but record if it said to warn.  */
1183       if (newval > val)
1184         val = newval;
1185
1186       args1 = TREE_CHAIN (args1);
1187       args2 = TREE_CHAIN (args2);
1188     }
1189 }
1190 \f
1191 /* Compute the size to increment a pointer by.  */
1192
1193 static tree
1194 c_size_in_bytes (tree type)
1195 {
1196   enum tree_code code = TREE_CODE (type);
1197
1198   if (code == FUNCTION_TYPE || code == VOID_TYPE || code == ERROR_MARK)
1199     return size_one_node;
1200
1201   if (!COMPLETE_OR_VOID_TYPE_P (type))
1202     {
1203       error ("arithmetic on pointer to an incomplete type");
1204       return size_one_node;
1205     }
1206
1207   /* Convert in case a char is more than one unit.  */
1208   return size_binop (CEIL_DIV_EXPR, TYPE_SIZE_UNIT (type),
1209                      size_int (TYPE_PRECISION (char_type_node)
1210                                / BITS_PER_UNIT));
1211 }
1212 \f
1213 /* Return either DECL or its known constant value (if it has one).  */
1214
1215 tree
1216 decl_constant_value (tree decl)
1217 {
1218   if (/* Don't change a variable array bound or initial value to a constant
1219          in a place where a variable is invalid.  Note that DECL_INITIAL
1220          isn't valid for a PARM_DECL.  */
1221       current_function_decl != 0
1222       && TREE_CODE (decl) != PARM_DECL
1223       && !TREE_THIS_VOLATILE (decl)
1224       && TREE_READONLY (decl)
1225       && DECL_INITIAL (decl) != 0
1226       && TREE_CODE (DECL_INITIAL (decl)) != ERROR_MARK
1227       /* This is invalid if initial value is not constant.
1228          If it has either a function call, a memory reference,
1229          or a variable, then re-evaluating it could give different results.  */
1230       && TREE_CONSTANT (DECL_INITIAL (decl))
1231       /* Check for cases where this is sub-optimal, even though valid.  */
1232       && TREE_CODE (DECL_INITIAL (decl)) != CONSTRUCTOR)
1233     return DECL_INITIAL (decl);
1234   return decl;
1235 }
1236
1237 /* Return either DECL or its known constant value (if it has one), but
1238    return DECL if pedantic or DECL has mode BLKmode.  This is for
1239    bug-compatibility with the old behavior of decl_constant_value
1240    (before GCC 3.0); every use of this function is a bug and it should
1241    be removed before GCC 3.1.  It is not appropriate to use pedantic
1242    in a way that affects optimization, and BLKmode is probably not the
1243    right test for avoiding misoptimizations either.  */
1244
1245 static tree
1246 decl_constant_value_for_broken_optimization (tree decl)
1247 {
1248   tree ret;
1249
1250   if (pedantic || DECL_MODE (decl) == BLKmode)
1251     return decl;
1252
1253   ret = decl_constant_value (decl);
1254   /* Avoid unwanted tree sharing between the initializer and current
1255      function's body where the tree can be modified e.g. by the
1256      gimplifier.  */
1257   if (ret != decl && TREE_STATIC (decl))
1258     ret = unshare_expr (ret);
1259   return ret;
1260 }
1261
1262 /* Convert the array expression EXP to a pointer.  */
1263 static tree
1264 array_to_pointer_conversion (tree exp)
1265 {
1266   tree orig_exp = exp;
1267   tree type = TREE_TYPE (exp);
1268   tree adr;
1269   tree restype = TREE_TYPE (type);
1270   tree ptrtype;
1271
1272   gcc_assert (TREE_CODE (type) == ARRAY_TYPE);
1273
1274   STRIP_TYPE_NOPS (exp);
1275
1276   if (TREE_NO_WARNING (orig_exp))
1277     TREE_NO_WARNING (exp) = 1;
1278
1279   ptrtype = build_pointer_type (restype);
1280
1281   if (TREE_CODE (exp) == INDIRECT_REF)
1282     return convert (ptrtype, TREE_OPERAND (exp, 0));
1283
1284   if (TREE_CODE (exp) == VAR_DECL)
1285     {
1286       /* We are making an ADDR_EXPR of ptrtype.  This is a valid
1287          ADDR_EXPR because it's the best way of representing what
1288          happens in C when we take the address of an array and place
1289          it in a pointer to the element type.  */
1290       adr = build1 (ADDR_EXPR, ptrtype, exp);
1291       if (!c_mark_addressable (exp))
1292         return error_mark_node;
1293       TREE_SIDE_EFFECTS (adr) = 0;   /* Default would be, same as EXP.  */
1294       return adr;
1295     }
1296
1297   /* This way is better for a COMPONENT_REF since it can
1298      simplify the offset for a component.  */
1299   adr = build_unary_op (ADDR_EXPR, exp, 1);
1300   return convert (ptrtype, adr);
1301 }
1302
1303 /* Convert the function expression EXP to a pointer.  */
1304 static tree
1305 function_to_pointer_conversion (tree exp)
1306 {
1307   tree orig_exp = exp;
1308
1309   gcc_assert (TREE_CODE (TREE_TYPE (exp)) == FUNCTION_TYPE);
1310
1311   STRIP_TYPE_NOPS (exp);
1312
1313   if (TREE_NO_WARNING (orig_exp))
1314     TREE_NO_WARNING (exp) = 1;
1315
1316   return build_unary_op (ADDR_EXPR, exp, 0);
1317 }
1318
1319 /* Perform the default conversion of arrays and functions to pointers.
1320    Return the result of converting EXP.  For any other expression, just
1321    return EXP after removing NOPs.  */
1322
1323 struct c_expr
1324 default_function_array_conversion (struct c_expr exp)
1325 {
1326   tree orig_exp = exp.value;
1327   tree type = TREE_TYPE (exp.value);
1328   enum tree_code code = TREE_CODE (type);
1329
1330   switch (code)
1331     {
1332     case ARRAY_TYPE:
1333       {
1334         bool not_lvalue = false;
1335         bool lvalue_array_p;
1336
1337         while ((TREE_CODE (exp.value) == NON_LVALUE_EXPR
1338                 || TREE_CODE (exp.value) == NOP_EXPR)
1339                && TREE_TYPE (TREE_OPERAND (exp.value, 0)) == type)
1340           {
1341             if (TREE_CODE (exp.value) == NON_LVALUE_EXPR)
1342               not_lvalue = true;
1343             exp.value = TREE_OPERAND (exp.value, 0);
1344           }
1345
1346         if (TREE_NO_WARNING (orig_exp))
1347           TREE_NO_WARNING (exp.value) = 1;
1348
1349         lvalue_array_p = !not_lvalue && lvalue_p (exp.value);
1350         if (!flag_isoc99 && !lvalue_array_p)
1351           {
1352             /* Before C99, non-lvalue arrays do not decay to pointers.
1353                Normally, using such an array would be invalid; but it can
1354                be used correctly inside sizeof or as a statement expression.
1355                Thus, do not give an error here; an error will result later.  */
1356             return exp;
1357           }
1358
1359         exp.value = array_to_pointer_conversion (exp.value);
1360       }
1361       break;
1362     case FUNCTION_TYPE:
1363       exp.value = function_to_pointer_conversion (exp.value);
1364       break;
1365     default:
1366       STRIP_TYPE_NOPS (exp.value);
1367       if (TREE_NO_WARNING (orig_exp))
1368         TREE_NO_WARNING (exp.value) = 1;
1369       break;
1370     }
1371
1372   return exp;
1373 }
1374
1375
1376 /* EXP is an expression of integer type.  Apply the integer promotions
1377    to it and return the promoted value.  */
1378
1379 tree
1380 perform_integral_promotions (tree exp)
1381 {
1382   tree type = TREE_TYPE (exp);
1383   enum tree_code code = TREE_CODE (type);
1384
1385   gcc_assert (INTEGRAL_TYPE_P (type));
1386
1387   /* Normally convert enums to int,
1388      but convert wide enums to something wider.  */
1389   if (code == ENUMERAL_TYPE)
1390     {
1391       type = c_common_type_for_size (MAX (TYPE_PRECISION (type),
1392                                           TYPE_PRECISION (integer_type_node)),
1393                                      ((TYPE_PRECISION (type)
1394                                        >= TYPE_PRECISION (integer_type_node))
1395                                       && TYPE_UNSIGNED (type)));
1396
1397       return convert (type, exp);
1398     }
1399
1400   /* ??? This should no longer be needed now bit-fields have their
1401      proper types.  */
1402   if (TREE_CODE (exp) == COMPONENT_REF
1403       && DECL_C_BIT_FIELD (TREE_OPERAND (exp, 1))
1404       /* If it's thinner than an int, promote it like a
1405          c_promoting_integer_type_p, otherwise leave it alone.  */
1406       && 0 > compare_tree_int (DECL_SIZE (TREE_OPERAND (exp, 1)),
1407                                TYPE_PRECISION (integer_type_node)))
1408     return convert (integer_type_node, exp);
1409
1410   if (c_promoting_integer_type_p (type))
1411     {
1412       /* Preserve unsignedness if not really getting any wider.  */
1413       if (TYPE_UNSIGNED (type)
1414           && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
1415         return convert (unsigned_type_node, exp);
1416
1417       return convert (integer_type_node, exp);
1418     }
1419
1420   return exp;
1421 }
1422
1423
1424 /* Perform default promotions for C data used in expressions.
1425    Enumeral types or short or char are converted to int.
1426    In addition, manifest constants symbols are replaced by their values.  */
1427
1428 tree
1429 default_conversion (tree exp)
1430 {
1431   tree orig_exp;
1432   tree type = TREE_TYPE (exp);
1433   enum tree_code code = TREE_CODE (type);
1434
1435   /* Functions and arrays have been converted during parsing.  */
1436   gcc_assert (code != FUNCTION_TYPE);
1437   if (code == ARRAY_TYPE)
1438     return exp;
1439
1440   /* Constants can be used directly unless they're not loadable.  */
1441   if (TREE_CODE (exp) == CONST_DECL)
1442     exp = DECL_INITIAL (exp);
1443
1444   /* Replace a nonvolatile const static variable with its value unless
1445      it is an array, in which case we must be sure that taking the
1446      address of the array produces consistent results.  */
1447   else if (optimize && TREE_CODE (exp) == VAR_DECL && code != ARRAY_TYPE)
1448     {
1449       exp = decl_constant_value_for_broken_optimization (exp);
1450       type = TREE_TYPE (exp);
1451     }
1452
1453   /* Strip no-op conversions.  */
1454   orig_exp = exp;
1455   STRIP_TYPE_NOPS (exp);
1456
1457   if (TREE_NO_WARNING (orig_exp))
1458     TREE_NO_WARNING (exp) = 1;
1459
1460   if (INTEGRAL_TYPE_P (type))
1461     return perform_integral_promotions (exp);
1462
1463   if (code == VOID_TYPE)
1464     {
1465       error ("void value not ignored as it ought to be");
1466       return error_mark_node;
1467     }
1468   return exp;
1469 }
1470 \f
1471 /* Look up COMPONENT in a structure or union DECL.
1472
1473    If the component name is not found, returns NULL_TREE.  Otherwise,
1474    the return value is a TREE_LIST, with each TREE_VALUE a FIELD_DECL
1475    stepping down the chain to the component, which is in the last
1476    TREE_VALUE of the list.  Normally the list is of length one, but if
1477    the component is embedded within (nested) anonymous structures or
1478    unions, the list steps down the chain to the component.  */
1479
1480 static tree
1481 lookup_field (tree decl, tree component)
1482 {
1483   tree type = TREE_TYPE (decl);
1484   tree field;
1485
1486   /* If TYPE_LANG_SPECIFIC is set, then it is a sorted array of pointers
1487      to the field elements.  Use a binary search on this array to quickly
1488      find the element.  Otherwise, do a linear search.  TYPE_LANG_SPECIFIC
1489      will always be set for structures which have many elements.  */
1490
1491   if (TYPE_LANG_SPECIFIC (type) && TYPE_LANG_SPECIFIC (type)->s)
1492     {
1493       int bot, top, half;
1494       tree *field_array = &TYPE_LANG_SPECIFIC (type)->s->elts[0];
1495
1496       field = TYPE_FIELDS (type);
1497       bot = 0;
1498       top = TYPE_LANG_SPECIFIC (type)->s->len;
1499       while (top - bot > 1)
1500         {
1501           half = (top - bot + 1) >> 1;
1502           field = field_array[bot+half];
1503
1504           if (DECL_NAME (field) == NULL_TREE)
1505             {
1506               /* Step through all anon unions in linear fashion.  */
1507               while (DECL_NAME (field_array[bot]) == NULL_TREE)
1508                 {
1509                   field = field_array[bot++];
1510                   if (TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
1511                       || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
1512                     {
1513                       tree anon = lookup_field (field, component);
1514
1515                       if (anon)
1516                         return tree_cons (NULL_TREE, field, anon);
1517                     }
1518                 }
1519
1520               /* Entire record is only anon unions.  */
1521               if (bot > top)
1522                 return NULL_TREE;
1523
1524               /* Restart the binary search, with new lower bound.  */
1525               continue;
1526             }
1527
1528           if (DECL_NAME (field) == component)
1529             break;
1530           if (DECL_NAME (field) < component)
1531             bot += half;
1532           else
1533             top = bot + half;
1534         }
1535
1536       if (DECL_NAME (field_array[bot]) == component)
1537         field = field_array[bot];
1538       else if (DECL_NAME (field) != component)
1539         return NULL_TREE;
1540     }
1541   else
1542     {
1543       for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1544         {
1545           if (DECL_NAME (field) == NULL_TREE
1546               && (TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
1547                   || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE))
1548             {
1549               tree anon = lookup_field (field, component);
1550
1551               if (anon)
1552                 return tree_cons (NULL_TREE, field, anon);
1553             }
1554
1555           if (DECL_NAME (field) == component)
1556             break;
1557         }
1558
1559       if (field == NULL_TREE)
1560         return NULL_TREE;
1561     }
1562
1563   return tree_cons (NULL_TREE, field, NULL_TREE);
1564 }
1565
1566 /* Make an expression to refer to the COMPONENT field of
1567    structure or union value DATUM.  COMPONENT is an IDENTIFIER_NODE.  */
1568
1569 tree
1570 build_component_ref (tree datum, tree component)
1571 {
1572   tree type = TREE_TYPE (datum);
1573   enum tree_code code = TREE_CODE (type);
1574   tree field = NULL;
1575   tree ref;
1576
1577   if (!objc_is_public (datum, component))
1578     return error_mark_node;
1579
1580   /* See if there is a field or component with name COMPONENT.  */
1581
1582   if (code == RECORD_TYPE || code == UNION_TYPE)
1583     {
1584       if (!COMPLETE_TYPE_P (type))
1585         {
1586           c_incomplete_type_error (NULL_TREE, type);
1587           return error_mark_node;
1588         }
1589
1590       field = lookup_field (datum, component);
1591
1592       if (!field)
1593         {
1594           error ("%qT has no member named %qE", type, component);
1595           return error_mark_node;
1596         }
1597
1598       /* Chain the COMPONENT_REFs if necessary down to the FIELD.
1599          This might be better solved in future the way the C++ front
1600          end does it - by giving the anonymous entities each a
1601          separate name and type, and then have build_component_ref
1602          recursively call itself.  We can't do that here.  */
1603       do
1604         {
1605           tree subdatum = TREE_VALUE (field);
1606
1607           if (TREE_TYPE (subdatum) == error_mark_node)
1608             return error_mark_node;
1609
1610           ref = build3 (COMPONENT_REF, TREE_TYPE (subdatum), datum, subdatum,
1611                         NULL_TREE);
1612           if (TREE_READONLY (datum) || TREE_READONLY (subdatum))
1613             TREE_READONLY (ref) = 1;
1614           if (TREE_THIS_VOLATILE (datum) || TREE_THIS_VOLATILE (subdatum))
1615             TREE_THIS_VOLATILE (ref) = 1;
1616
1617           if (TREE_DEPRECATED (subdatum))
1618             warn_deprecated_use (subdatum);
1619
1620           datum = ref;
1621
1622           field = TREE_CHAIN (field);
1623         }
1624       while (field);
1625
1626       return ref;
1627     }
1628   else if (code != ERROR_MARK)
1629     error ("request for member %qE in something not a structure or union",
1630            component);
1631
1632   return error_mark_node;
1633 }
1634 \f
1635 /* Given an expression PTR for a pointer, return an expression
1636    for the value pointed to.
1637    ERRORSTRING is the name of the operator to appear in error messages.  */
1638
1639 tree
1640 build_indirect_ref (tree ptr, const char *errorstring)
1641 {
1642   tree pointer = default_conversion (ptr);
1643   tree type = TREE_TYPE (pointer);
1644
1645   if (TREE_CODE (type) == POINTER_TYPE)
1646     {
1647       if (TREE_CODE (pointer) == ADDR_EXPR
1648           && (TREE_TYPE (TREE_OPERAND (pointer, 0))
1649               == TREE_TYPE (type)))
1650         return TREE_OPERAND (pointer, 0);
1651       else
1652         {
1653           tree t = TREE_TYPE (type);
1654           tree ref;
1655
1656           ref = build1 (INDIRECT_REF, t, pointer);
1657
1658           if (!COMPLETE_OR_VOID_TYPE_P (t) && TREE_CODE (t) != ARRAY_TYPE)
1659             {
1660               error ("dereferencing pointer to incomplete type");
1661               return error_mark_node;
1662             }
1663           if (VOID_TYPE_P (t) && skip_evaluation == 0)
1664             warning (0, "dereferencing %<void *%> pointer");
1665
1666           /* We *must* set TREE_READONLY when dereferencing a pointer to const,
1667              so that we get the proper error message if the result is used
1668              to assign to.  Also, &* is supposed to be a no-op.
1669              And ANSI C seems to specify that the type of the result
1670              should be the const type.  */
1671           /* A de-reference of a pointer to const is not a const.  It is valid
1672              to change it via some other pointer.  */
1673           TREE_READONLY (ref) = TYPE_READONLY (t);
1674           TREE_SIDE_EFFECTS (ref)
1675             = TYPE_VOLATILE (t) || TREE_SIDE_EFFECTS (pointer);
1676           TREE_THIS_VOLATILE (ref) = TYPE_VOLATILE (t);
1677           return ref;
1678         }
1679     }
1680   else if (TREE_CODE (pointer) != ERROR_MARK)
1681     error ("invalid type argument of %qs", errorstring);
1682   return error_mark_node;
1683 }
1684
1685 /* This handles expressions of the form "a[i]", which denotes
1686    an array reference.
1687
1688    This is logically equivalent in C to *(a+i), but we may do it differently.
1689    If A is a variable or a member, we generate a primitive ARRAY_REF.
1690    This avoids forcing the array out of registers, and can work on
1691    arrays that are not lvalues (for example, members of structures returned
1692    by functions).  */
1693
1694 tree
1695 build_array_ref (tree array, tree index)
1696 {
1697   bool swapped = false;
1698   if (TREE_TYPE (array) == error_mark_node
1699       || TREE_TYPE (index) == error_mark_node)
1700     return error_mark_node;
1701
1702   if (TREE_CODE (TREE_TYPE (array)) != ARRAY_TYPE
1703       && TREE_CODE (TREE_TYPE (array)) != POINTER_TYPE)
1704     {
1705       tree temp;
1706       if (TREE_CODE (TREE_TYPE (index)) != ARRAY_TYPE
1707           && TREE_CODE (TREE_TYPE (index)) != POINTER_TYPE)
1708         {
1709           error ("subscripted value is neither array nor pointer");
1710           return error_mark_node;
1711         }
1712       temp = array;
1713       array = index;
1714       index = temp;
1715       swapped = true;
1716     }
1717
1718   if (!INTEGRAL_TYPE_P (TREE_TYPE (index)))
1719     {
1720       error ("array subscript is not an integer");
1721       return error_mark_node;
1722     }
1723
1724   if (TREE_CODE (TREE_TYPE (TREE_TYPE (array))) == FUNCTION_TYPE)
1725     {
1726       error ("subscripted value is pointer to function");
1727       return error_mark_node;
1728     }
1729
1730   /* Subscripting with type char is likely to lose on a machine where
1731      chars are signed.  So warn on any machine, but optionally.  Don't
1732      warn for unsigned char since that type is safe.  Don't warn for
1733      signed char because anyone who uses that must have done so
1734      deliberately.  ??? Existing practice has also been to warn only
1735      when the char index is syntactically the index, not for
1736      char[array].  */
1737   if (!swapped
1738       && TYPE_MAIN_VARIANT (TREE_TYPE (index)) == char_type_node)
1739     warning (OPT_Wchar_subscripts, "array subscript has type %<char%>");
1740
1741   /* Apply default promotions *after* noticing character types.  */
1742   index = default_conversion (index);
1743
1744   gcc_assert (TREE_CODE (TREE_TYPE (index)) == INTEGER_TYPE);
1745
1746   if (TREE_CODE (TREE_TYPE (array)) == ARRAY_TYPE)
1747     {
1748       tree rval, type;
1749
1750       /* An array that is indexed by a non-constant
1751          cannot be stored in a register; we must be able to do
1752          address arithmetic on its address.
1753          Likewise an array of elements of variable size.  */
1754       if (TREE_CODE (index) != INTEGER_CST
1755           || (COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (array)))
1756               && TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (array)))) != INTEGER_CST))
1757         {
1758           if (!c_mark_addressable (array))
1759             return error_mark_node;
1760         }
1761       /* An array that is indexed by a constant value which is not within
1762          the array bounds cannot be stored in a register either; because we
1763          would get a crash in store_bit_field/extract_bit_field when trying
1764          to access a non-existent part of the register.  */
1765       if (TREE_CODE (index) == INTEGER_CST
1766           && TYPE_DOMAIN (TREE_TYPE (array))
1767           && !int_fits_type_p (index, TYPE_DOMAIN (TREE_TYPE (array))))
1768         {
1769           if (!c_mark_addressable (array))
1770             return error_mark_node;
1771         }
1772
1773       if (pedantic)
1774         {
1775           tree foo = array;
1776           while (TREE_CODE (foo) == COMPONENT_REF)
1777             foo = TREE_OPERAND (foo, 0);
1778           if (TREE_CODE (foo) == VAR_DECL && C_DECL_REGISTER (foo))
1779             pedwarn ("ISO C forbids subscripting %<register%> array");
1780           else if (!flag_isoc99 && !lvalue_p (foo))
1781             pedwarn ("ISO C90 forbids subscripting non-lvalue array");
1782         }
1783
1784       type = TREE_TYPE (TREE_TYPE (array));
1785       if (TREE_CODE (type) != ARRAY_TYPE)
1786         type = TYPE_MAIN_VARIANT (type);
1787       rval = build4 (ARRAY_REF, type, array, index, NULL_TREE, NULL_TREE);
1788       /* Array ref is const/volatile if the array elements are
1789          or if the array is.  */
1790       TREE_READONLY (rval)
1791         |= (TYPE_READONLY (TREE_TYPE (TREE_TYPE (array)))
1792             | TREE_READONLY (array));
1793       TREE_SIDE_EFFECTS (rval)
1794         |= (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (array)))
1795             | TREE_SIDE_EFFECTS (array));
1796       TREE_THIS_VOLATILE (rval)
1797         |= (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (array)))
1798             /* This was added by rms on 16 Nov 91.
1799                It fixes  vol struct foo *a;  a->elts[1]
1800                in an inline function.
1801                Hope it doesn't break something else.  */
1802             | TREE_THIS_VOLATILE (array));
1803       return require_complete_type (fold (rval));
1804     }
1805   else
1806     {
1807       tree ar = default_conversion (array);
1808
1809       if (ar == error_mark_node)
1810         return ar;
1811
1812       gcc_assert (TREE_CODE (TREE_TYPE (ar)) == POINTER_TYPE);
1813       gcc_assert (TREE_CODE (TREE_TYPE (TREE_TYPE (ar))) != FUNCTION_TYPE);
1814
1815       return build_indirect_ref (build_binary_op (PLUS_EXPR, ar, index, 0),
1816                                  "array indexing");
1817     }
1818 }
1819 \f
1820 /* Build an external reference to identifier ID.  FUN indicates
1821    whether this will be used for a function call.  LOC is the source
1822    location of the identifier.  */
1823 tree
1824 build_external_ref (tree id, int fun, location_t loc)
1825 {
1826   tree ref;
1827   tree decl = lookup_name (id);
1828
1829   /* In Objective-C, an instance variable (ivar) may be preferred to
1830      whatever lookup_name() found.  */
1831   decl = objc_lookup_ivar (decl, id);
1832
1833   if (decl && decl != error_mark_node)
1834     ref = decl;
1835   else if (fun)
1836     /* Implicit function declaration.  */
1837     ref = implicitly_declare (id);
1838   else if (decl == error_mark_node)
1839     /* Don't complain about something that's already been
1840        complained about.  */
1841     return error_mark_node;
1842   else
1843     {
1844       undeclared_variable (id, loc);
1845       return error_mark_node;
1846     }
1847
1848   if (TREE_TYPE (ref) == error_mark_node)
1849     return error_mark_node;
1850
1851   if (TREE_DEPRECATED (ref))
1852     warn_deprecated_use (ref);
1853
1854   if (!skip_evaluation)
1855     assemble_external (ref);
1856   TREE_USED (ref) = 1;
1857
1858   if (TREE_CODE (ref) == FUNCTION_DECL && !in_alignof)
1859     {
1860       if (!in_sizeof && !in_typeof)
1861         C_DECL_USED (ref) = 1;
1862       else if (DECL_INITIAL (ref) == 0
1863                && DECL_EXTERNAL (ref)
1864                && !TREE_PUBLIC (ref))
1865         record_maybe_used_decl (ref);
1866     }
1867
1868   if (TREE_CODE (ref) == CONST_DECL)
1869     {
1870       ref = DECL_INITIAL (ref);
1871       TREE_CONSTANT (ref) = 1;
1872       TREE_INVARIANT (ref) = 1;
1873     }
1874   else if (current_function_decl != 0
1875            && !DECL_FILE_SCOPE_P (current_function_decl)
1876            && (TREE_CODE (ref) == VAR_DECL
1877                || TREE_CODE (ref) == PARM_DECL
1878                || TREE_CODE (ref) == FUNCTION_DECL))
1879     {
1880       tree context = decl_function_context (ref);
1881
1882       if (context != 0 && context != current_function_decl)
1883         DECL_NONLOCAL (ref) = 1;
1884     }
1885
1886   return ref;
1887 }
1888
1889 /* Record details of decls possibly used inside sizeof or typeof.  */
1890 struct maybe_used_decl
1891 {
1892   /* The decl.  */
1893   tree decl;
1894   /* The level seen at (in_sizeof + in_typeof).  */
1895   int level;
1896   /* The next one at this level or above, or NULL.  */
1897   struct maybe_used_decl *next;
1898 };
1899
1900 static struct maybe_used_decl *maybe_used_decls;
1901
1902 /* Record that DECL, an undefined static function reference seen
1903    inside sizeof or typeof, might be used if the operand of sizeof is
1904    a VLA type or the operand of typeof is a variably modified
1905    type.  */
1906
1907 static void
1908 record_maybe_used_decl (tree decl)
1909 {
1910   struct maybe_used_decl *t = XOBNEW (&parser_obstack, struct maybe_used_decl);
1911   t->decl = decl;
1912   t->level = in_sizeof + in_typeof;
1913   t->next = maybe_used_decls;
1914   maybe_used_decls = t;
1915 }
1916
1917 /* Pop the stack of decls possibly used inside sizeof or typeof.  If
1918    USED is false, just discard them.  If it is true, mark them used
1919    (if no longer inside sizeof or typeof) or move them to the next
1920    level up (if still inside sizeof or typeof).  */
1921
1922 void
1923 pop_maybe_used (bool used)
1924 {
1925   struct maybe_used_decl *p = maybe_used_decls;
1926   int cur_level = in_sizeof + in_typeof;
1927   while (p && p->level > cur_level)
1928     {
1929       if (used)
1930         {
1931           if (cur_level == 0)
1932             C_DECL_USED (p->decl) = 1;
1933           else
1934             p->level = cur_level;
1935         }
1936       p = p->next;
1937     }
1938   if (!used || cur_level == 0)
1939     maybe_used_decls = p;
1940 }
1941
1942 /* Return the result of sizeof applied to EXPR.  */
1943
1944 struct c_expr
1945 c_expr_sizeof_expr (struct c_expr expr)
1946 {
1947   struct c_expr ret;
1948   if (expr.value == error_mark_node)
1949     {
1950       ret.value = error_mark_node;
1951       ret.original_code = ERROR_MARK;
1952       pop_maybe_used (false);
1953     }
1954   else
1955     {
1956       ret.value = c_sizeof (TREE_TYPE (expr.value));
1957       ret.original_code = ERROR_MARK;
1958       pop_maybe_used (C_TYPE_VARIABLE_SIZE (TREE_TYPE (expr.value)));
1959     }
1960   return ret;
1961 }
1962
1963 /* Return the result of sizeof applied to T, a structure for the type
1964    name passed to sizeof (rather than the type itself).  */
1965
1966 struct c_expr
1967 c_expr_sizeof_type (struct c_type_name *t)
1968 {
1969   tree type;
1970   struct c_expr ret;
1971   type = groktypename (t);
1972   ret.value = c_sizeof (type);
1973   ret.original_code = ERROR_MARK;
1974   pop_maybe_used (C_TYPE_VARIABLE_SIZE (type));
1975   return ret;
1976 }
1977
1978 /* Build a function call to function FUNCTION with parameters PARAMS.
1979    PARAMS is a list--a chain of TREE_LIST nodes--in which the
1980    TREE_VALUE of each node is a parameter-expression.
1981    FUNCTION's data type may be a function type or a pointer-to-function.  */
1982
1983 tree
1984 build_function_call (tree function, tree params)
1985 {
1986   tree fntype, fundecl = 0;
1987   tree coerced_params;
1988   tree name = NULL_TREE, result;
1989   tree tem;
1990
1991   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
1992   STRIP_TYPE_NOPS (function);
1993
1994   /* Convert anything with function type to a pointer-to-function.  */
1995   if (TREE_CODE (function) == FUNCTION_DECL)
1996     {
1997       /* Implement type-directed function overloading for builtins.
1998          resolve_overloaded_builtin and targetm.resolve_overloaded_builtin
1999          handle all the type checking.  The result is a complete expression
2000          that implements this function call.  */
2001       tem = resolve_overloaded_builtin (function, params);
2002       if (tem)
2003         return tem;
2004
2005       name = DECL_NAME (function);
2006       fundecl = function;
2007     }
2008   if (TREE_CODE (TREE_TYPE (function)) == FUNCTION_TYPE)
2009     function = function_to_pointer_conversion (function);
2010
2011   /* For Objective-C, convert any calls via a cast to OBJC_TYPE_REF
2012      expressions, like those used for ObjC messenger dispatches.  */
2013   function = objc_rewrite_function_call (function, params);
2014
2015   fntype = TREE_TYPE (function);
2016
2017   if (TREE_CODE (fntype) == ERROR_MARK)
2018     return error_mark_node;
2019
2020   if (!(TREE_CODE (fntype) == POINTER_TYPE
2021         && TREE_CODE (TREE_TYPE (fntype)) == FUNCTION_TYPE))
2022     {
2023       error ("called object %qE is not a function", function);
2024       return error_mark_node;
2025     }
2026
2027   if (fundecl && TREE_THIS_VOLATILE (fundecl))
2028     current_function_returns_abnormally = 1;
2029
2030   /* fntype now gets the type of function pointed to.  */
2031   fntype = TREE_TYPE (fntype);
2032
2033   /* Check that the function is called through a compatible prototype.
2034      If it is not, replace the call by a trap, wrapped up in a compound
2035      expression if necessary.  This has the nice side-effect to prevent
2036      the tree-inliner from generating invalid assignment trees which may
2037      blow up in the RTL expander later.  */
2038   if (TREE_CODE (function) == NOP_EXPR
2039       && TREE_CODE (tem = TREE_OPERAND (function, 0)) == ADDR_EXPR
2040       && TREE_CODE (tem = TREE_OPERAND (tem, 0)) == FUNCTION_DECL
2041       && !comptypes (fntype, TREE_TYPE (tem)))
2042     {
2043       tree return_type = TREE_TYPE (fntype);
2044       tree trap = build_function_call (built_in_decls[BUILT_IN_TRAP],
2045                                        NULL_TREE);
2046
2047       /* This situation leads to run-time undefined behavior.  We can't,
2048          therefore, simply error unless we can prove that all possible
2049          executions of the program must execute the code.  */
2050       warning (0, "function called through a non-compatible type");
2051
2052       /* We can, however, treat "undefined" any way we please.
2053          Call abort to encourage the user to fix the program.  */
2054       inform ("if this code is reached, the program will abort");
2055
2056       if (VOID_TYPE_P (return_type))
2057         return trap;
2058       else
2059         {
2060           tree rhs;
2061
2062           if (AGGREGATE_TYPE_P (return_type))
2063             rhs = build_compound_literal (return_type,
2064                                           build_constructor (return_type,
2065                                                              NULL_TREE));
2066           else
2067             rhs = fold_build1 (NOP_EXPR, return_type, integer_zero_node);
2068
2069           return build2 (COMPOUND_EXPR, return_type, trap, rhs);
2070         }
2071     }
2072
2073   /* Convert the parameters to the types declared in the
2074      function prototype, or apply default promotions.  */
2075
2076   coerced_params
2077     = convert_arguments (TYPE_ARG_TYPES (fntype), params, function, fundecl);
2078
2079   if (coerced_params == error_mark_node)
2080     return error_mark_node;
2081
2082   /* Check that the arguments to the function are valid.  */
2083
2084   check_function_arguments (TYPE_ATTRIBUTES (fntype), coerced_params,
2085                             TYPE_ARG_TYPES (fntype));
2086
2087   result = build3 (CALL_EXPR, TREE_TYPE (fntype),
2088                    function, coerced_params, NULL_TREE);
2089   TREE_SIDE_EFFECTS (result) = 1;
2090
2091   if (require_constant_value)
2092     {
2093       result = fold_initializer (result);
2094
2095       if (TREE_CONSTANT (result)
2096           && (name == NULL_TREE
2097               || strncmp (IDENTIFIER_POINTER (name), "__builtin_", 10) != 0))
2098         pedwarn_init ("initializer element is not constant");
2099     }
2100   else
2101     result = fold (result);
2102
2103   if (VOID_TYPE_P (TREE_TYPE (result)))
2104     return result;
2105   return require_complete_type (result);
2106 }
2107 \f
2108 /* Convert the argument expressions in the list VALUES
2109    to the types in the list TYPELIST.  The result is a list of converted
2110    argument expressions, unless there are too few arguments in which
2111    case it is error_mark_node.
2112
2113    If TYPELIST is exhausted, or when an element has NULL as its type,
2114    perform the default conversions.
2115
2116    PARMLIST is the chain of parm decls for the function being called.
2117    It may be 0, if that info is not available.
2118    It is used only for generating error messages.
2119
2120    FUNCTION is a tree for the called function.  It is used only for
2121    error messages, where it is formatted with %qE.
2122
2123    This is also where warnings about wrong number of args are generated.
2124
2125    Both VALUES and the returned value are chains of TREE_LIST nodes
2126    with the elements of the list in the TREE_VALUE slots of those nodes.  */
2127
2128 static tree
2129 convert_arguments (tree typelist, tree values, tree function, tree fundecl)
2130 {
2131   tree typetail, valtail;
2132   tree result = NULL;
2133   int parmnum;
2134   tree selector;
2135
2136   /* Change pointer to function to the function itself for
2137      diagnostics.  */
2138   if (TREE_CODE (function) == ADDR_EXPR
2139       && TREE_CODE (TREE_OPERAND (function, 0)) == FUNCTION_DECL)
2140     function = TREE_OPERAND (function, 0);
2141
2142   /* Handle an ObjC selector specially for diagnostics.  */
2143   selector = objc_message_selector ();
2144
2145   /* Scan the given expressions and types, producing individual
2146      converted arguments and pushing them on RESULT in reverse order.  */
2147
2148   for (valtail = values, typetail = typelist, parmnum = 0;
2149        valtail;
2150        valtail = TREE_CHAIN (valtail), parmnum++)
2151     {
2152       tree type = typetail ? TREE_VALUE (typetail) : 0;
2153       tree val = TREE_VALUE (valtail);
2154       tree rname = function;
2155       int argnum = parmnum + 1;
2156       const char *invalid_func_diag;
2157
2158       if (type == void_type_node)
2159         {
2160           error ("too many arguments to function %qE", function);
2161           break;
2162         }
2163
2164       if (selector && argnum > 2)
2165         {
2166           rname = selector;
2167           argnum -= 2;
2168         }
2169
2170       STRIP_TYPE_NOPS (val);
2171
2172       val = require_complete_type (val);
2173
2174       if (type != 0)
2175         {
2176           /* Formal parm type is specified by a function prototype.  */
2177           tree parmval;
2178
2179           if (type == error_mark_node || !COMPLETE_TYPE_P (type))
2180             {
2181               error ("type of formal parameter %d is incomplete", parmnum + 1);
2182               parmval = val;
2183             }
2184           else
2185             {
2186               /* Optionally warn about conversions that
2187                  differ from the default conversions.  */
2188               if (warn_conversion || warn_traditional)
2189                 {
2190                   unsigned int formal_prec = TYPE_PRECISION (type);
2191
2192                   if (INTEGRAL_TYPE_P (type)
2193                       && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
2194                     warning (0, "passing argument %d of %qE as integer "
2195                              "rather than floating due to prototype",
2196                              argnum, rname);
2197                   if (INTEGRAL_TYPE_P (type)
2198                       && TREE_CODE (TREE_TYPE (val)) == COMPLEX_TYPE)
2199                     warning (0, "passing argument %d of %qE as integer "
2200                              "rather than complex due to prototype",
2201                              argnum, rname);
2202                   else if (TREE_CODE (type) == COMPLEX_TYPE
2203                            && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
2204                     warning (0, "passing argument %d of %qE as complex "
2205                              "rather than floating due to prototype",
2206                              argnum, rname);
2207                   else if (TREE_CODE (type) == REAL_TYPE
2208                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2209                     warning (0, "passing argument %d of %qE as floating "
2210                              "rather than integer due to prototype",
2211                              argnum, rname);
2212                   else if (TREE_CODE (type) == COMPLEX_TYPE
2213                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2214                     warning (0, "passing argument %d of %qE as complex "
2215                              "rather than integer due to prototype",
2216                              argnum, rname);
2217                   else if (TREE_CODE (type) == REAL_TYPE
2218                            && TREE_CODE (TREE_TYPE (val)) == COMPLEX_TYPE)
2219                     warning (0, "passing argument %d of %qE as floating "
2220                              "rather than complex due to prototype",
2221                              argnum, rname);
2222                   /* ??? At some point, messages should be written about
2223                      conversions between complex types, but that's too messy
2224                      to do now.  */
2225                   else if (TREE_CODE (type) == REAL_TYPE
2226                            && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
2227                     {
2228                       /* Warn if any argument is passed as `float',
2229                          since without a prototype it would be `double'.  */
2230                       if (formal_prec == TYPE_PRECISION (float_type_node))
2231                         warning (0, "passing argument %d of %qE as %<float%> "
2232                                  "rather than %<double%> due to prototype",
2233                                  argnum, rname);
2234                     }
2235                   /* Detect integer changing in width or signedness.
2236                      These warnings are only activated with
2237                      -Wconversion, not with -Wtraditional.  */
2238                   else if (warn_conversion && INTEGRAL_TYPE_P (type)
2239                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2240                     {
2241                       tree would_have_been = default_conversion (val);
2242                       tree type1 = TREE_TYPE (would_have_been);
2243
2244                       if (TREE_CODE (type) == ENUMERAL_TYPE
2245                           && (TYPE_MAIN_VARIANT (type)
2246                               == TYPE_MAIN_VARIANT (TREE_TYPE (val))))
2247                         /* No warning if function asks for enum
2248                            and the actual arg is that enum type.  */
2249                         ;
2250                       else if (formal_prec != TYPE_PRECISION (type1))
2251                         warning (OPT_Wconversion, "passing argument %d of %qE "
2252                                  "with different width due to prototype",
2253                                  argnum, rname);
2254                       else if (TYPE_UNSIGNED (type) == TYPE_UNSIGNED (type1))
2255                         ;
2256                       /* Don't complain if the formal parameter type
2257                          is an enum, because we can't tell now whether
2258                          the value was an enum--even the same enum.  */
2259                       else if (TREE_CODE (type) == ENUMERAL_TYPE)
2260                         ;
2261                       else if (TREE_CODE (val) == INTEGER_CST
2262                                && int_fits_type_p (val, type))
2263                         /* Change in signedness doesn't matter
2264                            if a constant value is unaffected.  */
2265                         ;
2266                       /* If the value is extended from a narrower
2267                          unsigned type, it doesn't matter whether we
2268                          pass it as signed or unsigned; the value
2269                          certainly is the same either way.  */
2270                       else if (TYPE_PRECISION (TREE_TYPE (val)) < TYPE_PRECISION (type)
2271                                && TYPE_UNSIGNED (TREE_TYPE (val)))
2272                         ;
2273                       else if (TYPE_UNSIGNED (type))
2274                         warning (OPT_Wconversion, "passing argument %d of %qE "
2275                                  "as unsigned due to prototype",
2276                                  argnum, rname);
2277                       else
2278                         warning (OPT_Wconversion, "passing argument %d of %qE "
2279                                  "as signed due to prototype", argnum, rname);
2280                     }
2281                 }
2282
2283               parmval = convert_for_assignment (type, val, ic_argpass,
2284                                                 fundecl, function,
2285                                                 parmnum + 1);
2286
2287               if (targetm.calls.promote_prototypes (fundecl ? TREE_TYPE (fundecl) : 0)
2288                   && INTEGRAL_TYPE_P (type)
2289                   && (TYPE_PRECISION (type) < TYPE_PRECISION (integer_type_node)))
2290                 parmval = default_conversion (parmval);
2291             }
2292           result = tree_cons (NULL_TREE, parmval, result);
2293         }
2294       else if (TREE_CODE (TREE_TYPE (val)) == REAL_TYPE
2295                && (TYPE_PRECISION (TREE_TYPE (val))
2296                    < TYPE_PRECISION (double_type_node)))
2297         /* Convert `float' to `double'.  */
2298         result = tree_cons (NULL_TREE, convert (double_type_node, val), result);
2299       else if ((invalid_func_diag =
2300                 targetm.calls.invalid_arg_for_unprototyped_fn (typelist, fundecl, val)))
2301         {
2302           error (invalid_func_diag);
2303           return error_mark_node;
2304         }
2305       else
2306         /* Convert `short' and `char' to full-size `int'.  */
2307         result = tree_cons (NULL_TREE, default_conversion (val), result);
2308
2309       if (typetail)
2310         typetail = TREE_CHAIN (typetail);
2311     }
2312
2313   if (typetail != 0 && TREE_VALUE (typetail) != void_type_node)
2314     {
2315       error ("too few arguments to function %qE", function);
2316       return error_mark_node;
2317     }
2318
2319   return nreverse (result);
2320 }
2321 \f
2322 /* This is the entry point used by the parser to build unary operators
2323    in the input.  CODE, a tree_code, specifies the unary operator, and
2324    ARG is the operand.  For unary plus, the C parser currently uses
2325    CONVERT_EXPR for code.  */
2326
2327 struct c_expr
2328 parser_build_unary_op (enum tree_code code, struct c_expr arg)
2329 {
2330   struct c_expr result;
2331
2332   result.original_code = ERROR_MARK;
2333   result.value = build_unary_op (code, arg.value, 0);
2334   overflow_warning (result.value);
2335   return result;
2336 }
2337
2338 /* This is the entry point used by the parser to build binary operators
2339    in the input.  CODE, a tree_code, specifies the binary operator, and
2340    ARG1 and ARG2 are the operands.  In addition to constructing the
2341    expression, we check for operands that were written with other binary
2342    operators in a way that is likely to confuse the user.  */
2343
2344 struct c_expr
2345 parser_build_binary_op (enum tree_code code, struct c_expr arg1,
2346                         struct c_expr arg2)
2347 {
2348   struct c_expr result;
2349
2350   enum tree_code code1 = arg1.original_code;
2351   enum tree_code code2 = arg2.original_code;
2352
2353   result.value = build_binary_op (code, arg1.value, arg2.value, 1);
2354   result.original_code = code;
2355
2356   if (TREE_CODE (result.value) == ERROR_MARK)
2357     return result;
2358
2359   /* Check for cases such as x+y<<z which users are likely
2360      to misinterpret.  */
2361   if (warn_parentheses)
2362     {
2363       if (code == LSHIFT_EXPR || code == RSHIFT_EXPR)
2364         {
2365           if (code1 == PLUS_EXPR || code1 == MINUS_EXPR
2366               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2367             warning (0, "suggest parentheses around + or - inside shift");
2368         }
2369
2370       if (code == TRUTH_ORIF_EXPR)
2371         {
2372           if (code1 == TRUTH_ANDIF_EXPR
2373               || code2 == TRUTH_ANDIF_EXPR)
2374             warning (0, "suggest parentheses around && within ||");
2375         }
2376
2377       if (code == BIT_IOR_EXPR)
2378         {
2379           if (code1 == BIT_AND_EXPR || code1 == BIT_XOR_EXPR
2380               || code1 == PLUS_EXPR || code1 == MINUS_EXPR
2381               || code2 == BIT_AND_EXPR || code2 == BIT_XOR_EXPR
2382               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2383             warning (0, "suggest parentheses around arithmetic 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
2390       if (code == BIT_XOR_EXPR)
2391         {
2392           if (code1 == BIT_AND_EXPR
2393               || code1 == PLUS_EXPR || code1 == MINUS_EXPR
2394               || code2 == BIT_AND_EXPR
2395               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2396             warning (0, "suggest parentheses around arithmetic in operand of ^");
2397           /* Check cases like x^y==z */
2398           if (TREE_CODE_CLASS (code1) == tcc_comparison
2399               || TREE_CODE_CLASS (code2) == tcc_comparison)
2400             warning (0, "suggest parentheses around comparison in operand of ^");
2401         }
2402
2403       if (code == BIT_AND_EXPR)
2404         {
2405           if (code1 == PLUS_EXPR || code1 == MINUS_EXPR
2406               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2407             warning (0, "suggest parentheses around + or - in operand of &");
2408           /* Check cases like x&y==z */
2409           if (TREE_CODE_CLASS (code1) == tcc_comparison
2410               || TREE_CODE_CLASS (code2) == tcc_comparison)
2411             warning (0, "suggest parentheses around comparison in operand of &");
2412         }
2413       /* Similarly, check for cases like 1<=i<=10 that are probably errors.  */
2414       if (TREE_CODE_CLASS (code) == tcc_comparison
2415           && (TREE_CODE_CLASS (code1) == tcc_comparison
2416               || TREE_CODE_CLASS (code2) == tcc_comparison))
2417         warning (0, "comparisons like X<=Y<=Z do not have their mathematical meaning");
2418
2419     }
2420
2421   unsigned_conversion_warning (result.value, arg1.value);
2422   unsigned_conversion_warning (result.value, arg2.value);
2423   overflow_warning (result.value);
2424
2425   return result;
2426 }
2427 \f
2428 /* Return a tree for the difference of pointers OP0 and OP1.
2429    The resulting tree has type int.  */
2430
2431 static tree
2432 pointer_diff (tree op0, tree op1)
2433 {
2434   tree restype = ptrdiff_type_node;
2435
2436   tree target_type = TREE_TYPE (TREE_TYPE (op0));
2437   tree con0, con1, lit0, lit1;
2438   tree orig_op1 = op1;
2439
2440   if (pedantic || warn_pointer_arith)
2441     {
2442       if (TREE_CODE (target_type) == VOID_TYPE)
2443         pedwarn ("pointer of type %<void *%> used in subtraction");
2444       if (TREE_CODE (target_type) == FUNCTION_TYPE)
2445         pedwarn ("pointer to a function used in subtraction");
2446     }
2447
2448   /* If the conversion to ptrdiff_type does anything like widening or
2449      converting a partial to an integral mode, we get a convert_expression
2450      that is in the way to do any simplifications.
2451      (fold-const.c doesn't know that the extra bits won't be needed.
2452      split_tree uses STRIP_SIGN_NOPS, which leaves conversions to a
2453      different mode in place.)
2454      So first try to find a common term here 'by hand'; we want to cover
2455      at least the cases that occur in legal static initializers.  */
2456   con0 = TREE_CODE (op0) == NOP_EXPR ? TREE_OPERAND (op0, 0) : op0;
2457   con1 = TREE_CODE (op1) == NOP_EXPR ? TREE_OPERAND (op1, 0) : op1;
2458
2459   if (TREE_CODE (con0) == PLUS_EXPR)
2460     {
2461       lit0 = TREE_OPERAND (con0, 1);
2462       con0 = TREE_OPERAND (con0, 0);
2463     }
2464   else
2465     lit0 = integer_zero_node;
2466
2467   if (TREE_CODE (con1) == PLUS_EXPR)
2468     {
2469       lit1 = TREE_OPERAND (con1, 1);
2470       con1 = TREE_OPERAND (con1, 0);
2471     }
2472   else
2473     lit1 = integer_zero_node;
2474
2475   if (operand_equal_p (con0, con1, 0))
2476     {
2477       op0 = lit0;
2478       op1 = lit1;
2479     }
2480
2481
2482   /* First do the subtraction as integers;
2483      then drop through to build the divide operator.
2484      Do not do default conversions on the minus operator
2485      in case restype is a short type.  */
2486
2487   op0 = build_binary_op (MINUS_EXPR, convert (restype, op0),
2488                          convert (restype, op1), 0);
2489   /* This generates an error if op1 is pointer to incomplete type.  */
2490   if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (TREE_TYPE (orig_op1))))
2491     error ("arithmetic on pointer to an incomplete type");
2492
2493   /* This generates an error if op0 is pointer to incomplete type.  */
2494   op1 = c_size_in_bytes (target_type);
2495
2496   /* Divide by the size, in easiest possible way.  */
2497   return fold_build2 (EXACT_DIV_EXPR, restype, op0, convert (restype, op1));
2498 }
2499 \f
2500 /* Construct and perhaps optimize a tree representation
2501    for a unary operation.  CODE, a tree_code, specifies the operation
2502    and XARG is the operand.
2503    For any CODE other than ADDR_EXPR, FLAG nonzero suppresses
2504    the default promotions (such as from short to int).
2505    For ADDR_EXPR, the default promotions are not applied; FLAG nonzero
2506    allows non-lvalues; this is only used to handle conversion of non-lvalue
2507    arrays to pointers in C99.  */
2508
2509 tree
2510 build_unary_op (enum tree_code code, tree xarg, int flag)
2511 {
2512   /* No default_conversion here.  It causes trouble for ADDR_EXPR.  */
2513   tree arg = xarg;
2514   tree argtype = 0;
2515   enum tree_code typecode = TREE_CODE (TREE_TYPE (arg));
2516   tree val;
2517   int noconvert = flag;
2518   const char *invalid_op_diag;
2519
2520   if (typecode == ERROR_MARK)
2521     return error_mark_node;
2522   if (typecode == ENUMERAL_TYPE || typecode == BOOLEAN_TYPE)
2523     typecode = INTEGER_TYPE;
2524
2525   if ((invalid_op_diag
2526        = targetm.invalid_unary_op (code, TREE_TYPE (xarg))))
2527     {
2528       error (invalid_op_diag);
2529       return error_mark_node;
2530     }
2531
2532   switch (code)
2533     {
2534     case CONVERT_EXPR:
2535       /* This is used for unary plus, because a CONVERT_EXPR
2536          is enough to prevent anybody from looking inside for
2537          associativity, but won't generate any code.  */
2538       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2539             || typecode == COMPLEX_TYPE
2540             || typecode == VECTOR_TYPE))
2541         {
2542           error ("wrong type argument to unary plus");
2543           return error_mark_node;
2544         }
2545       else if (!noconvert)
2546         arg = default_conversion (arg);
2547       arg = non_lvalue (arg);
2548       break;
2549
2550     case NEGATE_EXPR:
2551       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2552             || typecode == COMPLEX_TYPE
2553             || typecode == VECTOR_TYPE))
2554         {
2555           error ("wrong type argument to unary minus");
2556           return error_mark_node;
2557         }
2558       else if (!noconvert)
2559         arg = default_conversion (arg);
2560       break;
2561
2562     case BIT_NOT_EXPR:
2563       if (typecode == INTEGER_TYPE || typecode == VECTOR_TYPE)
2564         {
2565           if (!noconvert)
2566             arg = default_conversion (arg);
2567         }
2568       else if (typecode == COMPLEX_TYPE)
2569         {
2570           code = CONJ_EXPR;
2571           if (pedantic)
2572             pedwarn ("ISO C does not support %<~%> for complex conjugation");
2573           if (!noconvert)
2574             arg = default_conversion (arg);
2575         }
2576       else
2577         {
2578           error ("wrong type argument to bit-complement");
2579           return error_mark_node;
2580         }
2581       break;
2582
2583     case ABS_EXPR:
2584       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE))
2585         {
2586           error ("wrong type argument to abs");
2587           return error_mark_node;
2588         }
2589       else if (!noconvert)
2590         arg = default_conversion (arg);
2591       break;
2592
2593     case CONJ_EXPR:
2594       /* Conjugating a real value is a no-op, but allow it anyway.  */
2595       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2596             || typecode == COMPLEX_TYPE))
2597         {
2598           error ("wrong type argument to conjugation");
2599           return error_mark_node;
2600         }
2601       else if (!noconvert)
2602         arg = default_conversion (arg);
2603       break;
2604
2605     case TRUTH_NOT_EXPR:
2606       if (typecode != INTEGER_TYPE
2607           && typecode != REAL_TYPE && typecode != POINTER_TYPE
2608           && typecode != COMPLEX_TYPE)
2609         {
2610           error ("wrong type argument to unary exclamation mark");
2611           return error_mark_node;
2612         }
2613       arg = c_objc_common_truthvalue_conversion (arg);
2614       return invert_truthvalue (arg);
2615
2616     case NOP_EXPR:
2617       break;
2618
2619     case REALPART_EXPR:
2620       if (TREE_CODE (arg) == COMPLEX_CST)
2621         return TREE_REALPART (arg);
2622       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
2623         return fold_build1 (REALPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg);
2624       else
2625         return arg;
2626
2627     case IMAGPART_EXPR:
2628       if (TREE_CODE (arg) == COMPLEX_CST)
2629         return TREE_IMAGPART (arg);
2630       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
2631         return fold_build1 (IMAGPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg);
2632       else
2633         return convert (TREE_TYPE (arg), integer_zero_node);
2634
2635     case PREINCREMENT_EXPR:
2636     case POSTINCREMENT_EXPR:
2637     case PREDECREMENT_EXPR:
2638     case POSTDECREMENT_EXPR:
2639
2640       /* Increment or decrement the real part of the value,
2641          and don't change the imaginary part.  */
2642       if (typecode == COMPLEX_TYPE)
2643         {
2644           tree real, imag;
2645
2646           if (pedantic)
2647             pedwarn ("ISO C does not support %<++%> and %<--%>"
2648                      " on complex types");
2649
2650           arg = stabilize_reference (arg);
2651           real = build_unary_op (REALPART_EXPR, arg, 1);
2652           imag = build_unary_op (IMAGPART_EXPR, arg, 1);
2653           return build2 (COMPLEX_EXPR, TREE_TYPE (arg),
2654                          build_unary_op (code, real, 1), imag);
2655         }
2656
2657       /* Report invalid types.  */
2658
2659       if (typecode != POINTER_TYPE
2660           && typecode != INTEGER_TYPE && typecode != REAL_TYPE)
2661         {
2662           if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
2663             error ("wrong type argument to increment");
2664           else
2665             error ("wrong type argument to decrement");
2666
2667           return error_mark_node;
2668         }
2669
2670       {
2671         tree inc;
2672         tree result_type = TREE_TYPE (arg);
2673
2674         arg = get_unwidened (arg, 0);
2675         argtype = TREE_TYPE (arg);
2676
2677         /* Compute the increment.  */
2678
2679         if (typecode == POINTER_TYPE)
2680           {
2681             /* If pointer target is an undefined struct,
2682                we just cannot know how to do the arithmetic.  */
2683             if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (result_type)))
2684               {
2685                 if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
2686                   error ("increment of pointer to unknown structure");
2687                 else
2688                   error ("decrement of pointer to unknown structure");
2689               }
2690             else if ((pedantic || warn_pointer_arith)
2691                      && (TREE_CODE (TREE_TYPE (result_type)) == FUNCTION_TYPE
2692                          || TREE_CODE (TREE_TYPE (result_type)) == VOID_TYPE))
2693               {
2694                 if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
2695                   pedwarn ("wrong type argument to increment");
2696                 else
2697                   pedwarn ("wrong type argument to decrement");
2698               }
2699
2700             inc = c_size_in_bytes (TREE_TYPE (result_type));
2701           }
2702         else
2703           inc = integer_one_node;
2704
2705         inc = convert (argtype, inc);
2706
2707         /* Complain about anything else that is not a true lvalue.  */
2708         if (!lvalue_or_else (arg, ((code == PREINCREMENT_EXPR
2709                                     || code == POSTINCREMENT_EXPR)
2710                                    ? lv_increment
2711                                    : lv_decrement)))
2712           return error_mark_node;
2713
2714         /* Report a read-only lvalue.  */
2715         if (TREE_READONLY (arg))
2716           readonly_error (arg,
2717                           ((code == PREINCREMENT_EXPR
2718                             || code == POSTINCREMENT_EXPR)
2719                            ? lv_increment : lv_decrement));
2720
2721         if (TREE_CODE (TREE_TYPE (arg)) == BOOLEAN_TYPE)
2722           val = boolean_increment (code, arg);
2723         else
2724           val = build2 (code, TREE_TYPE (arg), arg, inc);
2725         TREE_SIDE_EFFECTS (val) = 1;
2726         val = convert (result_type, val);
2727         if (TREE_CODE (val) != code)
2728           TREE_NO_WARNING (val) = 1;
2729         return val;
2730       }
2731
2732     case ADDR_EXPR:
2733       /* Note that this operation never does default_conversion.  */
2734
2735       /* Let &* cancel out to simplify resulting code.  */
2736       if (TREE_CODE (arg) == INDIRECT_REF)
2737         {
2738           /* Don't let this be an lvalue.  */
2739           if (lvalue_p (TREE_OPERAND (arg, 0)))
2740             return non_lvalue (TREE_OPERAND (arg, 0));
2741           return TREE_OPERAND (arg, 0);
2742         }
2743
2744       /* For &x[y], return x+y */
2745       if (TREE_CODE (arg) == ARRAY_REF)
2746         {
2747           tree op0 = TREE_OPERAND (arg, 0);
2748           if (!c_mark_addressable (op0))
2749             return error_mark_node;
2750           return build_binary_op (PLUS_EXPR,
2751                                   (TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE
2752                                    ? array_to_pointer_conversion (op0)
2753                                    : op0),
2754                                   TREE_OPERAND (arg, 1), 1);
2755         }
2756
2757       /* Anything not already handled and not a true memory reference
2758          or a non-lvalue array is an error.  */
2759       else if (typecode != FUNCTION_TYPE && !flag
2760                && !lvalue_or_else (arg, lv_addressof))
2761         return error_mark_node;
2762
2763       /* Ordinary case; arg is a COMPONENT_REF or a decl.  */
2764       argtype = TREE_TYPE (arg);
2765
2766       /* If the lvalue is const or volatile, merge that into the type
2767          to which the address will point.  Note that you can't get a
2768          restricted pointer by taking the address of something, so we
2769          only have to deal with `const' and `volatile' here.  */
2770       if ((DECL_P (arg) || REFERENCE_CLASS_P (arg))
2771           && (TREE_READONLY (arg) || TREE_THIS_VOLATILE (arg)))
2772           argtype = c_build_type_variant (argtype,
2773                                           TREE_READONLY (arg),
2774                                           TREE_THIS_VOLATILE (arg));
2775
2776       if (!c_mark_addressable (arg))
2777         return error_mark_node;
2778
2779       gcc_assert (TREE_CODE (arg) != COMPONENT_REF
2780                   || !DECL_C_BIT_FIELD (TREE_OPERAND (arg, 1)));
2781
2782       argtype = build_pointer_type (argtype);
2783
2784       /* ??? Cope with user tricks that amount to offsetof.  Delete this
2785          when we have proper support for integer constant expressions.  */
2786       val = get_base_address (arg);
2787       if (val && TREE_CODE (val) == INDIRECT_REF
2788           && integer_zerop (TREE_OPERAND (val, 0)))
2789         return fold_convert (argtype, fold_offsetof (arg));
2790
2791       val = build1 (ADDR_EXPR, argtype, arg);
2792
2793       return val;
2794
2795     default:
2796       break;
2797     }
2798
2799   if (argtype == 0)
2800     argtype = TREE_TYPE (arg);
2801   val = build1 (code, argtype, arg);
2802   return require_constant_value ? fold_initializer (val) : fold (val);
2803 }
2804
2805 /* Return nonzero if REF is an lvalue valid for this language.
2806    Lvalues can be assigned, unless their type has TYPE_READONLY.
2807    Lvalues can have their address taken, unless they have C_DECL_REGISTER.  */
2808
2809 static int
2810 lvalue_p (tree ref)
2811 {
2812   enum tree_code code = TREE_CODE (ref);
2813
2814   switch (code)
2815     {
2816     case REALPART_EXPR:
2817     case IMAGPART_EXPR:
2818     case COMPONENT_REF:
2819       return lvalue_p (TREE_OPERAND (ref, 0));
2820
2821     case COMPOUND_LITERAL_EXPR:
2822     case STRING_CST:
2823       return 1;
2824
2825     case INDIRECT_REF:
2826     case ARRAY_REF:
2827     case VAR_DECL:
2828     case PARM_DECL:
2829     case RESULT_DECL:
2830     case ERROR_MARK:
2831       return (TREE_CODE (TREE_TYPE (ref)) != FUNCTION_TYPE
2832               && TREE_CODE (TREE_TYPE (ref)) != METHOD_TYPE);
2833
2834     case BIND_EXPR:
2835       return TREE_CODE (TREE_TYPE (ref)) == ARRAY_TYPE;
2836
2837     default:
2838       return 0;
2839     }
2840 }
2841 \f
2842 /* Give an error for storing in something that is 'const'.  */
2843
2844 static void
2845 readonly_error (tree arg, enum lvalue_use use)
2846 {
2847   gcc_assert (use == lv_assign || use == lv_increment || use == lv_decrement);
2848   /* Using this macro rather than (for example) arrays of messages
2849      ensures that all the format strings are checked at compile
2850      time.  */
2851 #define READONLY_MSG(A, I, D) (use == lv_assign                         \
2852                                ? (A)                                    \
2853                                : (use == lv_increment ? (I) : (D)))
2854   if (TREE_CODE (arg) == COMPONENT_REF)
2855     {
2856       if (TYPE_READONLY (TREE_TYPE (TREE_OPERAND (arg, 0))))
2857         readonly_error (TREE_OPERAND (arg, 0), use);
2858       else
2859         error (READONLY_MSG (G_("assignment of read-only member %qD"),
2860                              G_("increment of read-only member %qD"),
2861                              G_("decrement of read-only member %qD")),
2862                TREE_OPERAND (arg, 1));
2863     }
2864   else if (TREE_CODE (arg) == VAR_DECL)
2865     error (READONLY_MSG (G_("assignment of read-only variable %qD"),
2866                          G_("increment of read-only variable %qD"),
2867                          G_("decrement of read-only variable %qD")),
2868            arg);
2869   else
2870     error (READONLY_MSG (G_("assignment of read-only location"),
2871                          G_("increment of read-only location"),
2872                          G_("decrement of read-only location")));
2873 }
2874
2875
2876 /* Return nonzero if REF is an lvalue valid for this language;
2877    otherwise, print an error message and return zero.  USE says
2878    how the lvalue is being used and so selects the error message.  */
2879
2880 static int
2881 lvalue_or_else (tree ref, enum lvalue_use use)
2882 {
2883   int win = lvalue_p (ref);
2884
2885   if (!win)
2886     lvalue_error (use);
2887
2888   return win;
2889 }
2890 \f
2891 /* Mark EXP saying that we need to be able to take the
2892    address of it; it should not be allocated in a register.
2893    Returns true if successful.  */
2894
2895 bool
2896 c_mark_addressable (tree exp)
2897 {
2898   tree x = exp;
2899
2900   while (1)
2901     switch (TREE_CODE (x))
2902       {
2903       case COMPONENT_REF:
2904         if (DECL_C_BIT_FIELD (TREE_OPERAND (x, 1)))
2905           {
2906             error
2907               ("cannot take address of bit-field %qD", TREE_OPERAND (x, 1));
2908             return false;
2909           }
2910
2911         /* ... fall through ...  */
2912
2913       case ADDR_EXPR:
2914       case ARRAY_REF:
2915       case REALPART_EXPR:
2916       case IMAGPART_EXPR:
2917         x = TREE_OPERAND (x, 0);
2918         break;
2919
2920       case COMPOUND_LITERAL_EXPR:
2921       case CONSTRUCTOR:
2922         TREE_ADDRESSABLE (x) = 1;
2923         return true;
2924
2925       case VAR_DECL:
2926       case CONST_DECL:
2927       case PARM_DECL:
2928       case RESULT_DECL:
2929         if (C_DECL_REGISTER (x)
2930             && DECL_NONLOCAL (x))
2931           {
2932             if (TREE_PUBLIC (x) || TREE_STATIC (x) || DECL_EXTERNAL (x))
2933               {
2934                 error
2935                   ("global register variable %qD used in nested function", x);
2936                 return false;
2937               }
2938             pedwarn ("register variable %qD used in nested function", x);
2939           }
2940         else if (C_DECL_REGISTER (x))
2941           {
2942             if (TREE_PUBLIC (x) || TREE_STATIC (x) || DECL_EXTERNAL (x))
2943               error ("address of global register variable %qD requested", x);
2944             else
2945               error ("address of register variable %qD requested", x);
2946             return false;
2947           }
2948
2949         /* drops in */
2950       case FUNCTION_DECL:
2951         TREE_ADDRESSABLE (x) = 1;
2952         /* drops out */
2953       default:
2954         return true;
2955     }
2956 }
2957 \f
2958 /* Build and return a conditional expression IFEXP ? OP1 : OP2.  */
2959
2960 tree
2961 build_conditional_expr (tree ifexp, tree op1, tree op2)
2962 {
2963   tree type1;
2964   tree type2;
2965   enum tree_code code1;
2966   enum tree_code code2;
2967   tree result_type = NULL;
2968   tree orig_op1 = op1, orig_op2 = op2;
2969
2970   /* Promote both alternatives.  */
2971
2972   if (TREE_CODE (TREE_TYPE (op1)) != VOID_TYPE)
2973     op1 = default_conversion (op1);
2974   if (TREE_CODE (TREE_TYPE (op2)) != VOID_TYPE)
2975     op2 = default_conversion (op2);
2976
2977   if (TREE_CODE (ifexp) == ERROR_MARK
2978       || TREE_CODE (TREE_TYPE (op1)) == ERROR_MARK
2979       || TREE_CODE (TREE_TYPE (op2)) == ERROR_MARK)
2980     return error_mark_node;
2981
2982   type1 = TREE_TYPE (op1);
2983   code1 = TREE_CODE (type1);
2984   type2 = TREE_TYPE (op2);
2985   code2 = TREE_CODE (type2);
2986
2987   /* C90 does not permit non-lvalue arrays in conditional expressions.
2988      In C99 they will be pointers by now.  */
2989   if (code1 == ARRAY_TYPE || code2 == ARRAY_TYPE)
2990     {
2991       error ("non-lvalue array in conditional expression");
2992       return error_mark_node;
2993     }
2994
2995   /* Quickly detect the usual case where op1 and op2 have the same type
2996      after promotion.  */
2997   if (TYPE_MAIN_VARIANT (type1) == TYPE_MAIN_VARIANT (type2))
2998     {
2999       if (type1 == type2)
3000         result_type = type1;
3001       else
3002         result_type = TYPE_MAIN_VARIANT (type1);
3003     }
3004   else if ((code1 == INTEGER_TYPE || code1 == REAL_TYPE
3005             || code1 == COMPLEX_TYPE)
3006            && (code2 == INTEGER_TYPE || code2 == REAL_TYPE
3007                || code2 == COMPLEX_TYPE))
3008     {
3009       result_type = c_common_type (type1, type2);
3010
3011       /* If -Wsign-compare, warn here if type1 and type2 have
3012          different signedness.  We'll promote the signed to unsigned
3013          and later code won't know it used to be different.
3014          Do this check on the original types, so that explicit casts
3015          will be considered, but default promotions won't.  */
3016       if (warn_sign_compare && !skip_evaluation)
3017         {
3018           int unsigned_op1 = TYPE_UNSIGNED (TREE_TYPE (orig_op1));
3019           int unsigned_op2 = TYPE_UNSIGNED (TREE_TYPE (orig_op2));
3020
3021           if (unsigned_op1 ^ unsigned_op2)
3022             {
3023               /* Do not warn if the result type is signed, since the
3024                  signed type will only be chosen if it can represent
3025                  all the values of the unsigned type.  */
3026               if (!TYPE_UNSIGNED (result_type))
3027                 /* OK */;
3028               /* Do not warn if the signed quantity is an unsuffixed
3029                  integer literal (or some static constant expression
3030                  involving such literals) and it is non-negative.  */
3031               else if ((unsigned_op2 && tree_expr_nonnegative_p (op1))
3032                        || (unsigned_op1 && tree_expr_nonnegative_p (op2)))
3033                 /* OK */;
3034               else
3035                 warning (0, "signed and unsigned type in conditional expression");
3036             }
3037         }
3038     }
3039   else if (code1 == VOID_TYPE || code2 == VOID_TYPE)
3040     {
3041       if (pedantic && (code1 != VOID_TYPE || code2 != VOID_TYPE))
3042         pedwarn ("ISO C forbids conditional expr with only one void side");
3043       result_type = void_type_node;
3044     }
3045   else if (code1 == POINTER_TYPE && code2 == POINTER_TYPE)
3046     {
3047       if (comp_target_types (type1, type2))
3048         result_type = common_pointer_type (type1, type2);
3049       else if (integer_zerop (op1) && TREE_TYPE (type1) == void_type_node
3050                && TREE_CODE (orig_op1) != NOP_EXPR)
3051         result_type = qualify_type (type2, type1);
3052       else if (integer_zerop (op2) && TREE_TYPE (type2) == void_type_node
3053                && TREE_CODE (orig_op2) != NOP_EXPR)
3054         result_type = qualify_type (type1, type2);
3055       else if (VOID_TYPE_P (TREE_TYPE (type1)))
3056         {
3057           if (pedantic && TREE_CODE (TREE_TYPE (type2)) == FUNCTION_TYPE)
3058             pedwarn ("ISO C forbids conditional expr between "
3059                      "%<void *%> and function pointer");
3060           result_type = build_pointer_type (qualify_type (TREE_TYPE (type1),
3061                                                           TREE_TYPE (type2)));
3062         }
3063       else if (VOID_TYPE_P (TREE_TYPE (type2)))
3064         {
3065           if (pedantic && TREE_CODE (TREE_TYPE (type1)) == FUNCTION_TYPE)
3066             pedwarn ("ISO C forbids conditional expr between "
3067                      "%<void *%> and function pointer");
3068           result_type = build_pointer_type (qualify_type (TREE_TYPE (type2),
3069                                                           TREE_TYPE (type1)));
3070         }
3071       else
3072         {
3073           pedwarn ("pointer type mismatch in conditional expression");
3074           result_type = build_pointer_type (void_type_node);
3075         }
3076     }
3077   else if (code1 == POINTER_TYPE && code2 == INTEGER_TYPE)
3078     {
3079       if (!integer_zerop (op2))
3080         pedwarn ("pointer/integer type mismatch in conditional expression");
3081       else
3082         {
3083           op2 = null_pointer_node;
3084         }
3085       result_type = type1;
3086     }
3087   else if (code2 == POINTER_TYPE && code1 == INTEGER_TYPE)
3088     {
3089       if (!integer_zerop (op1))
3090         pedwarn ("pointer/integer type mismatch in conditional expression");
3091       else
3092         {
3093           op1 = null_pointer_node;
3094         }
3095       result_type = type2;
3096     }
3097
3098   if (!result_type)
3099     {
3100       if (flag_cond_mismatch)
3101         result_type = void_type_node;
3102       else
3103         {
3104           error ("type mismatch in conditional expression");
3105           return error_mark_node;
3106         }
3107     }
3108
3109   /* Merge const and volatile flags of the incoming types.  */
3110   result_type
3111     = build_type_variant (result_type,
3112                           TREE_READONLY (op1) || TREE_READONLY (op2),
3113                           TREE_THIS_VOLATILE (op1) || TREE_THIS_VOLATILE (op2));
3114
3115   if (result_type != TREE_TYPE (op1))
3116     op1 = convert_and_check (result_type, op1);
3117   if (result_type != TREE_TYPE (op2))
3118     op2 = convert_and_check (result_type, op2);
3119
3120   return fold_build3 (COND_EXPR, result_type, ifexp, op1, op2);
3121 }
3122 \f
3123 /* Return a compound expression that performs two expressions and
3124    returns the value of the second of them.  */
3125
3126 tree
3127 build_compound_expr (tree expr1, tree expr2)
3128 {
3129   if (!TREE_SIDE_EFFECTS (expr1))
3130     {
3131       /* The left-hand operand of a comma expression is like an expression
3132          statement: with -Wextra or -Wunused, we should warn if it doesn't have
3133          any side-effects, unless it was explicitly cast to (void).  */
3134       if (warn_unused_value)
3135         {
3136           if (VOID_TYPE_P (TREE_TYPE (expr1))
3137               && TREE_CODE (expr1) == CONVERT_EXPR)
3138             ; /* (void) a, b */
3139           else if (VOID_TYPE_P (TREE_TYPE (expr1))
3140                    && TREE_CODE (expr1) == COMPOUND_EXPR
3141                    && TREE_CODE (TREE_OPERAND (expr1, 1)) == CONVERT_EXPR)
3142             ; /* (void) a, (void) b, c */
3143           else
3144             warning (0, "left-hand operand of comma expression has no effect");
3145         }
3146     }
3147
3148   /* With -Wunused, we should also warn if the left-hand operand does have
3149      side-effects, but computes a value which is not used.  For example, in
3150      `foo() + bar(), baz()' the result of the `+' operator is not used,
3151      so we should issue a warning.  */
3152   else if (warn_unused_value)
3153     warn_if_unused_value (expr1, input_location);
3154
3155   return build2 (COMPOUND_EXPR, TREE_TYPE (expr2), expr1, expr2);
3156 }
3157
3158 /* Build an expression representing a cast to type TYPE of expression EXPR.  */
3159
3160 tree
3161 build_c_cast (tree type, tree expr)
3162 {
3163   tree value = expr;
3164
3165   if (type == error_mark_node || expr == error_mark_node)
3166     return error_mark_node;
3167
3168   /* The ObjC front-end uses TYPE_MAIN_VARIANT to tie together types differing
3169      only in <protocol> qualifications.  But when constructing cast expressions,
3170      the protocols do matter and must be kept around.  */
3171   if (objc_is_object_ptr (type) && objc_is_object_ptr (TREE_TYPE (expr)))
3172     return build1 (NOP_EXPR, type, expr);
3173
3174   type = TYPE_MAIN_VARIANT (type);
3175
3176   if (TREE_CODE (type) == ARRAY_TYPE)
3177     {
3178       error ("cast specifies array type");
3179       return error_mark_node;
3180     }
3181
3182   if (TREE_CODE (type) == FUNCTION_TYPE)
3183     {
3184       error ("cast specifies function type");
3185       return error_mark_node;
3186     }
3187
3188   if (type == TYPE_MAIN_VARIANT (TREE_TYPE (value)))
3189     {
3190       if (pedantic)
3191         {
3192           if (TREE_CODE (type) == RECORD_TYPE
3193               || TREE_CODE (type) == UNION_TYPE)
3194             pedwarn ("ISO C forbids casting nonscalar to the same type");
3195         }
3196     }
3197   else if (TREE_CODE (type) == UNION_TYPE)
3198     {
3199       tree field;
3200
3201       for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
3202         if (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (field)),
3203                        TYPE_MAIN_VARIANT (TREE_TYPE (value))))
3204           break;
3205
3206       if (field)
3207         {
3208           tree t;
3209
3210           if (pedantic)
3211             pedwarn ("ISO C forbids casts to union type");
3212           t = digest_init (type,
3213                            build_constructor (type,
3214                                               build_tree_list (field, value)),
3215                            true, 0);
3216           TREE_CONSTANT (t) = TREE_CONSTANT (value);
3217           TREE_INVARIANT (t) = TREE_INVARIANT (value);
3218           return t;
3219         }
3220       error ("cast to union type from type not present in union");
3221       return error_mark_node;
3222     }
3223   else
3224     {
3225       tree otype, ovalue;
3226
3227       if (type == void_type_node)
3228         return build1 (CONVERT_EXPR, type, value);
3229
3230       otype = TREE_TYPE (value);
3231
3232       /* Optionally warn about potentially worrisome casts.  */
3233
3234       if (warn_cast_qual
3235           && TREE_CODE (type) == POINTER_TYPE
3236           && TREE_CODE (otype) == POINTER_TYPE)
3237         {
3238           tree in_type = type;
3239           tree in_otype = otype;
3240           int added = 0;
3241           int discarded = 0;
3242
3243           /* Check that the qualifiers on IN_TYPE are a superset of
3244              the qualifiers of IN_OTYPE.  The outermost level of
3245              POINTER_TYPE nodes is uninteresting and we stop as soon
3246              as we hit a non-POINTER_TYPE node on either type.  */
3247           do
3248             {
3249               in_otype = TREE_TYPE (in_otype);
3250               in_type = TREE_TYPE (in_type);
3251
3252               /* GNU C allows cv-qualified function types.  'const'
3253                  means the function is very pure, 'volatile' means it
3254                  can't return.  We need to warn when such qualifiers
3255                  are added, not when they're taken away.  */
3256               if (TREE_CODE (in_otype) == FUNCTION_TYPE
3257                   && TREE_CODE (in_type) == FUNCTION_TYPE)
3258                 added |= (TYPE_QUALS (in_type) & ~TYPE_QUALS (in_otype));
3259               else
3260                 discarded |= (TYPE_QUALS (in_otype) & ~TYPE_QUALS (in_type));
3261             }
3262           while (TREE_CODE (in_type) == POINTER_TYPE
3263                  && TREE_CODE (in_otype) == POINTER_TYPE);
3264
3265           if (added)
3266             warning (0, "cast adds new qualifiers to function type");
3267
3268           if (discarded)
3269             /* There are qualifiers present in IN_OTYPE that are not
3270                present in IN_TYPE.  */
3271             warning (0, "cast discards qualifiers from pointer target type");
3272         }
3273
3274       /* Warn about possible alignment problems.  */
3275       if (STRICT_ALIGNMENT
3276           && TREE_CODE (type) == POINTER_TYPE
3277           && TREE_CODE (otype) == POINTER_TYPE
3278           && TREE_CODE (TREE_TYPE (otype)) != VOID_TYPE
3279           && TREE_CODE (TREE_TYPE (otype)) != FUNCTION_TYPE
3280           /* Don't warn about opaque types, where the actual alignment
3281              restriction is unknown.  */
3282           && !((TREE_CODE (TREE_TYPE (otype)) == UNION_TYPE
3283                 || TREE_CODE (TREE_TYPE (otype)) == RECORD_TYPE)
3284                && TYPE_MODE (TREE_TYPE (otype)) == VOIDmode)
3285           && TYPE_ALIGN (TREE_TYPE (type)) > TYPE_ALIGN (TREE_TYPE (otype)))
3286         warning (OPT_Wcast_align,
3287                  "cast increases required alignment of target type");
3288
3289       if (TREE_CODE (type) == INTEGER_TYPE
3290           && TREE_CODE (otype) == POINTER_TYPE
3291           && TYPE_PRECISION (type) != TYPE_PRECISION (otype)
3292           && !TREE_CONSTANT (value))
3293         warning (OPT_Wpointer_to_int_cast,
3294                  "cast from pointer to integer of different size");
3295
3296       if (TREE_CODE (value) == CALL_EXPR
3297           && TREE_CODE (type) != TREE_CODE (otype))
3298         warning (OPT_Wbad_function_cast, "cast from function call of type %qT "
3299                  "to non-matching type %qT", otype, type);
3300
3301       if (TREE_CODE (type) == POINTER_TYPE
3302           && TREE_CODE (otype) == INTEGER_TYPE
3303           && TYPE_PRECISION (type) != TYPE_PRECISION (otype)
3304           /* Don't warn about converting any constant.  */
3305           && !TREE_CONSTANT (value))
3306         warning (OPT_Wint_to_pointer_cast, "cast to pointer from integer "
3307                  "of different size");
3308
3309       if (flag_strict_aliasing && warn_strict_aliasing
3310           && TREE_CODE (type) == POINTER_TYPE
3311           && TREE_CODE (otype) == POINTER_TYPE
3312           && TREE_CODE (expr) == ADDR_EXPR
3313           && (DECL_P (TREE_OPERAND (expr, 0))
3314               || TREE_CODE (TREE_OPERAND (expr, 0)) == COMPONENT_REF)
3315           && !VOID_TYPE_P (TREE_TYPE (type)))
3316         {
3317           /* Casting the address of an object to non void pointer. Warn
3318              if the cast breaks type based aliasing.  */
3319           if (!COMPLETE_TYPE_P (TREE_TYPE (type)))
3320             warning (OPT_Wstrict_aliasing, "type-punning to incomplete type "
3321                      "might break strict-aliasing rules");
3322           else
3323             {
3324               HOST_WIDE_INT set1 = get_alias_set (TREE_TYPE (TREE_OPERAND (expr, 0)));
3325               HOST_WIDE_INT set2 = get_alias_set (TREE_TYPE (type));
3326
3327               if (!alias_sets_conflict_p (set1, set2))
3328                 warning (OPT_Wstrict_aliasing, "dereferencing type-punned "
3329                          "pointer will break strict-aliasing rules");
3330               else if (warn_strict_aliasing > 1
3331                        && !alias_sets_might_conflict_p (set1, set2))
3332                 warning (OPT_Wstrict_aliasing, "dereferencing type-punned "
3333                          "pointer might break strict-aliasing rules");
3334             }
3335         }
3336
3337       /* If pedantic, warn for conversions between function and object
3338          pointer types, except for converting a null pointer constant
3339          to function pointer type.  */
3340       if (pedantic
3341           && TREE_CODE (type) == POINTER_TYPE
3342           && TREE_CODE (otype) == POINTER_TYPE
3343           && TREE_CODE (TREE_TYPE (otype)) == FUNCTION_TYPE
3344           && TREE_CODE (TREE_TYPE (type)) != FUNCTION_TYPE)
3345         pedwarn ("ISO C forbids conversion of function pointer to object pointer type");
3346
3347       if (pedantic
3348           && TREE_CODE (type) == POINTER_TYPE
3349           && TREE_CODE (otype) == POINTER_TYPE
3350           && TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE
3351           && TREE_CODE (TREE_TYPE (otype)) != FUNCTION_TYPE
3352           && !(integer_zerop (value) && TREE_TYPE (otype) == void_type_node
3353                && TREE_CODE (expr) != NOP_EXPR))
3354         pedwarn ("ISO C forbids conversion of object pointer to function pointer type");
3355
3356       ovalue = value;
3357       value = convert (type, value);
3358
3359       /* Ignore any integer overflow caused by the cast.  */
3360       if (TREE_CODE (value) == INTEGER_CST)
3361         {
3362           /* If OVALUE had overflow set, then so will VALUE, so it
3363              is safe to overwrite.  */
3364           if (CONSTANT_CLASS_P (ovalue))
3365             {
3366               TREE_OVERFLOW (value) = TREE_OVERFLOW (ovalue);
3367               /* Similarly, constant_overflow cannot have become cleared.  */
3368               TREE_CONSTANT_OVERFLOW (value) = TREE_CONSTANT_OVERFLOW (ovalue);
3369             }
3370           else
3371             TREE_OVERFLOW (value) = 0;
3372         }
3373     }
3374
3375   /* Don't let a cast be an lvalue.  */
3376   if (value == expr)
3377     value = non_lvalue (value);
3378
3379   return value;
3380 }
3381
3382 /* Interpret a cast of expression EXPR to type TYPE.  */
3383 tree
3384 c_cast_expr (struct c_type_name *type_name, tree expr)
3385 {
3386   tree type;
3387   int saved_wsp = warn_strict_prototypes;
3388
3389   /* This avoids warnings about unprototyped casts on
3390      integers.  E.g. "#define SIG_DFL (void(*)())0".  */
3391   if (TREE_CODE (expr) == INTEGER_CST)
3392     warn_strict_prototypes = 0;
3393   type = groktypename (type_name);
3394   warn_strict_prototypes = saved_wsp;
3395
3396   return build_c_cast (type, expr);
3397 }
3398
3399 \f
3400 /* Build an assignment expression of lvalue LHS from value RHS.
3401    MODIFYCODE is the code for a binary operator that we use
3402    to combine the old value of LHS with RHS to get the new value.
3403    Or else MODIFYCODE is NOP_EXPR meaning do a simple assignment.  */
3404
3405 tree
3406 build_modify_expr (tree lhs, enum tree_code modifycode, tree rhs)
3407 {
3408   tree result;
3409   tree newrhs;
3410   tree lhstype = TREE_TYPE (lhs);
3411   tree olhstype = lhstype;
3412
3413   /* Types that aren't fully specified cannot be used in assignments.  */
3414   lhs = require_complete_type (lhs);
3415
3416   /* Avoid duplicate error messages from operands that had errors.  */
3417   if (TREE_CODE (lhs) == ERROR_MARK || TREE_CODE (rhs) == ERROR_MARK)
3418     return error_mark_node;
3419
3420   STRIP_TYPE_NOPS (rhs);
3421
3422   newrhs = rhs;
3423
3424   /* If a binary op has been requested, combine the old LHS value with the RHS
3425      producing the value we should actually store into the LHS.  */
3426
3427   if (modifycode != NOP_EXPR)
3428     {
3429       lhs = stabilize_reference (lhs);
3430       newrhs = build_binary_op (modifycode, lhs, rhs, 1);
3431     }
3432
3433   if (!lvalue_or_else (lhs, lv_assign))
3434     return error_mark_node;
3435
3436   /* Give an error for storing in something that is 'const'.  */
3437
3438   if (TREE_READONLY (lhs) || TYPE_READONLY (lhstype)
3439       || ((TREE_CODE (lhstype) == RECORD_TYPE
3440            || TREE_CODE (lhstype) == UNION_TYPE)
3441           && C_TYPE_FIELDS_READONLY (lhstype)))
3442     readonly_error (lhs, lv_assign);
3443
3444   /* If storing into a structure or union member,
3445      it has probably been given type `int'.
3446      Compute the type that would go with
3447      the actual amount of storage the member occupies.  */
3448
3449   if (TREE_CODE (lhs) == COMPONENT_REF
3450       && (TREE_CODE (lhstype) == INTEGER_TYPE
3451           || TREE_CODE (lhstype) == BOOLEAN_TYPE
3452           || TREE_CODE (lhstype) == REAL_TYPE
3453           || TREE_CODE (lhstype) == ENUMERAL_TYPE))
3454     lhstype = TREE_TYPE (get_unwidened (lhs, 0));
3455
3456   /* If storing in a field that is in actuality a short or narrower than one,
3457      we must store in the field in its actual type.  */
3458
3459   if (lhstype != TREE_TYPE (lhs))
3460     {
3461       lhs = copy_node (lhs);
3462       TREE_TYPE (lhs) = lhstype;
3463     }
3464
3465   /* Convert new value to destination type.  */
3466
3467   newrhs = convert_for_assignment (lhstype, newrhs, ic_assign,
3468                                    NULL_TREE, NULL_TREE, 0);
3469   if (TREE_CODE (newrhs) == ERROR_MARK)
3470     return error_mark_node;
3471
3472   /* Emit ObjC write barrier, if necessary.  */
3473   if (c_dialect_objc () && flag_objc_gc)
3474     {
3475       result = objc_generate_write_barrier (lhs, modifycode, newrhs);
3476       if (result)
3477         return result;
3478     }
3479
3480   /* Scan operands.  */
3481
3482   result = build2 (MODIFY_EXPR, lhstype, lhs, newrhs);
3483   TREE_SIDE_EFFECTS (result) = 1;
3484
3485   /* If we got the LHS in a different type for storing in,
3486      convert the result back to the nominal type of LHS
3487      so that the value we return always has the same type
3488      as the LHS argument.  */
3489
3490   if (olhstype == TREE_TYPE (result))
3491     return result;
3492   return convert_for_assignment (olhstype, result, ic_assign,
3493                                  NULL_TREE, NULL_TREE, 0);
3494 }
3495 \f
3496 /* Convert value RHS to type TYPE as preparation for an assignment
3497    to an lvalue of type TYPE.
3498    The real work of conversion is done by `convert'.
3499    The purpose of this function is to generate error messages
3500    for assignments that are not allowed in C.
3501    ERRTYPE says whether it is argument passing, assignment,
3502    initialization or return.
3503
3504    FUNCTION is a tree for the function being called.
3505    PARMNUM is the number of the argument, for printing in error messages.  */
3506
3507 static tree
3508 convert_for_assignment (tree type, tree rhs, enum impl_conv errtype,
3509                         tree fundecl, tree function, int parmnum)
3510 {
3511   enum tree_code codel = TREE_CODE (type);
3512   tree rhstype;
3513   enum tree_code coder;
3514   tree rname = NULL_TREE;
3515   bool objc_ok = false;
3516
3517   if (errtype == ic_argpass || errtype == ic_argpass_nonproto)
3518     {
3519       tree selector;
3520       /* Change pointer to function to the function itself for
3521          diagnostics.  */
3522       if (TREE_CODE (function) == ADDR_EXPR
3523           && TREE_CODE (TREE_OPERAND (function, 0)) == FUNCTION_DECL)
3524         function = TREE_OPERAND (function, 0);
3525
3526       /* Handle an ObjC selector specially for diagnostics.  */
3527       selector = objc_message_selector ();
3528       rname = function;
3529       if (selector && parmnum > 2)
3530         {
3531           rname = selector;
3532           parmnum -= 2;
3533         }
3534     }
3535
3536   /* This macro is used to emit diagnostics to ensure that all format
3537      strings are complete sentences, visible to gettext and checked at
3538      compile time.  */
3539 #define WARN_FOR_ASSIGNMENT(AR, AS, IN, RE)     \
3540   do {                                          \
3541     switch (errtype)                            \
3542       {                                         \
3543       case ic_argpass:                          \
3544         pedwarn (AR, parmnum, rname);           \
3545         break;                                  \
3546       case ic_argpass_nonproto:                 \
3547         warning (0, AR, parmnum, rname);                \
3548         break;                                  \
3549       case ic_assign:                           \
3550         pedwarn (AS);                           \
3551         break;                                  \
3552       case ic_init:                             \
3553         pedwarn (IN);                           \
3554         break;                                  \
3555       case ic_return:                           \
3556         pedwarn (RE);                           \
3557         break;                                  \
3558       default:                                  \
3559         gcc_unreachable ();                     \
3560       }                                         \
3561   } while (0)
3562
3563   STRIP_TYPE_NOPS (rhs);
3564
3565   if (optimize && TREE_CODE (rhs) == VAR_DECL
3566            && TREE_CODE (TREE_TYPE (rhs)) != ARRAY_TYPE)
3567     rhs = decl_constant_value_for_broken_optimization (rhs);
3568
3569   rhstype = TREE_TYPE (rhs);
3570   coder = TREE_CODE (rhstype);
3571
3572   if (coder == ERROR_MARK)
3573     return error_mark_node;
3574
3575   if (c_dialect_objc ())
3576     {
3577       int parmno;
3578
3579       switch (errtype)
3580         {
3581         case ic_return:
3582           parmno = 0;
3583           break;
3584
3585         case ic_assign:
3586           parmno = -1;
3587           break;
3588
3589         case ic_init:
3590           parmno = -2;
3591           break;
3592
3593         default:
3594           parmno = parmnum;
3595           break;
3596         }
3597
3598       objc_ok = objc_compare_types (type, rhstype, parmno, rname);
3599     }
3600
3601   if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (rhstype))
3602     {
3603       overflow_warning (rhs);
3604       return rhs;
3605     }
3606
3607   if (coder == VOID_TYPE)
3608     {
3609       /* Except for passing an argument to an unprototyped function,
3610          this is a constraint violation.  When passing an argument to
3611          an unprototyped function, it is compile-time undefined;
3612          making it a constraint in that case was rejected in
3613          DR#252.  */
3614       error ("void value not ignored as it ought to be");
3615       return error_mark_node;
3616     }
3617   /* A type converts to a reference to it.
3618      This code doesn't fully support references, it's just for the
3619      special case of va_start and va_copy.  */
3620   if (codel == REFERENCE_TYPE
3621       && comptypes (TREE_TYPE (type), TREE_TYPE (rhs)) == 1)
3622     {
3623       if (!lvalue_p (rhs))
3624         {
3625           error ("cannot pass rvalue to reference parameter");
3626           return error_mark_node;
3627         }
3628       if (!c_mark_addressable (rhs))
3629         return error_mark_node;
3630       rhs = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (rhs)), rhs);
3631
3632       /* We already know that these two types are compatible, but they
3633          may not be exactly identical.  In fact, `TREE_TYPE (type)' is
3634          likely to be __builtin_va_list and `TREE_TYPE (rhs)' is
3635          likely to be va_list, a typedef to __builtin_va_list, which
3636          is different enough that it will cause problems later.  */
3637       if (TREE_TYPE (TREE_TYPE (rhs)) != TREE_TYPE (type))
3638         rhs = build1 (NOP_EXPR, build_pointer_type (TREE_TYPE (type)), rhs);
3639
3640       rhs = build1 (NOP_EXPR, type, rhs);
3641       return rhs;
3642     }
3643   /* Some types can interconvert without explicit casts.  */
3644   else if (codel == VECTOR_TYPE && coder == VECTOR_TYPE
3645            && vector_types_convertible_p (type, TREE_TYPE (rhs)))
3646     return convert (type, rhs);
3647   /* Arithmetic types all interconvert, and enum is treated like int.  */
3648   else if ((codel == INTEGER_TYPE || codel == REAL_TYPE
3649             || codel == ENUMERAL_TYPE || codel == COMPLEX_TYPE
3650             || codel == BOOLEAN_TYPE)
3651            && (coder == INTEGER_TYPE || coder == REAL_TYPE
3652                || coder == ENUMERAL_TYPE || coder == COMPLEX_TYPE
3653                || coder == BOOLEAN_TYPE))
3654     return convert_and_check (type, rhs);
3655
3656   /* Conversion to a transparent union from its member types.
3657      This applies only to function arguments.  */
3658   else if (codel == UNION_TYPE && TYPE_TRANSPARENT_UNION (type)
3659            && (errtype == ic_argpass || errtype == ic_argpass_nonproto))
3660     {
3661       tree memb_types;
3662       tree marginal_memb_type = 0;
3663
3664       for (memb_types = TYPE_FIELDS (type); memb_types;
3665            memb_types = TREE_CHAIN (memb_types))
3666         {
3667           tree memb_type = TREE_TYPE (memb_types);
3668
3669           if (comptypes (TYPE_MAIN_VARIANT (memb_type),
3670                          TYPE_MAIN_VARIANT (rhstype)))
3671             break;
3672
3673           if (TREE_CODE (memb_type) != POINTER_TYPE)
3674             continue;
3675
3676           if (coder == POINTER_TYPE)
3677             {
3678               tree ttl = TREE_TYPE (memb_type);
3679               tree ttr = TREE_TYPE (rhstype);
3680
3681               /* Any non-function converts to a [const][volatile] void *
3682                  and vice versa; otherwise, targets must be the same.
3683                  Meanwhile, the lhs target must have all the qualifiers of
3684                  the rhs.  */
3685               if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
3686                   || comp_target_types (memb_type, rhstype))
3687                 {
3688                   /* If this type won't generate any warnings, use it.  */
3689                   if (TYPE_QUALS (ttl) == TYPE_QUALS (ttr)
3690                       || ((TREE_CODE (ttr) == FUNCTION_TYPE
3691                            && TREE_CODE (ttl) == FUNCTION_TYPE)
3692                           ? ((TYPE_QUALS (ttl) | TYPE_QUALS (ttr))
3693                              == TYPE_QUALS (ttr))
3694                           : ((TYPE_QUALS (ttl) | TYPE_QUALS (ttr))
3695                              == TYPE_QUALS (ttl))))
3696                     break;
3697
3698                   /* Keep looking for a better type, but remember this one.  */
3699                   if (!marginal_memb_type)
3700                     marginal_memb_type = memb_type;
3701                 }
3702             }
3703
3704           /* Can convert integer zero to any pointer type.  */
3705           if (integer_zerop (rhs)
3706               || (TREE_CODE (rhs) == NOP_EXPR
3707                   && integer_zerop (TREE_OPERAND (rhs, 0))))
3708             {
3709               rhs = null_pointer_node;
3710               break;
3711             }
3712         }
3713
3714       if (memb_types || marginal_memb_type)
3715         {
3716           if (!memb_types)
3717             {
3718               /* We have only a marginally acceptable member type;
3719                  it needs a warning.  */
3720               tree ttl = TREE_TYPE (marginal_memb_type);
3721               tree ttr = TREE_TYPE (rhstype);
3722
3723               /* Const and volatile mean something different for function
3724                  types, so the usual warnings are not appropriate.  */
3725               if (TREE_CODE (ttr) == FUNCTION_TYPE
3726                   && TREE_CODE (ttl) == FUNCTION_TYPE)
3727                 {
3728                   /* Because const and volatile on functions are
3729                      restrictions that say the function will not do
3730                      certain things, it is okay to use a const or volatile
3731                      function where an ordinary one is wanted, but not
3732                      vice-versa.  */
3733                   if (TYPE_QUALS (ttl) & ~TYPE_QUALS (ttr))
3734                     WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE "
3735                                             "makes qualified function "
3736                                             "pointer from unqualified"),
3737                                          G_("assignment makes qualified "
3738                                             "function pointer from "
3739                                             "unqualified"),
3740                                          G_("initialization makes qualified "
3741                                             "function pointer from "
3742                                             "unqualified"),
3743                                          G_("return makes qualified function "
3744                                             "pointer from unqualified"));
3745                 }
3746               else if (TYPE_QUALS (ttr) & ~TYPE_QUALS (ttl))
3747                 WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE discards "
3748                                         "qualifiers from pointer target type"),
3749                                      G_("assignment discards qualifiers "
3750                                         "from pointer target type"),
3751                                      G_("initialization discards qualifiers "
3752                                         "from pointer target type"),
3753                                      G_("return discards qualifiers from "
3754                                         "pointer target type"));
3755             }
3756
3757           if (pedantic && !DECL_IN_SYSTEM_HEADER (fundecl))
3758             pedwarn ("ISO C prohibits argument conversion to union type");
3759
3760           return build1 (NOP_EXPR, type, rhs);
3761         }
3762     }
3763
3764   /* Conversions among pointers */
3765   else if ((codel == POINTER_TYPE || codel == REFERENCE_TYPE)
3766            && (coder == codel))
3767     {
3768       tree ttl = TREE_TYPE (type);
3769       tree ttr = TREE_TYPE (rhstype);
3770       tree mvl = ttl;
3771       tree mvr = ttr;
3772       bool is_opaque_pointer;
3773       int target_cmp = 0;   /* Cache comp_target_types () result.  */
3774
3775       if (TREE_CODE (mvl) != ARRAY_TYPE)
3776         mvl = TYPE_MAIN_VARIANT (mvl);
3777       if (TREE_CODE (mvr) != ARRAY_TYPE)
3778         mvr = TYPE_MAIN_VARIANT (mvr);
3779       /* Opaque pointers are treated like void pointers.  */
3780       is_opaque_pointer = (targetm.vector_opaque_p (type)
3781                            || targetm.vector_opaque_p (rhstype))
3782         && TREE_CODE (ttl) == VECTOR_TYPE
3783         && TREE_CODE (ttr) == VECTOR_TYPE;
3784
3785       /* C++ does not allow the implicit conversion void* -> T*.  However,
3786          for the purpose of reducing the number of false positives, we
3787          tolerate the special case of
3788
3789                 int *p = NULL;
3790
3791          where NULL is typically defined in C to be '(void *) 0'.  */
3792       if (VOID_TYPE_P (ttr) && rhs != null_pointer_node && !VOID_TYPE_P (ttl))
3793         warning (OPT_Wc___compat, "request for implicit conversion from "
3794                  "%qT to %qT not permitted in C++", rhstype, type);
3795
3796       /* Any non-function converts to a [const][volatile] void *
3797          and vice versa; otherwise, targets must be the same.
3798          Meanwhile, the lhs target must have all the qualifiers of the rhs.  */
3799       if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
3800           || (target_cmp = comp_target_types (type, rhstype))
3801           || is_opaque_pointer
3802           || (c_common_unsigned_type (mvl)
3803               == c_common_unsigned_type (mvr)))
3804         {
3805           if (pedantic
3806               && ((VOID_TYPE_P (ttl) && TREE_CODE (ttr) == FUNCTION_TYPE)
3807                   ||
3808                   (VOID_TYPE_P (ttr)
3809                    /* Check TREE_CODE to catch cases like (void *) (char *) 0
3810                       which are not ANSI null ptr constants.  */
3811                    && (!integer_zerop (rhs) || TREE_CODE (rhs) == NOP_EXPR)
3812                    && TREE_CODE (ttl) == FUNCTION_TYPE)))
3813             WARN_FOR_ASSIGNMENT (G_("ISO C forbids passing argument %d of "
3814                                     "%qE between function pointer "
3815                                     "and %<void *%>"),
3816                                  G_("ISO C forbids assignment between "
3817                                     "function pointer and %<void *%>"),
3818                                  G_("ISO C forbids initialization between "
3819                                     "function pointer and %<void *%>"),
3820                                  G_("ISO C forbids return between function "
3821                                     "pointer and %<void *%>"));
3822           /* Const and volatile mean something different for function types,
3823              so the usual warnings are not appropriate.  */
3824           else if (TREE_CODE (ttr) != FUNCTION_TYPE
3825                    && TREE_CODE (ttl) != FUNCTION_TYPE)
3826             {
3827               if (TYPE_QUALS (ttr) & ~TYPE_QUALS (ttl))
3828                 {
3829                   /* Types differing only by the presence of the 'volatile'
3830                      qualifier are acceptable if the 'volatile' has been added
3831                      in by the Objective-C EH machinery.  */
3832                   if (!objc_type_quals_match (ttl, ttr))
3833                     WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE discards "
3834                                             "qualifiers from pointer target type"),
3835                                          G_("assignment discards qualifiers "
3836                                             "from pointer target type"),
3837                                          G_("initialization discards qualifiers "
3838                                             "from pointer target type"),
3839                                          G_("return discards qualifiers from "
3840                                             "pointer target type"));
3841                 }
3842               /* If this is not a case of ignoring a mismatch in signedness,
3843                  no warning.  */
3844               else if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
3845                        || target_cmp)
3846                 ;
3847               /* If there is a mismatch, do warn.  */
3848               else if (warn_pointer_sign)
3849                 WARN_FOR_ASSIGNMENT (G_("pointer targets in passing argument "
3850                                         "%d of %qE differ in signedness"),
3851                                      G_("pointer targets in assignment "
3852                                         "differ in signedness"),
3853                                      G_("pointer targets in initialization "
3854                                         "differ in signedness"),
3855                                      G_("pointer targets in return differ "
3856                                         "in signedness"));
3857             }
3858           else if (TREE_CODE (ttl) == FUNCTION_TYPE
3859                    && TREE_CODE (ttr) == FUNCTION_TYPE)
3860             {
3861               /* Because const and volatile on functions are restrictions
3862                  that say the function will not do certain things,
3863                  it is okay to use a const or volatile function
3864                  where an ordinary one is wanted, but not vice-versa.  */
3865               if (TYPE_QUALS (ttl) & ~TYPE_QUALS (ttr))
3866                 WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE makes "
3867                                         "qualified function pointer "
3868                                         "from unqualified"),
3869                                      G_("assignment makes qualified function "
3870                                         "pointer from unqualified"),
3871                                      G_("initialization makes qualified "
3872                                         "function pointer from unqualified"),
3873                                      G_("return makes qualified function "
3874                                         "pointer from unqualified"));
3875             }
3876         }
3877       else
3878         /* Avoid warning about the volatile ObjC EH puts on decls.  */
3879         if (!objc_ok)
3880           WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE from "
3881                                   "incompatible pointer type"),
3882                                G_("assignment from incompatible pointer type"),
3883                                G_("initialization from incompatible "
3884                                   "pointer type"),
3885                                G_("return from incompatible pointer type"));
3886
3887       return convert (type, rhs);
3888     }
3889   else if (codel == POINTER_TYPE && coder == ARRAY_TYPE)
3890     {
3891       /* ??? This should not be an error when inlining calls to
3892          unprototyped functions.  */
3893       error ("invalid use of non-lvalue array");
3894       return error_mark_node;
3895     }
3896   else if (codel == POINTER_TYPE && coder == INTEGER_TYPE)
3897     {
3898       /* An explicit constant 0 can convert to a pointer,
3899          or one that results from arithmetic, even including
3900          a cast to integer type.  */
3901       if (!(TREE_CODE (rhs) == INTEGER_CST && integer_zerop (rhs))
3902           &&
3903           !(TREE_CODE (rhs) == NOP_EXPR
3904             && TREE_CODE (TREE_TYPE (rhs)) == INTEGER_TYPE
3905             && TREE_CODE (TREE_OPERAND (rhs, 0)) == INTEGER_CST
3906             && integer_zerop (TREE_OPERAND (rhs, 0))))
3907         WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE makes "
3908                                 "pointer from integer without a cast"),
3909                              G_("assignment makes pointer from integer "
3910                                 "without a cast"),
3911                              G_("initialization makes pointer from "
3912                                 "integer without a cast"),
3913                              G_("return makes pointer from integer "
3914                                 "without a cast"));
3915
3916       return convert (type, rhs);
3917     }
3918   else if (codel == INTEGER_TYPE && coder == POINTER_TYPE)
3919     {
3920       WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE makes integer "
3921                               "from pointer without a cast"),
3922                            G_("assignment makes integer from pointer "
3923                               "without a cast"),
3924                            G_("initialization makes integer from pointer "
3925                               "without a cast"),
3926                            G_("return makes integer from pointer "
3927                               "without a cast"));
3928       return convert (type, rhs);
3929     }
3930   else if (codel == BOOLEAN_TYPE && coder == POINTER_TYPE)
3931     return convert (type, rhs);
3932
3933   switch (errtype)
3934     {
3935     case ic_argpass:
3936     case ic_argpass_nonproto:
3937       /* ??? This should not be an error when inlining calls to
3938          unprototyped functions.  */
3939       error ("incompatible type for argument %d of %qE", parmnum, rname);
3940       break;
3941     case ic_assign:
3942       error ("incompatible types in assignment");
3943       break;
3944     case ic_init:
3945       error ("incompatible types in initialization");
3946       break;
3947     case ic_return:
3948       error ("incompatible types in return");
3949       break;
3950     default:
3951       gcc_unreachable ();
3952     }
3953
3954   return error_mark_node;
3955 }
3956
3957 /* Convert VALUE for assignment into inlined parameter PARM.  ARGNUM
3958    is used for error and waring reporting and indicates which argument
3959    is being processed.  */
3960
3961 tree
3962 c_convert_parm_for_inlining (tree parm, tree value, tree fn, int argnum)
3963 {
3964   tree ret, type;
3965
3966   /* If FN was prototyped, the value has been converted already
3967      in convert_arguments.  */
3968   if (!value || TYPE_ARG_TYPES (TREE_TYPE (fn)))
3969     return value;
3970
3971   type = TREE_TYPE (parm);
3972   ret = convert_for_assignment (type, value,
3973                                 ic_argpass_nonproto, fn,
3974                                 fn, argnum);
3975   if (targetm.calls.promote_prototypes (TREE_TYPE (fn))
3976       && INTEGRAL_TYPE_P (type)
3977       && (TYPE_PRECISION (type) < TYPE_PRECISION (integer_type_node)))
3978     ret = default_conversion (ret);
3979   return ret;
3980 }
3981 \f
3982 /* If VALUE is a compound expr all of whose expressions are constant, then
3983    return its value.  Otherwise, return error_mark_node.
3984
3985    This is for handling COMPOUND_EXPRs as initializer elements
3986    which is allowed with a warning when -pedantic is specified.  */
3987
3988 static tree
3989 valid_compound_expr_initializer (tree value, tree endtype)
3990 {
3991   if (TREE_CODE (value) == COMPOUND_EXPR)
3992     {
3993       if (valid_compound_expr_initializer (TREE_OPERAND (value, 0), endtype)
3994           == error_mark_node)
3995         return error_mark_node;
3996       return valid_compound_expr_initializer (TREE_OPERAND (value, 1),
3997                                               endtype);
3998     }
3999   else if (!initializer_constant_valid_p (value, endtype))
4000     return error_mark_node;
4001   else
4002     return value;
4003 }
4004 \f
4005 /* Perform appropriate conversions on the initial value of a variable,
4006    store it in the declaration DECL,
4007    and print any error messages that are appropriate.
4008    If the init is invalid, store an ERROR_MARK.  */
4009
4010 void
4011 store_init_value (tree decl, tree init)
4012 {
4013   tree value, type;
4014
4015   /* If variable's type was invalidly declared, just ignore it.  */
4016
4017   type = TREE_TYPE (decl);
4018   if (TREE_CODE (type) == ERROR_MARK)
4019     return;
4020
4021   /* Digest the specified initializer into an expression.  */
4022
4023   value = digest_init (type, init, true, TREE_STATIC (decl));
4024
4025   /* Store the expression if valid; else report error.  */
4026
4027   if (!in_system_header
4028       && AGGREGATE_TYPE_P (TREE_TYPE (decl)) && !TREE_STATIC (decl))
4029     warning (OPT_Wtraditional, "traditional C rejects automatic "
4030              "aggregate initialization");
4031
4032   DECL_INITIAL (decl) = value;
4033
4034   /* ANSI wants warnings about out-of-range constant initializers.  */
4035   STRIP_TYPE_NOPS (value);
4036   constant_expression_warning (value);
4037
4038   /* Check if we need to set array size from compound literal size.  */
4039   if (TREE_CODE (type) == ARRAY_TYPE
4040       && TYPE_DOMAIN (type) == 0
4041       && value != error_mark_node)
4042     {
4043       tree inside_init = init;
4044
4045       STRIP_TYPE_NOPS (inside_init);
4046       inside_init = fold (inside_init);
4047
4048       if (TREE_CODE (inside_init) == COMPOUND_LITERAL_EXPR)
4049         {
4050           tree decl = COMPOUND_LITERAL_EXPR_DECL (inside_init);
4051
4052           if (TYPE_DOMAIN (TREE_TYPE (decl)))
4053             {
4054               /* For int foo[] = (int [3]){1}; we need to set array size
4055                  now since later on array initializer will be just the
4056                  brace enclosed list of the compound literal.  */
4057               TYPE_DOMAIN (type) = TYPE_DOMAIN (TREE_TYPE (decl));
4058               layout_type (type);
4059               layout_decl (decl, 0);
4060             }
4061         }
4062     }
4063 }
4064 \f
4065 /* Methods for storing and printing names for error messages.  */
4066
4067 /* Implement a spelling stack that allows components of a name to be pushed
4068    and popped.  Each element on the stack is this structure.  */
4069
4070 struct spelling
4071 {
4072   int kind;
4073   union
4074     {
4075       int i;
4076       const char *s;
4077     } u;
4078 };
4079
4080 #define SPELLING_STRING 1
4081 #define SPELLING_MEMBER 2
4082 #define SPELLING_BOUNDS 3
4083
4084 static struct spelling *spelling;       /* Next stack element (unused).  */
4085 static struct spelling *spelling_base;  /* Spelling stack base.  */
4086 static int spelling_size;               /* Size of the spelling stack.  */
4087
4088 /* Macros to save and restore the spelling stack around push_... functions.
4089    Alternative to SAVE_SPELLING_STACK.  */
4090
4091 #define SPELLING_DEPTH() (spelling - spelling_base)
4092 #define RESTORE_SPELLING_DEPTH(DEPTH) (spelling = spelling_base + (DEPTH))
4093
4094 /* Push an element on the spelling stack with type KIND and assign VALUE
4095    to MEMBER.  */
4096
4097 #define PUSH_SPELLING(KIND, VALUE, MEMBER)                              \
4098 {                                                                       \
4099   int depth = SPELLING_DEPTH ();                                        \
4100                                                                         \
4101   if (depth >= spelling_size)                                           \
4102     {                                                                   \
4103       spelling_size += 10;                                              \
4104       spelling_base = XRESIZEVEC (struct spelling, spelling_base,       \
4105                                   spelling_size);                       \
4106       RESTORE_SPELLING_DEPTH (depth);                                   \
4107     }                                                                   \
4108                                                                         \
4109   spelling->kind = (KIND);                                              \
4110   spelling->MEMBER = (VALUE);                                           \
4111   spelling++;                                                           \
4112 }
4113
4114 /* Push STRING on the stack.  Printed literally.  */
4115
4116 static void
4117 push_string (const char *string)
4118 {
4119   PUSH_SPELLING (SPELLING_STRING, string, u.s);
4120 }
4121
4122 /* Push a member name on the stack.  Printed as '.' STRING.  */
4123
4124 static void
4125 push_member_name (tree decl)
4126 {
4127   const char *const string
4128     = DECL_NAME (decl) ? IDENTIFIER_POINTER (DECL_NAME (decl)) : "<anonymous>";
4129   PUSH_SPELLING (SPELLING_MEMBER, string, u.s);
4130 }
4131
4132 /* Push an array bounds on the stack.  Printed as [BOUNDS].  */
4133
4134 static void
4135 push_array_bounds (int bounds)
4136 {
4137   PUSH_SPELLING (SPELLING_BOUNDS, bounds, u.i);
4138 }
4139
4140 /* Compute the maximum size in bytes of the printed spelling.  */
4141
4142 static int
4143 spelling_length (void)
4144 {
4145   int size = 0;
4146   struct spelling *p;
4147
4148   for (p = spelling_base; p < spelling; p++)
4149     {
4150       if (p->kind == SPELLING_BOUNDS)
4151         size += 25;
4152       else
4153         size += strlen (p->u.s) + 1;
4154     }
4155
4156   return size;
4157 }
4158
4159 /* Print the spelling to BUFFER and return it.  */
4160
4161 static char *
4162 print_spelling (char *buffer)
4163 {
4164   char *d = buffer;
4165   struct spelling *p;
4166
4167   for (p = spelling_base; p < spelling; p++)
4168     if (p->kind == SPELLING_BOUNDS)
4169       {
4170         sprintf (d, "[%d]", p->u.i);
4171         d += strlen (d);
4172       }
4173     else
4174       {
4175         const char *s;
4176         if (p->kind == SPELLING_MEMBER)
4177           *d++ = '.';
4178         for (s = p->u.s; (*d = *s++); d++)
4179           ;
4180       }
4181   *d++ = '\0';
4182   return buffer;
4183 }
4184
4185 /* Issue an error message for a bad initializer component.
4186    MSGID identifies the message.
4187    The component name is taken from the spelling stack.  */
4188
4189 void
4190 error_init (const char *msgid)
4191 {
4192   char *ofwhat;
4193
4194   error ("%s", _(msgid));
4195   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4196   if (*ofwhat)
4197     error ("(near initialization for %qs)", ofwhat);
4198 }
4199
4200 /* Issue a pedantic warning for a bad initializer component.
4201    MSGID identifies the message.
4202    The component name is taken from the spelling stack.  */
4203
4204 void
4205 pedwarn_init (const char *msgid)
4206 {
4207   char *ofwhat;
4208
4209   pedwarn ("%s", _(msgid));
4210   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4211   if (*ofwhat)
4212     pedwarn ("(near initialization for %qs)", ofwhat);
4213 }
4214
4215 /* Issue a warning for a bad initializer component.
4216    MSGID identifies the message.
4217    The component name is taken from the spelling stack.  */
4218
4219 static void
4220 warning_init (const char *msgid)
4221 {
4222   char *ofwhat;
4223
4224   warning (0, "%s", _(msgid));
4225   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4226   if (*ofwhat)
4227     warning (0, "(near initialization for %qs)", ofwhat);
4228 }
4229 \f
4230 /* If TYPE is an array type and EXPR is a parenthesized string
4231    constant, warn if pedantic that EXPR is being used to initialize an
4232    object of type TYPE.  */
4233
4234 void
4235 maybe_warn_string_init (tree type, struct c_expr expr)
4236 {
4237   if (pedantic
4238       && TREE_CODE (type) == ARRAY_TYPE
4239       && TREE_CODE (expr.value) == STRING_CST
4240       && expr.original_code != STRING_CST)
4241     pedwarn_init ("array initialized from parenthesized string constant");
4242 }
4243
4244 /* Digest the parser output INIT as an initializer for type TYPE.
4245    Return a C expression of type TYPE to represent the initial value.
4246
4247    If INIT is a string constant, STRICT_STRING is true if it is
4248    unparenthesized or we should not warn here for it being parenthesized.
4249    For other types of INIT, STRICT_STRING is not used.
4250
4251    REQUIRE_CONSTANT requests an error if non-constant initializers or
4252    elements are seen.  */
4253
4254 static tree
4255 digest_init (tree type, tree init, bool strict_string, int require_constant)
4256 {
4257   enum tree_code code = TREE_CODE (type);
4258   tree inside_init = init;
4259
4260   if (type == error_mark_node
4261       || init == error_mark_node
4262       || TREE_TYPE (init) == error_mark_node)
4263     return error_mark_node;
4264
4265   STRIP_TYPE_NOPS (inside_init);
4266
4267   inside_init = fold (inside_init);
4268
4269   /* Initialization of an array of chars from a string constant
4270      optionally enclosed in braces.  */
4271
4272   if (code == ARRAY_TYPE && inside_init
4273       && TREE_CODE (inside_init) == STRING_CST)
4274     {
4275       tree typ1 = TYPE_MAIN_VARIANT (TREE_TYPE (type));
4276       /* Note that an array could be both an array of character type
4277          and an array of wchar_t if wchar_t is signed char or unsigned
4278          char.  */
4279       bool char_array = (typ1 == char_type_node
4280                          || typ1 == signed_char_type_node
4281                          || typ1 == unsigned_char_type_node);
4282       bool wchar_array = !!comptypes (typ1, wchar_type_node);
4283       if (char_array || wchar_array)
4284         {
4285           struct c_expr expr;
4286           bool char_string;
4287           expr.value = inside_init;
4288           expr.original_code = (strict_string ? STRING_CST : ERROR_MARK);
4289           maybe_warn_string_init (type, expr);
4290
4291           char_string
4292             = (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (inside_init)))
4293                == char_type_node);
4294
4295           if (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4296                          TYPE_MAIN_VARIANT (type)))
4297             return inside_init;
4298
4299           if (!wchar_array && !char_string)
4300             {
4301               error_init ("char-array initialized from wide string");
4302               return error_mark_node;
4303             }
4304           if (char_string && !char_array)
4305             {
4306               error_init ("wchar_t-array initialized from non-wide string");
4307               return error_mark_node;
4308             }
4309
4310           TREE_TYPE (inside_init) = type;
4311           if (TYPE_DOMAIN (type) != 0
4312               && TYPE_SIZE (type) != 0
4313               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
4314               /* Subtract 1 (or sizeof (wchar_t))
4315                  because it's ok to ignore the terminating null char
4316                  that is counted in the length of the constant.  */
4317               && 0 > compare_tree_int (TYPE_SIZE_UNIT (type),
4318                                        TREE_STRING_LENGTH (inside_init)
4319                                        - ((TYPE_PRECISION (typ1)
4320                                            != TYPE_PRECISION (char_type_node))
4321                                           ? (TYPE_PRECISION (wchar_type_node)
4322                                              / BITS_PER_UNIT)
4323                                           : 1)))
4324             pedwarn_init ("initializer-string for array of chars is too long");
4325
4326           return inside_init;
4327         }
4328       else if (INTEGRAL_TYPE_P (typ1))
4329         {
4330           error_init ("array of inappropriate type initialized "
4331                       "from string constant");
4332           return error_mark_node;
4333         }
4334     }
4335
4336   /* Build a VECTOR_CST from a *constant* vector constructor.  If the
4337      vector constructor is not constant (e.g. {1,2,3,foo()}) then punt
4338      below and handle as a constructor.  */
4339   if (code == VECTOR_TYPE
4340       && TREE_CODE (TREE_TYPE (inside_init)) == VECTOR_TYPE
4341       && vector_types_convertible_p (TREE_TYPE (inside_init), type)
4342       && TREE_CONSTANT (inside_init))
4343     {
4344       if (TREE_CODE (inside_init) == VECTOR_CST
4345           && comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4346                         TYPE_MAIN_VARIANT (type)))
4347         return inside_init;
4348
4349       if (TREE_CODE (inside_init) == CONSTRUCTOR)
4350         {
4351           tree link;
4352
4353           /* Iterate through elements and check if all constructor
4354              elements are *_CSTs.  */
4355           for (link = CONSTRUCTOR_ELTS (inside_init);
4356                link;
4357                link = TREE_CHAIN (link))
4358             if (! CONSTANT_CLASS_P (TREE_VALUE (link)))
4359               break;
4360
4361           if (link == NULL)
4362             return build_vector (type, CONSTRUCTOR_ELTS (inside_init));
4363         }
4364     }
4365
4366   /* Any type can be initialized
4367      from an expression of the same type, optionally with braces.  */
4368
4369   if (inside_init && TREE_TYPE (inside_init) != 0
4370       && (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4371                      TYPE_MAIN_VARIANT (type))
4372           || (code == ARRAY_TYPE
4373               && comptypes (TREE_TYPE (inside_init), type))
4374           || (code == VECTOR_TYPE
4375               && comptypes (TREE_TYPE (inside_init), type))
4376           || (code == POINTER_TYPE
4377               && TREE_CODE (TREE_TYPE (inside_init)) == ARRAY_TYPE
4378               && comptypes (TREE_TYPE (TREE_TYPE (inside_init)),
4379                             TREE_TYPE (type)))))
4380     {
4381       if (code == POINTER_TYPE)
4382         {
4383           if (TREE_CODE (TREE_TYPE (inside_init)) == ARRAY_TYPE)
4384             {
4385               if (TREE_CODE (inside_init) == STRING_CST
4386                   || TREE_CODE (inside_init) == COMPOUND_LITERAL_EXPR)
4387                 inside_init = array_to_pointer_conversion (inside_init);
4388               else
4389                 {
4390                   error_init ("invalid use of non-lvalue array");
4391                   return error_mark_node;
4392                 }
4393             }
4394         }
4395
4396       if (code == VECTOR_TYPE)
4397         /* Although the types are compatible, we may require a
4398            conversion.  */
4399         inside_init = convert (type, inside_init);
4400
4401       if (require_constant && !flag_isoc99
4402           && TREE_CODE (inside_init) == COMPOUND_LITERAL_EXPR)
4403         {
4404           /* As an extension, allow initializing objects with static storage
4405              duration with compound literals (which are then treated just as
4406              the brace enclosed list they contain).  */
4407           tree decl = COMPOUND_LITERAL_EXPR_DECL (inside_init);
4408           inside_init = DECL_INITIAL (decl);
4409         }
4410
4411       if (code == ARRAY_TYPE && TREE_CODE (inside_init) != STRING_CST
4412           && TREE_CODE (inside_init) != CONSTRUCTOR)
4413         {
4414           error_init ("array initialized from non-constant array expression");
4415           return error_mark_node;
4416         }
4417
4418       if (optimize && TREE_CODE (inside_init) == VAR_DECL)
4419         inside_init = decl_constant_value_for_broken_optimization (inside_init);
4420
4421       /* Compound expressions can only occur here if -pedantic or
4422          -pedantic-errors is specified.  In the later case, we always want
4423          an error.  In the former case, we simply want a warning.  */
4424       if (require_constant && pedantic
4425           && TREE_CODE (inside_init) == COMPOUND_EXPR)
4426         {
4427           inside_init
4428             = valid_compound_expr_initializer (inside_init,
4429                                                TREE_TYPE (inside_init));
4430           if (inside_init == error_mark_node)
4431             error_init ("initializer element is not constant");
4432           else
4433             pedwarn_init ("initializer element is not constant");
4434           if (flag_pedantic_errors)
4435             inside_init = error_mark_node;
4436         }
4437       else if (require_constant
4438                && !initializer_constant_valid_p (inside_init,
4439                                                  TREE_TYPE (inside_init)))
4440         {
4441           error_init ("initializer element is not constant");
4442           inside_init = error_mark_node;
4443         }
4444
4445       return inside_init;
4446     }
4447
4448   /* Handle scalar types, including conversions.  */
4449
4450   if (code == INTEGER_TYPE || code == REAL_TYPE || code == POINTER_TYPE
4451       || code == ENUMERAL_TYPE || code == BOOLEAN_TYPE || code == COMPLEX_TYPE
4452       || code == VECTOR_TYPE)
4453     {
4454       if (TREE_CODE (TREE_TYPE (init)) == ARRAY_TYPE
4455           && (TREE_CODE (init) == STRING_CST
4456               || TREE_CODE (init) == COMPOUND_LITERAL_EXPR))
4457         init = array_to_pointer_conversion (init);
4458       inside_init
4459         = convert_for_assignment (type, init, ic_init,
4460                                   NULL_TREE, NULL_TREE, 0);
4461
4462       /* Check to see if we have already given an error message.  */
4463       if (inside_init == error_mark_node)
4464         ;
4465       else if (require_constant && !TREE_CONSTANT (inside_init))
4466         {
4467           error_init ("initializer element is not constant");
4468           inside_init = error_mark_node;
4469         }
4470       else if (require_constant
4471                && !initializer_constant_valid_p (inside_init,
4472                                                  TREE_TYPE (inside_init)))
4473         {
4474           error_init ("initializer element is not computable at load time");
4475           inside_init = error_mark_node;
4476         }
4477
4478       return inside_init;
4479     }
4480
4481   /* Come here only for records and arrays.  */
4482
4483   if (COMPLETE_TYPE_P (type) && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
4484     {
4485       error_init ("variable-sized object may not be initialized");
4486       return error_mark_node;
4487     }
4488
4489   error_init ("invalid initializer");
4490   return error_mark_node;
4491 }
4492 \f
4493 /* Handle initializers that use braces.  */
4494
4495 /* Type of object we are accumulating a constructor for.
4496    This type is always a RECORD_TYPE, UNION_TYPE or ARRAY_TYPE.  */
4497 static tree constructor_type;
4498
4499 /* For a RECORD_TYPE or UNION_TYPE, this is the chain of fields
4500    left to fill.  */
4501 static tree constructor_fields;
4502
4503 /* For an ARRAY_TYPE, this is the specified index
4504    at which to store the next element we get.  */
4505 static tree constructor_index;
4506
4507 /* For an ARRAY_TYPE, this is the maximum index.  */
4508 static tree constructor_max_index;
4509
4510 /* For a RECORD_TYPE, this is the first field not yet written out.  */
4511 static tree constructor_unfilled_fields;
4512
4513 /* For an ARRAY_TYPE, this is the index of the first element
4514    not yet written out.  */
4515 static tree constructor_unfilled_index;
4516
4517 /* In a RECORD_TYPE, the byte index of the next consecutive field.
4518    This is so we can generate gaps between fields, when appropriate.  */
4519 static tree constructor_bit_index;
4520
4521 /* If we are saving up the elements rather than allocating them,
4522    this is the list of elements so far (in reverse order,
4523    most recent first).  */
4524 static tree constructor_elements;
4525
4526 /* 1 if constructor should be incrementally stored into a constructor chain,
4527    0 if all the elements should be kept in AVL tree.  */
4528 static int constructor_incremental;
4529
4530 /* 1 if so far this constructor's elements are all compile-time constants.  */
4531 static int constructor_constant;
4532
4533 /* 1 if so far this constructor's elements are all valid address constants.  */
4534 static int constructor_simple;
4535
4536 /* 1 if this constructor is erroneous so far.  */
4537 static int constructor_erroneous;
4538
4539 /* Structure for managing pending initializer elements, organized as an
4540    AVL tree.  */
4541
4542 struct init_node
4543 {
4544   struct init_node *left, *right;
4545   struct init_node *parent;
4546   int balance;
4547   tree purpose;
4548   tree value;
4549 };
4550
4551 /* Tree of pending elements at this constructor level.
4552    These are elements encountered out of order
4553    which belong at places we haven't reached yet in actually
4554    writing the output.
4555    Will never hold tree nodes across GC runs.  */
4556 static struct init_node *constructor_pending_elts;
4557
4558 /* The SPELLING_DEPTH of this constructor.  */
4559 static int constructor_depth;
4560
4561 /* DECL node for which an initializer is being read.
4562    0 means we are reading a constructor expression
4563    such as (struct foo) {...}.  */
4564 static tree constructor_decl;
4565
4566 /* Nonzero if this is an initializer for a top-level decl.  */
4567 static int constructor_top_level;
4568
4569 /* Nonzero if there were any member designators in this initializer.  */
4570 static int constructor_designated;
4571
4572 /* Nesting depth of designator list.  */
4573 static int designator_depth;
4574
4575 /* Nonzero if there were diagnosed errors in this designator list.  */
4576 static int designator_errorneous;
4577
4578 \f
4579 /* This stack has a level for each implicit or explicit level of
4580    structuring in the initializer, including the outermost one.  It
4581    saves the values of most of the variables above.  */
4582
4583 struct constructor_range_stack;
4584
4585 struct constructor_stack
4586 {
4587   struct constructor_stack *next;
4588   tree type;
4589   tree fields;
4590   tree index;
4591   tree max_index;
4592   tree unfilled_index;
4593   tree unfilled_fields;
4594   tree bit_index;
4595   tree elements;
4596   struct init_node *pending_elts;
4597   int offset;
4598   int depth;
4599   /* If value nonzero, this value should replace the entire
4600      constructor at this level.  */
4601   struct c_expr replacement_value;
4602   struct constructor_range_stack *range_stack;
4603   char constant;
4604   char simple;
4605   char implicit;
4606   char erroneous;
4607   char outer;
4608   char incremental;
4609   char designated;
4610 };
4611
4612 static struct constructor_stack *constructor_stack;
4613
4614 /* This stack represents designators from some range designator up to
4615    the last designator in the list.  */
4616
4617 struct constructor_range_stack
4618 {
4619   struct constructor_range_stack *next, *prev;
4620   struct constructor_stack *stack;
4621   tree range_start;
4622   tree index;
4623   tree range_end;
4624   tree fields;
4625 };
4626
4627 static struct constructor_range_stack *constructor_range_stack;
4628
4629 /* This stack records separate initializers that are nested.
4630    Nested initializers can't happen in ANSI C, but GNU C allows them
4631    in cases like { ... (struct foo) { ... } ... }.  */
4632
4633 struct initializer_stack
4634 {
4635   struct initializer_stack *next;
4636   tree decl;
4637   struct constructor_stack *constructor_stack;
4638   struct constructor_range_stack *constructor_range_stack;
4639   tree elements;
4640   struct spelling *spelling;
4641   struct spelling *spelling_base;
4642   int spelling_size;
4643   char top_level;
4644   char require_constant_value;
4645   char require_constant_elements;
4646 };
4647
4648 static struct initializer_stack *initializer_stack;
4649 \f
4650 /* Prepare to parse and output the initializer for variable DECL.  */
4651
4652 void
4653 start_init (tree decl, tree asmspec_tree ATTRIBUTE_UNUSED, int top_level)
4654 {
4655   const char *locus;
4656   struct initializer_stack *p = xmalloc (sizeof (struct initializer_stack));
4657
4658   p->decl = constructor_decl;
4659   p->require_constant_value = require_constant_value;
4660   p->require_constant_elements = require_constant_elements;
4661   p->constructor_stack = constructor_stack;
4662   p->constructor_range_stack = constructor_range_stack;
4663   p->elements = constructor_elements;
4664   p->spelling = spelling;
4665   p->spelling_base = spelling_base;
4666   p->spelling_size = spelling_size;
4667   p->top_level = constructor_top_level;
4668   p->next = initializer_stack;
4669   initializer_stack = p;
4670
4671   constructor_decl = decl;
4672   constructor_designated = 0;
4673   constructor_top_level = top_level;
4674
4675   if (decl != 0 && decl != error_mark_node)
4676     {
4677       require_constant_value = TREE_STATIC (decl);
4678       require_constant_elements
4679         = ((TREE_STATIC (decl) || (pedantic && !flag_isoc99))
4680            /* For a scalar, you can always use any value to initialize,
4681               even within braces.  */
4682            && (TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE
4683                || TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
4684                || TREE_CODE (TREE_TYPE (decl)) == UNION_TYPE
4685                || TREE_CODE (TREE_TYPE (decl)) == QUAL_UNION_TYPE));
4686       locus = IDENTIFIER_POINTER (DECL_NAME (decl));
4687     }
4688   else
4689     {
4690       require_constant_value = 0;
4691       require_constant_elements = 0;
4692       locus = "(anonymous)";
4693     }
4694
4695   constructor_stack = 0;
4696   constructor_range_stack = 0;
4697
4698   missing_braces_mentioned = 0;
4699
4700   spelling_base = 0;
4701   spelling_size = 0;
4702   RESTORE_SPELLING_DEPTH (0);
4703
4704   if (locus)
4705     push_string (locus);
4706 }
4707
4708 void
4709 finish_init (void)
4710 {
4711   struct initializer_stack *p = initializer_stack;
4712
4713   /* Free the whole constructor stack of this initializer.  */
4714   while (constructor_stack)
4715     {
4716       struct constructor_stack *q = constructor_stack;
4717       constructor_stack = q->next;
4718       free (q);
4719     }
4720
4721   gcc_assert (!constructor_range_stack);
4722
4723   /* Pop back to the data of the outer initializer (if any).  */
4724   free (spelling_base);
4725
4726   constructor_decl = p->decl;
4727   require_constant_value = p->require_constant_value;
4728   require_constant_elements = p->require_constant_elements;
4729   constructor_stack = p->constructor_stack;
4730   constructor_range_stack = p->constructor_range_stack;
4731   constructor_elements = p->elements;
4732   spelling = p->spelling;
4733   spelling_base = p->spelling_base;
4734   spelling_size = p->spelling_size;
4735   constructor_top_level = p->top_level;
4736   initializer_stack = p->next;
4737   free (p);
4738 }
4739 \f
4740 /* Call here when we see the initializer is surrounded by braces.
4741    This is instead of a call to push_init_level;
4742    it is matched by a call to pop_init_level.
4743
4744    TYPE is the type to initialize, for a constructor expression.
4745    For an initializer for a decl, TYPE is zero.  */
4746
4747 void
4748 really_start_incremental_init (tree type)
4749 {
4750   struct constructor_stack *p = XNEW (struct constructor_stack);
4751
4752   if (type == 0)
4753     type = TREE_TYPE (constructor_decl);
4754
4755   if (targetm.vector_opaque_p (type))
4756     error ("opaque vector types cannot be initialized");
4757
4758   p->type = constructor_type;
4759   p->fields = constructor_fields;
4760   p->index = constructor_index;
4761   p->max_index = constructor_max_index;
4762   p->unfilled_index = constructor_unfilled_index;
4763   p->unfilled_fields = constructor_unfilled_fields;
4764   p->bit_index = constructor_bit_index;
4765   p->elements = constructor_elements;
4766   p->constant = constructor_constant;
4767   p->simple = constructor_simple;
4768   p->erroneous = constructor_erroneous;
4769   p->pending_elts = constructor_pending_elts;
4770   p->depth = constructor_depth;
4771   p->replacement_value.value = 0;
4772   p->replacement_value.original_code = ERROR_MARK;
4773   p->implicit = 0;
4774   p->range_stack = 0;
4775   p->outer = 0;
4776   p->incremental = constructor_incremental;
4777   p->designated = constructor_designated;
4778   p->next = 0;
4779   constructor_stack = p;
4780
4781   constructor_constant = 1;
4782   constructor_simple = 1;
4783   constructor_depth = SPELLING_DEPTH ();
4784   constructor_elements = 0;
4785   constructor_pending_elts = 0;
4786   constructor_type = type;
4787   constructor_incremental = 1;
4788   constructor_designated = 0;
4789   designator_depth = 0;
4790   designator_errorneous = 0;
4791
4792   if (TREE_CODE (constructor_type) == RECORD_TYPE
4793       || TREE_CODE (constructor_type) == UNION_TYPE)
4794     {
4795       constructor_fields = TYPE_FIELDS (constructor_type);
4796       /* Skip any nameless bit fields at the beginning.  */
4797       while (constructor_fields != 0 && DECL_C_BIT_FIELD (constructor_fields)
4798              && DECL_NAME (constructor_fields) == 0)
4799         constructor_fields = TREE_CHAIN (constructor_fields);
4800
4801       constructor_unfilled_fields = constructor_fields;
4802       constructor_bit_index = bitsize_zero_node;
4803     }
4804   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
4805     {
4806       if (TYPE_DOMAIN (constructor_type))
4807         {
4808           constructor_max_index
4809             = TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type));
4810
4811           /* Detect non-empty initializations of zero-length arrays.  */
4812           if (constructor_max_index == NULL_TREE
4813               && TYPE_SIZE (constructor_type))
4814             constructor_max_index = build_int_cst (NULL_TREE, -1);
4815
4816           /* constructor_max_index needs to be an INTEGER_CST.  Attempts
4817              to initialize VLAs will cause a proper error; avoid tree
4818              checking errors as well by setting a safe value.  */
4819           if (constructor_max_index
4820               && TREE_CODE (constructor_max_index) != INTEGER_CST)
4821             constructor_max_index = build_int_cst (NULL_TREE, -1);
4822
4823           constructor_index
4824             = convert (bitsizetype,
4825                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
4826         }
4827       else
4828         {
4829           constructor_index = bitsize_zero_node;
4830           constructor_max_index = NULL_TREE;
4831         }
4832
4833       constructor_unfilled_index = constructor_index;
4834     }
4835   else if (TREE_CODE (constructor_type) == VECTOR_TYPE)
4836     {
4837       /* Vectors are like simple fixed-size arrays.  */
4838       constructor_max_index =
4839         build_int_cst (NULL_TREE, TYPE_VECTOR_SUBPARTS (constructor_type) - 1);
4840       constructor_index = convert (bitsizetype, bitsize_zero_node);
4841       constructor_unfilled_index = constructor_index;
4842     }
4843   else
4844     {
4845       /* Handle the case of int x = {5}; */
4846       constructor_fields = constructor_type;
4847       constructor_unfilled_fields = constructor_type;
4848     }
4849 }
4850 \f
4851 /* Push down into a subobject, for initialization.
4852    If this is for an explicit set of braces, IMPLICIT is 0.
4853    If it is because the next element belongs at a lower level,
4854    IMPLICIT is 1 (or 2 if the push is because of designator list).  */
4855
4856 void
4857 push_init_level (int implicit)
4858 {
4859   struct constructor_stack *p;
4860   tree value = NULL_TREE;
4861
4862   /* If we've exhausted any levels that didn't have braces,
4863      pop them now.  If implicit == 1, this will have been done in
4864      process_init_element; do not repeat it here because in the case
4865      of excess initializers for an empty aggregate this leads to an
4866      infinite cycle of popping a level and immediately recreating
4867      it.  */
4868   if (implicit != 1)
4869     {
4870       while (constructor_stack->implicit)
4871         {
4872           if ((TREE_CODE (constructor_type) == RECORD_TYPE
4873                || TREE_CODE (constructor_type) == UNION_TYPE)
4874               && constructor_fields == 0)
4875             process_init_element (pop_init_level (1));
4876           else if (TREE_CODE (constructor_type) == ARRAY_TYPE
4877                    && constructor_max_index
4878                    && tree_int_cst_lt (constructor_max_index,
4879                                        constructor_index))
4880             process_init_element (pop_init_level (1));
4881           else
4882             break;
4883         }
4884     }
4885
4886   /* Unless this is an explicit brace, we need to preserve previous
4887      content if any.  */
4888   if (implicit)
4889     {
4890       if ((TREE_CODE (constructor_type) == RECORD_TYPE
4891            || TREE_CODE (constructor_type) == UNION_TYPE)
4892           && constructor_fields)
4893         value = find_init_member (constructor_fields);
4894       else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
4895         value = find_init_member (constructor_index);
4896     }
4897
4898   p = XNEW (struct constructor_stack);
4899   p->type = constructor_type;
4900   p->fields = constructor_fields;
4901   p->index = constructor_index;
4902   p->max_index = constructor_max_index;
4903   p->unfilled_index = constructor_unfilled_index;
4904   p->unfilled_fields = constructor_unfilled_fields;
4905   p->bit_index = constructor_bit_index;
4906   p->elements = constructor_elements;
4907   p->constant = constructor_constant;
4908   p->simple = constructor_simple;
4909   p->erroneous = constructor_erroneous;
4910   p->pending_elts = constructor_pending_elts;
4911   p->depth = constructor_depth;
4912   p->replacement_value.value = 0;
4913   p->replacement_value.original_code = ERROR_MARK;
4914   p->implicit = implicit;
4915   p->outer = 0;
4916   p->incremental = constructor_incremental;
4917   p->designated = constructor_designated;
4918   p->next = constructor_stack;
4919   p->range_stack = 0;
4920   constructor_stack = p;
4921
4922   constructor_constant = 1;
4923   constructor_simple = 1;
4924   constructor_depth = SPELLING_DEPTH ();
4925   constructor_elements = 0;
4926   constructor_incremental = 1;
4927   constructor_designated = 0;
4928   constructor_pending_elts = 0;
4929   if (!implicit)
4930     {
4931       p->range_stack = constructor_range_stack;
4932       constructor_range_stack = 0;
4933       designator_depth = 0;
4934       designator_errorneous = 0;
4935     }
4936
4937   /* Don't die if an entire brace-pair level is superfluous
4938      in the containing level.  */
4939   if (constructor_type == 0)
4940     ;
4941   else if (TREE_CODE (constructor_type) == RECORD_TYPE
4942            || TREE_CODE (constructor_type) == UNION_TYPE)
4943     {
4944       /* Don't die if there are extra init elts at the end.  */
4945       if (constructor_fields == 0)
4946         constructor_type = 0;
4947       else
4948         {
4949           constructor_type = TREE_TYPE (constructor_fields);
4950           push_member_name (constructor_fields);
4951           constructor_depth++;
4952         }
4953     }
4954   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
4955     {
4956       constructor_type = TREE_TYPE (constructor_type);
4957       push_array_bounds (tree_low_cst (constructor_index, 0));
4958       constructor_depth++;
4959     }
4960
4961   if (constructor_type == 0)
4962     {
4963       error_init ("extra brace group at end of initializer");
4964       constructor_fields = 0;
4965       constructor_unfilled_fields = 0;
4966       return;
4967     }
4968
4969   if (value && TREE_CODE (value) == CONSTRUCTOR)
4970     {
4971       constructor_constant = TREE_CONSTANT (value);
4972       constructor_simple = TREE_STATIC (value);
4973       constructor_elements = CONSTRUCTOR_ELTS (value);
4974       if (constructor_elements
4975           && (TREE_CODE (constructor_type) == RECORD_TYPE
4976               || TREE_CODE (constructor_type) == ARRAY_TYPE))
4977         set_nonincremental_init ();
4978     }
4979
4980   if (implicit == 1 && warn_missing_braces && !missing_braces_mentioned)
4981     {
4982       missing_braces_mentioned = 1;
4983       warning_init ("missing braces around initializer");
4984     }
4985
4986   if (TREE_CODE (constructor_type) == RECORD_TYPE
4987            || TREE_CODE (constructor_type) == UNION_TYPE)
4988     {
4989       constructor_fields = TYPE_FIELDS (constructor_type);
4990       /* Skip any nameless bit fields at the beginning.  */
4991       while (constructor_fields != 0 && DECL_C_BIT_FIELD (constructor_fields)
4992              && DECL_NAME (constructor_fields) == 0)
4993         constructor_fields = TREE_CHAIN (constructor_fields);
4994
4995       constructor_unfilled_fields = constructor_fields;
4996       constructor_bit_index = bitsize_zero_node;
4997     }
4998   else if (TREE_CODE (constructor_type) == VECTOR_TYPE)
4999     {
5000       /* Vectors are like simple fixed-size arrays.  */
5001       constructor_max_index =
5002         build_int_cst (NULL_TREE, TYPE_VECTOR_SUBPARTS (constructor_type) - 1);
5003       constructor_index = convert (bitsizetype, integer_zero_node);
5004       constructor_unfilled_index = constructor_index;
5005     }
5006   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5007     {
5008       if (TYPE_DOMAIN (constructor_type))
5009         {
5010           constructor_max_index
5011             = TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type));
5012
5013           /* Detect non-empty initializations of zero-length arrays.  */
5014           if (constructor_max_index == NULL_TREE
5015               && TYPE_SIZE (constructor_type))
5016             constructor_max_index = build_int_cst (NULL_TREE, -1);
5017
5018           /* constructor_max_index needs to be an INTEGER_CST.  Attempts
5019              to initialize VLAs will cause a proper error; avoid tree
5020              checking errors as well by setting a safe value.  */
5021           if (constructor_max_index
5022               && TREE_CODE (constructor_max_index) != INTEGER_CST)
5023             constructor_max_index = build_int_cst (NULL_TREE, -1);
5024
5025           constructor_index
5026             = convert (bitsizetype,
5027                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
5028         }
5029       else
5030         constructor_index = bitsize_zero_node;
5031
5032       constructor_unfilled_index = constructor_index;
5033       if (value && TREE_CODE (value) == STRING_CST)
5034         {
5035           /* We need to split the char/wchar array into individual
5036              characters, so that we don't have to special case it
5037              everywhere.  */
5038           set_nonincremental_init_from_string (value);
5039         }
5040     }
5041   else
5042     {
5043       if (constructor_type != error_mark_node)
5044         warning_init ("braces around scalar initializer");
5045       constructor_fields = constructor_type;
5046       constructor_unfilled_fields = constructor_type;
5047     }
5048 }
5049
5050 /* At the end of an implicit or explicit brace level,
5051    finish up that level of constructor.  If a single expression
5052    with redundant braces initialized that level, return the
5053    c_expr structure for that expression.  Otherwise, the original_code
5054    element is set to ERROR_MARK.
5055    If we were outputting the elements as they are read, return 0 as the value
5056    from inner levels (process_init_element ignores that),
5057    but return error_mark_node as the value from the outermost level
5058    (that's what we want to put in DECL_INITIAL).
5059    Otherwise, return a CONSTRUCTOR expression as the value.  */
5060
5061 struct c_expr
5062 pop_init_level (int implicit)
5063 {
5064   struct constructor_stack *p;
5065   struct c_expr ret;
5066   ret.value = 0;
5067   ret.original_code = ERROR_MARK;
5068
5069   if (implicit == 0)
5070     {
5071       /* When we come to an explicit close brace,
5072          pop any inner levels that didn't have explicit braces.  */
5073       while (constructor_stack->implicit)
5074         process_init_element (pop_init_level (1));
5075
5076       gcc_assert (!constructor_range_stack);
5077     }
5078
5079   /* Now output all pending elements.  */
5080   constructor_incremental = 1;
5081   output_pending_init_elements (1);
5082
5083   p = constructor_stack;
5084
5085   /* Error for initializing a flexible array member, or a zero-length
5086      array member in an inappropriate context.  */
5087   if (constructor_type && constructor_fields
5088       && TREE_CODE (constructor_type) == ARRAY_TYPE
5089       && TYPE_DOMAIN (constructor_type)
5090       && !TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type)))
5091     {
5092       /* Silently discard empty initializations.  The parser will
5093          already have pedwarned for empty brackets.  */
5094       if (integer_zerop (constructor_unfilled_index))
5095         constructor_type = NULL_TREE;
5096       else
5097         {
5098           gcc_assert (!TYPE_SIZE (constructor_type));
5099
5100           if (constructor_depth > 2)
5101             error_init ("initialization of flexible array member in a nested context");
5102           else if (pedantic)
5103             pedwarn_init ("initialization of a flexible array member");
5104
5105           /* We have already issued an error message for the existence
5106              of a flexible array member not at the end of the structure.
5107              Discard the initializer so that we do not die later.  */
5108           if (TREE_CHAIN (constructor_fields) != NULL_TREE)
5109             constructor_type = NULL_TREE;
5110         }
5111     }
5112
5113   /* Warn when some struct elements are implicitly initialized to zero.  */
5114   if (warn_missing_field_initializers
5115       && constructor_type
5116       && TREE_CODE (constructor_type) == RECORD_TYPE
5117       && constructor_unfilled_fields)
5118     {
5119         /* Do not warn for flexible array members or zero-length arrays.  */
5120         while (constructor_unfilled_fields
5121                && (!DECL_SIZE (constructor_unfilled_fields)
5122                    || integer_zerop (DECL_SIZE (constructor_unfilled_fields))))
5123           constructor_unfilled_fields = TREE_CHAIN (constructor_unfilled_fields);
5124
5125         /* Do not warn if this level of the initializer uses member
5126            designators; it is likely to be deliberate.  */
5127         if (constructor_unfilled_fields && !constructor_designated)
5128           {
5129             push_member_name (constructor_unfilled_fields);
5130             warning_init ("missing initializer");
5131             RESTORE_SPELLING_DEPTH (constructor_depth);
5132           }
5133     }
5134
5135   /* Pad out the end of the structure.  */
5136   if (p->replacement_value.value)
5137     /* If this closes a superfluous brace pair,
5138        just pass out the element between them.  */
5139     ret = p->replacement_value;
5140   else if (constructor_type == 0)
5141     ;
5142   else if (TREE_CODE (constructor_type) != RECORD_TYPE
5143            && TREE_CODE (constructor_type) != UNION_TYPE
5144            && TREE_CODE (constructor_type) != ARRAY_TYPE
5145            && TREE_CODE (constructor_type) != VECTOR_TYPE)
5146     {
5147       /* A nonincremental scalar initializer--just return
5148          the element, after verifying there is just one.  */
5149       if (constructor_elements == 0)
5150         {
5151           if (!constructor_erroneous)
5152             error_init ("empty scalar initializer");
5153           ret.value = error_mark_node;
5154         }
5155       else if (TREE_CHAIN (constructor_elements) != 0)
5156         {
5157           error_init ("extra elements in scalar initializer");
5158           ret.value = TREE_VALUE (constructor_elements);
5159         }
5160       else
5161         ret.value = TREE_VALUE (constructor_elements);
5162     }
5163   else
5164     {
5165       if (constructor_erroneous)
5166         ret.value = error_mark_node;
5167       else
5168         {
5169           ret.value = build_constructor (constructor_type,
5170                                          nreverse (constructor_elements));
5171           if (constructor_constant)
5172             TREE_CONSTANT (ret.value) = TREE_INVARIANT (ret.value) = 1;
5173           if (constructor_constant && constructor_simple)
5174             TREE_STATIC (ret.value) = 1;
5175         }
5176     }
5177
5178   constructor_type = p->type;
5179   constructor_fields = p->fields;
5180   constructor_index = p->index;
5181   constructor_max_index = p->max_index;
5182   constructor_unfilled_index = p->unfilled_index;
5183   constructor_unfilled_fields = p->unfilled_fields;
5184   constructor_bit_index = p->bit_index;
5185   constructor_elements = p->elements;
5186   constructor_constant = p->constant;
5187   constructor_simple = p->simple;
5188   constructor_erroneous = p->erroneous;
5189   constructor_incremental = p->incremental;
5190   constructor_designated = p->designated;
5191   constructor_pending_elts = p->pending_elts;
5192   constructor_depth = p->depth;
5193   if (!p->implicit)
5194     constructor_range_stack = p->range_stack;
5195   RESTORE_SPELLING_DEPTH (constructor_depth);
5196
5197   constructor_stack = p->next;
5198   free (p);
5199
5200   if (ret.value == 0)
5201     {
5202       if (constructor_stack == 0)
5203         {
5204           ret.value = error_mark_node;
5205           return ret;
5206         }
5207       return ret;
5208     }
5209   return ret;
5210 }
5211
5212 /* Common handling for both array range and field name designators.
5213    ARRAY argument is nonzero for array ranges.  Returns zero for success.  */
5214
5215 static int
5216 set_designator (int array)
5217 {
5218   tree subtype;
5219   enum tree_code subcode;
5220
5221   /* Don't die if an entire brace-pair level is superfluous
5222      in the containing level.  */
5223   if (constructor_type == 0)
5224     return 1;
5225
5226   /* If there were errors in this designator list already, bail out
5227      silently.  */
5228   if (designator_errorneous)
5229     return 1;
5230
5231   if (!designator_depth)
5232     {
5233       gcc_assert (!constructor_range_stack);
5234
5235       /* Designator list starts at the level of closest explicit
5236          braces.  */
5237       while (constructor_stack->implicit)
5238         process_init_element (pop_init_level (1));
5239       constructor_designated = 1;
5240       return 0;
5241     }
5242
5243   switch (TREE_CODE (constructor_type))
5244     {
5245     case  RECORD_TYPE:
5246     case  UNION_TYPE:
5247       subtype = TREE_TYPE (constructor_fields);
5248       if (subtype != error_mark_node)
5249         subtype = TYPE_MAIN_VARIANT (subtype);
5250       break;
5251     case ARRAY_TYPE:
5252       subtype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
5253       break;
5254     default:
5255       gcc_unreachable ();
5256     }
5257
5258   subcode = TREE_CODE (subtype);
5259   if (array && subcode != ARRAY_TYPE)
5260     {
5261       error_init ("array index in non-array initializer");
5262       return 1;
5263     }
5264   else if (!array && subcode != RECORD_TYPE && subcode != UNION_TYPE)
5265     {
5266       error_init ("field name not in record or union initializer");
5267       return 1;
5268     }
5269
5270   constructor_designated = 1;
5271   push_init_level (2);
5272   return 0;
5273 }
5274
5275 /* If there are range designators in designator list, push a new designator
5276    to constructor_range_stack.  RANGE_END is end of such stack range or
5277    NULL_TREE if there is no range designator at this level.  */
5278
5279 static void
5280 push_range_stack (tree range_end)
5281 {
5282   struct constructor_range_stack *p;
5283
5284   p = GGC_NEW (struct constructor_range_stack);
5285   p->prev = constructor_range_stack;
5286   p->next = 0;
5287   p->fields = constructor_fields;
5288   p->range_start = constructor_index;
5289   p->index = constructor_index;
5290   p->stack = constructor_stack;
5291   p->range_end = range_end;
5292   if (constructor_range_stack)
5293     constructor_range_stack->next = p;
5294   constructor_range_stack = p;
5295 }
5296
5297 /* Within an array initializer, specify the next index to be initialized.
5298    FIRST is that index.  If LAST is nonzero, then initialize a range
5299    of indices, running from FIRST through LAST.  */
5300
5301 void
5302 set_init_index (tree first, tree last)
5303 {
5304   if (set_designator (1))
5305     return;
5306
5307   designator_errorneous = 1;
5308
5309   if (!INTEGRAL_TYPE_P (TREE_TYPE (first))
5310       || (last && !INTEGRAL_TYPE_P (TREE_TYPE (last))))
5311     {
5312       error_init ("array index in initializer not of integer type");
5313       return;
5314     }
5315
5316   if (TREE_CODE (first) != INTEGER_CST)
5317     error_init ("nonconstant array index in initializer");
5318   else if (last != 0 && TREE_CODE (last) != INTEGER_CST)
5319     error_init ("nonconstant array index in initializer");
5320   else if (TREE_CODE (constructor_type) != ARRAY_TYPE)
5321     error_init ("array index in non-array initializer");
5322   else if (tree_int_cst_sgn (first) == -1)
5323     error_init ("array index in initializer exceeds array bounds");
5324   else if (constructor_max_index
5325            && tree_int_cst_lt (constructor_max_index, first))
5326     error_init ("array index in initializer exceeds array bounds");
5327   else
5328     {
5329       constructor_index = convert (bitsizetype, first);
5330
5331       if (last)
5332         {
5333           if (tree_int_cst_equal (first, last))
5334             last = 0;
5335           else if (tree_int_cst_lt (last, first))
5336             {
5337               error_init ("empty index range in initializer");
5338               last = 0;
5339             }
5340           else
5341             {
5342               last = convert (bitsizetype, last);
5343               if (constructor_max_index != 0
5344                   && tree_int_cst_lt (constructor_max_index, last))
5345                 {
5346                   error_init ("array index range in initializer exceeds array bounds");
5347                   last = 0;
5348                 }
5349             }
5350         }
5351
5352       designator_depth++;
5353       designator_errorneous = 0;
5354       if (constructor_range_stack || last)
5355         push_range_stack (last);
5356     }
5357 }
5358
5359 /* Within a struct initializer, specify the next field to be initialized.  */
5360
5361 void
5362 set_init_label (tree fieldname)
5363 {
5364   tree tail;
5365
5366   if (set_designator (0))
5367     return;
5368
5369   designator_errorneous = 1;
5370
5371   if (TREE_CODE (constructor_type) != RECORD_TYPE
5372       && TREE_CODE (constructor_type) != UNION_TYPE)
5373     {
5374       error_init ("field name not in record or union initializer");
5375       return;
5376     }
5377
5378   for (tail = TYPE_FIELDS (constructor_type); tail;
5379        tail = TREE_CHAIN (tail))
5380     {
5381       if (DECL_NAME (tail) == fieldname)
5382         break;
5383     }
5384
5385   if (tail == 0)
5386     error ("unknown field %qE specified in initializer", fieldname);
5387   else
5388     {
5389       constructor_fields = tail;
5390       designator_depth++;
5391       designator_errorneous = 0;
5392       if (constructor_range_stack)
5393         push_range_stack (NULL_TREE);
5394     }
5395 }
5396 \f
5397 /* Add a new initializer to the tree of pending initializers.  PURPOSE
5398    identifies the initializer, either array index or field in a structure.
5399    VALUE is the value of that index or field.  */
5400
5401 static void
5402 add_pending_init (tree purpose, tree value)
5403 {
5404   struct init_node *p, **q, *r;
5405
5406   q = &constructor_pending_elts;
5407   p = 0;
5408
5409   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5410     {
5411       while (*q != 0)
5412         {
5413           p = *q;
5414           if (tree_int_cst_lt (purpose, p->purpose))
5415             q = &p->left;
5416           else if (tree_int_cst_lt (p->purpose, purpose))
5417             q = &p->right;
5418           else
5419             {
5420               if (TREE_SIDE_EFFECTS (p->value))
5421                 warning_init ("initialized field with side-effects overwritten");
5422               p->value = value;
5423               return;
5424             }
5425         }
5426     }
5427   else
5428     {
5429       tree bitpos;
5430
5431       bitpos = bit_position (purpose);
5432       while (*q != NULL)
5433         {
5434           p = *q;
5435           if (tree_int_cst_lt (bitpos, bit_position (p->purpose)))
5436             q = &p->left;
5437           else if (p->purpose != purpose)
5438             q = &p->right;
5439           else
5440             {
5441               if (TREE_SIDE_EFFECTS (p->value))
5442                 warning_init ("initialized field with side-effects overwritten");
5443               p->value = value;
5444               return;
5445             }
5446         }
5447     }
5448
5449   r = GGC_NEW (struct init_node);
5450   r->purpose = purpose;
5451   r->value = value;
5452
5453   *q = r;
5454   r->parent = p;
5455   r->left = 0;
5456   r->right = 0;
5457   r->balance = 0;
5458
5459   while (p)
5460     {
5461       struct init_node *s;
5462
5463       if (r == p->left)
5464         {
5465           if (p->balance == 0)
5466             p->balance = -1;
5467           else if (p->balance < 0)
5468             {
5469               if (r->balance < 0)
5470                 {
5471                   /* L rotation.  */
5472                   p->left = r->right;
5473                   if (p->left)
5474                     p->left->parent = p;
5475                   r->right = p;
5476
5477                   p->balance = 0;
5478                   r->balance = 0;
5479
5480                   s = p->parent;
5481                   p->parent = r;
5482                   r->parent = s;
5483                   if (s)
5484                     {
5485                       if (s->left == p)
5486                         s->left = r;
5487                       else
5488                         s->right = r;
5489                     }
5490                   else
5491                     constructor_pending_elts = r;
5492                 }
5493               else
5494                 {
5495                   /* LR rotation.  */
5496                   struct init_node *t = r->right;
5497
5498                   r->right = t->left;
5499                   if (r->right)
5500                     r->right->parent = r;
5501                   t->left = r;
5502
5503                   p->left = t->right;
5504                   if (p->left)
5505                     p->left->parent = p;
5506                   t->right = p;
5507
5508                   p->balance = t->balance < 0;
5509                   r->balance = -(t->balance > 0);
5510                   t->balance = 0;
5511
5512                   s = p->parent;
5513                   p->parent = t;
5514                   r->parent = t;
5515                   t->parent = s;
5516                   if (s)
5517                     {
5518                       if (s->left == p)
5519                         s->left = t;
5520                       else
5521                         s->right = t;
5522                     }
5523                   else
5524                     constructor_pending_elts = t;
5525                 }
5526               break;
5527             }
5528           else
5529             {
5530               /* p->balance == +1; growth of left side balances the node.  */
5531               p->balance = 0;
5532               break;
5533             }
5534         }
5535       else /* r == p->right */
5536         {
5537           if (p->balance == 0)
5538             /* Growth propagation from right side.  */
5539             p->balance++;
5540           else if (p->balance > 0)
5541             {
5542               if (r->balance > 0)
5543                 {
5544                   /* R rotation.  */
5545                   p->right = r->left;
5546                   if (p->right)
5547                     p->right->parent = p;
5548                   r->left = p;
5549
5550                   p->balance = 0;
5551                   r->balance = 0;
5552
5553                   s = p->parent;
5554                   p->parent = r;
5555                   r->parent = s;
5556                   if (s)
5557                     {
5558                       if (s->left == p)
5559                         s->left = r;
5560                       else
5561                         s->right = r;
5562                     }
5563                   else
5564                     constructor_pending_elts = r;
5565                 }
5566               else /* r->balance == -1 */
5567                 {
5568                   /* RL rotation */
5569                   struct init_node *t = r->left;
5570
5571                   r->left = t->right;
5572                   if (r->left)
5573                     r->left->parent = r;
5574                   t->right = r;
5575
5576                   p->right = t->left;
5577                   if (p->right)
5578                     p->right->parent = p;
5579                   t->left = p;
5580
5581                   r->balance = (t->balance < 0);
5582                   p->balance = -(t->balance > 0);
5583                   t->balance = 0;
5584
5585                   s = p->parent;
5586                   p->parent = t;
5587                   r->parent = t;
5588                   t->parent = s;
5589                   if (s)
5590                     {
5591                       if (s->left == p)
5592                         s->left = t;
5593                       else
5594                         s->right = t;
5595                     }
5596                   else
5597                     constructor_pending_elts = t;
5598                 }
5599               break;
5600             }
5601           else
5602             {
5603               /* p->balance == -1; growth of right side balances the node.  */
5604               p->balance = 0;
5605               break;
5606             }
5607         }
5608
5609       r = p;
5610       p = p->parent;
5611     }
5612 }
5613
5614 /* Build AVL tree from a sorted chain.  */
5615
5616 static void
5617 set_nonincremental_init (void)
5618 {
5619   tree chain;
5620
5621   if (TREE_CODE (constructor_type) != RECORD_TYPE
5622       && TREE_CODE (constructor_type) != ARRAY_TYPE)
5623     return;
5624
5625   for (chain = constructor_elements; chain; chain = TREE_CHAIN (chain))
5626     add_pending_init (TREE_PURPOSE (chain), TREE_VALUE (chain));
5627   constructor_elements = 0;
5628   if (TREE_CODE (constructor_type) == RECORD_TYPE)
5629     {
5630       constructor_unfilled_fields = TYPE_FIELDS (constructor_type);
5631       /* Skip any nameless bit fields at the beginning.  */
5632       while (constructor_unfilled_fields != 0
5633              && DECL_C_BIT_FIELD (constructor_unfilled_fields)
5634              && DECL_NAME (constructor_unfilled_fields) == 0)
5635         constructor_unfilled_fields = TREE_CHAIN (constructor_unfilled_fields);
5636
5637     }
5638   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5639     {
5640       if (TYPE_DOMAIN (constructor_type))
5641         constructor_unfilled_index
5642             = convert (bitsizetype,
5643                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
5644       else
5645         constructor_unfilled_index = bitsize_zero_node;
5646     }
5647   constructor_incremental = 0;
5648 }
5649
5650 /* Build AVL tree from a string constant.  */
5651
5652 static void
5653 set_nonincremental_init_from_string (tree str)
5654 {
5655   tree value, purpose, type;
5656   HOST_WIDE_INT val[2];
5657   const char *p, *end;
5658   int byte, wchar_bytes, charwidth, bitpos;
5659
5660   gcc_assert (TREE_CODE (constructor_type) == ARRAY_TYPE);
5661
5662   if (TYPE_PRECISION (TREE_TYPE (TREE_TYPE (str)))
5663       == TYPE_PRECISION (char_type_node))
5664     wchar_bytes = 1;
5665   else
5666     {
5667       gcc_assert (TYPE_PRECISION (TREE_TYPE (TREE_TYPE (str)))
5668                   == TYPE_PRECISION (wchar_type_node));
5669       wchar_bytes = TYPE_PRECISION (wchar_type_node) / BITS_PER_UNIT;
5670     }
5671   charwidth = TYPE_PRECISION (char_type_node);
5672   type = TREE_TYPE (constructor_type);
5673   p = TREE_STRING_POINTER (str);
5674   end = p + TREE_STRING_LENGTH (str);
5675
5676   for (purpose = bitsize_zero_node;
5677        p < end && !tree_int_cst_lt (constructor_max_index, purpose);
5678        purpose = size_binop (PLUS_EXPR, purpose, bitsize_one_node))
5679     {
5680       if (wchar_bytes == 1)
5681         {
5682           val[1] = (unsigned char) *p++;
5683           val[0] = 0;
5684         }
5685       else
5686         {
5687           val[0] = 0;
5688           val[1] = 0;
5689           for (byte = 0; byte < wchar_bytes; byte++)
5690             {
5691               if (BYTES_BIG_ENDIAN)
5692                 bitpos = (wchar_bytes - byte - 1) * charwidth;
5693               else
5694                 bitpos = byte * charwidth;
5695               val[bitpos < HOST_BITS_PER_WIDE_INT]
5696                 |= ((unsigned HOST_WIDE_INT) ((unsigned char) *p++))
5697                    << (bitpos % HOST_BITS_PER_WIDE_INT);
5698             }
5699         }
5700
5701       if (!TYPE_UNSIGNED (type))
5702         {
5703           bitpos = ((wchar_bytes - 1) * charwidth) + HOST_BITS_PER_CHAR;
5704           if (bitpos < HOST_BITS_PER_WIDE_INT)
5705             {
5706               if (val[1] & (((HOST_WIDE_INT) 1) << (bitpos - 1)))
5707                 {
5708                   val[1] |= ((HOST_WIDE_INT) -1) << bitpos;
5709                   val[0] = -1;
5710                 }
5711             }
5712           else if (bitpos == HOST_BITS_PER_WIDE_INT)
5713             {
5714               if (val[1] < 0)
5715                 val[0] = -1;
5716             }
5717           else if (val[0] & (((HOST_WIDE_INT) 1)
5718                              << (bitpos - 1 - HOST_BITS_PER_WIDE_INT)))
5719             val[0] |= ((HOST_WIDE_INT) -1)
5720                       << (bitpos - HOST_BITS_PER_WIDE_INT);
5721         }
5722
5723       value = build_int_cst_wide (type, val[1], val[0]);
5724       add_pending_init (purpose, value);
5725     }
5726
5727   constructor_incremental = 0;
5728 }
5729
5730 /* Return value of FIELD in pending initializer or zero if the field was
5731    not initialized yet.  */
5732
5733 static tree
5734 find_init_member (tree field)
5735 {
5736   struct init_node *p;
5737
5738   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5739     {
5740       if (constructor_incremental
5741           && tree_int_cst_lt (field, constructor_unfilled_index))
5742         set_nonincremental_init ();
5743
5744       p = constructor_pending_elts;
5745       while (p)
5746         {
5747           if (tree_int_cst_lt (field, p->purpose))
5748             p = p->left;
5749           else if (tree_int_cst_lt (p->purpose, field))
5750             p = p->right;
5751           else
5752             return p->value;
5753         }
5754     }
5755   else if (TREE_CODE (constructor_type) == RECORD_TYPE)
5756     {
5757       tree bitpos = bit_position (field);
5758
5759       if (constructor_incremental
5760           && (!constructor_unfilled_fields
5761               || tree_int_cst_lt (bitpos,
5762                                   bit_position (constructor_unfilled_fields))))
5763         set_nonincremental_init ();
5764
5765       p = constructor_pending_elts;
5766       while (p)
5767         {
5768           if (field == p->purpose)
5769             return p->value;
5770           else if (tree_int_cst_lt (bitpos, bit_position (p->purpose)))
5771             p = p->left;
5772           else
5773             p = p->right;
5774         }
5775     }
5776   else if (TREE_CODE (constructor_type) == UNION_TYPE)
5777     {
5778       if (constructor_elements
5779           && TREE_PURPOSE (constructor_elements) == field)
5780         return TREE_VALUE (constructor_elements);
5781     }
5782   return 0;
5783 }
5784
5785 /* "Output" the next constructor element.
5786    At top level, really output it to assembler code now.
5787    Otherwise, collect it in a list from which we will make a CONSTRUCTOR.
5788    TYPE is the data type that the containing data type wants here.
5789    FIELD is the field (a FIELD_DECL) or the index that this element fills.
5790    If VALUE is a string constant, STRICT_STRING is true if it is
5791    unparenthesized or we should not warn here for it being parenthesized.
5792    For other types of VALUE, STRICT_STRING is not used.
5793
5794    PENDING if non-nil means output pending elements that belong
5795    right after this element.  (PENDING is normally 1;
5796    it is 0 while outputting pending elements, to avoid recursion.)  */
5797
5798 static void
5799 output_init_element (tree value, bool strict_string, tree type, tree field,
5800                      int pending)
5801 {
5802   if (type == error_mark_node || value == error_mark_node)
5803     {
5804       constructor_erroneous = 1;
5805       return;
5806     }
5807   if (TREE_CODE (TREE_TYPE (value)) == ARRAY_TYPE
5808       && (TREE_CODE (value) == STRING_CST
5809           || TREE_CODE (value) == COMPOUND_LITERAL_EXPR)
5810       && !(TREE_CODE (value) == STRING_CST
5811            && TREE_CODE (type) == ARRAY_TYPE
5812            && INTEGRAL_TYPE_P (TREE_TYPE (type)))
5813       && !comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (value)),
5814                      TYPE_MAIN_VARIANT (type)))
5815     value = array_to_pointer_conversion (value);
5816
5817   if (TREE_CODE (value) == COMPOUND_LITERAL_EXPR
5818       && require_constant_value && !flag_isoc99 && pending)
5819     {
5820       /* As an extension, allow initializing objects with static storage
5821          duration with compound literals (which are then treated just as
5822          the brace enclosed list they contain).  */
5823       tree decl = COMPOUND_LITERAL_EXPR_DECL (value);
5824       value = DECL_INITIAL (decl);
5825     }
5826
5827   if (value == error_mark_node)
5828     constructor_erroneous = 1;
5829   else if (!TREE_CONSTANT (value))
5830     constructor_constant = 0;
5831   else if (!initializer_constant_valid_p (value, TREE_TYPE (value))
5832            || ((TREE_CODE (constructor_type) == RECORD_TYPE
5833                 || TREE_CODE (constructor_type) == UNION_TYPE)
5834                && DECL_C_BIT_FIELD (field)
5835                && TREE_CODE (value) != INTEGER_CST))
5836     constructor_simple = 0;
5837
5838   if (!initializer_constant_valid_p (value, TREE_TYPE (value)))
5839     {
5840       if (require_constant_value)
5841         {
5842           error_init ("initializer element is not constant");
5843           value = error_mark_node;
5844         }
5845       else if (require_constant_elements)
5846         pedwarn ("initializer element is not computable at load time");
5847     }
5848
5849   /* If this field is empty (and not at the end of structure),
5850      don't do anything other than checking the initializer.  */
5851   if (field
5852       && (TREE_TYPE (field) == error_mark_node
5853           || (COMPLETE_TYPE_P (TREE_TYPE (field))
5854               && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))
5855               && (TREE_CODE (constructor_type) == ARRAY_TYPE
5856                   || TREE_CHAIN (field)))))
5857     return;
5858
5859   value = digest_init (type, value, strict_string, require_constant_value);
5860   if (value == error_mark_node)
5861     {
5862       constructor_erroneous = 1;
5863       return;
5864     }
5865
5866   /* If this element doesn't come next in sequence,
5867      put it on constructor_pending_elts.  */
5868   if (TREE_CODE (constructor_type) == ARRAY_TYPE
5869       && (!constructor_incremental
5870           || !tree_int_cst_equal (field, constructor_unfilled_index)))
5871     {
5872       if (constructor_incremental
5873           && tree_int_cst_lt (field, constructor_unfilled_index))
5874         set_nonincremental_init ();
5875
5876       add_pending_init (field, value);
5877       return;
5878     }
5879   else if (TREE_CODE (constructor_type) == RECORD_TYPE
5880            && (!constructor_incremental
5881                || field != constructor_unfilled_fields))
5882     {
5883       /* We do this for records but not for unions.  In a union,
5884          no matter which field is specified, it can be initialized
5885          right away since it starts at the beginning of the union.  */
5886       if (constructor_incremental)
5887         {
5888           if (!constructor_unfilled_fields)
5889             set_nonincremental_init ();
5890           else
5891             {
5892               tree bitpos, unfillpos;
5893
5894               bitpos = bit_position (field);
5895               unfillpos = bit_position (constructor_unfilled_fields);
5896
5897               if (tree_int_cst_lt (bitpos, unfillpos))
5898                 set_nonincremental_init ();
5899             }
5900         }
5901
5902       add_pending_init (field, value);
5903       return;
5904     }
5905   else if (TREE_CODE (constructor_type) == UNION_TYPE
5906            && constructor_elements)
5907     {
5908       if (TREE_SIDE_EFFECTS (TREE_VALUE (constructor_elements)))
5909         warning_init ("initialized field with side-effects overwritten");
5910
5911       /* We can have just one union field set.  */
5912       constructor_elements = 0;
5913     }
5914
5915   /* Otherwise, output this element either to
5916      constructor_elements or to the assembler file.  */
5917
5918   if (field && TREE_CODE (field) == INTEGER_CST)
5919     field = copy_node (field);
5920   constructor_elements
5921     = tree_cons (field, value, constructor_elements);
5922
5923   /* Advance the variable that indicates sequential elements output.  */
5924   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5925     constructor_unfilled_index
5926       = size_binop (PLUS_EXPR, constructor_unfilled_index,
5927                     bitsize_one_node);
5928   else if (TREE_CODE (constructor_type) == RECORD_TYPE)
5929     {
5930       constructor_unfilled_fields
5931         = TREE_CHAIN (constructor_unfilled_fields);
5932
5933       /* Skip any nameless bit fields.  */
5934       while (constructor_unfilled_fields != 0
5935              && DECL_C_BIT_FIELD (constructor_unfilled_fields)
5936              && DECL_NAME (constructor_unfilled_fields) == 0)
5937         constructor_unfilled_fields =
5938           TREE_CHAIN (constructor_unfilled_fields);
5939     }
5940   else if (TREE_CODE (constructor_type) == UNION_TYPE)
5941     constructor_unfilled_fields = 0;
5942
5943   /* Now output any pending elements which have become next.  */
5944   if (pending)
5945     output_pending_init_elements (0);
5946 }
5947
5948 /* Output any pending elements which have become next.
5949    As we output elements, constructor_unfilled_{fields,index}
5950    advances, which may cause other elements to become next;
5951    if so, they too are output.
5952
5953    If ALL is 0, we return when there are
5954    no more pending elements to output now.
5955
5956    If ALL is 1, we output space as necessary so that
5957    we can output all the pending elements.  */
5958
5959 static void
5960 output_pending_init_elements (int all)
5961 {
5962   struct init_node *elt = constructor_pending_elts;
5963   tree next;
5964
5965  retry:
5966
5967   /* Look through the whole pending tree.
5968      If we find an element that should be output now,
5969      output it.  Otherwise, set NEXT to the element
5970      that comes first among those still pending.  */
5971
5972   next = 0;
5973   while (elt)
5974     {
5975       if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5976         {
5977           if (tree_int_cst_equal (elt->purpose,
5978                                   constructor_unfilled_index))
5979             output_init_element (elt->value, true,
5980                                  TREE_TYPE (constructor_type),
5981                                  constructor_unfilled_index, 0);
5982           else if (tree_int_cst_lt (constructor_unfilled_index,
5983                                     elt->purpose))
5984             {
5985               /* Advance to the next smaller node.  */
5986               if (elt->left)
5987                 elt = elt->left;
5988               else
5989                 {
5990                   /* We have reached the smallest node bigger than the
5991                      current unfilled index.  Fill the space first.  */
5992                   next = elt->purpose;
5993                   break;
5994                 }
5995             }
5996           else
5997             {
5998               /* Advance to the next bigger node.  */
5999               if (elt->right)
6000                 elt = elt->right;
6001               else
6002                 {
6003                   /* We have reached the biggest node in a subtree.  Find
6004                      the parent of it, which is the next bigger node.  */
6005                   while (elt->parent && elt->parent->right == elt)
6006                     elt = elt->parent;
6007                   elt = elt->parent;
6008                   if (elt && tree_int_cst_lt (constructor_unfilled_index,
6009                                               elt->purpose))
6010                     {
6011                       next = elt->purpose;
6012                       break;
6013                     }
6014                 }
6015             }
6016         }
6017       else if (TREE_CODE (constructor_type) == RECORD_TYPE
6018                || TREE_CODE (constructor_type) == UNION_TYPE)
6019         {
6020           tree ctor_unfilled_bitpos, elt_bitpos;
6021
6022           /* If the current record is complete we are done.  */
6023           if (constructor_unfilled_fields == 0)
6024             break;
6025
6026           ctor_unfilled_bitpos = bit_position (constructor_unfilled_fields);
6027           elt_bitpos = bit_position (elt->purpose);
6028           /* We can't compare fields here because there might be empty
6029              fields in between.  */
6030           if (tree_int_cst_equal (elt_bitpos, ctor_unfilled_bitpos))
6031             {
6032               constructor_unfilled_fields = elt->purpose;
6033               output_init_element (elt->value, true, TREE_TYPE (elt->purpose),
6034                                    elt->purpose, 0);
6035             }
6036           else if (tree_int_cst_lt (ctor_unfilled_bitpos, elt_bitpos))
6037             {
6038               /* Advance to the next smaller node.  */
6039               if (elt->left)
6040                 elt = elt->left;
6041               else
6042                 {
6043                   /* We have reached the smallest node bigger than the
6044                      current unfilled field.  Fill the space first.  */
6045                   next = elt->purpose;
6046                   break;
6047                 }
6048             }
6049           else
6050             {
6051               /* Advance to the next bigger node.  */
6052               if (elt->right)
6053                 elt = elt->right;
6054               else
6055                 {
6056                   /* We have reached the biggest node in a subtree.  Find
6057                      the parent of it, which is the next bigger node.  */
6058                   while (elt->parent && elt->parent->right == elt)
6059                     elt = elt->parent;
6060                   elt = elt->parent;
6061                   if (elt
6062                       && (tree_int_cst_lt (ctor_unfilled_bitpos,
6063                                            bit_position (elt->purpose))))
6064                     {
6065                       next = elt->purpose;
6066                       break;
6067                     }
6068                 }
6069             }
6070         }
6071     }
6072
6073   /* Ordinarily return, but not if we want to output all
6074      and there are elements left.  */
6075   if (!(all && next != 0))
6076     return;
6077
6078   /* If it's not incremental, just skip over the gap, so that after
6079      jumping to retry we will output the next successive element.  */
6080   if (TREE_CODE (constructor_type) == RECORD_TYPE
6081       || TREE_CODE (constructor_type) == UNION_TYPE)
6082     constructor_unfilled_fields = next;
6083   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6084     constructor_unfilled_index = next;
6085
6086   /* ELT now points to the node in the pending tree with the next
6087      initializer to output.  */
6088   goto retry;
6089 }
6090 \f
6091 /* Add one non-braced element to the current constructor level.
6092    This adjusts the current position within the constructor's type.
6093    This may also start or terminate implicit levels
6094    to handle a partly-braced initializer.
6095
6096    Once this has found the correct level for the new element,
6097    it calls output_init_element.  */
6098
6099 void
6100 process_init_element (struct c_expr value)
6101 {
6102   tree orig_value = value.value;
6103   int string_flag = orig_value != 0 && TREE_CODE (orig_value) == STRING_CST;
6104   bool strict_string = value.original_code == STRING_CST;
6105
6106   designator_depth = 0;
6107   designator_errorneous = 0;
6108
6109   /* Handle superfluous braces around string cst as in
6110      char x[] = {"foo"}; */
6111   if (string_flag
6112       && constructor_type
6113       && TREE_CODE (constructor_type) == ARRAY_TYPE
6114       && INTEGRAL_TYPE_P (TREE_TYPE (constructor_type))
6115       && integer_zerop (constructor_unfilled_index))
6116     {
6117       if (constructor_stack->replacement_value.value)
6118         error_init ("excess elements in char array initializer");
6119       constructor_stack->replacement_value = value;
6120       return;
6121     }
6122
6123   if (constructor_stack->replacement_value.value != 0)
6124     {
6125       error_init ("excess elements in struct initializer");
6126       return;
6127     }
6128
6129   /* Ignore elements of a brace group if it is entirely superfluous
6130      and has already been diagnosed.  */
6131   if (constructor_type == 0)
6132     return;
6133
6134   /* If we've exhausted any levels that didn't have braces,
6135      pop them now.  */
6136   while (constructor_stack->implicit)
6137     {
6138       if ((TREE_CODE (constructor_type) == RECORD_TYPE
6139            || TREE_CODE (constructor_type) == UNION_TYPE)
6140           && constructor_fields == 0)
6141         process_init_element (pop_init_level (1));
6142       else if (TREE_CODE (constructor_type) == ARRAY_TYPE
6143                && (constructor_max_index == 0
6144                    || tree_int_cst_lt (constructor_max_index,
6145                                        constructor_index)))
6146         process_init_element (pop_init_level (1));
6147       else
6148         break;
6149     }
6150
6151   /* In the case of [LO ... HI] = VALUE, only evaluate VALUE once.  */
6152   if (constructor_range_stack)
6153     {
6154       /* If value is a compound literal and we'll be just using its
6155          content, don't put it into a SAVE_EXPR.  */
6156       if (TREE_CODE (value.value) != COMPOUND_LITERAL_EXPR
6157           || !require_constant_value
6158           || flag_isoc99)
6159         value.value = save_expr (value.value);
6160     }
6161
6162   while (1)
6163     {
6164       if (TREE_CODE (constructor_type) == RECORD_TYPE)
6165         {
6166           tree fieldtype;
6167           enum tree_code fieldcode;
6168
6169           if (constructor_fields == 0)
6170             {
6171               pedwarn_init ("excess elements in struct initializer");
6172               break;
6173             }
6174
6175           fieldtype = TREE_TYPE (constructor_fields);
6176           if (fieldtype != error_mark_node)
6177             fieldtype = TYPE_MAIN_VARIANT (fieldtype);
6178           fieldcode = TREE_CODE (fieldtype);
6179
6180           /* Error for non-static initialization of a flexible array member.  */
6181           if (fieldcode == ARRAY_TYPE
6182               && !require_constant_value
6183               && TYPE_SIZE (fieldtype) == NULL_TREE
6184               && TREE_CHAIN (constructor_fields) == NULL_TREE)
6185             {
6186               error_init ("non-static initialization of a flexible array member");
6187               break;
6188             }
6189
6190           /* Accept a string constant to initialize a subarray.  */
6191           if (value.value != 0
6192               && fieldcode == ARRAY_TYPE
6193               && INTEGRAL_TYPE_P (TREE_TYPE (fieldtype))
6194               && string_flag)
6195             value.value = orig_value;
6196           /* Otherwise, if we have come to a subaggregate,
6197              and we don't have an element of its type, push into it.  */
6198           else if (value.value != 0
6199                    && value.value != error_mark_node
6200                    && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != fieldtype
6201                    && (fieldcode == RECORD_TYPE || fieldcode == ARRAY_TYPE
6202                        || fieldcode == UNION_TYPE))
6203             {
6204               push_init_level (1);
6205               continue;
6206             }
6207
6208           if (value.value)
6209             {
6210               push_member_name (constructor_fields);
6211               output_init_element (value.value, strict_string,
6212                                    fieldtype, constructor_fields, 1);
6213               RESTORE_SPELLING_DEPTH (constructor_depth);
6214             }
6215           else
6216             /* Do the bookkeeping for an element that was
6217                directly output as a constructor.  */
6218             {
6219               /* For a record, keep track of end position of last field.  */
6220               if (DECL_SIZE (constructor_fields))
6221                 constructor_bit_index
6222                   = size_binop (PLUS_EXPR,
6223                                 bit_position (constructor_fields),
6224                                 DECL_SIZE (constructor_fields));
6225
6226               /* If the current field was the first one not yet written out,
6227                  it isn't now, so update.  */
6228               if (constructor_unfilled_fields == constructor_fields)
6229                 {
6230                   constructor_unfilled_fields = TREE_CHAIN (constructor_fields);
6231                   /* Skip any nameless bit fields.  */
6232                   while (constructor_unfilled_fields != 0
6233                          && DECL_C_BIT_FIELD (constructor_unfilled_fields)
6234                          && DECL_NAME (constructor_unfilled_fields) == 0)
6235                     constructor_unfilled_fields =
6236                       TREE_CHAIN (constructor_unfilled_fields);
6237                 }
6238             }
6239
6240           constructor_fields = TREE_CHAIN (constructor_fields);
6241           /* Skip any nameless bit fields at the beginning.  */
6242           while (constructor_fields != 0
6243                  && DECL_C_BIT_FIELD (constructor_fields)
6244                  && DECL_NAME (constructor_fields) == 0)
6245             constructor_fields = TREE_CHAIN (constructor_fields);
6246         }
6247       else if (TREE_CODE (constructor_type) == UNION_TYPE)
6248         {
6249           tree fieldtype;
6250           enum tree_code fieldcode;
6251
6252           if (constructor_fields == 0)
6253             {
6254               pedwarn_init ("excess elements in union initializer");
6255               break;
6256             }
6257
6258           fieldtype = TREE_TYPE (constructor_fields);
6259           if (fieldtype != error_mark_node)
6260             fieldtype = TYPE_MAIN_VARIANT (fieldtype);
6261           fieldcode = TREE_CODE (fieldtype);
6262
6263           /* Warn that traditional C rejects initialization of unions.
6264              We skip the warning if the value is zero.  This is done
6265              under the assumption that the zero initializer in user
6266              code appears conditioned on e.g. __STDC__ to avoid
6267              "missing initializer" warnings and relies on default
6268              initialization to zero in the traditional C case.
6269              We also skip the warning if the initializer is designated,
6270              again on the assumption that this must be conditional on
6271              __STDC__ anyway (and we've already complained about the
6272              member-designator already).  */
6273           if (!in_system_header && !constructor_designated
6274               && !(value.value && (integer_zerop (value.value)
6275                                    || real_zerop (value.value))))
6276             warning (OPT_Wtraditional, "traditional C rejects initialization "
6277                      "of unions");
6278
6279           /* Accept a string constant to initialize a subarray.  */
6280           if (value.value != 0
6281               && fieldcode == ARRAY_TYPE
6282               && INTEGRAL_TYPE_P (TREE_TYPE (fieldtype))
6283               && string_flag)
6284             value.value = orig_value;
6285           /* Otherwise, if we have come to a subaggregate,
6286              and we don't have an element of its type, push into it.  */
6287           else if (value.value != 0
6288                    && value.value != error_mark_node
6289                    && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != fieldtype
6290                    && (fieldcode == RECORD_TYPE || fieldcode == ARRAY_TYPE
6291                        || fieldcode == UNION_TYPE))
6292             {
6293               push_init_level (1);
6294               continue;
6295             }
6296
6297           if (value.value)
6298             {
6299               push_member_name (constructor_fields);
6300               output_init_element (value.value, strict_string,
6301                                    fieldtype, constructor_fields, 1);
6302               RESTORE_SPELLING_DEPTH (constructor_depth);
6303             }
6304           else
6305             /* Do the bookkeeping for an element that was
6306                directly output as a constructor.  */
6307             {
6308               constructor_bit_index = DECL_SIZE (constructor_fields);
6309               constructor_unfilled_fields = TREE_CHAIN (constructor_fields);
6310             }
6311
6312           constructor_fields = 0;
6313         }
6314       else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6315         {
6316           tree elttype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
6317           enum tree_code eltcode = TREE_CODE (elttype);
6318
6319           /* Accept a string constant to initialize a subarray.  */
6320           if (value.value != 0
6321               && eltcode == ARRAY_TYPE
6322               && INTEGRAL_TYPE_P (TREE_TYPE (elttype))
6323               && string_flag)
6324             value.value = orig_value;
6325           /* Otherwise, if we have come to a subaggregate,
6326              and we don't have an element of its type, push into it.  */
6327           else if (value.value != 0
6328                    && value.value != error_mark_node
6329                    && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != elttype
6330                    && (eltcode == RECORD_TYPE || eltcode == ARRAY_TYPE
6331                        || eltcode == UNION_TYPE))
6332             {
6333               push_init_level (1);
6334               continue;
6335             }
6336
6337           if (constructor_max_index != 0
6338               && (tree_int_cst_lt (constructor_max_index, constructor_index)
6339                   || integer_all_onesp (constructor_max_index)))
6340             {
6341               pedwarn_init ("excess elements in array initializer");
6342               break;
6343             }
6344
6345           /* Now output the actual element.  */
6346           if (value.value)
6347             {
6348               push_array_bounds (tree_low_cst (constructor_index, 0));
6349               output_init_element (value.value, strict_string,
6350                                    elttype, constructor_index, 1);
6351               RESTORE_SPELLING_DEPTH (constructor_depth);
6352             }
6353
6354           constructor_index
6355             = size_binop (PLUS_EXPR, constructor_index, bitsize_one_node);
6356
6357           if (!value.value)
6358             /* If we are doing the bookkeeping for an element that was
6359                directly output as a constructor, we must update
6360                constructor_unfilled_index.  */
6361             constructor_unfilled_index = constructor_index;
6362         }
6363       else if (TREE_CODE (constructor_type) == VECTOR_TYPE)
6364         {
6365           tree elttype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
6366
6367          /* Do a basic check of initializer size.  Note that vectors
6368             always have a fixed size derived from their type.  */
6369           if (tree_int_cst_lt (constructor_max_index, constructor_index))
6370             {
6371               pedwarn_init ("excess elements in vector initializer");
6372               break;
6373             }
6374
6375           /* Now output the actual element.  */
6376           if (value.value)
6377             output_init_element (value.value, strict_string,
6378                                  elttype, constructor_index, 1);
6379
6380           constructor_index
6381             = size_binop (PLUS_EXPR, constructor_index, bitsize_one_node);
6382
6383           if (!value.value)
6384             /* If we are doing the bookkeeping for an element that was
6385                directly output as a constructor, we must update
6386                constructor_unfilled_index.  */
6387             constructor_unfilled_index = constructor_index;
6388         }
6389
6390       /* Handle the sole element allowed in a braced initializer
6391          for a scalar variable.  */
6392       else if (constructor_type != error_mark_node
6393                && constructor_fields == 0)
6394         {
6395           pedwarn_init ("excess elements in scalar initializer");
6396           break;
6397         }
6398       else
6399         {
6400           if (value.value)
6401             output_init_element (value.value, strict_string,
6402                                  constructor_type, NULL_TREE, 1);
6403           constructor_fields = 0;
6404         }
6405
6406       /* Handle range initializers either at this level or anywhere higher
6407          in the designator stack.  */
6408       if (constructor_range_stack)
6409         {
6410           struct constructor_range_stack *p, *range_stack;
6411           int finish = 0;
6412
6413           range_stack = constructor_range_stack;
6414           constructor_range_stack = 0;
6415           while (constructor_stack != range_stack->stack)
6416             {
6417               gcc_assert (constructor_stack->implicit);
6418               process_init_element (pop_init_level (1));
6419             }
6420           for (p = range_stack;
6421                !p->range_end || tree_int_cst_equal (p->index, p->range_end);
6422                p = p->prev)
6423             {
6424               gcc_assert (constructor_stack->implicit);
6425               process_init_element (pop_init_level (1));
6426             }
6427
6428           p->index = size_binop (PLUS_EXPR, p->index, bitsize_one_node);
6429           if (tree_int_cst_equal (p->index, p->range_end) && !p->prev)
6430             finish = 1;
6431
6432           while (1)
6433             {
6434               constructor_index = p->index;
6435               constructor_fields = p->fields;
6436               if (finish && p->range_end && p->index == p->range_start)
6437                 {
6438                   finish = 0;
6439                   p->prev = 0;
6440                 }
6441               p = p->next;
6442               if (!p)
6443                 break;
6444               push_init_level (2);
6445               p->stack = constructor_stack;
6446               if (p->range_end && tree_int_cst_equal (p->index, p->range_end))
6447                 p->index = p->range_start;
6448             }
6449
6450           if (!finish)
6451             constructor_range_stack = range_stack;
6452           continue;
6453         }
6454
6455       break;
6456     }
6457
6458   constructor_range_stack = 0;
6459 }
6460 \f
6461 /* Build a complete asm-statement, whose components are a CV_QUALIFIER
6462    (guaranteed to be 'volatile' or null) and ARGS (represented using
6463    an ASM_EXPR node).  */
6464 tree
6465 build_asm_stmt (tree cv_qualifier, tree args)
6466 {
6467   if (!ASM_VOLATILE_P (args) && cv_qualifier)
6468     ASM_VOLATILE_P (args) = 1;
6469   return add_stmt (args);
6470 }
6471
6472 /* Build an asm-expr, whose components are a STRING, some OUTPUTS,
6473    some INPUTS, and some CLOBBERS.  The latter three may be NULL.
6474    SIMPLE indicates whether there was anything at all after the
6475    string in the asm expression -- asm("blah") and asm("blah" : )
6476    are subtly different.  We use a ASM_EXPR node to represent this.  */
6477 tree
6478 build_asm_expr (tree string, tree outputs, tree inputs, tree clobbers,
6479                 bool simple)
6480 {
6481   tree tail;
6482   tree args;
6483   int i;
6484   const char *constraint;
6485   const char **oconstraints;
6486   bool allows_mem, allows_reg, is_inout;
6487   int ninputs, noutputs;
6488
6489   ninputs = list_length (inputs);
6490   noutputs = list_length (outputs);
6491   oconstraints = (const char **) alloca (noutputs * sizeof (const char *));
6492
6493   string = resolve_asm_operand_names (string, outputs, inputs);
6494
6495   /* Remove output conversions that change the type but not the mode.  */
6496   for (i = 0, tail = outputs; tail; ++i, tail = TREE_CHAIN (tail))
6497     {
6498       tree output = TREE_VALUE (tail);
6499
6500       /* ??? Really, this should not be here.  Users should be using a
6501          proper lvalue, dammit.  But there's a long history of using casts
6502          in the output operands.  In cases like longlong.h, this becomes a
6503          primitive form of typechecking -- if the cast can be removed, then
6504          the output operand had a type of the proper width; otherwise we'll
6505          get an error.  Gross, but ...  */
6506       STRIP_NOPS (output);
6507
6508       if (!lvalue_or_else (output, lv_asm))
6509         output = error_mark_node;
6510
6511       constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tail)));
6512       oconstraints[i] = constraint;
6513
6514       if (parse_output_constraint (&constraint, i, ninputs, noutputs,
6515                                    &allows_mem, &allows_reg, &is_inout))
6516         {
6517           /* If the operand is going to end up in memory,
6518              mark it addressable.  */
6519           if (!allows_reg && !c_mark_addressable (output))
6520             output = error_mark_node;
6521         }
6522       else
6523         output = error_mark_node;
6524
6525       TREE_VALUE (tail) = output;
6526     }
6527
6528   for (i = 0, tail = inputs; tail; ++i, tail = TREE_CHAIN (tail))
6529     {
6530       tree input;
6531
6532       constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tail)));
6533       input = TREE_VALUE (tail);
6534
6535       if (parse_input_constraint (&constraint, i, ninputs, noutputs, 0,
6536                                   oconstraints, &allows_mem, &allows_reg))
6537         {
6538           /* If the operand is going to end up in memory,
6539              mark it addressable.  */
6540           if (!allows_reg && allows_mem)
6541             {
6542               /* Strip the nops as we allow this case.  FIXME, this really
6543                  should be rejected or made deprecated.  */
6544               STRIP_NOPS (input);
6545               if (!c_mark_addressable (input))
6546                 input = error_mark_node;
6547           }
6548         }
6549       else
6550         input = error_mark_node;
6551
6552       TREE_VALUE (tail) = input;
6553     }
6554
6555   args = build_stmt (ASM_EXPR, string, outputs, inputs, clobbers);
6556
6557   /* Simple asm statements are treated as volatile.  */
6558   if (simple)
6559     {
6560       ASM_VOLATILE_P (args) = 1;
6561       ASM_INPUT_P (args) = 1;
6562     }
6563
6564   return args;
6565 }
6566 \f
6567 /* Generate a goto statement to LABEL.  */
6568
6569 tree
6570 c_finish_goto_label (tree label)
6571 {
6572   tree decl = lookup_label (label);
6573   if (!decl)
6574     return NULL_TREE;
6575
6576   if (C_DECL_UNJUMPABLE_STMT_EXPR (decl))
6577     {
6578       error ("jump into statement expression");
6579       return NULL_TREE;
6580     }
6581
6582   if (C_DECL_UNJUMPABLE_VM (decl))
6583     {
6584       error ("jump into scope of identifier with variably modified type");
6585       return NULL_TREE;
6586     }
6587
6588   if (!C_DECL_UNDEFINABLE_STMT_EXPR (decl))
6589     {
6590       /* No jump from outside this statement expression context, so
6591          record that there is a jump from within this context.  */
6592       struct c_label_list *nlist;
6593       nlist = XOBNEW (&parser_obstack, struct c_label_list);
6594       nlist->next = label_context_stack_se->labels_used;
6595       nlist->label = decl;
6596       label_context_stack_se->labels_used = nlist;
6597     }
6598
6599   if (!C_DECL_UNDEFINABLE_VM (decl))
6600     {
6601       /* No jump from outside this context context of identifiers with
6602          variably modified type, so record that there is a jump from
6603          within this context.  */
6604       struct c_label_list *nlist;
6605       nlist = XOBNEW (&parser_obstack, struct c_label_list);
6606       nlist->next = label_context_stack_vm->labels_used;
6607       nlist->label = decl;
6608       label_context_stack_vm->labels_used = nlist;
6609     }
6610
6611   TREE_USED (decl) = 1;
6612   return add_stmt (build1 (GOTO_EXPR, void_type_node, decl));
6613 }
6614
6615 /* Generate a computed goto statement to EXPR.  */
6616
6617 tree
6618 c_finish_goto_ptr (tree expr)
6619 {
6620   if (pedantic)
6621     pedwarn ("ISO C forbids %<goto *expr;%>");
6622   expr = convert (ptr_type_node, expr);
6623   return add_stmt (build1 (GOTO_EXPR, void_type_node, expr));
6624 }
6625
6626 /* Generate a C `return' statement.  RETVAL is the expression for what
6627    to return, or a null pointer for `return;' with no value.  */
6628
6629 tree
6630 c_finish_return (tree retval)
6631 {
6632   tree valtype = TREE_TYPE (TREE_TYPE (current_function_decl));
6633
6634   if (TREE_THIS_VOLATILE (current_function_decl))
6635     warning (0, "function declared %<noreturn%> has a %<return%> statement");
6636
6637   if (!retval)
6638     {
6639       current_function_returns_null = 1;
6640       if ((warn_return_type || flag_isoc99)
6641           && valtype != 0 && TREE_CODE (valtype) != VOID_TYPE)
6642         pedwarn_c99 ("%<return%> with no value, in "
6643                      "function returning non-void");
6644     }
6645   else if (valtype == 0 || TREE_CODE (valtype) == VOID_TYPE)
6646     {
6647       current_function_returns_null = 1;
6648       if (pedantic || TREE_CODE (TREE_TYPE (retval)) != VOID_TYPE)
6649         pedwarn ("%<return%> with a value, in function returning void");
6650     }
6651   else
6652     {
6653       tree t = convert_for_assignment (valtype, retval, ic_return,
6654                                        NULL_TREE, NULL_TREE, 0);
6655       tree res = DECL_RESULT (current_function_decl);
6656       tree inner;
6657
6658       current_function_returns_value = 1;
6659       if (t == error_mark_node)
6660         return NULL_TREE;
6661
6662       inner = t = convert (TREE_TYPE (res), t);
6663
6664       /* Strip any conversions, additions, and subtractions, and see if
6665          we are returning the address of a local variable.  Warn if so.  */
6666       while (1)
6667         {
6668           switch (TREE_CODE (inner))
6669             {
6670             case NOP_EXPR:   case NON_LVALUE_EXPR:  case CONVERT_EXPR:
6671             case PLUS_EXPR:
6672               inner = TREE_OPERAND (inner, 0);
6673               continue;
6674
6675             case MINUS_EXPR:
6676               /* If the second operand of the MINUS_EXPR has a pointer
6677                  type (or is converted from it), this may be valid, so
6678                  don't give a warning.  */
6679               {
6680                 tree op1 = TREE_OPERAND (inner, 1);
6681
6682                 while (!POINTER_TYPE_P (TREE_TYPE (op1))
6683                        && (TREE_CODE (op1) == NOP_EXPR
6684                            || TREE_CODE (op1) == NON_LVALUE_EXPR
6685                            || TREE_CODE (op1) == CONVERT_EXPR))
6686                   op1 = TREE_OPERAND (op1, 0);
6687
6688                 if (POINTER_TYPE_P (TREE_TYPE (op1)))
6689                   break;
6690
6691                 inner = TREE_OPERAND (inner, 0);
6692                 continue;
6693               }
6694
6695             case ADDR_EXPR:
6696               inner = TREE_OPERAND (inner, 0);
6697
6698               while (REFERENCE_CLASS_P (inner)
6699                      && TREE_CODE (inner) != INDIRECT_REF)
6700                 inner = TREE_OPERAND (inner, 0);
6701
6702               if (DECL_P (inner)
6703                   && !DECL_EXTERNAL (inner)
6704                   && !TREE_STATIC (inner)
6705                   && DECL_CONTEXT (inner) == current_function_decl)
6706                 warning (0, "function returns address of local variable");
6707               break;
6708
6709             default:
6710               break;
6711             }
6712
6713           break;
6714         }
6715
6716       retval = build2 (MODIFY_EXPR, TREE_TYPE (res), res, t);
6717     }
6718
6719   return add_stmt (build_stmt (RETURN_EXPR, retval));
6720 }
6721 \f
6722 struct c_switch {
6723   /* The SWITCH_EXPR being built.  */
6724   tree switch_expr;
6725
6726   /* The original type of the testing expression, i.e. before the
6727      default conversion is applied.  */
6728   tree orig_type;
6729
6730   /* A splay-tree mapping the low element of a case range to the high
6731      element, or NULL_TREE if there is no high element.  Used to
6732      determine whether or not a new case label duplicates an old case
6733      label.  We need a tree, rather than simply a hash table, because
6734      of the GNU case range extension.  */
6735   splay_tree cases;
6736
6737   /* Number of nested statement expressions within this switch
6738      statement; if nonzero, case and default labels may not
6739      appear.  */
6740   unsigned int blocked_stmt_expr;
6741
6742   /* Scope of outermost declarations of identifiers with variably
6743      modified type within this switch statement; if nonzero, case and
6744      default labels may not appear.  */
6745   unsigned int blocked_vm;
6746
6747   /* The next node on the stack.  */
6748   struct c_switch *next;
6749 };
6750
6751 /* A stack of the currently active switch statements.  The innermost
6752    switch statement is on the top of the stack.  There is no need to
6753    mark the stack for garbage collection because it is only active
6754    during the processing of the body of a function, and we never
6755    collect at that point.  */
6756
6757 struct c_switch *c_switch_stack;
6758
6759 /* Start a C switch statement, testing expression EXP.  Return the new
6760    SWITCH_EXPR.  */
6761
6762 tree
6763 c_start_case (tree exp)
6764 {
6765   enum tree_code code;
6766   tree type, orig_type = error_mark_node;
6767   struct c_switch *cs;
6768
6769   if (exp != error_mark_node)
6770     {
6771       code = TREE_CODE (TREE_TYPE (exp));
6772       orig_type = TREE_TYPE (exp);
6773
6774       if (!INTEGRAL_TYPE_P (orig_type)
6775           && code != ERROR_MARK)
6776         {
6777           error ("switch quantity not an integer");
6778           exp = integer_zero_node;
6779           orig_type = error_mark_node;
6780         }
6781       else
6782         {
6783           type = TYPE_MAIN_VARIANT (TREE_TYPE (exp));
6784
6785           if (!in_system_header
6786               && (type == long_integer_type_node
6787                   || type == long_unsigned_type_node))
6788             warning (OPT_Wtraditional, "%<long%> switch expression not "
6789                      "converted to %<int%> in ISO C");
6790
6791           exp = default_conversion (exp);
6792           type = TREE_TYPE (exp);
6793         }
6794     }
6795
6796   /* Add this new SWITCH_EXPR to the stack.  */
6797   cs = XNEW (struct c_switch);
6798   cs->switch_expr = build3 (SWITCH_EXPR, orig_type, exp, NULL_TREE, NULL_TREE);
6799   cs->orig_type = orig_type;
6800   cs->cases = splay_tree_new (case_compare, NULL, NULL);
6801   cs->blocked_stmt_expr = 0;
6802   cs->blocked_vm = 0;
6803   cs->next = c_switch_stack;
6804   c_switch_stack = cs;
6805
6806   return add_stmt (cs->switch_expr);
6807 }
6808
6809 /* Process a case label.  */
6810
6811 tree
6812 do_case (tree low_value, tree high_value)
6813 {
6814   tree label = NULL_TREE;
6815
6816   if (c_switch_stack && !c_switch_stack->blocked_stmt_expr
6817       && !c_switch_stack->blocked_vm)
6818     {
6819       label = c_add_case_label (c_switch_stack->cases,
6820                                 SWITCH_COND (c_switch_stack->switch_expr),
6821                                 c_switch_stack->orig_type,
6822                                 low_value, high_value);
6823       if (label == error_mark_node)
6824         label = NULL_TREE;
6825     }
6826   else if (c_switch_stack && c_switch_stack->blocked_stmt_expr)
6827     {
6828       if (low_value)
6829         error ("case label in statement expression not containing "
6830                "enclosing switch statement");
6831       else
6832         error ("%<default%> label in statement expression not containing "
6833                "enclosing switch statement");
6834     }
6835   else if (c_switch_stack && c_switch_stack->blocked_vm)
6836     {
6837       if (low_value)
6838         error ("case label in scope of identifier with variably modified "
6839                "type not containing enclosing switch statement");
6840       else
6841         error ("%<default%> label in scope of identifier with variably "
6842                "modified type not containing enclosing switch statement");
6843     }
6844   else if (low_value)
6845     error ("case label not within a switch statement");
6846   else
6847     error ("%<default%> label not within a switch statement");
6848
6849   return label;
6850 }
6851
6852 /* Finish the switch statement.  */
6853
6854 void
6855 c_finish_case (tree body)
6856 {
6857   struct c_switch *cs = c_switch_stack;
6858   location_t switch_location;
6859
6860   SWITCH_BODY (cs->switch_expr) = body;
6861
6862   /* We must not be within a statement expression nested in the switch
6863      at this point; we might, however, be within the scope of an
6864      identifier with variably modified type nested in the switch.  */
6865   gcc_assert (!cs->blocked_stmt_expr);
6866
6867   /* Emit warnings as needed.  */
6868   if (EXPR_HAS_LOCATION (cs->switch_expr))
6869     switch_location = EXPR_LOCATION (cs->switch_expr);
6870   else
6871     switch_location = input_location;
6872   c_do_switch_warnings (cs->cases, switch_location,
6873                         TREE_TYPE (cs->switch_expr),
6874                         SWITCH_COND (cs->switch_expr));
6875
6876   /* Pop the stack.  */
6877   c_switch_stack = cs->next;
6878   splay_tree_delete (cs->cases);
6879   XDELETE (cs);
6880 }
6881 \f
6882 /* Emit an if statement.  IF_LOCUS is the location of the 'if'.  COND,
6883    THEN_BLOCK and ELSE_BLOCK are expressions to be used; ELSE_BLOCK
6884    may be null.  NESTED_IF is true if THEN_BLOCK contains another IF
6885    statement, and was not surrounded with parenthesis.  */
6886
6887 void
6888 c_finish_if_stmt (location_t if_locus, tree cond, tree then_block,
6889                   tree else_block, bool nested_if)
6890 {
6891   tree stmt;
6892
6893   /* Diagnose an ambiguous else if if-then-else is nested inside if-then.  */
6894   if (warn_parentheses && nested_if && else_block == NULL)
6895     {
6896       tree inner_if = then_block;
6897
6898       /* We know from the grammar productions that there is an IF nested
6899          within THEN_BLOCK.  Due to labels and c99 conditional declarations,
6900          it might not be exactly THEN_BLOCK, but should be the last
6901          non-container statement within.  */
6902       while (1)
6903         switch (TREE_CODE (inner_if))
6904           {
6905           case COND_EXPR:
6906             goto found;
6907           case BIND_EXPR:
6908             inner_if = BIND_EXPR_BODY (inner_if);
6909             break;
6910           case STATEMENT_LIST:
6911             inner_if = expr_last (then_block);
6912             break;
6913           case TRY_FINALLY_EXPR:
6914           case TRY_CATCH_EXPR:
6915             inner_if = TREE_OPERAND (inner_if, 0);
6916             break;
6917           default:
6918             gcc_unreachable ();
6919           }
6920     found:
6921
6922       if (COND_EXPR_ELSE (inner_if))
6923          warning (0, "%Hsuggest explicit braces to avoid ambiguous %<else%>",
6924                   &if_locus);
6925     }
6926
6927   /* Diagnose ";" via the special empty statement node that we create.  */
6928   if (extra_warnings)
6929     {
6930       if (TREE_CODE (then_block) == NOP_EXPR && !TREE_TYPE (then_block))
6931         {
6932           if (!else_block)
6933             warning (0, "%Hempty body in an if-statement",
6934                      EXPR_LOCUS (then_block));
6935           then_block = alloc_stmt_list ();
6936         }
6937       if (else_block
6938           && TREE_CODE (else_block) == NOP_EXPR
6939           && !TREE_TYPE (else_block))
6940         {
6941           warning (0, "%Hempty body in an else-statement",
6942                    EXPR_LOCUS (else_block));
6943           else_block = alloc_stmt_list ();
6944         }
6945     }
6946
6947   stmt = build3 (COND_EXPR, void_type_node, cond, then_block, else_block);
6948   SET_EXPR_LOCATION (stmt, if_locus);
6949   add_stmt (stmt);
6950 }
6951
6952 /* Emit a general-purpose loop construct.  START_LOCUS is the location of
6953    the beginning of the loop.  COND is the loop condition.  COND_IS_FIRST
6954    is false for DO loops.  INCR is the FOR increment expression.  BODY is
6955    the statement controlled by the loop.  BLAB is the break label.  CLAB is
6956    the continue label.  Everything is allowed to be NULL.  */
6957
6958 void
6959 c_finish_loop (location_t start_locus, tree cond, tree incr, tree body,
6960                tree blab, tree clab, bool cond_is_first)
6961 {
6962   tree entry = NULL, exit = NULL, t;
6963
6964   /* If the condition is zero don't generate a loop construct.  */
6965   if (cond && integer_zerop (cond))
6966     {
6967       if (cond_is_first)
6968         {
6969           t = build_and_jump (&blab);
6970           SET_EXPR_LOCATION (t, start_locus);
6971           add_stmt (t);
6972         }
6973     }
6974   else
6975     {
6976       tree top = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
6977
6978       /* If we have an exit condition, then we build an IF with gotos either
6979          out of the loop, or to the top of it.  If there's no exit condition,
6980          then we just build a jump back to the top.  */
6981       exit = build_and_jump (&LABEL_EXPR_LABEL (top));
6982
6983       if (cond && !integer_nonzerop (cond))
6984         {
6985           /* Canonicalize the loop condition to the end.  This means
6986              generating a branch to the loop condition.  Reuse the
6987              continue label, if possible.  */
6988           if (cond_is_first)
6989             {
6990               if (incr || !clab)
6991                 {
6992                   entry = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
6993                   t = build_and_jump (&LABEL_EXPR_LABEL (entry));
6994                 }
6995               else
6996                 t = build1 (GOTO_EXPR, void_type_node, clab);
6997               SET_EXPR_LOCATION (t, start_locus);
6998               add_stmt (t);
6999             }
7000
7001           t = build_and_jump (&blab);
7002           exit = build3 (COND_EXPR, void_type_node, cond, exit, t);
7003           exit = fold (exit);
7004           if (cond_is_first)
7005             SET_EXPR_LOCATION (exit, start_locus);
7006           else
7007             SET_EXPR_LOCATION (exit, input_location);
7008         }
7009
7010       add_stmt (top);
7011     }
7012
7013   if (body)
7014     add_stmt (body);
7015   if (clab)
7016     add_stmt (build1 (LABEL_EXPR, void_type_node, clab));
7017   if (incr)
7018     add_stmt (incr);
7019   if (entry)
7020     add_stmt (entry);
7021   if (exit)
7022     add_stmt (exit);
7023   if (blab)
7024     add_stmt (build1 (LABEL_EXPR, void_type_node, blab));
7025 }
7026
7027 tree
7028 c_finish_bc_stmt (tree *label_p, bool is_break)
7029 {
7030   bool skip;
7031   tree label = *label_p;
7032
7033   /* In switch statements break is sometimes stylistically used after
7034      a return statement.  This can lead to spurious warnings about
7035      control reaching the end of a non-void function when it is
7036      inlined.  Note that we are calling block_may_fallthru with
7037      language specific tree nodes; this works because
7038      block_may_fallthru returns true when given something it does not
7039      understand.  */
7040   skip = !block_may_fallthru (cur_stmt_list);
7041
7042   if (!label)
7043     {
7044       if (!skip)
7045         *label_p = label = create_artificial_label ();
7046     }
7047   else if (TREE_CODE (label) != LABEL_DECL)
7048     {
7049       if (is_break)
7050         error ("break statement not within loop or switch");
7051       else
7052         error ("continue statement not within a loop");
7053       return NULL_TREE;
7054     }
7055
7056   if (skip)
7057     return NULL_TREE;
7058
7059   return add_stmt (build1 (GOTO_EXPR, void_type_node, label));
7060 }
7061
7062 /* A helper routine for c_process_expr_stmt and c_finish_stmt_expr.  */
7063
7064 static void
7065 emit_side_effect_warnings (tree expr)
7066 {
7067   if (expr == error_mark_node)
7068     ;
7069   else if (!TREE_SIDE_EFFECTS (expr))
7070     {
7071       if (!VOID_TYPE_P (TREE_TYPE (expr)) && !TREE_NO_WARNING (expr))
7072         warning (0, "%Hstatement with no effect",
7073                  EXPR_HAS_LOCATION (expr) ? EXPR_LOCUS (expr) : &input_location);
7074     }
7075   else if (warn_unused_value)
7076     warn_if_unused_value (expr, input_location);
7077 }
7078
7079 /* Process an expression as if it were a complete statement.  Emit
7080    diagnostics, but do not call ADD_STMT.  */
7081
7082 tree
7083 c_process_expr_stmt (tree expr)
7084 {
7085   if (!expr)
7086     return NULL_TREE;
7087
7088   if (warn_sequence_point)
7089     verify_sequence_points (expr);
7090
7091   if (TREE_TYPE (expr) != error_mark_node
7092       && !COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (expr))
7093       && TREE_CODE (TREE_TYPE (expr)) != ARRAY_TYPE)
7094     error ("expression statement has incomplete type");
7095
7096   /* If we're not processing a statement expression, warn about unused values.
7097      Warnings for statement expressions will be emitted later, once we figure
7098      out which is the result.  */
7099   if (!STATEMENT_LIST_STMT_EXPR (cur_stmt_list)
7100       && (extra_warnings || warn_unused_value))
7101     emit_side_effect_warnings (expr);
7102
7103   /* If the expression is not of a type to which we cannot assign a line
7104      number, wrap the thing in a no-op NOP_EXPR.  */
7105   if (DECL_P (expr) || CONSTANT_CLASS_P (expr))
7106     expr = build1 (NOP_EXPR, TREE_TYPE (expr), expr);
7107
7108   if (EXPR_P (expr))
7109     SET_EXPR_LOCATION (expr, input_location);
7110
7111   return expr;
7112 }
7113
7114 /* Emit an expression as a statement.  */
7115
7116 tree
7117 c_finish_expr_stmt (tree expr)
7118 {
7119   if (expr)
7120     return add_stmt (c_process_expr_stmt (expr));
7121   else
7122     return NULL;
7123 }
7124
7125 /* Do the opposite and emit a statement as an expression.  To begin,
7126    create a new binding level and return it.  */
7127
7128 tree
7129 c_begin_stmt_expr (void)
7130 {
7131   tree ret;
7132   struct c_label_context_se *nstack;
7133   struct c_label_list *glist;
7134
7135   /* We must force a BLOCK for this level so that, if it is not expanded
7136      later, there is a way to turn off the entire subtree of blocks that
7137      are contained in it.  */
7138   keep_next_level ();
7139   ret = c_begin_compound_stmt (true);
7140   if (c_switch_stack)
7141     {
7142       c_switch_stack->blocked_stmt_expr++;
7143       gcc_assert (c_switch_stack->blocked_stmt_expr != 0);
7144     }
7145   for (glist = label_context_stack_se->labels_used;
7146        glist != NULL;
7147        glist = glist->next)
7148     {
7149       C_DECL_UNDEFINABLE_STMT_EXPR (glist->label) = 1;
7150     }
7151   nstack = XOBNEW (&parser_obstack, struct c_label_context_se);
7152   nstack->labels_def = NULL;
7153   nstack->labels_used = NULL;
7154   nstack->next = label_context_stack_se;
7155   label_context_stack_se = nstack;
7156
7157   /* Mark the current statement list as belonging to a statement list.  */
7158   STATEMENT_LIST_STMT_EXPR (ret) = 1;
7159
7160   return ret;
7161 }
7162
7163 tree
7164 c_finish_stmt_expr (tree body)
7165 {
7166   tree last, type, tmp, val;
7167   tree *last_p;
7168   struct c_label_list *dlist, *glist, *glist_prev = NULL;
7169
7170   body = c_end_compound_stmt (body, true);
7171   if (c_switch_stack)
7172     {
7173       gcc_assert (c_switch_stack->blocked_stmt_expr != 0);
7174       c_switch_stack->blocked_stmt_expr--;
7175     }
7176   /* It is no longer possible to jump to labels defined within this
7177      statement expression.  */
7178   for (dlist = label_context_stack_se->labels_def;
7179        dlist != NULL;
7180        dlist = dlist->next)
7181     {
7182       C_DECL_UNJUMPABLE_STMT_EXPR (dlist->label) = 1;
7183     }
7184   /* It is again possible to define labels with a goto just outside
7185      this statement expression.  */
7186   for (glist = label_context_stack_se->next->labels_used;
7187        glist != NULL;
7188        glist = glist->next)
7189     {
7190       C_DECL_UNDEFINABLE_STMT_EXPR (glist->label) = 0;
7191       glist_prev = glist;
7192     }
7193   if (glist_prev != NULL)
7194     glist_prev->next = label_context_stack_se->labels_used;
7195   else
7196     label_context_stack_se->next->labels_used
7197       = label_context_stack_se->labels_used;
7198   label_context_stack_se = label_context_stack_se->next;
7199
7200   /* Locate the last statement in BODY.  See c_end_compound_stmt
7201      about always returning a BIND_EXPR.  */
7202   last_p = &BIND_EXPR_BODY (body);
7203   last = BIND_EXPR_BODY (body);
7204
7205  continue_searching:
7206   if (TREE_CODE (last) == STATEMENT_LIST)
7207     {
7208       tree_stmt_iterator i;
7209
7210       /* This can happen with degenerate cases like ({ }).  No value.  */
7211       if (!TREE_SIDE_EFFECTS (last))
7212         return body;
7213
7214       /* If we're supposed to generate side effects warnings, process
7215          all of the statements except the last.  */
7216       if (extra_warnings || warn_unused_value)
7217         {
7218           for (i = tsi_start (last); !tsi_one_before_end_p (i); tsi_next (&i))
7219             emit_side_effect_warnings (tsi_stmt (i));
7220         }
7221       else
7222         i = tsi_last (last);
7223       last_p = tsi_stmt_ptr (i);
7224       last = *last_p;
7225     }
7226
7227   /* If the end of the list is exception related, then the list was split
7228      by a call to push_cleanup.  Continue searching.  */
7229   if (TREE_CODE (last) == TRY_FINALLY_EXPR
7230       || TREE_CODE (last) == TRY_CATCH_EXPR)
7231     {
7232       last_p = &TREE_OPERAND (last, 0);
7233       last = *last_p;
7234       goto continue_searching;
7235     }
7236
7237   /* In the case that the BIND_EXPR is not necessary, return the
7238      expression out from inside it.  */
7239   if (last == error_mark_node
7240       || (last == BIND_EXPR_BODY (body)
7241           && BIND_EXPR_VARS (body) == NULL))
7242     return last;
7243
7244   /* Extract the type of said expression.  */
7245   type = TREE_TYPE (last);
7246
7247   /* If we're not returning a value at all, then the BIND_EXPR that
7248      we already have is a fine expression to return.  */
7249   if (!type || VOID_TYPE_P (type))
7250     return body;
7251
7252   /* Now that we've located the expression containing the value, it seems
7253      silly to make voidify_wrapper_expr repeat the process.  Create a
7254      temporary of the appropriate type and stick it in a TARGET_EXPR.  */
7255   tmp = create_tmp_var_raw (type, NULL);
7256
7257   /* Unwrap a no-op NOP_EXPR as added by c_finish_expr_stmt.  This avoids
7258      tree_expr_nonnegative_p giving up immediately.  */
7259   val = last;
7260   if (TREE_CODE (val) == NOP_EXPR
7261       && TREE_TYPE (val) == TREE_TYPE (TREE_OPERAND (val, 0)))
7262     val = TREE_OPERAND (val, 0);
7263
7264   *last_p = build2 (MODIFY_EXPR, void_type_node, tmp, val);
7265   SET_EXPR_LOCUS (*last_p, EXPR_LOCUS (last));
7266
7267   return build4 (TARGET_EXPR, type, tmp, body, NULL_TREE, NULL_TREE);
7268 }
7269
7270 /* Begin the scope of an identifier of variably modified type, scope
7271    number SCOPE.  Jumping from outside this scope to inside it is not
7272    permitted.  */
7273
7274 void
7275 c_begin_vm_scope (unsigned int scope)
7276 {
7277   struct c_label_context_vm *nstack;
7278   struct c_label_list *glist;
7279
7280   gcc_assert (scope > 0);
7281   if (c_switch_stack && !c_switch_stack->blocked_vm)
7282     c_switch_stack->blocked_vm = scope;
7283   for (glist = label_context_stack_vm->labels_used;
7284        glist != NULL;
7285        glist = glist->next)
7286     {
7287       C_DECL_UNDEFINABLE_VM (glist->label) = 1;
7288     }
7289   nstack = XOBNEW (&parser_obstack, struct c_label_context_vm);
7290   nstack->labels_def = NULL;
7291   nstack->labels_used = NULL;
7292   nstack->scope = scope;
7293   nstack->next = label_context_stack_vm;
7294   label_context_stack_vm = nstack;
7295 }
7296
7297 /* End a scope which may contain identifiers of variably modified
7298    type, scope number SCOPE.  */
7299
7300 void
7301 c_end_vm_scope (unsigned int scope)
7302 {
7303   if (label_context_stack_vm == NULL)
7304     return;
7305   if (c_switch_stack && c_switch_stack->blocked_vm == scope)
7306     c_switch_stack->blocked_vm = 0;
7307   /* We may have a number of nested scopes of identifiers with
7308      variably modified type, all at this depth.  Pop each in turn.  */
7309   while (label_context_stack_vm->scope == scope)
7310     {
7311       struct c_label_list *dlist, *glist, *glist_prev = NULL;
7312
7313       /* It is no longer possible to jump to labels defined within this
7314          scope.  */
7315       for (dlist = label_context_stack_vm->labels_def;
7316            dlist != NULL;
7317            dlist = dlist->next)
7318         {
7319           C_DECL_UNJUMPABLE_VM (dlist->label) = 1;
7320         }
7321       /* It is again possible to define labels with a goto just outside
7322          this scope.  */
7323       for (glist = label_context_stack_vm->next->labels_used;
7324            glist != NULL;
7325            glist = glist->next)
7326         {
7327           C_DECL_UNDEFINABLE_VM (glist->label) = 0;
7328           glist_prev = glist;
7329         }
7330       if (glist_prev != NULL)
7331         glist_prev->next = label_context_stack_vm->labels_used;
7332       else
7333         label_context_stack_vm->next->labels_used
7334           = label_context_stack_vm->labels_used;
7335       label_context_stack_vm = label_context_stack_vm->next;
7336     }
7337 }
7338 \f
7339 /* Begin and end compound statements.  This is as simple as pushing
7340    and popping new statement lists from the tree.  */
7341
7342 tree
7343 c_begin_compound_stmt (bool do_scope)
7344 {
7345   tree stmt = push_stmt_list ();
7346   if (do_scope)
7347     push_scope ();
7348   return stmt;
7349 }
7350
7351 tree
7352 c_end_compound_stmt (tree stmt, bool do_scope)
7353 {
7354   tree block = NULL;
7355
7356   if (do_scope)
7357     {
7358       if (c_dialect_objc ())
7359         objc_clear_super_receiver ();
7360       block = pop_scope ();
7361     }
7362
7363   stmt = pop_stmt_list (stmt);
7364   stmt = c_build_bind_expr (block, stmt);
7365
7366   /* If this compound statement is nested immediately inside a statement
7367      expression, then force a BIND_EXPR to be created.  Otherwise we'll
7368      do the wrong thing for ({ { 1; } }) or ({ 1; { } }).  In particular,
7369      STATEMENT_LISTs merge, and thus we can lose track of what statement
7370      was really last.  */
7371   if (cur_stmt_list
7372       && STATEMENT_LIST_STMT_EXPR (cur_stmt_list)
7373       && TREE_CODE (stmt) != BIND_EXPR)
7374     {
7375       stmt = build3 (BIND_EXPR, void_type_node, NULL, stmt, NULL);
7376       TREE_SIDE_EFFECTS (stmt) = 1;
7377     }
7378
7379   return stmt;
7380 }
7381
7382 /* Queue a cleanup.  CLEANUP is an expression/statement to be executed
7383    when the current scope is exited.  EH_ONLY is true when this is not
7384    meant to apply to normal control flow transfer.  */
7385
7386 void
7387 push_cleanup (tree ARG_UNUSED (decl), tree cleanup, bool eh_only)
7388 {
7389   enum tree_code code;
7390   tree stmt, list;
7391   bool stmt_expr;
7392
7393   code = eh_only ? TRY_CATCH_EXPR : TRY_FINALLY_EXPR;
7394   stmt = build_stmt (code, NULL, cleanup);
7395   add_stmt (stmt);
7396   stmt_expr = STATEMENT_LIST_STMT_EXPR (cur_stmt_list);
7397   list = push_stmt_list ();
7398   TREE_OPERAND (stmt, 0) = list;
7399   STATEMENT_LIST_STMT_EXPR (list) = stmt_expr;
7400 }
7401 \f
7402 /* Build a binary-operation expression without default conversions.
7403    CODE is the kind of expression to build.
7404    This function differs from `build' in several ways:
7405    the data type of the result is computed and recorded in it,
7406    warnings are generated if arg data types are invalid,
7407    special handling for addition and subtraction of pointers is known,
7408    and some optimization is done (operations on narrow ints
7409    are done in the narrower type when that gives the same result).
7410    Constant folding is also done before the result is returned.
7411
7412    Note that the operands will never have enumeral types, or function
7413    or array types, because either they will have the default conversions
7414    performed or they have both just been converted to some other type in which
7415    the arithmetic is to be done.  */
7416
7417 tree
7418 build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
7419                  int convert_p)
7420 {
7421   tree type0, type1;
7422   enum tree_code code0, code1;
7423   tree op0, op1;
7424   const char *invalid_op_diag;
7425
7426   /* Expression code to give to the expression when it is built.
7427      Normally this is CODE, which is what the caller asked for,
7428      but in some special cases we change it.  */
7429   enum tree_code resultcode = code;
7430
7431   /* Data type in which the computation is to be performed.
7432      In the simplest cases this is the common type of the arguments.  */
7433   tree result_type = NULL;
7434
7435   /* Nonzero means operands have already been type-converted
7436      in whatever way is necessary.
7437      Zero means they need to be converted to RESULT_TYPE.  */
7438   int converted = 0;
7439
7440   /* Nonzero means create the expression with this type, rather than
7441      RESULT_TYPE.  */
7442   tree build_type = 0;
7443
7444   /* Nonzero means after finally constructing the expression
7445      convert it to this type.  */
7446   tree final_type = 0;
7447
7448   /* Nonzero if this is an operation like MIN or MAX which can
7449      safely be computed in short if both args are promoted shorts.
7450      Also implies COMMON.
7451      -1 indicates a bitwise operation; this makes a difference
7452      in the exact conditions for when it is safe to do the operation
7453      in a narrower mode.  */
7454   int shorten = 0;
7455
7456   /* Nonzero if this is a comparison operation;
7457      if both args are promoted shorts, compare the original shorts.
7458      Also implies COMMON.  */
7459   int short_compare = 0;
7460
7461   /* Nonzero if this is a right-shift operation, which can be computed on the
7462      original short and then promoted if the operand is a promoted short.  */
7463   int short_shift = 0;
7464
7465   /* Nonzero means set RESULT_TYPE to the common type of the args.  */
7466   int common = 0;
7467
7468   /* True means types are compatible as far as ObjC is concerned.  */
7469   bool objc_ok;
7470
7471   if (convert_p)
7472     {
7473       op0 = default_conversion (orig_op0);
7474       op1 = default_conversion (orig_op1);
7475     }
7476   else
7477     {
7478       op0 = orig_op0;
7479       op1 = orig_op1;
7480     }
7481
7482   type0 = TREE_TYPE (op0);
7483   type1 = TREE_TYPE (op1);
7484
7485   /* The expression codes of the data types of the arguments tell us
7486      whether the arguments are integers, floating, pointers, etc.  */
7487   code0 = TREE_CODE (type0);
7488   code1 = TREE_CODE (type1);
7489
7490   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
7491   STRIP_TYPE_NOPS (op0);
7492   STRIP_TYPE_NOPS (op1);
7493
7494   /* If an error was already reported for one of the arguments,
7495      avoid reporting another error.  */
7496
7497   if (code0 == ERROR_MARK || code1 == ERROR_MARK)
7498     return error_mark_node;
7499
7500   if ((invalid_op_diag
7501        = targetm.invalid_binary_op (code, type0, type1)))
7502     {
7503       error (invalid_op_diag);
7504       return error_mark_node;
7505     }
7506
7507   objc_ok = objc_compare_types (type0, type1, -3, NULL_TREE);
7508
7509   switch (code)
7510     {
7511     case PLUS_EXPR:
7512       /* Handle the pointer + int case.  */
7513       if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7514         return pointer_int_sum (PLUS_EXPR, op0, op1);
7515       else if (code1 == POINTER_TYPE && code0 == INTEGER_TYPE)
7516         return pointer_int_sum (PLUS_EXPR, op1, op0);
7517       else
7518         common = 1;
7519       break;
7520
7521     case MINUS_EXPR:
7522       /* Subtraction of two similar pointers.
7523          We must subtract them as integers, then divide by object size.  */
7524       if (code0 == POINTER_TYPE && code1 == POINTER_TYPE
7525           && comp_target_types (type0, type1))
7526         return pointer_diff (op0, op1);
7527       /* Handle pointer minus int.  Just like pointer plus int.  */
7528       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7529         return pointer_int_sum (MINUS_EXPR, op0, op1);
7530       else
7531         common = 1;
7532       break;
7533
7534     case MULT_EXPR:
7535       common = 1;
7536       break;
7537
7538     case TRUNC_DIV_EXPR:
7539     case CEIL_DIV_EXPR:
7540     case FLOOR_DIV_EXPR:
7541     case ROUND_DIV_EXPR:
7542     case EXACT_DIV_EXPR:
7543       /* Floating point division by zero is a legitimate way to obtain
7544          infinities and NaNs.  */
7545       if (skip_evaluation == 0 && integer_zerop (op1))
7546         warning (OPT_Wdiv_by_zero, "division by zero");
7547
7548       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
7549            || code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
7550           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
7551               || code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE))
7552         {
7553           enum tree_code tcode0 = code0, tcode1 = code1;
7554
7555           if (code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
7556             tcode0 = TREE_CODE (TREE_TYPE (TREE_TYPE (op0)));
7557           if (code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE)
7558             tcode1 = TREE_CODE (TREE_TYPE (TREE_TYPE (op1)));
7559
7560           if (!(tcode0 == INTEGER_TYPE && tcode1 == INTEGER_TYPE))
7561             resultcode = RDIV_EXPR;
7562           else
7563             /* Although it would be tempting to shorten always here, that
7564                loses on some targets, since the modulo instruction is
7565                undefined if the quotient can't be represented in the
7566                computation mode.  We shorten only if unsigned or if
7567                dividing by something we know != -1.  */
7568             shorten = (TYPE_UNSIGNED (TREE_TYPE (orig_op0))
7569                        || (TREE_CODE (op1) == INTEGER_CST
7570                            && !integer_all_onesp (op1)));
7571           common = 1;
7572         }
7573       break;
7574
7575     case BIT_AND_EXPR:
7576     case BIT_IOR_EXPR:
7577     case BIT_XOR_EXPR:
7578       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7579         shorten = -1;
7580       else if (code0 == VECTOR_TYPE && code1 == VECTOR_TYPE)
7581         common = 1;
7582       break;
7583
7584     case TRUNC_MOD_EXPR:
7585     case FLOOR_MOD_EXPR:
7586       if (skip_evaluation == 0 && integer_zerop (op1))
7587         warning (OPT_Wdiv_by_zero, "division by zero");
7588
7589       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7590         {
7591           /* Although it would be tempting to shorten always here, that loses
7592              on some targets, since the modulo instruction is undefined if the
7593              quotient can't be represented in the computation mode.  We shorten
7594              only if unsigned or if dividing by something we know != -1.  */
7595           shorten = (TYPE_UNSIGNED (TREE_TYPE (orig_op0))
7596                      || (TREE_CODE (op1) == INTEGER_CST
7597                          && !integer_all_onesp (op1)));
7598           common = 1;
7599         }
7600       break;
7601
7602     case TRUTH_ANDIF_EXPR:
7603     case TRUTH_ORIF_EXPR:
7604     case TRUTH_AND_EXPR:
7605     case TRUTH_OR_EXPR:
7606     case TRUTH_XOR_EXPR:
7607       if ((code0 == INTEGER_TYPE || code0 == POINTER_TYPE
7608            || code0 == REAL_TYPE || code0 == COMPLEX_TYPE)
7609           && (code1 == INTEGER_TYPE || code1 == POINTER_TYPE
7610               || code1 == REAL_TYPE || code1 == COMPLEX_TYPE))
7611         {
7612           /* Result of these operations is always an int,
7613              but that does not mean the operands should be
7614              converted to ints!  */
7615           result_type = integer_type_node;
7616           op0 = c_common_truthvalue_conversion (op0);
7617           op1 = c_common_truthvalue_conversion (op1);
7618           converted = 1;
7619         }
7620       break;
7621
7622       /* Shift operations: result has same type as first operand;
7623          always convert second operand to int.
7624          Also set SHORT_SHIFT if shifting rightward.  */
7625
7626     case RSHIFT_EXPR:
7627       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7628         {
7629           if (TREE_CODE (op1) == INTEGER_CST && skip_evaluation == 0)
7630             {
7631               if (tree_int_cst_sgn (op1) < 0)
7632                 warning (0, "right shift count is negative");
7633               else
7634                 {
7635                   if (!integer_zerop (op1))
7636                     short_shift = 1;
7637
7638                   if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
7639                     warning (0, "right shift count >= width of type");
7640                 }
7641             }
7642
7643           /* Use the type of the value to be shifted.  */
7644           result_type = type0;
7645           /* Convert the shift-count to an integer, regardless of size
7646              of value being shifted.  */
7647           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
7648             op1 = convert (integer_type_node, op1);
7649           /* Avoid converting op1 to result_type later.  */
7650           converted = 1;
7651         }
7652       break;
7653
7654     case LSHIFT_EXPR:
7655       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7656         {
7657           if (TREE_CODE (op1) == INTEGER_CST && skip_evaluation == 0)
7658             {
7659               if (tree_int_cst_sgn (op1) < 0)
7660                 warning (0, "left shift count is negative");
7661
7662               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
7663                 warning (0, "left shift count >= width of type");
7664             }
7665
7666           /* Use the type of the value to be shifted.  */
7667           result_type = type0;
7668           /* Convert the shift-count to an integer, regardless of size
7669              of value being shifted.  */
7670           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
7671             op1 = convert (integer_type_node, op1);
7672           /* Avoid converting op1 to result_type later.  */
7673           converted = 1;
7674         }
7675       break;
7676
7677     case EQ_EXPR:
7678     case NE_EXPR:
7679       if (code0 == REAL_TYPE || code1 == REAL_TYPE)
7680         warning (OPT_Wfloat_equal,
7681                  "comparing floating point with == or != is unsafe");
7682       /* Result of comparison is always int,
7683          but don't convert the args to int!  */
7684       build_type = integer_type_node;
7685       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
7686            || code0 == COMPLEX_TYPE)
7687           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
7688               || code1 == COMPLEX_TYPE))
7689         short_compare = 1;
7690       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
7691         {
7692           tree tt0 = TREE_TYPE (type0);
7693           tree tt1 = TREE_TYPE (type1);
7694           /* Anything compares with void *.  void * compares with anything.
7695              Otherwise, the targets must be compatible
7696              and both must be object or both incomplete.  */
7697           if (comp_target_types (type0, type1))
7698             result_type = common_pointer_type (type0, type1);
7699           else if (VOID_TYPE_P (tt0))
7700             {
7701               /* op0 != orig_op0 detects the case of something
7702                  whose value is 0 but which isn't a valid null ptr const.  */
7703               if (pedantic && (!integer_zerop (op0) || op0 != orig_op0)
7704                   && TREE_CODE (tt1) == FUNCTION_TYPE)
7705                 pedwarn ("ISO C forbids comparison of %<void *%>"
7706                          " with function pointer");
7707             }
7708           else if (VOID_TYPE_P (tt1))
7709             {
7710               if (pedantic && (!integer_zerop (op1) || op1 != orig_op1)
7711                   && TREE_CODE (tt0) == FUNCTION_TYPE)
7712                 pedwarn ("ISO C forbids comparison of %<void *%>"
7713                          " with function pointer");
7714             }
7715           else
7716             /* Avoid warning about the volatile ObjC EH puts on decls.  */
7717             if (!objc_ok)
7718               pedwarn ("comparison of distinct pointer types lacks a cast");
7719
7720           if (result_type == NULL_TREE)
7721             result_type = ptr_type_node;
7722         }
7723       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
7724                && integer_zerop (op1))
7725         result_type = type0;
7726       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
7727                && integer_zerop (op0))
7728         result_type = type1;
7729       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7730         {
7731           result_type = type0;
7732           pedwarn ("comparison between pointer and integer");
7733         }
7734       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
7735         {
7736           result_type = type1;
7737           pedwarn ("comparison between pointer and integer");
7738         }
7739       break;
7740
7741     case LE_EXPR:
7742     case GE_EXPR:
7743     case LT_EXPR:
7744     case GT_EXPR:
7745       build_type = integer_type_node;
7746       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
7747           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
7748         short_compare = 1;
7749       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
7750         {
7751           if (comp_target_types (type0, type1))
7752             {
7753               result_type = common_pointer_type (type0, type1);
7754               if (!COMPLETE_TYPE_P (TREE_TYPE (type0))
7755                   != !COMPLETE_TYPE_P (TREE_TYPE (type1)))
7756                 pedwarn ("comparison of complete and incomplete pointers");
7757               else if (pedantic
7758                        && TREE_CODE (TREE_TYPE (type0)) == FUNCTION_TYPE)
7759                 pedwarn ("ISO C forbids ordered comparisons of pointers to functions");
7760             }
7761           else
7762             {
7763               result_type = ptr_type_node;
7764               pedwarn ("comparison of distinct pointer types lacks a cast");
7765             }
7766         }
7767       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
7768                && integer_zerop (op1))
7769         {
7770           result_type = type0;
7771           if (pedantic || extra_warnings)
7772             pedwarn ("ordered comparison of pointer with integer zero");
7773         }
7774       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
7775                && integer_zerop (op0))
7776         {
7777           result_type = type1;
7778           if (pedantic)
7779             pedwarn ("ordered comparison of pointer with integer zero");
7780         }
7781       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7782         {
7783           result_type = type0;
7784           pedwarn ("comparison between pointer and integer");
7785         }
7786       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
7787         {
7788           result_type = type1;
7789           pedwarn ("comparison between pointer and integer");
7790         }
7791       break;
7792
7793     default:
7794       gcc_unreachable ();
7795     }
7796
7797   if (code0 == ERROR_MARK || code1 == ERROR_MARK)
7798     return error_mark_node;
7799
7800   if (code0 == VECTOR_TYPE && code1 == VECTOR_TYPE
7801       && (!tree_int_cst_equal (TYPE_SIZE (type0), TYPE_SIZE (type1))
7802           || !same_scalar_type_ignoring_signedness (TREE_TYPE (type0),
7803                                                     TREE_TYPE (type1))))
7804     {
7805       binary_op_error (code);
7806       return error_mark_node;
7807     }
7808
7809   if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE || code0 == COMPLEX_TYPE
7810        || code0 == VECTOR_TYPE)
7811       &&
7812       (code1 == INTEGER_TYPE || code1 == REAL_TYPE || code1 == COMPLEX_TYPE
7813        || code1 == VECTOR_TYPE))
7814     {
7815       int none_complex = (code0 != COMPLEX_TYPE && code1 != COMPLEX_TYPE);
7816
7817       if (shorten || common || short_compare)
7818         result_type = c_common_type (type0, type1);
7819
7820       /* For certain operations (which identify themselves by shorten != 0)
7821          if both args were extended from the same smaller type,
7822          do the arithmetic in that type and then extend.
7823
7824          shorten !=0 and !=1 indicates a bitwise operation.
7825          For them, this optimization is safe only if
7826          both args are zero-extended or both are sign-extended.
7827          Otherwise, we might change the result.
7828          Eg, (short)-1 | (unsigned short)-1 is (int)-1
7829          but calculated in (unsigned short) it would be (unsigned short)-1.  */
7830
7831       if (shorten && none_complex)
7832         {
7833           int unsigned0, unsigned1;
7834           tree arg0 = get_narrower (op0, &unsigned0);
7835           tree arg1 = get_narrower (op1, &unsigned1);
7836           /* UNS is 1 if the operation to be done is an unsigned one.  */
7837           int uns = TYPE_UNSIGNED (result_type);
7838           tree type;
7839
7840           final_type = result_type;
7841
7842           /* Handle the case that OP0 (or OP1) does not *contain* a conversion
7843              but it *requires* conversion to FINAL_TYPE.  */
7844
7845           if ((TYPE_PRECISION (TREE_TYPE (op0))
7846                == TYPE_PRECISION (TREE_TYPE (arg0)))
7847               && TREE_TYPE (op0) != final_type)
7848             unsigned0 = TYPE_UNSIGNED (TREE_TYPE (op0));
7849           if ((TYPE_PRECISION (TREE_TYPE (op1))
7850                == TYPE_PRECISION (TREE_TYPE (arg1)))
7851               && TREE_TYPE (op1) != final_type)
7852             unsigned1 = TYPE_UNSIGNED (TREE_TYPE (op1));
7853
7854           /* Now UNSIGNED0 is 1 if ARG0 zero-extends to FINAL_TYPE.  */
7855
7856           /* For bitwise operations, signedness of nominal type
7857              does not matter.  Consider only how operands were extended.  */
7858           if (shorten == -1)
7859             uns = unsigned0;
7860
7861           /* Note that in all three cases below we refrain from optimizing
7862              an unsigned operation on sign-extended args.
7863              That would not be valid.  */
7864
7865           /* Both args variable: if both extended in same way
7866              from same width, do it in that width.
7867              Do it unsigned if args were zero-extended.  */
7868           if ((TYPE_PRECISION (TREE_TYPE (arg0))
7869                < TYPE_PRECISION (result_type))
7870               && (TYPE_PRECISION (TREE_TYPE (arg1))
7871                   == TYPE_PRECISION (TREE_TYPE (arg0)))
7872               && unsigned0 == unsigned1
7873               && (unsigned0 || !uns))
7874             result_type
7875               = c_common_signed_or_unsigned_type
7876               (unsigned0, c_common_type (TREE_TYPE (arg0), TREE_TYPE (arg1)));
7877           else if (TREE_CODE (arg0) == INTEGER_CST
7878                    && (unsigned1 || !uns)
7879                    && (TYPE_PRECISION (TREE_TYPE (arg1))
7880                        < TYPE_PRECISION (result_type))
7881                    && (type
7882                        = c_common_signed_or_unsigned_type (unsigned1,
7883                                                            TREE_TYPE (arg1)),
7884                        int_fits_type_p (arg0, type)))
7885             result_type = type;
7886           else if (TREE_CODE (arg1) == INTEGER_CST
7887                    && (unsigned0 || !uns)
7888                    && (TYPE_PRECISION (TREE_TYPE (arg0))
7889                        < TYPE_PRECISION (result_type))
7890                    && (type
7891                        = c_common_signed_or_unsigned_type (unsigned0,
7892                                                            TREE_TYPE (arg0)),
7893                        int_fits_type_p (arg1, type)))
7894             result_type = type;
7895         }
7896
7897       /* Shifts can be shortened if shifting right.  */
7898
7899       if (short_shift)
7900         {
7901           int unsigned_arg;
7902           tree arg0 = get_narrower (op0, &unsigned_arg);
7903
7904           final_type = result_type;
7905
7906           if (arg0 == op0 && final_type == TREE_TYPE (op0))
7907             unsigned_arg = TYPE_UNSIGNED (TREE_TYPE (op0));
7908
7909           if (TYPE_PRECISION (TREE_TYPE (arg0)) < TYPE_PRECISION (result_type)
7910               /* We can shorten only if the shift count is less than the
7911                  number of bits in the smaller type size.  */
7912               && compare_tree_int (op1, TYPE_PRECISION (TREE_TYPE (arg0))) < 0
7913               /* We cannot drop an unsigned shift after sign-extension.  */
7914               && (!TYPE_UNSIGNED (final_type) || unsigned_arg))
7915             {
7916               /* Do an unsigned shift if the operand was zero-extended.  */
7917               result_type
7918                 = c_common_signed_or_unsigned_type (unsigned_arg,
7919                                                     TREE_TYPE (arg0));
7920               /* Convert value-to-be-shifted to that type.  */
7921               if (TREE_TYPE (op0) != result_type)
7922                 op0 = convert (result_type, op0);
7923               converted = 1;
7924             }
7925         }
7926
7927       /* Comparison operations are shortened too but differently.
7928          They identify themselves by setting short_compare = 1.  */
7929
7930       if (short_compare)
7931         {
7932           /* Don't write &op0, etc., because that would prevent op0
7933              from being kept in a register.
7934              Instead, make copies of the our local variables and
7935              pass the copies by reference, then copy them back afterward.  */
7936           tree xop0 = op0, xop1 = op1, xresult_type = result_type;
7937           enum tree_code xresultcode = resultcode;
7938           tree val
7939             = shorten_compare (&xop0, &xop1, &xresult_type, &xresultcode);
7940
7941           if (val != 0)
7942             return val;
7943
7944           op0 = xop0, op1 = xop1;
7945           converted = 1;
7946           resultcode = xresultcode;
7947
7948           if (warn_sign_compare && skip_evaluation == 0)
7949             {
7950               int op0_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op0));
7951               int op1_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op1));
7952               int unsignedp0, unsignedp1;
7953               tree primop0 = get_narrower (op0, &unsignedp0);
7954               tree primop1 = get_narrower (op1, &unsignedp1);
7955
7956               xop0 = orig_op0;
7957               xop1 = orig_op1;
7958               STRIP_TYPE_NOPS (xop0);
7959               STRIP_TYPE_NOPS (xop1);
7960
7961               /* Give warnings for comparisons between signed and unsigned
7962                  quantities that may fail.
7963
7964                  Do the checking based on the original operand trees, so that
7965                  casts will be considered, but default promotions won't be.
7966
7967                  Do not warn if the comparison is being done in a signed type,
7968                  since the signed type will only be chosen if it can represent
7969                  all the values of the unsigned type.  */
7970               if (!TYPE_UNSIGNED (result_type))
7971                 /* OK */;
7972               /* Do not warn if both operands are the same signedness.  */
7973               else if (op0_signed == op1_signed)
7974                 /* OK */;
7975               else
7976                 {
7977                   tree sop, uop;
7978
7979                   if (op0_signed)
7980                     sop = xop0, uop = xop1;
7981                   else
7982                     sop = xop1, uop = xop0;
7983
7984                   /* Do not warn if the signed quantity is an
7985                      unsuffixed integer literal (or some static
7986                      constant expression involving such literals or a
7987                      conditional expression involving such literals)
7988                      and it is non-negative.  */
7989                   if (tree_expr_nonnegative_p (sop))
7990                     /* OK */;
7991                   /* Do not warn if the comparison is an equality operation,
7992                      the unsigned quantity is an integral constant, and it
7993                      would fit in the result if the result were signed.  */
7994                   else if (TREE_CODE (uop) == INTEGER_CST
7995                            && (resultcode == EQ_EXPR || resultcode == NE_EXPR)
7996                            && int_fits_type_p
7997                            (uop, c_common_signed_type (result_type)))
7998                     /* OK */;
7999                   /* Do not warn if the unsigned quantity is an enumeration
8000                      constant and its maximum value would fit in the result
8001                      if the result were signed.  */
8002                   else if (TREE_CODE (uop) == INTEGER_CST
8003                            && TREE_CODE (TREE_TYPE (uop)) == ENUMERAL_TYPE
8004                            && int_fits_type_p
8005                            (TYPE_MAX_VALUE (TREE_TYPE (uop)),
8006                             c_common_signed_type (result_type)))
8007                     /* OK */;
8008                   else
8009                     warning (0, "comparison between signed and unsigned");
8010                 }
8011
8012               /* Warn if two unsigned values are being compared in a size
8013                  larger than their original size, and one (and only one) is the
8014                  result of a `~' operator.  This comparison will always fail.
8015
8016                  Also warn if one operand is a constant, and the constant
8017                  does not have all bits set that are set in the ~ operand
8018                  when it is extended.  */
8019
8020               if ((TREE_CODE (primop0) == BIT_NOT_EXPR)
8021                   != (TREE_CODE (primop1) == BIT_NOT_EXPR))
8022                 {
8023                   if (TREE_CODE (primop0) == BIT_NOT_EXPR)
8024                     primop0 = get_narrower (TREE_OPERAND (primop0, 0),
8025                                             &unsignedp0);
8026                   else
8027                     primop1 = get_narrower (TREE_OPERAND (primop1, 0),
8028                                             &unsignedp1);
8029
8030                   if (host_integerp (primop0, 0) || host_integerp (primop1, 0))
8031                     {
8032                       tree primop;
8033                       HOST_WIDE_INT constant, mask;
8034                       int unsignedp, bits;
8035
8036                       if (host_integerp (primop0, 0))
8037                         {
8038                           primop = primop1;
8039                           unsignedp = unsignedp1;
8040                           constant = tree_low_cst (primop0, 0);
8041                         }
8042                       else
8043                         {
8044                           primop = primop0;
8045                           unsignedp = unsignedp0;
8046                           constant = tree_low_cst (primop1, 0);
8047                         }
8048
8049                       bits = TYPE_PRECISION (TREE_TYPE (primop));
8050                       if (bits < TYPE_PRECISION (result_type)
8051                           && bits < HOST_BITS_PER_WIDE_INT && unsignedp)
8052                         {
8053                           mask = (~(HOST_WIDE_INT) 0) << bits;
8054                           if ((mask & constant) != mask)
8055                             warning (0, "comparison of promoted ~unsigned with constant");
8056                         }
8057                     }
8058                   else if (unsignedp0 && unsignedp1
8059                            && (TYPE_PRECISION (TREE_TYPE (primop0))
8060                                < TYPE_PRECISION (result_type))
8061                            && (TYPE_PRECISION (TREE_TYPE (primop1))
8062                                < TYPE_PRECISION (result_type)))
8063                     warning (0, "comparison of promoted ~unsigned with unsigned");
8064                 }
8065             }
8066         }
8067     }
8068
8069   /* At this point, RESULT_TYPE must be nonzero to avoid an error message.
8070      If CONVERTED is zero, both args will be converted to type RESULT_TYPE.
8071      Then the expression will be built.
8072      It will be given type FINAL_TYPE if that is nonzero;
8073      otherwise, it will be given type RESULT_TYPE.  */
8074
8075   if (!result_type)
8076     {
8077       binary_op_error (code);
8078       return error_mark_node;
8079     }
8080
8081   if (!converted)
8082     {
8083       if (TREE_TYPE (op0) != result_type)
8084         op0 = convert (result_type, op0);
8085       if (TREE_TYPE (op1) != result_type)
8086         op1 = convert (result_type, op1);
8087
8088       /* This can happen if one operand has a vector type, and the other
8089          has a different type.  */
8090       if (TREE_CODE (op0) == ERROR_MARK || TREE_CODE (op1) == ERROR_MARK)
8091         return error_mark_node;
8092     }
8093
8094   if (build_type == NULL_TREE)
8095     build_type = result_type;
8096
8097   {
8098     tree result = build2 (resultcode, build_type, op0, op1);
8099
8100     /* Treat expressions in initializers specially as they can't trap.  */
8101     result = require_constant_value ? fold_initializer (result)
8102                                     : fold (result);
8103
8104     if (final_type != 0)
8105       result = convert (final_type, result);
8106     return result;
8107   }
8108 }
8109
8110
8111 /* Convert EXPR to be a truth-value, validating its type for this
8112    purpose.  */
8113
8114 tree
8115 c_objc_common_truthvalue_conversion (tree expr)
8116 {
8117   switch (TREE_CODE (TREE_TYPE (expr)))
8118     {
8119     case ARRAY_TYPE:
8120       error ("used array that cannot be converted to pointer where scalar is required");
8121       return error_mark_node;
8122
8123     case RECORD_TYPE:
8124       error ("used struct type value where scalar is required");
8125       return error_mark_node;
8126
8127     case UNION_TYPE:
8128       error ("used union type value where scalar is required");
8129       return error_mark_node;
8130
8131     case FUNCTION_TYPE:
8132       gcc_unreachable ();
8133
8134     default:
8135       break;
8136     }
8137
8138   /* ??? Should we also give an error for void and vectors rather than
8139      leaving those to give errors later?  */
8140   return c_common_truthvalue_conversion (expr);
8141 }
8142 \f
8143
8144 /* Convert EXPR to a contained DECL, updating *TC, *TI and *SE as
8145    required.  */
8146
8147 tree
8148 c_expr_to_decl (tree expr, bool *tc ATTRIBUTE_UNUSED,
8149                 bool *ti ATTRIBUTE_UNUSED, bool *se)
8150 {
8151   if (TREE_CODE (expr) == COMPOUND_LITERAL_EXPR)
8152     {
8153       tree decl = COMPOUND_LITERAL_EXPR_DECL (expr);
8154       /* Executing a compound literal inside a function reinitializes
8155          it.  */
8156       if (!TREE_STATIC (decl))
8157         *se = true;
8158       return decl;
8159     }
8160   else
8161     return expr;
8162 }