gcc/c-typeck.c

   1 /* Build expressions with type checking for C compiler.
   2    Copyright (C) 1987, 1988, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20 02111-1307, USA.  */
  21
  22
  23 /* This file is part of the C front end.
  24    It contains routines to build C expressions given their operands,
  25    including computing the types of the result, C-specific error checks,
  26    and some optimization.  */
  27
  28 #include "config.h"
  29 #include "system.h"
  30 #include "coretypes.h"
  31 #include "tm.h"
  32 #include "rtl.h"
  33 #include "tree.h"
  34 #include "langhooks.h"
  35 #include "c-tree.h"
  36 #include "tm_p.h"
  37 #include "flags.h"
  38 #include "output.h"
  39 #include "expr.h"
  40 #include "toplev.h"
  41 #include "intl.h"
  42 #include "ggc.h"
  43 #include "target.h"
  44 #include "tree-iterator.h"
  45 #include "tree-gimple.h"
  46 #include "tree-flow.h"
  47
  48 /* Possible cases of implicit bad conversions.  Used to select
  49    diagnostic messages in convert_for_assignment.  */
  50 enum impl_conv {
  51   ic_argpass,
  52   ic_argpass_nonproto,
  53   ic_assign,
  54   ic_init,
  55   ic_return
  56 };
  57
  58 /* The level of nesting inside "__alignof__".  */
  59 int in_alignof;
  60
  61 /* The level of nesting inside "sizeof".  */
  62 int in_sizeof;
  63
  64 /* The level of nesting inside "typeof".  */
  65 int in_typeof;
  66
  67 struct c_label_context *label_context_stack;
  68
  69 /* Nonzero if we've already printed a "missing braces around initializer"
  70    message within this initializer.  */
  71 static int missing_braces_mentioned;
  72
  73 static int require_constant_value;
  74 static int require_constant_elements;
  75
  76 static tree qualify_type (tree, tree);
  77 static int tagged_types_tu_compatible_p (tree, tree);
  78 static int comp_target_types (tree, tree, int);
  79 static int function_types_compatible_p (tree, tree);
  80 static int type_lists_compatible_p (tree, tree);
  81 static tree decl_constant_value_for_broken_optimization (tree);
  82 static tree default_function_array_conversion (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 abort 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 tree
 622 common_type (tree t1, tree t2)
 623 {
 624   if (TREE_CODE (t1) == ENUMERAL_TYPE)
 625     t1 = c_common_type_for_size (TYPE_PRECISION (t1), 1);
 626   if (TREE_CODE (t2) == ENUMERAL_TYPE)
 627     t2 = c_common_type_for_size (TYPE_PRECISION (t2), 1);
 628   return c_common_type (t1, t2);
 629 }
 630 \f
 631 /* Return 1 if TYPE1 and TYPE2 are compatible types for assignment
 632    or various other operations.  Return 2 if they are compatible
 633    but a warning may be needed if you use them together.  */
 634
 635 int
 636 comptypes (tree type1, tree type2)
 637 {
 638   tree t1 = type1;
 639   tree t2 = type2;
 640   int attrval, val;
 641
 642   /* Suppress errors caused by previously reported errors.  */
 643
 644   if (t1 == t2 || !t1 || !t2
 645       || TREE_CODE (t1) == ERROR_MARK || TREE_CODE (t2) == ERROR_MARK)
 646     return 1;
 647
 648   /* If either type is the internal version of sizetype, return the
 649      language version.  */
 650   if (TREE_CODE (t1) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t1)
 651       && TYPE_ORIG_SIZE_TYPE (t1))
 652     t1 = TYPE_ORIG_SIZE_TYPE (t1);
 653
 654   if (TREE_CODE (t2) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t2)
 655       && TYPE_ORIG_SIZE_TYPE (t2))
 656     t2 = TYPE_ORIG_SIZE_TYPE (t2);
 657
 658
 659   /* Enumerated types are compatible with integer types, but this is
 660      not transitive: two enumerated types in the same translation unit
 661      are compatible with each other only if they are the same type.  */
 662
 663   if (TREE_CODE (t1) == ENUMERAL_TYPE && TREE_CODE (t2) != ENUMERAL_TYPE)
 664     t1 = c_common_type_for_size (TYPE_PRECISION (t1), TYPE_UNSIGNED (t1));
 665   else if (TREE_CODE (t2) == ENUMERAL_TYPE && TREE_CODE (t1) != ENUMERAL_TYPE)
 666     t2 = c_common_type_for_size (TYPE_PRECISION (t2), TYPE_UNSIGNED (t2));
 667
 668   if (t1 == t2)
 669     return 1;
 670
 671   /* Different classes of types can't be compatible.  */
 672
 673   if (TREE_CODE (t1) != TREE_CODE (t2))
 674     return 0;
 675
 676   /* Qualifiers must match. C99 6.7.3p9 */
 677
 678   if (TYPE_QUALS (t1) != TYPE_QUALS (t2))
 679     return 0;
 680
 681   /* Allow for two different type nodes which have essentially the same
 682      definition.  Note that we already checked for equality of the type
 683      qualifiers (just above).  */
 684
 685   if (TREE_CODE (t1) != ARRAY_TYPE
 686       && TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
 687     return 1;
 688
 689   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
 690   if (!(attrval = targetm.comp_type_attributes (t1, t2)))
 691      return 0;
 692
 693   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
 694   val = 0;
 695
 696   switch (TREE_CODE (t1))
 697     {
 698     case POINTER_TYPE:
 699       /* We must give ObjC the first crack at comparing pointers, since
 700            protocol qualifiers may be involved.  */
 701       if (c_dialect_objc () && (val = objc_comptypes (t1, t2, 0)) >= 0)
 702         break;
 703       /* Do not remove mode or aliasing information.  */
 704       if (TYPE_MODE (t1) != TYPE_MODE (t2)
 705           || TYPE_REF_CAN_ALIAS_ALL (t1) != TYPE_REF_CAN_ALIAS_ALL (t2))
 706         break;
 707       val = (TREE_TYPE (t1) == TREE_TYPE (t2)
 708              ? 1 : comptypes (TREE_TYPE (t1), TREE_TYPE (t2)));
 709       break;
 710
 711     case FUNCTION_TYPE:
 712       val = function_types_compatible_p (t1, t2);
 713       break;
 714
 715     case ARRAY_TYPE:
 716       {
 717         tree d1 = TYPE_DOMAIN (t1);
 718         tree d2 = TYPE_DOMAIN (t2);
 719         bool d1_variable, d2_variable;
 720         bool d1_zero, d2_zero;
 721         val = 1;
 722
 723         /* Target types must match incl. qualifiers.  */
 724         if (TREE_TYPE (t1) != TREE_TYPE (t2)
 725             && 0 == (val = comptypes (TREE_TYPE (t1), TREE_TYPE (t2))))
 726           return 0;
 727
 728         /* Sizes must match unless one is missing or variable.  */
 729         if (d1 == 0 || d2 == 0 || d1 == d2)
 730           break;
 731
 732         d1_zero = !TYPE_MAX_VALUE (d1);
 733         d2_zero = !TYPE_MAX_VALUE (d2);
 734
 735         d1_variable = (!d1_zero
 736                        && (TREE_CODE (TYPE_MIN_VALUE (d1)) != INTEGER_CST
 737                            || TREE_CODE (TYPE_MAX_VALUE (d1)) != INTEGER_CST));
 738         d2_variable = (!d2_zero
 739                        && (TREE_CODE (TYPE_MIN_VALUE (d2)) != INTEGER_CST
 740                            || TREE_CODE (TYPE_MAX_VALUE (d2)) != INTEGER_CST));
 741
 742         if (d1_variable || d2_variable)
 743           break;
 744         if (d1_zero && d2_zero)
 745           break;
 746         if (d1_zero || d2_zero
 747             || !tree_int_cst_equal (TYPE_MIN_VALUE (d1), TYPE_MIN_VALUE (d2))
 748             || !tree_int_cst_equal (TYPE_MAX_VALUE (d1), TYPE_MAX_VALUE (d2)))
 749           val = 0;
 750
 751         break;
 752       }
 753
 754     case RECORD_TYPE:
 755       /* We are dealing with two distinct structs.  In assorted Objective-C
 756          corner cases, however, these can still be deemed equivalent.  */
 757       if (c_dialect_objc () && objc_comptypes (t1, t2, 0) == 1)
 758         val = 1;
 759
 760     case ENUMERAL_TYPE:
 761     case UNION_TYPE:
 762       if (val != 1 && !same_translation_unit_p (t1, t2))
 763         val = tagged_types_tu_compatible_p (t1, t2);
 764       break;
 765
 766     case VECTOR_TYPE:
 767       val = TYPE_VECTOR_SUBPARTS (t1) == TYPE_VECTOR_SUBPARTS (t2)
 768             && comptypes (TREE_TYPE (t1), TREE_TYPE (t2));
 769       break;
 770
 771     default:
 772       break;
 773     }
 774   return attrval == 2 && val == 1 ? 2 : val;
 775 }
 776
 777 /* Return 1 if TTL and TTR are pointers to types that are equivalent,
 778    ignoring their qualifiers.  REFLEXIVE is only used by ObjC - set it
 779    to 1 or 0 depending if the check of the pointer types is meant to
 780    be reflexive or not (typically, assignments are not reflexive,
 781    while comparisons are reflexive).
 782 */
 783
 784 static int
 785 comp_target_types (tree ttl, tree ttr, int reflexive)
 786 {
 787   int val;
 788   tree mvl, mvr;
 789
 790   /* Give objc_comptypes a crack at letting these types through.  */
 791   if ((val = objc_comptypes (ttl, ttr, reflexive)) >= 0)
 792     return val;
 793
 794   /* Do not lose qualifiers on element types of array types that are
 795      pointer targets by taking their TYPE_MAIN_VARIANT.  */
 796   mvl = TREE_TYPE (ttl);
 797   mvr = TREE_TYPE (ttr);
 798   if (TREE_CODE (mvl) != ARRAY_TYPE)
 799     mvl = TYPE_MAIN_VARIANT (mvl);
 800   if (TREE_CODE (mvr) != ARRAY_TYPE)
 801     mvr = TYPE_MAIN_VARIANT (mvr);
 802   val = comptypes (mvl, mvr);
 803
 804   if (val == 2 && pedantic)
 805     pedwarn ("types are not quite compatible");
 806   return val;
 807 }
 808 \f
 809 /* Subroutines of `comptypes'.  */
 810
 811 /* Determine whether two trees derive from the same translation unit.
 812    If the CONTEXT chain ends in a null, that tree's context is still
 813    being parsed, so if two trees have context chains ending in null,
 814    they're in the same translation unit.  */
 815 int
 816 same_translation_unit_p (tree t1, tree t2)
 817 {
 818   while (t1 && TREE_CODE (t1) != TRANSLATION_UNIT_DECL)
 819     switch (TREE_CODE_CLASS (TREE_CODE (t1)))
 820       {
 821       case tcc_declaration:
 822         t1 = DECL_CONTEXT (t1); break;
 823       case tcc_type:
 824         t1 = TYPE_CONTEXT (t1); break;
 825       case tcc_exceptional:
 826         t1 = BLOCK_SUPERCONTEXT (t1); break;  /* assume block */
 827       default: gcc_unreachable ();
 828       }
 829
 830   while (t2 && TREE_CODE (t2) != TRANSLATION_UNIT_DECL)
 831     switch (TREE_CODE_CLASS (TREE_CODE (t2)))
 832       {
 833       case tcc_declaration:
 834         t2 = DECL_CONTEXT (t2); break;
 835       case tcc_type:
 836         t2 = TYPE_CONTEXT (t2); break;
 837       case tcc_exceptional:
 838         t2 = BLOCK_SUPERCONTEXT (t2); break;  /* assume block */
 839       default: gcc_unreachable ();
 840       }
 841
 842   return t1 == t2;
 843 }
 844
 845 /* The C standard says that two structures in different translation
 846    units are compatible with each other only if the types of their
 847    fields are compatible (among other things).  So, consider two copies
 848    of this structure:  */
 849
 850 struct tagged_tu_seen {
 851   const struct tagged_tu_seen * next;
 852   tree t1;
 853   tree t2;
 854 };
 855
 856 /* Can they be compatible with each other?  We choose to break the
 857    recursion by allowing those types to be compatible.  */
 858
 859 static const struct tagged_tu_seen * tagged_tu_seen_base;
 860
 861 /* Return 1 if two 'struct', 'union', or 'enum' types T1 and T2 are
 862    compatible.  If the two types are not the same (which has been
 863    checked earlier), this can only happen when multiple translation
 864    units are being compiled.  See C99 6.2.7 paragraph 1 for the exact
 865    rules.  */
 866
 867 static int
 868 tagged_types_tu_compatible_p (tree t1, tree t2)
 869 {
 870   tree s1, s2;
 871   bool needs_warning = false;
 872
 873   /* We have to verify that the tags of the types are the same.  This
 874      is harder than it looks because this may be a typedef, so we have
 875      to go look at the original type.  It may even be a typedef of a
 876      typedef...
 877      In the case of compiler-created builtin structs the TYPE_DECL
 878      may be a dummy, with no DECL_ORIGINAL_TYPE.  Don't fault.  */
 879   while (TYPE_NAME (t1)
 880          && TREE_CODE (TYPE_NAME (t1)) == TYPE_DECL
 881          && DECL_ORIGINAL_TYPE (TYPE_NAME (t1)))
 882     t1 = DECL_ORIGINAL_TYPE (TYPE_NAME (t1));
 883
 884   while (TYPE_NAME (t2)
 885          && TREE_CODE (TYPE_NAME (t2)) == TYPE_DECL
 886          && DECL_ORIGINAL_TYPE (TYPE_NAME (t2)))
 887     t2 = DECL_ORIGINAL_TYPE (TYPE_NAME (t2));
 888
 889   /* C90 didn't have the requirement that the two tags be the same.  */
 890   if (flag_isoc99 && TYPE_NAME (t1) != TYPE_NAME (t2))
 891     return 0;
 892
 893   /* C90 didn't say what happened if one or both of the types were
 894      incomplete; we choose to follow C99 rules here, which is that they
 895      are compatible.  */
 896   if (TYPE_SIZE (t1) == NULL
 897       || TYPE_SIZE (t2) == NULL)
 898     return 1;
 899
 900   {
 901     const struct tagged_tu_seen * tts_i;
 902     for (tts_i = tagged_tu_seen_base; tts_i != NULL; tts_i = tts_i->next)
 903       if (tts_i->t1 == t1 && tts_i->t2 == t2)
 904         return 1;
 905   }
 906
 907   switch (TREE_CODE (t1))
 908     {
 909     case ENUMERAL_TYPE:
 910       {
 911
 912         /* Speed up the case where the type values are in the same order.  */
 913         tree tv1 = TYPE_VALUES (t1);
 914         tree tv2 = TYPE_VALUES (t2);
 915
 916         if (tv1 == tv2)
 917           return 1;
 918
 919         for (;tv1 && tv2; tv1 = TREE_CHAIN (tv1), tv2 = TREE_CHAIN (tv2))
 920           {
 921             if (TREE_PURPOSE (tv1) != TREE_PURPOSE (tv2))
 922               break;
 923             if (simple_cst_equal (TREE_VALUE (tv1), TREE_VALUE (tv2)) != 1)
 924               return 0;
 925           }
 926
 927         if (tv1 == NULL_TREE && tv2 == NULL_TREE)
 928           return 1;
 929         if (tv1 == NULL_TREE || tv2 == NULL_TREE)
 930           return 0;
 931
 932         if (list_length (TYPE_VALUES (t1)) != list_length (TYPE_VALUES (t2)))
 933           return 0;
 934
 935         for (s1 = TYPE_VALUES (t1); s1; s1 = TREE_CHAIN (s1))
 936           {
 937             s2 = purpose_member (TREE_PURPOSE (s1), TYPE_VALUES (t2));
 938             if (s2 == NULL
 939                 || simple_cst_equal (TREE_VALUE (s1), TREE_VALUE (s2)) != 1)
 940               return 0;
 941           }
 942         return 1;
 943       }
 944
 945     case UNION_TYPE:
 946       {
 947         if (list_length (TYPE_FIELDS (t1)) != list_length (TYPE_FIELDS (t2)))
 948           return 0;
 949
 950         for (s1 = TYPE_FIELDS (t1); s1; s1 = TREE_CHAIN (s1))
 951           {
 952             bool ok = false;
 953             struct tagged_tu_seen tts;
 954
 955             tts.next = tagged_tu_seen_base;
 956             tts.t1 = t1;
 957             tts.t2 = t2;
 958             tagged_tu_seen_base = &tts;
 959
 960             if (DECL_NAME (s1) != NULL)
 961               for (s2 = TYPE_FIELDS (t2); s2; s2 = TREE_CHAIN (s2))
 962                 if (DECL_NAME (s1) == DECL_NAME (s2))
 963                   {
 964                     int result;
 965                     result = comptypes (TREE_TYPE (s1), TREE_TYPE (s2));
 966                     if (result == 0)
 967                       break;
 968                     if (result == 2)
 969                       needs_warning = true;
 970
 971                     if (TREE_CODE (s1) == FIELD_DECL
 972                         && simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
 973                                              DECL_FIELD_BIT_OFFSET (s2)) != 1)
 974                       break;
 975
 976                     ok = true;
 977                     break;
 978                   }
 979             tagged_tu_seen_base = tts.next;
 980             if (!ok)
 981               return 0;
 982           }
 983         return needs_warning ? 2 : 1;
 984       }
 985
 986     case RECORD_TYPE:
 987       {
 988         struct tagged_tu_seen tts;
 989
 990         tts.next = tagged_tu_seen_base;
 991         tts.t1 = t1;
 992         tts.t2 = t2;
 993         tagged_tu_seen_base = &tts;
 994
 995         for (s1 = TYPE_FIELDS (t1), s2 = TYPE_FIELDS (t2);
 996              s1 && s2;
 997              s1 = TREE_CHAIN (s1), s2 = TREE_CHAIN (s2))
 998           {
 999             int result;
1000             if (TREE_CODE (s1) != TREE_CODE (s2)
1001                 || DECL_NAME (s1) != DECL_NAME (s2))
1002               break;
1003             result = comptypes (TREE_TYPE (s1), TREE_TYPE (s2));
1004             if (result == 0)
1005               break;
1006             if (result == 2)
1007               needs_warning = true;
1008
1009             if (TREE_CODE (s1) == FIELD_DECL
1010                 && simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
1011                                      DECL_FIELD_BIT_OFFSET (s2)) != 1)
1012               break;
1013           }
1014         tagged_tu_seen_base = tts.next;
1015         if (s1 && s2)
1016           return 0;
1017         return needs_warning ? 2 : 1;
1018       }
1019
1020     default:
1021       gcc_unreachable ();
1022     }
1023 }
1024
1025 /* Return 1 if two function types F1 and F2 are compatible.
1026    If either type specifies no argument types,
1027    the other must specify a fixed number of self-promoting arg types.
1028    Otherwise, if one type specifies only the number of arguments,
1029    the other must specify that number of self-promoting arg types.
1030    Otherwise, the argument types must match.  */
1031
1032 static int
1033 function_types_compatible_p (tree f1, tree f2)
1034 {
1035   tree args1, args2;
1036   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
1037   int val = 1;
1038   int val1;
1039   tree ret1, ret2;
1040
1041   ret1 = TREE_TYPE (f1);
1042   ret2 = TREE_TYPE (f2);
1043
1044   /* 'volatile' qualifiers on a function's return type used to mean
1045      the function is noreturn.  */
1046   if (TYPE_VOLATILE (ret1) != TYPE_VOLATILE (ret2))
1047     pedwarn ("function return types not compatible due to %<volatile%>");
1048   if (TYPE_VOLATILE (ret1))
1049     ret1 = build_qualified_type (TYPE_MAIN_VARIANT (ret1),
1050                                  TYPE_QUALS (ret1) & ~TYPE_QUAL_VOLATILE);
1051   if (TYPE_VOLATILE (ret2))
1052     ret2 = build_qualified_type (TYPE_MAIN_VARIANT (ret2),
1053                                  TYPE_QUALS (ret2) & ~TYPE_QUAL_VOLATILE);
1054   val = comptypes (ret1, ret2);
1055   if (val == 0)
1056     return 0;
1057
1058   args1 = TYPE_ARG_TYPES (f1);
1059   args2 = TYPE_ARG_TYPES (f2);
1060
1061   /* An unspecified parmlist matches any specified parmlist
1062      whose argument types don't need default promotions.  */
1063
1064   if (args1 == 0)
1065     {
1066       if (!self_promoting_args_p (args2))
1067         return 0;
1068       /* If one of these types comes from a non-prototype fn definition,
1069          compare that with the other type's arglist.
1070          If they don't match, ask for a warning (but no error).  */
1071       if (TYPE_ACTUAL_ARG_TYPES (f1)
1072           && 1 != type_lists_compatible_p (args2, TYPE_ACTUAL_ARG_TYPES (f1)))
1073         val = 2;
1074       return val;
1075     }
1076   if (args2 == 0)
1077     {
1078       if (!self_promoting_args_p (args1))
1079         return 0;
1080       if (TYPE_ACTUAL_ARG_TYPES (f2)
1081           && 1 != type_lists_compatible_p (args1, TYPE_ACTUAL_ARG_TYPES (f2)))
1082         val = 2;
1083       return val;
1084     }
1085
1086   /* Both types have argument lists: compare them and propagate results.  */
1087   val1 = type_lists_compatible_p (args1, args2);
1088   return val1 != 1 ? val1 : val;
1089 }
1090
1091 /* Check two lists of types for compatibility,
1092    returning 0 for incompatible, 1 for compatible,
1093    or 2 for compatible with warning.  */
1094
1095 static int
1096 type_lists_compatible_p (tree args1, tree args2)
1097 {
1098   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
1099   int val = 1;
1100   int newval = 0;
1101
1102   while (1)
1103     {
1104       tree a1, mv1, a2, mv2;
1105       if (args1 == 0 && args2 == 0)
1106         return val;
1107       /* If one list is shorter than the other,
1108          they fail to match.  */
1109       if (args1 == 0 || args2 == 0)
1110         return 0;
1111       mv1 = a1 = TREE_VALUE (args1);
1112       mv2 = a2 = TREE_VALUE (args2);
1113       if (mv1 && mv1 != error_mark_node && TREE_CODE (mv1) != ARRAY_TYPE)
1114         mv1 = TYPE_MAIN_VARIANT (mv1);
1115       if (mv2 && mv2 != error_mark_node && TREE_CODE (mv2) != ARRAY_TYPE)
1116         mv2 = TYPE_MAIN_VARIANT (mv2);
1117       /* A null pointer instead of a type
1118          means there is supposed to be an argument
1119          but nothing is specified about what type it has.
1120          So match anything that self-promotes.  */
1121       if (a1 == 0)
1122         {
1123           if (c_type_promotes_to (a2) != a2)
1124             return 0;
1125         }
1126       else if (a2 == 0)
1127         {
1128           if (c_type_promotes_to (a1) != a1)
1129             return 0;
1130         }
1131       /* If one of the lists has an error marker, ignore this arg.  */
1132       else if (TREE_CODE (a1) == ERROR_MARK
1133                || TREE_CODE (a2) == ERROR_MARK)
1134         ;
1135       else if (!(newval = comptypes (mv1, mv2)))
1136         {
1137           /* Allow  wait (union {union wait *u; int *i} *)
1138              and  wait (union wait *)  to be compatible.  */
1139           if (TREE_CODE (a1) == UNION_TYPE
1140               && (TYPE_NAME (a1) == 0
1141                   || TYPE_TRANSPARENT_UNION (a1))
1142               && TREE_CODE (TYPE_SIZE (a1)) == INTEGER_CST
1143               && tree_int_cst_equal (TYPE_SIZE (a1),
1144                                      TYPE_SIZE (a2)))
1145             {
1146               tree memb;
1147               for (memb = TYPE_FIELDS (a1);
1148                    memb; memb = TREE_CHAIN (memb))
1149                 {
1150                   tree mv3 = TREE_TYPE (memb);
1151                   if (mv3 && mv3 != error_mark_node
1152                       && TREE_CODE (mv3) != ARRAY_TYPE)
1153                     mv3 = TYPE_MAIN_VARIANT (mv3);
1154                   if (comptypes (mv3, mv2))
1155                     break;
1156                 }
1157               if (memb == 0)
1158                 return 0;
1159             }
1160           else if (TREE_CODE (a2) == UNION_TYPE
1161                    && (TYPE_NAME (a2) == 0
1162                        || TYPE_TRANSPARENT_UNION (a2))
1163                    && TREE_CODE (TYPE_SIZE (a2)) == INTEGER_CST
1164                    && tree_int_cst_equal (TYPE_SIZE (a2),
1165                                           TYPE_SIZE (a1)))
1166             {
1167               tree memb;
1168               for (memb = TYPE_FIELDS (a2);
1169                    memb; memb = TREE_CHAIN (memb))
1170                 {
1171                   tree mv3 = TREE_TYPE (memb);
1172                   if (mv3 && mv3 != error_mark_node
1173                       && TREE_CODE (mv3) != ARRAY_TYPE)
1174                     mv3 = TYPE_MAIN_VARIANT (mv3);
1175                   if (comptypes (mv3, mv1))
1176                     break;
1177                 }
1178               if (memb == 0)
1179                 return 0;
1180             }
1181           else
1182             return 0;
1183         }
1184
1185       /* comptypes said ok, but record if it said to warn.  */
1186       if (newval > val)
1187         val = newval;
1188
1189       args1 = TREE_CHAIN (args1);
1190       args2 = TREE_CHAIN (args2);
1191     }
1192 }
1193 \f
1194 /* Compute the size to increment a pointer by.  */
1195
1196 static tree
1197 c_size_in_bytes (tree type)
1198 {
1199   enum tree_code code = TREE_CODE (type);
1200
1201   if (code == FUNCTION_TYPE || code == VOID_TYPE || code == ERROR_MARK)
1202     return size_one_node;
1203
1204   if (!COMPLETE_OR_VOID_TYPE_P (type))
1205     {
1206       error ("arithmetic on pointer to an incomplete type");
1207       return size_one_node;
1208     }
1209
1210   /* Convert in case a char is more than one unit.  */
1211   return size_binop (CEIL_DIV_EXPR, TYPE_SIZE_UNIT (type),
1212                      size_int (TYPE_PRECISION (char_type_node)
1213                                / BITS_PER_UNIT));
1214 }
1215 \f
1216 /* Return either DECL or its known constant value (if it has one).  */
1217
1218 tree
1219 decl_constant_value (tree decl)
1220 {
1221   if (/* Don't change a variable array bound or initial value to a constant
1222          in a place where a variable is invalid.  Note that DECL_INITIAL
1223          isn't valid for a PARM_DECL.  */
1224       current_function_decl != 0
1225       && TREE_CODE (decl) != PARM_DECL
1226       && !TREE_THIS_VOLATILE (decl)
1227       && TREE_READONLY (decl)
1228       && DECL_INITIAL (decl) != 0
1229       && TREE_CODE (DECL_INITIAL (decl)) != ERROR_MARK
1230       /* This is invalid if initial value is not constant.
1231          If it has either a function call, a memory reference,
1232          or a variable, then re-evaluating it could give different results.  */
1233       && TREE_CONSTANT (DECL_INITIAL (decl))
1234       /* Check for cases where this is sub-optimal, even though valid.  */
1235       && TREE_CODE (DECL_INITIAL (decl)) != CONSTRUCTOR)
1236     return DECL_INITIAL (decl);
1237   return decl;
1238 }
1239
1240 /* Return either DECL or its known constant value (if it has one), but
1241    return DECL if pedantic or DECL has mode BLKmode.  This is for
1242    bug-compatibility with the old behavior of decl_constant_value
1243    (before GCC 3.0); every use of this function is a bug and it should
1244    be removed before GCC 3.1.  It is not appropriate to use pedantic
1245    in a way that affects optimization, and BLKmode is probably not the
1246    right test for avoiding misoptimizations either.  */
1247
1248 static tree
1249 decl_constant_value_for_broken_optimization (tree decl)
1250 {
1251   if (pedantic || DECL_MODE (decl) == BLKmode)
1252     return decl;
1253   else
1254     return decl_constant_value (decl);
1255 }
1256
1257
1258 /* Perform the default conversion of arrays and functions to pointers.
1259    Return the result of converting EXP.  For any other expression, just
1260    return EXP.  */
1261
1262 static tree
1263 default_function_array_conversion (tree exp)
1264 {
1265   tree orig_exp;
1266   tree type = TREE_TYPE (exp);
1267   enum tree_code code = TREE_CODE (type);
1268   int not_lvalue = 0;
1269
1270   /* Strip NON_LVALUE_EXPRs and no-op conversions, since we aren't using as
1271      an lvalue.
1272
1273      Do not use STRIP_NOPS here!  It will remove conversions from pointer
1274      to integer and cause infinite recursion.  */
1275   orig_exp = exp;
1276   while (TREE_CODE (exp) == NON_LVALUE_EXPR
1277          || (TREE_CODE (exp) == NOP_EXPR
1278              && TREE_TYPE (TREE_OPERAND (exp, 0)) == TREE_TYPE (exp)))
1279     {
1280       if (TREE_CODE (exp) == NON_LVALUE_EXPR)
1281         not_lvalue = 1;
1282       exp = TREE_OPERAND (exp, 0);
1283     }
1284
1285   if (TREE_NO_WARNING (orig_exp))
1286     TREE_NO_WARNING (exp) = 1;
1287
1288   if (code == FUNCTION_TYPE)
1289     {
1290       return build_unary_op (ADDR_EXPR, exp, 0);
1291     }
1292   if (code == ARRAY_TYPE)
1293     {
1294       tree adr;
1295       tree restype = TREE_TYPE (type);
1296       tree ptrtype;
1297       int constp = 0;
1298       int volatilep = 0;
1299       int lvalue_array_p;
1300
1301       if (REFERENCE_CLASS_P (exp) || DECL_P (exp))
1302         {
1303           constp = TREE_READONLY (exp);
1304           volatilep = TREE_THIS_VOLATILE (exp);
1305         }
1306
1307       if (TYPE_QUALS (type) || constp || volatilep)
1308         restype
1309           = c_build_qualified_type (restype,
1310                                     TYPE_QUALS (type)
1311                                     | (constp * TYPE_QUAL_CONST)
1312                                     | (volatilep * TYPE_QUAL_VOLATILE));
1313
1314       if (TREE_CODE (exp) == INDIRECT_REF)
1315         return convert (build_pointer_type (restype),
1316                         TREE_OPERAND (exp, 0));
1317
1318       if (TREE_CODE (exp) == COMPOUND_EXPR)
1319         {
1320           tree op1 = default_conversion (TREE_OPERAND (exp, 1));
1321           return build2 (COMPOUND_EXPR, TREE_TYPE (op1),
1322                          TREE_OPERAND (exp, 0), op1);
1323         }
1324
1325       lvalue_array_p = !not_lvalue && lvalue_p (exp);
1326       if (!flag_isoc99 && !lvalue_array_p)
1327         {
1328           /* Before C99, non-lvalue arrays do not decay to pointers.
1329              Normally, using such an array would be invalid; but it can
1330              be used correctly inside sizeof or as a statement expression.
1331              Thus, do not give an error here; an error will result later.  */
1332           return exp;
1333         }
1334
1335       ptrtype = build_pointer_type (restype);
1336
1337       if (TREE_CODE (exp) == VAR_DECL)
1338         {
1339           /* We are making an ADDR_EXPR of ptrtype.  This is a valid
1340              ADDR_EXPR because it's the best way of representing what
1341              happens in C when we take the address of an array and place
1342              it in a pointer to the element type.  */
1343           adr = build1 (ADDR_EXPR, ptrtype, exp);
1344           if (!c_mark_addressable (exp))
1345             return error_mark_node;
1346           TREE_SIDE_EFFECTS (adr) = 0;   /* Default would be, same as EXP.  */
1347           return adr;
1348         }
1349       /* This way is better for a COMPONENT_REF since it can
1350          simplify the offset for a component.  */
1351       adr = build_unary_op (ADDR_EXPR, exp, 1);
1352       return convert (ptrtype, adr);
1353     }
1354   return exp;
1355 }
1356
1357
1358 /* EXP is an expression of integer type.  Apply the integer promotions
1359    to it and return the promoted value.  */
1360
1361 tree
1362 perform_integral_promotions (tree exp)
1363 {
1364   tree type = TREE_TYPE (exp);
1365   enum tree_code code = TREE_CODE (type);
1366
1367   gcc_assert (INTEGRAL_TYPE_P (type));
1368
1369   /* Normally convert enums to int,
1370      but convert wide enums to something wider.  */
1371   if (code == ENUMERAL_TYPE)
1372     {
1373       type = c_common_type_for_size (MAX (TYPE_PRECISION (type),
1374                                           TYPE_PRECISION (integer_type_node)),
1375                                      ((TYPE_PRECISION (type)
1376                                        >= TYPE_PRECISION (integer_type_node))
1377                                       && TYPE_UNSIGNED (type)));
1378
1379       return convert (type, exp);
1380     }
1381
1382   /* ??? This should no longer be needed now bit-fields have their
1383      proper types.  */
1384   if (TREE_CODE (exp) == COMPONENT_REF
1385       && DECL_C_BIT_FIELD (TREE_OPERAND (exp, 1))
1386       /* If it's thinner than an int, promote it like a
1387          c_promoting_integer_type_p, otherwise leave it alone.  */
1388       && 0 > compare_tree_int (DECL_SIZE (TREE_OPERAND (exp, 1)),
1389                                TYPE_PRECISION (integer_type_node)))
1390     return convert (integer_type_node, exp);
1391
1392   if (c_promoting_integer_type_p (type))
1393     {
1394       /* Preserve unsignedness if not really getting any wider.  */
1395       if (TYPE_UNSIGNED (type)
1396           && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
1397         return convert (unsigned_type_node, exp);
1398
1399       return convert (integer_type_node, exp);
1400     }
1401
1402   return exp;
1403 }
1404
1405
1406 /* Perform default promotions for C data used in expressions.
1407    Arrays and functions are converted to pointers;
1408    enumeral types or short or char, to int.
1409    In addition, manifest constants symbols are replaced by their values.  */
1410
1411 tree
1412 default_conversion (tree exp)
1413 {
1414   tree orig_exp;
1415   tree type = TREE_TYPE (exp);
1416   enum tree_code code = TREE_CODE (type);
1417
1418   if (code == FUNCTION_TYPE || code == ARRAY_TYPE)
1419     return default_function_array_conversion (exp);
1420
1421   /* Constants can be used directly unless they're not loadable.  */
1422   if (TREE_CODE (exp) == CONST_DECL)
1423     exp = DECL_INITIAL (exp);
1424
1425   /* Replace a nonvolatile const static variable with its value unless
1426      it is an array, in which case we must be sure that taking the
1427      address of the array produces consistent results.  */
1428   else if (optimize && TREE_CODE (exp) == VAR_DECL && code != ARRAY_TYPE)
1429     {
1430       exp = decl_constant_value_for_broken_optimization (exp);
1431       type = TREE_TYPE (exp);
1432     }
1433
1434   /* Strip no-op conversions.  */
1435   orig_exp = exp;
1436   STRIP_TYPE_NOPS (exp);
1437
1438   if (TREE_NO_WARNING (orig_exp))
1439     TREE_NO_WARNING (exp) = 1;
1440
1441   if (INTEGRAL_TYPE_P (type))
1442     return perform_integral_promotions (exp);
1443
1444   if (code == VOID_TYPE)
1445     {
1446       error ("void value not ignored as it ought to be");
1447       return error_mark_node;
1448     }
1449   return exp;
1450 }
1451 \f
1452 /* Look up COMPONENT in a structure or union DECL.
1453
1454    If the component name is not found, returns NULL_TREE.  Otherwise,
1455    the return value is a TREE_LIST, with each TREE_VALUE a FIELD_DECL
1456    stepping down the chain to the component, which is in the last
1457    TREE_VALUE of the list.  Normally the list is of length one, but if
1458    the component is embedded within (nested) anonymous structures or
1459    unions, the list steps down the chain to the component.  */
1460
1461 static tree
1462 lookup_field (tree decl, tree component)
1463 {
1464   tree type = TREE_TYPE (decl);
1465   tree field;
1466
1467   /* If TYPE_LANG_SPECIFIC is set, then it is a sorted array of pointers
1468      to the field elements.  Use a binary search on this array to quickly
1469      find the element.  Otherwise, do a linear search.  TYPE_LANG_SPECIFIC
1470      will always be set for structures which have many elements.  */
1471
1472   if (TYPE_LANG_SPECIFIC (type) && TYPE_LANG_SPECIFIC (type)->s)
1473     {
1474       int bot, top, half;
1475       tree *field_array = &TYPE_LANG_SPECIFIC (type)->s->elts[0];
1476
1477       field = TYPE_FIELDS (type);
1478       bot = 0;
1479       top = TYPE_LANG_SPECIFIC (type)->s->len;
1480       while (top - bot > 1)
1481         {
1482           half = (top - bot + 1) >> 1;
1483           field = field_array[bot+half];
1484
1485           if (DECL_NAME (field) == NULL_TREE)
1486             {
1487               /* Step through all anon unions in linear fashion.  */
1488               while (DECL_NAME (field_array[bot]) == NULL_TREE)
1489                 {
1490                   field = field_array[bot++];
1491                   if (TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
1492                       || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
1493                     {
1494                       tree anon = lookup_field (field, component);
1495
1496                       if (anon)
1497                         return tree_cons (NULL_TREE, field, anon);
1498                     }
1499                 }
1500
1501               /* Entire record is only anon unions.  */
1502               if (bot > top)
1503                 return NULL_TREE;
1504
1505               /* Restart the binary search, with new lower bound.  */
1506               continue;
1507             }
1508
1509           if (DECL_NAME (field) == component)
1510             break;
1511           if (DECL_NAME (field) < component)
1512             bot += half;
1513           else
1514             top = bot + half;
1515         }
1516
1517       if (DECL_NAME (field_array[bot]) == component)
1518         field = field_array[bot];
1519       else if (DECL_NAME (field) != component)
1520         return NULL_TREE;
1521     }
1522   else
1523     {
1524       for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1525         {
1526           if (DECL_NAME (field) == NULL_TREE
1527               && (TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
1528                   || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE))
1529             {
1530               tree anon = lookup_field (field, component);
1531
1532               if (anon)
1533                 return tree_cons (NULL_TREE, field, anon);
1534             }
1535
1536           if (DECL_NAME (field) == component)
1537             break;
1538         }
1539
1540       if (field == NULL_TREE)
1541         return NULL_TREE;
1542     }
1543
1544   return tree_cons (NULL_TREE, field, NULL_TREE);
1545 }
1546
1547 /* Make an expression to refer to the COMPONENT field of
1548    structure or union value DATUM.  COMPONENT is an IDENTIFIER_NODE.  */
1549
1550 tree
1551 build_component_ref (tree datum, tree component)
1552 {
1553   tree type = TREE_TYPE (datum);
1554   enum tree_code code = TREE_CODE (type);
1555   tree field = NULL;
1556   tree ref;
1557
1558   if (!objc_is_public (datum, component))
1559     return error_mark_node;
1560
1561   /* See if there is a field or component with name COMPONENT.  */
1562
1563   if (code == RECORD_TYPE || code == UNION_TYPE)
1564     {
1565       if (!COMPLETE_TYPE_P (type))
1566         {
1567           c_incomplete_type_error (NULL_TREE, type);
1568           return error_mark_node;
1569         }
1570
1571       field = lookup_field (datum, component);
1572
1573       if (!field)
1574         {
1575           error ("%qT has no member named %qE", type, component);
1576           return error_mark_node;
1577         }
1578
1579       /* Chain the COMPONENT_REFs if necessary down to the FIELD.
1580          This might be better solved in future the way the C++ front
1581          end does it - by giving the anonymous entities each a
1582          separate name and type, and then have build_component_ref
1583          recursively call itself.  We can't do that here.  */
1584       do
1585         {
1586           tree subdatum = TREE_VALUE (field);
1587
1588           if (TREE_TYPE (subdatum) == error_mark_node)
1589             return error_mark_node;
1590
1591           ref = build3 (COMPONENT_REF, TREE_TYPE (subdatum), datum, subdatum,
1592                         NULL_TREE);
1593           if (TREE_READONLY (datum) || TREE_READONLY (subdatum))
1594             TREE_READONLY (ref) = 1;
1595           if (TREE_THIS_VOLATILE (datum) || TREE_THIS_VOLATILE (subdatum))
1596             TREE_THIS_VOLATILE (ref) = 1;
1597
1598           if (TREE_DEPRECATED (subdatum))
1599             warn_deprecated_use (subdatum);
1600
1601           datum = ref;
1602
1603           field = TREE_CHAIN (field);
1604         }
1605       while (field);
1606
1607       return ref;
1608     }
1609   else if (code != ERROR_MARK)
1610     error ("request for member %qE in something not a structure or union",
1611            component);
1612
1613   return error_mark_node;
1614 }
1615 \f
1616 /* Given an expression PTR for a pointer, return an expression
1617    for the value pointed to.
1618    ERRORSTRING is the name of the operator to appear in error messages.  */
1619
1620 tree
1621 build_indirect_ref (tree ptr, const char *errorstring)
1622 {
1623   tree pointer = default_conversion (ptr);
1624   tree type = TREE_TYPE (pointer);
1625
1626   if (TREE_CODE (type) == POINTER_TYPE)
1627     {
1628       if (TREE_CODE (pointer) == ADDR_EXPR
1629           && (TREE_TYPE (TREE_OPERAND (pointer, 0))
1630               == TREE_TYPE (type)))
1631         return TREE_OPERAND (pointer, 0);
1632       else
1633         {
1634           tree t = TREE_TYPE (type);
1635           tree mvt = t;
1636           tree ref;
1637
1638           if (TREE_CODE (mvt) != ARRAY_TYPE)
1639             mvt = TYPE_MAIN_VARIANT (mvt);
1640           ref = build1 (INDIRECT_REF, mvt, pointer);
1641
1642           if (!COMPLETE_OR_VOID_TYPE_P (t) && TREE_CODE (t) != ARRAY_TYPE)
1643             {
1644               error ("dereferencing pointer to incomplete type");
1645               return error_mark_node;
1646             }
1647           if (VOID_TYPE_P (t) && skip_evaluation == 0)
1648             warning ("dereferencing %<void *%> pointer");
1649
1650           /* We *must* set TREE_READONLY when dereferencing a pointer to const,
1651              so that we get the proper error message if the result is used
1652              to assign to.  Also, &* is supposed to be a no-op.
1653              And ANSI C seems to specify that the type of the result
1654              should be the const type.  */
1655           /* A de-reference of a pointer to const is not a const.  It is valid
1656              to change it via some other pointer.  */
1657           TREE_READONLY (ref) = TYPE_READONLY (t);
1658           TREE_SIDE_EFFECTS (ref)
1659             = TYPE_VOLATILE (t) || TREE_SIDE_EFFECTS (pointer);
1660           TREE_THIS_VOLATILE (ref) = TYPE_VOLATILE (t);
1661           return ref;
1662         }
1663     }
1664   else if (TREE_CODE (pointer) != ERROR_MARK)
1665     error ("invalid type argument of %qs", errorstring);
1666   return error_mark_node;
1667 }
1668
1669 /* This handles expressions of the form "a[i]", which denotes
1670    an array reference.
1671
1672    This is logically equivalent in C to *(a+i), but we may do it differently.
1673    If A is a variable or a member, we generate a primitive ARRAY_REF.
1674    This avoids forcing the array out of registers, and can work on
1675    arrays that are not lvalues (for example, members of structures returned
1676    by functions).  */
1677
1678 tree
1679 build_array_ref (tree array, tree index)
1680 {
1681   bool swapped = false;
1682   if (TREE_TYPE (array) == error_mark_node
1683       || TREE_TYPE (index) == error_mark_node)
1684     return error_mark_node;
1685
1686   if (TREE_CODE (TREE_TYPE (array)) != ARRAY_TYPE
1687       && TREE_CODE (TREE_TYPE (array)) != POINTER_TYPE)
1688     {
1689       tree temp;
1690       if (TREE_CODE (TREE_TYPE (index)) != ARRAY_TYPE
1691           && TREE_CODE (TREE_TYPE (index)) != POINTER_TYPE)
1692         {
1693           error ("subscripted value is neither array nor pointer");
1694           return error_mark_node;
1695         }
1696       temp = array;
1697       array = index;
1698       index = temp;
1699       swapped = true;
1700     }
1701
1702   if (!INTEGRAL_TYPE_P (TREE_TYPE (index)))
1703     {
1704       error ("array subscript is not an integer");
1705       return error_mark_node;
1706     }
1707
1708   if (TREE_CODE (TREE_TYPE (TREE_TYPE (array))) == FUNCTION_TYPE)
1709     {
1710       error ("subscripted value is pointer to function");
1711       return error_mark_node;
1712     }
1713
1714   /* Subscripting with type char is likely to lose on a machine where
1715      chars are signed.  So warn on any machine, but optionally.  Don't
1716      warn for unsigned char since that type is safe.  Don't warn for
1717      signed char because anyone who uses that must have done so
1718      deliberately.  ??? Existing practice has also been to warn only
1719      when the char index is syntactically the index, not for
1720      char[array].  */
1721   if (warn_char_subscripts && !swapped
1722       && TYPE_MAIN_VARIANT (TREE_TYPE (index)) == char_type_node)
1723     warning ("array subscript has type %<char%>");
1724
1725   /* Apply default promotions *after* noticing character types.  */
1726   index = default_conversion (index);
1727
1728   gcc_assert (TREE_CODE (TREE_TYPE (index)) == INTEGER_TYPE);
1729
1730   if (TREE_CODE (TREE_TYPE (array)) == ARRAY_TYPE)
1731     {
1732       tree rval, type;
1733
1734       /* An array that is indexed by a non-constant
1735          cannot be stored in a register; we must be able to do
1736          address arithmetic on its address.
1737          Likewise an array of elements of variable size.  */
1738       if (TREE_CODE (index) != INTEGER_CST
1739           || (COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (array)))
1740               && TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (array)))) != INTEGER_CST))
1741         {
1742           if (!c_mark_addressable (array))
1743             return error_mark_node;
1744         }
1745       /* An array that is indexed by a constant value which is not within
1746          the array bounds cannot be stored in a register either; because we
1747          would get a crash in store_bit_field/extract_bit_field when trying
1748          to access a non-existent part of the register.  */
1749       if (TREE_CODE (index) == INTEGER_CST
1750           && TYPE_DOMAIN (TREE_TYPE (array))
1751           && !int_fits_type_p (index, TYPE_DOMAIN (TREE_TYPE (array))))
1752         {
1753           if (!c_mark_addressable (array))
1754             return error_mark_node;
1755         }
1756
1757       if (pedantic)
1758         {
1759           tree foo = array;
1760           while (TREE_CODE (foo) == COMPONENT_REF)
1761             foo = TREE_OPERAND (foo, 0);
1762           if (TREE_CODE (foo) == VAR_DECL && C_DECL_REGISTER (foo))
1763             pedwarn ("ISO C forbids subscripting %<register%> array");
1764           else if (!flag_isoc99 && !lvalue_p (foo))
1765             pedwarn ("ISO C90 forbids subscripting non-lvalue array");
1766         }
1767
1768       type = TREE_TYPE (TREE_TYPE (array));
1769       if (TREE_CODE (type) != ARRAY_TYPE)
1770         type = TYPE_MAIN_VARIANT (type);
1771       rval = build4 (ARRAY_REF, type, array, index, NULL_TREE, NULL_TREE);
1772       /* Array ref is const/volatile if the array elements are
1773          or if the array is.  */
1774       TREE_READONLY (rval)
1775         |= (TYPE_READONLY (TREE_TYPE (TREE_TYPE (array)))
1776             | TREE_READONLY (array));
1777       TREE_SIDE_EFFECTS (rval)
1778         |= (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (array)))
1779             | TREE_SIDE_EFFECTS (array));
1780       TREE_THIS_VOLATILE (rval)
1781         |= (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (array)))
1782             /* This was added by rms on 16 Nov 91.
1783                It fixes  vol struct foo *a;  a->elts[1]
1784                in an inline function.
1785                Hope it doesn't break something else.  */
1786             | TREE_THIS_VOLATILE (array));
1787       return require_complete_type (fold (rval));
1788     }
1789   else
1790     {
1791       tree ar = default_conversion (array);
1792
1793       if (ar == error_mark_node)
1794         return ar;
1795
1796       gcc_assert (TREE_CODE (TREE_TYPE (ar)) == POINTER_TYPE);
1797       gcc_assert (TREE_CODE (TREE_TYPE (TREE_TYPE (ar))) != FUNCTION_TYPE);
1798
1799       return build_indirect_ref (build_binary_op (PLUS_EXPR, ar, index, 0),
1800                                  "array indexing");
1801     }
1802 }
1803 \f
1804 /* Build an external reference to identifier ID.  FUN indicates
1805    whether this will be used for a function call.  LOC is the source
1806    location of the identifier.  */
1807 tree
1808 build_external_ref (tree id, int fun, location_t loc)
1809 {
1810   tree ref;
1811   tree decl = lookup_name (id);
1812
1813   /* In Objective-C, an instance variable (ivar) may be preferred to
1814      whatever lookup_name() found.  */
1815   decl = objc_lookup_ivar (decl, id);
1816
1817   if (decl && decl != error_mark_node)
1818     ref = decl;
1819   else if (fun)
1820     /* Implicit function declaration.  */
1821     ref = implicitly_declare (id);
1822   else if (decl == error_mark_node)
1823     /* Don't complain about something that's already been
1824        complained about.  */
1825     return error_mark_node;
1826   else
1827     {
1828       undeclared_variable (id, loc);
1829       return error_mark_node;
1830     }
1831
1832   if (TREE_TYPE (ref) == error_mark_node)
1833     return error_mark_node;
1834
1835   if (TREE_DEPRECATED (ref))
1836     warn_deprecated_use (ref);
1837
1838   if (!skip_evaluation)
1839     assemble_external (ref);
1840   TREE_USED (ref) = 1;
1841
1842   if (TREE_CODE (ref) == FUNCTION_DECL && !in_alignof)
1843     {
1844       if (!in_sizeof && !in_typeof)
1845         C_DECL_USED (ref) = 1;
1846       else if (DECL_INITIAL (ref) == 0
1847                && DECL_EXTERNAL (ref)
1848                && !TREE_PUBLIC (ref))
1849         record_maybe_used_decl (ref);
1850     }
1851
1852   if (TREE_CODE (ref) == CONST_DECL)
1853     {
1854       ref = DECL_INITIAL (ref);
1855       TREE_CONSTANT (ref) = 1;
1856       TREE_INVARIANT (ref) = 1;
1857     }
1858   else if (current_function_decl != 0
1859            && !DECL_FILE_SCOPE_P (current_function_decl)
1860            && (TREE_CODE (ref) == VAR_DECL
1861                || TREE_CODE (ref) == PARM_DECL
1862                || TREE_CODE (ref) == FUNCTION_DECL))
1863     {
1864       tree context = decl_function_context (ref);
1865
1866       if (context != 0 && context != current_function_decl)
1867         DECL_NONLOCAL (ref) = 1;
1868     }
1869
1870   return ref;
1871 }
1872
1873 /* Record details of decls possibly used inside sizeof or typeof.  */
1874 struct maybe_used_decl
1875 {
1876   /* The decl.  */
1877   tree decl;
1878   /* The level seen at (in_sizeof + in_typeof).  */
1879   int level;
1880   /* The next one at this level or above, or NULL.  */
1881   struct maybe_used_decl *next;
1882 };
1883
1884 static struct maybe_used_decl *maybe_used_decls;
1885
1886 /* Record that DECL, an undefined static function reference seen
1887    inside sizeof or typeof, might be used if the operand of sizeof is
1888    a VLA type or the operand of typeof is a variably modified
1889    type.  */
1890
1891 static void
1892 record_maybe_used_decl (tree decl)
1893 {
1894   struct maybe_used_decl *t = XOBNEW (&parser_obstack, struct maybe_used_decl);
1895   t->decl = decl;
1896   t->level = in_sizeof + in_typeof;
1897   t->next = maybe_used_decls;
1898   maybe_used_decls = t;
1899 }
1900
1901 /* Pop the stack of decls possibly used inside sizeof or typeof.  If
1902    USED is false, just discard them.  If it is true, mark them used
1903    (if no longer inside sizeof or typeof) or move them to the next
1904    level up (if still inside sizeof or typeof).  */
1905
1906 void
1907 pop_maybe_used (bool used)
1908 {
1909   struct maybe_used_decl *p = maybe_used_decls;
1910   int cur_level = in_sizeof + in_typeof;
1911   while (p && p->level > cur_level)
1912     {
1913       if (used)
1914         {
1915           if (cur_level == 0)
1916             C_DECL_USED (p->decl) = 1;
1917           else
1918             p->level = cur_level;
1919         }
1920       p = p->next;
1921     }
1922   if (!used || cur_level == 0)
1923     maybe_used_decls = p;
1924 }
1925
1926 /* Return the result of sizeof applied to EXPR.  */
1927
1928 struct c_expr
1929 c_expr_sizeof_expr (struct c_expr expr)
1930 {
1931   struct c_expr ret;
1932   if (expr.value == error_mark_node)
1933     {
1934       ret.value = error_mark_node;
1935       ret.original_code = ERROR_MARK;
1936       pop_maybe_used (false);
1937     }
1938   else
1939     {
1940       ret.value = c_sizeof (TREE_TYPE (expr.value));
1941       ret.original_code = ERROR_MARK;
1942       pop_maybe_used (C_TYPE_VARIABLE_SIZE (TREE_TYPE (expr.value)));
1943     }
1944   return ret;
1945 }
1946
1947 /* Return the result of sizeof applied to T, a structure for the type
1948    name passed to sizeof (rather than the type itself).  */
1949
1950 struct c_expr
1951 c_expr_sizeof_type (struct c_type_name *t)
1952 {
1953   tree type;
1954   struct c_expr ret;
1955   type = groktypename (t);
1956   ret.value = c_sizeof (type);
1957   ret.original_code = ERROR_MARK;
1958   pop_maybe_used (C_TYPE_VARIABLE_SIZE (type));
1959   return ret;
1960 }
1961
1962 /* Build a function call to function FUNCTION with parameters PARAMS.
1963    PARAMS is a list--a chain of TREE_LIST nodes--in which the
1964    TREE_VALUE of each node is a parameter-expression.
1965    FUNCTION's data type may be a function type or a pointer-to-function.  */
1966
1967 tree
1968 build_function_call (tree function, tree params)
1969 {
1970   tree fntype, fundecl = 0;
1971   tree coerced_params;
1972   tree name = NULL_TREE, result;
1973   tree tem;
1974
1975   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
1976   STRIP_TYPE_NOPS (function);
1977
1978   /* Convert anything with function type to a pointer-to-function.  */
1979   if (TREE_CODE (function) == FUNCTION_DECL)
1980     {
1981       if (DECL_BUILT_IN_CLASS (function) == BUILT_IN_NORMAL)
1982         {
1983           tem = resolve_overloaded_builtin (function, params);
1984           if (tem)
1985             return tem;
1986         }
1987
1988       name = DECL_NAME (function);
1989
1990       /* Differs from default_conversion by not setting TREE_ADDRESSABLE
1991          (because calling an inline function does not mean the function
1992          needs to be separately compiled).  */
1993       fntype = build_type_variant (TREE_TYPE (function),
1994                                    TREE_READONLY (function),
1995                                    TREE_THIS_VOLATILE (function));
1996       fundecl = function;
1997       function = build1 (ADDR_EXPR, build_pointer_type (fntype), function);
1998     }
1999   else
2000     function = default_conversion (function);
2001
2002   fntype = TREE_TYPE (function);
2003
2004   if (TREE_CODE (fntype) == ERROR_MARK)
2005     return error_mark_node;
2006
2007   if (!(TREE_CODE (fntype) == POINTER_TYPE
2008         && TREE_CODE (TREE_TYPE (fntype)) == FUNCTION_TYPE))
2009     {
2010       error ("called object %qE is not a function", function);
2011       return error_mark_node;
2012     }
2013
2014   if (fundecl && TREE_THIS_VOLATILE (fundecl))
2015     current_function_returns_abnormally = 1;
2016
2017   /* fntype now gets the type of function pointed to.  */
2018   fntype = TREE_TYPE (fntype);
2019
2020   /* Check that the function is called through a compatible prototype.
2021      If it is not, replace the call by a trap, wrapped up in a compound
2022      expression if necessary.  This has the nice side-effect to prevent
2023      the tree-inliner from generating invalid assignment trees which may
2024      blow up in the RTL expander later.
2025
2026      ??? This doesn't work for Objective-C because objc_comptypes
2027      refuses to compare function prototypes, yet the compiler appears
2028      to build calls that are flagged as invalid by C's comptypes.  */
2029   if (!c_dialect_objc ()
2030       && TREE_CODE (function) == NOP_EXPR
2031       && TREE_CODE (tem = TREE_OPERAND (function, 0)) == ADDR_EXPR
2032       && TREE_CODE (tem = TREE_OPERAND (tem, 0)) == FUNCTION_DECL
2033       && !comptypes (fntype, TREE_TYPE (tem)))
2034     {
2035       tree return_type = TREE_TYPE (fntype);
2036       tree trap = build_function_call (built_in_decls[BUILT_IN_TRAP],
2037                                        NULL_TREE);
2038
2039       /* This situation leads to run-time undefined behavior.  We can't,
2040          therefore, simply error unless we can prove that all possible
2041          executions of the program must execute the code.  */
2042       warning ("function called through a non-compatible type");
2043
2044       /* We can, however, treat "undefined" any way we please.
2045          Call abort to encourage the user to fix the program.  */
2046       inform ("if this code is reached, the program will abort");
2047
2048       if (VOID_TYPE_P (return_type))
2049         return trap;
2050       else
2051         {
2052           tree rhs;
2053
2054           if (AGGREGATE_TYPE_P (return_type))
2055             rhs = build_compound_literal (return_type,
2056                                           build_constructor (return_type,
2057                                                              NULL_TREE));
2058           else
2059             rhs = fold (build1 (NOP_EXPR, return_type, integer_zero_node));
2060
2061           return build2 (COMPOUND_EXPR, return_type, trap, rhs);
2062         }
2063     }
2064
2065   /* Convert the parameters to the types declared in the
2066      function prototype, or apply default promotions.  */
2067
2068   coerced_params
2069     = convert_arguments (TYPE_ARG_TYPES (fntype), params, function, fundecl);
2070
2071   if (coerced_params == error_mark_node)
2072     return error_mark_node;
2073
2074   /* Check that the arguments to the function are valid.  */
2075
2076   check_function_arguments (TYPE_ATTRIBUTES (fntype), coerced_params);
2077
2078   result = build3 (CALL_EXPR, TREE_TYPE (fntype),
2079                    function, coerced_params, NULL_TREE);
2080   TREE_SIDE_EFFECTS (result) = 1;
2081
2082   if (require_constant_value)
2083     {
2084       result = fold_initializer (result);
2085
2086       if (TREE_CONSTANT (result)
2087           && (name == NULL_TREE
2088               || strncmp (IDENTIFIER_POINTER (name), "__builtin_", 10) != 0))
2089         pedwarn_init ("initializer element is not constant");
2090     }
2091   else
2092     result = fold (result);
2093
2094   if (VOID_TYPE_P (TREE_TYPE (result)))
2095     return result;
2096   return require_complete_type (result);
2097 }
2098 \f
2099 /* Convert the argument expressions in the list VALUES
2100    to the types in the list TYPELIST.  The result is a list of converted
2101    argument expressions, unless there are too few arguments in which
2102    case it is error_mark_node.
2103
2104    If TYPELIST is exhausted, or when an element has NULL as its type,
2105    perform the default conversions.
2106
2107    PARMLIST is the chain of parm decls for the function being called.
2108    It may be 0, if that info is not available.
2109    It is used only for generating error messages.
2110
2111    FUNCTION is a tree for the called function.  It is used only for
2112    error messages, where it is formatted with %qE.
2113
2114    This is also where warnings about wrong number of args are generated.
2115
2116    Both VALUES and the returned value are chains of TREE_LIST nodes
2117    with the elements of the list in the TREE_VALUE slots of those nodes.  */
2118
2119 static tree
2120 convert_arguments (tree typelist, tree values, tree function, tree fundecl)
2121 {
2122   tree typetail, valtail;
2123   tree result = NULL;
2124   int parmnum;
2125   tree selector;
2126
2127   /* Change pointer to function to the function itself for
2128      diagnostics.  */
2129   if (TREE_CODE (function) == ADDR_EXPR
2130       && TREE_CODE (TREE_OPERAND (function, 0)) == FUNCTION_DECL)
2131     function = TREE_OPERAND (function, 0);
2132
2133   /* Handle an ObjC selector specially for diagnostics.  */
2134   selector = objc_message_selector ();
2135
2136   /* Scan the given expressions and types, producing individual
2137      converted arguments and pushing them on RESULT in reverse order.  */
2138
2139   for (valtail = values, typetail = typelist, parmnum = 0;
2140        valtail;
2141        valtail = TREE_CHAIN (valtail), parmnum++)
2142     {
2143       tree type = typetail ? TREE_VALUE (typetail) : 0;
2144       tree val = TREE_VALUE (valtail);
2145       tree rname = function;
2146       int argnum = parmnum + 1;
2147       const char *invalid_func_diag;
2148
2149       if (type == void_type_node)
2150         {
2151           error ("too many arguments to function %qE", function);
2152           break;
2153         }
2154
2155       if (selector && argnum > 2)
2156         {
2157           rname = selector;
2158           argnum -= 2;
2159         }
2160
2161       STRIP_TYPE_NOPS (val);
2162
2163       val = default_function_array_conversion (val);
2164
2165       val = require_complete_type (val);
2166
2167       if (type != 0)
2168         {
2169           /* Formal parm type is specified by a function prototype.  */
2170           tree parmval;
2171
2172           if (type == error_mark_node || !COMPLETE_TYPE_P (type))
2173             {
2174               error ("type of formal parameter %d is incomplete", parmnum + 1);
2175               parmval = val;
2176             }
2177           else
2178             {
2179               /* Optionally warn about conversions that
2180                  differ from the default conversions.  */
2181               if (warn_conversion || warn_traditional)
2182                 {
2183                   unsigned int formal_prec = TYPE_PRECISION (type);
2184
2185                   if (INTEGRAL_TYPE_P (type)
2186                       && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
2187                     warning ("passing argument %d of %qE as integer "
2188                              "rather than floating due to prototype",
2189                              argnum, rname);
2190                   if (INTEGRAL_TYPE_P (type)
2191                       && TREE_CODE (TREE_TYPE (val)) == COMPLEX_TYPE)
2192                     warning ("passing argument %d of %qE as integer "
2193                              "rather than complex due to prototype",
2194                              argnum, rname);
2195                   else if (TREE_CODE (type) == COMPLEX_TYPE
2196                            && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
2197                     warning ("passing argument %d of %qE as complex "
2198                              "rather than floating due to prototype",
2199                              argnum, rname);
2200                   else if (TREE_CODE (type) == REAL_TYPE
2201                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2202                     warning ("passing argument %d of %qE as floating "
2203                              "rather than integer due to prototype",
2204                              argnum, rname);
2205                   else if (TREE_CODE (type) == COMPLEX_TYPE
2206                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2207                     warning ("passing argument %d of %qE as complex "
2208                              "rather than integer due to prototype",
2209                              argnum, rname);
2210                   else if (TREE_CODE (type) == REAL_TYPE
2211                            && TREE_CODE (TREE_TYPE (val)) == COMPLEX_TYPE)
2212                     warning ("passing argument %d of %qE as floating "
2213                              "rather than complex due to prototype",
2214                              argnum, rname);
2215                   /* ??? At some point, messages should be written about
2216                      conversions between complex types, but that's too messy
2217                      to do now.  */
2218                   else if (TREE_CODE (type) == REAL_TYPE
2219                            && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
2220                     {
2221                       /* Warn if any argument is passed as `float',
2222                          since without a prototype it would be `double'.  */
2223                       if (formal_prec == TYPE_PRECISION (float_type_node))
2224                         warning ("passing argument %d of %qE as %<float%> "
2225                                  "rather than %<double%> due to prototype",
2226                                  argnum, rname);
2227                     }
2228                   /* Detect integer changing in width or signedness.
2229                      These warnings are only activated with
2230                      -Wconversion, not with -Wtraditional.  */
2231                   else if (warn_conversion && INTEGRAL_TYPE_P (type)
2232                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2233                     {
2234                       tree would_have_been = default_conversion (val);
2235                       tree type1 = TREE_TYPE (would_have_been);
2236
2237                       if (TREE_CODE (type) == ENUMERAL_TYPE
2238                           && (TYPE_MAIN_VARIANT (type)
2239                               == TYPE_MAIN_VARIANT (TREE_TYPE (val))))
2240                         /* No warning if function asks for enum
2241                            and the actual arg is that enum type.  */
2242                         ;
2243                       else if (formal_prec != TYPE_PRECISION (type1))
2244                         warning ("passing argument %d of %qE with different "
2245                                  "width due to prototype", argnum, rname);
2246                       else if (TYPE_UNSIGNED (type) == TYPE_UNSIGNED (type1))
2247                         ;
2248                       /* Don't complain if the formal parameter type
2249                          is an enum, because we can't tell now whether
2250                          the value was an enum--even the same enum.  */
2251                       else if (TREE_CODE (type) == ENUMERAL_TYPE)
2252                         ;
2253                       else if (TREE_CODE (val) == INTEGER_CST
2254                                && int_fits_type_p (val, type))
2255                         /* Change in signedness doesn't matter
2256                            if a constant value is unaffected.  */
2257                         ;
2258                       /* If the value is extended from a narrower
2259                          unsigned type, it doesn't matter whether we
2260                          pass it as signed or unsigned; the value
2261                          certainly is the same either way.  */
2262                       else if (TYPE_PRECISION (TREE_TYPE (val)) < TYPE_PRECISION (type)
2263                                && TYPE_UNSIGNED (TREE_TYPE (val)))
2264                         ;
2265                       else if (TYPE_UNSIGNED (type))
2266                         warning ("passing argument %d of %qE as unsigned "
2267                                  "due to prototype", argnum, rname);
2268                       else
2269                         warning ("passing argument %d of %qE as signed "
2270                                  "due to prototype", argnum, rname);
2271                     }
2272                 }
2273
2274               parmval = convert_for_assignment (type, val, ic_argpass,
2275                                                 fundecl, function,
2276                                                 parmnum + 1);
2277
2278               if (targetm.calls.promote_prototypes (fundecl ? TREE_TYPE (fundecl) : 0)
2279                   && INTEGRAL_TYPE_P (type)
2280                   && (TYPE_PRECISION (type) < TYPE_PRECISION (integer_type_node)))
2281                 parmval = default_conversion (parmval);
2282             }
2283           result = tree_cons (NULL_TREE, parmval, result);
2284         }
2285       else if (TREE_CODE (TREE_TYPE (val)) == REAL_TYPE
2286                && (TYPE_PRECISION (TREE_TYPE (val))
2287                    < TYPE_PRECISION (double_type_node)))
2288         /* Convert `float' to `double'.  */
2289         result = tree_cons (NULL_TREE, convert (double_type_node, val), result);
2290       else if ((invalid_func_diag =
2291                 targetm.calls.invalid_arg_for_unprototyped_fn (typelist, fundecl, val)))
2292         {
2293           error (invalid_func_diag);
2294           return error_mark_node;
2295         }
2296       else
2297         /* Convert `short' and `char' to full-size `int'.  */
2298         result = tree_cons (NULL_TREE, default_conversion (val), result);
2299
2300       if (typetail)
2301         typetail = TREE_CHAIN (typetail);
2302     }
2303
2304   if (typetail != 0 && TREE_VALUE (typetail) != void_type_node)
2305     {
2306       error ("too few arguments to function %qE", function);
2307       return error_mark_node;
2308     }
2309
2310   return nreverse (result);
2311 }
2312 \f
2313 /* This is the entry point used by the parser
2314    for binary operators in the input.
2315    In addition to constructing the expression,
2316    we check for operands that were written with other binary operators
2317    in a way that is likely to confuse the user.  */
2318
2319 struct c_expr
2320 parser_build_binary_op (enum tree_code code, struct c_expr arg1,
2321                         struct c_expr arg2)
2322 {
2323   struct c_expr result;
2324
2325   enum tree_code code1 = arg1.original_code;
2326   enum tree_code code2 = arg2.original_code;
2327
2328   result.value = build_binary_op (code, arg1.value, arg2.value, 1);
2329   result.original_code = code;
2330
2331   if (TREE_CODE (result.value) == ERROR_MARK)
2332     return result;
2333
2334   /* Check for cases such as x+y<<z which users are likely
2335      to misinterpret.  */
2336   if (warn_parentheses)
2337     {
2338       if (code == LSHIFT_EXPR || code == RSHIFT_EXPR)
2339         {
2340           if (code1 == PLUS_EXPR || code1 == MINUS_EXPR
2341               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2342             warning ("suggest parentheses around + or - inside shift");
2343         }
2344
2345       if (code == TRUTH_ORIF_EXPR)
2346         {
2347           if (code1 == TRUTH_ANDIF_EXPR
2348               || code2 == TRUTH_ANDIF_EXPR)
2349             warning ("suggest parentheses around && within ||");
2350         }
2351
2352       if (code == BIT_IOR_EXPR)
2353         {
2354           if (code1 == BIT_AND_EXPR || code1 == BIT_XOR_EXPR
2355               || code1 == PLUS_EXPR || code1 == MINUS_EXPR
2356               || code2 == BIT_AND_EXPR || code2 == BIT_XOR_EXPR
2357               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2358             warning ("suggest parentheses around arithmetic in operand of |");
2359           /* Check cases like x|y==z */
2360           if (TREE_CODE_CLASS (code1) == tcc_comparison
2361               || TREE_CODE_CLASS (code2) == tcc_comparison)
2362             warning ("suggest parentheses around comparison in operand of |");
2363         }
2364
2365       if (code == BIT_XOR_EXPR)
2366         {
2367           if (code1 == BIT_AND_EXPR
2368               || code1 == PLUS_EXPR || code1 == MINUS_EXPR
2369               || code2 == BIT_AND_EXPR
2370               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2371             warning ("suggest parentheses around arithmetic in operand of ^");
2372           /* Check cases like x^y==z */
2373           if (TREE_CODE_CLASS (code1) == tcc_comparison
2374               || TREE_CODE_CLASS (code2) == tcc_comparison)
2375             warning ("suggest parentheses around comparison in operand of ^");
2376         }
2377
2378       if (code == BIT_AND_EXPR)
2379         {
2380           if (code1 == PLUS_EXPR || code1 == MINUS_EXPR
2381               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2382             warning ("suggest parentheses around + or - in operand of &");
2383           /* Check cases like x&y==z */
2384           if (TREE_CODE_CLASS (code1) == tcc_comparison
2385               || TREE_CODE_CLASS (code2) == tcc_comparison)
2386             warning ("suggest parentheses around comparison in operand of &");
2387         }
2388       /* Similarly, check for cases like 1<=i<=10 that are probably errors.  */
2389       if (TREE_CODE_CLASS (code) == tcc_comparison
2390           && (TREE_CODE_CLASS (code1) == tcc_comparison
2391               || TREE_CODE_CLASS (code2) == tcc_comparison))
2392         warning ("comparisons like X<=Y<=Z do not have their mathematical meaning");
2393
2394     }
2395
2396   unsigned_conversion_warning (result.value, arg1.value);
2397   unsigned_conversion_warning (result.value, arg2.value);
2398   overflow_warning (result.value);
2399
2400   return result;
2401 }
2402 \f
2403 /* Return a tree for the difference of pointers OP0 and OP1.
2404    The resulting tree has type int.  */
2405
2406 static tree
2407 pointer_diff (tree op0, tree op1)
2408 {
2409   tree restype = ptrdiff_type_node;
2410
2411   tree target_type = TREE_TYPE (TREE_TYPE (op0));
2412   tree con0, con1, lit0, lit1;
2413   tree orig_op1 = op1;
2414
2415   if (pedantic || warn_pointer_arith)
2416     {
2417       if (TREE_CODE (target_type) == VOID_TYPE)
2418         pedwarn ("pointer of type %<void *%> used in subtraction");
2419       if (TREE_CODE (target_type) == FUNCTION_TYPE)
2420         pedwarn ("pointer to a function used in subtraction");
2421     }
2422
2423   /* If the conversion to ptrdiff_type does anything like widening or
2424      converting a partial to an integral mode, we get a convert_expression
2425      that is in the way to do any simplifications.
2426      (fold-const.c doesn't know that the extra bits won't be needed.
2427      split_tree uses STRIP_SIGN_NOPS, which leaves conversions to a
2428      different mode in place.)
2429      So first try to find a common term here 'by hand'; we want to cover
2430      at least the cases that occur in legal static initializers.  */
2431   con0 = TREE_CODE (op0) == NOP_EXPR ? TREE_OPERAND (op0, 0) : op0;
2432   con1 = TREE_CODE (op1) == NOP_EXPR ? TREE_OPERAND (op1, 0) : op1;
2433
2434   if (TREE_CODE (con0) == PLUS_EXPR)
2435     {
2436       lit0 = TREE_OPERAND (con0, 1);
2437       con0 = TREE_OPERAND (con0, 0);
2438     }
2439   else
2440     lit0 = integer_zero_node;
2441
2442   if (TREE_CODE (con1) == PLUS_EXPR)
2443     {
2444       lit1 = TREE_OPERAND (con1, 1);
2445       con1 = TREE_OPERAND (con1, 0);
2446     }
2447   else
2448     lit1 = integer_zero_node;
2449
2450   if (operand_equal_p (con0, con1, 0))
2451     {
2452       op0 = lit0;
2453       op1 = lit1;
2454     }
2455
2456
2457   /* First do the subtraction as integers;
2458      then drop through to build the divide operator.
2459      Do not do default conversions on the minus operator
2460      in case restype is a short type.  */
2461
2462   op0 = build_binary_op (MINUS_EXPR, convert (restype, op0),
2463                          convert (restype, op1), 0);
2464   /* This generates an error if op1 is pointer to incomplete type.  */
2465   if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (TREE_TYPE (orig_op1))))
2466     error ("arithmetic on pointer to an incomplete type");
2467
2468   /* This generates an error if op0 is pointer to incomplete type.  */
2469   op1 = c_size_in_bytes (target_type);
2470
2471   /* Divide by the size, in easiest possible way.  */
2472   return fold (build2 (EXACT_DIV_EXPR, restype, op0, convert (restype, op1)));
2473 }
2474 \f
2475 /* Construct and perhaps optimize a tree representation
2476    for a unary operation.  CODE, a tree_code, specifies the operation
2477    and XARG is the operand.
2478    For any CODE other than ADDR_EXPR, FLAG nonzero suppresses
2479    the default promotions (such as from short to int).
2480    For ADDR_EXPR, the default promotions are not applied; FLAG nonzero
2481    allows non-lvalues; this is only used to handle conversion of non-lvalue
2482    arrays to pointers in C99.  */
2483
2484 tree
2485 build_unary_op (enum tree_code code, tree xarg, int flag)
2486 {
2487   /* No default_conversion here.  It causes trouble for ADDR_EXPR.  */
2488   tree arg = xarg;
2489   tree argtype = 0;
2490   enum tree_code typecode = TREE_CODE (TREE_TYPE (arg));
2491   tree val;
2492   int noconvert = flag;
2493
2494   if (typecode == ERROR_MARK)
2495     return error_mark_node;
2496   if (typecode == ENUMERAL_TYPE || typecode == BOOLEAN_TYPE)
2497     typecode = INTEGER_TYPE;
2498
2499   switch (code)
2500     {
2501     case CONVERT_EXPR:
2502       /* This is used for unary plus, because a CONVERT_EXPR
2503          is enough to prevent anybody from looking inside for
2504          associativity, but won't generate any code.  */
2505       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2506             || typecode == COMPLEX_TYPE
2507             || typecode == VECTOR_TYPE))
2508         {
2509           error ("wrong type argument to unary plus");
2510           return error_mark_node;
2511         }
2512       else if (!noconvert)
2513         arg = default_conversion (arg);
2514       arg = non_lvalue (arg);
2515       break;
2516
2517     case NEGATE_EXPR:
2518       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2519             || typecode == COMPLEX_TYPE
2520             || typecode == VECTOR_TYPE))
2521         {
2522           error ("wrong type argument to unary minus");
2523           return error_mark_node;
2524         }
2525       else if (!noconvert)
2526         arg = default_conversion (arg);
2527       break;
2528
2529     case BIT_NOT_EXPR:
2530       if (typecode == INTEGER_TYPE || typecode == VECTOR_TYPE)
2531         {
2532           if (!noconvert)
2533             arg = default_conversion (arg);
2534         }
2535       else if (typecode == COMPLEX_TYPE)
2536         {
2537           code = CONJ_EXPR;
2538           if (pedantic)
2539             pedwarn ("ISO C does not support %<~%> for complex conjugation");
2540           if (!noconvert)
2541             arg = default_conversion (arg);
2542         }
2543       else
2544         {
2545           error ("wrong type argument to bit-complement");
2546           return error_mark_node;
2547         }
2548       break;
2549
2550     case ABS_EXPR:
2551       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE))
2552         {
2553           error ("wrong type argument to abs");
2554           return error_mark_node;
2555         }
2556       else if (!noconvert)
2557         arg = default_conversion (arg);
2558       break;
2559
2560     case CONJ_EXPR:
2561       /* Conjugating a real value is a no-op, but allow it anyway.  */
2562       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2563             || typecode == COMPLEX_TYPE))
2564         {
2565           error ("wrong type argument to conjugation");
2566           return error_mark_node;
2567         }
2568       else if (!noconvert)
2569         arg = default_conversion (arg);
2570       break;
2571
2572     case TRUTH_NOT_EXPR:
2573       /* ??? Why do most validation here but that for non-lvalue arrays
2574          in c_objc_common_truthvalue_conversion?  */
2575       if (typecode != INTEGER_TYPE
2576           && typecode != REAL_TYPE && typecode != POINTER_TYPE
2577           && typecode != COMPLEX_TYPE
2578           /* These will convert to a pointer.  */
2579           && typecode != ARRAY_TYPE && typecode != FUNCTION_TYPE)
2580         {
2581           error ("wrong type argument to unary exclamation mark");
2582           return error_mark_node;
2583         }
2584       arg = c_objc_common_truthvalue_conversion (arg);
2585       return invert_truthvalue (arg);
2586
2587     case NOP_EXPR:
2588       break;
2589
2590     case REALPART_EXPR:
2591       if (TREE_CODE (arg) == COMPLEX_CST)
2592         return TREE_REALPART (arg);
2593       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
2594         return fold (build1 (REALPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg));
2595       else
2596         return arg;
2597
2598     case IMAGPART_EXPR:
2599       if (TREE_CODE (arg) == COMPLEX_CST)
2600         return TREE_IMAGPART (arg);
2601       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
2602         return fold (build1 (IMAGPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg));
2603       else
2604         return convert (TREE_TYPE (arg), integer_zero_node);
2605
2606     case PREINCREMENT_EXPR:
2607     case POSTINCREMENT_EXPR:
2608     case PREDECREMENT_EXPR:
2609     case POSTDECREMENT_EXPR:
2610
2611       /* Increment or decrement the real part of the value,
2612          and don't change the imaginary part.  */
2613       if (typecode == COMPLEX_TYPE)
2614         {
2615           tree real, imag;
2616
2617           if (pedantic)
2618             pedwarn ("ISO C does not support %<++%> and %<--%>"
2619                      " on complex types");
2620
2621           arg = stabilize_reference (arg);
2622           real = build_unary_op (REALPART_EXPR, arg, 1);
2623           imag = build_unary_op (IMAGPART_EXPR, arg, 1);
2624           return build2 (COMPLEX_EXPR, TREE_TYPE (arg),
2625                          build_unary_op (code, real, 1), imag);
2626         }
2627
2628       /* Report invalid types.  */
2629
2630       if (typecode != POINTER_TYPE
2631           && typecode != INTEGER_TYPE && typecode != REAL_TYPE)
2632         {
2633           if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
2634             error ("wrong type argument to increment");
2635           else
2636             error ("wrong type argument to decrement");
2637
2638           return error_mark_node;
2639         }
2640
2641       {
2642         tree inc;
2643         tree result_type = TREE_TYPE (arg);
2644
2645         arg = get_unwidened (arg, 0);
2646         argtype = TREE_TYPE (arg);
2647
2648         /* Compute the increment.  */
2649
2650         if (typecode == POINTER_TYPE)
2651           {
2652             /* If pointer target is an undefined struct,
2653                we just cannot know how to do the arithmetic.  */
2654             if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (result_type)))
2655               {
2656                 if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
2657                   error ("increment of pointer to unknown structure");
2658                 else
2659                   error ("decrement of pointer to unknown structure");
2660               }
2661             else if ((pedantic || warn_pointer_arith)
2662                      && (TREE_CODE (TREE_TYPE (result_type)) == FUNCTION_TYPE
2663                          || TREE_CODE (TREE_TYPE (result_type)) == VOID_TYPE))
2664               {
2665                 if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
2666                   pedwarn ("wrong type argument to increment");
2667                 else
2668                   pedwarn ("wrong type argument to decrement");
2669               }
2670
2671             inc = c_size_in_bytes (TREE_TYPE (result_type));
2672           }
2673         else
2674           inc = integer_one_node;
2675
2676         inc = convert (argtype, inc);
2677
2678         /* Complain about anything else that is not a true lvalue.  */
2679         if (!lvalue_or_else (arg, ((code == PREINCREMENT_EXPR
2680                                     || code == POSTINCREMENT_EXPR)
2681                                    ? lv_increment
2682                                    : lv_decrement)))
2683           return error_mark_node;
2684
2685         /* Report a read-only lvalue.  */
2686         if (TREE_READONLY (arg))
2687           readonly_error (arg,
2688                           ((code == PREINCREMENT_EXPR
2689                             || code == POSTINCREMENT_EXPR)
2690                            ? lv_increment : lv_decrement));
2691
2692         if (TREE_CODE (TREE_TYPE (arg)) == BOOLEAN_TYPE)
2693           val = boolean_increment (code, arg);
2694         else
2695           val = build2 (code, TREE_TYPE (arg), arg, inc);
2696         TREE_SIDE_EFFECTS (val) = 1;
2697         val = convert (result_type, val);
2698         if (TREE_CODE (val) != code)
2699           TREE_NO_WARNING (val) = 1;
2700         return val;
2701       }
2702
2703     case ADDR_EXPR:
2704       /* Note that this operation never does default_conversion.  */
2705
2706       /* Let &* cancel out to simplify resulting code.  */
2707       if (TREE_CODE (arg) == INDIRECT_REF)
2708         {
2709           /* Don't let this be an lvalue.  */
2710           if (lvalue_p (TREE_OPERAND (arg, 0)))
2711             return non_lvalue (TREE_OPERAND (arg, 0));
2712           return TREE_OPERAND (arg, 0);
2713         }
2714
2715       /* For &x[y], return x+y */
2716       if (TREE_CODE (arg) == ARRAY_REF)
2717         {
2718           if (!c_mark_addressable (TREE_OPERAND (arg, 0)))
2719             return error_mark_node;
2720           return build_binary_op (PLUS_EXPR, TREE_OPERAND (arg, 0),
2721                                   TREE_OPERAND (arg, 1), 1);
2722         }
2723
2724       /* Anything not already handled and not a true memory reference
2725          or a non-lvalue array is an error.  */
2726       else if (typecode != FUNCTION_TYPE && !flag
2727                && !lvalue_or_else (arg, lv_addressof))
2728         return error_mark_node;
2729
2730       /* Ordinary case; arg is a COMPONENT_REF or a decl.  */
2731       argtype = TREE_TYPE (arg);
2732
2733       /* If the lvalue is const or volatile, merge that into the type
2734          to which the address will point.  Note that you can't get a
2735          restricted pointer by taking the address of something, so we
2736          only have to deal with `const' and `volatile' here.  */
2737       if ((DECL_P (arg) || REFERENCE_CLASS_P (arg))
2738           && (TREE_READONLY (arg) || TREE_THIS_VOLATILE (arg)))
2739           argtype = c_build_type_variant (argtype,
2740                                           TREE_READONLY (arg),
2741                                           TREE_THIS_VOLATILE (arg));
2742
2743       if (!c_mark_addressable (arg))
2744         return error_mark_node;
2745
2746       gcc_assert (TREE_CODE (arg) != COMPONENT_REF
2747                   || !DECL_C_BIT_FIELD (TREE_OPERAND (arg, 1)));
2748
2749       argtype = build_pointer_type (argtype);
2750
2751       /* ??? Cope with user tricks that amount to offsetof.  Delete this
2752          when we have proper support for integer constant expressions.  */
2753       val = get_base_address (arg);
2754       if (val && TREE_CODE (val) == INDIRECT_REF
2755           && integer_zerop (TREE_OPERAND (val, 0)))
2756         return fold_convert (argtype, fold_offsetof (arg));
2757
2758       val = build1 (ADDR_EXPR, argtype, arg);
2759
2760       if (TREE_CODE (arg) == COMPOUND_LITERAL_EXPR)
2761         TREE_INVARIANT (val) = TREE_CONSTANT (val) = 1;
2762
2763       return val;
2764
2765     default:
2766       break;
2767     }
2768
2769   if (argtype == 0)
2770     argtype = TREE_TYPE (arg);
2771   val = build1 (code, argtype, arg);
2772   return require_constant_value ? fold_initializer (val) : fold (val);
2773 }
2774
2775 /* Return nonzero if REF is an lvalue valid for this language.
2776    Lvalues can be assigned, unless their type has TYPE_READONLY.
2777    Lvalues can have their address taken, unless they have C_DECL_REGISTER.  */
2778
2779 static int
2780 lvalue_p (tree ref)
2781 {
2782   enum tree_code code = TREE_CODE (ref);
2783
2784   switch (code)
2785     {
2786     case REALPART_EXPR:
2787     case IMAGPART_EXPR:
2788     case COMPONENT_REF:
2789       return lvalue_p (TREE_OPERAND (ref, 0));
2790
2791     case COMPOUND_LITERAL_EXPR:
2792     case STRING_CST:
2793       return 1;
2794
2795     case INDIRECT_REF:
2796     case ARRAY_REF:
2797     case VAR_DECL:
2798     case PARM_DECL:
2799     case RESULT_DECL:
2800     case ERROR_MARK:
2801       return (TREE_CODE (TREE_TYPE (ref)) != FUNCTION_TYPE
2802               && TREE_CODE (TREE_TYPE (ref)) != METHOD_TYPE);
2803
2804     case BIND_EXPR:
2805       return TREE_CODE (TREE_TYPE (ref)) == ARRAY_TYPE;
2806
2807     default:
2808       return 0;
2809     }
2810 }
2811 \f
2812 /* Give an error for storing in something that is 'const'.  */
2813
2814 static void
2815 readonly_error (tree arg, enum lvalue_use use)
2816 {
2817   gcc_assert (use == lv_assign || use == lv_increment || use == lv_decrement);
2818   /* Using this macro rather than (for example) arrays of messages
2819      ensures that all the format strings are checked at compile
2820      time.  */
2821 #define READONLY_MSG(A, I, D) (use == lv_assign                         \
2822                                ? (A)                                    \
2823                                : (use == lv_increment ? (I) : (D)))
2824   if (TREE_CODE (arg) == COMPONENT_REF)
2825     {
2826       if (TYPE_READONLY (TREE_TYPE (TREE_OPERAND (arg, 0))))
2827         readonly_error (TREE_OPERAND (arg, 0), use);
2828       else
2829         error (READONLY_MSG (N_("assignment of read-only member %qD"),
2830                              N_("increment of read-only member %qD"),
2831                              N_("decrement of read-only member %qD")),
2832                TREE_OPERAND (arg, 1));
2833     }
2834   else if (TREE_CODE (arg) == VAR_DECL)
2835     error (READONLY_MSG (N_("assignment of read-only variable %qD"),
2836                          N_("increment of read-only variable %qD"),
2837                          N_("decrement of read-only variable %qD")),
2838            arg);
2839   else
2840     error (READONLY_MSG (N_("assignment of read-only location"),
2841                          N_("increment of read-only location"),
2842                          N_("decrement of read-only location")));
2843 }
2844
2845
2846 /* Return nonzero if REF is an lvalue valid for this language;
2847    otherwise, print an error message and return zero.  USE says
2848    how the lvalue is being used and so selects the error message.  */
2849
2850 static int
2851 lvalue_or_else (tree ref, enum lvalue_use use)
2852 {
2853   int win = lvalue_p (ref);
2854
2855   if (!win)
2856     lvalue_error (use);
2857
2858   return win;
2859 }
2860 \f
2861 /* Mark EXP saying that we need to be able to take the
2862    address of it; it should not be allocated in a register.
2863    Returns true if successful.  */
2864
2865 bool
2866 c_mark_addressable (tree exp)
2867 {
2868   tree x = exp;
2869
2870   while (1)
2871     switch (TREE_CODE (x))
2872       {
2873       case COMPONENT_REF:
2874         if (DECL_C_BIT_FIELD (TREE_OPERAND (x, 1)))
2875           {
2876             error
2877               ("cannot take address of bit-field %qD", TREE_OPERAND (x, 1));
2878             return false;
2879           }
2880
2881         /* ... fall through ...  */
2882
2883       case ADDR_EXPR:
2884       case ARRAY_REF:
2885       case REALPART_EXPR:
2886       case IMAGPART_EXPR:
2887         x = TREE_OPERAND (x, 0);
2888         break;
2889
2890       case COMPOUND_LITERAL_EXPR:
2891       case CONSTRUCTOR:
2892         TREE_ADDRESSABLE (x) = 1;
2893         return true;
2894
2895       case VAR_DECL:
2896       case CONST_DECL:
2897       case PARM_DECL:
2898       case RESULT_DECL:
2899         if (C_DECL_REGISTER (x)
2900             && DECL_NONLOCAL (x))
2901           {
2902             if (TREE_PUBLIC (x) || TREE_STATIC (x) || DECL_EXTERNAL (x))
2903               {
2904                 error
2905                   ("global register variable %qD used in nested function", x);
2906                 return false;
2907               }
2908             pedwarn ("register variable %qD used in nested function", x);
2909           }
2910         else if (C_DECL_REGISTER (x))
2911           {
2912             if (TREE_PUBLIC (x) || TREE_STATIC (x) || DECL_EXTERNAL (x))
2913               error ("address of global register variable %qD requested", x);
2914             else
2915               error ("address of register variable %qD requested", x);
2916             return false;
2917           }
2918
2919         /* drops in */
2920       case FUNCTION_DECL:
2921         TREE_ADDRESSABLE (x) = 1;
2922         /* drops out */
2923       default:
2924         return true;
2925     }
2926 }
2927 \f
2928 /* Build and return a conditional expression IFEXP ? OP1 : OP2.  */
2929
2930 tree
2931 build_conditional_expr (tree ifexp, tree op1, tree op2)
2932 {
2933   tree type1;
2934   tree type2;
2935   enum tree_code code1;
2936   enum tree_code code2;
2937   tree result_type = NULL;
2938   tree orig_op1 = op1, orig_op2 = op2;
2939
2940   /* Promote both alternatives.  */
2941
2942   if (TREE_CODE (TREE_TYPE (op1)) != VOID_TYPE)
2943     op1 = default_conversion (op1);
2944   if (TREE_CODE (TREE_TYPE (op2)) != VOID_TYPE)
2945     op2 = default_conversion (op2);
2946
2947   if (TREE_CODE (ifexp) == ERROR_MARK
2948       || TREE_CODE (TREE_TYPE (op1)) == ERROR_MARK
2949       || TREE_CODE (TREE_TYPE (op2)) == ERROR_MARK)
2950     return error_mark_node;
2951
2952   type1 = TREE_TYPE (op1);
2953   code1 = TREE_CODE (type1);
2954   type2 = TREE_TYPE (op2);
2955   code2 = TREE_CODE (type2);
2956
2957   /* C90 does not permit non-lvalue arrays in conditional expressions.
2958      In C99 they will be pointers by now.  */
2959   if (code1 == ARRAY_TYPE || code2 == ARRAY_TYPE)
2960     {
2961       error ("non-lvalue array in conditional expression");
2962       return error_mark_node;
2963     }
2964
2965   /* Quickly detect the usual case where op1 and op2 have the same type
2966      after promotion.  */
2967   if (TYPE_MAIN_VARIANT (type1) == TYPE_MAIN_VARIANT (type2))
2968     {
2969       if (type1 == type2)
2970         result_type = type1;
2971       else
2972         result_type = TYPE_MAIN_VARIANT (type1);
2973     }
2974   else if ((code1 == INTEGER_TYPE || code1 == REAL_TYPE
2975             || code1 == COMPLEX_TYPE)
2976            && (code2 == INTEGER_TYPE || code2 == REAL_TYPE
2977                || code2 == COMPLEX_TYPE))
2978     {
2979       result_type = c_common_type (type1, type2);
2980
2981       /* If -Wsign-compare, warn here if type1 and type2 have
2982          different signedness.  We'll promote the signed to unsigned
2983          and later code won't know it used to be different.
2984          Do this check on the original types, so that explicit casts
2985          will be considered, but default promotions won't.  */
2986       if (warn_sign_compare && !skip_evaluation)
2987         {
2988           int unsigned_op1 = TYPE_UNSIGNED (TREE_TYPE (orig_op1));
2989           int unsigned_op2 = TYPE_UNSIGNED (TREE_TYPE (orig_op2));
2990
2991           if (unsigned_op1 ^ unsigned_op2)
2992             {
2993               /* Do not warn if the result type is signed, since the
2994                  signed type will only be chosen if it can represent
2995                  all the values of the unsigned type.  */
2996               if (!TYPE_UNSIGNED (result_type))
2997                 /* OK */;
2998               /* Do not warn if the signed quantity is an unsuffixed
2999                  integer literal (or some static constant expression
3000                  involving such literals) and it is non-negative.  */
3001               else if ((unsigned_op2 && tree_expr_nonnegative_p (op1))
3002                        || (unsigned_op1 && tree_expr_nonnegative_p (op2)))
3003                 /* OK */;
3004               else
3005                 warning ("signed and unsigned type in conditional expression");
3006             }
3007         }
3008     }
3009   else if (code1 == VOID_TYPE || code2 == VOID_TYPE)
3010     {
3011       if (pedantic && (code1 != VOID_TYPE || code2 != VOID_TYPE))
3012         pedwarn ("ISO C forbids conditional expr with only one void side");
3013       result_type = void_type_node;
3014     }
3015   else if (code1 == POINTER_TYPE && code2 == POINTER_TYPE)
3016     {
3017       if (comp_target_types (type1, type2, 1))
3018         result_type = common_pointer_type (type1, type2);
3019       else if (integer_zerop (op1) && TREE_TYPE (type1) == void_type_node
3020                && TREE_CODE (orig_op1) != NOP_EXPR)
3021         result_type = qualify_type (type2, type1);
3022       else if (integer_zerop (op2) && TREE_TYPE (type2) == void_type_node
3023                && TREE_CODE (orig_op2) != NOP_EXPR)
3024         result_type = qualify_type (type1, type2);
3025       else if (VOID_TYPE_P (TREE_TYPE (type1)))
3026         {
3027           if (pedantic && TREE_CODE (TREE_TYPE (type2)) == FUNCTION_TYPE)
3028             pedwarn ("ISO C forbids conditional expr between "
3029                      "%<void *%> and function pointer");
3030           result_type = build_pointer_type (qualify_type (TREE_TYPE (type1),
3031                                                           TREE_TYPE (type2)));
3032         }
3033       else if (VOID_TYPE_P (TREE_TYPE (type2)))
3034         {
3035           if (pedantic && TREE_CODE (TREE_TYPE (type1)) == FUNCTION_TYPE)
3036             pedwarn ("ISO C forbids conditional expr between "
3037                      "%<void *%> and function pointer");
3038           result_type = build_pointer_type (qualify_type (TREE_TYPE (type2),
3039                                                           TREE_TYPE (type1)));
3040         }
3041       else
3042         {
3043           pedwarn ("pointer type mismatch in conditional expression");
3044           result_type = build_pointer_type (void_type_node);
3045         }
3046     }
3047   else if (code1 == POINTER_TYPE && code2 == INTEGER_TYPE)
3048     {
3049       if (!integer_zerop (op2))
3050         pedwarn ("pointer/integer type mismatch in conditional expression");
3051       else
3052         {
3053           op2 = null_pointer_node;
3054         }
3055       result_type = type1;
3056     }
3057   else if (code2 == POINTER_TYPE && code1 == INTEGER_TYPE)
3058     {
3059       if (!integer_zerop (op1))
3060         pedwarn ("pointer/integer type mismatch in conditional expression");
3061       else
3062         {
3063           op1 = null_pointer_node;
3064         }
3065       result_type = type2;
3066     }
3067
3068   if (!result_type)
3069     {
3070       if (flag_cond_mismatch)
3071         result_type = void_type_node;
3072       else
3073         {
3074           error ("type mismatch in conditional expression");
3075           return error_mark_node;
3076         }
3077     }
3078
3079   /* Merge const and volatile flags of the incoming types.  */
3080   result_type
3081     = build_type_variant (result_type,
3082                           TREE_READONLY (op1) || TREE_READONLY (op2),
3083                           TREE_THIS_VOLATILE (op1) || TREE_THIS_VOLATILE (op2));
3084
3085   if (result_type != TREE_TYPE (op1))
3086     op1 = convert_and_check (result_type, op1);
3087   if (result_type != TREE_TYPE (op2))
3088     op2 = convert_and_check (result_type, op2);
3089
3090   if (TREE_CODE (ifexp) == INTEGER_CST)
3091     return non_lvalue (integer_zerop (ifexp) ? op2 : op1);
3092
3093   return fold (build3 (COND_EXPR, result_type, ifexp, op1, op2));
3094 }
3095 \f
3096 /* Return a compound expression that performs two expressions and
3097    returns the value of the second of them.  */
3098
3099 tree
3100 build_compound_expr (tree expr1, tree expr2)
3101 {
3102   /* Convert arrays and functions to pointers.  */
3103   expr2 = default_function_array_conversion (expr2);
3104
3105   if (!TREE_SIDE_EFFECTS (expr1))
3106     {
3107       /* The left-hand operand of a comma expression is like an expression
3108          statement: with -Wextra or -Wunused, we should warn if it doesn't have
3109          any side-effects, unless it was explicitly cast to (void).  */
3110       if (warn_unused_value
3111            && !(TREE_CODE (expr1) == CONVERT_EXPR
3112                 && VOID_TYPE_P (TREE_TYPE (expr1))))
3113         warning ("left-hand operand of comma expression has no effect");
3114     }
3115
3116   /* With -Wunused, we should also warn if the left-hand operand does have
3117      side-effects, but computes a value which is not used.  For example, in
3118      `foo() + bar(), baz()' the result of the `+' operator is not used,
3119      so we should issue a warning.  */
3120   else if (warn_unused_value)
3121     warn_if_unused_value (expr1, input_location);
3122
3123   return build2 (COMPOUND_EXPR, TREE_TYPE (expr2), expr1, expr2);
3124 }
3125
3126 /* Build an expression representing a cast to type TYPE of expression EXPR.  */
3127
3128 tree
3129 build_c_cast (tree type, tree expr)
3130 {
3131   tree value = expr;
3132
3133   if (type == error_mark_node || expr == error_mark_node)
3134     return error_mark_node;
3135
3136   /* The ObjC front-end uses TYPE_MAIN_VARIANT to tie together types differing
3137      only in <protocol> qualifications.  But when constructing cast expressions,
3138      the protocols do matter and must be kept around.  */
3139   if (objc_is_object_ptr (type) && objc_is_object_ptr (TREE_TYPE (expr)))
3140     return build1 (NOP_EXPR, type, expr);
3141
3142   type = TYPE_MAIN_VARIANT (type);
3143
3144   if (TREE_CODE (type) == ARRAY_TYPE)
3145     {
3146       error ("cast specifies array type");
3147       return error_mark_node;
3148     }
3149
3150   if (TREE_CODE (type) == FUNCTION_TYPE)
3151     {
3152       error ("cast specifies function type");
3153       return error_mark_node;
3154     }
3155
3156   if (type == TYPE_MAIN_VARIANT (TREE_TYPE (value)))
3157     {
3158       if (pedantic)
3159         {
3160           if (TREE_CODE (type) == RECORD_TYPE
3161               || TREE_CODE (type) == UNION_TYPE)
3162             pedwarn ("ISO C forbids casting nonscalar to the same type");
3163         }
3164     }
3165   else if (TREE_CODE (type) == UNION_TYPE)
3166     {
3167       tree field;
3168       value = default_function_array_conversion (value);
3169
3170       for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
3171         if (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (field)),
3172                        TYPE_MAIN_VARIANT (TREE_TYPE (value))))
3173           break;
3174
3175       if (field)
3176         {
3177           tree t;
3178
3179           if (pedantic)
3180             pedwarn ("ISO C forbids casts to union type");
3181           t = digest_init (type,
3182                            build_constructor (type,
3183                                               build_tree_list (field, value)),
3184                            true, 0);
3185           TREE_CONSTANT (t) = TREE_CONSTANT (value);
3186           TREE_INVARIANT (t) = TREE_INVARIANT (value);
3187           return t;
3188         }
3189       error ("cast to union type from type not present in union");
3190       return error_mark_node;
3191     }
3192   else
3193     {
3194       tree otype, ovalue;
3195
3196       /* If casting to void, avoid the error that would come
3197          from default_conversion in the case of a non-lvalue array.  */
3198       if (type == void_type_node)
3199         return build1 (CONVERT_EXPR, type, value);
3200
3201       /* Convert functions and arrays to pointers,
3202          but don't convert any other types.  */
3203       value = default_function_array_conversion (value);
3204       otype = TREE_TYPE (value);
3205
3206       /* Optionally warn about potentially worrisome casts.  */
3207
3208       if (warn_cast_qual
3209           && TREE_CODE (type) == POINTER_TYPE
3210           && TREE_CODE (otype) == POINTER_TYPE)
3211         {
3212           tree in_type = type;
3213           tree in_otype = otype;
3214           int added = 0;
3215           int discarded = 0;
3216
3217           /* Check that the qualifiers on IN_TYPE are a superset of
3218              the qualifiers of IN_OTYPE.  The outermost level of
3219              POINTER_TYPE nodes is uninteresting and we stop as soon
3220              as we hit a non-POINTER_TYPE node on either type.  */
3221           do
3222             {
3223               in_otype = TREE_TYPE (in_otype);
3224               in_type = TREE_TYPE (in_type);
3225
3226               /* GNU C allows cv-qualified function types.  'const'
3227                  means the function is very pure, 'volatile' means it
3228                  can't return.  We need to warn when such qualifiers
3229                  are added, not when they're taken away.  */
3230               if (TREE_CODE (in_otype) == FUNCTION_TYPE
3231                   && TREE_CODE (in_type) == FUNCTION_TYPE)
3232                 added |= (TYPE_QUALS (in_type) & ~TYPE_QUALS (in_otype));
3233               else
3234                 discarded |= (TYPE_QUALS (in_otype) & ~TYPE_QUALS (in_type));
3235             }
3236           while (TREE_CODE (in_type) == POINTER_TYPE
3237                  && TREE_CODE (in_otype) == POINTER_TYPE);
3238
3239           if (added)
3240             warning ("cast adds new qualifiers to function type");
3241
3242           if (discarded)
3243             /* There are qualifiers present in IN_OTYPE that are not
3244                present in IN_TYPE.  */
3245             warning ("cast discards qualifiers from pointer target type");
3246         }
3247
3248       /* Warn about possible alignment problems.  */
3249       if (STRICT_ALIGNMENT && warn_cast_align
3250           && TREE_CODE (type) == POINTER_TYPE
3251           && TREE_CODE (otype) == POINTER_TYPE
3252           && TREE_CODE (TREE_TYPE (otype)) != VOID_TYPE
3253           && TREE_CODE (TREE_TYPE (otype)) != FUNCTION_TYPE
3254           /* Don't warn about opaque types, where the actual alignment
3255              restriction is unknown.  */
3256           && !((TREE_CODE (TREE_TYPE (otype)) == UNION_TYPE
3257                 || TREE_CODE (TREE_TYPE (otype)) == RECORD_TYPE)
3258                && TYPE_MODE (TREE_TYPE (otype)) == VOIDmode)
3259           && TYPE_ALIGN (TREE_TYPE (type)) > TYPE_ALIGN (TREE_TYPE (otype)))
3260         warning ("cast increases required alignment of target type");
3261
3262       if (TREE_CODE (type) == INTEGER_TYPE
3263           && TREE_CODE (otype) == POINTER_TYPE
3264           && TYPE_PRECISION (type) != TYPE_PRECISION (otype)
3265           && !TREE_CONSTANT (value))
3266         warning ("cast from pointer to integer of different size");
3267
3268       if (warn_bad_function_cast
3269           && TREE_CODE (value) == CALL_EXPR
3270           && TREE_CODE (type) != TREE_CODE (otype))
3271         warning ("cast from function call of type %qT to non-matching "
3272                  "type %qT", otype, type);
3273
3274       if (TREE_CODE (type) == POINTER_TYPE
3275           && TREE_CODE (otype) == INTEGER_TYPE
3276           && TYPE_PRECISION (type) != TYPE_PRECISION (otype)
3277           /* Don't warn about converting any constant.  */
3278           && !TREE_CONSTANT (value))
3279         warning ("cast to pointer from integer of different size");
3280
3281       if (TREE_CODE (type) == POINTER_TYPE
3282           && TREE_CODE (otype) == POINTER_TYPE
3283           && TREE_CODE (expr) == ADDR_EXPR
3284           && DECL_P (TREE_OPERAND (expr, 0))
3285           && flag_strict_aliasing && warn_strict_aliasing
3286           && !VOID_TYPE_P (TREE_TYPE (type)))
3287         {
3288           /* Casting the address of a decl to non void pointer. Warn
3289              if the cast breaks type based aliasing.  */
3290           if (!COMPLETE_TYPE_P (TREE_TYPE (type)))
3291             warning ("type-punning to incomplete type might break strict-aliasing rules");
3292           else
3293             {
3294               HOST_WIDE_INT set1 = get_alias_set (TREE_TYPE (TREE_OPERAND (expr, 0)));
3295               HOST_WIDE_INT set2 = get_alias_set (TREE_TYPE (type));
3296
3297               if (!alias_sets_conflict_p (set1, set2))
3298                 warning ("dereferencing type-punned pointer will break strict-aliasing rules");
3299               else if (warn_strict_aliasing > 1
3300                        && !alias_sets_might_conflict_p (set1, set2))
3301                 warning ("dereferencing type-punned pointer might break strict-aliasing rules");
3302             }
3303         }
3304
3305       /* If pedantic, warn for conversions between function and object
3306          pointer types, except for converting a null pointer constant
3307          to function pointer type.  */
3308       if (pedantic
3309           && TREE_CODE (type) == POINTER_TYPE
3310           && TREE_CODE (otype) == POINTER_TYPE
3311           && TREE_CODE (TREE_TYPE (otype)) == FUNCTION_TYPE
3312           && TREE_CODE (TREE_TYPE (type)) != FUNCTION_TYPE)
3313         pedwarn ("ISO C forbids conversion of function pointer to object pointer type");
3314
3315       if (pedantic
3316           && TREE_CODE (type) == POINTER_TYPE
3317           && TREE_CODE (otype) == POINTER_TYPE
3318           && TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE
3319           && TREE_CODE (TREE_TYPE (otype)) != FUNCTION_TYPE
3320           && !(integer_zerop (value) && TREE_TYPE (otype) == void_type_node
3321                && TREE_CODE (expr) != NOP_EXPR))
3322         pedwarn ("ISO C forbids conversion of object pointer to function pointer type");
3323
3324       ovalue = value;
3325       value = convert (type, value);
3326
3327       /* Ignore any integer overflow caused by the cast.  */
3328       if (TREE_CODE (value) == INTEGER_CST)
3329         {
3330           if (EXPR_P (ovalue))
3331             /* If OVALUE had overflow set, then so will VALUE, so it
3332                is safe to overwrite.  */
3333             TREE_OVERFLOW (value) = TREE_OVERFLOW (ovalue);
3334           else
3335             TREE_OVERFLOW (value) = 0;
3336
3337           if (CONSTANT_CLASS_P (ovalue))
3338             /* Similarly, constant_overflow cannot have become
3339                cleared.  */
3340             TREE_CONSTANT_OVERFLOW (value) = TREE_CONSTANT_OVERFLOW (ovalue);
3341         }
3342     }
3343
3344   /* Don't let a cast be an lvalue.  */
3345   if (value == expr)
3346     value = non_lvalue (value);
3347
3348   return value;
3349 }
3350
3351 /* Interpret a cast of expression EXPR to type TYPE.  */
3352 tree
3353 c_cast_expr (struct c_type_name *type_name, tree expr)
3354 {
3355   tree type;
3356   int saved_wsp = warn_strict_prototypes;
3357
3358   /* This avoids warnings about unprototyped casts on
3359      integers.  E.g. "#define SIG_DFL (void(*)())0".  */
3360   if (TREE_CODE (expr) == INTEGER_CST)
3361     warn_strict_prototypes = 0;
3362   type = groktypename (type_name);
3363   warn_strict_prototypes = saved_wsp;
3364
3365   return build_c_cast (type, expr);
3366 }
3367
3368 \f
3369 /* Build an assignment expression of lvalue LHS from value RHS.
3370    MODIFYCODE is the code for a binary operator that we use
3371    to combine the old value of LHS with RHS to get the new value.
3372    Or else MODIFYCODE is NOP_EXPR meaning do a simple assignment.  */
3373
3374 tree
3375 build_modify_expr (tree lhs, enum tree_code modifycode, tree rhs)
3376 {
3377   tree result;
3378   tree newrhs;
3379   tree lhstype = TREE_TYPE (lhs);
3380   tree olhstype = lhstype;
3381
3382   /* Types that aren't fully specified cannot be used in assignments.  */
3383   lhs = require_complete_type (lhs);
3384
3385   /* Avoid duplicate error messages from operands that had errors.  */
3386   if (TREE_CODE (lhs) == ERROR_MARK || TREE_CODE (rhs) == ERROR_MARK)
3387     return error_mark_node;
3388
3389   STRIP_TYPE_NOPS (rhs);
3390
3391   newrhs = rhs;
3392
3393   /* If a binary op has been requested, combine the old LHS value with the RHS
3394      producing the value we should actually store into the LHS.  */
3395
3396   if (modifycode != NOP_EXPR)
3397     {
3398       lhs = stabilize_reference (lhs);
3399       newrhs = build_binary_op (modifycode, lhs, rhs, 1);
3400     }
3401
3402   if (!lvalue_or_else (lhs, lv_assign))
3403     return error_mark_node;
3404
3405   /* Give an error for storing in something that is 'const'.  */
3406
3407   if (TREE_READONLY (lhs) || TYPE_READONLY (lhstype)
3408       || ((TREE_CODE (lhstype) == RECORD_TYPE
3409            || TREE_CODE (lhstype) == UNION_TYPE)
3410           && C_TYPE_FIELDS_READONLY (lhstype)))
3411     readonly_error (lhs, lv_assign);
3412
3413   /* If storing into a structure or union member,
3414      it has probably been given type `int'.
3415      Compute the type that would go with
3416      the actual amount of storage the member occupies.  */
3417
3418   if (TREE_CODE (lhs) == COMPONENT_REF
3419       && (TREE_CODE (lhstype) == INTEGER_TYPE
3420           || TREE_CODE (lhstype) == BOOLEAN_TYPE
3421           || TREE_CODE (lhstype) == REAL_TYPE
3422           || TREE_CODE (lhstype) == ENUMERAL_TYPE))
3423     lhstype = TREE_TYPE (get_unwidened (lhs, 0));
3424
3425   /* If storing in a field that is in actuality a short or narrower than one,
3426      we must store in the field in its actual type.  */
3427
3428   if (lhstype != TREE_TYPE (lhs))
3429     {
3430       lhs = copy_node (lhs);
3431       TREE_TYPE (lhs) = lhstype;
3432     }
3433
3434   /* Convert new value to destination type.  */
3435
3436   newrhs = convert_for_assignment (lhstype, newrhs, ic_assign,
3437                                    NULL_TREE, NULL_TREE, 0);
3438   if (TREE_CODE (newrhs) == ERROR_MARK)
3439     return error_mark_node;
3440
3441   /* Scan operands.  */
3442
3443   result = build2 (MODIFY_EXPR, lhstype, lhs, newrhs);
3444   TREE_SIDE_EFFECTS (result) = 1;
3445
3446   /* If we got the LHS in a different type for storing in,
3447      convert the result back to the nominal type of LHS
3448      so that the value we return always has the same type
3449      as the LHS argument.  */
3450
3451   if (olhstype == TREE_TYPE (result))
3452     return result;
3453   return convert_for_assignment (olhstype, result, ic_assign,
3454                                  NULL_TREE, NULL_TREE, 0);
3455 }
3456 \f
3457 /* Convert value RHS to type TYPE as preparation for an assignment
3458    to an lvalue of type TYPE.
3459    The real work of conversion is done by `convert'.
3460    The purpose of this function is to generate error messages
3461    for assignments that are not allowed in C.
3462    ERRTYPE says whether it is argument passing, assignment,
3463    initialization or return.
3464
3465    FUNCTION is a tree for the function being called.
3466    PARMNUM is the number of the argument, for printing in error messages.  */
3467
3468 static tree
3469 convert_for_assignment (tree type, tree rhs, enum impl_conv errtype,
3470                         tree fundecl, tree function, int parmnum)
3471 {
3472   enum tree_code codel = TREE_CODE (type);
3473   tree rhstype;
3474   enum tree_code coder;
3475   tree rname = NULL_TREE;
3476
3477   if (errtype == ic_argpass || errtype == ic_argpass_nonproto)
3478     {
3479       tree selector;
3480       /* Change pointer to function to the function itself for
3481          diagnostics.  */
3482       if (TREE_CODE (function) == ADDR_EXPR
3483           && TREE_CODE (TREE_OPERAND (function, 0)) == FUNCTION_DECL)
3484         function = TREE_OPERAND (function, 0);
3485
3486       /* Handle an ObjC selector specially for diagnostics.  */
3487       selector = objc_message_selector ();
3488       rname = function;
3489       if (selector && parmnum > 2)
3490         {
3491           rname = selector;
3492           parmnum -= 2;
3493         }
3494     }
3495
3496   /* This macro is used to emit diagnostics to ensure that all format
3497      strings are complete sentences, visible to gettext and checked at
3498      compile time.  */
3499 #define WARN_FOR_ASSIGNMENT(AR, AS, IN, RE)     \
3500   do {                                          \
3501     switch (errtype)                            \
3502       {                                         \
3503       case ic_argpass:                          \
3504         pedwarn (AR, parmnum, rname);           \
3505         break;                                  \
3506       case ic_argpass_nonproto:                 \
3507         warning (AR, parmnum, rname);           \
3508         break;                                  \
3509       case ic_assign:                           \
3510         pedwarn (AS);                           \
3511         break;                                  \
3512       case ic_init:                             \
3513         pedwarn (IN);                           \
3514         break;                                  \
3515       case ic_return:                           \
3516         pedwarn (RE);                           \
3517         break;                                  \
3518       default:                                  \
3519         gcc_unreachable ();                     \
3520       }                                         \
3521   } while (0)
3522
3523   STRIP_TYPE_NOPS (rhs);
3524
3525   if (TREE_CODE (TREE_TYPE (rhs)) == ARRAY_TYPE
3526       || TREE_CODE (TREE_TYPE (rhs)) == FUNCTION_TYPE)
3527     rhs = default_conversion (rhs);
3528   else if (optimize && TREE_CODE (rhs) == VAR_DECL)
3529     rhs = decl_constant_value_for_broken_optimization (rhs);
3530
3531   rhstype = TREE_TYPE (rhs);
3532   coder = TREE_CODE (rhstype);
3533
3534   if (coder == ERROR_MARK)
3535     return error_mark_node;
3536
3537   if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (rhstype))
3538     {
3539       overflow_warning (rhs);
3540       /* Check for Objective-C protocols.  This will automatically
3541          issue a warning if there are protocol violations.  No need to
3542          use the return value.  */
3543       if (c_dialect_objc ())
3544         objc_comptypes (type, rhstype, 0);
3545       return rhs;
3546     }
3547
3548   if (coder == VOID_TYPE)
3549     {
3550       /* Except for passing an argument to an unprototyped function,
3551          this is a constraint violation.  When passing an argument to
3552          an unprototyped function, it is compile-time undefined;
3553          making it a constraint in that case was rejected in
3554          DR#252.  */
3555       error ("void value not ignored as it ought to be");
3556       return error_mark_node;
3557     }
3558   /* A type converts to a reference to it.
3559      This code doesn't fully support references, it's just for the
3560      special case of va_start and va_copy.  */
3561   if (codel == REFERENCE_TYPE
3562       && comptypes (TREE_TYPE (type), TREE_TYPE (rhs)) == 1)
3563     {
3564       if (!lvalue_p (rhs))
3565         {
3566           error ("cannot pass rvalue to reference parameter");
3567           return error_mark_node;
3568         }
3569       if (!c_mark_addressable (rhs))
3570         return error_mark_node;
3571       rhs = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (rhs)), rhs);
3572
3573       /* We already know that these two types are compatible, but they
3574          may not be exactly identical.  In fact, `TREE_TYPE (type)' is
3575          likely to be __builtin_va_list and `TREE_TYPE (rhs)' is
3576          likely to be va_list, a typedef to __builtin_va_list, which
3577          is different enough that it will cause problems later.  */
3578       if (TREE_TYPE (TREE_TYPE (rhs)) != TREE_TYPE (type))
3579         rhs = build1 (NOP_EXPR, build_pointer_type (TREE_TYPE (type)), rhs);
3580
3581       rhs = build1 (NOP_EXPR, type, rhs);
3582       return rhs;
3583     }
3584   /* Some types can interconvert without explicit casts.  */
3585   else if (codel == VECTOR_TYPE && coder == VECTOR_TYPE
3586            && vector_types_convertible_p (type, TREE_TYPE (rhs)))
3587     return convert (type, rhs);
3588   /* Arithmetic types all interconvert, and enum is treated like int.  */
3589   else if ((codel == INTEGER_TYPE || codel == REAL_TYPE
3590             || codel == ENUMERAL_TYPE || codel == COMPLEX_TYPE
3591             || codel == BOOLEAN_TYPE)
3592            && (coder == INTEGER_TYPE || coder == REAL_TYPE
3593                || coder == ENUMERAL_TYPE || coder == COMPLEX_TYPE
3594                || coder == BOOLEAN_TYPE))
3595     return convert_and_check (type, rhs);
3596
3597   /* Conversion to a transparent union from its member types.
3598      This applies only to function arguments.  */
3599   else if (codel == UNION_TYPE && TYPE_TRANSPARENT_UNION (type)
3600            && (errtype == ic_argpass || errtype == ic_argpass_nonproto))
3601     {
3602       tree memb_types;
3603       tree marginal_memb_type = 0;
3604
3605       for (memb_types = TYPE_FIELDS (type); memb_types;
3606            memb_types = TREE_CHAIN (memb_types))
3607         {
3608           tree memb_type = TREE_TYPE (memb_types);
3609
3610           if (comptypes (TYPE_MAIN_VARIANT (memb_type),
3611                          TYPE_MAIN_VARIANT (rhstype)))
3612             break;
3613
3614           if (TREE_CODE (memb_type) != POINTER_TYPE)
3615             continue;
3616
3617           if (coder == POINTER_TYPE)
3618             {
3619               tree ttl = TREE_TYPE (memb_type);
3620               tree ttr = TREE_TYPE (rhstype);
3621
3622               /* Any non-function converts to a [const][volatile] void *
3623                  and vice versa; otherwise, targets must be the same.
3624                  Meanwhile, the lhs target must have all the qualifiers of
3625                  the rhs.  */
3626               if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
3627                   || comp_target_types (memb_type, rhstype, 0))
3628                 {
3629                   /* If this type won't generate any warnings, use it.  */
3630                   if (TYPE_QUALS (ttl) == TYPE_QUALS (ttr)
3631                       || ((TREE_CODE (ttr) == FUNCTION_TYPE
3632                            && TREE_CODE (ttl) == FUNCTION_TYPE)
3633                           ? ((TYPE_QUALS (ttl) | TYPE_QUALS (ttr))
3634                              == TYPE_QUALS (ttr))
3635                           : ((TYPE_QUALS (ttl) | TYPE_QUALS (ttr))
3636                              == TYPE_QUALS (ttl))))
3637                     break;
3638
3639                   /* Keep looking for a better type, but remember this one.  */
3640                   if (!marginal_memb_type)
3641                     marginal_memb_type = memb_type;
3642                 }
3643             }
3644
3645           /* Can convert integer zero to any pointer type.  */
3646           if (integer_zerop (rhs)
3647               || (TREE_CODE (rhs) == NOP_EXPR
3648                   && integer_zerop (TREE_OPERAND (rhs, 0))))
3649             {
3650               rhs = null_pointer_node;
3651               break;
3652             }
3653         }
3654
3655       if (memb_types || marginal_memb_type)
3656         {
3657           if (!memb_types)
3658             {
3659               /* We have only a marginally acceptable member type;
3660                  it needs a warning.  */
3661               tree ttl = TREE_TYPE (marginal_memb_type);
3662               tree ttr = TREE_TYPE (rhstype);
3663
3664               /* Const and volatile mean something different for function
3665                  types, so the usual warnings are not appropriate.  */
3666               if (TREE_CODE (ttr) == FUNCTION_TYPE
3667                   && TREE_CODE (ttl) == FUNCTION_TYPE)
3668                 {
3669                   /* Because const and volatile on functions are
3670                      restrictions that say the function will not do
3671                      certain things, it is okay to use a const or volatile
3672                      function where an ordinary one is wanted, but not
3673                      vice-versa.  */
3674                   if (TYPE_QUALS (ttl) & ~TYPE_QUALS (ttr))
3675                     WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE "
3676                                             "makes qualified function "
3677                                             "pointer from unqualified"),
3678                                          N_("assignment makes qualified "
3679                                             "function pointer from "
3680                                             "unqualified"),
3681                                          N_("initialization makes qualified "
3682                                             "function pointer from "
3683                                             "unqualified"),
3684                                          N_("return makes qualified function "
3685                                             "pointer from unqualified"));
3686                 }
3687               else if (TYPE_QUALS (ttr) & ~TYPE_QUALS (ttl))
3688                 WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE discards "
3689                                         "qualifiers from pointer target type"),
3690                                      N_("assignment discards qualifiers "
3691                                         "from pointer target type"),
3692                                      N_("initialization discards qualifiers "
3693                                         "from pointer target type"),
3694                                      N_("return discards qualifiers from "
3695                                         "pointer target type"));
3696             }
3697
3698           if (pedantic && !DECL_IN_SYSTEM_HEADER (fundecl))
3699             pedwarn ("ISO C prohibits argument conversion to union type");
3700
3701           return build1 (NOP_EXPR, type, rhs);
3702         }
3703     }
3704
3705   /* Conversions among pointers */
3706   else if ((codel == POINTER_TYPE || codel == REFERENCE_TYPE)
3707            && (coder == codel))
3708     {
3709       tree ttl = TREE_TYPE (type);
3710       tree ttr = TREE_TYPE (rhstype);
3711       tree mvl = ttl;
3712       tree mvr = ttr;
3713       bool is_opaque_pointer;
3714       int target_cmp = 0;   /* Cache comp_target_types () result.  */
3715
3716       if (TREE_CODE (mvl) != ARRAY_TYPE)
3717         mvl = TYPE_MAIN_VARIANT (mvl);
3718       if (TREE_CODE (mvr) != ARRAY_TYPE)
3719         mvr = TYPE_MAIN_VARIANT (mvr);
3720       /* Opaque pointers are treated like void pointers.  */
3721       is_opaque_pointer = (targetm.vector_opaque_p (type)
3722                            || targetm.vector_opaque_p (rhstype))
3723         && TREE_CODE (ttl) == VECTOR_TYPE
3724         && TREE_CODE (ttr) == VECTOR_TYPE;
3725
3726       /* Any non-function converts to a [const][volatile] void *
3727          and vice versa; otherwise, targets must be the same.
3728          Meanwhile, the lhs target must have all the qualifiers of the rhs.  */
3729       if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
3730           || (target_cmp = comp_target_types (type, rhstype, 0))
3731           || is_opaque_pointer
3732           || (c_common_unsigned_type (mvl)
3733               == c_common_unsigned_type (mvr)))
3734         {
3735           if (pedantic
3736               && ((VOID_TYPE_P (ttl) && TREE_CODE (ttr) == FUNCTION_TYPE)
3737                   ||
3738                   (VOID_TYPE_P (ttr)
3739                    /* Check TREE_CODE to catch cases like (void *) (char *) 0
3740                       which are not ANSI null ptr constants.  */
3741                    && (!integer_zerop (rhs) || TREE_CODE (rhs) == NOP_EXPR)
3742                    && TREE_CODE (ttl) == FUNCTION_TYPE)))
3743             WARN_FOR_ASSIGNMENT (N_("ISO C forbids passing argument %d of "
3744                                     "%qE between function pointer "
3745                                     "and %<void *%>"),
3746                                  N_("ISO C forbids assignment between "
3747                                     "function pointer and %<void *%>"),
3748                                  N_("ISO C forbids initialization between "
3749                                     "function pointer and %<void *%>"),
3750                                  N_("ISO C forbids return between function "
3751                                     "pointer and %<void *%>"));
3752           /* Const and volatile mean something different for function types,
3753              so the usual warnings are not appropriate.  */
3754           else if (TREE_CODE (ttr) != FUNCTION_TYPE
3755                    && TREE_CODE (ttl) != FUNCTION_TYPE)
3756             {
3757               if (TYPE_QUALS (ttr) & ~TYPE_QUALS (ttl))
3758                 WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE discards "
3759                                         "qualifiers from pointer target type"),
3760                                      N_("assignment discards qualifiers "
3761                                         "from pointer target type"),
3762                                      N_("initialization discards qualifiers "
3763                                         "from pointer target type"),
3764                                      N_("return discards qualifiers from "
3765                                         "pointer target type"));
3766               /* If this is not a case of ignoring a mismatch in signedness,
3767                  no warning.  */
3768               else if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
3769                        || target_cmp)
3770                 ;
3771               /* If there is a mismatch, do warn.  */
3772               else if (warn_pointer_sign)
3773                 WARN_FOR_ASSIGNMENT (N_("pointer targets in passing argument "
3774                                         "%d of %qE differ in signedness"),
3775                                      N_("pointer targets in assignment "
3776                                         "differ in signedness"),
3777                                      N_("pointer targets in initialization "
3778                                         "differ in signedness"),
3779                                      N_("pointer targets in return differ "
3780                                         "in signedness"));
3781             }
3782           else if (TREE_CODE (ttl) == FUNCTION_TYPE
3783                    && TREE_CODE (ttr) == FUNCTION_TYPE)
3784             {
3785               /* Because const and volatile on functions are restrictions
3786                  that say the function will not do certain things,
3787                  it is okay to use a const or volatile function
3788                  where an ordinary one is wanted, but not vice-versa.  */
3789               if (TYPE_QUALS (ttl) & ~TYPE_QUALS (ttr))
3790                 WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE makes "
3791                                         "qualified function pointer "
3792                                         "from unqualified"),
3793                                      N_("assignment makes qualified function "
3794                                         "pointer from unqualified"),
3795                                      N_("initialization makes qualified "
3796                                         "function pointer from unqualified"),
3797                                      N_("return makes qualified function "
3798                                         "pointer from unqualified"));
3799             }
3800         }
3801       else
3802         WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE from "
3803                                 "incompatible pointer type"),
3804                              N_("assignment from incompatible pointer type"),
3805                              N_("initialization from incompatible "
3806                                 "pointer type"),
3807                              N_("return from incompatible pointer type"));
3808       return convert (type, rhs);
3809     }
3810   else if (codel == POINTER_TYPE && coder == ARRAY_TYPE)
3811     {
3812       /* ??? This should not be an error when inlining calls to
3813          unprototyped functions.  */
3814       error ("invalid use of non-lvalue array");
3815       return error_mark_node;
3816     }
3817   else if (codel == POINTER_TYPE && coder == INTEGER_TYPE)
3818     {
3819       /* An explicit constant 0 can convert to a pointer,
3820          or one that results from arithmetic, even including
3821          a cast to integer type.  */
3822       if (!(TREE_CODE (rhs) == INTEGER_CST && integer_zerop (rhs))
3823           &&
3824           !(TREE_CODE (rhs) == NOP_EXPR
3825             && TREE_CODE (TREE_TYPE (rhs)) == INTEGER_TYPE
3826             && TREE_CODE (TREE_OPERAND (rhs, 0)) == INTEGER_CST
3827             && integer_zerop (TREE_OPERAND (rhs, 0))))
3828         WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE makes "
3829                                 "pointer from integer without a cast"),
3830                              N_("assignment makes pointer from integer "
3831                                 "without a cast"),
3832                              N_("initialization makes pointer from "
3833                                 "integer without a cast"),
3834                              N_("return makes pointer from integer "
3835                                 "without a cast"));
3836
3837       return convert (type, rhs);
3838     }
3839   else if (codel == INTEGER_TYPE && coder == POINTER_TYPE)
3840     {
3841       WARN_FOR_ASSIGNMENT (N_("passing argument %d of %qE makes integer "
3842                               "from pointer without a cast"),
3843                            N_("assignment makes integer from pointer "
3844                               "without a cast"),
3845                            N_("initialization makes integer from pointer "
3846                               "without a cast"),
3847                            N_("return makes integer from pointer "
3848                               "without a cast"));
3849       return convert (type, rhs);
3850     }
3851   else if (codel == BOOLEAN_TYPE && coder == POINTER_TYPE)
3852     return convert (type, rhs);
3853
3854   switch (errtype)
3855     {
3856     case ic_argpass:
3857     case ic_argpass_nonproto:
3858       /* ??? This should not be an error when inlining calls to
3859          unprototyped functions.  */
3860       error ("incompatible type for argument %d of %qE", parmnum, rname);
3861       break;
3862     case ic_assign:
3863       error ("incompatible types in assignment");
3864       break;
3865     case ic_init:
3866       error ("incompatible types in initialization");
3867       break;
3868     case ic_return:
3869       error ("incompatible types in return");
3870       break;
3871     default:
3872       gcc_unreachable ();
3873     }
3874
3875   return error_mark_node;
3876 }
3877
3878 /* Convert VALUE for assignment into inlined parameter PARM.  ARGNUM
3879    is used for error and waring reporting and indicates which argument
3880    is being processed.  */
3881
3882 tree
3883 c_convert_parm_for_inlining (tree parm, tree value, tree fn, int argnum)
3884 {
3885   tree ret, type;
3886
3887   /* If FN was prototyped, the value has been converted already
3888      in convert_arguments.  */
3889   if (!value || TYPE_ARG_TYPES (TREE_TYPE (fn)))
3890     return value;
3891
3892   type = TREE_TYPE (parm);
3893   ret = convert_for_assignment (type, value,
3894                                 ic_argpass_nonproto, fn,
3895                                 fn, argnum);
3896   if (targetm.calls.promote_prototypes (TREE_TYPE (fn))
3897       && INTEGRAL_TYPE_P (type)
3898       && (TYPE_PRECISION (type) < TYPE_PRECISION (integer_type_node)))
3899     ret = default_conversion (ret);
3900   return ret;
3901 }
3902 \f
3903 /* If VALUE is a compound expr all of whose expressions are constant, then
3904    return its value.  Otherwise, return error_mark_node.
3905
3906    This is for handling COMPOUND_EXPRs as initializer elements
3907    which is allowed with a warning when -pedantic is specified.  */
3908
3909 static tree
3910 valid_compound_expr_initializer (tree value, tree endtype)
3911 {
3912   if (TREE_CODE (value) == COMPOUND_EXPR)
3913     {
3914       if (valid_compound_expr_initializer (TREE_OPERAND (value, 0), endtype)
3915           == error_mark_node)
3916         return error_mark_node;
3917       return valid_compound_expr_initializer (TREE_OPERAND (value, 1),
3918                                               endtype);
3919     }
3920   else if (!initializer_constant_valid_p (value, endtype))
3921     return error_mark_node;
3922   else
3923     return value;
3924 }
3925 \f
3926 /* Perform appropriate conversions on the initial value of a variable,
3927    store it in the declaration DECL,
3928    and print any error messages that are appropriate.
3929    If the init is invalid, store an ERROR_MARK.  */
3930
3931 void
3932 store_init_value (tree decl, tree init)
3933 {
3934   tree value, type;
3935
3936   /* If variable's type was invalidly declared, just ignore it.  */
3937
3938   type = TREE_TYPE (decl);
3939   if (TREE_CODE (type) == ERROR_MARK)
3940     return;
3941
3942   /* Digest the specified initializer into an expression.  */
3943
3944   value = digest_init (type, init, true, TREE_STATIC (decl));
3945
3946   /* Store the expression if valid; else report error.  */
3947
3948   if (warn_traditional && !in_system_header
3949       && AGGREGATE_TYPE_P (TREE_TYPE (decl)) && !TREE_STATIC (decl))
3950     warning ("traditional C rejects automatic aggregate initialization");
3951
3952   DECL_INITIAL (decl) = value;
3953
3954   /* ANSI wants warnings about out-of-range constant initializers.  */
3955   STRIP_TYPE_NOPS (value);
3956   constant_expression_warning (value);
3957
3958   /* Check if we need to set array size from compound literal size.  */
3959   if (TREE_CODE (type) == ARRAY_TYPE
3960       && TYPE_DOMAIN (type) == 0
3961       && value != error_mark_node)
3962     {
3963       tree inside_init = init;
3964
3965       STRIP_TYPE_NOPS (inside_init);
3966       inside_init = fold (inside_init);
3967
3968       if (TREE_CODE (inside_init) == COMPOUND_LITERAL_EXPR)
3969         {
3970           tree decl = COMPOUND_LITERAL_EXPR_DECL (inside_init);
3971
3972           if (TYPE_DOMAIN (TREE_TYPE (decl)))
3973             {
3974               /* For int foo[] = (int [3]){1}; we need to set array size
3975                  now since later on array initializer will be just the
3976                  brace enclosed list of the compound literal.  */
3977               TYPE_DOMAIN (type) = TYPE_DOMAIN (TREE_TYPE (decl));
3978               layout_type (type);
3979               layout_decl (decl, 0);
3980             }
3981         }
3982     }
3983 }
3984 \f
3985 /* Methods for storing and printing names for error messages.  */
3986
3987 /* Implement a spelling stack that allows components of a name to be pushed
3988    and popped.  Each element on the stack is this structure.  */
3989
3990 struct spelling
3991 {
3992   int kind;
3993   union
3994     {
3995       int i;
3996       const char *s;
3997     } u;
3998 };
3999
4000 #define SPELLING_STRING 1
4001 #define SPELLING_MEMBER 2
4002 #define SPELLING_BOUNDS 3
4003
4004 static struct spelling *spelling;       /* Next stack element (unused).  */
4005 static struct spelling *spelling_base;  /* Spelling stack base.  */
4006 static int spelling_size;               /* Size of the spelling stack.  */
4007
4008 /* Macros to save and restore the spelling stack around push_... functions.
4009    Alternative to SAVE_SPELLING_STACK.  */
4010
4011 #define SPELLING_DEPTH() (spelling - spelling_base)
4012 #define RESTORE_SPELLING_DEPTH(DEPTH) (spelling = spelling_base + (DEPTH))
4013
4014 /* Push an element on the spelling stack with type KIND and assign VALUE
4015    to MEMBER.  */
4016
4017 #define PUSH_SPELLING(KIND, VALUE, MEMBER)                              \
4018 {                                                                       \
4019   int depth = SPELLING_DEPTH ();                                        \
4020                                                                         \
4021   if (depth >= spelling_size)                                           \
4022     {                                                                   \
4023       spelling_size += 10;                                              \
4024       spelling_base = XRESIZEVEC (struct spelling, spelling_base,       \
4025                                   spelling_size);                       \
4026       RESTORE_SPELLING_DEPTH (depth);                                   \
4027     }                                                                   \
4028                                                                         \
4029   spelling->kind = (KIND);                                              \
4030   spelling->MEMBER = (VALUE);                                           \
4031   spelling++;                                                           \
4032 }
4033
4034 /* Push STRING on the stack.  Printed literally.  */
4035
4036 static void
4037 push_string (const char *string)
4038 {
4039   PUSH_SPELLING (SPELLING_STRING, string, u.s);
4040 }
4041
4042 /* Push a member name on the stack.  Printed as '.' STRING.  */
4043
4044 static void
4045 push_member_name (tree decl)
4046 {
4047   const char *const string
4048     = DECL_NAME (decl) ? IDENTIFIER_POINTER (DECL_NAME (decl)) : "<anonymous>";
4049   PUSH_SPELLING (SPELLING_MEMBER, string, u.s);
4050 }
4051
4052 /* Push an array bounds on the stack.  Printed as [BOUNDS].  */
4053
4054 static void
4055 push_array_bounds (int bounds)
4056 {
4057   PUSH_SPELLING (SPELLING_BOUNDS, bounds, u.i);
4058 }
4059
4060 /* Compute the maximum size in bytes of the printed spelling.  */
4061
4062 static int
4063 spelling_length (void)
4064 {
4065   int size = 0;
4066   struct spelling *p;
4067
4068   for (p = spelling_base; p < spelling; p++)
4069     {
4070       if (p->kind == SPELLING_BOUNDS)
4071         size += 25;
4072       else
4073         size += strlen (p->u.s) + 1;
4074     }
4075
4076   return size;
4077 }
4078
4079 /* Print the spelling to BUFFER and return it.  */
4080
4081 static char *
4082 print_spelling (char *buffer)
4083 {
4084   char *d = buffer;
4085   struct spelling *p;
4086
4087   for (p = spelling_base; p < spelling; p++)
4088     if (p->kind == SPELLING_BOUNDS)
4089       {
4090         sprintf (d, "[%d]", p->u.i);
4091         d += strlen (d);
4092       }
4093     else
4094       {
4095         const char *s;
4096         if (p->kind == SPELLING_MEMBER)
4097           *d++ = '.';
4098         for (s = p->u.s; (*d = *s++); d++)
4099           ;
4100       }
4101   *d++ = '\0';
4102   return buffer;
4103 }
4104
4105 /* Issue an error message for a bad initializer component.
4106    MSGID identifies the message.
4107    The component name is taken from the spelling stack.  */
4108
4109 void
4110 error_init (const char *msgid)
4111 {
4112   char *ofwhat;
4113
4114   error ("%s", _(msgid));
4115   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4116   if (*ofwhat)
4117     error ("(near initialization for %qs)", ofwhat);
4118 }
4119
4120 /* Issue a pedantic warning for a bad initializer component.
4121    MSGID identifies the message.
4122    The component name is taken from the spelling stack.  */
4123
4124 void
4125 pedwarn_init (const char *msgid)
4126 {
4127   char *ofwhat;
4128
4129   pedwarn ("%s", _(msgid));
4130   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4131   if (*ofwhat)
4132     pedwarn ("(near initialization for %qs)", ofwhat);
4133 }
4134
4135 /* Issue a warning for a bad initializer component.
4136    MSGID identifies the message.
4137    The component name is taken from the spelling stack.  */
4138
4139 static void
4140 warning_init (const char *msgid)
4141 {
4142   char *ofwhat;
4143
4144   warning ("%s", _(msgid));
4145   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4146   if (*ofwhat)
4147     warning ("(near initialization for %qs)", ofwhat);
4148 }
4149 \f
4150 /* If TYPE is an array type and EXPR is a parenthesized string
4151    constant, warn if pedantic that EXPR is being used to initialize an
4152    object of type TYPE.  */
4153
4154 void
4155 maybe_warn_string_init (tree type, struct c_expr expr)
4156 {
4157   if (pedantic
4158       && TREE_CODE (type) == ARRAY_TYPE
4159       && TREE_CODE (expr.value) == STRING_CST
4160       && expr.original_code != STRING_CST)
4161     pedwarn_init ("array initialized from parenthesized string constant");
4162 }
4163
4164 /* Digest the parser output INIT as an initializer for type TYPE.
4165    Return a C expression of type TYPE to represent the initial value.
4166
4167    If INIT is a string constant, STRICT_STRING is true if it is
4168    unparenthesized or we should not warn here for it being parenthesized.
4169    For other types of INIT, STRICT_STRING is not used.
4170
4171    REQUIRE_CONSTANT requests an error if non-constant initializers or
4172    elements are seen.  */
4173
4174 static tree
4175 digest_init (tree type, tree init, bool strict_string, int require_constant)
4176 {
4177   enum tree_code code = TREE_CODE (type);
4178   tree inside_init = init;
4179
4180   if (type == error_mark_node
4181       || init == error_mark_node
4182       || TREE_TYPE (init) == error_mark_node)
4183     return error_mark_node;
4184
4185   STRIP_TYPE_NOPS (inside_init);
4186
4187   inside_init = fold (inside_init);
4188
4189   /* Initialization of an array of chars from a string constant
4190      optionally enclosed in braces.  */
4191
4192   if (code == ARRAY_TYPE && inside_init
4193       && TREE_CODE (inside_init) == STRING_CST)
4194     {
4195       tree typ1 = TYPE_MAIN_VARIANT (TREE_TYPE (type));
4196       /* Note that an array could be both an array of character type
4197          and an array of wchar_t if wchar_t is signed char or unsigned
4198          char.  */
4199       bool char_array = (typ1 == char_type_node
4200                          || typ1 == signed_char_type_node
4201                          || typ1 == unsigned_char_type_node);
4202       bool wchar_array = !!comptypes (typ1, wchar_type_node);
4203       if (char_array || wchar_array)
4204         {
4205           struct c_expr expr;
4206           bool char_string;
4207           expr.value = inside_init;
4208           expr.original_code = (strict_string ? STRING_CST : ERROR_MARK);
4209           maybe_warn_string_init (type, expr);
4210
4211           char_string
4212             = (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (inside_init)))
4213                == char_type_node);
4214
4215           if (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4216                          TYPE_MAIN_VARIANT (type)))
4217             return inside_init;
4218
4219           if (!wchar_array && !char_string)
4220             {
4221               error_init ("char-array initialized from wide string");
4222               return error_mark_node;
4223             }
4224           if (char_string && !char_array)
4225             {
4226               error_init ("wchar_t-array initialized from non-wide string");
4227               return error_mark_node;
4228             }
4229
4230           TREE_TYPE (inside_init) = type;
4231           if (TYPE_DOMAIN (type) != 0
4232               && TYPE_SIZE (type) != 0
4233               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
4234               /* Subtract 1 (or sizeof (wchar_t))
4235                  because it's ok to ignore the terminating null char
4236                  that is counted in the length of the constant.  */
4237               && 0 > compare_tree_int (TYPE_SIZE_UNIT (type),
4238                                        TREE_STRING_LENGTH (inside_init)
4239                                        - ((TYPE_PRECISION (typ1)
4240                                            != TYPE_PRECISION (char_type_node))
4241                                           ? (TYPE_PRECISION (wchar_type_node)
4242                                              / BITS_PER_UNIT)
4243                                           : 1)))
4244             pedwarn_init ("initializer-string for array of chars is too long");
4245
4246           return inside_init;
4247         }
4248       else if (INTEGRAL_TYPE_P (typ1))
4249         {
4250           error_init ("array of inappropriate type initialized "
4251                       "from string constant");
4252           return error_mark_node;
4253         }
4254     }
4255
4256   /* Build a VECTOR_CST from a *constant* vector constructor.  If the
4257      vector constructor is not constant (e.g. {1,2,3,foo()}) then punt
4258      below and handle as a constructor.  */
4259   if (code == VECTOR_TYPE
4260       && TREE_CODE (TREE_TYPE (inside_init)) == VECTOR_TYPE
4261       && vector_types_convertible_p (TREE_TYPE (inside_init), type)
4262       && TREE_CONSTANT (inside_init))
4263     {
4264       if (TREE_CODE (inside_init) == VECTOR_CST
4265           && comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4266                         TYPE_MAIN_VARIANT (type)))
4267         return inside_init;
4268
4269       if (TREE_CODE (inside_init) == CONSTRUCTOR)
4270         {
4271           tree link;
4272
4273           /* Iterate through elements and check if all constructor
4274              elements are *_CSTs.  */
4275           for (link = CONSTRUCTOR_ELTS (inside_init);
4276                link;
4277                link = TREE_CHAIN (link))
4278             if (! CONSTANT_CLASS_P (TREE_VALUE (link)))
4279               break;
4280
4281           if (link == NULL)
4282             return build_vector (type, CONSTRUCTOR_ELTS (inside_init));
4283         }
4284     }
4285
4286   /* Any type can be initialized
4287      from an expression of the same type, optionally with braces.  */
4288
4289   if (inside_init && TREE_TYPE (inside_init) != 0
4290       && (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4291                      TYPE_MAIN_VARIANT (type))
4292           || (code == ARRAY_TYPE
4293               && comptypes (TREE_TYPE (inside_init), type))
4294           || (code == VECTOR_TYPE
4295               && comptypes (TREE_TYPE (inside_init), type))
4296           || (code == POINTER_TYPE
4297               && TREE_CODE (TREE_TYPE (inside_init)) == ARRAY_TYPE
4298               && comptypes (TREE_TYPE (TREE_TYPE (inside_init)),
4299                             TREE_TYPE (type)))
4300           || (code == POINTER_TYPE
4301               && TREE_CODE (TREE_TYPE (inside_init)) == FUNCTION_TYPE
4302               && comptypes (TREE_TYPE (inside_init),
4303                             TREE_TYPE (type)))))
4304     {
4305       if (code == POINTER_TYPE)
4306         {
4307           inside_init = default_function_array_conversion (inside_init);
4308
4309           if (TREE_CODE (TREE_TYPE (inside_init)) == ARRAY_TYPE)
4310             {
4311               error_init ("invalid use of non-lvalue array");
4312               return error_mark_node;
4313             }
4314          }
4315
4316       if (code == VECTOR_TYPE)
4317         /* Although the types are compatible, we may require a
4318            conversion.  */
4319         inside_init = convert (type, inside_init);
4320
4321       if (require_constant && !flag_isoc99
4322           && TREE_CODE (inside_init) == COMPOUND_LITERAL_EXPR)
4323         {
4324           /* As an extension, allow initializing objects with static storage
4325              duration with compound literals (which are then treated just as
4326              the brace enclosed list they contain).  */
4327           tree decl = COMPOUND_LITERAL_EXPR_DECL (inside_init);
4328           inside_init = DECL_INITIAL (decl);
4329         }
4330
4331       if (code == ARRAY_TYPE && TREE_CODE (inside_init) != STRING_CST
4332           && TREE_CODE (inside_init) != CONSTRUCTOR)
4333         {
4334           error_init ("array initialized from non-constant array expression");
4335           return error_mark_node;
4336         }
4337
4338       if (optimize && TREE_CODE (inside_init) == VAR_DECL)
4339         inside_init = decl_constant_value_for_broken_optimization (inside_init);
4340
4341       /* Compound expressions can only occur here if -pedantic or
4342          -pedantic-errors is specified.  In the later case, we always want
4343          an error.  In the former case, we simply want a warning.  */
4344       if (require_constant && pedantic
4345           && TREE_CODE (inside_init) == COMPOUND_EXPR)
4346         {
4347           inside_init
4348             = valid_compound_expr_initializer (inside_init,
4349                                                TREE_TYPE (inside_init));
4350           if (inside_init == error_mark_node)
4351             error_init ("initializer element is not constant");
4352           else
4353             pedwarn_init ("initializer element is not constant");
4354           if (flag_pedantic_errors)
4355             inside_init = error_mark_node;
4356         }
4357       else if (require_constant
4358                && !initializer_constant_valid_p (inside_init,
4359                                                  TREE_TYPE (inside_init)))
4360         {
4361           error_init ("initializer element is not constant");
4362           inside_init = error_mark_node;
4363         }
4364
4365       return inside_init;
4366     }
4367
4368   /* Handle scalar types, including conversions.  */
4369
4370   if (code == INTEGER_TYPE || code == REAL_TYPE || code == POINTER_TYPE
4371       || code == ENUMERAL_TYPE || code == BOOLEAN_TYPE || code == COMPLEX_TYPE
4372       || code == VECTOR_TYPE)
4373     {
4374       /* Note that convert_for_assignment calls default_conversion
4375          for arrays and functions.  We must not call it in the
4376          case where inside_init is a null pointer constant.  */
4377       inside_init
4378         = convert_for_assignment (type, init, ic_init,
4379                                   NULL_TREE, NULL_TREE, 0);
4380
4381       /* Check to see if we have already given an error message.  */
4382       if (inside_init == error_mark_node)
4383         ;
4384       else if (require_constant && !TREE_CONSTANT (inside_init))
4385         {
4386           error_init ("initializer element is not constant");
4387           inside_init = error_mark_node;
4388         }
4389       else if (require_constant
4390                && !initializer_constant_valid_p (inside_init,
4391                                                  TREE_TYPE (inside_init)))
4392         {
4393           error_init ("initializer element is not computable at load time");
4394           inside_init = error_mark_node;
4395         }
4396
4397       return inside_init;
4398     }
4399
4400   /* Come here only for records and arrays.  */
4401
4402   if (COMPLETE_TYPE_P (type) && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
4403     {
4404       error_init ("variable-sized object may not be initialized");
4405       return error_mark_node;
4406     }
4407
4408   error_init ("invalid initializer");
4409   return error_mark_node;
4410 }
4411 \f
4412 /* Handle initializers that use braces.  */
4413
4414 /* Type of object we are accumulating a constructor for.
4415    This type is always a RECORD_TYPE, UNION_TYPE or ARRAY_TYPE.  */
4416 static tree constructor_type;
4417
4418 /* For a RECORD_TYPE or UNION_TYPE, this is the chain of fields
4419    left to fill.  */
4420 static tree constructor_fields;
4421
4422 /* For an ARRAY_TYPE, this is the specified index
4423    at which to store the next element we get.  */
4424 static tree constructor_index;
4425
4426 /* For an ARRAY_TYPE, this is the maximum index.  */
4427 static tree constructor_max_index;
4428
4429 /* For a RECORD_TYPE, this is the first field not yet written out.  */
4430 static tree constructor_unfilled_fields;
4431
4432 /* For an ARRAY_TYPE, this is the index of the first element
4433    not yet written out.  */
4434 static tree constructor_unfilled_index;
4435
4436 /* In a RECORD_TYPE, the byte index of the next consecutive field.
4437    This is so we can generate gaps between fields, when appropriate.  */
4438 static tree constructor_bit_index;
4439
4440 /* If we are saving up the elements rather than allocating them,
4441    this is the list of elements so far (in reverse order,
4442    most recent first).  */
4443 static tree constructor_elements;
4444
4445 /* 1 if constructor should be incrementally stored into a constructor chain,
4446    0 if all the elements should be kept in AVL tree.  */
4447 static int constructor_incremental;
4448
4449 /* 1 if so far this constructor's elements are all compile-time constants.  */
4450 static int constructor_constant;
4451
4452 /* 1 if so far this constructor's elements are all valid address constants.  */
4453 static int constructor_simple;
4454
4455 /* 1 if this constructor is erroneous so far.  */
4456 static int constructor_erroneous;
4457
4458 /* Structure for managing pending initializer elements, organized as an
4459    AVL tree.  */
4460
4461 struct init_node
4462 {
4463   struct init_node *left, *right;
4464   struct init_node *parent;
4465   int balance;
4466   tree purpose;
4467   tree value;
4468 };
4469
4470 /* Tree of pending elements at this constructor level.
4471    These are elements encountered out of order
4472    which belong at places we haven't reached yet in actually
4473    writing the output.
4474    Will never hold tree nodes across GC runs.  */
4475 static struct init_node *constructor_pending_elts;
4476
4477 /* The SPELLING_DEPTH of this constructor.  */
4478 static int constructor_depth;
4479
4480 /* DECL node for which an initializer is being read.
4481    0 means we are reading a constructor expression
4482    such as (struct foo) {...}.  */
4483 static tree constructor_decl;
4484
4485 /* Nonzero if this is an initializer for a top-level decl.  */
4486 static int constructor_top_level;
4487
4488 /* Nonzero if there were any member designators in this initializer.  */
4489 static int constructor_designated;
4490
4491 /* Nesting depth of designator list.  */
4492 static int designator_depth;
4493
4494 /* Nonzero if there were diagnosed errors in this designator list.  */
4495 static int designator_errorneous;
4496
4497 \f
4498 /* This stack has a level for each implicit or explicit level of
4499    structuring in the initializer, including the outermost one.  It
4500    saves the values of most of the variables above.  */
4501
4502 struct constructor_range_stack;
4503
4504 struct constructor_stack
4505 {
4506   struct constructor_stack *next;
4507   tree type;
4508   tree fields;
4509   tree index;
4510   tree max_index;
4511   tree unfilled_index;
4512   tree unfilled_fields;
4513   tree bit_index;
4514   tree elements;
4515   struct init_node *pending_elts;
4516   int offset;
4517   int depth;
4518   /* If value nonzero, this value should replace the entire
4519      constructor at this level.  */
4520   struct c_expr replacement_value;
4521   struct constructor_range_stack *range_stack;
4522   char constant;
4523   char simple;
4524   char implicit;
4525   char erroneous;
4526   char outer;
4527   char incremental;
4528   char designated;
4529 };
4530
4531 static struct constructor_stack *constructor_stack;
4532
4533 /* This stack represents designators from some range designator up to
4534    the last designator in the list.  */
4535
4536 struct constructor_range_stack
4537 {
4538   struct constructor_range_stack *next, *prev;
4539   struct constructor_stack *stack;
4540   tree range_start;
4541   tree index;
4542   tree range_end;
4543   tree fields;
4544 };
4545
4546 static struct constructor_range_stack *constructor_range_stack;
4547
4548 /* This stack records separate initializers that are nested.
4549    Nested initializers can't happen in ANSI C, but GNU C allows them
4550    in cases like { ... (struct foo) { ... } ... }.  */
4551
4552 struct initializer_stack
4553 {
4554   struct initializer_stack *next;
4555   tree decl;
4556   struct constructor_stack *constructor_stack;
4557   struct constructor_range_stack *constructor_range_stack;
4558   tree elements;
4559   struct spelling *spelling;
4560   struct spelling *spelling_base;
4561   int spelling_size;
4562   char top_level;
4563   char require_constant_value;
4564   char require_constant_elements;
4565 };
4566
4567 static struct initializer_stack *initializer_stack;
4568 \f
4569 /* Prepare to parse and output the initializer for variable DECL.  */
4570
4571 void
4572 start_init (tree decl, tree asmspec_tree ATTRIBUTE_UNUSED, int top_level)
4573 {
4574   const char *locus;
4575   struct initializer_stack *p = xmalloc (sizeof (struct initializer_stack));
4576
4577   p->decl = constructor_decl;
4578   p->require_constant_value = require_constant_value;
4579   p->require_constant_elements = require_constant_elements;
4580   p->constructor_stack = constructor_stack;
4581   p->constructor_range_stack = constructor_range_stack;
4582   p->elements = constructor_elements;
4583   p->spelling = spelling;
4584   p->spelling_base = spelling_base;
4585   p->spelling_size = spelling_size;
4586   p->top_level = constructor_top_level;
4587   p->next = initializer_stack;
4588   initializer_stack = p;
4589
4590   constructor_decl = decl;
4591   constructor_designated = 0;
4592   constructor_top_level = top_level;
4593
4594   if (decl != 0 && decl != error_mark_node)
4595     {
4596       require_constant_value = TREE_STATIC (decl);
4597       require_constant_elements
4598         = ((TREE_STATIC (decl) || (pedantic && !flag_isoc99))
4599            /* For a scalar, you can always use any value to initialize,
4600               even within braces.  */
4601            && (TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE
4602                || TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
4603                || TREE_CODE (TREE_TYPE (decl)) == UNION_TYPE
4604                || TREE_CODE (TREE_TYPE (decl)) == QUAL_UNION_TYPE));
4605       locus = IDENTIFIER_POINTER (DECL_NAME (decl));
4606     }
4607   else
4608     {
4609       require_constant_value = 0;
4610       require_constant_elements = 0;
4611       locus = "(anonymous)";
4612     }
4613
4614   constructor_stack = 0;
4615   constructor_range_stack = 0;
4616
4617   missing_braces_mentioned = 0;
4618
4619   spelling_base = 0;
4620   spelling_size = 0;
4621   RESTORE_SPELLING_DEPTH (0);
4622
4623   if (locus)
4624     push_string (locus);
4625 }
4626
4627 void
4628 finish_init (void)
4629 {
4630   struct initializer_stack *p = initializer_stack;
4631
4632   /* Free the whole constructor stack of this initializer.  */
4633   while (constructor_stack)
4634     {
4635       struct constructor_stack *q = constructor_stack;
4636       constructor_stack = q->next;
4637       free (q);
4638     }
4639
4640   gcc_assert (!constructor_range_stack);
4641
4642   /* Pop back to the data of the outer initializer (if any).  */
4643   free (spelling_base);
4644
4645   constructor_decl = p->decl;
4646   require_constant_value = p->require_constant_value;
4647   require_constant_elements = p->require_constant_elements;
4648   constructor_stack = p->constructor_stack;
4649   constructor_range_stack = p->constructor_range_stack;
4650   constructor_elements = p->elements;
4651   spelling = p->spelling;
4652   spelling_base = p->spelling_base;
4653   spelling_size = p->spelling_size;
4654   constructor_top_level = p->top_level;
4655   initializer_stack = p->next;
4656   free (p);
4657 }
4658 \f
4659 /* Call here when we see the initializer is surrounded by braces.
4660    This is instead of a call to push_init_level;
4661    it is matched by a call to pop_init_level.
4662
4663    TYPE is the type to initialize, for a constructor expression.
4664    For an initializer for a decl, TYPE is zero.  */
4665
4666 void
4667 really_start_incremental_init (tree type)
4668 {
4669   struct constructor_stack *p = XNEW (struct constructor_stack);
4670
4671   if (type == 0)
4672     type = TREE_TYPE (constructor_decl);
4673
4674   if (targetm.vector_opaque_p (type))
4675     error ("opaque vector types cannot be initialized");
4676
4677   p->type = constructor_type;
4678   p->fields = constructor_fields;
4679   p->index = constructor_index;
4680   p->max_index = constructor_max_index;
4681   p->unfilled_index = constructor_unfilled_index;
4682   p->unfilled_fields = constructor_unfilled_fields;
4683   p->bit_index = constructor_bit_index;
4684   p->elements = constructor_elements;
4685   p->constant = constructor_constant;
4686   p->simple = constructor_simple;
4687   p->erroneous = constructor_erroneous;
4688   p->pending_elts = constructor_pending_elts;
4689   p->depth = constructor_depth;
4690   p->replacement_value.value = 0;
4691   p->replacement_value.original_code = ERROR_MARK;
4692   p->implicit = 0;
4693   p->range_stack = 0;
4694   p->outer = 0;
4695   p->incremental = constructor_incremental;
4696   p->designated = constructor_designated;
4697   p->next = 0;
4698   constructor_stack = p;
4699
4700   constructor_constant = 1;
4701   constructor_simple = 1;
4702   constructor_depth = SPELLING_DEPTH ();
4703   constructor_elements = 0;
4704   constructor_pending_elts = 0;
4705   constructor_type = type;
4706   constructor_incremental = 1;
4707   constructor_designated = 0;
4708   designator_depth = 0;
4709   designator_errorneous = 0;
4710
4711   if (TREE_CODE (constructor_type) == RECORD_TYPE
4712       || TREE_CODE (constructor_type) == UNION_TYPE)
4713     {
4714       constructor_fields = TYPE_FIELDS (constructor_type);
4715       /* Skip any nameless bit fields at the beginning.  */
4716       while (constructor_fields != 0 && DECL_C_BIT_FIELD (constructor_fields)
4717              && DECL_NAME (constructor_fields) == 0)
4718         constructor_fields = TREE_CHAIN (constructor_fields);
4719
4720       constructor_unfilled_fields = constructor_fields;
4721       constructor_bit_index = bitsize_zero_node;
4722     }
4723   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
4724     {
4725       if (TYPE_DOMAIN (constructor_type))
4726         {
4727           constructor_max_index
4728             = TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type));
4729
4730           /* Detect non-empty initializations of zero-length arrays.  */
4731           if (constructor_max_index == NULL_TREE
4732               && TYPE_SIZE (constructor_type))
4733             constructor_max_index = build_int_cst (NULL_TREE, -1);
4734
4735           /* constructor_max_index needs to be an INTEGER_CST.  Attempts
4736              to initialize VLAs will cause a proper error; avoid tree
4737              checking errors as well by setting a safe value.  */
4738           if (constructor_max_index
4739               && TREE_CODE (constructor_max_index) != INTEGER_CST)
4740             constructor_max_index = build_int_cst (NULL_TREE, -1);
4741
4742           constructor_index
4743             = convert (bitsizetype,
4744                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
4745         }
4746       else
4747         {
4748           constructor_index = bitsize_zero_node;
4749           constructor_max_index = NULL_TREE;
4750         }
4751
4752       constructor_unfilled_index = constructor_index;
4753     }
4754   else if (TREE_CODE (constructor_type) == VECTOR_TYPE)
4755     {
4756       /* Vectors are like simple fixed-size arrays.  */
4757       constructor_max_index =
4758         build_int_cst (NULL_TREE, TYPE_VECTOR_SUBPARTS (constructor_type) - 1);
4759       constructor_index = convert (bitsizetype, bitsize_zero_node);
4760       constructor_unfilled_index = constructor_index;
4761     }
4762   else
4763     {
4764       /* Handle the case of int x = {5}; */
4765       constructor_fields = constructor_type;
4766       constructor_unfilled_fields = constructor_type;
4767     }
4768 }
4769 \f
4770 /* Push down into a subobject, for initialization.
4771    If this is for an explicit set of braces, IMPLICIT is 0.
4772    If it is because the next element belongs at a lower level,
4773    IMPLICIT is 1 (or 2 if the push is because of designator list).  */
4774
4775 void
4776 push_init_level (int implicit)
4777 {
4778   struct constructor_stack *p;
4779   tree value = NULL_TREE;
4780
4781   /* If we've exhausted any levels that didn't have braces,
4782      pop them now.  */
4783   while (constructor_stack->implicit)
4784     {
4785       if ((TREE_CODE (constructor_type) == RECORD_TYPE
4786            || TREE_CODE (constructor_type) == UNION_TYPE)
4787           && constructor_fields == 0)
4788         process_init_element (pop_init_level (1));
4789       else if (TREE_CODE (constructor_type) == ARRAY_TYPE
4790                && constructor_max_index
4791                && tree_int_cst_lt (constructor_max_index, constructor_index))
4792         process_init_element (pop_init_level (1));
4793       else
4794         break;
4795     }
4796
4797   /* Unless this is an explicit brace, we need to preserve previous
4798      content if any.  */
4799   if (implicit)
4800     {
4801       if ((TREE_CODE (constructor_type) == RECORD_TYPE
4802            || TREE_CODE (constructor_type) == UNION_TYPE)
4803           && constructor_fields)
4804         value = find_init_member (constructor_fields);
4805       else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
4806         value = find_init_member (constructor_index);
4807     }
4808
4809   p = XNEW (struct constructor_stack);
4810   p->type = constructor_type;
4811   p->fields = constructor_fields;
4812   p->index = constructor_index;
4813   p->max_index = constructor_max_index;
4814   p->unfilled_index = constructor_unfilled_index;
4815   p->unfilled_fields = constructor_unfilled_fields;
4816   p->bit_index = constructor_bit_index;
4817   p->elements = constructor_elements;
4818   p->constant = constructor_constant;
4819   p->simple = constructor_simple;
4820   p->erroneous = constructor_erroneous;
4821   p->pending_elts = constructor_pending_elts;
4822   p->depth = constructor_depth;
4823   p->replacement_value.value = 0;
4824   p->replacement_value.original_code = ERROR_MARK;
4825   p->implicit = implicit;
4826   p->outer = 0;
4827   p->incremental = constructor_incremental;
4828   p->designated = constructor_designated;
4829   p->next = constructor_stack;
4830   p->range_stack = 0;
4831   constructor_stack = p;
4832
4833   constructor_constant = 1;
4834   constructor_simple = 1;
4835   constructor_depth = SPELLING_DEPTH ();
4836   constructor_elements = 0;
4837   constructor_incremental = 1;
4838   constructor_designated = 0;
4839   constructor_pending_elts = 0;
4840   if (!implicit)
4841     {
4842       p->range_stack = constructor_range_stack;
4843       constructor_range_stack = 0;
4844       designator_depth = 0;
4845       designator_errorneous = 0;
4846     }
4847
4848   /* Don't die if an entire brace-pair level is superfluous
4849      in the containing level.  */
4850   if (constructor_type == 0)
4851     ;
4852   else if (TREE_CODE (constructor_type) == RECORD_TYPE
4853            || TREE_CODE (constructor_type) == UNION_TYPE)
4854     {
4855       /* Don't die if there are extra init elts at the end.  */
4856       if (constructor_fields == 0)
4857         constructor_type = 0;
4858       else
4859         {
4860           constructor_type = TREE_TYPE (constructor_fields);
4861           push_member_name (constructor_fields);
4862           constructor_depth++;
4863         }
4864     }
4865   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
4866     {
4867       constructor_type = TREE_TYPE (constructor_type);
4868       push_array_bounds (tree_low_cst (constructor_index, 0));
4869       constructor_depth++;
4870     }
4871
4872   if (constructor_type == 0)
4873     {
4874       error_init ("extra brace group at end of initializer");
4875       constructor_fields = 0;
4876       constructor_unfilled_fields = 0;
4877       return;
4878     }
4879
4880   if (value && TREE_CODE (value) == CONSTRUCTOR)
4881     {
4882       constructor_constant = TREE_CONSTANT (value);
4883       constructor_simple = TREE_STATIC (value);
4884       constructor_elements = CONSTRUCTOR_ELTS (value);
4885       if (constructor_elements
4886           && (TREE_CODE (constructor_type) == RECORD_TYPE
4887               || TREE_CODE (constructor_type) == ARRAY_TYPE))
4888         set_nonincremental_init ();
4889     }
4890
4891   if (implicit == 1 && warn_missing_braces && !missing_braces_mentioned)
4892     {
4893       missing_braces_mentioned = 1;
4894       warning_init ("missing braces around initializer");
4895     }
4896
4897   if (TREE_CODE (constructor_type) == RECORD_TYPE
4898            || TREE_CODE (constructor_type) == UNION_TYPE)
4899     {
4900       constructor_fields = TYPE_FIELDS (constructor_type);
4901       /* Skip any nameless bit fields at the beginning.  */
4902       while (constructor_fields != 0 && DECL_C_BIT_FIELD (constructor_fields)
4903              && DECL_NAME (constructor_fields) == 0)
4904         constructor_fields = TREE_CHAIN (constructor_fields);
4905
4906       constructor_unfilled_fields = constructor_fields;
4907       constructor_bit_index = bitsize_zero_node;
4908     }
4909   else if (TREE_CODE (constructor_type) == VECTOR_TYPE)
4910     {
4911       /* Vectors are like simple fixed-size arrays.  */
4912       constructor_max_index =
4913         build_int_cst (NULL_TREE, TYPE_VECTOR_SUBPARTS (constructor_type) - 1);
4914       constructor_index = convert (bitsizetype, integer_zero_node);
4915       constructor_unfilled_index = constructor_index;
4916     }
4917   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
4918     {
4919       if (TYPE_DOMAIN (constructor_type))
4920         {
4921           constructor_max_index
4922             = TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type));
4923
4924           /* Detect non-empty initializations of zero-length arrays.  */
4925           if (constructor_max_index == NULL_TREE
4926               && TYPE_SIZE (constructor_type))
4927             constructor_max_index = build_int_cst (NULL_TREE, -1);
4928
4929           /* constructor_max_index needs to be an INTEGER_CST.  Attempts
4930              to initialize VLAs will cause a proper error; avoid tree
4931              checking errors as well by setting a safe value.  */
4932           if (constructor_max_index
4933               && TREE_CODE (constructor_max_index) != INTEGER_CST)
4934             constructor_max_index = build_int_cst (NULL_TREE, -1);
4935
4936           constructor_index
4937             = convert (bitsizetype,
4938                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
4939         }
4940       else
4941         constructor_index = bitsize_zero_node;
4942
4943       constructor_unfilled_index = constructor_index;
4944       if (value && TREE_CODE (value) == STRING_CST)
4945         {
4946           /* We need to split the char/wchar array into individual
4947              characters, so that we don't have to special case it
4948              everywhere.  */
4949           set_nonincremental_init_from_string (value);
4950         }
4951     }
4952   else
4953     {
4954       if (constructor_type != error_mark_node)
4955         warning_init ("braces around scalar initializer");
4956       constructor_fields = constructor_type;
4957       constructor_unfilled_fields = constructor_type;
4958     }
4959 }
4960
4961 /* At the end of an implicit or explicit brace level,
4962    finish up that level of constructor.  If a single expression
4963    with redundant braces initialized that level, return the
4964    c_expr structure for that expression.  Otherwise, the original_code
4965    element is set to ERROR_MARK.
4966    If we were outputting the elements as they are read, return 0 as the value
4967    from inner levels (process_init_element ignores that),
4968    but return error_mark_node as the value from the outermost level
4969    (that's what we want to put in DECL_INITIAL).
4970    Otherwise, return a CONSTRUCTOR expression as the value.  */
4971
4972 struct c_expr
4973 pop_init_level (int implicit)
4974 {
4975   struct constructor_stack *p;
4976   struct c_expr ret;
4977   ret.value = 0;
4978   ret.original_code = ERROR_MARK;
4979
4980   if (implicit == 0)
4981     {
4982       /* When we come to an explicit close brace,
4983          pop any inner levels that didn't have explicit braces.  */
4984       while (constructor_stack->implicit)
4985         process_init_element (pop_init_level (1));
4986
4987       gcc_assert (!constructor_range_stack);
4988     }
4989
4990   /* Now output all pending elements.  */
4991   constructor_incremental = 1;
4992   output_pending_init_elements (1);
4993
4994   p = constructor_stack;
4995
4996   /* Error for initializing a flexible array member, or a zero-length
4997      array member in an inappropriate context.  */
4998   if (constructor_type && constructor_fields
4999       && TREE_CODE (constructor_type) == ARRAY_TYPE
5000       && TYPE_DOMAIN (constructor_type)
5001       && !TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type)))
5002     {
5003       /* Silently discard empty initializations.  The parser will
5004          already have pedwarned for empty brackets.  */
5005       if (integer_zerop (constructor_unfilled_index))
5006         constructor_type = NULL_TREE;
5007       else
5008         {
5009           gcc_assert (!TYPE_SIZE (constructor_type));
5010
5011           if (constructor_depth > 2)
5012             error_init ("initialization of flexible array member in a nested context");
5013           else if (pedantic)
5014             pedwarn_init ("initialization of a flexible array member");
5015
5016           /* We have already issued an error message for the existence
5017              of a flexible array member not at the end of the structure.
5018              Discard the initializer so that we do not abort later.  */
5019           if (TREE_CHAIN (constructor_fields) != NULL_TREE)
5020             constructor_type = NULL_TREE;
5021         }
5022     }
5023
5024   /* Warn when some struct elements are implicitly initialized to zero.  */
5025   if (warn_missing_field_initializers
5026       && constructor_type
5027       && TREE_CODE (constructor_type) == RECORD_TYPE
5028       && constructor_unfilled_fields)
5029     {
5030         /* Do not warn for flexible array members or zero-length arrays.  */
5031         while (constructor_unfilled_fields
5032                && (!DECL_SIZE (constructor_unfilled_fields)
5033                    || integer_zerop (DECL_SIZE (constructor_unfilled_fields))))
5034           constructor_unfilled_fields = TREE_CHAIN (constructor_unfilled_fields);
5035
5036         /* Do not warn if this level of the initializer uses member
5037            designators; it is likely to be deliberate.  */
5038         if (constructor_unfilled_fields && !constructor_designated)
5039           {
5040             push_member_name (constructor_unfilled_fields);
5041             warning_init ("missing initializer");
5042             RESTORE_SPELLING_DEPTH (constructor_depth);
5043           }
5044     }
5045
5046   /* Pad out the end of the structure.  */
5047   if (p->replacement_value.value)
5048     /* If this closes a superfluous brace pair,
5049        just pass out the element between them.  */
5050     ret = p->replacement_value;
5051   else if (constructor_type == 0)
5052     ;
5053   else if (TREE_CODE (constructor_type) != RECORD_TYPE
5054            && TREE_CODE (constructor_type) != UNION_TYPE
5055            && TREE_CODE (constructor_type) != ARRAY_TYPE
5056            && TREE_CODE (constructor_type) != VECTOR_TYPE)
5057     {
5058       /* A nonincremental scalar initializer--just return
5059          the element, after verifying there is just one.  */
5060       if (constructor_elements == 0)
5061         {
5062           if (!constructor_erroneous)
5063             error_init ("empty scalar initializer");
5064           ret.value = error_mark_node;
5065         }
5066       else if (TREE_CHAIN (constructor_elements) != 0)
5067         {
5068           error_init ("extra elements in scalar initializer");
5069           ret.value = TREE_VALUE (constructor_elements);
5070         }
5071       else
5072         ret.value = TREE_VALUE (constructor_elements);
5073     }
5074   else
5075     {
5076       if (constructor_erroneous)
5077         ret.value = error_mark_node;
5078       else
5079         {
5080           ret.value = build_constructor (constructor_type,
5081                                          nreverse (constructor_elements));
5082           if (constructor_constant)
5083             TREE_CONSTANT (ret.value) = TREE_INVARIANT (ret.value) = 1;
5084           if (constructor_constant && constructor_simple)
5085             TREE_STATIC (ret.value) = 1;
5086         }
5087     }
5088
5089   constructor_type = p->type;
5090   constructor_fields = p->fields;
5091   constructor_index = p->index;
5092   constructor_max_index = p->max_index;
5093   constructor_unfilled_index = p->unfilled_index;
5094   constructor_unfilled_fields = p->unfilled_fields;
5095   constructor_bit_index = p->bit_index;
5096   constructor_elements = p->elements;
5097   constructor_constant = p->constant;
5098   constructor_simple = p->simple;
5099   constructor_erroneous = p->erroneous;
5100   constructor_incremental = p->incremental;
5101   constructor_designated = p->designated;
5102   constructor_pending_elts = p->pending_elts;
5103   constructor_depth = p->depth;
5104   if (!p->implicit)
5105     constructor_range_stack = p->range_stack;
5106   RESTORE_SPELLING_DEPTH (constructor_depth);
5107
5108   constructor_stack = p->next;
5109   free (p);
5110
5111   if (ret.value == 0)
5112     {
5113       if (constructor_stack == 0)
5114         {
5115           ret.value = error_mark_node;
5116           return ret;
5117         }
5118       return ret;
5119     }
5120   return ret;
5121 }
5122
5123 /* Common handling for both array range and field name designators.
5124    ARRAY argument is nonzero for array ranges.  Returns zero for success.  */
5125
5126 static int
5127 set_designator (int array)
5128 {
5129   tree subtype;
5130   enum tree_code subcode;
5131
5132   /* Don't die if an entire brace-pair level is superfluous
5133      in the containing level.  */
5134   if (constructor_type == 0)
5135     return 1;
5136
5137   /* If there were errors in this designator list already, bail out
5138      silently.  */
5139   if (designator_errorneous)
5140     return 1;
5141
5142   if (!designator_depth)
5143     {
5144       gcc_assert (!constructor_range_stack);
5145
5146       /* Designator list starts at the level of closest explicit
5147          braces.  */
5148       while (constructor_stack->implicit)
5149         process_init_element (pop_init_level (1));
5150       constructor_designated = 1;
5151       return 0;
5152     }
5153
5154   switch (TREE_CODE (constructor_type))
5155     {
5156     case  RECORD_TYPE:
5157     case  UNION_TYPE:
5158       subtype = TREE_TYPE (constructor_fields);
5159       if (subtype != error_mark_node)
5160         subtype = TYPE_MAIN_VARIANT (subtype);
5161       break;
5162     case ARRAY_TYPE:
5163       subtype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
5164       break;
5165     default:
5166       gcc_unreachable ();
5167     }
5168
5169   subcode = TREE_CODE (subtype);
5170   if (array && subcode != ARRAY_TYPE)
5171     {
5172       error_init ("array index in non-array initializer");
5173       return 1;
5174     }
5175   else if (!array && subcode != RECORD_TYPE && subcode != UNION_TYPE)
5176     {
5177       error_init ("field name not in record or union initializer");
5178       return 1;
5179     }
5180
5181   constructor_designated = 1;
5182   push_init_level (2);
5183   return 0;
5184 }
5185
5186 /* If there are range designators in designator list, push a new designator
5187    to constructor_range_stack.  RANGE_END is end of such stack range or
5188    NULL_TREE if there is no range designator at this level.  */
5189
5190 static void
5191 push_range_stack (tree range_end)
5192 {
5193   struct constructor_range_stack *p;
5194
5195   p = GGC_NEW (struct constructor_range_stack);
5196   p->prev = constructor_range_stack;
5197   p->next = 0;
5198   p->fields = constructor_fields;
5199   p->range_start = constructor_index;
5200   p->index = constructor_index;
5201   p->stack = constructor_stack;
5202   p->range_end = range_end;
5203   if (constructor_range_stack)
5204     constructor_range_stack->next = p;
5205   constructor_range_stack = p;
5206 }
5207
5208 /* Within an array initializer, specify the next index to be initialized.
5209    FIRST is that index.  If LAST is nonzero, then initialize a range
5210    of indices, running from FIRST through LAST.  */
5211
5212 void
5213 set_init_index (tree first, tree last)
5214 {
5215   if (set_designator (1))
5216     return;
5217
5218   designator_errorneous = 1;
5219
5220   if (!INTEGRAL_TYPE_P (TREE_TYPE (first))
5221       || (last && !INTEGRAL_TYPE_P (TREE_TYPE (last))))
5222     {
5223       error_init ("array index in initializer not of integer type");
5224       return;
5225     }
5226
5227   if (TREE_CODE (first) != INTEGER_CST)
5228     error_init ("nonconstant array index in initializer");
5229   else if (last != 0 && TREE_CODE (last) != INTEGER_CST)
5230     error_init ("nonconstant array index in initializer");
5231   else if (TREE_CODE (constructor_type) != ARRAY_TYPE)
5232     error_init ("array index in non-array initializer");
5233   else if (tree_int_cst_sgn (first) == -1)
5234     error_init ("array index in initializer exceeds array bounds");
5235   else if (constructor_max_index
5236            && tree_int_cst_lt (constructor_max_index, first))
5237     error_init ("array index in initializer exceeds array bounds");
5238   else
5239     {
5240       constructor_index = convert (bitsizetype, first);
5241
5242       if (last)
5243         {
5244           if (tree_int_cst_equal (first, last))
5245             last = 0;
5246           else if (tree_int_cst_lt (last, first))
5247             {
5248               error_init ("empty index range in initializer");
5249               last = 0;
5250             }
5251           else
5252             {
5253               last = convert (bitsizetype, last);
5254               if (constructor_max_index != 0
5255                   && tree_int_cst_lt (constructor_max_index, last))
5256                 {
5257                   error_init ("array index range in initializer exceeds array bounds");
5258                   last = 0;
5259                 }
5260             }
5261         }
5262
5263       designator_depth++;
5264       designator_errorneous = 0;
5265       if (constructor_range_stack || last)
5266         push_range_stack (last);
5267     }
5268 }
5269
5270 /* Within a struct initializer, specify the next field to be initialized.  */
5271
5272 void
5273 set_init_label (tree fieldname)
5274 {
5275   tree tail;
5276
5277   if (set_designator (0))
5278     return;
5279
5280   designator_errorneous = 1;
5281
5282   if (TREE_CODE (constructor_type) != RECORD_TYPE
5283       && TREE_CODE (constructor_type) != UNION_TYPE)
5284     {
5285       error_init ("field name not in record or union initializer");
5286       return;
5287     }
5288
5289   for (tail = TYPE_FIELDS (constructor_type); tail;
5290        tail = TREE_CHAIN (tail))
5291     {
5292       if (DECL_NAME (tail) == fieldname)
5293         break;
5294     }
5295
5296   if (tail == 0)
5297     error ("unknown field %qE specified in initializer", fieldname);
5298   else
5299     {
5300       constructor_fields = tail;
5301       designator_depth++;
5302       designator_errorneous = 0;
5303       if (constructor_range_stack)
5304         push_range_stack (NULL_TREE);
5305     }
5306 }
5307 \f
5308 /* Add a new initializer to the tree of pending initializers.  PURPOSE
5309    identifies the initializer, either array index or field in a structure.
5310    VALUE is the value of that index or field.  */
5311
5312 static void
5313 add_pending_init (tree purpose, tree value)
5314 {
5315   struct init_node *p, **q, *r;
5316
5317   q = &constructor_pending_elts;
5318   p = 0;
5319
5320   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5321     {
5322       while (*q != 0)
5323         {
5324           p = *q;
5325           if (tree_int_cst_lt (purpose, p->purpose))
5326             q = &p->left;
5327           else if (tree_int_cst_lt (p->purpose, purpose))
5328             q = &p->right;
5329           else
5330             {
5331               if (TREE_SIDE_EFFECTS (p->value))
5332                 warning_init ("initialized field with side-effects overwritten");
5333               p->value = value;
5334               return;
5335             }
5336         }
5337     }
5338   else
5339     {
5340       tree bitpos;
5341
5342       bitpos = bit_position (purpose);
5343       while (*q != NULL)
5344         {
5345           p = *q;
5346           if (tree_int_cst_lt (bitpos, bit_position (p->purpose)))
5347             q = &p->left;
5348           else if (p->purpose != purpose)
5349             q = &p->right;
5350           else
5351             {
5352               if (TREE_SIDE_EFFECTS (p->value))
5353                 warning_init ("initialized field with side-effects overwritten");
5354               p->value = value;
5355               return;
5356             }
5357         }
5358     }
5359
5360   r = GGC_NEW (struct init_node);
5361   r->purpose = purpose;
5362   r->value = value;
5363
5364   *q = r;
5365   r->parent = p;
5366   r->left = 0;
5367   r->right = 0;
5368   r->balance = 0;
5369
5370   while (p)
5371     {
5372       struct init_node *s;
5373
5374       if (r == p->left)
5375         {
5376           if (p->balance == 0)
5377             p->balance = -1;
5378           else if (p->balance < 0)
5379             {
5380               if (r->balance < 0)
5381                 {
5382                   /* L rotation.  */
5383                   p->left = r->right;
5384                   if (p->left)
5385                     p->left->parent = p;
5386                   r->right = p;
5387
5388                   p->balance = 0;
5389                   r->balance = 0;
5390
5391                   s = p->parent;
5392                   p->parent = r;
5393                   r->parent = s;
5394                   if (s)
5395                     {
5396                       if (s->left == p)
5397                         s->left = r;
5398                       else
5399                         s->right = r;
5400                     }
5401                   else
5402                     constructor_pending_elts = r;
5403                 }
5404               else
5405                 {
5406                   /* LR rotation.  */
5407                   struct init_node *t = r->right;
5408
5409                   r->right = t->left;
5410                   if (r->right)
5411                     r->right->parent = r;
5412                   t->left = r;
5413
5414                   p->left = t->right;
5415                   if (p->left)
5416                     p->left->parent = p;
5417                   t->right = p;
5418
5419                   p->balance = t->balance < 0;
5420                   r->balance = -(t->balance > 0);
5421                   t->balance = 0;
5422
5423                   s = p->parent;
5424                   p->parent = t;
5425                   r->parent = t;
5426                   t->parent = s;
5427                   if (s)
5428                     {
5429                       if (s->left == p)
5430                         s->left = t;
5431                       else
5432                         s->right = t;
5433                     }
5434                   else
5435                     constructor_pending_elts = t;
5436                 }
5437               break;
5438             }
5439           else
5440             {
5441               /* p->balance == +1; growth of left side balances the node.  */
5442               p->balance = 0;
5443               break;
5444             }
5445         }
5446       else /* r == p->right */
5447         {
5448           if (p->balance == 0)
5449             /* Growth propagation from right side.  */
5450             p->balance++;
5451           else if (p->balance > 0)
5452             {
5453               if (r->balance > 0)
5454                 {
5455                   /* R rotation.  */
5456                   p->right = r->left;
5457                   if (p->right)
5458                     p->right->parent = p;
5459                   r->left = p;
5460
5461                   p->balance = 0;
5462                   r->balance = 0;
5463
5464                   s = p->parent;
5465                   p->parent = r;
5466                   r->parent = s;
5467                   if (s)
5468                     {
5469                       if (s->left == p)
5470                         s->left = r;
5471                       else
5472                         s->right = r;
5473                     }
5474                   else
5475                     constructor_pending_elts = r;
5476                 }
5477               else /* r->balance == -1 */
5478                 {
5479                   /* RL rotation */
5480                   struct init_node *t = r->left;
5481
5482                   r->left = t->right;
5483                   if (r->left)
5484                     r->left->parent = r;
5485                   t->right = r;
5486
5487                   p->right = t->left;
5488                   if (p->right)
5489                     p->right->parent = p;
5490                   t->left = p;
5491
5492                   r->balance = (t->balance < 0);
5493                   p->balance = -(t->balance > 0);
5494                   t->balance = 0;
5495
5496                   s = p->parent;
5497                   p->parent = t;
5498                   r->parent = t;
5499                   t->parent = s;
5500                   if (s)
5501                     {
5502                       if (s->left == p)
5503                         s->left = t;
5504                       else
5505                         s->right = t;
5506                     }
5507                   else
5508                     constructor_pending_elts = t;
5509                 }
5510               break;
5511             }
5512           else
5513             {
5514               /* p->balance == -1; growth of right side balances the node.  */
5515               p->balance = 0;
5516               break;
5517             }
5518         }
5519
5520       r = p;
5521       p = p->parent;
5522     }
5523 }
5524
5525 /* Build AVL tree from a sorted chain.  */
5526
5527 static void
5528 set_nonincremental_init (void)
5529 {
5530   tree chain;
5531
5532   if (TREE_CODE (constructor_type) != RECORD_TYPE
5533       && TREE_CODE (constructor_type) != ARRAY_TYPE)
5534     return;
5535
5536   for (chain = constructor_elements; chain; chain = TREE_CHAIN (chain))
5537     add_pending_init (TREE_PURPOSE (chain), TREE_VALUE (chain));
5538   constructor_elements = 0;
5539   if (TREE_CODE (constructor_type) == RECORD_TYPE)
5540     {
5541       constructor_unfilled_fields = TYPE_FIELDS (constructor_type);
5542       /* Skip any nameless bit fields at the beginning.  */
5543       while (constructor_unfilled_fields != 0
5544              && DECL_C_BIT_FIELD (constructor_unfilled_fields)
5545              && DECL_NAME (constructor_unfilled_fields) == 0)
5546         constructor_unfilled_fields = TREE_CHAIN (constructor_unfilled_fields);
5547
5548     }
5549   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5550     {
5551       if (TYPE_DOMAIN (constructor_type))
5552         constructor_unfilled_index
5553             = convert (bitsizetype,
5554                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
5555       else
5556         constructor_unfilled_index = bitsize_zero_node;
5557     }
5558   constructor_incremental = 0;
5559 }
5560
5561 /* Build AVL tree from a string constant.  */
5562
5563 static void
5564 set_nonincremental_init_from_string (tree str)
5565 {
5566   tree value, purpose, type;
5567   HOST_WIDE_INT val[2];
5568   const char *p, *end;
5569   int byte, wchar_bytes, charwidth, bitpos;
5570
5571   gcc_assert (TREE_CODE (constructor_type) == ARRAY_TYPE);
5572
5573   if (TYPE_PRECISION (TREE_TYPE (TREE_TYPE (str)))
5574       == TYPE_PRECISION (char_type_node))
5575     wchar_bytes = 1;
5576   else
5577     {
5578       gcc_assert (TYPE_PRECISION (TREE_TYPE (TREE_TYPE (str)))
5579                   == TYPE_PRECISION (wchar_type_node));
5580       wchar_bytes = TYPE_PRECISION (wchar_type_node) / BITS_PER_UNIT;
5581     }
5582   charwidth = TYPE_PRECISION (char_type_node);
5583   type = TREE_TYPE (constructor_type);
5584   p = TREE_STRING_POINTER (str);
5585   end = p + TREE_STRING_LENGTH (str);
5586
5587   for (purpose = bitsize_zero_node;
5588        p < end && !tree_int_cst_lt (constructor_max_index, purpose);
5589        purpose = size_binop (PLUS_EXPR, purpose, bitsize_one_node))
5590     {
5591       if (wchar_bytes == 1)
5592         {
5593           val[1] = (unsigned char) *p++;
5594           val[0] = 0;
5595         }
5596       else
5597         {
5598           val[0] = 0;
5599           val[1] = 0;
5600           for (byte = 0; byte < wchar_bytes; byte++)
5601             {
5602               if (BYTES_BIG_ENDIAN)
5603                 bitpos = (wchar_bytes - byte - 1) * charwidth;
5604               else
5605                 bitpos = byte * charwidth;
5606               val[bitpos < HOST_BITS_PER_WIDE_INT]
5607                 |= ((unsigned HOST_WIDE_INT) ((unsigned char) *p++))
5608                    << (bitpos % HOST_BITS_PER_WIDE_INT);
5609             }
5610         }
5611
5612       if (!TYPE_UNSIGNED (type))
5613         {
5614           bitpos = ((wchar_bytes - 1) * charwidth) + HOST_BITS_PER_CHAR;
5615           if (bitpos < HOST_BITS_PER_WIDE_INT)
5616             {
5617               if (val[1] & (((HOST_WIDE_INT) 1) << (bitpos - 1)))
5618                 {
5619                   val[1] |= ((HOST_WIDE_INT) -1) << bitpos;
5620                   val[0] = -1;
5621                 }
5622             }
5623           else if (bitpos == HOST_BITS_PER_WIDE_INT)
5624             {
5625               if (val[1] < 0)
5626                 val[0] = -1;
5627             }
5628           else if (val[0] & (((HOST_WIDE_INT) 1)
5629                              << (bitpos - 1 - HOST_BITS_PER_WIDE_INT)))
5630             val[0] |= ((HOST_WIDE_INT) -1)
5631                       << (bitpos - HOST_BITS_PER_WIDE_INT);
5632         }
5633
5634       value = build_int_cst_wide (type, val[1], val[0]);
5635       add_pending_init (purpose, value);
5636     }
5637
5638   constructor_incremental = 0;
5639 }
5640
5641 /* Return value of FIELD in pending initializer or zero if the field was
5642    not initialized yet.  */
5643
5644 static tree
5645 find_init_member (tree field)
5646 {
5647   struct init_node *p;
5648
5649   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5650     {
5651       if (constructor_incremental
5652           && tree_int_cst_lt (field, constructor_unfilled_index))
5653         set_nonincremental_init ();
5654
5655       p = constructor_pending_elts;
5656       while (p)
5657         {
5658           if (tree_int_cst_lt (field, p->purpose))
5659             p = p->left;
5660           else if (tree_int_cst_lt (p->purpose, field))
5661             p = p->right;
5662           else
5663             return p->value;
5664         }
5665     }
5666   else if (TREE_CODE (constructor_type) == RECORD_TYPE)
5667     {
5668       tree bitpos = bit_position (field);
5669
5670       if (constructor_incremental
5671           && (!constructor_unfilled_fields
5672               || tree_int_cst_lt (bitpos,
5673                                   bit_position (constructor_unfilled_fields))))
5674         set_nonincremental_init ();
5675
5676       p = constructor_pending_elts;
5677       while (p)
5678         {
5679           if (field == p->purpose)
5680             return p->value;
5681           else if (tree_int_cst_lt (bitpos, bit_position (p->purpose)))
5682             p = p->left;
5683           else
5684             p = p->right;
5685         }
5686     }
5687   else if (TREE_CODE (constructor_type) == UNION_TYPE)
5688     {
5689       if (constructor_elements
5690           && TREE_PURPOSE (constructor_elements) == field)
5691         return TREE_VALUE (constructor_elements);
5692     }
5693   return 0;
5694 }
5695
5696 /* "Output" the next constructor element.
5697    At top level, really output it to assembler code now.
5698    Otherwise, collect it in a list from which we will make a CONSTRUCTOR.
5699    TYPE is the data type that the containing data type wants here.
5700    FIELD is the field (a FIELD_DECL) or the index that this element fills.
5701    If VALUE is a string constant, STRICT_STRING is true if it is
5702    unparenthesized or we should not warn here for it being parenthesized.
5703    For other types of VALUE, STRICT_STRING is not used.
5704
5705    PENDING if non-nil means output pending elements that belong
5706    right after this element.  (PENDING is normally 1;
5707    it is 0 while outputting pending elements, to avoid recursion.)  */
5708
5709 static void
5710 output_init_element (tree value, bool strict_string, tree type, tree field,
5711                      int pending)
5712 {
5713   if (type == error_mark_node || value == error_mark_node)
5714     {
5715       constructor_erroneous = 1;
5716       return;
5717     }
5718   if (TREE_CODE (TREE_TYPE (value)) == FUNCTION_TYPE
5719       || (TREE_CODE (TREE_TYPE (value)) == ARRAY_TYPE
5720           && !(TREE_CODE (value) == STRING_CST
5721                && TREE_CODE (type) == ARRAY_TYPE
5722                && INTEGRAL_TYPE_P (TREE_TYPE (type)))
5723           && !comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (value)),
5724                          TYPE_MAIN_VARIANT (type))))
5725     value = default_conversion (value);
5726
5727   if (TREE_CODE (value) == COMPOUND_LITERAL_EXPR
5728       && require_constant_value && !flag_isoc99 && pending)
5729     {
5730       /* As an extension, allow initializing objects with static storage
5731          duration with compound literals (which are then treated just as
5732          the brace enclosed list they contain).  */
5733       tree decl = COMPOUND_LITERAL_EXPR_DECL (value);
5734       value = DECL_INITIAL (decl);
5735     }
5736
5737   if (value == error_mark_node)
5738     constructor_erroneous = 1;
5739   else if (!TREE_CONSTANT (value))
5740     constructor_constant = 0;
5741   else if (!initializer_constant_valid_p (value, TREE_TYPE (value))
5742            || ((TREE_CODE (constructor_type) == RECORD_TYPE
5743                 || TREE_CODE (constructor_type) == UNION_TYPE)
5744                && DECL_C_BIT_FIELD (field)
5745                && TREE_CODE (value) != INTEGER_CST))
5746     constructor_simple = 0;
5747
5748   if (!initializer_constant_valid_p (value, TREE_TYPE (value)))
5749     {
5750       if (require_constant_value)
5751         {
5752           error_init ("initializer element is not constant");
5753           value = error_mark_node;
5754         }
5755       else if (require_constant_elements)
5756         pedwarn ("initializer element is not computable at load time");
5757     }
5758
5759   /* If this field is empty (and not at the end of structure),
5760      don't do anything other than checking the initializer.  */
5761   if (field
5762       && (TREE_TYPE (field) == error_mark_node
5763           || (COMPLETE_TYPE_P (TREE_TYPE (field))
5764               && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))
5765               && (TREE_CODE (constructor_type) == ARRAY_TYPE
5766                   || TREE_CHAIN (field)))))
5767     return;
5768
5769   value = digest_init (type, value, strict_string, require_constant_value);
5770   if (value == error_mark_node)
5771     {
5772       constructor_erroneous = 1;
5773       return;
5774     }
5775
5776   /* If this element doesn't come next in sequence,
5777      put it on constructor_pending_elts.  */
5778   if (TREE_CODE (constructor_type) == ARRAY_TYPE
5779       && (!constructor_incremental
5780           || !tree_int_cst_equal (field, constructor_unfilled_index)))
5781     {
5782       if (constructor_incremental
5783           && tree_int_cst_lt (field, constructor_unfilled_index))
5784         set_nonincremental_init ();
5785
5786       add_pending_init (field, value);
5787       return;
5788     }
5789   else if (TREE_CODE (constructor_type) == RECORD_TYPE
5790            && (!constructor_incremental
5791                || field != constructor_unfilled_fields))
5792     {
5793       /* We do this for records but not for unions.  In a union,
5794          no matter which field is specified, it can be initialized
5795          right away since it starts at the beginning of the union.  */
5796       if (constructor_incremental)
5797         {
5798           if (!constructor_unfilled_fields)
5799             set_nonincremental_init ();
5800           else
5801             {
5802               tree bitpos, unfillpos;
5803
5804               bitpos = bit_position (field);
5805               unfillpos = bit_position (constructor_unfilled_fields);
5806
5807               if (tree_int_cst_lt (bitpos, unfillpos))
5808                 set_nonincremental_init ();
5809             }
5810         }
5811
5812       add_pending_init (field, value);
5813       return;
5814     }
5815   else if (TREE_CODE (constructor_type) == UNION_TYPE
5816            && constructor_elements)
5817     {
5818       if (TREE_SIDE_EFFECTS (TREE_VALUE (constructor_elements)))
5819         warning_init ("initialized field with side-effects overwritten");
5820
5821       /* We can have just one union field set.  */
5822       constructor_elements = 0;
5823     }
5824
5825   /* Otherwise, output this element either to
5826      constructor_elements or to the assembler file.  */
5827
5828   if (field && TREE_CODE (field) == INTEGER_CST)
5829     field = copy_node (field);
5830   constructor_elements
5831     = tree_cons (field, value, constructor_elements);
5832
5833   /* Advance the variable that indicates sequential elements output.  */
5834   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5835     constructor_unfilled_index
5836       = size_binop (PLUS_EXPR, constructor_unfilled_index,
5837                     bitsize_one_node);
5838   else if (TREE_CODE (constructor_type) == RECORD_TYPE)
5839     {
5840       constructor_unfilled_fields
5841         = TREE_CHAIN (constructor_unfilled_fields);
5842
5843       /* Skip any nameless bit fields.  */
5844       while (constructor_unfilled_fields != 0
5845              && DECL_C_BIT_FIELD (constructor_unfilled_fields)
5846              && DECL_NAME (constructor_unfilled_fields) == 0)
5847         constructor_unfilled_fields =
5848           TREE_CHAIN (constructor_unfilled_fields);
5849     }
5850   else if (TREE_CODE (constructor_type) == UNION_TYPE)
5851     constructor_unfilled_fields = 0;
5852
5853   /* Now output any pending elements which have become next.  */
5854   if (pending)
5855     output_pending_init_elements (0);
5856 }
5857
5858 /* Output any pending elements which have become next.
5859    As we output elements, constructor_unfilled_{fields,index}
5860    advances, which may cause other elements to become next;
5861    if so, they too are output.
5862
5863    If ALL is 0, we return when there are
5864    no more pending elements to output now.
5865
5866    If ALL is 1, we output space as necessary so that
5867    we can output all the pending elements.  */
5868
5869 static void
5870 output_pending_init_elements (int all)
5871 {
5872   struct init_node *elt = constructor_pending_elts;
5873   tree next;
5874
5875  retry:
5876
5877   /* Look through the whole pending tree.
5878      If we find an element that should be output now,
5879      output it.  Otherwise, set NEXT to the element
5880      that comes first among those still pending.  */
5881
5882   next = 0;
5883   while (elt)
5884     {
5885       if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5886         {
5887           if (tree_int_cst_equal (elt->purpose,
5888                                   constructor_unfilled_index))
5889             output_init_element (elt->value, true,
5890                                  TREE_TYPE (constructor_type),
5891                                  constructor_unfilled_index, 0);
5892           else if (tree_int_cst_lt (constructor_unfilled_index,
5893                                     elt->purpose))
5894             {
5895               /* Advance to the next smaller node.  */
5896               if (elt->left)
5897                 elt = elt->left;
5898               else
5899                 {
5900                   /* We have reached the smallest node bigger than the
5901                      current unfilled index.  Fill the space first.  */
5902                   next = elt->purpose;
5903                   break;
5904                 }
5905             }
5906           else
5907             {
5908               /* Advance to the next bigger node.  */
5909               if (elt->right)
5910                 elt = elt->right;
5911               else
5912                 {
5913                   /* We have reached the biggest node in a subtree.  Find
5914                      the parent of it, which is the next bigger node.  */
5915                   while (elt->parent && elt->parent->right == elt)
5916                     elt = elt->parent;
5917                   elt = elt->parent;
5918                   if (elt && tree_int_cst_lt (constructor_unfilled_index,
5919                                               elt->purpose))
5920                     {
5921                       next = elt->purpose;
5922                       break;
5923                     }
5924                 }
5925             }
5926         }
5927       else if (TREE_CODE (constructor_type) == RECORD_TYPE
5928                || TREE_CODE (constructor_type) == UNION_TYPE)
5929         {
5930           tree ctor_unfilled_bitpos, elt_bitpos;
5931
5932           /* If the current record is complete we are done.  */
5933           if (constructor_unfilled_fields == 0)
5934             break;
5935
5936           ctor_unfilled_bitpos = bit_position (constructor_unfilled_fields);
5937           elt_bitpos = bit_position (elt->purpose);
5938           /* We can't compare fields here because there might be empty
5939              fields in between.  */
5940           if (tree_int_cst_equal (elt_bitpos, ctor_unfilled_bitpos))
5941             {
5942               constructor_unfilled_fields = elt->purpose;
5943               output_init_element (elt->value, true, TREE_TYPE (elt->purpose),
5944                                    elt->purpose, 0);
5945             }
5946           else if (tree_int_cst_lt (ctor_unfilled_bitpos, elt_bitpos))
5947             {
5948               /* Advance to the next smaller node.  */
5949               if (elt->left)
5950                 elt = elt->left;
5951               else
5952                 {
5953                   /* We have reached the smallest node bigger than the
5954                      current unfilled field.  Fill the space first.  */
5955                   next = elt->purpose;
5956                   break;
5957                 }
5958             }
5959           else
5960             {
5961               /* Advance to the next bigger node.  */
5962               if (elt->right)
5963                 elt = elt->right;
5964               else
5965                 {
5966                   /* We have reached the biggest node in a subtree.  Find
5967                      the parent of it, which is the next bigger node.  */
5968                   while (elt->parent && elt->parent->right == elt)
5969                     elt = elt->parent;
5970                   elt = elt->parent;
5971                   if (elt
5972                       && (tree_int_cst_lt (ctor_unfilled_bitpos,
5973                                            bit_position (elt->purpose))))
5974                     {
5975                       next = elt->purpose;
5976                       break;
5977                     }
5978                 }
5979             }
5980         }
5981     }
5982
5983   /* Ordinarily return, but not if we want to output all
5984      and there are elements left.  */
5985   if (!(all && next != 0))
5986     return;
5987
5988   /* If it's not incremental, just skip over the gap, so that after
5989      jumping to retry we will output the next successive element.  */
5990   if (TREE_CODE (constructor_type) == RECORD_TYPE
5991       || TREE_CODE (constructor_type) == UNION_TYPE)
5992     constructor_unfilled_fields = next;
5993   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5994     constructor_unfilled_index = next;
5995
5996   /* ELT now points to the node in the pending tree with the next
5997      initializer to output.  */
5998   goto retry;
5999 }
6000 \f
6001 /* Add one non-braced element to the current constructor level.
6002    This adjusts the current position within the constructor's type.
6003    This may also start or terminate implicit levels
6004    to handle a partly-braced initializer.
6005
6006    Once this has found the correct level for the new element,
6007    it calls output_init_element.  */
6008
6009 void
6010 process_init_element (struct c_expr value)
6011 {
6012   tree orig_value = value.value;
6013   int string_flag = orig_value != 0 && TREE_CODE (orig_value) == STRING_CST;
6014   bool strict_string = value.original_code == STRING_CST;
6015
6016   designator_depth = 0;
6017   designator_errorneous = 0;
6018
6019   /* Handle superfluous braces around string cst as in
6020      char x[] = {"foo"}; */
6021   if (string_flag
6022       && constructor_type
6023       && TREE_CODE (constructor_type) == ARRAY_TYPE
6024       && INTEGRAL_TYPE_P (TREE_TYPE (constructor_type))
6025       && integer_zerop (constructor_unfilled_index))
6026     {
6027       if (constructor_stack->replacement_value.value)
6028         error_init ("excess elements in char array initializer");
6029       constructor_stack->replacement_value = value;
6030       return;
6031     }
6032
6033   if (constructor_stack->replacement_value.value != 0)
6034     {
6035       error_init ("excess elements in struct initializer");
6036       return;
6037     }
6038
6039   /* Ignore elements of a brace group if it is entirely superfluous
6040      and has already been diagnosed.  */
6041   if (constructor_type == 0)
6042     return;
6043
6044   /* If we've exhausted any levels that didn't have braces,
6045      pop them now.  */
6046   while (constructor_stack->implicit)
6047     {
6048       if ((TREE_CODE (constructor_type) == RECORD_TYPE
6049            || TREE_CODE (constructor_type) == UNION_TYPE)
6050           && constructor_fields == 0)
6051         process_init_element (pop_init_level (1));
6052       else if (TREE_CODE (constructor_type) == ARRAY_TYPE
6053                && (constructor_max_index == 0
6054                    || tree_int_cst_lt (constructor_max_index,
6055                                        constructor_index)))
6056         process_init_element (pop_init_level (1));
6057       else
6058         break;
6059     }
6060
6061   /* In the case of [LO ... HI] = VALUE, only evaluate VALUE once.  */
6062   if (constructor_range_stack)
6063     {
6064       /* If value is a compound literal and we'll be just using its
6065          content, don't put it into a SAVE_EXPR.  */
6066       if (TREE_CODE (value.value) != COMPOUND_LITERAL_EXPR
6067           || !require_constant_value
6068           || flag_isoc99)
6069         value.value = save_expr (value.value);
6070     }
6071
6072   while (1)
6073     {
6074       if (TREE_CODE (constructor_type) == RECORD_TYPE)
6075         {
6076           tree fieldtype;
6077           enum tree_code fieldcode;
6078
6079           if (constructor_fields == 0)
6080             {
6081               pedwarn_init ("excess elements in struct initializer");
6082               break;
6083             }
6084
6085           fieldtype = TREE_TYPE (constructor_fields);
6086           if (fieldtype != error_mark_node)
6087             fieldtype = TYPE_MAIN_VARIANT (fieldtype);
6088           fieldcode = TREE_CODE (fieldtype);
6089
6090           /* Error for non-static initialization of a flexible array member.  */
6091           if (fieldcode == ARRAY_TYPE
6092               && !require_constant_value
6093               && TYPE_SIZE (fieldtype) == NULL_TREE
6094               && TREE_CHAIN (constructor_fields) == NULL_TREE)
6095             {
6096               error_init ("non-static initialization of a flexible array member");
6097               break;
6098             }
6099
6100           /* Accept a string constant to initialize a subarray.  */
6101           if (value.value != 0
6102               && fieldcode == ARRAY_TYPE
6103               && INTEGRAL_TYPE_P (TREE_TYPE (fieldtype))
6104               && string_flag)
6105             value.value = orig_value;
6106           /* Otherwise, if we have come to a subaggregate,
6107              and we don't have an element of its type, push into it.  */
6108           else if (value.value != 0
6109                    && value.value != error_mark_node
6110                    && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != fieldtype
6111                    && (fieldcode == RECORD_TYPE || fieldcode == ARRAY_TYPE
6112                        || fieldcode == UNION_TYPE))
6113             {
6114               push_init_level (1);
6115               continue;
6116             }
6117
6118           if (value.value)
6119             {
6120               push_member_name (constructor_fields);
6121               output_init_element (value.value, strict_string,
6122                                    fieldtype, constructor_fields, 1);
6123               RESTORE_SPELLING_DEPTH (constructor_depth);
6124             }
6125           else
6126             /* Do the bookkeeping for an element that was
6127                directly output as a constructor.  */
6128             {
6129               /* For a record, keep track of end position of last field.  */
6130               if (DECL_SIZE (constructor_fields))
6131                 constructor_bit_index
6132                   = size_binop (PLUS_EXPR,
6133                                 bit_position (constructor_fields),
6134                                 DECL_SIZE (constructor_fields));
6135
6136               /* If the current field was the first one not yet written out,
6137                  it isn't now, so update.  */
6138               if (constructor_unfilled_fields == constructor_fields)
6139                 {
6140                   constructor_unfilled_fields = TREE_CHAIN (constructor_fields);
6141                   /* Skip any nameless bit fields.  */
6142                   while (constructor_unfilled_fields != 0
6143                          && DECL_C_BIT_FIELD (constructor_unfilled_fields)
6144                          && DECL_NAME (constructor_unfilled_fields) == 0)
6145                     constructor_unfilled_fields =
6146                       TREE_CHAIN (constructor_unfilled_fields);
6147                 }
6148             }
6149
6150           constructor_fields = TREE_CHAIN (constructor_fields);
6151           /* Skip any nameless bit fields at the beginning.  */
6152           while (constructor_fields != 0
6153                  && DECL_C_BIT_FIELD (constructor_fields)
6154                  && DECL_NAME (constructor_fields) == 0)
6155             constructor_fields = TREE_CHAIN (constructor_fields);
6156         }
6157       else if (TREE_CODE (constructor_type) == UNION_TYPE)
6158         {
6159           tree fieldtype;
6160           enum tree_code fieldcode;
6161
6162           if (constructor_fields == 0)
6163             {
6164               pedwarn_init ("excess elements in union initializer");
6165               break;
6166             }
6167
6168           fieldtype = TREE_TYPE (constructor_fields);
6169           if (fieldtype != error_mark_node)
6170             fieldtype = TYPE_MAIN_VARIANT (fieldtype);
6171           fieldcode = TREE_CODE (fieldtype);
6172
6173           /* Warn that traditional C rejects initialization of unions.
6174              We skip the warning if the value is zero.  This is done
6175              under the assumption that the zero initializer in user
6176              code appears conditioned on e.g. __STDC__ to avoid
6177              "missing initializer" warnings and relies on default
6178              initialization to zero in the traditional C case.
6179              We also skip the warning if the initializer is designated,
6180              again on the assumption that this must be conditional on
6181              __STDC__ anyway (and we've already complained about the
6182              member-designator already).  */
6183           if (warn_traditional && !in_system_header && !constructor_designated
6184               && !(value.value && (integer_zerop (value.value)
6185                                    || real_zerop (value.value))))
6186             warning ("traditional C rejects initialization of unions");
6187
6188           /* Accept a string constant to initialize a subarray.  */
6189           if (value.value != 0
6190               && fieldcode == ARRAY_TYPE
6191               && INTEGRAL_TYPE_P (TREE_TYPE (fieldtype))
6192               && string_flag)
6193             value.value = orig_value;
6194           /* Otherwise, if we have come to a subaggregate,
6195              and we don't have an element of its type, push into it.  */
6196           else if (value.value != 0
6197                    && value.value != error_mark_node
6198                    && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != fieldtype
6199                    && (fieldcode == RECORD_TYPE || fieldcode == ARRAY_TYPE
6200                        || fieldcode == UNION_TYPE))
6201             {
6202               push_init_level (1);
6203               continue;
6204             }
6205
6206           if (value.value)
6207             {
6208               push_member_name (constructor_fields);
6209               output_init_element (value.value, strict_string,
6210                                    fieldtype, constructor_fields, 1);
6211               RESTORE_SPELLING_DEPTH (constructor_depth);
6212             }
6213           else
6214             /* Do the bookkeeping for an element that was
6215                directly output as a constructor.  */
6216             {
6217               constructor_bit_index = DECL_SIZE (constructor_fields);
6218               constructor_unfilled_fields = TREE_CHAIN (constructor_fields);
6219             }
6220
6221           constructor_fields = 0;
6222         }
6223       else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6224         {
6225           tree elttype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
6226           enum tree_code eltcode = TREE_CODE (elttype);
6227
6228           /* Accept a string constant to initialize a subarray.  */
6229           if (value.value != 0
6230               && eltcode == ARRAY_TYPE
6231               && INTEGRAL_TYPE_P (TREE_TYPE (elttype))
6232               && string_flag)
6233             value.value = orig_value;
6234           /* Otherwise, if we have come to a subaggregate,
6235              and we don't have an element of its type, push into it.  */
6236           else if (value.value != 0
6237                    && value.value != error_mark_node
6238                    && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != elttype
6239                    && (eltcode == RECORD_TYPE || eltcode == ARRAY_TYPE
6240                        || eltcode == UNION_TYPE))
6241             {
6242               push_init_level (1);
6243               continue;
6244             }
6245
6246           if (constructor_max_index != 0
6247               && (tree_int_cst_lt (constructor_max_index, constructor_index)
6248                   || integer_all_onesp (constructor_max_index)))
6249             {
6250               pedwarn_init ("excess elements in array initializer");
6251               break;
6252             }
6253
6254           /* Now output the actual element.  */
6255           if (value.value)
6256             {
6257               push_array_bounds (tree_low_cst (constructor_index, 0));
6258               output_init_element (value.value, strict_string,
6259                                    elttype, constructor_index, 1);
6260               RESTORE_SPELLING_DEPTH (constructor_depth);
6261             }
6262
6263           constructor_index
6264             = size_binop (PLUS_EXPR, constructor_index, bitsize_one_node);
6265
6266           if (!value.value)
6267             /* If we are doing the bookkeeping for an element that was
6268                directly output as a constructor, we must update
6269                constructor_unfilled_index.  */
6270             constructor_unfilled_index = constructor_index;
6271         }
6272       else if (TREE_CODE (constructor_type) == VECTOR_TYPE)
6273         {
6274           tree elttype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
6275
6276          /* Do a basic check of initializer size.  Note that vectors
6277             always have a fixed size derived from their type.  */
6278           if (tree_int_cst_lt (constructor_max_index, constructor_index))
6279             {
6280               pedwarn_init ("excess elements in vector initializer");
6281               break;
6282             }
6283
6284           /* Now output the actual element.  */
6285           if (value.value)
6286             output_init_element (value.value, strict_string,
6287                                  elttype, constructor_index, 1);
6288
6289           constructor_index
6290             = size_binop (PLUS_EXPR, constructor_index, bitsize_one_node);
6291
6292           if (!value.value)
6293             /* If we are doing the bookkeeping for an element that was
6294                directly output as a constructor, we must update
6295                constructor_unfilled_index.  */
6296             constructor_unfilled_index = constructor_index;
6297         }
6298
6299       /* Handle the sole element allowed in a braced initializer
6300          for a scalar variable.  */
6301       else if (constructor_type != error_mark_node
6302                && constructor_fields == 0)
6303         {
6304           pedwarn_init ("excess elements in scalar initializer");
6305           break;
6306         }
6307       else
6308         {
6309           if (value.value)
6310             output_init_element (value.value, strict_string,
6311                                  constructor_type, NULL_TREE, 1);
6312           constructor_fields = 0;
6313         }
6314
6315       /* Handle range initializers either at this level or anywhere higher
6316          in the designator stack.  */
6317       if (constructor_range_stack)
6318         {
6319           struct constructor_range_stack *p, *range_stack;
6320           int finish = 0;
6321
6322           range_stack = constructor_range_stack;
6323           constructor_range_stack = 0;
6324           while (constructor_stack != range_stack->stack)
6325             {
6326               gcc_assert (constructor_stack->implicit);
6327               process_init_element (pop_init_level (1));
6328             }
6329           for (p = range_stack;
6330                !p->range_end || tree_int_cst_equal (p->index, p->range_end);
6331                p = p->prev)
6332             {
6333               gcc_assert (constructor_stack->implicit);
6334               process_init_element (pop_init_level (1));
6335             }
6336
6337           p->index = size_binop (PLUS_EXPR, p->index, bitsize_one_node);
6338           if (tree_int_cst_equal (p->index, p->range_end) && !p->prev)
6339             finish = 1;
6340
6341           while (1)
6342             {
6343               constructor_index = p->index;
6344               constructor_fields = p->fields;
6345               if (finish && p->range_end && p->index == p->range_start)
6346                 {
6347                   finish = 0;
6348                   p->prev = 0;
6349                 }
6350               p = p->next;
6351               if (!p)
6352                 break;
6353               push_init_level (2);
6354               p->stack = constructor_stack;
6355               if (p->range_end && tree_int_cst_equal (p->index, p->range_end))
6356                 p->index = p->range_start;
6357             }
6358
6359           if (!finish)
6360             constructor_range_stack = range_stack;
6361           continue;
6362         }
6363
6364       break;
6365     }
6366
6367   constructor_range_stack = 0;
6368 }
6369 \f
6370 /* Build a complete asm-statement, whose components are a CV_QUALIFIER
6371    (guaranteed to be 'volatile' or null) and ARGS (represented using
6372    an ASM_EXPR node).  */
6373 tree
6374 build_asm_stmt (tree cv_qualifier, tree args)
6375 {
6376   if (!ASM_VOLATILE_P (args) && cv_qualifier)
6377     ASM_VOLATILE_P (args) = 1;
6378   return add_stmt (args);
6379 }
6380
6381 /* Build an asm-expr, whose components are a STRING, some OUTPUTS,
6382    some INPUTS, and some CLOBBERS.  The latter three may be NULL.
6383    SIMPLE indicates whether there was anything at all after the
6384    string in the asm expression -- asm("blah") and asm("blah" : )
6385    are subtly different.  We use a ASM_EXPR node to represent this.  */
6386 tree
6387 build_asm_expr (tree string, tree outputs, tree inputs, tree clobbers,
6388                 bool simple)
6389 {
6390   tree tail;
6391   tree args;
6392   int i;
6393   const char *constraint;
6394   const char **oconstraints;
6395   bool allows_mem, allows_reg, is_inout;
6396   int ninputs, noutputs;
6397
6398   ninputs = list_length (inputs);
6399   noutputs = list_length (outputs);
6400   oconstraints = (const char **) alloca (noutputs * sizeof (const char *));
6401
6402   string = resolve_asm_operand_names (string, outputs, inputs);
6403
6404   /* Remove output conversions that change the type but not the mode.  */
6405   for (i = 0, tail = outputs; tail; ++i, tail = TREE_CHAIN (tail))
6406     {
6407       tree output = TREE_VALUE (tail);
6408
6409       /* ??? Really, this should not be here.  Users should be using a
6410          proper lvalue, dammit.  But there's a long history of using casts
6411          in the output operands.  In cases like longlong.h, this becomes a
6412          primitive form of typechecking -- if the cast can be removed, then
6413          the output operand had a type of the proper width; otherwise we'll
6414          get an error.  Gross, but ...  */
6415       STRIP_NOPS (output);
6416
6417       if (!lvalue_or_else (output, lv_asm))
6418         output = error_mark_node;
6419
6420       constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tail)));
6421       oconstraints[i] = constraint;
6422
6423       if (parse_output_constraint (&constraint, i, ninputs, noutputs,
6424                                    &allows_mem, &allows_reg, &is_inout))
6425         {
6426           /* If the operand is going to end up in memory,
6427              mark it addressable.  */
6428           if (!allows_reg && !c_mark_addressable (output))
6429             output = error_mark_node;
6430         }
6431       else
6432         output = error_mark_node;
6433
6434       TREE_VALUE (tail) = output;
6435     }
6436
6437   /* Perform default conversions on array and function inputs.
6438      Don't do this for other types as it would screw up operands
6439      expected to be in memory.  */
6440   for (i = 0, tail = inputs; tail; ++i, tail = TREE_CHAIN (tail))
6441     {
6442       tree input;
6443
6444       constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tail)));
6445       input = TREE_VALUE (tail);
6446
6447       input = default_function_array_conversion (input);
6448
6449       if (parse_input_constraint (&constraint, i, ninputs, noutputs, 0,
6450                                   oconstraints, &allows_mem, &allows_reg))
6451         {
6452           /* If the operand is going to end up in memory,
6453              mark it addressable.  */
6454           if (!allows_reg && allows_mem)
6455             {
6456               /* Strip the nops as we allow this case.  FIXME, this really
6457                  should be rejected or made deprecated.  */
6458               STRIP_NOPS (input);
6459               if (!c_mark_addressable (input))
6460                 input = error_mark_node;
6461           }
6462         }
6463       else
6464         input = error_mark_node;
6465
6466       TREE_VALUE (tail) = input;
6467     }
6468
6469   args = build_stmt (ASM_EXPR, string, outputs, inputs, clobbers);
6470
6471   /* Simple asm statements are treated as volatile.  */
6472   if (simple)
6473     {
6474       ASM_VOLATILE_P (args) = 1;
6475       ASM_INPUT_P (args) = 1;
6476     }
6477
6478   return args;
6479 }
6480 \f
6481 /* Generate a goto statement to LABEL.  */
6482
6483 tree
6484 c_finish_goto_label (tree label)
6485 {
6486   tree decl = lookup_label (label);
6487   if (!decl)
6488     return NULL_TREE;
6489
6490   if (C_DECL_UNJUMPABLE_STMT_EXPR (decl))
6491     {
6492       error ("jump into statement expression");
6493       return NULL_TREE;
6494     }
6495
6496   if (!C_DECL_UNDEFINABLE_STMT_EXPR (decl))
6497     {
6498       /* No jump from outside this statement expression context, so
6499          record that there is a jump from within this context.  */
6500       struct c_label_list *nlist;
6501       nlist = XOBNEW (&parser_obstack, struct c_label_list);
6502       nlist->next = label_context_stack->labels_used;
6503       nlist->label = decl;
6504       label_context_stack->labels_used = nlist;
6505     }
6506
6507   TREE_USED (decl) = 1;
6508   return add_stmt (build1 (GOTO_EXPR, void_type_node, decl));
6509 }
6510
6511 /* Generate a computed goto statement to EXPR.  */
6512
6513 tree
6514 c_finish_goto_ptr (tree expr)
6515 {
6516   if (pedantic)
6517     pedwarn ("ISO C forbids %<goto *expr;%>");
6518   expr = convert (ptr_type_node, expr);
6519   return add_stmt (build1 (GOTO_EXPR, void_type_node, expr));
6520 }
6521
6522 /* Generate a C `return' statement.  RETVAL is the expression for what
6523    to return, or a null pointer for `return;' with no value.  */
6524
6525 tree
6526 c_finish_return (tree retval)
6527 {
6528   tree valtype = TREE_TYPE (TREE_TYPE (current_function_decl));
6529
6530   if (TREE_THIS_VOLATILE (current_function_decl))
6531     warning ("function declared %<noreturn%> has a %<return%> statement");
6532
6533   if (!retval)
6534     {
6535       current_function_returns_null = 1;
6536       if ((warn_return_type || flag_isoc99)
6537           && valtype != 0 && TREE_CODE (valtype) != VOID_TYPE)
6538         pedwarn_c99 ("%<return%> with no value, in "
6539                      "function returning non-void");
6540     }
6541   else if (valtype == 0 || TREE_CODE (valtype) == VOID_TYPE)
6542     {
6543       current_function_returns_null = 1;
6544       if (pedantic || TREE_CODE (TREE_TYPE (retval)) != VOID_TYPE)
6545         pedwarn ("%<return%> with a value, in function returning void");
6546     }
6547   else
6548     {
6549       tree t = convert_for_assignment (valtype, retval, ic_return,
6550                                        NULL_TREE, NULL_TREE, 0);
6551       tree res = DECL_RESULT (current_function_decl);
6552       tree inner;
6553
6554       current_function_returns_value = 1;
6555       if (t == error_mark_node)
6556         return NULL_TREE;
6557
6558       inner = t = convert (TREE_TYPE (res), t);
6559
6560       /* Strip any conversions, additions, and subtractions, and see if
6561          we are returning the address of a local variable.  Warn if so.  */
6562       while (1)
6563         {
6564           switch (TREE_CODE (inner))
6565             {
6566             case NOP_EXPR:   case NON_LVALUE_EXPR:  case CONVERT_EXPR:
6567             case PLUS_EXPR:
6568               inner = TREE_OPERAND (inner, 0);
6569               continue;
6570
6571             case MINUS_EXPR:
6572               /* If the second operand of the MINUS_EXPR has a pointer
6573                  type (or is converted from it), this may be valid, so
6574                  don't give a warning.  */
6575               {
6576                 tree op1 = TREE_OPERAND (inner, 1);
6577
6578                 while (!POINTER_TYPE_P (TREE_TYPE (op1))
6579                        && (TREE_CODE (op1) == NOP_EXPR
6580                            || TREE_CODE (op1) == NON_LVALUE_EXPR
6581                            || TREE_CODE (op1) == CONVERT_EXPR))
6582                   op1 = TREE_OPERAND (op1, 0);
6583
6584                 if (POINTER_TYPE_P (TREE_TYPE (op1)))
6585                   break;
6586
6587                 inner = TREE_OPERAND (inner, 0);
6588                 continue;
6589               }
6590
6591             case ADDR_EXPR:
6592               inner = TREE_OPERAND (inner, 0);
6593
6594               while (REFERENCE_CLASS_P (inner)
6595                      && TREE_CODE (inner) != INDIRECT_REF)
6596                 inner = TREE_OPERAND (inner, 0);
6597
6598               if (DECL_P (inner)
6599                   && !DECL_EXTERNAL (inner)
6600                   && !TREE_STATIC (inner)
6601                   && DECL_CONTEXT (inner) == current_function_decl)
6602                 warning ("function returns address of local variable");
6603               break;
6604
6605             default:
6606               break;
6607             }
6608
6609           break;
6610         }
6611
6612       retval = build2 (MODIFY_EXPR, TREE_TYPE (res), res, t);
6613     }
6614
6615   return add_stmt (build_stmt (RETURN_EXPR, retval));
6616 }
6617 \f
6618 struct c_switch {
6619   /* The SWITCH_EXPR being built.  */
6620   tree switch_expr;
6621
6622   /* The original type of the testing expression, i.e. before the
6623      default conversion is applied.  */
6624   tree orig_type;
6625
6626   /* A splay-tree mapping the low element of a case range to the high
6627      element, or NULL_TREE if there is no high element.  Used to
6628      determine whether or not a new case label duplicates an old case
6629      label.  We need a tree, rather than simply a hash table, because
6630      of the GNU case range extension.  */
6631   splay_tree cases;
6632
6633   /* Number of nested statement expressions within this switch
6634      statement; if nonzero, case and default labels may not
6635      appear.  */
6636   unsigned int blocked_stmt_expr;
6637
6638   /* The next node on the stack.  */
6639   struct c_switch *next;
6640 };
6641
6642 /* A stack of the currently active switch statements.  The innermost
6643    switch statement is on the top of the stack.  There is no need to
6644    mark the stack for garbage collection because it is only active
6645    during the processing of the body of a function, and we never
6646    collect at that point.  */
6647
6648 struct c_switch *c_switch_stack;
6649
6650 /* Start a C switch statement, testing expression EXP.  Return the new
6651    SWITCH_EXPR.  */
6652
6653 tree
6654 c_start_case (tree exp)
6655 {
6656   enum tree_code code;
6657   tree type, orig_type = error_mark_node;
6658   struct c_switch *cs;
6659
6660   if (exp != error_mark_node)
6661     {
6662       code = TREE_CODE (TREE_TYPE (exp));
6663       orig_type = TREE_TYPE (exp);
6664
6665       if (!INTEGRAL_TYPE_P (orig_type)
6666           && code != ERROR_MARK)
6667         {
6668           error ("switch quantity not an integer");
6669           exp = integer_zero_node;
6670           orig_type = error_mark_node;
6671         }
6672       else
6673         {
6674           type = TYPE_MAIN_VARIANT (TREE_TYPE (exp));
6675
6676           if (warn_traditional && !in_system_header
6677               && (type == long_integer_type_node
6678                   || type == long_unsigned_type_node))
6679             warning ("%<long%> switch expression not converted to "
6680                      "%<int%> in ISO C");
6681
6682           exp = default_conversion (exp);
6683           type = TREE_TYPE (exp);
6684         }
6685     }
6686
6687   /* Add this new SWITCH_EXPR to the stack.  */
6688   cs = XNEW (struct c_switch);
6689   cs->switch_expr = build3 (SWITCH_EXPR, orig_type, exp, NULL_TREE, NULL_TREE);
6690   cs->orig_type = orig_type;
6691   cs->cases = splay_tree_new (case_compare, NULL, NULL);
6692   cs->blocked_stmt_expr = 0;
6693   cs->next = c_switch_stack;
6694   c_switch_stack = cs;
6695
6696   return add_stmt (cs->switch_expr);
6697 }
6698
6699 /* Process a case label.  */
6700
6701 tree
6702 do_case (tree low_value, tree high_value)
6703 {
6704   tree label = NULL_TREE;
6705
6706   if (c_switch_stack && !c_switch_stack->blocked_stmt_expr)
6707     {
6708       label = c_add_case_label (c_switch_stack->cases,
6709                                 SWITCH_COND (c_switch_stack->switch_expr),
6710                                 c_switch_stack->orig_type,
6711                                 low_value, high_value);
6712       if (label == error_mark_node)
6713         label = NULL_TREE;
6714     }
6715   else if (c_switch_stack && c_switch_stack->blocked_stmt_expr)
6716     {
6717       if (low_value)
6718         error ("case label in statement expression not containing "
6719                "enclosing switch statement");
6720       else
6721         error ("%<default%> label in statement expression not containing "
6722                "enclosing switch statement");
6723     }
6724   else if (low_value)
6725     error ("case label not within a switch statement");
6726   else
6727     error ("%<default%> label not within a switch statement");
6728
6729   return label;
6730 }
6731
6732 /* Finish the switch statement.  */
6733
6734 void
6735 c_finish_case (tree body)
6736 {
6737   struct c_switch *cs = c_switch_stack;
6738   location_t switch_location;
6739
6740   SWITCH_BODY (cs->switch_expr) = body;
6741
6742   gcc_assert (!cs->blocked_stmt_expr);
6743
6744   /* Emit warnings as needed.  */
6745   if (EXPR_HAS_LOCATION (cs->switch_expr))
6746     switch_location = EXPR_LOCATION (cs->switch_expr);
6747   else
6748     switch_location = input_location;
6749   c_do_switch_warnings (cs->cases, switch_location,
6750                         TREE_TYPE (cs->switch_expr),
6751                         SWITCH_COND (cs->switch_expr));
6752
6753   /* Pop the stack.  */
6754   c_switch_stack = cs->next;
6755   splay_tree_delete (cs->cases);
6756   XDELETE (cs);
6757 }
6758 \f
6759 /* Emit an if statement.  IF_LOCUS is the location of the 'if'.  COND,
6760    THEN_BLOCK and ELSE_BLOCK are expressions to be used; ELSE_BLOCK
6761    may be null.  NESTED_IF is true if THEN_BLOCK contains another IF
6762    statement, and was not surrounded with parenthesis.  */
6763
6764 void
6765 c_finish_if_stmt (location_t if_locus, tree cond, tree then_block,
6766                   tree else_block, bool nested_if)
6767 {
6768   tree stmt;
6769
6770   /* Diagnose an ambiguous else if if-then-else is nested inside if-then.  */
6771   if (warn_parentheses && nested_if && else_block == NULL)
6772     {
6773       tree inner_if = then_block;
6774
6775       /* We know from the grammar productions that there is an IF nested
6776          within THEN_BLOCK.  Due to labels and c99 conditional declarations,
6777          it might not be exactly THEN_BLOCK, but should be the last
6778          non-container statement within.  */
6779       while (1)
6780         switch (TREE_CODE (inner_if))
6781           {
6782           case COND_EXPR:
6783             goto found;
6784           case BIND_EXPR:
6785             inner_if = BIND_EXPR_BODY (inner_if);
6786             break;
6787           case STATEMENT_LIST:
6788             inner_if = expr_last (then_block);
6789             break;
6790           case TRY_FINALLY_EXPR:
6791           case TRY_CATCH_EXPR:
6792             inner_if = TREE_OPERAND (inner_if, 0);
6793             break;
6794           default:
6795             gcc_unreachable ();
6796           }
6797     found:
6798
6799       if (COND_EXPR_ELSE (inner_if))
6800          warning ("%Hsuggest explicit braces to avoid ambiguous %<else%>",
6801                   &if_locus);
6802     }
6803
6804   /* Diagnose ";" via the special empty statement node that we create.  */
6805   if (extra_warnings)
6806     {
6807       if (TREE_CODE (then_block) == NOP_EXPR && !TREE_TYPE (then_block))
6808         {
6809           if (!else_block)
6810             warning ("%Hempty body in an if-statement",
6811                      EXPR_LOCUS (then_block));
6812           then_block = alloc_stmt_list ();
6813         }
6814       if (else_block
6815           && TREE_CODE (else_block) == NOP_EXPR
6816           && !TREE_TYPE (else_block))
6817         {
6818           warning ("%Hempty body in an else-statement",
6819                    EXPR_LOCUS (else_block));
6820           else_block = alloc_stmt_list ();
6821         }
6822     }
6823
6824   stmt = build3 (COND_EXPR, NULL_TREE, cond, then_block, else_block);
6825   SET_EXPR_LOCATION (stmt, if_locus);
6826   add_stmt (stmt);
6827 }
6828
6829 /* Emit a general-purpose loop construct.  START_LOCUS is the location of
6830    the beginning of the loop.  COND is the loop condition.  COND_IS_FIRST
6831    is false for DO loops.  INCR is the FOR increment expression.  BODY is
6832    the statement controlled by the loop.  BLAB is the break label.  CLAB is
6833    the continue label.  Everything is allowed to be NULL.  */
6834
6835 void
6836 c_finish_loop (location_t start_locus, tree cond, tree incr, tree body,
6837                tree blab, tree clab, bool cond_is_first)
6838 {
6839   tree entry = NULL, exit = NULL, t;
6840
6841   /* If the condition is zero don't generate a loop construct.  */
6842   if (cond && integer_zerop (cond))
6843     {
6844       if (cond_is_first)
6845         {
6846           t = build_and_jump (&blab);
6847           SET_EXPR_LOCATION (t, start_locus);
6848           add_stmt (t);
6849         }
6850     }
6851   else
6852     {
6853       tree top = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
6854
6855       /* If we have an exit condition, then we build an IF with gotos either
6856          out of the loop, or to the top of it.  If there's no exit condition,
6857          then we just build a jump back to the top.  */
6858       exit = build_and_jump (&LABEL_EXPR_LABEL (top));
6859
6860       if (cond && !integer_nonzerop (cond))
6861         {
6862           /* Canonicalize the loop condition to the end.  This means
6863              generating a branch to the loop condition.  Reuse the
6864              continue label, if possible.  */
6865           if (cond_is_first)
6866             {
6867               if (incr || !clab)
6868                 {
6869                   entry = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
6870                   t = build_and_jump (&LABEL_EXPR_LABEL (entry));
6871                 }
6872               else
6873                 t = build1 (GOTO_EXPR, void_type_node, clab);
6874               SET_EXPR_LOCATION (t, start_locus);
6875               add_stmt (t);
6876             }
6877
6878           t = build_and_jump (&blab);
6879           exit = build3 (COND_EXPR, void_type_node, cond, exit, t);
6880           exit = fold (exit);
6881           if (cond_is_first)
6882             SET_EXPR_LOCATION (exit, start_locus);
6883           else
6884             SET_EXPR_LOCATION (exit, input_location);
6885         }
6886
6887       add_stmt (top);
6888     }
6889
6890   if (body)
6891     add_stmt (body);
6892   if (clab)
6893     add_stmt (build1 (LABEL_EXPR, void_type_node, clab));
6894   if (incr)
6895     add_stmt (incr);
6896   if (entry)
6897     add_stmt (entry);
6898   if (exit)
6899     add_stmt (exit);
6900   if (blab)
6901     add_stmt (build1 (LABEL_EXPR, void_type_node, blab));
6902 }
6903
6904 tree
6905 c_finish_bc_stmt (tree *label_p, bool is_break)
6906 {
6907   bool skip;
6908   tree label = *label_p;
6909
6910   /* In switch statements break is sometimes stylistically used after
6911      a return statement.  This can lead to spurious warnings about
6912      control reaching the end of a non-void function when it is
6913      inlined.  Note that we are calling block_may_fallthru with
6914      language specific tree nodes; this works because
6915      block_may_fallthru returns true when given something it does not
6916      understand.  */
6917   skip = !block_may_fallthru (cur_stmt_list);
6918
6919   if (!label)
6920     {
6921       if (!skip)
6922         *label_p = label = create_artificial_label ();
6923     }
6924   else if (TREE_CODE (label) != LABEL_DECL)
6925     {
6926       if (is_break)
6927         error ("break statement not within loop or switch");
6928       else
6929         error ("continue statement not within a loop");
6930       return NULL_TREE;
6931     }
6932
6933   if (skip)
6934     return NULL_TREE;
6935
6936   return add_stmt (build1 (GOTO_EXPR, void_type_node, label));
6937 }
6938
6939 /* A helper routine for c_process_expr_stmt and c_finish_stmt_expr.  */
6940
6941 static void
6942 emit_side_effect_warnings (tree expr)
6943 {
6944   if (expr == error_mark_node)
6945     ;
6946   else if (!TREE_SIDE_EFFECTS (expr))
6947     {
6948       if (!VOID_TYPE_P (TREE_TYPE (expr)) && !TREE_NO_WARNING (expr))
6949         warning ("%Hstatement with no effect",
6950                  EXPR_HAS_LOCATION (expr) ? EXPR_LOCUS (expr) : &input_location);
6951     }
6952   else if (warn_unused_value)
6953     warn_if_unused_value (expr, input_location);
6954 }
6955
6956 /* Process an expression as if it were a complete statement.  Emit
6957    diagnostics, but do not call ADD_STMT.  */
6958
6959 tree
6960 c_process_expr_stmt (tree expr)
6961 {
6962   if (!expr)
6963     return NULL_TREE;
6964
6965   /* Do default conversion if safe and possibly important,
6966      in case within ({...}).  */
6967   if ((TREE_CODE (TREE_TYPE (expr)) == ARRAY_TYPE
6968        && (flag_isoc99 || lvalue_p (expr)))
6969       || TREE_CODE (TREE_TYPE (expr)) == FUNCTION_TYPE)
6970     expr = default_conversion (expr);
6971
6972   if (warn_sequence_point)
6973     verify_sequence_points (expr);
6974
6975   if (TREE_TYPE (expr) != error_mark_node
6976       && !COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (expr))
6977       && TREE_CODE (TREE_TYPE (expr)) != ARRAY_TYPE)
6978     error ("expression statement has incomplete type");
6979
6980   /* If we're not processing a statement expression, warn about unused values.
6981      Warnings for statement expressions will be emitted later, once we figure
6982      out which is the result.  */
6983   if (!STATEMENT_LIST_STMT_EXPR (cur_stmt_list)
6984       && (extra_warnings || warn_unused_value))
6985     emit_side_effect_warnings (expr);
6986
6987   /* If the expression is not of a type to which we cannot assign a line
6988      number, wrap the thing in a no-op NOP_EXPR.  */
6989   if (DECL_P (expr) || CONSTANT_CLASS_P (expr))
6990     expr = build1 (NOP_EXPR, TREE_TYPE (expr), expr);
6991
6992   if (EXPR_P (expr))
6993     SET_EXPR_LOCATION (expr, input_location);
6994
6995   return expr;
6996 }
6997
6998 /* Emit an expression as a statement.  */
6999
7000 tree
7001 c_finish_expr_stmt (tree expr)
7002 {
7003   if (expr)
7004     return add_stmt (c_process_expr_stmt (expr));
7005   else
7006     return NULL;
7007 }
7008
7009 /* Do the opposite and emit a statement as an expression.  To begin,
7010    create a new binding level and return it.  */
7011
7012 tree
7013 c_begin_stmt_expr (void)
7014 {
7015   tree ret;
7016   struct c_label_context *nstack;
7017   struct c_label_list *glist;
7018
7019   /* We must force a BLOCK for this level so that, if it is not expanded
7020      later, there is a way to turn off the entire subtree of blocks that
7021      are contained in it.  */
7022   keep_next_level ();
7023   ret = c_begin_compound_stmt (true);
7024   if (c_switch_stack)
7025     {
7026       c_switch_stack->blocked_stmt_expr++;
7027       gcc_assert (c_switch_stack->blocked_stmt_expr != 0);
7028     }
7029   for (glist = label_context_stack->labels_used;
7030        glist != NULL;
7031        glist = glist->next)
7032     {
7033       C_DECL_UNDEFINABLE_STMT_EXPR (glist->label) = 1;
7034     }
7035   nstack = XOBNEW (&parser_obstack, struct c_label_context);
7036   nstack->labels_def = NULL;
7037   nstack->labels_used = NULL;
7038   nstack->next = label_context_stack;
7039   label_context_stack = nstack;
7040
7041   /* Mark the current statement list as belonging to a statement list.  */
7042   STATEMENT_LIST_STMT_EXPR (ret) = 1;
7043
7044   return ret;
7045 }
7046
7047 tree
7048 c_finish_stmt_expr (tree body)
7049 {
7050   tree last, type, tmp, val;
7051   tree *last_p;
7052   struct c_label_list *dlist, *glist, *glist_prev = NULL;
7053
7054   body = c_end_compound_stmt (body, true);
7055   if (c_switch_stack)
7056     {
7057       gcc_assert (c_switch_stack->blocked_stmt_expr != 0);
7058       c_switch_stack->blocked_stmt_expr--;
7059     }
7060   /* It is no longer possible to jump to labels defined within this
7061      statement expression.  */
7062   for (dlist = label_context_stack->labels_def;
7063        dlist != NULL;
7064        dlist = dlist->next)
7065     {
7066       C_DECL_UNJUMPABLE_STMT_EXPR (dlist->label) = 1;
7067     }
7068   /* It is again possible to define labels with a goto just outside
7069      this statement expression.  */
7070   for (glist = label_context_stack->next->labels_used;
7071        glist != NULL;
7072        glist = glist->next)
7073     {
7074       C_DECL_UNDEFINABLE_STMT_EXPR (glist->label) = 0;
7075       glist_prev = glist;
7076     }
7077   if (glist_prev != NULL)
7078     glist_prev->next = label_context_stack->labels_used;
7079   else
7080     label_context_stack->next->labels_used = label_context_stack->labels_used;
7081   label_context_stack = label_context_stack->next;
7082
7083   /* Locate the last statement in BODY.  See c_end_compound_stmt
7084      about always returning a BIND_EXPR.  */
7085   last_p = &BIND_EXPR_BODY (body);
7086   last = BIND_EXPR_BODY (body);
7087
7088  continue_searching:
7089   if (TREE_CODE (last) == STATEMENT_LIST)
7090     {
7091       tree_stmt_iterator i;
7092
7093       /* This can happen with degenerate cases like ({ }).  No value.  */
7094       if (!TREE_SIDE_EFFECTS (last))
7095         return body;
7096
7097       /* If we're supposed to generate side effects warnings, process
7098          all of the statements except the last.  */
7099       if (extra_warnings || warn_unused_value)
7100         {
7101           for (i = tsi_start (last); !tsi_one_before_end_p (i); tsi_next (&i))
7102             emit_side_effect_warnings (tsi_stmt (i));
7103         }
7104       else
7105         i = tsi_last (last);
7106       last_p = tsi_stmt_ptr (i);
7107       last = *last_p;
7108     }
7109
7110   /* If the end of the list is exception related, then the list was split
7111      by a call to push_cleanup.  Continue searching.  */
7112   if (TREE_CODE (last) == TRY_FINALLY_EXPR
7113       || TREE_CODE (last) == TRY_CATCH_EXPR)
7114     {
7115       last_p = &TREE_OPERAND (last, 0);
7116       last = *last_p;
7117       goto continue_searching;
7118     }
7119
7120   /* In the case that the BIND_EXPR is not necessary, return the
7121      expression out from inside it.  */
7122   if (last == error_mark_node
7123       || (last == BIND_EXPR_BODY (body)
7124           && BIND_EXPR_VARS (body) == NULL))
7125     return last;
7126
7127   /* Extract the type of said expression.  */
7128   type = TREE_TYPE (last);
7129
7130   /* If we're not returning a value at all, then the BIND_EXPR that
7131      we already have is a fine expression to return.  */
7132   if (!type || VOID_TYPE_P (type))
7133     return body;
7134
7135   /* Now that we've located the expression containing the value, it seems
7136      silly to make voidify_wrapper_expr repeat the process.  Create a
7137      temporary of the appropriate type and stick it in a TARGET_EXPR.  */
7138   tmp = create_tmp_var_raw (type, NULL);
7139
7140   /* Unwrap a no-op NOP_EXPR as added by c_finish_expr_stmt.  This avoids
7141      tree_expr_nonnegative_p giving up immediately.  */
7142   val = last;
7143   if (TREE_CODE (val) == NOP_EXPR
7144       && TREE_TYPE (val) == TREE_TYPE (TREE_OPERAND (val, 0)))
7145     val = TREE_OPERAND (val, 0);
7146
7147   *last_p = build2 (MODIFY_EXPR, void_type_node, tmp, val);
7148   SET_EXPR_LOCUS (*last_p, EXPR_LOCUS (last));
7149
7150   return build4 (TARGET_EXPR, type, tmp, body, NULL_TREE, NULL_TREE);
7151 }
7152 \f
7153 /* Begin and end compound statements.  This is as simple as pushing
7154    and popping new statement lists from the tree.  */
7155
7156 tree
7157 c_begin_compound_stmt (bool do_scope)
7158 {
7159   tree stmt = push_stmt_list ();
7160   if (do_scope)
7161     push_scope ();
7162   return stmt;
7163 }
7164
7165 tree
7166 c_end_compound_stmt (tree stmt, bool do_scope)
7167 {
7168   tree block = NULL;
7169
7170   if (do_scope)
7171     {
7172       if (c_dialect_objc ())
7173         objc_clear_super_receiver ();
7174       block = pop_scope ();
7175     }
7176
7177   stmt = pop_stmt_list (stmt);
7178   stmt = c_build_bind_expr (block, stmt);
7179
7180   /* If this compound statement is nested immediately inside a statement
7181      expression, then force a BIND_EXPR to be created.  Otherwise we'll
7182      do the wrong thing for ({ { 1; } }) or ({ 1; { } }).  In particular,
7183      STATEMENT_LISTs merge, and thus we can lose track of what statement
7184      was really last.  */
7185   if (cur_stmt_list
7186       && STATEMENT_LIST_STMT_EXPR (cur_stmt_list)
7187       && TREE_CODE (stmt) != BIND_EXPR)
7188     {
7189       stmt = build3 (BIND_EXPR, void_type_node, NULL, stmt, NULL);
7190       TREE_SIDE_EFFECTS (stmt) = 1;
7191     }
7192
7193   return stmt;
7194 }
7195
7196 /* Queue a cleanup.  CLEANUP is an expression/statement to be executed
7197    when the current scope is exited.  EH_ONLY is true when this is not
7198    meant to apply to normal control flow transfer.  */
7199
7200 void
7201 push_cleanup (tree ARG_UNUSED (decl), tree cleanup, bool eh_only)
7202 {
7203   enum tree_code code;
7204   tree stmt, list;
7205   bool stmt_expr;
7206
7207   code = eh_only ? TRY_CATCH_EXPR : TRY_FINALLY_EXPR;
7208   stmt = build_stmt (code, NULL, cleanup);
7209   add_stmt (stmt);
7210   stmt_expr = STATEMENT_LIST_STMT_EXPR (cur_stmt_list);
7211   list = push_stmt_list ();
7212   TREE_OPERAND (stmt, 0) = list;
7213   STATEMENT_LIST_STMT_EXPR (list) = stmt_expr;
7214 }
7215 \f
7216 /* Build a binary-operation expression without default conversions.
7217    CODE is the kind of expression to build.
7218    This function differs from `build' in several ways:
7219    the data type of the result is computed and recorded in it,
7220    warnings are generated if arg data types are invalid,
7221    special handling for addition and subtraction of pointers is known,
7222    and some optimization is done (operations on narrow ints
7223    are done in the narrower type when that gives the same result).
7224    Constant folding is also done before the result is returned.
7225
7226    Note that the operands will never have enumeral types, or function
7227    or array types, because either they will have the default conversions
7228    performed or they have both just been converted to some other type in which
7229    the arithmetic is to be done.  */
7230
7231 tree
7232 build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
7233                  int convert_p)
7234 {
7235   tree type0, type1;
7236   enum tree_code code0, code1;
7237   tree op0, op1;
7238
7239   /* Expression code to give to the expression when it is built.
7240      Normally this is CODE, which is what the caller asked for,
7241      but in some special cases we change it.  */
7242   enum tree_code resultcode = code;
7243
7244   /* Data type in which the computation is to be performed.
7245      In the simplest cases this is the common type of the arguments.  */
7246   tree result_type = NULL;
7247
7248   /* Nonzero means operands have already been type-converted
7249      in whatever way is necessary.
7250      Zero means they need to be converted to RESULT_TYPE.  */
7251   int converted = 0;
7252
7253   /* Nonzero means create the expression with this type, rather than
7254      RESULT_TYPE.  */
7255   tree build_type = 0;
7256
7257   /* Nonzero means after finally constructing the expression
7258      convert it to this type.  */
7259   tree final_type = 0;
7260
7261   /* Nonzero if this is an operation like MIN or MAX which can
7262      safely be computed in short if both args are promoted shorts.
7263      Also implies COMMON.
7264      -1 indicates a bitwise operation; this makes a difference
7265      in the exact conditions for when it is safe to do the operation
7266      in a narrower mode.  */
7267   int shorten = 0;
7268
7269   /* Nonzero if this is a comparison operation;
7270      if both args are promoted shorts, compare the original shorts.
7271      Also implies COMMON.  */
7272   int short_compare = 0;
7273
7274   /* Nonzero if this is a right-shift operation, which can be computed on the
7275      original short and then promoted if the operand is a promoted short.  */
7276   int short_shift = 0;
7277
7278   /* Nonzero means set RESULT_TYPE to the common type of the args.  */
7279   int common = 0;
7280
7281   if (convert_p)
7282     {
7283       op0 = default_conversion (orig_op0);
7284       op1 = default_conversion (orig_op1);
7285     }
7286   else
7287     {
7288       op0 = orig_op0;
7289       op1 = orig_op1;
7290     }
7291
7292   type0 = TREE_TYPE (op0);
7293   type1 = TREE_TYPE (op1);
7294
7295   /* The expression codes of the data types of the arguments tell us
7296      whether the arguments are integers, floating, pointers, etc.  */
7297   code0 = TREE_CODE (type0);
7298   code1 = TREE_CODE (type1);
7299
7300   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
7301   STRIP_TYPE_NOPS (op0);
7302   STRIP_TYPE_NOPS (op1);
7303
7304   /* If an error was already reported for one of the arguments,
7305      avoid reporting another error.  */
7306
7307   if (code0 == ERROR_MARK || code1 == ERROR_MARK)
7308     return error_mark_node;
7309
7310   switch (code)
7311     {
7312     case PLUS_EXPR:
7313       /* Handle the pointer + int case.  */
7314       if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7315         return pointer_int_sum (PLUS_EXPR, op0, op1);
7316       else if (code1 == POINTER_TYPE && code0 == INTEGER_TYPE)
7317         return pointer_int_sum (PLUS_EXPR, op1, op0);
7318       else
7319         common = 1;
7320       break;
7321
7322     case MINUS_EXPR:
7323       /* Subtraction of two similar pointers.
7324          We must subtract them as integers, then divide by object size.  */
7325       if (code0 == POINTER_TYPE && code1 == POINTER_TYPE
7326           && comp_target_types (type0, type1, 1))
7327         return pointer_diff (op0, op1);
7328       /* Handle pointer minus int.  Just like pointer plus int.  */
7329       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7330         return pointer_int_sum (MINUS_EXPR, op0, op1);
7331       else
7332         common = 1;
7333       break;
7334
7335     case MULT_EXPR:
7336       common = 1;
7337       break;
7338
7339     case TRUNC_DIV_EXPR:
7340     case CEIL_DIV_EXPR:
7341     case FLOOR_DIV_EXPR:
7342     case ROUND_DIV_EXPR:
7343     case EXACT_DIV_EXPR:
7344       /* Floating point division by zero is a legitimate way to obtain
7345          infinities and NaNs.  */
7346       if (warn_div_by_zero && skip_evaluation == 0 && integer_zerop (op1))
7347         warning ("division by zero");
7348
7349       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
7350            || code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
7351           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
7352               || code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE))
7353         {
7354           if (code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
7355             code0 = TREE_CODE (TREE_TYPE (TREE_TYPE (op0)));
7356           if (code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE)
7357             code1 = TREE_CODE (TREE_TYPE (TREE_TYPE (op1)));
7358
7359           if (!(code0 == INTEGER_TYPE && code1 == INTEGER_TYPE))
7360             resultcode = RDIV_EXPR;
7361           else
7362             /* Although it would be tempting to shorten always here, that
7363                loses on some targets, since the modulo instruction is
7364                undefined if the quotient can't be represented in the
7365                computation mode.  We shorten only if unsigned or if
7366                dividing by something we know != -1.  */
7367             shorten = (TYPE_UNSIGNED (TREE_TYPE (orig_op0))
7368                        || (TREE_CODE (op1) == INTEGER_CST
7369                            && !integer_all_onesp (op1)));
7370           common = 1;
7371         }
7372       break;
7373
7374     case BIT_AND_EXPR:
7375     case BIT_IOR_EXPR:
7376     case BIT_XOR_EXPR:
7377       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7378         shorten = -1;
7379       else if (code0 == VECTOR_TYPE && code1 == VECTOR_TYPE)
7380         common = 1;
7381       break;
7382
7383     case TRUNC_MOD_EXPR:
7384     case FLOOR_MOD_EXPR:
7385       if (warn_div_by_zero && skip_evaluation == 0 && integer_zerop (op1))
7386         warning ("division by zero");
7387
7388       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7389         {
7390           /* Although it would be tempting to shorten always here, that loses
7391              on some targets, since the modulo instruction is undefined if the
7392              quotient can't be represented in the computation mode.  We shorten
7393              only if unsigned or if dividing by something we know != -1.  */
7394           shorten = (TYPE_UNSIGNED (TREE_TYPE (orig_op0))
7395                      || (TREE_CODE (op1) == INTEGER_CST
7396                          && !integer_all_onesp (op1)));
7397           common = 1;
7398         }
7399       break;
7400
7401     case TRUTH_ANDIF_EXPR:
7402     case TRUTH_ORIF_EXPR:
7403     case TRUTH_AND_EXPR:
7404     case TRUTH_OR_EXPR:
7405     case TRUTH_XOR_EXPR:
7406       if ((code0 == INTEGER_TYPE || code0 == POINTER_TYPE
7407            || code0 == REAL_TYPE || code0 == COMPLEX_TYPE)
7408           && (code1 == INTEGER_TYPE || code1 == POINTER_TYPE
7409               || code1 == REAL_TYPE || code1 == COMPLEX_TYPE))
7410         {
7411           /* Result of these operations is always an int,
7412              but that does not mean the operands should be
7413              converted to ints!  */
7414           result_type = integer_type_node;
7415           op0 = c_common_truthvalue_conversion (op0);
7416           op1 = c_common_truthvalue_conversion (op1);
7417           converted = 1;
7418         }
7419       break;
7420
7421       /* Shift operations: result has same type as first operand;
7422          always convert second operand to int.
7423          Also set SHORT_SHIFT if shifting rightward.  */
7424
7425     case RSHIFT_EXPR:
7426       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7427         {
7428           if (TREE_CODE (op1) == INTEGER_CST && skip_evaluation == 0)
7429             {
7430               if (tree_int_cst_sgn (op1) < 0)
7431                 warning ("right shift count is negative");
7432               else
7433                 {
7434                   if (!integer_zerop (op1))
7435                     short_shift = 1;
7436
7437                   if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
7438                     warning ("right shift count >= width of type");
7439                 }
7440             }
7441
7442           /* Use the type of the value to be shifted.  */
7443           result_type = type0;
7444           /* Convert the shift-count to an integer, regardless of size
7445              of value being shifted.  */
7446           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
7447             op1 = convert (integer_type_node, op1);
7448           /* Avoid converting op1 to result_type later.  */
7449           converted = 1;
7450         }
7451       break;
7452
7453     case LSHIFT_EXPR:
7454       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7455         {
7456           if (TREE_CODE (op1) == INTEGER_CST && skip_evaluation == 0)
7457             {
7458               if (tree_int_cst_sgn (op1) < 0)
7459                 warning ("left shift count is negative");
7460
7461               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
7462                 warning ("left shift count >= width of type");
7463             }
7464
7465           /* Use the type of the value to be shifted.  */
7466           result_type = type0;
7467           /* Convert the shift-count to an integer, regardless of size
7468              of value being shifted.  */
7469           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
7470             op1 = convert (integer_type_node, op1);
7471           /* Avoid converting op1 to result_type later.  */
7472           converted = 1;
7473         }
7474       break;
7475
7476     case EQ_EXPR:
7477     case NE_EXPR:
7478       if (warn_float_equal && (code0 == REAL_TYPE || code1 == REAL_TYPE))
7479         warning ("comparing floating point with == or != is unsafe");
7480       /* Result of comparison is always int,
7481          but don't convert the args to int!  */
7482       build_type = integer_type_node;
7483       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
7484            || code0 == COMPLEX_TYPE)
7485           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
7486               || code1 == COMPLEX_TYPE))
7487         short_compare = 1;
7488       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
7489         {
7490           tree tt0 = TREE_TYPE (type0);
7491           tree tt1 = TREE_TYPE (type1);
7492           /* Anything compares with void *.  void * compares with anything.
7493              Otherwise, the targets must be compatible
7494              and both must be object or both incomplete.  */
7495           if (comp_target_types (type0, type1, 1))
7496             result_type = common_pointer_type (type0, type1);
7497           else if (VOID_TYPE_P (tt0))
7498             {
7499               /* op0 != orig_op0 detects the case of something
7500                  whose value is 0 but which isn't a valid null ptr const.  */
7501               if (pedantic && (!integer_zerop (op0) || op0 != orig_op0)
7502                   && TREE_CODE (tt1) == FUNCTION_TYPE)
7503                 pedwarn ("ISO C forbids comparison of %<void *%>"
7504                          " with function pointer");
7505             }
7506           else if (VOID_TYPE_P (tt1))
7507             {
7508               if (pedantic && (!integer_zerop (op1) || op1 != orig_op1)
7509                   && TREE_CODE (tt0) == FUNCTION_TYPE)
7510                 pedwarn ("ISO C forbids comparison of %<void *%>"
7511                          " with function pointer");
7512             }
7513           else
7514             pedwarn ("comparison of distinct pointer types lacks a cast");
7515
7516           if (result_type == NULL_TREE)
7517             result_type = ptr_type_node;
7518         }
7519       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
7520                && integer_zerop (op1))
7521         result_type = type0;
7522       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
7523                && integer_zerop (op0))
7524         result_type = type1;
7525       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7526         {
7527           result_type = type0;
7528           pedwarn ("comparison between pointer and integer");
7529         }
7530       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
7531         {
7532           result_type = type1;
7533           pedwarn ("comparison between pointer and integer");
7534         }
7535       break;
7536
7537     case LE_EXPR:
7538     case GE_EXPR:
7539     case LT_EXPR:
7540     case GT_EXPR:
7541       build_type = integer_type_node;
7542       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
7543           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
7544         short_compare = 1;
7545       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
7546         {
7547           if (comp_target_types (type0, type1, 1))
7548             {
7549               result_type = common_pointer_type (type0, type1);
7550               if (!COMPLETE_TYPE_P (TREE_TYPE (type0))
7551                   != !COMPLETE_TYPE_P (TREE_TYPE (type1)))
7552                 pedwarn ("comparison of complete and incomplete pointers");
7553               else if (pedantic
7554                        && TREE_CODE (TREE_TYPE (type0)) == FUNCTION_TYPE)
7555                 pedwarn ("ISO C forbids ordered comparisons of pointers to functions");
7556             }
7557           else
7558             {
7559               result_type = ptr_type_node;
7560               pedwarn ("comparison of distinct pointer types lacks a cast");
7561             }
7562         }
7563       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
7564                && integer_zerop (op1))
7565         {
7566           result_type = type0;
7567           if (pedantic || extra_warnings)
7568             pedwarn ("ordered comparison of pointer with integer zero");
7569         }
7570       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
7571                && integer_zerop (op0))
7572         {
7573           result_type = type1;
7574           if (pedantic)
7575             pedwarn ("ordered comparison of pointer with integer zero");
7576         }
7577       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7578         {
7579           result_type = type0;
7580           pedwarn ("comparison between pointer and integer");
7581         }
7582       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
7583         {
7584           result_type = type1;
7585           pedwarn ("comparison between pointer and integer");
7586         }
7587       break;
7588
7589     default:
7590       gcc_unreachable ();
7591     }
7592
7593   if (code0 == ERROR_MARK || code1 == ERROR_MARK)
7594     return error_mark_node;
7595
7596   if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE || code0 == COMPLEX_TYPE
7597        || code0 == VECTOR_TYPE)
7598       &&
7599       (code1 == INTEGER_TYPE || code1 == REAL_TYPE || code1 == COMPLEX_TYPE
7600        || code1 == VECTOR_TYPE))
7601     {
7602       int none_complex = (code0 != COMPLEX_TYPE && code1 != COMPLEX_TYPE);
7603
7604       if (shorten || common || short_compare)
7605         result_type = c_common_type (type0, type1);
7606
7607       /* For certain operations (which identify themselves by shorten != 0)
7608          if both args were extended from the same smaller type,
7609          do the arithmetic in that type and then extend.
7610
7611          shorten !=0 and !=1 indicates a bitwise operation.
7612          For them, this optimization is safe only if
7613          both args are zero-extended or both are sign-extended.
7614          Otherwise, we might change the result.
7615          Eg, (short)-1 | (unsigned short)-1 is (int)-1
7616          but calculated in (unsigned short) it would be (unsigned short)-1.  */
7617
7618       if (shorten && none_complex)
7619         {
7620           int unsigned0, unsigned1;
7621           tree arg0 = get_narrower (op0, &unsigned0);
7622           tree arg1 = get_narrower (op1, &unsigned1);
7623           /* UNS is 1 if the operation to be done is an unsigned one.  */
7624           int uns = TYPE_UNSIGNED (result_type);
7625           tree type;
7626
7627           final_type = result_type;
7628
7629           /* Handle the case that OP0 (or OP1) does not *contain* a conversion
7630              but it *requires* conversion to FINAL_TYPE.  */
7631
7632           if ((TYPE_PRECISION (TREE_TYPE (op0))
7633                == TYPE_PRECISION (TREE_TYPE (arg0)))
7634               && TREE_TYPE (op0) != final_type)
7635             unsigned0 = TYPE_UNSIGNED (TREE_TYPE (op0));
7636           if ((TYPE_PRECISION (TREE_TYPE (op1))
7637                == TYPE_PRECISION (TREE_TYPE (arg1)))
7638               && TREE_TYPE (op1) != final_type)
7639             unsigned1 = TYPE_UNSIGNED (TREE_TYPE (op1));
7640
7641           /* Now UNSIGNED0 is 1 if ARG0 zero-extends to FINAL_TYPE.  */
7642
7643           /* For bitwise operations, signedness of nominal type
7644              does not matter.  Consider only how operands were extended.  */
7645           if (shorten == -1)
7646             uns = unsigned0;
7647
7648           /* Note that in all three cases below we refrain from optimizing
7649              an unsigned operation on sign-extended args.
7650              That would not be valid.  */
7651
7652           /* Both args variable: if both extended in same way
7653              from same width, do it in that width.
7654              Do it unsigned if args were zero-extended.  */
7655           if ((TYPE_PRECISION (TREE_TYPE (arg0))
7656                < TYPE_PRECISION (result_type))
7657               && (TYPE_PRECISION (TREE_TYPE (arg1))
7658                   == TYPE_PRECISION (TREE_TYPE (arg0)))
7659               && unsigned0 == unsigned1
7660               && (unsigned0 || !uns))
7661             result_type
7662               = c_common_signed_or_unsigned_type
7663               (unsigned0, c_common_type (TREE_TYPE (arg0), TREE_TYPE (arg1)));
7664           else if (TREE_CODE (arg0) == INTEGER_CST
7665                    && (unsigned1 || !uns)
7666                    && (TYPE_PRECISION (TREE_TYPE (arg1))
7667                        < TYPE_PRECISION (result_type))
7668                    && (type
7669                        = c_common_signed_or_unsigned_type (unsigned1,
7670                                                            TREE_TYPE (arg1)),
7671                        int_fits_type_p (arg0, type)))
7672             result_type = type;
7673           else if (TREE_CODE (arg1) == INTEGER_CST
7674                    && (unsigned0 || !uns)
7675                    && (TYPE_PRECISION (TREE_TYPE (arg0))
7676                        < TYPE_PRECISION (result_type))
7677                    && (type
7678                        = c_common_signed_or_unsigned_type (unsigned0,
7679                                                            TREE_TYPE (arg0)),
7680                        int_fits_type_p (arg1, type)))
7681             result_type = type;
7682         }
7683
7684       /* Shifts can be shortened if shifting right.  */
7685
7686       if (short_shift)
7687         {
7688           int unsigned_arg;
7689           tree arg0 = get_narrower (op0, &unsigned_arg);
7690
7691           final_type = result_type;
7692
7693           if (arg0 == op0 && final_type == TREE_TYPE (op0))
7694             unsigned_arg = TYPE_UNSIGNED (TREE_TYPE (op0));
7695
7696           if (TYPE_PRECISION (TREE_TYPE (arg0)) < TYPE_PRECISION (result_type)
7697               /* We can shorten only if the shift count is less than the
7698                  number of bits in the smaller type size.  */
7699               && compare_tree_int (op1, TYPE_PRECISION (TREE_TYPE (arg0))) < 0
7700               /* We cannot drop an unsigned shift after sign-extension.  */
7701               && (!TYPE_UNSIGNED (final_type) || unsigned_arg))
7702             {
7703               /* Do an unsigned shift if the operand was zero-extended.  */
7704               result_type
7705                 = c_common_signed_or_unsigned_type (unsigned_arg,
7706                                                     TREE_TYPE (arg0));
7707               /* Convert value-to-be-shifted to that type.  */
7708               if (TREE_TYPE (op0) != result_type)
7709                 op0 = convert (result_type, op0);
7710               converted = 1;
7711             }
7712         }
7713
7714       /* Comparison operations are shortened too but differently.
7715          They identify themselves by setting short_compare = 1.  */
7716
7717       if (short_compare)
7718         {
7719           /* Don't write &op0, etc., because that would prevent op0
7720              from being kept in a register.
7721              Instead, make copies of the our local variables and
7722              pass the copies by reference, then copy them back afterward.  */
7723           tree xop0 = op0, xop1 = op1, xresult_type = result_type;
7724           enum tree_code xresultcode = resultcode;
7725           tree val
7726             = shorten_compare (&xop0, &xop1, &xresult_type, &xresultcode);
7727
7728           if (val != 0)
7729             return val;
7730
7731           op0 = xop0, op1 = xop1;
7732           converted = 1;
7733           resultcode = xresultcode;
7734
7735           if (warn_sign_compare && skip_evaluation == 0)
7736             {
7737               int op0_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op0));
7738               int op1_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op1));
7739               int unsignedp0, unsignedp1;
7740               tree primop0 = get_narrower (op0, &unsignedp0);
7741               tree primop1 = get_narrower (op1, &unsignedp1);
7742
7743               xop0 = orig_op0;
7744               xop1 = orig_op1;
7745               STRIP_TYPE_NOPS (xop0);
7746               STRIP_TYPE_NOPS (xop1);
7747
7748               /* Give warnings for comparisons between signed and unsigned
7749                  quantities that may fail.
7750
7751                  Do the checking based on the original operand trees, so that
7752                  casts will be considered, but default promotions won't be.
7753
7754                  Do not warn if the comparison is being done in a signed type,
7755                  since the signed type will only be chosen if it can represent
7756                  all the values of the unsigned type.  */
7757               if (!TYPE_UNSIGNED (result_type))
7758                 /* OK */;
7759               /* Do not warn if both operands are the same signedness.  */
7760               else if (op0_signed == op1_signed)
7761                 /* OK */;
7762               else
7763                 {
7764                   tree sop, uop;
7765
7766                   if (op0_signed)
7767                     sop = xop0, uop = xop1;
7768                   else
7769                     sop = xop1, uop = xop0;
7770
7771                   /* Do not warn if the signed quantity is an
7772                      unsuffixed integer literal (or some static
7773                      constant expression involving such literals or a
7774                      conditional expression involving such literals)
7775                      and it is non-negative.  */
7776                   if (tree_expr_nonnegative_p (sop))
7777                     /* OK */;
7778                   /* Do not warn if the comparison is an equality operation,
7779                      the unsigned quantity is an integral constant, and it
7780                      would fit in the result if the result were signed.  */
7781                   else if (TREE_CODE (uop) == INTEGER_CST
7782                            && (resultcode == EQ_EXPR || resultcode == NE_EXPR)
7783                            && int_fits_type_p
7784                            (uop, c_common_signed_type (result_type)))
7785                     /* OK */;
7786                   /* Do not warn if the unsigned quantity is an enumeration
7787                      constant and its maximum value would fit in the result
7788                      if the result were signed.  */
7789                   else if (TREE_CODE (uop) == INTEGER_CST
7790                            && TREE_CODE (TREE_TYPE (uop)) == ENUMERAL_TYPE
7791                            && int_fits_type_p
7792                            (TYPE_MAX_VALUE (TREE_TYPE (uop)),
7793                             c_common_signed_type (result_type)))
7794                     /* OK */;
7795                   else
7796                     warning ("comparison between signed and unsigned");
7797                 }
7798
7799               /* Warn if two unsigned values are being compared in a size
7800                  larger than their original size, and one (and only one) is the
7801                  result of a `~' operator.  This comparison will always fail.
7802
7803                  Also warn if one operand is a constant, and the constant
7804                  does not have all bits set that are set in the ~ operand
7805                  when it is extended.  */
7806
7807               if ((TREE_CODE (primop0) == BIT_NOT_EXPR)
7808                   != (TREE_CODE (primop1) == BIT_NOT_EXPR))
7809                 {
7810                   if (TREE_CODE (primop0) == BIT_NOT_EXPR)
7811                     primop0 = get_narrower (TREE_OPERAND (primop0, 0),
7812                                             &unsignedp0);
7813                   else
7814                     primop1 = get_narrower (TREE_OPERAND (primop1, 0),
7815                                             &unsignedp1);
7816
7817                   if (host_integerp (primop0, 0) || host_integerp (primop1, 0))
7818                     {
7819                       tree primop;
7820                       HOST_WIDE_INT constant, mask;
7821                       int unsignedp, bits;
7822
7823                       if (host_integerp (primop0, 0))
7824                         {
7825                           primop = primop1;
7826                           unsignedp = unsignedp1;
7827                           constant = tree_low_cst (primop0, 0);
7828                         }
7829                       else
7830                         {
7831                           primop = primop0;
7832                           unsignedp = unsignedp0;
7833                           constant = tree_low_cst (primop1, 0);
7834                         }
7835
7836                       bits = TYPE_PRECISION (TREE_TYPE (primop));
7837                       if (bits < TYPE_PRECISION (result_type)
7838                           && bits < HOST_BITS_PER_WIDE_INT && unsignedp)
7839                         {
7840                           mask = (~(HOST_WIDE_INT) 0) << bits;
7841                           if ((mask & constant) != mask)
7842                             warning ("comparison of promoted ~unsigned with constant");
7843                         }
7844                     }
7845                   else if (unsignedp0 && unsignedp1
7846                            && (TYPE_PRECISION (TREE_TYPE (primop0))
7847                                < TYPE_PRECISION (result_type))
7848                            && (TYPE_PRECISION (TREE_TYPE (primop1))
7849                                < TYPE_PRECISION (result_type)))
7850                     warning ("comparison of promoted ~unsigned with unsigned");
7851                 }
7852             }
7853         }
7854     }
7855
7856   /* At this point, RESULT_TYPE must be nonzero to avoid an error message.
7857      If CONVERTED is zero, both args will be converted to type RESULT_TYPE.
7858      Then the expression will be built.
7859      It will be given type FINAL_TYPE if that is nonzero;
7860      otherwise, it will be given type RESULT_TYPE.  */
7861
7862   if (!result_type)
7863     {
7864       binary_op_error (code);
7865       return error_mark_node;
7866     }
7867
7868   if (!converted)
7869     {
7870       if (TREE_TYPE (op0) != result_type)
7871         op0 = convert (result_type, op0);
7872       if (TREE_TYPE (op1) != result_type)
7873         op1 = convert (result_type, op1);
7874
7875       /* This can happen if one operand has a vector type, and the other
7876          has a different type.  */
7877       if (TREE_CODE (op0) == ERROR_MARK || TREE_CODE (op1) == ERROR_MARK)
7878         return error_mark_node;
7879     }
7880
7881   if (build_type == NULL_TREE)
7882     build_type = result_type;
7883
7884   {
7885     tree result = build2 (resultcode, build_type, op0, op1);
7886
7887     /* Treat expressions in initializers specially as they can't trap.  */
7888     result = require_constant_value ? fold_initializer (result)
7889                                     : fold (result);
7890
7891     if (final_type != 0)
7892       result = convert (final_type, result);
7893     return result;
7894   }
7895 }
7896
7897
7898 /* Convert EXPR to be a truth-value, validating its type for this
7899    purpose.  Passes EXPR to default_function_array_conversion.  */
7900
7901 tree
7902 c_objc_common_truthvalue_conversion (tree expr)
7903 {
7904   expr = default_function_array_conversion (expr);
7905   switch (TREE_CODE (TREE_TYPE (expr)))
7906     {
7907     case ARRAY_TYPE:
7908       error ("used array that cannot be converted to pointer where scalar is required");
7909       return error_mark_node;
7910
7911     case RECORD_TYPE:
7912       error ("used struct type value where scalar is required");
7913       return error_mark_node;
7914
7915     case UNION_TYPE:
7916       error ("used union type value where scalar is required");
7917       return error_mark_node;
7918
7919     default:
7920       break;
7921     }
7922
7923   /* ??? Should we also give an error for void and vectors rather than
7924      leaving those to give errors later?  */
7925   return c_common_truthvalue_conversion (expr);
7926 }