gcc/c-typeck.c

   1 /* Build expressions with type checking for C compiler.
   2    Copyright (C) 1987, 1988, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  20 02110-1301, USA.  */
  21
  22
  23 /* This file is part of the C front end.
  24    It contains routines to build C expressions given their operands,
  25    including computing the types of the result, C-specific error checks,
  26    and some optimization.  */
  27
  28 #include "config.h"
  29 #include "system.h"
  30 #include "coretypes.h"
  31 #include "tm.h"
  32 #include "rtl.h"
  33 #include "tree.h"
  34 #include "langhooks.h"
  35 #include "c-tree.h"
  36 #include "tm_p.h"
  37 #include "flags.h"
  38 #include "output.h"
  39 #include "expr.h"
  40 #include "toplev.h"
  41 #include "intl.h"
  42 #include "ggc.h"
  43 #include "target.h"
  44 #include "tree-iterator.h"
  45 #include "tree-gimple.h"
  46 #include "tree-flow.h"
  47
  48 /* Possible cases of implicit bad conversions.  Used to select
  49    diagnostic messages in convert_for_assignment.  */
  50 enum impl_conv {
  51   ic_argpass,
  52   ic_argpass_nonproto,
  53   ic_assign,
  54   ic_init,
  55   ic_return
  56 };
  57
  58 /* The level of nesting inside "__alignof__".  */
  59 int in_alignof;
  60
  61 /* The level of nesting inside "sizeof".  */
  62 int in_sizeof;
  63
  64 /* The level of nesting inside "typeof".  */
  65 int in_typeof;
  66
  67 struct c_label_context_se *label_context_stack_se;
  68 struct c_label_context_vm *label_context_stack_vm;
  69
  70 /* Nonzero if we've already printed a "missing braces around initializer"
  71    message within this initializer.  */
  72 static int missing_braces_mentioned;
  73
  74 static int require_constant_value;
  75 static int require_constant_elements;
  76
  77 static tree qualify_type (tree, tree);
  78 static int tagged_types_tu_compatible_p (tree, tree);
  79 static int comp_target_types (tree, tree);
  80 static int function_types_compatible_p (tree, tree);
  81 static int type_lists_compatible_p (tree, tree);
  82 static tree decl_constant_value_for_broken_optimization (tree);
  83 static tree lookup_field (tree, tree);
  84 static tree convert_arguments (tree, tree, tree, tree);
  85 static tree pointer_diff (tree, tree);
  86 static tree convert_for_assignment (tree, tree, enum impl_conv, tree, tree,
  87                                     int);
  88 static tree valid_compound_expr_initializer (tree, tree);
  89 static void push_string (const char *);
  90 static void push_member_name (tree);
  91 static void push_array_bounds (int);
  92 static int spelling_length (void);
  93 static char *print_spelling (char *);
  94 static void warning_init (const char *);
  95 static tree digest_init (tree, tree, bool, int);
  96 static void output_init_element (tree, bool, tree, tree, int);
  97 static void output_pending_init_elements (int);
  98 static int set_designator (int);
  99 static void push_range_stack (tree);
 100 static void add_pending_init (tree, tree);
 101 static void set_nonincremental_init (void);
 102 static void set_nonincremental_init_from_string (tree);
 103 static tree find_init_member (tree);
 104 static void readonly_error (tree, enum lvalue_use);
 105 static int lvalue_or_else (tree, enum lvalue_use);
 106 static int lvalue_p (tree);
 107 static void record_maybe_used_decl (tree);
 108 \f
 109 /* Do `exp = require_complete_type (exp);' to make sure exp
 110    does not have an incomplete type.  (That includes void types.)  */
 111
 112 tree
 113 require_complete_type (tree value)
 114 {
 115   tree type = TREE_TYPE (value);
 116
 117   if (value == error_mark_node || type == error_mark_node)
 118     return error_mark_node;
 119
 120   /* First, detect a valid value with a complete type.  */
 121   if (COMPLETE_TYPE_P (type))
 122     return value;
 123
 124   c_incomplete_type_error (value, type);
 125   return error_mark_node;
 126 }
 127
 128 /* Print an error message for invalid use of an incomplete type.
 129    VALUE is the expression that was used (or 0 if that isn't known)
 130    and TYPE is the type that was invalid.  */
 131
 132 void
 133 c_incomplete_type_error (tree value, tree type)
 134 {
 135   const char *type_code_string;
 136
 137   /* Avoid duplicate error message.  */
 138   if (TREE_CODE (type) == ERROR_MARK)
 139     return;
 140
 141   if (value != 0 && (TREE_CODE (value) == VAR_DECL
 142                      || TREE_CODE (value) == PARM_DECL))
 143     error ("%qD has an incomplete type", value);
 144   else
 145     {
 146     retry:
 147       /* We must print an error message.  Be clever about what it says.  */
 148
 149       switch (TREE_CODE (type))
 150         {
 151         case RECORD_TYPE:
 152           type_code_string = "struct";
 153           break;
 154
 155         case UNION_TYPE:
 156           type_code_string = "union";
 157           break;
 158
 159         case ENUMERAL_TYPE:
 160           type_code_string = "enum";
 161           break;
 162
 163         case VOID_TYPE:
 164           error ("invalid use of void expression");
 165           return;
 166
 167         case ARRAY_TYPE:
 168           if (TYPE_DOMAIN (type))
 169             {
 170               if (TYPE_MAX_VALUE (TYPE_DOMAIN (type)) == NULL)
 171                 {
 172                   error ("invalid use of flexible array member");
 173                   return;
 174                 }
 175               type = TREE_TYPE (type);
 176               goto retry;
 177             }
 178           error ("invalid use of array with unspecified bounds");
 179           return;
 180
 181         default:
 182           gcc_unreachable ();
 183         }
 184
 185       if (TREE_CODE (TYPE_NAME (type)) == IDENTIFIER_NODE)
 186         error ("invalid use of undefined type %<%s %E%>",
 187                type_code_string, TYPE_NAME (type));
 188       else
 189         /* If this type has a typedef-name, the TYPE_NAME is a TYPE_DECL.  */
 190         error ("invalid use of incomplete typedef %qD", TYPE_NAME (type));
 191     }
 192 }
 193
 194 /* Given a type, apply default promotions wrt unnamed function
 195    arguments and return the new type.  */
 196
 197 tree
 198 c_type_promotes_to (tree type)
 199 {
 200   if (TYPE_MAIN_VARIANT (type) == float_type_node)
 201     return double_type_node;
 202
 203   if (c_promoting_integer_type_p (type))
 204     {
 205       /* Preserve unsignedness if not really getting any wider.  */
 206       if (TYPE_UNSIGNED (type)
 207           && (TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node)))
 208         return unsigned_type_node;
 209       return integer_type_node;
 210     }
 211
 212   return type;
 213 }
 214
 215 /* Return a variant of TYPE which has all the type qualifiers of LIKE
 216    as well as those of TYPE.  */
 217
 218 static tree
 219 qualify_type (tree type, tree like)
 220 {
 221   return c_build_qualified_type (type,
 222                                  TYPE_QUALS (type) | TYPE_QUALS (like));
 223 }
 224 \f
 225 /* Return the composite type of two compatible types.
 226
 227    We assume that comptypes has already been done and returned
 228    nonzero; if that isn't so, this may crash.  In particular, we
 229    assume that qualifiers match.  */
 230
 231 tree
 232 composite_type (tree t1, tree t2)
 233 {
 234   enum tree_code code1;
 235   enum tree_code code2;
 236   tree attributes;
 237
 238   /* Save time if the two types are the same.  */
 239
 240   if (t1 == t2) return t1;
 241
 242   /* If one type is nonsense, use the other.  */
 243   if (t1 == error_mark_node)
 244     return t2;
 245   if (t2 == error_mark_node)
 246     return t1;
 247
 248   code1 = TREE_CODE (t1);
 249   code2 = TREE_CODE (t2);
 250
 251   /* Merge the attributes.  */
 252   attributes = targetm.merge_type_attributes (t1, t2);
 253
 254   /* If one is an enumerated type and the other is the compatible
 255      integer type, the composite type might be either of the two
 256      (DR#013 question 3).  For consistency, use the enumerated type as
 257      the composite type.  */
 258
 259   if (code1 == ENUMERAL_TYPE && code2 == INTEGER_TYPE)
 260     return t1;
 261   if (code2 == ENUMERAL_TYPE && code1 == INTEGER_TYPE)
 262     return t2;
 263
 264   gcc_assert (code1 == code2);
 265
 266   switch (code1)
 267     {
 268     case POINTER_TYPE:
 269       /* For two pointers, do this recursively on the target type.  */
 270       {
 271         tree pointed_to_1 = TREE_TYPE (t1);
 272         tree pointed_to_2 = TREE_TYPE (t2);
 273         tree target = composite_type (pointed_to_1, pointed_to_2);
 274         t1 = build_pointer_type (target);
 275         t1 = build_type_attribute_variant (t1, attributes);
 276         return qualify_type (t1, t2);
 277       }
 278
 279     case ARRAY_TYPE:
 280       {
 281         tree elt = composite_type (TREE_TYPE (t1), TREE_TYPE (t2));
 282         int quals;
 283         tree unqual_elt;
 284         tree d1 = TYPE_DOMAIN (t1);
 285         tree d2 = TYPE_DOMAIN (t2);
 286         bool d1_variable, d2_variable;
 287         bool d1_zero, d2_zero;
 288
 289         /* We should not have any type quals on arrays at all.  */
 290         gcc_assert (!TYPE_QUALS (t1) && !TYPE_QUALS (t2));
 291
 292         d1_zero = d1 == 0 || !TYPE_MAX_VALUE (d1);
 293         d2_zero = d2 == 0 || !TYPE_MAX_VALUE (d2);
 294
 295         d1_variable = (!d1_zero
 296                        && (TREE_CODE (TYPE_MIN_VALUE (d1)) != INTEGER_CST
 297                            || TREE_CODE (TYPE_MAX_VALUE (d1)) != INTEGER_CST));
 298         d2_variable = (!d2_zero
 299                        && (TREE_CODE (TYPE_MIN_VALUE (d2)) != INTEGER_CST
 300                            || TREE_CODE (TYPE_MAX_VALUE (d2)) != INTEGER_CST));
 301
 302         /* Save space: see if the result is identical to one of the args.  */
 303         if (elt == TREE_TYPE (t1) && TYPE_DOMAIN (t1)
 304             && (d2_variable || d2_zero || !d1_variable))
 305           return build_type_attribute_variant (t1, attributes);
 306         if (elt == TREE_TYPE (t2) && TYPE_DOMAIN (t2)
 307             && (d1_variable || d1_zero || !d2_variable))
 308           return build_type_attribute_variant (t2, attributes);
 309
 310         if (elt == TREE_TYPE (t1) && !TYPE_DOMAIN (t2) && !TYPE_DOMAIN (t1))
 311           return build_type_attribute_variant (t1, attributes);
 312         if (elt == TREE_TYPE (t2) && !TYPE_DOMAIN (t2) && !TYPE_DOMAIN (t1))
 313           return build_type_attribute_variant (t2, attributes);
 314
 315         /* Merge the element types, and have a size if either arg has
 316            one.  We may have qualifiers on the element types.  To set
 317            up TYPE_MAIN_VARIANT correctly, we need to form the
 318            composite of the unqualified types and add the qualifiers
 319            back at the end.  */
 320         quals = TYPE_QUALS (strip_array_types (elt));
 321         unqual_elt = c_build_qualified_type (elt, TYPE_UNQUALIFIED);
 322         t1 = build_array_type (unqual_elt,
 323                                TYPE_DOMAIN ((TYPE_DOMAIN (t1)
 324                                              && (d2_variable
 325                                                  || d2_zero
 326                                                  || !d1_variable))
 327                                             ? t1
 328                                             : t2));
 329         t1 = c_build_qualified_type (t1, quals);
 330         return build_type_attribute_variant (t1, attributes);
 331       }
 332
 333     case FUNCTION_TYPE:
 334       /* Function types: prefer the one that specified arg types.
 335          If both do, merge the arg types.  Also merge the return types.  */
 336       {
 337         tree valtype = composite_type (TREE_TYPE (t1), TREE_TYPE (t2));
 338         tree p1 = TYPE_ARG_TYPES (t1);
 339         tree p2 = TYPE_ARG_TYPES (t2);
 340         int len;
 341         tree newargs, n;
 342         int i;
 343
 344         /* Save space: see if the result is identical to one of the args.  */
 345         if (valtype == TREE_TYPE (t1) && !TYPE_ARG_TYPES (t2))
 346           return build_type_attribute_variant (t1, attributes);
 347         if (valtype == TREE_TYPE (t2) && !TYPE_ARG_TYPES (t1))
 348           return build_type_attribute_variant (t2, attributes);
 349
 350         /* Simple way if one arg fails to specify argument types.  */
 351         if (TYPE_ARG_TYPES (t1) == 0)
 352          {
 353             t1 = build_function_type (valtype, TYPE_ARG_TYPES (t2));
 354             t1 = build_type_attribute_variant (t1, attributes);
 355             return qualify_type (t1, t2);
 356          }
 357         if (TYPE_ARG_TYPES (t2) == 0)
 358          {
 359            t1 = build_function_type (valtype, TYPE_ARG_TYPES (t1));
 360            t1 = build_type_attribute_variant (t1, attributes);
 361            return qualify_type (t1, t2);
 362          }
 363
 364         /* If both args specify argument types, we must merge the two
 365            lists, argument by argument.  */
 366         /* Tell global_bindings_p to return false so that variable_size
 367            doesn't die on VLAs in parameter types.  */
 368         c_override_global_bindings_to_false = true;
 369
 370         len = list_length (p1);
 371         newargs = 0;
 372
 373         for (i = 0; i < len; i++)
 374           newargs = tree_cons (NULL_TREE, NULL_TREE, newargs);
 375
 376         n = newargs;
 377
 378         for (; p1;
 379              p1 = TREE_CHAIN (p1), p2 = TREE_CHAIN (p2), n = TREE_CHAIN (n))
 380           {
 381             /* A null type means arg type is not specified.
 382                Take whatever the other function type has.  */
 383             if (TREE_VALUE (p1) == 0)
 384               {
 385                 TREE_VALUE (n) = TREE_VALUE (p2);
 386                 goto parm_done;
 387               }
 388             if (TREE_VALUE (p2) == 0)
 389               {
 390                 TREE_VALUE (n) = TREE_VALUE (p1);
 391                 goto parm_done;
 392               }
 393
 394             /* Given  wait (union {union wait *u; int *i} *)
 395                and  wait (union wait *),
 396                prefer  union wait *  as type of parm.  */
 397             if (TREE_CODE (TREE_VALUE (p1)) == UNION_TYPE
 398                 && TREE_VALUE (p1) != TREE_VALUE (p2))
 399               {
 400                 tree memb;
 401                 tree mv2 = TREE_VALUE (p2);
 402                 if (mv2 && mv2 != error_mark_node
 403                     && TREE_CODE (mv2) != ARRAY_TYPE)
 404                   mv2 = TYPE_MAIN_VARIANT (mv2);
 405                 for (memb = TYPE_FIELDS (TREE_VALUE (p1));
 406                      memb; memb = TREE_CHAIN (memb))
 407                   {
 408                     tree mv3 = TREE_TYPE (memb);
 409                     if (mv3 && mv3 != error_mark_node
 410                         && TREE_CODE (mv3) != ARRAY_TYPE)
 411                       mv3 = TYPE_MAIN_VARIANT (mv3);
 412                     if (comptypes (mv3, mv2))
 413                       {
 414                         TREE_VALUE (n) = composite_type (TREE_TYPE (memb),
 415                                                          TREE_VALUE (p2));
 416                         if (pedantic)
 417                           pedwarn ("function types not truly compatible in ISO C");
 418                         goto parm_done;
 419                       }
 420                   }
 421               }
 422             if (TREE_CODE (TREE_VALUE (p2)) == UNION_TYPE
 423                 && TREE_VALUE (p2) != TREE_VALUE (p1))
 424               {
 425                 tree memb;
 426                 tree mv1 = TREE_VALUE (p1);
 427                 if (mv1 && mv1 != error_mark_node
 428                     && TREE_CODE (mv1) != ARRAY_TYPE)
 429                   mv1 = TYPE_MAIN_VARIANT (mv1);
 430                 for (memb = TYPE_FIELDS (TREE_VALUE (p2));
 431                      memb; memb = TREE_CHAIN (memb))
 432                   {
 433                     tree mv3 = TREE_TYPE (memb);
 434                     if (mv3 && mv3 != error_mark_node
 435                         && TREE_CODE (mv3) != ARRAY_TYPE)
 436                       mv3 = TYPE_MAIN_VARIANT (mv3);
 437                     if (comptypes (mv3, mv1))
 438                       {
 439                         TREE_VALUE (n) = composite_type (TREE_TYPE (memb),
 440                                                          TREE_VALUE (p1));
 441                         if (pedantic)
 442                           pedwarn ("function types not truly compatible in ISO C");
 443                         goto parm_done;
 444                       }
 445                   }
 446               }
 447             TREE_VALUE (n) = composite_type (TREE_VALUE (p1), TREE_VALUE (p2));
 448           parm_done: ;
 449           }
 450
 451         c_override_global_bindings_to_false = false;
 452         t1 = build_function_type (valtype, newargs);
 453         t1 = qualify_type (t1, t2);
 454         /* ... falls through ...  */
 455       }
 456
 457     default:
 458       return build_type_attribute_variant (t1, attributes);
 459     }
 460
 461 }
 462
 463 /* Return the type of a conditional expression between pointers to
 464    possibly differently qualified versions of compatible types.
 465
 466    We assume that comp_target_types has already been done and returned
 467    nonzero; if that isn't so, this may crash.  */
 468
 469 static tree
 470 common_pointer_type (tree t1, tree t2)
 471 {
 472   tree attributes;
 473   tree pointed_to_1, mv1;
 474   tree pointed_to_2, mv2;
 475   tree target;
 476
 477   /* Save time if the two types are the same.  */
 478
 479   if (t1 == t2) return t1;
 480
 481   /* If one type is nonsense, use the other.  */
 482   if (t1 == error_mark_node)
 483     return t2;
 484   if (t2 == error_mark_node)
 485     return t1;
 486
 487   gcc_assert (TREE_CODE (t1) == POINTER_TYPE
 488               && TREE_CODE (t2) == POINTER_TYPE);
 489
 490   /* Merge the attributes.  */
 491   attributes = targetm.merge_type_attributes (t1, t2);
 492
 493   /* Find the composite type of the target types, and combine the
 494      qualifiers of the two types' targets.  Do not lose qualifiers on
 495      array element types by taking the TYPE_MAIN_VARIANT.  */
 496   mv1 = pointed_to_1 = TREE_TYPE (t1);
 497   mv2 = pointed_to_2 = TREE_TYPE (t2);
 498   if (TREE_CODE (mv1) != ARRAY_TYPE)
 499     mv1 = TYPE_MAIN_VARIANT (pointed_to_1);
 500   if (TREE_CODE (mv2) != ARRAY_TYPE)
 501     mv2 = TYPE_MAIN_VARIANT (pointed_to_2);
 502   target = composite_type (mv1, mv2);
 503   t1 = build_pointer_type (c_build_qualified_type
 504                            (target,
 505                             TYPE_QUALS (pointed_to_1) |
 506                             TYPE_QUALS (pointed_to_2)));
 507   return build_type_attribute_variant (t1, attributes);
 508 }
 509
 510 /* Return the common type for two arithmetic types under the usual
 511    arithmetic conversions.  The default conversions have already been
 512    applied, and enumerated types converted to their compatible integer
 513    types.  The resulting type is unqualified and has no attributes.
 514
 515    This is the type for the result of most arithmetic operations
 516    if the operands have the given two types.  */
 517
 518 static tree
 519 c_common_type (tree t1, tree t2)
 520 {
 521   enum tree_code code1;
 522   enum tree_code code2;
 523
 524   /* If one type is nonsense, use the other.  */
 525   if (t1 == error_mark_node)
 526     return t2;
 527   if (t2 == error_mark_node)
 528     return t1;
 529
 530   if (TYPE_QUALS (t1) != TYPE_UNQUALIFIED)
 531     t1 = TYPE_MAIN_VARIANT (t1);
 532
 533   if (TYPE_QUALS (t2) != TYPE_UNQUALIFIED)
 534     t2 = TYPE_MAIN_VARIANT (t2);
 535
 536   if (TYPE_ATTRIBUTES (t1) != NULL_TREE)
 537     t1 = build_type_attribute_variant (t1, NULL_TREE);
 538
 539   if (TYPE_ATTRIBUTES (t2) != NULL_TREE)
 540     t2 = build_type_attribute_variant (t2, NULL_TREE);
 541
 542   /* Save time if the two types are the same.  */
 543
 544   if (t1 == t2) return t1;
 545
 546   code1 = TREE_CODE (t1);
 547   code2 = TREE_CODE (t2);
 548
 549   gcc_assert (code1 == VECTOR_TYPE || code1 == COMPLEX_TYPE
 550               || code1 == REAL_TYPE || code1 == INTEGER_TYPE);
 551   gcc_assert (code2 == VECTOR_TYPE || code2 == COMPLEX_TYPE
 552               || code2 == REAL_TYPE || code2 == INTEGER_TYPE);
 553
 554   /* If one type is a vector type, return that type.  (How the usual
 555      arithmetic conversions apply to the vector types extension is not
 556      precisely specified.)  */
 557   if (code1 == VECTOR_TYPE)
 558     return t1;
 559
 560   if (code2 == VECTOR_TYPE)
 561     return t2;
 562
 563   /* If one type is complex, form the common type of the non-complex
 564      components, then make that complex.  Use T1 or T2 if it is the
 565      required type.  */
 566   if (code1 == COMPLEX_TYPE || code2 == COMPLEX_TYPE)
 567     {
 568       tree subtype1 = code1 == COMPLEX_TYPE ? TREE_TYPE (t1) : t1;
 569       tree subtype2 = code2 == COMPLEX_TYPE ? TREE_TYPE (t2) : t2;
 570       tree subtype = c_common_type (subtype1, subtype2);
 571
 572       if (code1 == COMPLEX_TYPE && TREE_TYPE (t1) == subtype)
 573         return t1;
 574       else if (code2 == COMPLEX_TYPE && TREE_TYPE (t2) == subtype)
 575         return t2;
 576       else
 577         return build_complex_type (subtype);
 578     }
 579
 580   /* If only one is real, use it as the result.  */
 581
 582   if (code1 == REAL_TYPE && code2 != REAL_TYPE)
 583     return t1;
 584
 585   if (code2 == REAL_TYPE && code1 != REAL_TYPE)
 586     return t2;
 587
 588   /* Both real or both integers; use the one with greater precision.  */
 589
 590   if (TYPE_PRECISION (t1) > TYPE_PRECISION (t2))
 591     return t1;
 592   else if (TYPE_PRECISION (t2) > TYPE_PRECISION (t1))
 593     return t2;
 594
 595   /* Same precision.  Prefer long longs to longs to ints when the
 596      same precision, following the C99 rules on integer type rank
 597      (which are equivalent to the C90 rules for C90 types).  */
 598
 599   if (TYPE_MAIN_VARIANT (t1) == long_long_unsigned_type_node
 600       || TYPE_MAIN_VARIANT (t2) == long_long_unsigned_type_node)
 601     return long_long_unsigned_type_node;
 602
 603   if (TYPE_MAIN_VARIANT (t1) == long_long_integer_type_node
 604       || TYPE_MAIN_VARIANT (t2) == long_long_integer_type_node)
 605     {
 606       if (TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 607         return long_long_unsigned_type_node;
 608       else
 609         return long_long_integer_type_node;
 610     }
 611
 612   if (TYPE_MAIN_VARIANT (t1) == long_unsigned_type_node
 613       || TYPE_MAIN_VARIANT (t2) == long_unsigned_type_node)
 614     return long_unsigned_type_node;
 615
 616   if (TYPE_MAIN_VARIANT (t1) == long_integer_type_node
 617       || TYPE_MAIN_VARIANT (t2) == long_integer_type_node)
 618     {
 619       /* But preserve unsignedness from the other type,
 620          since long cannot hold all the values of an unsigned int.  */
 621       if (TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
 622         return long_unsigned_type_node;
 623       else
 624         return long_integer_type_node;
 625     }
 626
 627   /* Likewise, prefer long double to double even if same size.  */
 628   if (TYPE_MAIN_VARIANT (t1) == long_double_type_node
 629       || TYPE_MAIN_VARIANT (t2) == long_double_type_node)
 630     return long_double_type_node;
 631
 632   /* Otherwise prefer the unsigned one.  */
 633
 634   if (TYPE_UNSIGNED (t1))
 635     return t1;
 636   else
 637     return t2;
 638 }
 639 \f
 640 /* Wrapper around c_common_type that is used by c-common.c and other
 641    front end optimizations that remove promotions.  ENUMERAL_TYPEs
 642    are allowed here and are converted to their compatible integer types.
 643    BOOLEAN_TYPEs are allowed here and return either boolean_type_node or
 644    preferably a non-Boolean type as the common type.  */
 645 tree
 646 common_type (tree t1, tree t2)
 647 {
 648   if (TREE_CODE (t1) == ENUMERAL_TYPE)
 649     t1 = c_common_type_for_size (TYPE_PRECISION (t1), 1);
 650   if (TREE_CODE (t2) == ENUMERAL_TYPE)
 651     t2 = c_common_type_for_size (TYPE_PRECISION (t2), 1);
 652
 653   /* If both types are BOOLEAN_TYPE, then return boolean_type_node.  */
 654   if (TREE_CODE (t1) == BOOLEAN_TYPE
 655       && TREE_CODE (t2) == BOOLEAN_TYPE)
 656     return boolean_type_node;
 657
 658   /* If either type is BOOLEAN_TYPE, then return the other.  */
 659   if (TREE_CODE (t1) == BOOLEAN_TYPE)
 660     return t2;
 661   if (TREE_CODE (t2) == BOOLEAN_TYPE)
 662     return t1;
 663
 664   return c_common_type (t1, t2);
 665 }
 666 \f
 667 /* Return 1 if TYPE1 and TYPE2 are compatible types for assignment
 668    or various other operations.  Return 2 if they are compatible
 669    but a warning may be needed if you use them together.  */
 670
 671 int
 672 comptypes (tree type1, tree type2)
 673 {
 674   tree t1 = type1;
 675   tree t2 = type2;
 676   int attrval, val;
 677
 678   /* Suppress errors caused by previously reported errors.  */
 679
 680   if (t1 == t2 || !t1 || !t2
 681       || TREE_CODE (t1) == ERROR_MARK || TREE_CODE (t2) == ERROR_MARK)
 682     return 1;
 683
 684   /* If either type is the internal version of sizetype, return the
 685      language version.  */
 686   if (TREE_CODE (t1) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t1)
 687       && TYPE_ORIG_SIZE_TYPE (t1))
 688     t1 = TYPE_ORIG_SIZE_TYPE (t1);
 689
 690   if (TREE_CODE (t2) == INTEGER_TYPE && TYPE_IS_SIZETYPE (t2)
 691       && TYPE_ORIG_SIZE_TYPE (t2))
 692     t2 = TYPE_ORIG_SIZE_TYPE (t2);
 693
 694
 695   /* Enumerated types are compatible with integer types, but this is
 696      not transitive: two enumerated types in the same translation unit
 697      are compatible with each other only if they are the same type.  */
 698
 699   if (TREE_CODE (t1) == ENUMERAL_TYPE && TREE_CODE (t2) != ENUMERAL_TYPE)
 700     t1 = c_common_type_for_size (TYPE_PRECISION (t1), TYPE_UNSIGNED (t1));
 701   else if (TREE_CODE (t2) == ENUMERAL_TYPE && TREE_CODE (t1) != ENUMERAL_TYPE)
 702     t2 = c_common_type_for_size (TYPE_PRECISION (t2), TYPE_UNSIGNED (t2));
 703
 704   if (t1 == t2)
 705     return 1;
 706
 707   /* Different classes of types can't be compatible.  */
 708
 709   if (TREE_CODE (t1) != TREE_CODE (t2))
 710     return 0;
 711
 712   /* Qualifiers must match. C99 6.7.3p9 */
 713
 714   if (TYPE_QUALS (t1) != TYPE_QUALS (t2))
 715     return 0;
 716
 717   /* Allow for two different type nodes which have essentially the same
 718      definition.  Note that we already checked for equality of the type
 719      qualifiers (just above).  */
 720
 721   if (TREE_CODE (t1) != ARRAY_TYPE
 722       && TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
 723     return 1;
 724
 725   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
 726   if (!(attrval = targetm.comp_type_attributes (t1, t2)))
 727      return 0;
 728
 729   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
 730   val = 0;
 731
 732   switch (TREE_CODE (t1))
 733     {
 734     case POINTER_TYPE:
 735       /* Do not remove mode or aliasing information.  */
 736       if (TYPE_MODE (t1) != TYPE_MODE (t2)
 737           || TYPE_REF_CAN_ALIAS_ALL (t1) != TYPE_REF_CAN_ALIAS_ALL (t2))
 738         break;
 739       val = (TREE_TYPE (t1) == TREE_TYPE (t2)
 740              ? 1 : comptypes (TREE_TYPE (t1), TREE_TYPE (t2)));
 741       break;
 742
 743     case FUNCTION_TYPE:
 744       val = function_types_compatible_p (t1, t2);
 745       break;
 746
 747     case ARRAY_TYPE:
 748       {
 749         tree d1 = TYPE_DOMAIN (t1);
 750         tree d2 = TYPE_DOMAIN (t2);
 751         bool d1_variable, d2_variable;
 752         bool d1_zero, d2_zero;
 753         val = 1;
 754
 755         /* Target types must match incl. qualifiers.  */
 756         if (TREE_TYPE (t1) != TREE_TYPE (t2)
 757             && 0 == (val = comptypes (TREE_TYPE (t1), TREE_TYPE (t2))))
 758           return 0;
 759
 760         /* Sizes must match unless one is missing or variable.  */
 761         if (d1 == 0 || d2 == 0 || d1 == d2)
 762           break;
 763
 764         d1_zero = !TYPE_MAX_VALUE (d1);
 765         d2_zero = !TYPE_MAX_VALUE (d2);
 766
 767         d1_variable = (!d1_zero
 768                        && (TREE_CODE (TYPE_MIN_VALUE (d1)) != INTEGER_CST
 769                            || TREE_CODE (TYPE_MAX_VALUE (d1)) != INTEGER_CST));
 770         d2_variable = (!d2_zero
 771                        && (TREE_CODE (TYPE_MIN_VALUE (d2)) != INTEGER_CST
 772                            || TREE_CODE (TYPE_MAX_VALUE (d2)) != INTEGER_CST));
 773
 774         if (d1_variable || d2_variable)
 775           break;
 776         if (d1_zero && d2_zero)
 777           break;
 778         if (d1_zero || d2_zero
 779             || !tree_int_cst_equal (TYPE_MIN_VALUE (d1), TYPE_MIN_VALUE (d2))
 780             || !tree_int_cst_equal (TYPE_MAX_VALUE (d1), TYPE_MAX_VALUE (d2)))
 781           val = 0;
 782
 783         break;
 784       }
 785
 786     case ENUMERAL_TYPE:
 787     case RECORD_TYPE:
 788     case UNION_TYPE:
 789       if (val != 1 && !same_translation_unit_p (t1, t2))
 790         val = tagged_types_tu_compatible_p (t1, t2);
 791       break;
 792
 793     case VECTOR_TYPE:
 794       val = TYPE_VECTOR_SUBPARTS (t1) == TYPE_VECTOR_SUBPARTS (t2)
 795             && comptypes (TREE_TYPE (t1), TREE_TYPE (t2));
 796       break;
 797
 798     default:
 799       break;
 800     }
 801   return attrval == 2 && val == 1 ? 2 : val;
 802 }
 803
 804 /* Return 1 if TTL and TTR are pointers to types that are equivalent,
 805    ignoring their qualifiers.  */
 806
 807 static int
 808 comp_target_types (tree ttl, tree ttr)
 809 {
 810   int val;
 811   tree mvl, mvr;
 812
 813   /* Do not lose qualifiers on element types of array types that are
 814      pointer targets by taking their TYPE_MAIN_VARIANT.  */
 815   mvl = TREE_TYPE (ttl);
 816   mvr = TREE_TYPE (ttr);
 817   if (TREE_CODE (mvl) != ARRAY_TYPE)
 818     mvl = TYPE_MAIN_VARIANT (mvl);
 819   if (TREE_CODE (mvr) != ARRAY_TYPE)
 820     mvr = TYPE_MAIN_VARIANT (mvr);
 821   val = comptypes (mvl, mvr);
 822
 823   if (val == 2 && pedantic)
 824     pedwarn ("types are not quite compatible");
 825   return val;
 826 }
 827 \f
 828 /* Subroutines of `comptypes'.  */
 829
 830 /* Determine whether two trees derive from the same translation unit.
 831    If the CONTEXT chain ends in a null, that tree's context is still
 832    being parsed, so if two trees have context chains ending in null,
 833    they're in the same translation unit.  */
 834 int
 835 same_translation_unit_p (tree t1, tree t2)
 836 {
 837   while (t1 && TREE_CODE (t1) != TRANSLATION_UNIT_DECL)
 838     switch (TREE_CODE_CLASS (TREE_CODE (t1)))
 839       {
 840       case tcc_declaration:
 841         t1 = DECL_CONTEXT (t1); break;
 842       case tcc_type:
 843         t1 = TYPE_CONTEXT (t1); break;
 844       case tcc_exceptional:
 845         t1 = BLOCK_SUPERCONTEXT (t1); break;  /* assume block */
 846       default: gcc_unreachable ();
 847       }
 848
 849   while (t2 && TREE_CODE (t2) != TRANSLATION_UNIT_DECL)
 850     switch (TREE_CODE_CLASS (TREE_CODE (t2)))
 851       {
 852       case tcc_declaration:
 853         t2 = DECL_CONTEXT (t2); break;
 854       case tcc_type:
 855         t2 = TYPE_CONTEXT (t2); break;
 856       case tcc_exceptional:
 857         t2 = BLOCK_SUPERCONTEXT (t2); break;  /* assume block */
 858       default: gcc_unreachable ();
 859       }
 860
 861   return t1 == t2;
 862 }
 863
 864 /* The C standard says that two structures in different translation
 865    units are compatible with each other only if the types of their
 866    fields are compatible (among other things).  So, consider two copies
 867    of this structure:  */
 868
 869 struct tagged_tu_seen {
 870   const struct tagged_tu_seen * next;
 871   tree t1;
 872   tree t2;
 873 };
 874
 875 /* Can they be compatible with each other?  We choose to break the
 876    recursion by allowing those types to be compatible.  */
 877
 878 static const struct tagged_tu_seen * tagged_tu_seen_base;
 879
 880 /* Return 1 if two 'struct', 'union', or 'enum' types T1 and T2 are
 881    compatible.  If the two types are not the same (which has been
 882    checked earlier), this can only happen when multiple translation
 883    units are being compiled.  See C99 6.2.7 paragraph 1 for the exact
 884    rules.  */
 885
 886 static int
 887 tagged_types_tu_compatible_p (tree t1, tree t2)
 888 {
 889   tree s1, s2;
 890   bool needs_warning = false;
 891
 892   /* We have to verify that the tags of the types are the same.  This
 893      is harder than it looks because this may be a typedef, so we have
 894      to go look at the original type.  It may even be a typedef of a
 895      typedef...
 896      In the case of compiler-created builtin structs the TYPE_DECL
 897      may be a dummy, with no DECL_ORIGINAL_TYPE.  Don't fault.  */
 898   while (TYPE_NAME (t1)
 899          && TREE_CODE (TYPE_NAME (t1)) == TYPE_DECL
 900          && DECL_ORIGINAL_TYPE (TYPE_NAME (t1)))
 901     t1 = DECL_ORIGINAL_TYPE (TYPE_NAME (t1));
 902
 903   while (TYPE_NAME (t2)
 904          && TREE_CODE (TYPE_NAME (t2)) == TYPE_DECL
 905          && DECL_ORIGINAL_TYPE (TYPE_NAME (t2)))
 906     t2 = DECL_ORIGINAL_TYPE (TYPE_NAME (t2));
 907
 908   /* C90 didn't have the requirement that the two tags be the same.  */
 909   if (flag_isoc99 && TYPE_NAME (t1) != TYPE_NAME (t2))
 910     return 0;
 911
 912   /* C90 didn't say what happened if one or both of the types were
 913      incomplete; we choose to follow C99 rules here, which is that they
 914      are compatible.  */
 915   if (TYPE_SIZE (t1) == NULL
 916       || TYPE_SIZE (t2) == NULL)
 917     return 1;
 918
 919   {
 920     const struct tagged_tu_seen * tts_i;
 921     for (tts_i = tagged_tu_seen_base; tts_i != NULL; tts_i = tts_i->next)
 922       if (tts_i->t1 == t1 && tts_i->t2 == t2)
 923         return 1;
 924   }
 925
 926   switch (TREE_CODE (t1))
 927     {
 928     case ENUMERAL_TYPE:
 929       {
 930
 931         /* Speed up the case where the type values are in the same order.  */
 932         tree tv1 = TYPE_VALUES (t1);
 933         tree tv2 = TYPE_VALUES (t2);
 934
 935         if (tv1 == tv2)
 936           return 1;
 937
 938         for (;tv1 && tv2; tv1 = TREE_CHAIN (tv1), tv2 = TREE_CHAIN (tv2))
 939           {
 940             if (TREE_PURPOSE (tv1) != TREE_PURPOSE (tv2))
 941               break;
 942             if (simple_cst_equal (TREE_VALUE (tv1), TREE_VALUE (tv2)) != 1)
 943               return 0;
 944           }
 945
 946         if (tv1 == NULL_TREE && tv2 == NULL_TREE)
 947           return 1;
 948         if (tv1 == NULL_TREE || tv2 == NULL_TREE)
 949           return 0;
 950
 951         if (list_length (TYPE_VALUES (t1)) != list_length (TYPE_VALUES (t2)))
 952           return 0;
 953
 954         for (s1 = TYPE_VALUES (t1); s1; s1 = TREE_CHAIN (s1))
 955           {
 956             s2 = purpose_member (TREE_PURPOSE (s1), TYPE_VALUES (t2));
 957             if (s2 == NULL
 958                 || simple_cst_equal (TREE_VALUE (s1), TREE_VALUE (s2)) != 1)
 959               return 0;
 960           }
 961         return 1;
 962       }
 963
 964     case UNION_TYPE:
 965       {
 966         if (list_length (TYPE_FIELDS (t1)) != list_length (TYPE_FIELDS (t2)))
 967           return 0;
 968
 969         for (s1 = TYPE_FIELDS (t1); s1; s1 = TREE_CHAIN (s1))
 970           {
 971             bool ok = false;
 972             struct tagged_tu_seen tts;
 973
 974             tts.next = tagged_tu_seen_base;
 975             tts.t1 = t1;
 976             tts.t2 = t2;
 977             tagged_tu_seen_base = &tts;
 978
 979             if (DECL_NAME (s1) != NULL)
 980               for (s2 = TYPE_FIELDS (t2); s2; s2 = TREE_CHAIN (s2))
 981                 if (DECL_NAME (s1) == DECL_NAME (s2))
 982                   {
 983                     int result;
 984                     result = comptypes (TREE_TYPE (s1), TREE_TYPE (s2));
 985                     if (result == 0)
 986                       break;
 987                     if (result == 2)
 988                       needs_warning = true;
 989
 990                     if (TREE_CODE (s1) == FIELD_DECL
 991                         && simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
 992                                              DECL_FIELD_BIT_OFFSET (s2)) != 1)
 993                       break;
 994
 995                     ok = true;
 996                     break;
 997                   }
 998             tagged_tu_seen_base = tts.next;
 999             if (!ok)
1000               return 0;
1001           }
1002         return needs_warning ? 2 : 1;
1003       }
1004
1005     case RECORD_TYPE:
1006       {
1007         struct tagged_tu_seen tts;
1008
1009         tts.next = tagged_tu_seen_base;
1010         tts.t1 = t1;
1011         tts.t2 = t2;
1012         tagged_tu_seen_base = &tts;
1013
1014         for (s1 = TYPE_FIELDS (t1), s2 = TYPE_FIELDS (t2);
1015              s1 && s2;
1016              s1 = TREE_CHAIN (s1), s2 = TREE_CHAIN (s2))
1017           {
1018             int result;
1019             if (TREE_CODE (s1) != TREE_CODE (s2)
1020                 || DECL_NAME (s1) != DECL_NAME (s2))
1021               break;
1022             result = comptypes (TREE_TYPE (s1), TREE_TYPE (s2));
1023             if (result == 0)
1024               break;
1025             if (result == 2)
1026               needs_warning = true;
1027
1028             if (TREE_CODE (s1) == FIELD_DECL
1029                 && simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
1030                                      DECL_FIELD_BIT_OFFSET (s2)) != 1)
1031               break;
1032           }
1033         tagged_tu_seen_base = tts.next;
1034         if (s1 && s2)
1035           return 0;
1036         return needs_warning ? 2 : 1;
1037       }
1038
1039     default:
1040       gcc_unreachable ();
1041     }
1042 }
1043
1044 /* Return 1 if two function types F1 and F2 are compatible.
1045    If either type specifies no argument types,
1046    the other must specify a fixed number of self-promoting arg types.
1047    Otherwise, if one type specifies only the number of arguments,
1048    the other must specify that number of self-promoting arg types.
1049    Otherwise, the argument types must match.  */
1050
1051 static int
1052 function_types_compatible_p (tree f1, tree f2)
1053 {
1054   tree args1, args2;
1055   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
1056   int val = 1;
1057   int val1;
1058   tree ret1, ret2;
1059
1060   ret1 = TREE_TYPE (f1);
1061   ret2 = TREE_TYPE (f2);
1062
1063   /* 'volatile' qualifiers on a function's return type used to mean
1064      the function is noreturn.  */
1065   if (TYPE_VOLATILE (ret1) != TYPE_VOLATILE (ret2))
1066     pedwarn ("function return types not compatible due to %<volatile%>");
1067   if (TYPE_VOLATILE (ret1))
1068     ret1 = build_qualified_type (TYPE_MAIN_VARIANT (ret1),
1069                                  TYPE_QUALS (ret1) & ~TYPE_QUAL_VOLATILE);
1070   if (TYPE_VOLATILE (ret2))
1071     ret2 = build_qualified_type (TYPE_MAIN_VARIANT (ret2),
1072                                  TYPE_QUALS (ret2) & ~TYPE_QUAL_VOLATILE);
1073   val = comptypes (ret1, ret2);
1074   if (val == 0)
1075     return 0;
1076
1077   args1 = TYPE_ARG_TYPES (f1);
1078   args2 = TYPE_ARG_TYPES (f2);
1079
1080   /* An unspecified parmlist matches any specified parmlist
1081      whose argument types don't need default promotions.  */
1082
1083   if (args1 == 0)
1084     {
1085       if (!self_promoting_args_p (args2))
1086         return 0;
1087       /* If one of these types comes from a non-prototype fn definition,
1088          compare that with the other type's arglist.
1089          If they don't match, ask for a warning (but no error).  */
1090       if (TYPE_ACTUAL_ARG_TYPES (f1)
1091           && 1 != type_lists_compatible_p (args2, TYPE_ACTUAL_ARG_TYPES (f1)))
1092         val = 2;
1093       return val;
1094     }
1095   if (args2 == 0)
1096     {
1097       if (!self_promoting_args_p (args1))
1098         return 0;
1099       if (TYPE_ACTUAL_ARG_TYPES (f2)
1100           && 1 != type_lists_compatible_p (args1, TYPE_ACTUAL_ARG_TYPES (f2)))
1101         val = 2;
1102       return val;
1103     }
1104
1105   /* Both types have argument lists: compare them and propagate results.  */
1106   val1 = type_lists_compatible_p (args1, args2);
1107   return val1 != 1 ? val1 : val;
1108 }
1109
1110 /* Check two lists of types for compatibility,
1111    returning 0 for incompatible, 1 for compatible,
1112    or 2 for compatible with warning.  */
1113
1114 static int
1115 type_lists_compatible_p (tree args1, tree args2)
1116 {
1117   /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
1118   int val = 1;
1119   int newval = 0;
1120
1121   while (1)
1122     {
1123       tree a1, mv1, a2, mv2;
1124       if (args1 == 0 && args2 == 0)
1125         return val;
1126       /* If one list is shorter than the other,
1127          they fail to match.  */
1128       if (args1 == 0 || args2 == 0)
1129         return 0;
1130       mv1 = a1 = TREE_VALUE (args1);
1131       mv2 = a2 = TREE_VALUE (args2);
1132       if (mv1 && mv1 != error_mark_node && TREE_CODE (mv1) != ARRAY_TYPE)
1133         mv1 = TYPE_MAIN_VARIANT (mv1);
1134       if (mv2 && mv2 != error_mark_node && TREE_CODE (mv2) != ARRAY_TYPE)
1135         mv2 = TYPE_MAIN_VARIANT (mv2);
1136       /* A null pointer instead of a type
1137          means there is supposed to be an argument
1138          but nothing is specified about what type it has.
1139          So match anything that self-promotes.  */
1140       if (a1 == 0)
1141         {
1142           if (c_type_promotes_to (a2) != a2)
1143             return 0;
1144         }
1145       else if (a2 == 0)
1146         {
1147           if (c_type_promotes_to (a1) != a1)
1148             return 0;
1149         }
1150       /* If one of the lists has an error marker, ignore this arg.  */
1151       else if (TREE_CODE (a1) == ERROR_MARK
1152                || TREE_CODE (a2) == ERROR_MARK)
1153         ;
1154       else if (!(newval = comptypes (mv1, mv2)))
1155         {
1156           /* Allow  wait (union {union wait *u; int *i} *)
1157              and  wait (union wait *)  to be compatible.  */
1158           if (TREE_CODE (a1) == UNION_TYPE
1159               && (TYPE_NAME (a1) == 0
1160                   || TYPE_TRANSPARENT_UNION (a1))
1161               && TREE_CODE (TYPE_SIZE (a1)) == INTEGER_CST
1162               && tree_int_cst_equal (TYPE_SIZE (a1),
1163                                      TYPE_SIZE (a2)))
1164             {
1165               tree memb;
1166               for (memb = TYPE_FIELDS (a1);
1167                    memb; memb = TREE_CHAIN (memb))
1168                 {
1169                   tree mv3 = TREE_TYPE (memb);
1170                   if (mv3 && mv3 != error_mark_node
1171                       && TREE_CODE (mv3) != ARRAY_TYPE)
1172                     mv3 = TYPE_MAIN_VARIANT (mv3);
1173                   if (comptypes (mv3, mv2))
1174                     break;
1175                 }
1176               if (memb == 0)
1177                 return 0;
1178             }
1179           else if (TREE_CODE (a2) == UNION_TYPE
1180                    && (TYPE_NAME (a2) == 0
1181                        || TYPE_TRANSPARENT_UNION (a2))
1182                    && TREE_CODE (TYPE_SIZE (a2)) == INTEGER_CST
1183                    && tree_int_cst_equal (TYPE_SIZE (a2),
1184                                           TYPE_SIZE (a1)))
1185             {
1186               tree memb;
1187               for (memb = TYPE_FIELDS (a2);
1188                    memb; memb = TREE_CHAIN (memb))
1189                 {
1190                   tree mv3 = TREE_TYPE (memb);
1191                   if (mv3 && mv3 != error_mark_node
1192                       && TREE_CODE (mv3) != ARRAY_TYPE)
1193                     mv3 = TYPE_MAIN_VARIANT (mv3);
1194                   if (comptypes (mv3, mv1))
1195                     break;
1196                 }
1197               if (memb == 0)
1198                 return 0;
1199             }
1200           else
1201             return 0;
1202         }
1203
1204       /* comptypes said ok, but record if it said to warn.  */
1205       if (newval > val)
1206         val = newval;
1207
1208       args1 = TREE_CHAIN (args1);
1209       args2 = TREE_CHAIN (args2);
1210     }
1211 }
1212 \f
1213 /* Compute the size to increment a pointer by.  */
1214
1215 static tree
1216 c_size_in_bytes (tree type)
1217 {
1218   enum tree_code code = TREE_CODE (type);
1219
1220   if (code == FUNCTION_TYPE || code == VOID_TYPE || code == ERROR_MARK)
1221     return size_one_node;
1222
1223   if (!COMPLETE_OR_VOID_TYPE_P (type))
1224     {
1225       error ("arithmetic on pointer to an incomplete type");
1226       return size_one_node;
1227     }
1228
1229   /* Convert in case a char is more than one unit.  */
1230   return size_binop (CEIL_DIV_EXPR, TYPE_SIZE_UNIT (type),
1231                      size_int (TYPE_PRECISION (char_type_node)
1232                                / BITS_PER_UNIT));
1233 }
1234 \f
1235 /* Return either DECL or its known constant value (if it has one).  */
1236
1237 tree
1238 decl_constant_value (tree decl)
1239 {
1240   if (/* Don't change a variable array bound or initial value to a constant
1241          in a place where a variable is invalid.  Note that DECL_INITIAL
1242          isn't valid for a PARM_DECL.  */
1243       current_function_decl != 0
1244       && TREE_CODE (decl) != PARM_DECL
1245       && !TREE_THIS_VOLATILE (decl)
1246       && TREE_READONLY (decl)
1247       && DECL_INITIAL (decl) != 0
1248       && TREE_CODE (DECL_INITIAL (decl)) != ERROR_MARK
1249       /* This is invalid if initial value is not constant.
1250          If it has either a function call, a memory reference,
1251          or a variable, then re-evaluating it could give different results.  */
1252       && TREE_CONSTANT (DECL_INITIAL (decl))
1253       /* Check for cases where this is sub-optimal, even though valid.  */
1254       && TREE_CODE (DECL_INITIAL (decl)) != CONSTRUCTOR)
1255     return DECL_INITIAL (decl);
1256   return decl;
1257 }
1258
1259 /* Return either DECL or its known constant value (if it has one), but
1260    return DECL if pedantic or DECL has mode BLKmode.  This is for
1261    bug-compatibility with the old behavior of decl_constant_value
1262    (before GCC 3.0); every use of this function is a bug and it should
1263    be removed before GCC 3.1.  It is not appropriate to use pedantic
1264    in a way that affects optimization, and BLKmode is probably not the
1265    right test for avoiding misoptimizations either.  */
1266
1267 static tree
1268 decl_constant_value_for_broken_optimization (tree decl)
1269 {
1270   tree ret;
1271
1272   if (pedantic || DECL_MODE (decl) == BLKmode)
1273     return decl;
1274
1275   ret = decl_constant_value (decl);
1276   /* Avoid unwanted tree sharing between the initializer and current
1277      function's body where the tree can be modified e.g. by the
1278      gimplifier.  */
1279   if (ret != decl && TREE_STATIC (decl))
1280     ret = unshare_expr (ret);
1281   return ret;
1282 }
1283
1284 /* Convert the array expression EXP to a pointer.  */
1285 static tree
1286 array_to_pointer_conversion (tree exp)
1287 {
1288   tree orig_exp = exp;
1289   tree type = TREE_TYPE (exp);
1290   tree adr;
1291   tree restype = TREE_TYPE (type);
1292   tree ptrtype;
1293
1294   gcc_assert (TREE_CODE (type) == ARRAY_TYPE);
1295
1296   STRIP_TYPE_NOPS (exp);
1297
1298   if (TREE_NO_WARNING (orig_exp))
1299     TREE_NO_WARNING (exp) = 1;
1300
1301   ptrtype = build_pointer_type (restype);
1302
1303   if (TREE_CODE (exp) == INDIRECT_REF)
1304     return convert (ptrtype, TREE_OPERAND (exp, 0));
1305
1306   if (TREE_CODE (exp) == VAR_DECL)
1307     {
1308       /* We are making an ADDR_EXPR of ptrtype.  This is a valid
1309          ADDR_EXPR because it's the best way of representing what
1310          happens in C when we take the address of an array and place
1311          it in a pointer to the element type.  */
1312       adr = build1 (ADDR_EXPR, ptrtype, exp);
1313       if (!c_mark_addressable (exp))
1314         return error_mark_node;
1315       TREE_SIDE_EFFECTS (adr) = 0;   /* Default would be, same as EXP.  */
1316       return adr;
1317     }
1318
1319   /* This way is better for a COMPONENT_REF since it can
1320      simplify the offset for a component.  */
1321   adr = build_unary_op (ADDR_EXPR, exp, 1);
1322   return convert (ptrtype, adr);
1323 }
1324
1325 /* Convert the function expression EXP to a pointer.  */
1326 static tree
1327 function_to_pointer_conversion (tree exp)
1328 {
1329   tree orig_exp = exp;
1330
1331   gcc_assert (TREE_CODE (TREE_TYPE (exp)) == FUNCTION_TYPE);
1332
1333   STRIP_TYPE_NOPS (exp);
1334
1335   if (TREE_NO_WARNING (orig_exp))
1336     TREE_NO_WARNING (exp) = 1;
1337
1338   return build_unary_op (ADDR_EXPR, exp, 0);
1339 }
1340
1341 /* Perform the default conversion of arrays and functions to pointers.
1342    Return the result of converting EXP.  For any other expression, just
1343    return EXP after removing NOPs.  */
1344
1345 struct c_expr
1346 default_function_array_conversion (struct c_expr exp)
1347 {
1348   tree orig_exp = exp.value;
1349   tree type = TREE_TYPE (exp.value);
1350   enum tree_code code = TREE_CODE (type);
1351
1352   switch (code)
1353     {
1354     case ARRAY_TYPE:
1355       {
1356         bool not_lvalue = false;
1357         bool lvalue_array_p;
1358
1359         while ((TREE_CODE (exp.value) == NON_LVALUE_EXPR
1360                 || TREE_CODE (exp.value) == NOP_EXPR)
1361                && TREE_TYPE (TREE_OPERAND (exp.value, 0)) == type)
1362           {
1363             if (TREE_CODE (exp.value) == NON_LVALUE_EXPR)
1364               not_lvalue = true;
1365             exp.value = TREE_OPERAND (exp.value, 0);
1366           }
1367
1368         if (TREE_NO_WARNING (orig_exp))
1369           TREE_NO_WARNING (exp.value) = 1;
1370
1371         lvalue_array_p = !not_lvalue && lvalue_p (exp.value);
1372         if (!flag_isoc99 && !lvalue_array_p)
1373           {
1374             /* Before C99, non-lvalue arrays do not decay to pointers.
1375                Normally, using such an array would be invalid; but it can
1376                be used correctly inside sizeof or as a statement expression.
1377                Thus, do not give an error here; an error will result later.  */
1378             return exp;
1379           }
1380
1381         exp.value = array_to_pointer_conversion (exp.value);
1382       }
1383       break;
1384     case FUNCTION_TYPE:
1385       exp.value = function_to_pointer_conversion (exp.value);
1386       break;
1387     default:
1388       STRIP_TYPE_NOPS (exp.value);
1389       if (TREE_NO_WARNING (orig_exp))
1390         TREE_NO_WARNING (exp.value) = 1;
1391       break;
1392     }
1393
1394   return exp;
1395 }
1396
1397
1398 /* EXP is an expression of integer type.  Apply the integer promotions
1399    to it and return the promoted value.  */
1400
1401 tree
1402 perform_integral_promotions (tree exp)
1403 {
1404   tree type = TREE_TYPE (exp);
1405   enum tree_code code = TREE_CODE (type);
1406
1407   gcc_assert (INTEGRAL_TYPE_P (type));
1408
1409   /* Normally convert enums to int,
1410      but convert wide enums to something wider.  */
1411   if (code == ENUMERAL_TYPE)
1412     {
1413       type = c_common_type_for_size (MAX (TYPE_PRECISION (type),
1414                                           TYPE_PRECISION (integer_type_node)),
1415                                      ((TYPE_PRECISION (type)
1416                                        >= TYPE_PRECISION (integer_type_node))
1417                                       && TYPE_UNSIGNED (type)));
1418
1419       return convert (type, exp);
1420     }
1421
1422   /* ??? This should no longer be needed now bit-fields have their
1423      proper types.  */
1424   if (TREE_CODE (exp) == COMPONENT_REF
1425       && DECL_C_BIT_FIELD (TREE_OPERAND (exp, 1))
1426       /* If it's thinner than an int, promote it like a
1427          c_promoting_integer_type_p, otherwise leave it alone.  */
1428       && 0 > compare_tree_int (DECL_SIZE (TREE_OPERAND (exp, 1)),
1429                                TYPE_PRECISION (integer_type_node)))
1430     return convert (integer_type_node, exp);
1431
1432   if (c_promoting_integer_type_p (type))
1433     {
1434       /* Preserve unsignedness if not really getting any wider.  */
1435       if (TYPE_UNSIGNED (type)
1436           && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
1437         return convert (unsigned_type_node, exp);
1438
1439       return convert (integer_type_node, exp);
1440     }
1441
1442   return exp;
1443 }
1444
1445
1446 /* Perform default promotions for C data used in expressions.
1447    Enumeral types or short or char are converted to int.
1448    In addition, manifest constants symbols are replaced by their values.  */
1449
1450 tree
1451 default_conversion (tree exp)
1452 {
1453   tree orig_exp;
1454   tree type = TREE_TYPE (exp);
1455   enum tree_code code = TREE_CODE (type);
1456
1457   /* Functions and arrays have been converted during parsing.  */
1458   gcc_assert (code != FUNCTION_TYPE);
1459   if (code == ARRAY_TYPE)
1460     return exp;
1461
1462   /* Constants can be used directly unless they're not loadable.  */
1463   if (TREE_CODE (exp) == CONST_DECL)
1464     exp = DECL_INITIAL (exp);
1465
1466   /* Replace a nonvolatile const static variable with its value unless
1467      it is an array, in which case we must be sure that taking the
1468      address of the array produces consistent results.  */
1469   else if (optimize && TREE_CODE (exp) == VAR_DECL && code != ARRAY_TYPE)
1470     {
1471       exp = decl_constant_value_for_broken_optimization (exp);
1472       type = TREE_TYPE (exp);
1473     }
1474
1475   /* Strip no-op conversions.  */
1476   orig_exp = exp;
1477   STRIP_TYPE_NOPS (exp);
1478
1479   if (TREE_NO_WARNING (orig_exp))
1480     TREE_NO_WARNING (exp) = 1;
1481
1482   if (INTEGRAL_TYPE_P (type))
1483     return perform_integral_promotions (exp);
1484
1485   if (code == VOID_TYPE)
1486     {
1487       error ("void value not ignored as it ought to be");
1488       return error_mark_node;
1489     }
1490   return exp;
1491 }
1492 \f
1493 /* Look up COMPONENT in a structure or union DECL.
1494
1495    If the component name is not found, returns NULL_TREE.  Otherwise,
1496    the return value is a TREE_LIST, with each TREE_VALUE a FIELD_DECL
1497    stepping down the chain to the component, which is in the last
1498    TREE_VALUE of the list.  Normally the list is of length one, but if
1499    the component is embedded within (nested) anonymous structures or
1500    unions, the list steps down the chain to the component.  */
1501
1502 static tree
1503 lookup_field (tree decl, tree component)
1504 {
1505   tree type = TREE_TYPE (decl);
1506   tree field;
1507
1508   /* If TYPE_LANG_SPECIFIC is set, then it is a sorted array of pointers
1509      to the field elements.  Use a binary search on this array to quickly
1510      find the element.  Otherwise, do a linear search.  TYPE_LANG_SPECIFIC
1511      will always be set for structures which have many elements.  */
1512
1513   if (TYPE_LANG_SPECIFIC (type) && TYPE_LANG_SPECIFIC (type)->s)
1514     {
1515       int bot, top, half;
1516       tree *field_array = &TYPE_LANG_SPECIFIC (type)->s->elts[0];
1517
1518       field = TYPE_FIELDS (type);
1519       bot = 0;
1520       top = TYPE_LANG_SPECIFIC (type)->s->len;
1521       while (top - bot > 1)
1522         {
1523           half = (top - bot + 1) >> 1;
1524           field = field_array[bot+half];
1525
1526           if (DECL_NAME (field) == NULL_TREE)
1527             {
1528               /* Step through all anon unions in linear fashion.  */
1529               while (DECL_NAME (field_array[bot]) == NULL_TREE)
1530                 {
1531                   field = field_array[bot++];
1532                   if (TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
1533                       || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
1534                     {
1535                       tree anon = lookup_field (field, component);
1536
1537                       if (anon)
1538                         return tree_cons (NULL_TREE, field, anon);
1539                     }
1540                 }
1541
1542               /* Entire record is only anon unions.  */
1543               if (bot > top)
1544                 return NULL_TREE;
1545
1546               /* Restart the binary search, with new lower bound.  */
1547               continue;
1548             }
1549
1550           if (DECL_NAME (field) == component)
1551             break;
1552           if (DECL_NAME (field) < component)
1553             bot += half;
1554           else
1555             top = bot + half;
1556         }
1557
1558       if (DECL_NAME (field_array[bot]) == component)
1559         field = field_array[bot];
1560       else if (DECL_NAME (field) != component)
1561         return NULL_TREE;
1562     }
1563   else
1564     {
1565       for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1566         {
1567           if (DECL_NAME (field) == NULL_TREE
1568               && (TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
1569                   || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE))
1570             {
1571               tree anon = lookup_field (field, component);
1572
1573               if (anon)
1574                 return tree_cons (NULL_TREE, field, anon);
1575             }
1576
1577           if (DECL_NAME (field) == component)
1578             break;
1579         }
1580
1581       if (field == NULL_TREE)
1582         return NULL_TREE;
1583     }
1584
1585   return tree_cons (NULL_TREE, field, NULL_TREE);
1586 }
1587
1588 /* Make an expression to refer to the COMPONENT field of
1589    structure or union value DATUM.  COMPONENT is an IDENTIFIER_NODE.  */
1590
1591 tree
1592 build_component_ref (tree datum, tree component)
1593 {
1594   tree type = TREE_TYPE (datum);
1595   enum tree_code code = TREE_CODE (type);
1596   tree field = NULL;
1597   tree ref;
1598
1599   if (!objc_is_public (datum, component))
1600     return error_mark_node;
1601
1602   /* See if there is a field or component with name COMPONENT.  */
1603
1604   if (code == RECORD_TYPE || code == UNION_TYPE)
1605     {
1606       if (!COMPLETE_TYPE_P (type))
1607         {
1608           c_incomplete_type_error (NULL_TREE, type);
1609           return error_mark_node;
1610         }
1611
1612       field = lookup_field (datum, component);
1613
1614       if (!field)
1615         {
1616           error ("%qT has no member named %qE", type, component);
1617           return error_mark_node;
1618         }
1619
1620       /* Chain the COMPONENT_REFs if necessary down to the FIELD.
1621          This might be better solved in future the way the C++ front
1622          end does it - by giving the anonymous entities each a
1623          separate name and type, and then have build_component_ref
1624          recursively call itself.  We can't do that here.  */
1625       do
1626         {
1627           tree subdatum = TREE_VALUE (field);
1628
1629           if (TREE_TYPE (subdatum) == error_mark_node)
1630             return error_mark_node;
1631
1632           ref = build3 (COMPONENT_REF, TREE_TYPE (subdatum), datum, subdatum,
1633                         NULL_TREE);
1634           if (TREE_READONLY (datum) || TREE_READONLY (subdatum))
1635             TREE_READONLY (ref) = 1;
1636           if (TREE_THIS_VOLATILE (datum) || TREE_THIS_VOLATILE (subdatum))
1637             TREE_THIS_VOLATILE (ref) = 1;
1638
1639           if (TREE_DEPRECATED (subdatum))
1640             warn_deprecated_use (subdatum);
1641
1642           datum = ref;
1643
1644           field = TREE_CHAIN (field);
1645         }
1646       while (field);
1647
1648       return ref;
1649     }
1650   else if (code != ERROR_MARK)
1651     error ("request for member %qE in something not a structure or union",
1652            component);
1653
1654   return error_mark_node;
1655 }
1656 \f
1657 /* Given an expression PTR for a pointer, return an expression
1658    for the value pointed to.
1659    ERRORSTRING is the name of the operator to appear in error messages.  */
1660
1661 tree
1662 build_indirect_ref (tree ptr, const char *errorstring)
1663 {
1664   tree pointer = default_conversion (ptr);
1665   tree type = TREE_TYPE (pointer);
1666
1667   if (TREE_CODE (type) == POINTER_TYPE)
1668     {
1669       if (TREE_CODE (pointer) == ADDR_EXPR
1670           && (TREE_TYPE (TREE_OPERAND (pointer, 0))
1671               == TREE_TYPE (type)))
1672         return TREE_OPERAND (pointer, 0);
1673       else
1674         {
1675           tree t = TREE_TYPE (type);
1676           tree ref;
1677
1678           ref = build1 (INDIRECT_REF, t, pointer);
1679
1680           if (!COMPLETE_OR_VOID_TYPE_P (t) && TREE_CODE (t) != ARRAY_TYPE)
1681             {
1682               error ("dereferencing pointer to incomplete type");
1683               return error_mark_node;
1684             }
1685           if (VOID_TYPE_P (t) && skip_evaluation == 0)
1686             warning (0, "dereferencing %<void *%> pointer");
1687
1688           /* We *must* set TREE_READONLY when dereferencing a pointer to const,
1689              so that we get the proper error message if the result is used
1690              to assign to.  Also, &* is supposed to be a no-op.
1691              And ANSI C seems to specify that the type of the result
1692              should be the const type.  */
1693           /* A de-reference of a pointer to const is not a const.  It is valid
1694              to change it via some other pointer.  */
1695           TREE_READONLY (ref) = TYPE_READONLY (t);
1696           TREE_SIDE_EFFECTS (ref)
1697             = TYPE_VOLATILE (t) || TREE_SIDE_EFFECTS (pointer);
1698           TREE_THIS_VOLATILE (ref) = TYPE_VOLATILE (t);
1699           return ref;
1700         }
1701     }
1702   else if (TREE_CODE (pointer) != ERROR_MARK)
1703     error ("invalid type argument of %qs", errorstring);
1704   return error_mark_node;
1705 }
1706
1707 /* This handles expressions of the form "a[i]", which denotes
1708    an array reference.
1709
1710    This is logically equivalent in C to *(a+i), but we may do it differently.
1711    If A is a variable or a member, we generate a primitive ARRAY_REF.
1712    This avoids forcing the array out of registers, and can work on
1713    arrays that are not lvalues (for example, members of structures returned
1714    by functions).  */
1715
1716 tree
1717 build_array_ref (tree array, tree index)
1718 {
1719   bool swapped = false;
1720   if (TREE_TYPE (array) == error_mark_node
1721       || TREE_TYPE (index) == error_mark_node)
1722     return error_mark_node;
1723
1724   if (TREE_CODE (TREE_TYPE (array)) != ARRAY_TYPE
1725       && TREE_CODE (TREE_TYPE (array)) != POINTER_TYPE)
1726     {
1727       tree temp;
1728       if (TREE_CODE (TREE_TYPE (index)) != ARRAY_TYPE
1729           && TREE_CODE (TREE_TYPE (index)) != POINTER_TYPE)
1730         {
1731           error ("subscripted value is neither array nor pointer");
1732           return error_mark_node;
1733         }
1734       temp = array;
1735       array = index;
1736       index = temp;
1737       swapped = true;
1738     }
1739
1740   if (!INTEGRAL_TYPE_P (TREE_TYPE (index)))
1741     {
1742       error ("array subscript is not an integer");
1743       return error_mark_node;
1744     }
1745
1746   if (TREE_CODE (TREE_TYPE (TREE_TYPE (array))) == FUNCTION_TYPE)
1747     {
1748       error ("subscripted value is pointer to function");
1749       return error_mark_node;
1750     }
1751
1752   /* Subscripting with type char is likely to lose on a machine where
1753      chars are signed.  So warn on any machine, but optionally.  Don't
1754      warn for unsigned char since that type is safe.  Don't warn for
1755      signed char because anyone who uses that must have done so
1756      deliberately.  ??? Existing practice has also been to warn only
1757      when the char index is syntactically the index, not for
1758      char[array].  */
1759   if (!swapped
1760       && TYPE_MAIN_VARIANT (TREE_TYPE (index)) == char_type_node)
1761     warning (OPT_Wchar_subscripts, "array subscript has type %<char%>");
1762
1763   /* Apply default promotions *after* noticing character types.  */
1764   index = default_conversion (index);
1765
1766   gcc_assert (TREE_CODE (TREE_TYPE (index)) == INTEGER_TYPE);
1767
1768   if (TREE_CODE (TREE_TYPE (array)) == ARRAY_TYPE)
1769     {
1770       tree rval, type;
1771
1772       /* An array that is indexed by a non-constant
1773          cannot be stored in a register; we must be able to do
1774          address arithmetic on its address.
1775          Likewise an array of elements of variable size.  */
1776       if (TREE_CODE (index) != INTEGER_CST
1777           || (COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (array)))
1778               && TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (array)))) != INTEGER_CST))
1779         {
1780           if (!c_mark_addressable (array))
1781             return error_mark_node;
1782         }
1783       /* An array that is indexed by a constant value which is not within
1784          the array bounds cannot be stored in a register either; because we
1785          would get a crash in store_bit_field/extract_bit_field when trying
1786          to access a non-existent part of the register.  */
1787       if (TREE_CODE (index) == INTEGER_CST
1788           && TYPE_DOMAIN (TREE_TYPE (array))
1789           && !int_fits_type_p (index, TYPE_DOMAIN (TREE_TYPE (array))))
1790         {
1791           if (!c_mark_addressable (array))
1792             return error_mark_node;
1793         }
1794
1795       if (pedantic)
1796         {
1797           tree foo = array;
1798           while (TREE_CODE (foo) == COMPONENT_REF)
1799             foo = TREE_OPERAND (foo, 0);
1800           if (TREE_CODE (foo) == VAR_DECL && C_DECL_REGISTER (foo))
1801             pedwarn ("ISO C forbids subscripting %<register%> array");
1802           else if (!flag_isoc99 && !lvalue_p (foo))
1803             pedwarn ("ISO C90 forbids subscripting non-lvalue array");
1804         }
1805
1806       type = TREE_TYPE (TREE_TYPE (array));
1807       if (TREE_CODE (type) != ARRAY_TYPE)
1808         type = TYPE_MAIN_VARIANT (type);
1809       rval = build4 (ARRAY_REF, type, array, index, NULL_TREE, NULL_TREE);
1810       /* Array ref is const/volatile if the array elements are
1811          or if the array is.  */
1812       TREE_READONLY (rval)
1813         |= (TYPE_READONLY (TREE_TYPE (TREE_TYPE (array)))
1814             | TREE_READONLY (array));
1815       TREE_SIDE_EFFECTS (rval)
1816         |= (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (array)))
1817             | TREE_SIDE_EFFECTS (array));
1818       TREE_THIS_VOLATILE (rval)
1819         |= (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (array)))
1820             /* This was added by rms on 16 Nov 91.
1821                It fixes  vol struct foo *a;  a->elts[1]
1822                in an inline function.
1823                Hope it doesn't break something else.  */
1824             | TREE_THIS_VOLATILE (array));
1825       return require_complete_type (fold (rval));
1826     }
1827   else
1828     {
1829       tree ar = default_conversion (array);
1830
1831       if (ar == error_mark_node)
1832         return ar;
1833
1834       gcc_assert (TREE_CODE (TREE_TYPE (ar)) == POINTER_TYPE);
1835       gcc_assert (TREE_CODE (TREE_TYPE (TREE_TYPE (ar))) != FUNCTION_TYPE);
1836
1837       return build_indirect_ref (build_binary_op (PLUS_EXPR, ar, index, 0),
1838                                  "array indexing");
1839     }
1840 }
1841 \f
1842 /* Build an external reference to identifier ID.  FUN indicates
1843    whether this will be used for a function call.  LOC is the source
1844    location of the identifier.  */
1845 tree
1846 build_external_ref (tree id, int fun, location_t loc)
1847 {
1848   tree ref;
1849   tree decl = lookup_name (id);
1850
1851   /* In Objective-C, an instance variable (ivar) may be preferred to
1852      whatever lookup_name() found.  */
1853   decl = objc_lookup_ivar (decl, id);
1854
1855   if (decl && decl != error_mark_node)
1856     ref = decl;
1857   else if (fun)
1858     /* Implicit function declaration.  */
1859     ref = implicitly_declare (id);
1860   else if (decl == error_mark_node)
1861     /* Don't complain about something that's already been
1862        complained about.  */
1863     return error_mark_node;
1864   else
1865     {
1866       undeclared_variable (id, loc);
1867       return error_mark_node;
1868     }
1869
1870   if (TREE_TYPE (ref) == error_mark_node)
1871     return error_mark_node;
1872
1873   if (TREE_DEPRECATED (ref))
1874     warn_deprecated_use (ref);
1875
1876   if (!skip_evaluation)
1877     assemble_external (ref);
1878   TREE_USED (ref) = 1;
1879
1880   if (TREE_CODE (ref) == FUNCTION_DECL && !in_alignof)
1881     {
1882       if (!in_sizeof && !in_typeof)
1883         C_DECL_USED (ref) = 1;
1884       else if (DECL_INITIAL (ref) == 0
1885                && DECL_EXTERNAL (ref)
1886                && !TREE_PUBLIC (ref))
1887         record_maybe_used_decl (ref);
1888     }
1889
1890   if (TREE_CODE (ref) == CONST_DECL)
1891     {
1892       ref = DECL_INITIAL (ref);
1893       TREE_CONSTANT (ref) = 1;
1894       TREE_INVARIANT (ref) = 1;
1895     }
1896   else if (current_function_decl != 0
1897            && !DECL_FILE_SCOPE_P (current_function_decl)
1898            && (TREE_CODE (ref) == VAR_DECL
1899                || TREE_CODE (ref) == PARM_DECL
1900                || TREE_CODE (ref) == FUNCTION_DECL))
1901     {
1902       tree context = decl_function_context (ref);
1903
1904       if (context != 0 && context != current_function_decl)
1905         DECL_NONLOCAL (ref) = 1;
1906     }
1907
1908   return ref;
1909 }
1910
1911 /* Record details of decls possibly used inside sizeof or typeof.  */
1912 struct maybe_used_decl
1913 {
1914   /* The decl.  */
1915   tree decl;
1916   /* The level seen at (in_sizeof + in_typeof).  */
1917   int level;
1918   /* The next one at this level or above, or NULL.  */
1919   struct maybe_used_decl *next;
1920 };
1921
1922 static struct maybe_used_decl *maybe_used_decls;
1923
1924 /* Record that DECL, an undefined static function reference seen
1925    inside sizeof or typeof, might be used if the operand of sizeof is
1926    a VLA type or the operand of typeof is a variably modified
1927    type.  */
1928
1929 static void
1930 record_maybe_used_decl (tree decl)
1931 {
1932   struct maybe_used_decl *t = XOBNEW (&parser_obstack, struct maybe_used_decl);
1933   t->decl = decl;
1934   t->level = in_sizeof + in_typeof;
1935   t->next = maybe_used_decls;
1936   maybe_used_decls = t;
1937 }
1938
1939 /* Pop the stack of decls possibly used inside sizeof or typeof.  If
1940    USED is false, just discard them.  If it is true, mark them used
1941    (if no longer inside sizeof or typeof) or move them to the next
1942    level up (if still inside sizeof or typeof).  */
1943
1944 void
1945 pop_maybe_used (bool used)
1946 {
1947   struct maybe_used_decl *p = maybe_used_decls;
1948   int cur_level = in_sizeof + in_typeof;
1949   while (p && p->level > cur_level)
1950     {
1951       if (used)
1952         {
1953           if (cur_level == 0)
1954             C_DECL_USED (p->decl) = 1;
1955           else
1956             p->level = cur_level;
1957         }
1958       p = p->next;
1959     }
1960   if (!used || cur_level == 0)
1961     maybe_used_decls = p;
1962 }
1963
1964 /* Return the result of sizeof applied to EXPR.  */
1965
1966 struct c_expr
1967 c_expr_sizeof_expr (struct c_expr expr)
1968 {
1969   struct c_expr ret;
1970   if (expr.value == error_mark_node)
1971     {
1972       ret.value = error_mark_node;
1973       ret.original_code = ERROR_MARK;
1974       pop_maybe_used (false);
1975     }
1976   else
1977     {
1978       ret.value = c_sizeof (TREE_TYPE (expr.value));
1979       ret.original_code = ERROR_MARK;
1980       pop_maybe_used (C_TYPE_VARIABLE_SIZE (TREE_TYPE (expr.value)));
1981     }
1982   return ret;
1983 }
1984
1985 /* Return the result of sizeof applied to T, a structure for the type
1986    name passed to sizeof (rather than the type itself).  */
1987
1988 struct c_expr
1989 c_expr_sizeof_type (struct c_type_name *t)
1990 {
1991   tree type;
1992   struct c_expr ret;
1993   type = groktypename (t);
1994   ret.value = c_sizeof (type);
1995   ret.original_code = ERROR_MARK;
1996   pop_maybe_used (C_TYPE_VARIABLE_SIZE (type));
1997   return ret;
1998 }
1999
2000 /* Build a function call to function FUNCTION with parameters PARAMS.
2001    PARAMS is a list--a chain of TREE_LIST nodes--in which the
2002    TREE_VALUE of each node is a parameter-expression.
2003    FUNCTION's data type may be a function type or a pointer-to-function.  */
2004
2005 tree
2006 build_function_call (tree function, tree params)
2007 {
2008   tree fntype, fundecl = 0;
2009   tree coerced_params;
2010   tree name = NULL_TREE, result;
2011   tree tem;
2012
2013   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
2014   STRIP_TYPE_NOPS (function);
2015
2016   /* Convert anything with function type to a pointer-to-function.  */
2017   if (TREE_CODE (function) == FUNCTION_DECL)
2018     {
2019       /* Implement type-directed function overloading for builtins.
2020          resolve_overloaded_builtin and targetm.resolve_overloaded_builtin
2021          handle all the type checking.  The result is a complete expression
2022          that implements this function call.  */
2023       tem = resolve_overloaded_builtin (function, params);
2024       if (tem)
2025         return tem;
2026
2027       name = DECL_NAME (function);
2028       fundecl = function;
2029     }
2030   if (TREE_CODE (TREE_TYPE (function)) == FUNCTION_TYPE)
2031     function = function_to_pointer_conversion (function);
2032
2033   /* For Objective-C, convert any calls via a cast to OBJC_TYPE_REF
2034      expressions, like those used for ObjC messenger dispatches.  */
2035   function = objc_rewrite_function_call (function, params);
2036
2037   fntype = TREE_TYPE (function);
2038
2039   if (TREE_CODE (fntype) == ERROR_MARK)
2040     return error_mark_node;
2041
2042   if (!(TREE_CODE (fntype) == POINTER_TYPE
2043         && TREE_CODE (TREE_TYPE (fntype)) == FUNCTION_TYPE))
2044     {
2045       error ("called object %qE is not a function", function);
2046       return error_mark_node;
2047     }
2048
2049   if (fundecl && TREE_THIS_VOLATILE (fundecl))
2050     current_function_returns_abnormally = 1;
2051
2052   /* fntype now gets the type of function pointed to.  */
2053   fntype = TREE_TYPE (fntype);
2054
2055   /* Check that the function is called through a compatible prototype.
2056      If it is not, replace the call by a trap, wrapped up in a compound
2057      expression if necessary.  This has the nice side-effect to prevent
2058      the tree-inliner from generating invalid assignment trees which may
2059      blow up in the RTL expander later.  */
2060   if (TREE_CODE (function) == NOP_EXPR
2061       && TREE_CODE (tem = TREE_OPERAND (function, 0)) == ADDR_EXPR
2062       && TREE_CODE (tem = TREE_OPERAND (tem, 0)) == FUNCTION_DECL
2063       && !comptypes (fntype, TREE_TYPE (tem)))
2064     {
2065       tree return_type = TREE_TYPE (fntype);
2066       tree trap = build_function_call (built_in_decls[BUILT_IN_TRAP],
2067                                        NULL_TREE);
2068
2069       /* This situation leads to run-time undefined behavior.  We can't,
2070          therefore, simply error unless we can prove that all possible
2071          executions of the program must execute the code.  */
2072       warning (0, "function called through a non-compatible type");
2073
2074       /* We can, however, treat "undefined" any way we please.
2075          Call abort to encourage the user to fix the program.  */
2076       inform ("if this code is reached, the program will abort");
2077
2078       if (VOID_TYPE_P (return_type))
2079         return trap;
2080       else
2081         {
2082           tree rhs;
2083
2084           if (AGGREGATE_TYPE_P (return_type))
2085             rhs = build_compound_literal (return_type,
2086                                           build_constructor (return_type, 0));
2087           else
2088             rhs = fold_build1 (NOP_EXPR, return_type, integer_zero_node);
2089
2090           return build2 (COMPOUND_EXPR, return_type, trap, rhs);
2091         }
2092     }
2093
2094   /* Convert the parameters to the types declared in the
2095      function prototype, or apply default promotions.  */
2096
2097   coerced_params
2098     = convert_arguments (TYPE_ARG_TYPES (fntype), params, function, fundecl);
2099
2100   if (coerced_params == error_mark_node)
2101     return error_mark_node;
2102
2103   /* Check that the arguments to the function are valid.  */
2104
2105   check_function_arguments (TYPE_ATTRIBUTES (fntype), coerced_params,
2106                             TYPE_ARG_TYPES (fntype));
2107
2108   result = build3 (CALL_EXPR, TREE_TYPE (fntype),
2109                    function, coerced_params, NULL_TREE);
2110   TREE_SIDE_EFFECTS (result) = 1;
2111
2112   if (require_constant_value)
2113     {
2114       result = fold_initializer (result);
2115
2116       if (TREE_CONSTANT (result)
2117           && (name == NULL_TREE
2118               || strncmp (IDENTIFIER_POINTER (name), "__builtin_", 10) != 0))
2119         pedwarn_init ("initializer element is not constant");
2120     }
2121   else
2122     result = fold (result);
2123
2124   if (VOID_TYPE_P (TREE_TYPE (result)))
2125     return result;
2126   return require_complete_type (result);
2127 }
2128 \f
2129 /* Convert the argument expressions in the list VALUES
2130    to the types in the list TYPELIST.  The result is a list of converted
2131    argument expressions, unless there are too few arguments in which
2132    case it is error_mark_node.
2133
2134    If TYPELIST is exhausted, or when an element has NULL as its type,
2135    perform the default conversions.
2136
2137    PARMLIST is the chain of parm decls for the function being called.
2138    It may be 0, if that info is not available.
2139    It is used only for generating error messages.
2140
2141    FUNCTION is a tree for the called function.  It is used only for
2142    error messages, where it is formatted with %qE.
2143
2144    This is also where warnings about wrong number of args are generated.
2145
2146    Both VALUES and the returned value are chains of TREE_LIST nodes
2147    with the elements of the list in the TREE_VALUE slots of those nodes.  */
2148
2149 static tree
2150 convert_arguments (tree typelist, tree values, tree function, tree fundecl)
2151 {
2152   tree typetail, valtail;
2153   tree result = NULL;
2154   int parmnum;
2155   tree selector;
2156
2157   /* Change pointer to function to the function itself for
2158      diagnostics.  */
2159   if (TREE_CODE (function) == ADDR_EXPR
2160       && TREE_CODE (TREE_OPERAND (function, 0)) == FUNCTION_DECL)
2161     function = TREE_OPERAND (function, 0);
2162
2163   /* Handle an ObjC selector specially for diagnostics.  */
2164   selector = objc_message_selector ();
2165
2166   /* Scan the given expressions and types, producing individual
2167      converted arguments and pushing them on RESULT in reverse order.  */
2168
2169   for (valtail = values, typetail = typelist, parmnum = 0;
2170        valtail;
2171        valtail = TREE_CHAIN (valtail), parmnum++)
2172     {
2173       tree type = typetail ? TREE_VALUE (typetail) : 0;
2174       tree val = TREE_VALUE (valtail);
2175       tree rname = function;
2176       int argnum = parmnum + 1;
2177       const char *invalid_func_diag;
2178
2179       if (type == void_type_node)
2180         {
2181           error ("too many arguments to function %qE", function);
2182           break;
2183         }
2184
2185       if (selector && argnum > 2)
2186         {
2187           rname = selector;
2188           argnum -= 2;
2189         }
2190
2191       STRIP_TYPE_NOPS (val);
2192
2193       val = require_complete_type (val);
2194
2195       if (type != 0)
2196         {
2197           /* Formal parm type is specified by a function prototype.  */
2198           tree parmval;
2199
2200           if (type == error_mark_node || !COMPLETE_TYPE_P (type))
2201             {
2202               error ("type of formal parameter %d is incomplete", parmnum + 1);
2203               parmval = val;
2204             }
2205           else
2206             {
2207               /* Optionally warn about conversions that
2208                  differ from the default conversions.  */
2209               if (warn_conversion || warn_traditional)
2210                 {
2211                   unsigned int formal_prec = TYPE_PRECISION (type);
2212
2213                   if (INTEGRAL_TYPE_P (type)
2214                       && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
2215                     warning (0, "passing argument %d of %qE as integer "
2216                              "rather than floating due to prototype",
2217                              argnum, rname);
2218                   if (INTEGRAL_TYPE_P (type)
2219                       && TREE_CODE (TREE_TYPE (val)) == COMPLEX_TYPE)
2220                     warning (0, "passing argument %d of %qE as integer "
2221                              "rather than complex due to prototype",
2222                              argnum, rname);
2223                   else if (TREE_CODE (type) == COMPLEX_TYPE
2224                            && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
2225                     warning (0, "passing argument %d of %qE as complex "
2226                              "rather than floating due to prototype",
2227                              argnum, rname);
2228                   else if (TREE_CODE (type) == REAL_TYPE
2229                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2230                     warning (0, "passing argument %d of %qE as floating "
2231                              "rather than integer due to prototype",
2232                              argnum, rname);
2233                   else if (TREE_CODE (type) == COMPLEX_TYPE
2234                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2235                     warning (0, "passing argument %d of %qE as complex "
2236                              "rather than integer due to prototype",
2237                              argnum, rname);
2238                   else if (TREE_CODE (type) == REAL_TYPE
2239                            && TREE_CODE (TREE_TYPE (val)) == COMPLEX_TYPE)
2240                     warning (0, "passing argument %d of %qE as floating "
2241                              "rather than complex due to prototype",
2242                              argnum, rname);
2243                   /* ??? At some point, messages should be written about
2244                      conversions between complex types, but that's too messy
2245                      to do now.  */
2246                   else if (TREE_CODE (type) == REAL_TYPE
2247                            && TREE_CODE (TREE_TYPE (val)) == REAL_TYPE)
2248                     {
2249                       /* Warn if any argument is passed as `float',
2250                          since without a prototype it would be `double'.  */
2251                       if (formal_prec == TYPE_PRECISION (float_type_node))
2252                         warning (0, "passing argument %d of %qE as %<float%> "
2253                                  "rather than %<double%> due to prototype",
2254                                  argnum, rname);
2255                     }
2256                   /* Detect integer changing in width or signedness.
2257                      These warnings are only activated with
2258                      -Wconversion, not with -Wtraditional.  */
2259                   else if (warn_conversion && INTEGRAL_TYPE_P (type)
2260                            && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2261                     {
2262                       tree would_have_been = default_conversion (val);
2263                       tree type1 = TREE_TYPE (would_have_been);
2264
2265                       if (TREE_CODE (type) == ENUMERAL_TYPE
2266                           && (TYPE_MAIN_VARIANT (type)
2267                               == TYPE_MAIN_VARIANT (TREE_TYPE (val))))
2268                         /* No warning if function asks for enum
2269                            and the actual arg is that enum type.  */
2270                         ;
2271                       else if (formal_prec != TYPE_PRECISION (type1))
2272                         warning (OPT_Wconversion, "passing argument %d of %qE "
2273                                  "with different width due to prototype",
2274                                  argnum, rname);
2275                       else if (TYPE_UNSIGNED (type) == TYPE_UNSIGNED (type1))
2276                         ;
2277                       /* Don't complain if the formal parameter type
2278                          is an enum, because we can't tell now whether
2279                          the value was an enum--even the same enum.  */
2280                       else if (TREE_CODE (type) == ENUMERAL_TYPE)
2281                         ;
2282                       else if (TREE_CODE (val) == INTEGER_CST
2283                                && int_fits_type_p (val, type))
2284                         /* Change in signedness doesn't matter
2285                            if a constant value is unaffected.  */
2286                         ;
2287                       /* If the value is extended from a narrower
2288                          unsigned type, it doesn't matter whether we
2289                          pass it as signed or unsigned; the value
2290                          certainly is the same either way.  */
2291                       else if (TYPE_PRECISION (TREE_TYPE (val)) < TYPE_PRECISION (type)
2292                                && TYPE_UNSIGNED (TREE_TYPE (val)))
2293                         ;
2294                       else if (TYPE_UNSIGNED (type))
2295                         warning (OPT_Wconversion, "passing argument %d of %qE "
2296                                  "as unsigned due to prototype",
2297                                  argnum, rname);
2298                       else
2299                         warning (OPT_Wconversion, "passing argument %d of %qE "
2300                                  "as signed due to prototype", argnum, rname);
2301                     }
2302                 }
2303
2304               parmval = convert_for_assignment (type, val, ic_argpass,
2305                                                 fundecl, function,
2306                                                 parmnum + 1);
2307
2308               if (targetm.calls.promote_prototypes (fundecl ? TREE_TYPE (fundecl) : 0)
2309                   && INTEGRAL_TYPE_P (type)
2310                   && (TYPE_PRECISION (type) < TYPE_PRECISION (integer_type_node)))
2311                 parmval = default_conversion (parmval);
2312             }
2313           result = tree_cons (NULL_TREE, parmval, result);
2314         }
2315       else if (TREE_CODE (TREE_TYPE (val)) == REAL_TYPE
2316                && (TYPE_PRECISION (TREE_TYPE (val))
2317                    < TYPE_PRECISION (double_type_node)))
2318         /* Convert `float' to `double'.  */
2319         result = tree_cons (NULL_TREE, convert (double_type_node, val), result);
2320       else if ((invalid_func_diag =
2321                 targetm.calls.invalid_arg_for_unprototyped_fn (typelist, fundecl, val)))
2322         {
2323           error (invalid_func_diag);
2324           return error_mark_node;
2325         }
2326       else
2327         /* Convert `short' and `char' to full-size `int'.  */
2328         result = tree_cons (NULL_TREE, default_conversion (val), result);
2329
2330       if (typetail)
2331         typetail = TREE_CHAIN (typetail);
2332     }
2333
2334   if (typetail != 0 && TREE_VALUE (typetail) != void_type_node)
2335     {
2336       error ("too few arguments to function %qE", function);
2337       return error_mark_node;
2338     }
2339
2340   return nreverse (result);
2341 }
2342 \f
2343 /* This is the entry point used by the parser to build unary operators
2344    in the input.  CODE, a tree_code, specifies the unary operator, and
2345    ARG is the operand.  For unary plus, the C parser currently uses
2346    CONVERT_EXPR for code.  */
2347
2348 struct c_expr
2349 parser_build_unary_op (enum tree_code code, struct c_expr arg)
2350 {
2351   struct c_expr result;
2352
2353   result.original_code = ERROR_MARK;
2354   result.value = build_unary_op (code, arg.value, 0);
2355   overflow_warning (result.value);
2356   return result;
2357 }
2358
2359 /* This is the entry point used by the parser to build binary operators
2360    in the input.  CODE, a tree_code, specifies the binary operator, and
2361    ARG1 and ARG2 are the operands.  In addition to constructing the
2362    expression, we check for operands that were written with other binary
2363    operators in a way that is likely to confuse the user.  */
2364
2365 struct c_expr
2366 parser_build_binary_op (enum tree_code code, struct c_expr arg1,
2367                         struct c_expr arg2)
2368 {
2369   struct c_expr result;
2370
2371   enum tree_code code1 = arg1.original_code;
2372   enum tree_code code2 = arg2.original_code;
2373
2374   result.value = build_binary_op (code, arg1.value, arg2.value, 1);
2375   result.original_code = code;
2376
2377   if (TREE_CODE (result.value) == ERROR_MARK)
2378     return result;
2379
2380   /* Check for cases such as x+y<<z which users are likely
2381      to misinterpret.  */
2382   if (warn_parentheses)
2383     {
2384       if (code == LSHIFT_EXPR || code == RSHIFT_EXPR)
2385         {
2386           if (code1 == PLUS_EXPR || code1 == MINUS_EXPR
2387               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2388             warning (OPT_Wparentheses,
2389                      "suggest parentheses around + or - inside shift");
2390         }
2391
2392       if (code == TRUTH_ORIF_EXPR)
2393         {
2394           if (code1 == TRUTH_ANDIF_EXPR
2395               || code2 == TRUTH_ANDIF_EXPR)
2396             warning (OPT_Wparentheses,
2397                      "suggest parentheses around && within ||");
2398         }
2399
2400       if (code == BIT_IOR_EXPR)
2401         {
2402           if (code1 == BIT_AND_EXPR || code1 == BIT_XOR_EXPR
2403               || code1 == PLUS_EXPR || code1 == MINUS_EXPR
2404               || code2 == BIT_AND_EXPR || code2 == BIT_XOR_EXPR
2405               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2406             warning (OPT_Wparentheses,
2407                      "suggest parentheses around arithmetic in operand of |");
2408           /* Check cases like x|y==z */
2409           if (TREE_CODE_CLASS (code1) == tcc_comparison
2410               || TREE_CODE_CLASS (code2) == tcc_comparison)
2411             warning (OPT_Wparentheses,
2412                      "suggest parentheses around comparison in operand of |");
2413         }
2414
2415       if (code == BIT_XOR_EXPR)
2416         {
2417           if (code1 == BIT_AND_EXPR
2418               || code1 == PLUS_EXPR || code1 == MINUS_EXPR
2419               || code2 == BIT_AND_EXPR
2420               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2421             warning (OPT_Wparentheses,
2422                      "suggest parentheses around arithmetic in operand of ^");
2423           /* Check cases like x^y==z */
2424           if (TREE_CODE_CLASS (code1) == tcc_comparison
2425               || TREE_CODE_CLASS (code2) == tcc_comparison)
2426             warning (OPT_Wparentheses,
2427                      "suggest parentheses around comparison in operand of ^");
2428         }
2429
2430       if (code == BIT_AND_EXPR)
2431         {
2432           if (code1 == PLUS_EXPR || code1 == MINUS_EXPR
2433               || code2 == PLUS_EXPR || code2 == MINUS_EXPR)
2434             warning (OPT_Wparentheses,
2435                      "suggest parentheses around + or - in operand of &");
2436           /* Check cases like x&y==z */
2437           if (TREE_CODE_CLASS (code1) == tcc_comparison
2438               || TREE_CODE_CLASS (code2) == tcc_comparison)
2439             warning (OPT_Wparentheses,
2440                      "suggest parentheses around comparison in operand of &");
2441         }
2442       /* Similarly, check for cases like 1<=i<=10 that are probably errors.  */
2443       if (TREE_CODE_CLASS (code) == tcc_comparison
2444           && (TREE_CODE_CLASS (code1) == tcc_comparison
2445               || TREE_CODE_CLASS (code2) == tcc_comparison))
2446         warning (OPT_Wparentheses, "comparisons like X<=Y<=Z do not "
2447                  "have their mathematical meaning");
2448
2449     }
2450
2451   unsigned_conversion_warning (result.value, arg1.value);
2452   unsigned_conversion_warning (result.value, arg2.value);
2453   overflow_warning (result.value);
2454
2455   return result;
2456 }
2457 \f
2458 /* Return a tree for the difference of pointers OP0 and OP1.
2459    The resulting tree has type int.  */
2460
2461 static tree
2462 pointer_diff (tree op0, tree op1)
2463 {
2464   tree restype = ptrdiff_type_node;
2465
2466   tree target_type = TREE_TYPE (TREE_TYPE (op0));
2467   tree con0, con1, lit0, lit1;
2468   tree orig_op1 = op1;
2469
2470   if (pedantic || warn_pointer_arith)
2471     {
2472       if (TREE_CODE (target_type) == VOID_TYPE)
2473         pedwarn ("pointer of type %<void *%> used in subtraction");
2474       if (TREE_CODE (target_type) == FUNCTION_TYPE)
2475         pedwarn ("pointer to a function used in subtraction");
2476     }
2477
2478   /* If the conversion to ptrdiff_type does anything like widening or
2479      converting a partial to an integral mode, we get a convert_expression
2480      that is in the way to do any simplifications.
2481      (fold-const.c doesn't know that the extra bits won't be needed.
2482      split_tree uses STRIP_SIGN_NOPS, which leaves conversions to a
2483      different mode in place.)
2484      So first try to find a common term here 'by hand'; we want to cover
2485      at least the cases that occur in legal static initializers.  */
2486   con0 = TREE_CODE (op0) == NOP_EXPR ? TREE_OPERAND (op0, 0) : op0;
2487   con1 = TREE_CODE (op1) == NOP_EXPR ? TREE_OPERAND (op1, 0) : op1;
2488
2489   if (TREE_CODE (con0) == PLUS_EXPR)
2490     {
2491       lit0 = TREE_OPERAND (con0, 1);
2492       con0 = TREE_OPERAND (con0, 0);
2493     }
2494   else
2495     lit0 = integer_zero_node;
2496
2497   if (TREE_CODE (con1) == PLUS_EXPR)
2498     {
2499       lit1 = TREE_OPERAND (con1, 1);
2500       con1 = TREE_OPERAND (con1, 0);
2501     }
2502   else
2503     lit1 = integer_zero_node;
2504
2505   if (operand_equal_p (con0, con1, 0))
2506     {
2507       op0 = lit0;
2508       op1 = lit1;
2509     }
2510
2511
2512   /* First do the subtraction as integers;
2513      then drop through to build the divide operator.
2514      Do not do default conversions on the minus operator
2515      in case restype is a short type.  */
2516
2517   op0 = build_binary_op (MINUS_EXPR, convert (restype, op0),
2518                          convert (restype, op1), 0);
2519   /* This generates an error if op1 is pointer to incomplete type.  */
2520   if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (TREE_TYPE (orig_op1))))
2521     error ("arithmetic on pointer to an incomplete type");
2522
2523   /* This generates an error if op0 is pointer to incomplete type.  */
2524   op1 = c_size_in_bytes (target_type);
2525
2526   /* Divide by the size, in easiest possible way.  */
2527   return fold_build2 (EXACT_DIV_EXPR, restype, op0, convert (restype, op1));
2528 }
2529 \f
2530 /* Construct and perhaps optimize a tree representation
2531    for a unary operation.  CODE, a tree_code, specifies the operation
2532    and XARG is the operand.
2533    For any CODE other than ADDR_EXPR, FLAG nonzero suppresses
2534    the default promotions (such as from short to int).
2535    For ADDR_EXPR, the default promotions are not applied; FLAG nonzero
2536    allows non-lvalues; this is only used to handle conversion of non-lvalue
2537    arrays to pointers in C99.  */
2538
2539 tree
2540 build_unary_op (enum tree_code code, tree xarg, int flag)
2541 {
2542   /* No default_conversion here.  It causes trouble for ADDR_EXPR.  */
2543   tree arg = xarg;
2544   tree argtype = 0;
2545   enum tree_code typecode = TREE_CODE (TREE_TYPE (arg));
2546   tree val;
2547   int noconvert = flag;
2548   const char *invalid_op_diag;
2549
2550   if (typecode == ERROR_MARK)
2551     return error_mark_node;
2552   if (typecode == ENUMERAL_TYPE || typecode == BOOLEAN_TYPE)
2553     typecode = INTEGER_TYPE;
2554
2555   if ((invalid_op_diag
2556        = targetm.invalid_unary_op (code, TREE_TYPE (xarg))))
2557     {
2558       error (invalid_op_diag);
2559       return error_mark_node;
2560     }
2561
2562   switch (code)
2563     {
2564     case CONVERT_EXPR:
2565       /* This is used for unary plus, because a CONVERT_EXPR
2566          is enough to prevent anybody from looking inside for
2567          associativity, but won't generate any code.  */
2568       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2569             || typecode == COMPLEX_TYPE
2570             || typecode == VECTOR_TYPE))
2571         {
2572           error ("wrong type argument to unary plus");
2573           return error_mark_node;
2574         }
2575       else if (!noconvert)
2576         arg = default_conversion (arg);
2577       arg = non_lvalue (arg);
2578       break;
2579
2580     case NEGATE_EXPR:
2581       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2582             || typecode == COMPLEX_TYPE
2583             || typecode == VECTOR_TYPE))
2584         {
2585           error ("wrong type argument to unary minus");
2586           return error_mark_node;
2587         }
2588       else if (!noconvert)
2589         arg = default_conversion (arg);
2590       break;
2591
2592     case BIT_NOT_EXPR:
2593       if (typecode == INTEGER_TYPE || typecode == VECTOR_TYPE)
2594         {
2595           if (!noconvert)
2596             arg = default_conversion (arg);
2597         }
2598       else if (typecode == COMPLEX_TYPE)
2599         {
2600           code = CONJ_EXPR;
2601           if (pedantic)
2602             pedwarn ("ISO C does not support %<~%> for complex conjugation");
2603           if (!noconvert)
2604             arg = default_conversion (arg);
2605         }
2606       else
2607         {
2608           error ("wrong type argument to bit-complement");
2609           return error_mark_node;
2610         }
2611       break;
2612
2613     case ABS_EXPR:
2614       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE))
2615         {
2616           error ("wrong type argument to abs");
2617           return error_mark_node;
2618         }
2619       else if (!noconvert)
2620         arg = default_conversion (arg);
2621       break;
2622
2623     case CONJ_EXPR:
2624       /* Conjugating a real value is a no-op, but allow it anyway.  */
2625       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
2626             || typecode == COMPLEX_TYPE))
2627         {
2628           error ("wrong type argument to conjugation");
2629           return error_mark_node;
2630         }
2631       else if (!noconvert)
2632         arg = default_conversion (arg);
2633       break;
2634
2635     case TRUTH_NOT_EXPR:
2636       if (typecode != INTEGER_TYPE
2637           && typecode != REAL_TYPE && typecode != POINTER_TYPE
2638           && typecode != COMPLEX_TYPE)
2639         {
2640           error ("wrong type argument to unary exclamation mark");
2641           return error_mark_node;
2642         }
2643       arg = c_objc_common_truthvalue_conversion (arg);
2644       return invert_truthvalue (arg);
2645
2646     case NOP_EXPR:
2647       break;
2648
2649     case REALPART_EXPR:
2650       if (TREE_CODE (arg) == COMPLEX_CST)
2651         return TREE_REALPART (arg);
2652       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
2653         return fold_build1 (REALPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg);
2654       else
2655         return arg;
2656
2657     case IMAGPART_EXPR:
2658       if (TREE_CODE (arg) == COMPLEX_CST)
2659         return TREE_IMAGPART (arg);
2660       else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
2661         return fold_build1 (IMAGPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg);
2662       else
2663         return convert (TREE_TYPE (arg), integer_zero_node);
2664
2665     case PREINCREMENT_EXPR:
2666     case POSTINCREMENT_EXPR:
2667     case PREDECREMENT_EXPR:
2668     case POSTDECREMENT_EXPR:
2669
2670       /* Increment or decrement the real part of the value,
2671          and don't change the imaginary part.  */
2672       if (typecode == COMPLEX_TYPE)
2673         {
2674           tree real, imag;
2675
2676           if (pedantic)
2677             pedwarn ("ISO C does not support %<++%> and %<--%>"
2678                      " on complex types");
2679
2680           arg = stabilize_reference (arg);
2681           real = build_unary_op (REALPART_EXPR, arg, 1);
2682           imag = build_unary_op (IMAGPART_EXPR, arg, 1);
2683           return build2 (COMPLEX_EXPR, TREE_TYPE (arg),
2684                          build_unary_op (code, real, 1), imag);
2685         }
2686
2687       /* Report invalid types.  */
2688
2689       if (typecode != POINTER_TYPE
2690           && typecode != INTEGER_TYPE && typecode != REAL_TYPE)
2691         {
2692           if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
2693             error ("wrong type argument to increment");
2694           else
2695             error ("wrong type argument to decrement");
2696
2697           return error_mark_node;
2698         }
2699
2700       {
2701         tree inc;
2702         tree result_type = TREE_TYPE (arg);
2703
2704         arg = get_unwidened (arg, 0);
2705         argtype = TREE_TYPE (arg);
2706
2707         /* Compute the increment.  */
2708
2709         if (typecode == POINTER_TYPE)
2710           {
2711             /* If pointer target is an undefined struct,
2712                we just cannot know how to do the arithmetic.  */
2713             if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (result_type)))
2714               {
2715                 if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
2716                   error ("increment of pointer to unknown structure");
2717                 else
2718                   error ("decrement of pointer to unknown structure");
2719               }
2720             else if ((pedantic || warn_pointer_arith)
2721                      && (TREE_CODE (TREE_TYPE (result_type)) == FUNCTION_TYPE
2722                          || TREE_CODE (TREE_TYPE (result_type)) == VOID_TYPE))
2723               {
2724                 if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
2725                   pedwarn ("wrong type argument to increment");
2726                 else
2727                   pedwarn ("wrong type argument to decrement");
2728               }
2729
2730             inc = c_size_in_bytes (TREE_TYPE (result_type));
2731           }
2732         else
2733           inc = integer_one_node;
2734
2735         inc = convert (argtype, inc);
2736
2737         /* Complain about anything else that is not a true lvalue.  */
2738         if (!lvalue_or_else (arg, ((code == PREINCREMENT_EXPR
2739                                     || code == POSTINCREMENT_EXPR)
2740                                    ? lv_increment
2741                                    : lv_decrement)))
2742           return error_mark_node;
2743
2744         /* Report a read-only lvalue.  */
2745         if (TREE_READONLY (arg))
2746           readonly_error (arg,
2747                           ((code == PREINCREMENT_EXPR
2748                             || code == POSTINCREMENT_EXPR)
2749                            ? lv_increment : lv_decrement));
2750
2751         if (TREE_CODE (TREE_TYPE (arg)) == BOOLEAN_TYPE)
2752           val = boolean_increment (code, arg);
2753         else
2754           val = build2 (code, TREE_TYPE (arg), arg, inc);
2755         TREE_SIDE_EFFECTS (val) = 1;
2756         val = convert (result_type, val);
2757         if (TREE_CODE (val) != code)
2758           TREE_NO_WARNING (val) = 1;
2759         return val;
2760       }
2761
2762     case ADDR_EXPR:
2763       /* Note that this operation never does default_conversion.  */
2764
2765       /* Let &* cancel out to simplify resulting code.  */
2766       if (TREE_CODE (arg) == INDIRECT_REF)
2767         {
2768           /* Don't let this be an lvalue.  */
2769           if (lvalue_p (TREE_OPERAND (arg, 0)))
2770             return non_lvalue (TREE_OPERAND (arg, 0));
2771           return TREE_OPERAND (arg, 0);
2772         }
2773
2774       /* For &x[y], return x+y */
2775       if (TREE_CODE (arg) == ARRAY_REF)
2776         {
2777           tree op0 = TREE_OPERAND (arg, 0);
2778           if (!c_mark_addressable (op0))
2779             return error_mark_node;
2780           return build_binary_op (PLUS_EXPR,
2781                                   (TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE
2782                                    ? array_to_pointer_conversion (op0)
2783                                    : op0),
2784                                   TREE_OPERAND (arg, 1), 1);
2785         }
2786
2787       /* Anything not already handled and not a true memory reference
2788          or a non-lvalue array is an error.  */
2789       else if (typecode != FUNCTION_TYPE && !flag
2790                && !lvalue_or_else (arg, lv_addressof))
2791         return error_mark_node;
2792
2793       /* Ordinary case; arg is a COMPONENT_REF or a decl.  */
2794       argtype = TREE_TYPE (arg);
2795
2796       /* If the lvalue is const or volatile, merge that into the type
2797          to which the address will point.  Note that you can't get a
2798          restricted pointer by taking the address of something, so we
2799          only have to deal with `const' and `volatile' here.  */
2800       if ((DECL_P (arg) || REFERENCE_CLASS_P (arg))
2801           && (TREE_READONLY (arg) || TREE_THIS_VOLATILE (arg)))
2802           argtype = c_build_type_variant (argtype,
2803                                           TREE_READONLY (arg),
2804                                           TREE_THIS_VOLATILE (arg));
2805
2806       if (!c_mark_addressable (arg))
2807         return error_mark_node;
2808
2809       gcc_assert (TREE_CODE (arg) != COMPONENT_REF
2810                   || !DECL_C_BIT_FIELD (TREE_OPERAND (arg, 1)));
2811
2812       argtype = build_pointer_type (argtype);
2813
2814       /* ??? Cope with user tricks that amount to offsetof.  Delete this
2815          when we have proper support for integer constant expressions.  */
2816       val = get_base_address (arg);
2817       if (val && TREE_CODE (val) == INDIRECT_REF
2818           && integer_zerop (TREE_OPERAND (val, 0)))
2819         return fold_convert (argtype, fold_offsetof (arg));
2820
2821       val = build1 (ADDR_EXPR, argtype, arg);
2822
2823       return val;
2824
2825     default:
2826       break;
2827     }
2828
2829   if (argtype == 0)
2830     argtype = TREE_TYPE (arg);
2831   val = build1 (code, argtype, arg);
2832   return require_constant_value ? fold_initializer (val) : fold (val);
2833 }
2834
2835 /* Return nonzero if REF is an lvalue valid for this language.
2836    Lvalues can be assigned, unless their type has TYPE_READONLY.
2837    Lvalues can have their address taken, unless they have C_DECL_REGISTER.  */
2838
2839 static int
2840 lvalue_p (tree ref)
2841 {
2842   enum tree_code code = TREE_CODE (ref);
2843
2844   switch (code)
2845     {
2846     case REALPART_EXPR:
2847     case IMAGPART_EXPR:
2848     case COMPONENT_REF:
2849       return lvalue_p (TREE_OPERAND (ref, 0));
2850
2851     case COMPOUND_LITERAL_EXPR:
2852     case STRING_CST:
2853       return 1;
2854
2855     case INDIRECT_REF:
2856     case ARRAY_REF:
2857     case VAR_DECL:
2858     case PARM_DECL:
2859     case RESULT_DECL:
2860     case ERROR_MARK:
2861       return (TREE_CODE (TREE_TYPE (ref)) != FUNCTION_TYPE
2862               && TREE_CODE (TREE_TYPE (ref)) != METHOD_TYPE);
2863
2864     case BIND_EXPR:
2865       return TREE_CODE (TREE_TYPE (ref)) == ARRAY_TYPE;
2866
2867     default:
2868       return 0;
2869     }
2870 }
2871 \f
2872 /* Give an error for storing in something that is 'const'.  */
2873
2874 static void
2875 readonly_error (tree arg, enum lvalue_use use)
2876 {
2877   gcc_assert (use == lv_assign || use == lv_increment || use == lv_decrement);
2878   /* Using this macro rather than (for example) arrays of messages
2879      ensures that all the format strings are checked at compile
2880      time.  */
2881 #define READONLY_MSG(A, I, D) (use == lv_assign                         \
2882                                ? (A)                                    \
2883                                : (use == lv_increment ? (I) : (D)))
2884   if (TREE_CODE (arg) == COMPONENT_REF)
2885     {
2886       if (TYPE_READONLY (TREE_TYPE (TREE_OPERAND (arg, 0))))
2887         readonly_error (TREE_OPERAND (arg, 0), use);
2888       else
2889         error (READONLY_MSG (G_("assignment of read-only member %qD"),
2890                              G_("increment of read-only member %qD"),
2891                              G_("decrement of read-only member %qD")),
2892                TREE_OPERAND (arg, 1));
2893     }
2894   else if (TREE_CODE (arg) == VAR_DECL)
2895     error (READONLY_MSG (G_("assignment of read-only variable %qD"),
2896                          G_("increment of read-only variable %qD"),
2897                          G_("decrement of read-only variable %qD")),
2898            arg);
2899   else
2900     error (READONLY_MSG (G_("assignment of read-only location"),
2901                          G_("increment of read-only location"),
2902                          G_("decrement of read-only location")));
2903 }
2904
2905
2906 /* Return nonzero if REF is an lvalue valid for this language;
2907    otherwise, print an error message and return zero.  USE says
2908    how the lvalue is being used and so selects the error message.  */
2909
2910 static int
2911 lvalue_or_else (tree ref, enum lvalue_use use)
2912 {
2913   int win = lvalue_p (ref);
2914
2915   if (!win)
2916     lvalue_error (use);
2917
2918   return win;
2919 }
2920 \f
2921 /* Mark EXP saying that we need to be able to take the
2922    address of it; it should not be allocated in a register.
2923    Returns true if successful.  */
2924
2925 bool
2926 c_mark_addressable (tree exp)
2927 {
2928   tree x = exp;
2929
2930   while (1)
2931     switch (TREE_CODE (x))
2932       {
2933       case COMPONENT_REF:
2934         if (DECL_C_BIT_FIELD (TREE_OPERAND (x, 1)))
2935           {
2936             error
2937               ("cannot take address of bit-field %qD", TREE_OPERAND (x, 1));
2938             return false;
2939           }
2940
2941         /* ... fall through ...  */
2942
2943       case ADDR_EXPR:
2944       case ARRAY_REF:
2945       case REALPART_EXPR:
2946       case IMAGPART_EXPR:
2947         x = TREE_OPERAND (x, 0);
2948         break;
2949
2950       case COMPOUND_LITERAL_EXPR:
2951       case CONSTRUCTOR:
2952         TREE_ADDRESSABLE (x) = 1;
2953         return true;
2954
2955       case VAR_DECL:
2956       case CONST_DECL:
2957       case PARM_DECL:
2958       case RESULT_DECL:
2959         if (C_DECL_REGISTER (x)
2960             && DECL_NONLOCAL (x))
2961           {
2962             if (TREE_PUBLIC (x) || TREE_STATIC (x) || DECL_EXTERNAL (x))
2963               {
2964                 error
2965                   ("global register variable %qD used in nested function", x);
2966                 return false;
2967               }
2968             pedwarn ("register variable %qD used in nested function", x);
2969           }
2970         else if (C_DECL_REGISTER (x))
2971           {
2972             if (TREE_PUBLIC (x) || TREE_STATIC (x) || DECL_EXTERNAL (x))
2973               error ("address of global register variable %qD requested", x);
2974             else
2975               error ("address of register variable %qD requested", x);
2976             return false;
2977           }
2978
2979         /* drops in */
2980       case FUNCTION_DECL:
2981         TREE_ADDRESSABLE (x) = 1;
2982         /* drops out */
2983       default:
2984         return true;
2985     }
2986 }
2987 \f
2988 /* Build and return a conditional expression IFEXP ? OP1 : OP2.  */
2989
2990 tree
2991 build_conditional_expr (tree ifexp, tree op1, tree op2)
2992 {
2993   tree type1;
2994   tree type2;
2995   enum tree_code code1;
2996   enum tree_code code2;
2997   tree result_type = NULL;
2998   tree orig_op1 = op1, orig_op2 = op2;
2999
3000   /* Promote both alternatives.  */
3001
3002   if (TREE_CODE (TREE_TYPE (op1)) != VOID_TYPE)
3003     op1 = default_conversion (op1);
3004   if (TREE_CODE (TREE_TYPE (op2)) != VOID_TYPE)
3005     op2 = default_conversion (op2);
3006
3007   if (TREE_CODE (ifexp) == ERROR_MARK
3008       || TREE_CODE (TREE_TYPE (op1)) == ERROR_MARK
3009       || TREE_CODE (TREE_TYPE (op2)) == ERROR_MARK)
3010     return error_mark_node;
3011
3012   type1 = TREE_TYPE (op1);
3013   code1 = TREE_CODE (type1);
3014   type2 = TREE_TYPE (op2);
3015   code2 = TREE_CODE (type2);
3016
3017   /* C90 does not permit non-lvalue arrays in conditional expressions.
3018      In C99 they will be pointers by now.  */
3019   if (code1 == ARRAY_TYPE || code2 == ARRAY_TYPE)
3020     {
3021       error ("non-lvalue array in conditional expression");
3022       return error_mark_node;
3023     }
3024
3025   /* Quickly detect the usual case where op1 and op2 have the same type
3026      after promotion.  */
3027   if (TYPE_MAIN_VARIANT (type1) == TYPE_MAIN_VARIANT (type2))
3028     {
3029       if (type1 == type2)
3030         result_type = type1;
3031       else
3032         result_type = TYPE_MAIN_VARIANT (type1);
3033     }
3034   else if ((code1 == INTEGER_TYPE || code1 == REAL_TYPE
3035             || code1 == COMPLEX_TYPE)
3036            && (code2 == INTEGER_TYPE || code2 == REAL_TYPE
3037                || code2 == COMPLEX_TYPE))
3038     {
3039       result_type = c_common_type (type1, type2);
3040
3041       /* If -Wsign-compare, warn here if type1 and type2 have
3042          different signedness.  We'll promote the signed to unsigned
3043          and later code won't know it used to be different.
3044          Do this check on the original types, so that explicit casts
3045          will be considered, but default promotions won't.  */
3046       if (warn_sign_compare && !skip_evaluation)
3047         {
3048           int unsigned_op1 = TYPE_UNSIGNED (TREE_TYPE (orig_op1));
3049           int unsigned_op2 = TYPE_UNSIGNED (TREE_TYPE (orig_op2));
3050
3051           if (unsigned_op1 ^ unsigned_op2)
3052             {
3053               /* Do not warn if the result type is signed, since the
3054                  signed type will only be chosen if it can represent
3055                  all the values of the unsigned type.  */
3056               if (!TYPE_UNSIGNED (result_type))
3057                 /* OK */;
3058               /* Do not warn if the signed quantity is an unsuffixed
3059                  integer literal (or some static constant expression
3060                  involving such literals) and it is non-negative.  */
3061               else if ((unsigned_op2 && tree_expr_nonnegative_p (op1))
3062                        || (unsigned_op1 && tree_expr_nonnegative_p (op2)))
3063                 /* OK */;
3064               else
3065                 warning (0, "signed and unsigned type in conditional expression");
3066             }
3067         }
3068     }
3069   else if (code1 == VOID_TYPE || code2 == VOID_TYPE)
3070     {
3071       if (pedantic && (code1 != VOID_TYPE || code2 != VOID_TYPE))
3072         pedwarn ("ISO C forbids conditional expr with only one void side");
3073       result_type = void_type_node;
3074     }
3075   else if (code1 == POINTER_TYPE && code2 == POINTER_TYPE)
3076     {
3077       if (comp_target_types (type1, type2))
3078         result_type = common_pointer_type (type1, type2);
3079       else if (integer_zerop (op1) && TREE_TYPE (type1) == void_type_node
3080                && TREE_CODE (orig_op1) != NOP_EXPR)
3081         result_type = qualify_type (type2, type1);
3082       else if (integer_zerop (op2) && TREE_TYPE (type2) == void_type_node
3083                && TREE_CODE (orig_op2) != NOP_EXPR)
3084         result_type = qualify_type (type1, type2);
3085       else if (VOID_TYPE_P (TREE_TYPE (type1)))
3086         {
3087           if (pedantic && TREE_CODE (TREE_TYPE (type2)) == FUNCTION_TYPE)
3088             pedwarn ("ISO C forbids conditional expr between "
3089                      "%<void *%> and function pointer");
3090           result_type = build_pointer_type (qualify_type (TREE_TYPE (type1),
3091                                                           TREE_TYPE (type2)));
3092         }
3093       else if (VOID_TYPE_P (TREE_TYPE (type2)))
3094         {
3095           if (pedantic && TREE_CODE (TREE_TYPE (type1)) == FUNCTION_TYPE)
3096             pedwarn ("ISO C forbids conditional expr between "
3097                      "%<void *%> and function pointer");
3098           result_type = build_pointer_type (qualify_type (TREE_TYPE (type2),
3099                                                           TREE_TYPE (type1)));
3100         }
3101       else
3102         {
3103           pedwarn ("pointer type mismatch in conditional expression");
3104           result_type = build_pointer_type (void_type_node);
3105         }
3106     }
3107   else if (code1 == POINTER_TYPE && code2 == INTEGER_TYPE)
3108     {
3109       if (!integer_zerop (op2))
3110         pedwarn ("pointer/integer type mismatch in conditional expression");
3111       else
3112         {
3113           op2 = null_pointer_node;
3114         }
3115       result_type = type1;
3116     }
3117   else if (code2 == POINTER_TYPE && code1 == INTEGER_TYPE)
3118     {
3119       if (!integer_zerop (op1))
3120         pedwarn ("pointer/integer type mismatch in conditional expression");
3121       else
3122         {
3123           op1 = null_pointer_node;
3124         }
3125       result_type = type2;
3126     }
3127
3128   if (!result_type)
3129     {
3130       if (flag_cond_mismatch)
3131         result_type = void_type_node;
3132       else
3133         {
3134           error ("type mismatch in conditional expression");
3135           return error_mark_node;
3136         }
3137     }
3138
3139   /* Merge const and volatile flags of the incoming types.  */
3140   result_type
3141     = build_type_variant (result_type,
3142                           TREE_READONLY (op1) || TREE_READONLY (op2),
3143                           TREE_THIS_VOLATILE (op1) || TREE_THIS_VOLATILE (op2));
3144
3145   if (result_type != TREE_TYPE (op1))
3146     op1 = convert_and_check (result_type, op1);
3147   if (result_type != TREE_TYPE (op2))
3148     op2 = convert_and_check (result_type, op2);
3149
3150   return fold_build3 (COND_EXPR, result_type, ifexp, op1, op2);
3151 }
3152 \f
3153 /* Return a compound expression that performs two expressions and
3154    returns the value of the second of them.  */
3155
3156 tree
3157 build_compound_expr (tree expr1, tree expr2)
3158 {
3159   if (!TREE_SIDE_EFFECTS (expr1))
3160     {
3161       /* The left-hand operand of a comma expression is like an expression
3162          statement: with -Wextra or -Wunused, we should warn if it doesn't have
3163          any side-effects, unless it was explicitly cast to (void).  */
3164       if (warn_unused_value)
3165         {
3166           if (VOID_TYPE_P (TREE_TYPE (expr1))
3167               && TREE_CODE (expr1) == CONVERT_EXPR)
3168             ; /* (void) a, b */
3169           else if (VOID_TYPE_P (TREE_TYPE (expr1))
3170                    && TREE_CODE (expr1) == COMPOUND_EXPR
3171                    && TREE_CODE (TREE_OPERAND (expr1, 1)) == CONVERT_EXPR)
3172             ; /* (void) a, (void) b, c */
3173           else
3174             warning (0, "left-hand operand of comma expression has no effect");
3175         }
3176     }
3177
3178   /* With -Wunused, we should also warn if the left-hand operand does have
3179      side-effects, but computes a value which is not used.  For example, in
3180      `foo() + bar(), baz()' the result of the `+' operator is not used,
3181      so we should issue a warning.  */
3182   else if (warn_unused_value)
3183     warn_if_unused_value (expr1, input_location);
3184
3185   return build2 (COMPOUND_EXPR, TREE_TYPE (expr2), expr1, expr2);
3186 }
3187
3188 /* Build an expression representing a cast to type TYPE of expression EXPR.  */
3189
3190 tree
3191 build_c_cast (tree type, tree expr)
3192 {
3193   tree value = expr;
3194
3195   if (type == error_mark_node || expr == error_mark_node)
3196     return error_mark_node;
3197
3198   /* The ObjC front-end uses TYPE_MAIN_VARIANT to tie together types differing
3199      only in <protocol> qualifications.  But when constructing cast expressions,
3200      the protocols do matter and must be kept around.  */
3201   if (objc_is_object_ptr (type) && objc_is_object_ptr (TREE_TYPE (expr)))
3202     return build1 (NOP_EXPR, type, expr);
3203
3204   type = TYPE_MAIN_VARIANT (type);
3205
3206   if (TREE_CODE (type) == ARRAY_TYPE)
3207     {
3208       error ("cast specifies array type");
3209       return error_mark_node;
3210     }
3211
3212   if (TREE_CODE (type) == FUNCTION_TYPE)
3213     {
3214       error ("cast specifies function type");
3215       return error_mark_node;
3216     }
3217
3218   if (type == TYPE_MAIN_VARIANT (TREE_TYPE (value)))
3219     {
3220       if (pedantic)
3221         {
3222           if (TREE_CODE (type) == RECORD_TYPE
3223               || TREE_CODE (type) == UNION_TYPE)
3224             pedwarn ("ISO C forbids casting nonscalar to the same type");
3225         }
3226     }
3227   else if (TREE_CODE (type) == UNION_TYPE)
3228     {
3229       tree field;
3230
3231       for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
3232         if (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (field)),
3233                        TYPE_MAIN_VARIANT (TREE_TYPE (value))))
3234           break;
3235
3236       if (field)
3237         {
3238           tree t;
3239
3240           if (pedantic)
3241             pedwarn ("ISO C forbids casts to union type");
3242           t = digest_init (type,
3243                            build_constructor_single (type, field, value),
3244                            true, 0);
3245           TREE_CONSTANT (t) = TREE_CONSTANT (value);
3246           TREE_INVARIANT (t) = TREE_INVARIANT (value);
3247           return t;
3248         }
3249       error ("cast to union type from type not present in union");
3250       return error_mark_node;
3251     }
3252   else
3253     {
3254       tree otype, ovalue;
3255
3256       if (type == void_type_node)
3257         return build1 (CONVERT_EXPR, type, value);
3258
3259       otype = TREE_TYPE (value);
3260
3261       /* Optionally warn about potentially worrisome casts.  */
3262
3263       if (warn_cast_qual
3264           && TREE_CODE (type) == POINTER_TYPE
3265           && TREE_CODE (otype) == POINTER_TYPE)
3266         {
3267           tree in_type = type;
3268           tree in_otype = otype;
3269           int added = 0;
3270           int discarded = 0;
3271
3272           /* Check that the qualifiers on IN_TYPE are a superset of
3273              the qualifiers of IN_OTYPE.  The outermost level of
3274              POINTER_TYPE nodes is uninteresting and we stop as soon
3275              as we hit a non-POINTER_TYPE node on either type.  */
3276           do
3277             {
3278               in_otype = TREE_TYPE (in_otype);
3279               in_type = TREE_TYPE (in_type);
3280
3281               /* GNU C allows cv-qualified function types.  'const'
3282                  means the function is very pure, 'volatile' means it
3283                  can't return.  We need to warn when such qualifiers
3284                  are added, not when they're taken away.  */
3285               if (TREE_CODE (in_otype) == FUNCTION_TYPE
3286                   && TREE_CODE (in_type) == FUNCTION_TYPE)
3287                 added |= (TYPE_QUALS (in_type) & ~TYPE_QUALS (in_otype));
3288               else
3289                 discarded |= (TYPE_QUALS (in_otype) & ~TYPE_QUALS (in_type));
3290             }
3291           while (TREE_CODE (in_type) == POINTER_TYPE
3292                  && TREE_CODE (in_otype) == POINTER_TYPE);
3293
3294           if (added)
3295             warning (0, "cast adds new qualifiers to function type");
3296
3297           if (discarded)
3298             /* There are qualifiers present in IN_OTYPE that are not
3299                present in IN_TYPE.  */
3300             warning (0, "cast discards qualifiers from pointer target type");
3301         }
3302
3303       /* Warn about possible alignment problems.  */
3304       if (STRICT_ALIGNMENT
3305           && TREE_CODE (type) == POINTER_TYPE
3306           && TREE_CODE (otype) == POINTER_TYPE
3307           && TREE_CODE (TREE_TYPE (otype)) != VOID_TYPE
3308           && TREE_CODE (TREE_TYPE (otype)) != FUNCTION_TYPE
3309           /* Don't warn about opaque types, where the actual alignment
3310              restriction is unknown.  */
3311           && !((TREE_CODE (TREE_TYPE (otype)) == UNION_TYPE
3312                 || TREE_CODE (TREE_TYPE (otype)) == RECORD_TYPE)
3313                && TYPE_MODE (TREE_TYPE (otype)) == VOIDmode)
3314           && TYPE_ALIGN (TREE_TYPE (type)) > TYPE_ALIGN (TREE_TYPE (otype)))
3315         warning (OPT_Wcast_align,
3316                  "cast increases required alignment of target type");
3317
3318       if (TREE_CODE (type) == INTEGER_TYPE
3319           && TREE_CODE (otype) == POINTER_TYPE
3320           && TYPE_PRECISION (type) != TYPE_PRECISION (otype)
3321           && !TREE_CONSTANT (value))
3322         warning (OPT_Wpointer_to_int_cast,
3323                  "cast from pointer to integer of different size");
3324
3325       if (TREE_CODE (value) == CALL_EXPR
3326           && TREE_CODE (type) != TREE_CODE (otype))
3327         warning (OPT_Wbad_function_cast, "cast from function call of type %qT "
3328                  "to non-matching type %qT", otype, type);
3329
3330       if (TREE_CODE (type) == POINTER_TYPE
3331           && TREE_CODE (otype) == INTEGER_TYPE
3332           && TYPE_PRECISION (type) != TYPE_PRECISION (otype)
3333           /* Don't warn about converting any constant.  */
3334           && !TREE_CONSTANT (value))
3335         warning (OPT_Wint_to_pointer_cast, "cast to pointer from integer "
3336                  "of different size");
3337
3338       if (flag_strict_aliasing && warn_strict_aliasing
3339           && TREE_CODE (type) == POINTER_TYPE
3340           && TREE_CODE (otype) == POINTER_TYPE
3341           && TREE_CODE (expr) == ADDR_EXPR
3342           && (DECL_P (TREE_OPERAND (expr, 0))
3343               || TREE_CODE (TREE_OPERAND (expr, 0)) == COMPONENT_REF)
3344           && !VOID_TYPE_P (TREE_TYPE (type)))
3345         {
3346           /* Casting the address of an object to non void pointer. Warn
3347              if the cast breaks type based aliasing.  */
3348           if (!COMPLETE_TYPE_P (TREE_TYPE (type)))
3349             warning (OPT_Wstrict_aliasing, "type-punning to incomplete type "
3350                      "might break strict-aliasing rules");
3351           else
3352             {
3353               HOST_WIDE_INT set1 = get_alias_set (TREE_TYPE (TREE_OPERAND (expr, 0)));
3354               HOST_WIDE_INT set2 = get_alias_set (TREE_TYPE (type));
3355
3356               if (!alias_sets_conflict_p (set1, set2))
3357                 warning (OPT_Wstrict_aliasing, "dereferencing type-punned "
3358                          "pointer will break strict-aliasing rules");
3359               else if (warn_strict_aliasing > 1
3360                        && !alias_sets_might_conflict_p (set1, set2))
3361                 warning (OPT_Wstrict_aliasing, "dereferencing type-punned "
3362                          "pointer might break strict-aliasing rules");
3363             }
3364         }
3365
3366       /* If pedantic, warn for conversions between function and object
3367          pointer types, except for converting a null pointer constant
3368          to function pointer type.  */
3369       if (pedantic
3370           && TREE_CODE (type) == POINTER_TYPE
3371           && TREE_CODE (otype) == POINTER_TYPE
3372           && TREE_CODE (TREE_TYPE (otype)) == FUNCTION_TYPE
3373           && TREE_CODE (TREE_TYPE (type)) != FUNCTION_TYPE)
3374         pedwarn ("ISO C forbids conversion of function pointer to object pointer type");
3375
3376       if (pedantic
3377           && TREE_CODE (type) == POINTER_TYPE
3378           && TREE_CODE (otype) == POINTER_TYPE
3379           && TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE
3380           && TREE_CODE (TREE_TYPE (otype)) != FUNCTION_TYPE
3381           && !(integer_zerop (value) && TREE_TYPE (otype) == void_type_node
3382                && TREE_CODE (expr) != NOP_EXPR))
3383         pedwarn ("ISO C forbids conversion of object pointer to function pointer type");
3384
3385       ovalue = value;
3386       value = convert (type, value);
3387
3388       /* Ignore any integer overflow caused by the cast.  */
3389       if (TREE_CODE (value) == INTEGER_CST)
3390         {
3391           /* If OVALUE had overflow set, then so will VALUE, so it
3392              is safe to overwrite.  */
3393           if (CONSTANT_CLASS_P (ovalue))
3394             {
3395               TREE_OVERFLOW (value) = TREE_OVERFLOW (ovalue);
3396               /* Similarly, constant_overflow cannot have become cleared.  */
3397               TREE_CONSTANT_OVERFLOW (value) = TREE_CONSTANT_OVERFLOW (ovalue);
3398             }
3399           else
3400             TREE_OVERFLOW (value) = 0;
3401         }
3402     }
3403
3404   /* Don't let a cast be an lvalue.  */
3405   if (value == expr)
3406     value = non_lvalue (value);
3407
3408   return value;
3409 }
3410
3411 /* Interpret a cast of expression EXPR to type TYPE.  */
3412 tree
3413 c_cast_expr (struct c_type_name *type_name, tree expr)
3414 {
3415   tree type;
3416   int saved_wsp = warn_strict_prototypes;
3417
3418   /* This avoids warnings about unprototyped casts on
3419      integers.  E.g. "#define SIG_DFL (void(*)())0".  */
3420   if (TREE_CODE (expr) == INTEGER_CST)
3421     warn_strict_prototypes = 0;
3422   type = groktypename (type_name);
3423   warn_strict_prototypes = saved_wsp;
3424
3425   return build_c_cast (type, expr);
3426 }
3427
3428 \f
3429 /* Build an assignment expression of lvalue LHS from value RHS.
3430    MODIFYCODE is the code for a binary operator that we use
3431    to combine the old value of LHS with RHS to get the new value.
3432    Or else MODIFYCODE is NOP_EXPR meaning do a simple assignment.  */
3433
3434 tree
3435 build_modify_expr (tree lhs, enum tree_code modifycode, tree rhs)
3436 {
3437   tree result;
3438   tree newrhs;
3439   tree lhstype = TREE_TYPE (lhs);
3440   tree olhstype = lhstype;
3441
3442   /* Types that aren't fully specified cannot be used in assignments.  */
3443   lhs = require_complete_type (lhs);
3444
3445   /* Avoid duplicate error messages from operands that had errors.  */
3446   if (TREE_CODE (lhs) == ERROR_MARK || TREE_CODE (rhs) == ERROR_MARK)
3447     return error_mark_node;
3448
3449   STRIP_TYPE_NOPS (rhs);
3450
3451   newrhs = rhs;
3452
3453   /* If a binary op has been requested, combine the old LHS value with the RHS
3454      producing the value we should actually store into the LHS.  */
3455
3456   if (modifycode != NOP_EXPR)
3457     {
3458       lhs = stabilize_reference (lhs);
3459       newrhs = build_binary_op (modifycode, lhs, rhs, 1);
3460     }
3461
3462   if (!lvalue_or_else (lhs, lv_assign))
3463     return error_mark_node;
3464
3465   /* Give an error for storing in something that is 'const'.  */
3466
3467   if (TREE_READONLY (lhs) || TYPE_READONLY (lhstype)
3468       || ((TREE_CODE (lhstype) == RECORD_TYPE
3469            || TREE_CODE (lhstype) == UNION_TYPE)
3470           && C_TYPE_FIELDS_READONLY (lhstype)))
3471     readonly_error (lhs, lv_assign);
3472
3473   /* If storing into a structure or union member,
3474      it has probably been given type `int'.
3475      Compute the type that would go with
3476      the actual amount of storage the member occupies.  */
3477
3478   if (TREE_CODE (lhs) == COMPONENT_REF
3479       && (TREE_CODE (lhstype) == INTEGER_TYPE
3480           || TREE_CODE (lhstype) == BOOLEAN_TYPE
3481           || TREE_CODE (lhstype) == REAL_TYPE
3482           || TREE_CODE (lhstype) == ENUMERAL_TYPE))
3483     lhstype = TREE_TYPE (get_unwidened (lhs, 0));
3484
3485   /* If storing in a field that is in actuality a short or narrower than one,
3486      we must store in the field in its actual type.  */
3487
3488   if (lhstype != TREE_TYPE (lhs))
3489     {
3490       lhs = copy_node (lhs);
3491       TREE_TYPE (lhs) = lhstype;
3492     }
3493
3494   /* Convert new value to destination type.  */
3495
3496   newrhs = convert_for_assignment (lhstype, newrhs, ic_assign,
3497                                    NULL_TREE, NULL_TREE, 0);
3498   if (TREE_CODE (newrhs) == ERROR_MARK)
3499     return error_mark_node;
3500
3501   /* Emit ObjC write barrier, if necessary.  */
3502   if (c_dialect_objc () && flag_objc_gc)
3503     {
3504       result = objc_generate_write_barrier (lhs, modifycode, newrhs);
3505       if (result)
3506         return result;
3507     }
3508
3509   /* Scan operands.  */
3510
3511   result = build2 (MODIFY_EXPR, lhstype, lhs, newrhs);
3512   TREE_SIDE_EFFECTS (result) = 1;
3513
3514   /* If we got the LHS in a different type for storing in,
3515      convert the result back to the nominal type of LHS
3516      so that the value we return always has the same type
3517      as the LHS argument.  */
3518
3519   if (olhstype == TREE_TYPE (result))
3520     return result;
3521   return convert_for_assignment (olhstype, result, ic_assign,
3522                                  NULL_TREE, NULL_TREE, 0);
3523 }
3524 \f
3525 /* Convert value RHS to type TYPE as preparation for an assignment
3526    to an lvalue of type TYPE.
3527    The real work of conversion is done by `convert'.
3528    The purpose of this function is to generate error messages
3529    for assignments that are not allowed in C.
3530    ERRTYPE says whether it is argument passing, assignment,
3531    initialization or return.
3532
3533    FUNCTION is a tree for the function being called.
3534    PARMNUM is the number of the argument, for printing in error messages.  */
3535
3536 static tree
3537 convert_for_assignment (tree type, tree rhs, enum impl_conv errtype,
3538                         tree fundecl, tree function, int parmnum)
3539 {
3540   enum tree_code codel = TREE_CODE (type);
3541   tree rhstype;
3542   enum tree_code coder;
3543   tree rname = NULL_TREE;
3544   bool objc_ok = false;
3545
3546   if (errtype == ic_argpass || errtype == ic_argpass_nonproto)
3547     {
3548       tree selector;
3549       /* Change pointer to function to the function itself for
3550          diagnostics.  */
3551       if (TREE_CODE (function) == ADDR_EXPR
3552           && TREE_CODE (TREE_OPERAND (function, 0)) == FUNCTION_DECL)
3553         function = TREE_OPERAND (function, 0);
3554
3555       /* Handle an ObjC selector specially for diagnostics.  */
3556       selector = objc_message_selector ();
3557       rname = function;
3558       if (selector && parmnum > 2)
3559         {
3560           rname = selector;
3561           parmnum -= 2;
3562         }
3563     }
3564
3565   /* This macro is used to emit diagnostics to ensure that all format
3566      strings are complete sentences, visible to gettext and checked at
3567      compile time.  */
3568 #define WARN_FOR_ASSIGNMENT(AR, AS, IN, RE)     \
3569   do {                                          \
3570     switch (errtype)                            \
3571       {                                         \
3572       case ic_argpass:                          \
3573         pedwarn (AR, parmnum, rname);           \
3574         break;                                  \
3575       case ic_argpass_nonproto:                 \
3576         warning (0, AR, parmnum, rname);                \
3577         break;                                  \
3578       case ic_assign:                           \
3579         pedwarn (AS);                           \
3580         break;                                  \
3581       case ic_init:                             \
3582         pedwarn (IN);                           \
3583         break;                                  \
3584       case ic_return:                           \
3585         pedwarn (RE);                           \
3586         break;                                  \
3587       default:                                  \
3588         gcc_unreachable ();                     \
3589       }                                         \
3590   } while (0)
3591
3592   STRIP_TYPE_NOPS (rhs);
3593
3594   if (optimize && TREE_CODE (rhs) == VAR_DECL
3595            && TREE_CODE (TREE_TYPE (rhs)) != ARRAY_TYPE)
3596     rhs = decl_constant_value_for_broken_optimization (rhs);
3597
3598   rhstype = TREE_TYPE (rhs);
3599   coder = TREE_CODE (rhstype);
3600
3601   if (coder == ERROR_MARK)
3602     return error_mark_node;
3603
3604   if (c_dialect_objc ())
3605     {
3606       int parmno;
3607
3608       switch (errtype)
3609         {
3610         case ic_return:
3611           parmno = 0;
3612           break;
3613
3614         case ic_assign:
3615           parmno = -1;
3616           break;
3617
3618         case ic_init:
3619           parmno = -2;
3620           break;
3621
3622         default:
3623           parmno = parmnum;
3624           break;
3625         }
3626
3627       objc_ok = objc_compare_types (type, rhstype, parmno, rname);
3628     }
3629
3630   if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (rhstype))
3631     {
3632       overflow_warning (rhs);
3633       return rhs;
3634     }
3635
3636   if (coder == VOID_TYPE)
3637     {
3638       /* Except for passing an argument to an unprototyped function,
3639          this is a constraint violation.  When passing an argument to
3640          an unprototyped function, it is compile-time undefined;
3641          making it a constraint in that case was rejected in
3642          DR#252.  */
3643       error ("void value not ignored as it ought to be");
3644       return error_mark_node;
3645     }
3646   /* A type converts to a reference to it.
3647      This code doesn't fully support references, it's just for the
3648      special case of va_start and va_copy.  */
3649   if (codel == REFERENCE_TYPE
3650       && comptypes (TREE_TYPE (type), TREE_TYPE (rhs)) == 1)
3651     {
3652       if (!lvalue_p (rhs))
3653         {
3654           error ("cannot pass rvalue to reference parameter");
3655           return error_mark_node;
3656         }
3657       if (!c_mark_addressable (rhs))
3658         return error_mark_node;
3659       rhs = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (rhs)), rhs);
3660
3661       /* We already know that these two types are compatible, but they
3662          may not be exactly identical.  In fact, `TREE_TYPE (type)' is
3663          likely to be __builtin_va_list and `TREE_TYPE (rhs)' is
3664          likely to be va_list, a typedef to __builtin_va_list, which
3665          is different enough that it will cause problems later.  */
3666       if (TREE_TYPE (TREE_TYPE (rhs)) != TREE_TYPE (type))
3667         rhs = build1 (NOP_EXPR, build_pointer_type (TREE_TYPE (type)), rhs);
3668
3669       rhs = build1 (NOP_EXPR, type, rhs);
3670       return rhs;
3671     }
3672   /* Some types can interconvert without explicit casts.  */
3673   else if (codel == VECTOR_TYPE && coder == VECTOR_TYPE
3674            && vector_types_convertible_p (type, TREE_TYPE (rhs)))
3675     return convert (type, rhs);
3676   /* Arithmetic types all interconvert, and enum is treated like int.  */
3677   else if ((codel == INTEGER_TYPE || codel == REAL_TYPE
3678             || codel == ENUMERAL_TYPE || codel == COMPLEX_TYPE
3679             || codel == BOOLEAN_TYPE)
3680            && (coder == INTEGER_TYPE || coder == REAL_TYPE
3681                || coder == ENUMERAL_TYPE || coder == COMPLEX_TYPE
3682                || coder == BOOLEAN_TYPE))
3683     return convert_and_check (type, rhs);
3684
3685   /* Conversion to a transparent union from its member types.
3686      This applies only to function arguments.  */
3687   else if (codel == UNION_TYPE && TYPE_TRANSPARENT_UNION (type)
3688            && (errtype == ic_argpass || errtype == ic_argpass_nonproto))
3689     {
3690       tree memb_types;
3691       tree marginal_memb_type = 0;
3692
3693       for (memb_types = TYPE_FIELDS (type); memb_types;
3694            memb_types = TREE_CHAIN (memb_types))
3695         {
3696           tree memb_type = TREE_TYPE (memb_types);
3697
3698           if (comptypes (TYPE_MAIN_VARIANT (memb_type),
3699                          TYPE_MAIN_VARIANT (rhstype)))
3700             break;
3701
3702           if (TREE_CODE (memb_type) != POINTER_TYPE)
3703             continue;
3704
3705           if (coder == POINTER_TYPE)
3706             {
3707               tree ttl = TREE_TYPE (memb_type);
3708               tree ttr = TREE_TYPE (rhstype);
3709
3710               /* Any non-function converts to a [const][volatile] void *
3711                  and vice versa; otherwise, targets must be the same.
3712                  Meanwhile, the lhs target must have all the qualifiers of
3713                  the rhs.  */
3714               if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
3715                   || comp_target_types (memb_type, rhstype))
3716                 {
3717                   /* If this type won't generate any warnings, use it.  */
3718                   if (TYPE_QUALS (ttl) == TYPE_QUALS (ttr)
3719                       || ((TREE_CODE (ttr) == FUNCTION_TYPE
3720                            && TREE_CODE (ttl) == FUNCTION_TYPE)
3721                           ? ((TYPE_QUALS (ttl) | TYPE_QUALS (ttr))
3722                              == TYPE_QUALS (ttr))
3723                           : ((TYPE_QUALS (ttl) | TYPE_QUALS (ttr))
3724                              == TYPE_QUALS (ttl))))
3725                     break;
3726
3727                   /* Keep looking for a better type, but remember this one.  */
3728                   if (!marginal_memb_type)
3729                     marginal_memb_type = memb_type;
3730                 }
3731             }
3732
3733           /* Can convert integer zero to any pointer type.  */
3734           if (integer_zerop (rhs)
3735               || (TREE_CODE (rhs) == NOP_EXPR
3736                   && integer_zerop (TREE_OPERAND (rhs, 0))))
3737             {
3738               rhs = null_pointer_node;
3739               break;
3740             }
3741         }
3742
3743       if (memb_types || marginal_memb_type)
3744         {
3745           if (!memb_types)
3746             {
3747               /* We have only a marginally acceptable member type;
3748                  it needs a warning.  */
3749               tree ttl = TREE_TYPE (marginal_memb_type);
3750               tree ttr = TREE_TYPE (rhstype);
3751
3752               /* Const and volatile mean something different for function
3753                  types, so the usual warnings are not appropriate.  */
3754               if (TREE_CODE (ttr) == FUNCTION_TYPE
3755                   && TREE_CODE (ttl) == FUNCTION_TYPE)
3756                 {
3757                   /* Because const and volatile on functions are
3758                      restrictions that say the function will not do
3759                      certain things, it is okay to use a const or volatile
3760                      function where an ordinary one is wanted, but not
3761                      vice-versa.  */
3762                   if (TYPE_QUALS (ttl) & ~TYPE_QUALS (ttr))
3763                     WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE "
3764                                             "makes qualified function "
3765                                             "pointer from unqualified"),
3766                                          G_("assignment makes qualified "
3767                                             "function pointer from "
3768                                             "unqualified"),
3769                                          G_("initialization makes qualified "
3770                                             "function pointer from "
3771                                             "unqualified"),
3772                                          G_("return makes qualified function "
3773                                             "pointer from unqualified"));
3774                 }
3775               else if (TYPE_QUALS (ttr) & ~TYPE_QUALS (ttl))
3776                 WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE discards "
3777                                         "qualifiers from pointer target type"),
3778                                      G_("assignment discards qualifiers "
3779                                         "from pointer target type"),
3780                                      G_("initialization discards qualifiers "
3781                                         "from pointer target type"),
3782                                      G_("return discards qualifiers from "
3783                                         "pointer target type"));
3784             }
3785
3786           if (pedantic && (!fundecl || !DECL_IN_SYSTEM_HEADER (fundecl)))
3787             pedwarn ("ISO C prohibits argument conversion to union type");
3788
3789           return build1 (NOP_EXPR, type, rhs);
3790         }
3791     }
3792
3793   /* Conversions among pointers */
3794   else if ((codel == POINTER_TYPE || codel == REFERENCE_TYPE)
3795            && (coder == codel))
3796     {
3797       tree ttl = TREE_TYPE (type);
3798       tree ttr = TREE_TYPE (rhstype);
3799       tree mvl = ttl;
3800       tree mvr = ttr;
3801       bool is_opaque_pointer;
3802       int target_cmp = 0;   /* Cache comp_target_types () result.  */
3803
3804       if (TREE_CODE (mvl) != ARRAY_TYPE)
3805         mvl = TYPE_MAIN_VARIANT (mvl);
3806       if (TREE_CODE (mvr) != ARRAY_TYPE)
3807         mvr = TYPE_MAIN_VARIANT (mvr);
3808       /* Opaque pointers are treated like void pointers.  */
3809       is_opaque_pointer = (targetm.vector_opaque_p (type)
3810                            || targetm.vector_opaque_p (rhstype))
3811         && TREE_CODE (ttl) == VECTOR_TYPE
3812         && TREE_CODE (ttr) == VECTOR_TYPE;
3813
3814       /* C++ does not allow the implicit conversion void* -> T*.  However,
3815          for the purpose of reducing the number of false positives, we
3816          tolerate the special case of
3817
3818                 int *p = NULL;
3819
3820          where NULL is typically defined in C to be '(void *) 0'.  */
3821       if (VOID_TYPE_P (ttr) && rhs != null_pointer_node && !VOID_TYPE_P (ttl))
3822         warning (OPT_Wc___compat, "request for implicit conversion from "
3823                  "%qT to %qT not permitted in C++", rhstype, type);
3824
3825       /* Check if the right-hand side has a format attribute but the
3826          left-hand side doesn't.  */
3827       if (warn_missing_format_attribute
3828           && check_missing_format_attribute (type, rhstype))
3829         {
3830           switch (errtype)
3831           {
3832           case ic_argpass:
3833           case ic_argpass_nonproto:
3834             warning (OPT_Wmissing_format_attribute,
3835                      "argument %d of %qE might be "
3836                      "a candidate for a format attribute",
3837                      parmnum, rname);
3838             break;
3839           case ic_assign:
3840             warning (OPT_Wmissing_format_attribute,
3841                      "assignment left-hand side might be "
3842                      "a candidate for a format attribute");
3843             break;
3844           case ic_init:
3845             warning (OPT_Wmissing_format_attribute,
3846                      "initialization left-hand side might be "
3847                      "a candidate for a format attribute");
3848             break;
3849           case ic_return:
3850             warning (OPT_Wmissing_format_attribute,
3851                      "return type might be "
3852                      "a candidate for a format attribute");
3853             break;
3854           default:
3855             gcc_unreachable ();
3856           }
3857         }
3858
3859       /* Any non-function converts to a [const][volatile] void *
3860          and vice versa; otherwise, targets must be the same.
3861          Meanwhile, the lhs target must have all the qualifiers of the rhs.  */
3862       if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
3863           || (target_cmp = comp_target_types (type, rhstype))
3864           || is_opaque_pointer
3865           || (c_common_unsigned_type (mvl)
3866               == c_common_unsigned_type (mvr)))
3867         {
3868           if (pedantic
3869               && ((VOID_TYPE_P (ttl) && TREE_CODE (ttr) == FUNCTION_TYPE)
3870                   ||
3871                   (VOID_TYPE_P (ttr)
3872                    /* Check TREE_CODE to catch cases like (void *) (char *) 0
3873                       which are not ANSI null ptr constants.  */
3874                    && (!integer_zerop (rhs) || TREE_CODE (rhs) == NOP_EXPR)
3875                    && TREE_CODE (ttl) == FUNCTION_TYPE)))
3876             WARN_FOR_ASSIGNMENT (G_("ISO C forbids passing argument %d of "
3877                                     "%qE between function pointer "
3878                                     "and %<void *%>"),
3879                                  G_("ISO C forbids assignment between "
3880                                     "function pointer and %<void *%>"),
3881                                  G_("ISO C forbids initialization between "
3882                                     "function pointer and %<void *%>"),
3883                                  G_("ISO C forbids return between function "
3884                                     "pointer and %<void *%>"));
3885           /* Const and volatile mean something different for function types,
3886              so the usual warnings are not appropriate.  */
3887           else if (TREE_CODE (ttr) != FUNCTION_TYPE
3888                    && TREE_CODE (ttl) != FUNCTION_TYPE)
3889             {
3890               if (TYPE_QUALS (ttr) & ~TYPE_QUALS (ttl))
3891                 {
3892                   /* Types differing only by the presence of the 'volatile'
3893                      qualifier are acceptable if the 'volatile' has been added
3894                      in by the Objective-C EH machinery.  */
3895                   if (!objc_type_quals_match (ttl, ttr))
3896                     WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE discards "
3897                                             "qualifiers from pointer target type"),
3898                                          G_("assignment discards qualifiers "
3899                                             "from pointer target type"),
3900                                          G_("initialization discards qualifiers "
3901                                             "from pointer target type"),
3902                                          G_("return discards qualifiers from "
3903                                             "pointer target type"));
3904                 }
3905               /* If this is not a case of ignoring a mismatch in signedness,
3906                  no warning.  */
3907               else if (VOID_TYPE_P (ttl) || VOID_TYPE_P (ttr)
3908                        || target_cmp)
3909                 ;
3910               /* If there is a mismatch, do warn.  */
3911               else if (warn_pointer_sign)
3912                 WARN_FOR_ASSIGNMENT (G_("pointer targets in passing argument "
3913                                         "%d of %qE differ in signedness"),
3914                                      G_("pointer targets in assignment "
3915                                         "differ in signedness"),
3916                                      G_("pointer targets in initialization "
3917                                         "differ in signedness"),
3918                                      G_("pointer targets in return differ "
3919                                         "in signedness"));
3920             }
3921           else if (TREE_CODE (ttl) == FUNCTION_TYPE
3922                    && TREE_CODE (ttr) == FUNCTION_TYPE)
3923             {
3924               /* Because const and volatile on functions are restrictions
3925                  that say the function will not do certain things,
3926                  it is okay to use a const or volatile function
3927                  where an ordinary one is wanted, but not vice-versa.  */
3928               if (TYPE_QUALS (ttl) & ~TYPE_QUALS (ttr))
3929                 WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE makes "
3930                                         "qualified function pointer "
3931                                         "from unqualified"),
3932                                      G_("assignment makes qualified function "
3933                                         "pointer from unqualified"),
3934                                      G_("initialization makes qualified "
3935                                         "function pointer from unqualified"),
3936                                      G_("return makes qualified function "
3937                                         "pointer from unqualified"));
3938             }
3939         }
3940       else
3941         /* Avoid warning about the volatile ObjC EH puts on decls.  */
3942         if (!objc_ok)
3943           WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE from "
3944                                   "incompatible pointer type"),
3945                                G_("assignment from incompatible pointer type"),
3946                                G_("initialization from incompatible "
3947                                   "pointer type"),
3948                                G_("return from incompatible pointer type"));
3949
3950       return convert (type, rhs);
3951     }
3952   else if (codel == POINTER_TYPE && coder == ARRAY_TYPE)
3953     {
3954       /* ??? This should not be an error when inlining calls to
3955          unprototyped functions.  */
3956       error ("invalid use of non-lvalue array");
3957       return error_mark_node;
3958     }
3959   else if (codel == POINTER_TYPE && coder == INTEGER_TYPE)
3960     {
3961       /* An explicit constant 0 can convert to a pointer,
3962          or one that results from arithmetic, even including
3963          a cast to integer type.  */
3964       if (!(TREE_CODE (rhs) == INTEGER_CST && integer_zerop (rhs))
3965           &&
3966           !(TREE_CODE (rhs) == NOP_EXPR
3967             && TREE_CODE (TREE_TYPE (rhs)) == INTEGER_TYPE
3968             && TREE_CODE (TREE_OPERAND (rhs, 0)) == INTEGER_CST
3969             && integer_zerop (TREE_OPERAND (rhs, 0))))
3970         WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE makes "
3971                                 "pointer from integer without a cast"),
3972                              G_("assignment makes pointer from integer "
3973                                 "without a cast"),
3974                              G_("initialization makes pointer from "
3975                                 "integer without a cast"),
3976                              G_("return makes pointer from integer "
3977                                 "without a cast"));
3978
3979       return convert (type, rhs);
3980     }
3981   else if (codel == INTEGER_TYPE && coder == POINTER_TYPE)
3982     {
3983       WARN_FOR_ASSIGNMENT (G_("passing argument %d of %qE makes integer "
3984                               "from pointer without a cast"),
3985                            G_("assignment makes integer from pointer "
3986                               "without a cast"),
3987                            G_("initialization makes integer from pointer "
3988                               "without a cast"),
3989                            G_("return makes integer from pointer "
3990                               "without a cast"));
3991       return convert (type, rhs);
3992     }
3993   else if (codel == BOOLEAN_TYPE && coder == POINTER_TYPE)
3994     return convert (type, rhs);
3995
3996   switch (errtype)
3997     {
3998     case ic_argpass:
3999     case ic_argpass_nonproto:
4000       /* ??? This should not be an error when inlining calls to
4001          unprototyped functions.  */
4002       error ("incompatible type for argument %d of %qE", parmnum, rname);
4003       break;
4004     case ic_assign:
4005       error ("incompatible types in assignment");
4006       break;
4007     case ic_init:
4008       error ("incompatible types in initialization");
4009       break;
4010     case ic_return:
4011       error ("incompatible types in return");
4012       break;
4013     default:
4014       gcc_unreachable ();
4015     }
4016
4017   return error_mark_node;
4018 }
4019
4020 /* Convert VALUE for assignment into inlined parameter PARM.  ARGNUM
4021    is used for error and waring reporting and indicates which argument
4022    is being processed.  */
4023
4024 tree
4025 c_convert_parm_for_inlining (tree parm, tree value, tree fn, int argnum)
4026 {
4027   tree ret, type;
4028
4029   /* If FN was prototyped, the value has been converted already
4030      in convert_arguments.  */
4031   if (!value || TYPE_ARG_TYPES (TREE_TYPE (fn)))
4032     return value;
4033
4034   type = TREE_TYPE (parm);
4035   ret = convert_for_assignment (type, value,
4036                                 ic_argpass_nonproto, fn,
4037                                 fn, argnum);
4038   if (targetm.calls.promote_prototypes (TREE_TYPE (fn))
4039       && INTEGRAL_TYPE_P (type)
4040       && (TYPE_PRECISION (type) < TYPE_PRECISION (integer_type_node)))
4041     ret = default_conversion (ret);
4042   return ret;
4043 }
4044 \f
4045 /* If VALUE is a compound expr all of whose expressions are constant, then
4046    return its value.  Otherwise, return error_mark_node.
4047
4048    This is for handling COMPOUND_EXPRs as initializer elements
4049    which is allowed with a warning when -pedantic is specified.  */
4050
4051 static tree
4052 valid_compound_expr_initializer (tree value, tree endtype)
4053 {
4054   if (TREE_CODE (value) == COMPOUND_EXPR)
4055     {
4056       if (valid_compound_expr_initializer (TREE_OPERAND (value, 0), endtype)
4057           == error_mark_node)
4058         return error_mark_node;
4059       return valid_compound_expr_initializer (TREE_OPERAND (value, 1),
4060                                               endtype);
4061     }
4062   else if (!initializer_constant_valid_p (value, endtype))
4063     return error_mark_node;
4064   else
4065     return value;
4066 }
4067 \f
4068 /* Perform appropriate conversions on the initial value of a variable,
4069    store it in the declaration DECL,
4070    and print any error messages that are appropriate.
4071    If the init is invalid, store an ERROR_MARK.  */
4072
4073 void
4074 store_init_value (tree decl, tree init)
4075 {
4076   tree value, type;
4077
4078   /* If variable's type was invalidly declared, just ignore it.  */
4079
4080   type = TREE_TYPE (decl);
4081   if (TREE_CODE (type) == ERROR_MARK)
4082     return;
4083
4084   /* Digest the specified initializer into an expression.  */
4085
4086   value = digest_init (type, init, true, TREE_STATIC (decl));
4087
4088   /* Store the expression if valid; else report error.  */
4089
4090   if (!in_system_header
4091       && AGGREGATE_TYPE_P (TREE_TYPE (decl)) && !TREE_STATIC (decl))
4092     warning (OPT_Wtraditional, "traditional C rejects automatic "
4093              "aggregate initialization");
4094
4095   DECL_INITIAL (decl) = value;
4096
4097   /* ANSI wants warnings about out-of-range constant initializers.  */
4098   STRIP_TYPE_NOPS (value);
4099   constant_expression_warning (value);
4100
4101   /* Check if we need to set array size from compound literal size.  */
4102   if (TREE_CODE (type) == ARRAY_TYPE
4103       && TYPE_DOMAIN (type) == 0
4104       && value != error_mark_node)
4105     {
4106       tree inside_init = init;
4107
4108       STRIP_TYPE_NOPS (inside_init);
4109       inside_init = fold (inside_init);
4110
4111       if (TREE_CODE (inside_init) == COMPOUND_LITERAL_EXPR)
4112         {
4113           tree decl = COMPOUND_LITERAL_EXPR_DECL (inside_init);
4114
4115           if (TYPE_DOMAIN (TREE_TYPE (decl)))
4116             {
4117               /* For int foo[] = (int [3]){1}; we need to set array size
4118                  now since later on array initializer will be just the
4119                  brace enclosed list of the compound literal.  */
4120               TYPE_DOMAIN (type) = TYPE_DOMAIN (TREE_TYPE (decl));
4121               layout_type (type);
4122               layout_decl (decl, 0);
4123             }
4124         }
4125     }
4126 }
4127 \f
4128 /* Methods for storing and printing names for error messages.  */
4129
4130 /* Implement a spelling stack that allows components of a name to be pushed
4131    and popped.  Each element on the stack is this structure.  */
4132
4133 struct spelling
4134 {
4135   int kind;
4136   union
4137     {
4138       int i;
4139       const char *s;
4140     } u;
4141 };
4142
4143 #define SPELLING_STRING 1
4144 #define SPELLING_MEMBER 2
4145 #define SPELLING_BOUNDS 3
4146
4147 static struct spelling *spelling;       /* Next stack element (unused).  */
4148 static struct spelling *spelling_base;  /* Spelling stack base.  */
4149 static int spelling_size;               /* Size of the spelling stack.  */
4150
4151 /* Macros to save and restore the spelling stack around push_... functions.
4152    Alternative to SAVE_SPELLING_STACK.  */
4153
4154 #define SPELLING_DEPTH() (spelling - spelling_base)
4155 #define RESTORE_SPELLING_DEPTH(DEPTH) (spelling = spelling_base + (DEPTH))
4156
4157 /* Push an element on the spelling stack with type KIND and assign VALUE
4158    to MEMBER.  */
4159
4160 #define PUSH_SPELLING(KIND, VALUE, MEMBER)                              \
4161 {                                                                       \
4162   int depth = SPELLING_DEPTH ();                                        \
4163                                                                         \
4164   if (depth >= spelling_size)                                           \
4165     {                                                                   \
4166       spelling_size += 10;                                              \
4167       spelling_base = XRESIZEVEC (struct spelling, spelling_base,       \
4168                                   spelling_size);                       \
4169       RESTORE_SPELLING_DEPTH (depth);                                   \
4170     }                                                                   \
4171                                                                         \
4172   spelling->kind = (KIND);                                              \
4173   spelling->MEMBER = (VALUE);                                           \
4174   spelling++;                                                           \
4175 }
4176
4177 /* Push STRING on the stack.  Printed literally.  */
4178
4179 static void
4180 push_string (const char *string)
4181 {
4182   PUSH_SPELLING (SPELLING_STRING, string, u.s);
4183 }
4184
4185 /* Push a member name on the stack.  Printed as '.' STRING.  */
4186
4187 static void
4188 push_member_name (tree decl)
4189 {
4190   const char *const string
4191     = DECL_NAME (decl) ? IDENTIFIER_POINTER (DECL_NAME (decl)) : "<anonymous>";
4192   PUSH_SPELLING (SPELLING_MEMBER, string, u.s);
4193 }
4194
4195 /* Push an array bounds on the stack.  Printed as [BOUNDS].  */
4196
4197 static void
4198 push_array_bounds (int bounds)
4199 {
4200   PUSH_SPELLING (SPELLING_BOUNDS, bounds, u.i);
4201 }
4202
4203 /* Compute the maximum size in bytes of the printed spelling.  */
4204
4205 static int
4206 spelling_length (void)
4207 {
4208   int size = 0;
4209   struct spelling *p;
4210
4211   for (p = spelling_base; p < spelling; p++)
4212     {
4213       if (p->kind == SPELLING_BOUNDS)
4214         size += 25;
4215       else
4216         size += strlen (p->u.s) + 1;
4217     }
4218
4219   return size;
4220 }
4221
4222 /* Print the spelling to BUFFER and return it.  */
4223
4224 static char *
4225 print_spelling (char *buffer)
4226 {
4227   char *d = buffer;
4228   struct spelling *p;
4229
4230   for (p = spelling_base; p < spelling; p++)
4231     if (p->kind == SPELLING_BOUNDS)
4232       {
4233         sprintf (d, "[%d]", p->u.i);
4234         d += strlen (d);
4235       }
4236     else
4237       {
4238         const char *s;
4239         if (p->kind == SPELLING_MEMBER)
4240           *d++ = '.';
4241         for (s = p->u.s; (*d = *s++); d++)
4242           ;
4243       }
4244   *d++ = '\0';
4245   return buffer;
4246 }
4247
4248 /* Issue an error message for a bad initializer component.
4249    MSGID identifies the message.
4250    The component name is taken from the spelling stack.  */
4251
4252 void
4253 error_init (const char *msgid)
4254 {
4255   char *ofwhat;
4256
4257   error ("%s", _(msgid));
4258   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4259   if (*ofwhat)
4260     error ("(near initialization for %qs)", ofwhat);
4261 }
4262
4263 /* Issue a pedantic warning for a bad initializer component.
4264    MSGID identifies the message.
4265    The component name is taken from the spelling stack.  */
4266
4267 void
4268 pedwarn_init (const char *msgid)
4269 {
4270   char *ofwhat;
4271
4272   pedwarn ("%s", _(msgid));
4273   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4274   if (*ofwhat)
4275     pedwarn ("(near initialization for %qs)", ofwhat);
4276 }
4277
4278 /* Issue a warning for a bad initializer component.
4279    MSGID identifies the message.
4280    The component name is taken from the spelling stack.  */
4281
4282 static void
4283 warning_init (const char *msgid)
4284 {
4285   char *ofwhat;
4286
4287   warning (0, "%s", _(msgid));
4288   ofwhat = print_spelling ((char *) alloca (spelling_length () + 1));
4289   if (*ofwhat)
4290     warning (0, "(near initialization for %qs)", ofwhat);
4291 }
4292 \f
4293 /* If TYPE is an array type and EXPR is a parenthesized string
4294    constant, warn if pedantic that EXPR is being used to initialize an
4295    object of type TYPE.  */
4296
4297 void
4298 maybe_warn_string_init (tree type, struct c_expr expr)
4299 {
4300   if (pedantic
4301       && TREE_CODE (type) == ARRAY_TYPE
4302       && TREE_CODE (expr.value) == STRING_CST
4303       && expr.original_code != STRING_CST)
4304     pedwarn_init ("array initialized from parenthesized string constant");
4305 }
4306
4307 /* Digest the parser output INIT as an initializer for type TYPE.
4308    Return a C expression of type TYPE to represent the initial value.
4309
4310    If INIT is a string constant, STRICT_STRING is true if it is
4311    unparenthesized or we should not warn here for it being parenthesized.
4312    For other types of INIT, STRICT_STRING is not used.
4313
4314    REQUIRE_CONSTANT requests an error if non-constant initializers or
4315    elements are seen.  */
4316
4317 static tree
4318 digest_init (tree type, tree init, bool strict_string, int require_constant)
4319 {
4320   enum tree_code code = TREE_CODE (type);
4321   tree inside_init = init;
4322
4323   if (type == error_mark_node
4324       || init == error_mark_node
4325       || TREE_TYPE (init) == error_mark_node)
4326     return error_mark_node;
4327
4328   STRIP_TYPE_NOPS (inside_init);
4329
4330   inside_init = fold (inside_init);
4331
4332   /* Initialization of an array of chars from a string constant
4333      optionally enclosed in braces.  */
4334
4335   if (code == ARRAY_TYPE && inside_init
4336       && TREE_CODE (inside_init) == STRING_CST)
4337     {
4338       tree typ1 = TYPE_MAIN_VARIANT (TREE_TYPE (type));
4339       /* Note that an array could be both an array of character type
4340          and an array of wchar_t if wchar_t is signed char or unsigned
4341          char.  */
4342       bool char_array = (typ1 == char_type_node
4343                          || typ1 == signed_char_type_node
4344                          || typ1 == unsigned_char_type_node);
4345       bool wchar_array = !!comptypes (typ1, wchar_type_node);
4346       if (char_array || wchar_array)
4347         {
4348           struct c_expr expr;
4349           bool char_string;
4350           expr.value = inside_init;
4351           expr.original_code = (strict_string ? STRING_CST : ERROR_MARK);
4352           maybe_warn_string_init (type, expr);
4353
4354           char_string
4355             = (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (inside_init)))
4356                == char_type_node);
4357
4358           if (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4359                          TYPE_MAIN_VARIANT (type)))
4360             return inside_init;
4361
4362           if (!wchar_array && !char_string)
4363             {
4364               error_init ("char-array initialized from wide string");
4365               return error_mark_node;
4366             }
4367           if (char_string && !char_array)
4368             {
4369               error_init ("wchar_t-array initialized from non-wide string");
4370               return error_mark_node;
4371             }
4372
4373           TREE_TYPE (inside_init) = type;
4374           if (TYPE_DOMAIN (type) != 0
4375               && TYPE_SIZE (type) != 0
4376               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
4377               /* Subtract 1 (or sizeof (wchar_t))
4378                  because it's ok to ignore the terminating null char
4379                  that is counted in the length of the constant.  */
4380               && 0 > compare_tree_int (TYPE_SIZE_UNIT (type),
4381                                        TREE_STRING_LENGTH (inside_init)
4382                                        - ((TYPE_PRECISION (typ1)
4383                                            != TYPE_PRECISION (char_type_node))
4384                                           ? (TYPE_PRECISION (wchar_type_node)
4385                                              / BITS_PER_UNIT)
4386                                           : 1)))
4387             pedwarn_init ("initializer-string for array of chars is too long");
4388
4389           return inside_init;
4390         }
4391       else if (INTEGRAL_TYPE_P (typ1))
4392         {
4393           error_init ("array of inappropriate type initialized "
4394                       "from string constant");
4395           return error_mark_node;
4396         }
4397     }
4398
4399   /* Build a VECTOR_CST from a *constant* vector constructor.  If the
4400      vector constructor is not constant (e.g. {1,2,3,foo()}) then punt
4401      below and handle as a constructor.  */
4402   if (code == VECTOR_TYPE
4403       && TREE_CODE (TREE_TYPE (inside_init)) == VECTOR_TYPE
4404       && vector_types_convertible_p (TREE_TYPE (inside_init), type)
4405       && TREE_CONSTANT (inside_init))
4406     {
4407       if (TREE_CODE (inside_init) == VECTOR_CST
4408           && comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4409                         TYPE_MAIN_VARIANT (type)))
4410         return inside_init;
4411
4412       if (TREE_CODE (inside_init) == CONSTRUCTOR)
4413         {
4414           unsigned HOST_WIDE_INT ix;
4415           tree value;
4416           bool constant_p = true;
4417
4418           /* Iterate through elements and check if all constructor
4419              elements are *_CSTs.  */
4420           FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (inside_init), ix, value)
4421             if (!CONSTANT_CLASS_P (value))
4422               {
4423                 constant_p = false;
4424                 break;
4425               }
4426
4427           if (constant_p)
4428             return build_vector_from_ctor (type,
4429                                            CONSTRUCTOR_ELTS (inside_init));
4430         }
4431     }
4432
4433   /* Any type can be initialized
4434      from an expression of the same type, optionally with braces.  */
4435
4436   if (inside_init && TREE_TYPE (inside_init) != 0
4437       && (comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (inside_init)),
4438                      TYPE_MAIN_VARIANT (type))
4439           || (code == ARRAY_TYPE
4440               && comptypes (TREE_TYPE (inside_init), type))
4441           || (code == VECTOR_TYPE
4442               && comptypes (TREE_TYPE (inside_init), type))
4443           || (code == POINTER_TYPE
4444               && TREE_CODE (TREE_TYPE (inside_init)) == ARRAY_TYPE
4445               && comptypes (TREE_TYPE (TREE_TYPE (inside_init)),
4446                             TREE_TYPE (type)))))
4447     {
4448       if (code == POINTER_TYPE)
4449         {
4450           if (TREE_CODE (TREE_TYPE (inside_init)) == ARRAY_TYPE)
4451             {
4452               if (TREE_CODE (inside_init) == STRING_CST
4453                   || TREE_CODE (inside_init) == COMPOUND_LITERAL_EXPR)
4454                 inside_init = array_to_pointer_conversion (inside_init);
4455               else
4456                 {
4457                   error_init ("invalid use of non-lvalue array");
4458                   return error_mark_node;
4459                 }
4460             }
4461         }
4462
4463       if (code == VECTOR_TYPE)
4464         /* Although the types are compatible, we may require a
4465            conversion.  */
4466         inside_init = convert (type, inside_init);
4467
4468       if (require_constant && !flag_isoc99
4469           && TREE_CODE (inside_init) == COMPOUND_LITERAL_EXPR)
4470         {
4471           /* As an extension, allow initializing objects with static storage
4472              duration with compound literals (which are then treated just as
4473              the brace enclosed list they contain).  */
4474           tree decl = COMPOUND_LITERAL_EXPR_DECL (inside_init);
4475           inside_init = DECL_INITIAL (decl);
4476         }
4477
4478       if (code == ARRAY_TYPE && TREE_CODE (inside_init) != STRING_CST
4479           && TREE_CODE (inside_init) != CONSTRUCTOR)
4480         {
4481           error_init ("array initialized from non-constant array expression");
4482           return error_mark_node;
4483         }
4484
4485       if (optimize && TREE_CODE (inside_init) == VAR_DECL)
4486         inside_init = decl_constant_value_for_broken_optimization (inside_init);
4487
4488       /* Compound expressions can only occur here if -pedantic or
4489          -pedantic-errors is specified.  In the later case, we always want
4490          an error.  In the former case, we simply want a warning.  */
4491       if (require_constant && pedantic
4492           && TREE_CODE (inside_init) == COMPOUND_EXPR)
4493         {
4494           inside_init
4495             = valid_compound_expr_initializer (inside_init,
4496                                                TREE_TYPE (inside_init));
4497           if (inside_init == error_mark_node)
4498             error_init ("initializer element is not constant");
4499           else
4500             pedwarn_init ("initializer element is not constant");
4501           if (flag_pedantic_errors)
4502             inside_init = error_mark_node;
4503         }
4504       else if (require_constant
4505                && !initializer_constant_valid_p (inside_init,
4506                                                  TREE_TYPE (inside_init)))
4507         {
4508           error_init ("initializer element is not constant");
4509           inside_init = error_mark_node;
4510         }
4511
4512       /* Added to enable additional -Wmissing-format-attribute warnings.  */
4513       if (TREE_CODE (TREE_TYPE (inside_init)) == POINTER_TYPE)
4514         inside_init = convert_for_assignment (type, inside_init, ic_init, NULL_TREE,
4515                                               NULL_TREE, 0);
4516       return inside_init;
4517     }
4518
4519   /* Handle scalar types, including conversions.  */
4520
4521   if (code == INTEGER_TYPE || code == REAL_TYPE || code == POINTER_TYPE
4522       || code == ENUMERAL_TYPE || code == BOOLEAN_TYPE || code == COMPLEX_TYPE
4523       || code == VECTOR_TYPE)
4524     {
4525       if (TREE_CODE (TREE_TYPE (init)) == ARRAY_TYPE
4526           && (TREE_CODE (init) == STRING_CST
4527               || TREE_CODE (init) == COMPOUND_LITERAL_EXPR))
4528         init = array_to_pointer_conversion (init);
4529       inside_init
4530         = convert_for_assignment (type, init, ic_init,
4531                                   NULL_TREE, NULL_TREE, 0);
4532
4533       /* Check to see if we have already given an error message.  */
4534       if (inside_init == error_mark_node)
4535         ;
4536       else if (require_constant && !TREE_CONSTANT (inside_init))
4537         {
4538           error_init ("initializer element is not constant");
4539           inside_init = error_mark_node;
4540         }
4541       else if (require_constant
4542                && !initializer_constant_valid_p (inside_init,
4543                                                  TREE_TYPE (inside_init)))
4544         {
4545           error_init ("initializer element is not computable at load time");
4546           inside_init = error_mark_node;
4547         }
4548
4549       return inside_init;
4550     }
4551
4552   /* Come here only for records and arrays.  */
4553
4554   if (COMPLETE_TYPE_P (type) && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
4555     {
4556       error_init ("variable-sized object may not be initialized");
4557       return error_mark_node;
4558     }
4559
4560   error_init ("invalid initializer");
4561   return error_mark_node;
4562 }
4563 \f
4564 /* Handle initializers that use braces.  */
4565
4566 /* Type of object we are accumulating a constructor for.
4567    This type is always a RECORD_TYPE, UNION_TYPE or ARRAY_TYPE.  */
4568 static tree constructor_type;
4569
4570 /* For a RECORD_TYPE or UNION_TYPE, this is the chain of fields
4571    left to fill.  */
4572 static tree constructor_fields;
4573
4574 /* For an ARRAY_TYPE, this is the specified index
4575    at which to store the next element we get.  */
4576 static tree constructor_index;
4577
4578 /* For an ARRAY_TYPE, this is the maximum index.  */
4579 static tree constructor_max_index;
4580
4581 /* For a RECORD_TYPE, this is the first field not yet written out.  */
4582 static tree constructor_unfilled_fields;
4583
4584 /* For an ARRAY_TYPE, this is the index of the first element
4585    not yet written out.  */
4586 static tree constructor_unfilled_index;
4587
4588 /* In a RECORD_TYPE, the byte index of the next consecutive field.
4589    This is so we can generate gaps between fields, when appropriate.  */
4590 static tree constructor_bit_index;
4591
4592 /* If we are saving up the elements rather than allocating them,
4593    this is the list of elements so far (in reverse order,
4594    most recent first).  */
4595 static VEC(constructor_elt,gc) *constructor_elements;
4596
4597 /* 1 if constructor should be incrementally stored into a constructor chain,
4598    0 if all the elements should be kept in AVL tree.  */
4599 static int constructor_incremental;
4600
4601 /* 1 if so far this constructor's elements are all compile-time constants.  */
4602 static int constructor_constant;
4603
4604 /* 1 if so far this constructor's elements are all valid address constants.  */
4605 static int constructor_simple;
4606
4607 /* 1 if this constructor is erroneous so far.  */
4608 static int constructor_erroneous;
4609
4610 /* Structure for managing pending initializer elements, organized as an
4611    AVL tree.  */
4612
4613 struct init_node
4614 {
4615   struct init_node *left, *right;
4616   struct init_node *parent;
4617   int balance;
4618   tree purpose;
4619   tree value;
4620 };
4621
4622 /* Tree of pending elements at this constructor level.
4623    These are elements encountered out of order
4624    which belong at places we haven't reached yet in actually
4625    writing the output.
4626    Will never hold tree nodes across GC runs.  */
4627 static struct init_node *constructor_pending_elts;
4628
4629 /* The SPELLING_DEPTH of this constructor.  */
4630 static int constructor_depth;
4631
4632 /* DECL node for which an initializer is being read.
4633    0 means we are reading a constructor expression
4634    such as (struct foo) {...}.  */
4635 static tree constructor_decl;
4636
4637 /* Nonzero if this is an initializer for a top-level decl.  */
4638 static int constructor_top_level;
4639
4640 /* Nonzero if there were any member designators in this initializer.  */
4641 static int constructor_designated;
4642
4643 /* Nesting depth of designator list.  */
4644 static int designator_depth;
4645
4646 /* Nonzero if there were diagnosed errors in this designator list.  */
4647 static int designator_errorneous;
4648
4649 \f
4650 /* This stack has a level for each implicit or explicit level of
4651    structuring in the initializer, including the outermost one.  It
4652    saves the values of most of the variables above.  */
4653
4654 struct constructor_range_stack;
4655
4656 struct constructor_stack
4657 {
4658   struct constructor_stack *next;
4659   tree type;
4660   tree fields;
4661   tree index;
4662   tree max_index;
4663   tree unfilled_index;
4664   tree unfilled_fields;
4665   tree bit_index;
4666   VEC(constructor_elt,gc) *elements;
4667   struct init_node *pending_elts;
4668   int offset;
4669   int depth;
4670   /* If value nonzero, this value should replace the entire
4671      constructor at this level.  */
4672   struct c_expr replacement_value;
4673   struct constructor_range_stack *range_stack;
4674   char constant;
4675   char simple;
4676   char implicit;
4677   char erroneous;
4678   char outer;
4679   char incremental;
4680   char designated;
4681 };
4682
4683 static struct constructor_stack *constructor_stack;
4684
4685 /* This stack represents designators from some range designator up to
4686    the last designator in the list.  */
4687
4688 struct constructor_range_stack
4689 {
4690   struct constructor_range_stack *next, *prev;
4691   struct constructor_stack *stack;
4692   tree range_start;
4693   tree index;
4694   tree range_end;
4695   tree fields;
4696 };
4697
4698 static struct constructor_range_stack *constructor_range_stack;
4699
4700 /* This stack records separate initializers that are nested.
4701    Nested initializers can't happen in ANSI C, but GNU C allows them
4702    in cases like { ... (struct foo) { ... } ... }.  */
4703
4704 struct initializer_stack
4705 {
4706   struct initializer_stack *next;
4707   tree decl;
4708   struct constructor_stack *constructor_stack;
4709   struct constructor_range_stack *constructor_range_stack;
4710   VEC(constructor_elt,gc) *elements;
4711   struct spelling *spelling;
4712   struct spelling *spelling_base;
4713   int spelling_size;
4714   char top_level;
4715   char require_constant_value;
4716   char require_constant_elements;
4717 };
4718
4719 static struct initializer_stack *initializer_stack;
4720 \f
4721 /* Prepare to parse and output the initializer for variable DECL.  */
4722
4723 void
4724 start_init (tree decl, tree asmspec_tree ATTRIBUTE_UNUSED, int top_level)
4725 {
4726   const char *locus;
4727   struct initializer_stack *p = xmalloc (sizeof (struct initializer_stack));
4728
4729   p->decl = constructor_decl;
4730   p->require_constant_value = require_constant_value;
4731   p->require_constant_elements = require_constant_elements;
4732   p->constructor_stack = constructor_stack;
4733   p->constructor_range_stack = constructor_range_stack;
4734   p->elements = constructor_elements;
4735   p->spelling = spelling;
4736   p->spelling_base = spelling_base;
4737   p->spelling_size = spelling_size;
4738   p->top_level = constructor_top_level;
4739   p->next = initializer_stack;
4740   initializer_stack = p;
4741
4742   constructor_decl = decl;
4743   constructor_designated = 0;
4744   constructor_top_level = top_level;
4745
4746   if (decl != 0 && decl != error_mark_node)
4747     {
4748       require_constant_value = TREE_STATIC (decl);
4749       require_constant_elements
4750         = ((TREE_STATIC (decl) || (pedantic && !flag_isoc99))
4751            /* For a scalar, you can always use any value to initialize,
4752               even within braces.  */
4753            && (TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE
4754                || TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
4755                || TREE_CODE (TREE_TYPE (decl)) == UNION_TYPE
4756                || TREE_CODE (TREE_TYPE (decl)) == QUAL_UNION_TYPE));
4757       locus = IDENTIFIER_POINTER (DECL_NAME (decl));
4758     }
4759   else
4760     {
4761       require_constant_value = 0;
4762       require_constant_elements = 0;
4763       locus = "(anonymous)";
4764     }
4765
4766   constructor_stack = 0;
4767   constructor_range_stack = 0;
4768
4769   missing_braces_mentioned = 0;
4770
4771   spelling_base = 0;
4772   spelling_size = 0;
4773   RESTORE_SPELLING_DEPTH (0);
4774
4775   if (locus)
4776     push_string (locus);
4777 }
4778
4779 void
4780 finish_init (void)
4781 {
4782   struct initializer_stack *p = initializer_stack;
4783
4784   /* Free the whole constructor stack of this initializer.  */
4785   while (constructor_stack)
4786     {
4787       struct constructor_stack *q = constructor_stack;
4788       constructor_stack = q->next;
4789       free (q);
4790     }
4791
4792   gcc_assert (!constructor_range_stack);
4793
4794   /* Pop back to the data of the outer initializer (if any).  */
4795   free (spelling_base);
4796
4797   constructor_decl = p->decl;
4798   require_constant_value = p->require_constant_value;
4799   require_constant_elements = p->require_constant_elements;
4800   constructor_stack = p->constructor_stack;
4801   constructor_range_stack = p->constructor_range_stack;
4802   constructor_elements = p->elements;
4803   spelling = p->spelling;
4804   spelling_base = p->spelling_base;
4805   spelling_size = p->spelling_size;
4806   constructor_top_level = p->top_level;
4807   initializer_stack = p->next;
4808   free (p);
4809 }
4810 \f
4811 /* Call here when we see the initializer is surrounded by braces.
4812    This is instead of a call to push_init_level;
4813    it is matched by a call to pop_init_level.
4814
4815    TYPE is the type to initialize, for a constructor expression.
4816    For an initializer for a decl, TYPE is zero.  */
4817
4818 void
4819 really_start_incremental_init (tree type)
4820 {
4821   struct constructor_stack *p = XNEW (struct constructor_stack);
4822
4823   if (type == 0)
4824     type = TREE_TYPE (constructor_decl);
4825
4826   if (targetm.vector_opaque_p (type))
4827     error ("opaque vector types cannot be initialized");
4828
4829   p->type = constructor_type;
4830   p->fields = constructor_fields;
4831   p->index = constructor_index;
4832   p->max_index = constructor_max_index;
4833   p->unfilled_index = constructor_unfilled_index;
4834   p->unfilled_fields = constructor_unfilled_fields;
4835   p->bit_index = constructor_bit_index;
4836   p->elements = constructor_elements;
4837   p->constant = constructor_constant;
4838   p->simple = constructor_simple;
4839   p->erroneous = constructor_erroneous;
4840   p->pending_elts = constructor_pending_elts;
4841   p->depth = constructor_depth;
4842   p->replacement_value.value = 0;
4843   p->replacement_value.original_code = ERROR_MARK;
4844   p->implicit = 0;
4845   p->range_stack = 0;
4846   p->outer = 0;
4847   p->incremental = constructor_incremental;
4848   p->designated = constructor_designated;
4849   p->next = 0;
4850   constructor_stack = p;
4851
4852   constructor_constant = 1;
4853   constructor_simple = 1;
4854   constructor_depth = SPELLING_DEPTH ();
4855   constructor_elements = 0;
4856   constructor_pending_elts = 0;
4857   constructor_type = type;
4858   constructor_incremental = 1;
4859   constructor_designated = 0;
4860   designator_depth = 0;
4861   designator_errorneous = 0;
4862
4863   if (TREE_CODE (constructor_type) == RECORD_TYPE
4864       || TREE_CODE (constructor_type) == UNION_TYPE)
4865     {
4866       constructor_fields = TYPE_FIELDS (constructor_type);
4867       /* Skip any nameless bit fields at the beginning.  */
4868       while (constructor_fields != 0 && DECL_C_BIT_FIELD (constructor_fields)
4869              && DECL_NAME (constructor_fields) == 0)
4870         constructor_fields = TREE_CHAIN (constructor_fields);
4871
4872       constructor_unfilled_fields = constructor_fields;
4873       constructor_bit_index = bitsize_zero_node;
4874     }
4875   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
4876     {
4877       if (TYPE_DOMAIN (constructor_type))
4878         {
4879           constructor_max_index
4880             = TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type));
4881
4882           /* Detect non-empty initializations of zero-length arrays.  */
4883           if (constructor_max_index == NULL_TREE
4884               && TYPE_SIZE (constructor_type))
4885             constructor_max_index = build_int_cst (NULL_TREE, -1);
4886
4887           /* constructor_max_index needs to be an INTEGER_CST.  Attempts
4888              to initialize VLAs will cause a proper error; avoid tree
4889              checking errors as well by setting a safe value.  */
4890           if (constructor_max_index
4891               && TREE_CODE (constructor_max_index) != INTEGER_CST)
4892             constructor_max_index = build_int_cst (NULL_TREE, -1);
4893
4894           constructor_index
4895             = convert (bitsizetype,
4896                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
4897         }
4898       else
4899         {
4900           constructor_index = bitsize_zero_node;
4901           constructor_max_index = NULL_TREE;
4902         }
4903
4904       constructor_unfilled_index = constructor_index;
4905     }
4906   else if (TREE_CODE (constructor_type) == VECTOR_TYPE)
4907     {
4908       /* Vectors are like simple fixed-size arrays.  */
4909       constructor_max_index =
4910         build_int_cst (NULL_TREE, TYPE_VECTOR_SUBPARTS (constructor_type) - 1);
4911       constructor_index = convert (bitsizetype, bitsize_zero_node);
4912       constructor_unfilled_index = constructor_index;
4913     }
4914   else
4915     {
4916       /* Handle the case of int x = {5}; */
4917       constructor_fields = constructor_type;
4918       constructor_unfilled_fields = constructor_type;
4919     }
4920 }
4921 \f
4922 /* Push down into a subobject, for initialization.
4923    If this is for an explicit set of braces, IMPLICIT is 0.
4924    If it is because the next element belongs at a lower level,
4925    IMPLICIT is 1 (or 2 if the push is because of designator list).  */
4926
4927 void
4928 push_init_level (int implicit)
4929 {
4930   struct constructor_stack *p;
4931   tree value = NULL_TREE;
4932
4933   /* If we've exhausted any levels that didn't have braces,
4934      pop them now.  If implicit == 1, this will have been done in
4935      process_init_element; do not repeat it here because in the case
4936      of excess initializers for an empty aggregate this leads to an
4937      infinite cycle of popping a level and immediately recreating
4938      it.  */
4939   if (implicit != 1)
4940     {
4941       while (constructor_stack->implicit)
4942         {
4943           if ((TREE_CODE (constructor_type) == RECORD_TYPE
4944                || TREE_CODE (constructor_type) == UNION_TYPE)
4945               && constructor_fields == 0)
4946             process_init_element (pop_init_level (1));
4947           else if (TREE_CODE (constructor_type) == ARRAY_TYPE
4948                    && constructor_max_index
4949                    && tree_int_cst_lt (constructor_max_index,
4950                                        constructor_index))
4951             process_init_element (pop_init_level (1));
4952           else
4953             break;
4954         }
4955     }
4956
4957   /* Unless this is an explicit brace, we need to preserve previous
4958      content if any.  */
4959   if (implicit)
4960     {
4961       if ((TREE_CODE (constructor_type) == RECORD_TYPE
4962            || TREE_CODE (constructor_type) == UNION_TYPE)
4963           && constructor_fields)
4964         value = find_init_member (constructor_fields);
4965       else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
4966         value = find_init_member (constructor_index);
4967     }
4968
4969   p = XNEW (struct constructor_stack);
4970   p->type = constructor_type;
4971   p->fields = constructor_fields;
4972   p->index = constructor_index;
4973   p->max_index = constructor_max_index;
4974   p->unfilled_index = constructor_unfilled_index;
4975   p->unfilled_fields = constructor_unfilled_fields;
4976   p->bit_index = constructor_bit_index;
4977   p->elements = constructor_elements;
4978   p->constant = constructor_constant;
4979   p->simple = constructor_simple;
4980   p->erroneous = constructor_erroneous;
4981   p->pending_elts = constructor_pending_elts;
4982   p->depth = constructor_depth;
4983   p->replacement_value.value = 0;
4984   p->replacement_value.original_code = ERROR_MARK;
4985   p->implicit = implicit;
4986   p->outer = 0;
4987   p->incremental = constructor_incremental;
4988   p->designated = constructor_designated;
4989   p->next = constructor_stack;
4990   p->range_stack = 0;
4991   constructor_stack = p;
4992
4993   constructor_constant = 1;
4994   constructor_simple = 1;
4995   constructor_depth = SPELLING_DEPTH ();
4996   constructor_elements = 0;
4997   constructor_incremental = 1;
4998   constructor_designated = 0;
4999   constructor_pending_elts = 0;
5000   if (!implicit)
5001     {
5002       p->range_stack = constructor_range_stack;
5003       constructor_range_stack = 0;
5004       designator_depth = 0;
5005       designator_errorneous = 0;
5006     }
5007
5008   /* Don't die if an entire brace-pair level is superfluous
5009      in the containing level.  */
5010   if (constructor_type == 0)
5011     ;
5012   else if (TREE_CODE (constructor_type) == RECORD_TYPE
5013            || TREE_CODE (constructor_type) == UNION_TYPE)
5014     {
5015       /* Don't die if there are extra init elts at the end.  */
5016       if (constructor_fields == 0)
5017         constructor_type = 0;
5018       else
5019         {
5020           constructor_type = TREE_TYPE (constructor_fields);
5021           push_member_name (constructor_fields);
5022           constructor_depth++;
5023         }
5024     }
5025   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5026     {
5027       constructor_type = TREE_TYPE (constructor_type);
5028       push_array_bounds (tree_low_cst (constructor_index, 0));
5029       constructor_depth++;
5030     }
5031
5032   if (constructor_type == 0)
5033     {
5034       error_init ("extra brace group at end of initializer");
5035       constructor_fields = 0;
5036       constructor_unfilled_fields = 0;
5037       return;
5038     }
5039
5040   if (value && TREE_CODE (value) == CONSTRUCTOR)
5041     {
5042       constructor_constant = TREE_CONSTANT (value);
5043       constructor_simple = TREE_STATIC (value);
5044       constructor_elements = CONSTRUCTOR_ELTS (value);
5045       if (!VEC_empty (constructor_elt, constructor_elements)
5046           && (TREE_CODE (constructor_type) == RECORD_TYPE
5047               || TREE_CODE (constructor_type) == ARRAY_TYPE))
5048         set_nonincremental_init ();
5049     }
5050
5051   if (implicit == 1 && warn_missing_braces && !missing_braces_mentioned)
5052     {
5053       missing_braces_mentioned = 1;
5054       warning_init ("missing braces around initializer");
5055     }
5056
5057   if (TREE_CODE (constructor_type) == RECORD_TYPE
5058            || TREE_CODE (constructor_type) == UNION_TYPE)
5059     {
5060       constructor_fields = TYPE_FIELDS (constructor_type);
5061       /* Skip any nameless bit fields at the beginning.  */
5062       while (constructor_fields != 0 && DECL_C_BIT_FIELD (constructor_fields)
5063              && DECL_NAME (constructor_fields) == 0)
5064         constructor_fields = TREE_CHAIN (constructor_fields);
5065
5066       constructor_unfilled_fields = constructor_fields;
5067       constructor_bit_index = bitsize_zero_node;
5068     }
5069   else if (TREE_CODE (constructor_type) == VECTOR_TYPE)
5070     {
5071       /* Vectors are like simple fixed-size arrays.  */
5072       constructor_max_index =
5073         build_int_cst (NULL_TREE, TYPE_VECTOR_SUBPARTS (constructor_type) - 1);
5074       constructor_index = convert (bitsizetype, integer_zero_node);
5075       constructor_unfilled_index = constructor_index;
5076     }
5077   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5078     {
5079       if (TYPE_DOMAIN (constructor_type))
5080         {
5081           constructor_max_index
5082             = TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type));
5083
5084           /* Detect non-empty initializations of zero-length arrays.  */
5085           if (constructor_max_index == NULL_TREE
5086               && TYPE_SIZE (constructor_type))
5087             constructor_max_index = build_int_cst (NULL_TREE, -1);
5088
5089           /* constructor_max_index needs to be an INTEGER_CST.  Attempts
5090              to initialize VLAs will cause a proper error; avoid tree
5091              checking errors as well by setting a safe value.  */
5092           if (constructor_max_index
5093               && TREE_CODE (constructor_max_index) != INTEGER_CST)
5094             constructor_max_index = build_int_cst (NULL_TREE, -1);
5095
5096           constructor_index
5097             = convert (bitsizetype,
5098                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
5099         }
5100       else
5101         constructor_index = bitsize_zero_node;
5102
5103       constructor_unfilled_index = constructor_index;
5104       if (value && TREE_CODE (value) == STRING_CST)
5105         {
5106           /* We need to split the char/wchar array into individual
5107              characters, so that we don't have to special case it
5108              everywhere.  */
5109           set_nonincremental_init_from_string (value);
5110         }
5111     }
5112   else
5113     {
5114       if (constructor_type != error_mark_node)
5115         warning_init ("braces around scalar initializer");
5116       constructor_fields = constructor_type;
5117       constructor_unfilled_fields = constructor_type;
5118     }
5119 }
5120
5121 /* At the end of an implicit or explicit brace level,
5122    finish up that level of constructor.  If a single expression
5123    with redundant braces initialized that level, return the
5124    c_expr structure for that expression.  Otherwise, the original_code
5125    element is set to ERROR_MARK.
5126    If we were outputting the elements as they are read, return 0 as the value
5127    from inner levels (process_init_element ignores that),
5128    but return error_mark_node as the value from the outermost level
5129    (that's what we want to put in DECL_INITIAL).
5130    Otherwise, return a CONSTRUCTOR expression as the value.  */
5131
5132 struct c_expr
5133 pop_init_level (int implicit)
5134 {
5135   struct constructor_stack *p;
5136   struct c_expr ret;
5137   ret.value = 0;
5138   ret.original_code = ERROR_MARK;
5139
5140   if (implicit == 0)
5141     {
5142       /* When we come to an explicit close brace,
5143          pop any inner levels that didn't have explicit braces.  */
5144       while (constructor_stack->implicit)
5145         process_init_element (pop_init_level (1));
5146
5147       gcc_assert (!constructor_range_stack);
5148     }
5149
5150   /* Now output all pending elements.  */
5151   constructor_incremental = 1;
5152   output_pending_init_elements (1);
5153
5154   p = constructor_stack;
5155
5156   /* Error for initializing a flexible array member, or a zero-length
5157      array member in an inappropriate context.  */
5158   if (constructor_type && constructor_fields
5159       && TREE_CODE (constructor_type) == ARRAY_TYPE
5160       && TYPE_DOMAIN (constructor_type)
5161       && !TYPE_MAX_VALUE (TYPE_DOMAIN (constructor_type)))
5162     {
5163       /* Silently discard empty initializations.  The parser will
5164          already have pedwarned for empty brackets.  */
5165       if (integer_zerop (constructor_unfilled_index))
5166         constructor_type = NULL_TREE;
5167       else
5168         {
5169           gcc_assert (!TYPE_SIZE (constructor_type));
5170
5171           if (constructor_depth > 2)
5172             error_init ("initialization of flexible array member in a nested context");
5173           else if (pedantic)
5174             pedwarn_init ("initialization of a flexible array member");
5175
5176           /* We have already issued an error message for the existence
5177              of a flexible array member not at the end of the structure.
5178              Discard the initializer so that we do not die later.  */
5179           if (TREE_CHAIN (constructor_fields) != NULL_TREE)
5180             constructor_type = NULL_TREE;
5181         }
5182     }
5183
5184   /* Warn when some struct elements are implicitly initialized to zero.  */
5185   if (warn_missing_field_initializers
5186       && constructor_type
5187       && TREE_CODE (constructor_type) == RECORD_TYPE
5188       && constructor_unfilled_fields)
5189     {
5190         /* Do not warn for flexible array members or zero-length arrays.  */
5191         while (constructor_unfilled_fields
5192                && (!DECL_SIZE (constructor_unfilled_fields)
5193                    || integer_zerop (DECL_SIZE (constructor_unfilled_fields))))
5194           constructor_unfilled_fields = TREE_CHAIN (constructor_unfilled_fields);
5195
5196         /* Do not warn if this level of the initializer uses member
5197            designators; it is likely to be deliberate.  */
5198         if (constructor_unfilled_fields && !constructor_designated)
5199           {
5200             push_member_name (constructor_unfilled_fields);
5201             warning_init ("missing initializer");
5202             RESTORE_SPELLING_DEPTH (constructor_depth);
5203           }
5204     }
5205
5206   /* Pad out the end of the structure.  */
5207   if (p->replacement_value.value)
5208     /* If this closes a superfluous brace pair,
5209        just pass out the element between them.  */
5210     ret = p->replacement_value;
5211   else if (constructor_type == 0)
5212     ;
5213   else if (TREE_CODE (constructor_type) != RECORD_TYPE
5214            && TREE_CODE (constructor_type) != UNION_TYPE
5215            && TREE_CODE (constructor_type) != ARRAY_TYPE
5216            && TREE_CODE (constructor_type) != VECTOR_TYPE)
5217     {
5218       /* A nonincremental scalar initializer--just return
5219          the element, after verifying there is just one.  */
5220       if (VEC_empty (constructor_elt,constructor_elements))
5221         {
5222           if (!constructor_erroneous)
5223             error_init ("empty scalar initializer");
5224           ret.value = error_mark_node;
5225         }
5226       else if (VEC_length (constructor_elt,constructor_elements) != 1)
5227         {
5228           error_init ("extra elements in scalar initializer");
5229           ret.value = VEC_index (constructor_elt,constructor_elements,0)->value;
5230         }
5231       else
5232         ret.value = VEC_index (constructor_elt,constructor_elements,0)->value;
5233     }
5234   else
5235     {
5236       if (constructor_erroneous)
5237         ret.value = error_mark_node;
5238       else
5239         {
5240           ret.value = build_constructor (constructor_type,
5241                                          constructor_elements);
5242           if (constructor_constant)
5243             TREE_CONSTANT (ret.value) = TREE_INVARIANT (ret.value) = 1;
5244           if (constructor_constant && constructor_simple)
5245             TREE_STATIC (ret.value) = 1;
5246         }
5247     }
5248
5249   constructor_type = p->type;
5250   constructor_fields = p->fields;
5251   constructor_index = p->index;
5252   constructor_max_index = p->max_index;
5253   constructor_unfilled_index = p->unfilled_index;
5254   constructor_unfilled_fields = p->unfilled_fields;
5255   constructor_bit_index = p->bit_index;
5256   constructor_elements = p->elements;
5257   constructor_constant = p->constant;
5258   constructor_simple = p->simple;
5259   constructor_erroneous = p->erroneous;
5260   constructor_incremental = p->incremental;
5261   constructor_designated = p->designated;
5262   constructor_pending_elts = p->pending_elts;
5263   constructor_depth = p->depth;
5264   if (!p->implicit)
5265     constructor_range_stack = p->range_stack;
5266   RESTORE_SPELLING_DEPTH (constructor_depth);
5267
5268   constructor_stack = p->next;
5269   free (p);
5270
5271   if (ret.value == 0)
5272     {
5273       if (constructor_stack == 0)
5274         {
5275           ret.value = error_mark_node;
5276           return ret;
5277         }
5278       return ret;
5279     }
5280   return ret;
5281 }
5282
5283 /* Common handling for both array range and field name designators.
5284    ARRAY argument is nonzero for array ranges.  Returns zero for success.  */
5285
5286 static int
5287 set_designator (int array)
5288 {
5289   tree subtype;
5290   enum tree_code subcode;
5291
5292   /* Don't die if an entire brace-pair level is superfluous
5293      in the containing level.  */
5294   if (constructor_type == 0)
5295     return 1;
5296
5297   /* If there were errors in this designator list already, bail out
5298      silently.  */
5299   if (designator_errorneous)
5300     return 1;
5301
5302   if (!designator_depth)
5303     {
5304       gcc_assert (!constructor_range_stack);
5305
5306       /* Designator list starts at the level of closest explicit
5307          braces.  */
5308       while (constructor_stack->implicit)
5309         process_init_element (pop_init_level (1));
5310       constructor_designated = 1;
5311       return 0;
5312     }
5313
5314   switch (TREE_CODE (constructor_type))
5315     {
5316     case  RECORD_TYPE:
5317     case  UNION_TYPE:
5318       subtype = TREE_TYPE (constructor_fields);
5319       if (subtype != error_mark_node)
5320         subtype = TYPE_MAIN_VARIANT (subtype);
5321       break;
5322     case ARRAY_TYPE:
5323       subtype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
5324       break;
5325     default:
5326       gcc_unreachable ();
5327     }
5328
5329   subcode = TREE_CODE (subtype);
5330   if (array && subcode != ARRAY_TYPE)
5331     {
5332       error_init ("array index in non-array initializer");
5333       return 1;
5334     }
5335   else if (!array && subcode != RECORD_TYPE && subcode != UNION_TYPE)
5336     {
5337       error_init ("field name not in record or union initializer");
5338       return 1;
5339     }
5340
5341   constructor_designated = 1;
5342   push_init_level (2);
5343   return 0;
5344 }
5345
5346 /* If there are range designators in designator list, push a new designator
5347    to constructor_range_stack.  RANGE_END is end of such stack range or
5348    NULL_TREE if there is no range designator at this level.  */
5349
5350 static void
5351 push_range_stack (tree range_end)
5352 {
5353   struct constructor_range_stack *p;
5354
5355   p = GGC_NEW (struct constructor_range_stack);
5356   p->prev = constructor_range_stack;
5357   p->next = 0;
5358   p->fields = constructor_fields;
5359   p->range_start = constructor_index;
5360   p->index = constructor_index;
5361   p->stack = constructor_stack;
5362   p->range_end = range_end;
5363   if (constructor_range_stack)
5364     constructor_range_stack->next = p;
5365   constructor_range_stack = p;
5366 }
5367
5368 /* Within an array initializer, specify the next index to be initialized.
5369    FIRST is that index.  If LAST is nonzero, then initialize a range
5370    of indices, running from FIRST through LAST.  */
5371
5372 void
5373 set_init_index (tree first, tree last)
5374 {
5375   if (set_designator (1))
5376     return;
5377
5378   designator_errorneous = 1;
5379
5380   if (!INTEGRAL_TYPE_P (TREE_TYPE (first))
5381       || (last && !INTEGRAL_TYPE_P (TREE_TYPE (last))))
5382     {
5383       error_init ("array index in initializer not of integer type");
5384       return;
5385     }
5386
5387   if (TREE_CODE (first) != INTEGER_CST)
5388     error_init ("nonconstant array index in initializer");
5389   else if (last != 0 && TREE_CODE (last) != INTEGER_CST)
5390     error_init ("nonconstant array index in initializer");
5391   else if (TREE_CODE (constructor_type) != ARRAY_TYPE)
5392     error_init ("array index in non-array initializer");
5393   else if (tree_int_cst_sgn (first) == -1)
5394     error_init ("array index in initializer exceeds array bounds");
5395   else if (constructor_max_index
5396            && tree_int_cst_lt (constructor_max_index, first))
5397     error_init ("array index in initializer exceeds array bounds");
5398   else
5399     {
5400       constructor_index = convert (bitsizetype, first);
5401
5402       if (last)
5403         {
5404           if (tree_int_cst_equal (first, last))
5405             last = 0;
5406           else if (tree_int_cst_lt (last, first))
5407             {
5408               error_init ("empty index range in initializer");
5409               last = 0;
5410             }
5411           else
5412             {
5413               last = convert (bitsizetype, last);
5414               if (constructor_max_index != 0
5415                   && tree_int_cst_lt (constructor_max_index, last))
5416                 {
5417                   error_init ("array index range in initializer exceeds array bounds");
5418                   last = 0;
5419                 }
5420             }
5421         }
5422
5423       designator_depth++;
5424       designator_errorneous = 0;
5425       if (constructor_range_stack || last)
5426         push_range_stack (last);
5427     }
5428 }
5429
5430 /* Within a struct initializer, specify the next field to be initialized.  */
5431
5432 void
5433 set_init_label (tree fieldname)
5434 {
5435   tree tail;
5436
5437   if (set_designator (0))
5438     return;
5439
5440   designator_errorneous = 1;
5441
5442   if (TREE_CODE (constructor_type) != RECORD_TYPE
5443       && TREE_CODE (constructor_type) != UNION_TYPE)
5444     {
5445       error_init ("field name not in record or union initializer");
5446       return;
5447     }
5448
5449   for (tail = TYPE_FIELDS (constructor_type); tail;
5450        tail = TREE_CHAIN (tail))
5451     {
5452       if (DECL_NAME (tail) == fieldname)
5453         break;
5454     }
5455
5456   if (tail == 0)
5457     error ("unknown field %qE specified in initializer", fieldname);
5458   else
5459     {
5460       constructor_fields = tail;
5461       designator_depth++;
5462       designator_errorneous = 0;
5463       if (constructor_range_stack)
5464         push_range_stack (NULL_TREE);
5465     }
5466 }
5467 \f
5468 /* Add a new initializer to the tree of pending initializers.  PURPOSE
5469    identifies the initializer, either array index or field in a structure.
5470    VALUE is the value of that index or field.  */
5471
5472 static void
5473 add_pending_init (tree purpose, tree value)
5474 {
5475   struct init_node *p, **q, *r;
5476
5477   q = &constructor_pending_elts;
5478   p = 0;
5479
5480   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5481     {
5482       while (*q != 0)
5483         {
5484           p = *q;
5485           if (tree_int_cst_lt (purpose, p->purpose))
5486             q = &p->left;
5487           else if (tree_int_cst_lt (p->purpose, purpose))
5488             q = &p->right;
5489           else
5490             {
5491               if (TREE_SIDE_EFFECTS (p->value))
5492                 warning_init ("initialized field with side-effects overwritten");
5493               p->value = value;
5494               return;
5495             }
5496         }
5497     }
5498   else
5499     {
5500       tree bitpos;
5501
5502       bitpos = bit_position (purpose);
5503       while (*q != NULL)
5504         {
5505           p = *q;
5506           if (tree_int_cst_lt (bitpos, bit_position (p->purpose)))
5507             q = &p->left;
5508           else if (p->purpose != purpose)
5509             q = &p->right;
5510           else
5511             {
5512               if (TREE_SIDE_EFFECTS (p->value))
5513                 warning_init ("initialized field with side-effects overwritten");
5514               p->value = value;
5515               return;
5516             }
5517         }
5518     }
5519
5520   r = GGC_NEW (struct init_node);
5521   r->purpose = purpose;
5522   r->value = value;
5523
5524   *q = r;
5525   r->parent = p;
5526   r->left = 0;
5527   r->right = 0;
5528   r->balance = 0;
5529
5530   while (p)
5531     {
5532       struct init_node *s;
5533
5534       if (r == p->left)
5535         {
5536           if (p->balance == 0)
5537             p->balance = -1;
5538           else if (p->balance < 0)
5539             {
5540               if (r->balance < 0)
5541                 {
5542                   /* L rotation.  */
5543                   p->left = r->right;
5544                   if (p->left)
5545                     p->left->parent = p;
5546                   r->right = p;
5547
5548                   p->balance = 0;
5549                   r->balance = 0;
5550
5551                   s = p->parent;
5552                   p->parent = r;
5553                   r->parent = s;
5554                   if (s)
5555                     {
5556                       if (s->left == p)
5557                         s->left = r;
5558                       else
5559                         s->right = r;
5560                     }
5561                   else
5562                     constructor_pending_elts = r;
5563                 }
5564               else
5565                 {
5566                   /* LR rotation.  */
5567                   struct init_node *t = r->right;
5568
5569                   r->right = t->left;
5570                   if (r->right)
5571                     r->right->parent = r;
5572                   t->left = r;
5573
5574                   p->left = t->right;
5575                   if (p->left)
5576                     p->left->parent = p;
5577                   t->right = p;
5578
5579                   p->balance = t->balance < 0;
5580                   r->balance = -(t->balance > 0);
5581                   t->balance = 0;
5582
5583                   s = p->parent;
5584                   p->parent = t;
5585                   r->parent = t;
5586                   t->parent = s;
5587                   if (s)
5588                     {
5589                       if (s->left == p)
5590                         s->left = t;
5591                       else
5592                         s->right = t;
5593                     }
5594                   else
5595                     constructor_pending_elts = t;
5596                 }
5597               break;
5598             }
5599           else
5600             {
5601               /* p->balance == +1; growth of left side balances the node.  */
5602               p->balance = 0;
5603               break;
5604             }
5605         }
5606       else /* r == p->right */
5607         {
5608           if (p->balance == 0)
5609             /* Growth propagation from right side.  */
5610             p->balance++;
5611           else if (p->balance > 0)
5612             {
5613               if (r->balance > 0)
5614                 {
5615                   /* R rotation.  */
5616                   p->right = r->left;
5617                   if (p->right)
5618                     p->right->parent = p;
5619                   r->left = p;
5620
5621                   p->balance = 0;
5622                   r->balance = 0;
5623
5624                   s = p->parent;
5625                   p->parent = r;
5626                   r->parent = s;
5627                   if (s)
5628                     {
5629                       if (s->left == p)
5630                         s->left = r;
5631                       else
5632                         s->right = r;
5633                     }
5634                   else
5635                     constructor_pending_elts = r;
5636                 }
5637               else /* r->balance == -1 */
5638                 {
5639                   /* RL rotation */
5640                   struct init_node *t = r->left;
5641
5642                   r->left = t->right;
5643                   if (r->left)
5644                     r->left->parent = r;
5645                   t->right = r;
5646
5647                   p->right = t->left;
5648                   if (p->right)
5649                     p->right->parent = p;
5650                   t->left = p;
5651
5652                   r->balance = (t->balance < 0);
5653                   p->balance = -(t->balance > 0);
5654                   t->balance = 0;
5655
5656                   s = p->parent;
5657                   p->parent = t;
5658                   r->parent = t;
5659                   t->parent = s;
5660                   if (s)
5661                     {
5662                       if (s->left == p)
5663                         s->left = t;
5664                       else
5665                         s->right = t;
5666                     }
5667                   else
5668                     constructor_pending_elts = t;
5669                 }
5670               break;
5671             }
5672           else
5673             {
5674               /* p->balance == -1; growth of right side balances the node.  */
5675               p->balance = 0;
5676               break;
5677             }
5678         }
5679
5680       r = p;
5681       p = p->parent;
5682     }
5683 }
5684
5685 /* Build AVL tree from a sorted chain.  */
5686
5687 static void
5688 set_nonincremental_init (void)
5689 {
5690   unsigned HOST_WIDE_INT ix;
5691   tree index, value;
5692
5693   if (TREE_CODE (constructor_type) != RECORD_TYPE
5694       && TREE_CODE (constructor_type) != ARRAY_TYPE)
5695     return;
5696
5697   FOR_EACH_CONSTRUCTOR_ELT (constructor_elements, ix, index, value)
5698     add_pending_init (index, value);
5699   constructor_elements = 0;
5700   if (TREE_CODE (constructor_type) == RECORD_TYPE)
5701     {
5702       constructor_unfilled_fields = TYPE_FIELDS (constructor_type);
5703       /* Skip any nameless bit fields at the beginning.  */
5704       while (constructor_unfilled_fields != 0
5705              && DECL_C_BIT_FIELD (constructor_unfilled_fields)
5706              && DECL_NAME (constructor_unfilled_fields) == 0)
5707         constructor_unfilled_fields = TREE_CHAIN (constructor_unfilled_fields);
5708
5709     }
5710   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5711     {
5712       if (TYPE_DOMAIN (constructor_type))
5713         constructor_unfilled_index
5714             = convert (bitsizetype,
5715                        TYPE_MIN_VALUE (TYPE_DOMAIN (constructor_type)));
5716       else
5717         constructor_unfilled_index = bitsize_zero_node;
5718     }
5719   constructor_incremental = 0;
5720 }
5721
5722 /* Build AVL tree from a string constant.  */
5723
5724 static void
5725 set_nonincremental_init_from_string (tree str)
5726 {
5727   tree value, purpose, type;
5728   HOST_WIDE_INT val[2];
5729   const char *p, *end;
5730   int byte, wchar_bytes, charwidth, bitpos;
5731
5732   gcc_assert (TREE_CODE (constructor_type) == ARRAY_TYPE);
5733
5734   if (TYPE_PRECISION (TREE_TYPE (TREE_TYPE (str)))
5735       == TYPE_PRECISION (char_type_node))
5736     wchar_bytes = 1;
5737   else
5738     {
5739       gcc_assert (TYPE_PRECISION (TREE_TYPE (TREE_TYPE (str)))
5740                   == TYPE_PRECISION (wchar_type_node));
5741       wchar_bytes = TYPE_PRECISION (wchar_type_node) / BITS_PER_UNIT;
5742     }
5743   charwidth = TYPE_PRECISION (char_type_node);
5744   type = TREE_TYPE (constructor_type);
5745   p = TREE_STRING_POINTER (str);
5746   end = p + TREE_STRING_LENGTH (str);
5747
5748   for (purpose = bitsize_zero_node;
5749        p < end && !tree_int_cst_lt (constructor_max_index, purpose);
5750        purpose = size_binop (PLUS_EXPR, purpose, bitsize_one_node))
5751     {
5752       if (wchar_bytes == 1)
5753         {
5754           val[1] = (unsigned char) *p++;
5755           val[0] = 0;
5756         }
5757       else
5758         {
5759           val[0] = 0;
5760           val[1] = 0;
5761           for (byte = 0; byte < wchar_bytes; byte++)
5762             {
5763               if (BYTES_BIG_ENDIAN)
5764                 bitpos = (wchar_bytes - byte - 1) * charwidth;
5765               else
5766                 bitpos = byte * charwidth;
5767               val[bitpos < HOST_BITS_PER_WIDE_INT]
5768                 |= ((unsigned HOST_WIDE_INT) ((unsigned char) *p++))
5769                    << (bitpos % HOST_BITS_PER_WIDE_INT);
5770             }
5771         }
5772
5773       if (!TYPE_UNSIGNED (type))
5774         {
5775           bitpos = ((wchar_bytes - 1) * charwidth) + HOST_BITS_PER_CHAR;
5776           if (bitpos < HOST_BITS_PER_WIDE_INT)
5777             {
5778               if (val[1] & (((HOST_WIDE_INT) 1) << (bitpos - 1)))
5779                 {
5780                   val[1] |= ((HOST_WIDE_INT) -1) << bitpos;
5781                   val[0] = -1;
5782                 }
5783             }
5784           else if (bitpos == HOST_BITS_PER_WIDE_INT)
5785             {
5786               if (val[1] < 0)
5787                 val[0] = -1;
5788             }
5789           else if (val[0] & (((HOST_WIDE_INT) 1)
5790                              << (bitpos - 1 - HOST_BITS_PER_WIDE_INT)))
5791             val[0] |= ((HOST_WIDE_INT) -1)
5792                       << (bitpos - HOST_BITS_PER_WIDE_INT);
5793         }
5794
5795       value = build_int_cst_wide (type, val[1], val[0]);
5796       add_pending_init (purpose, value);
5797     }
5798
5799   constructor_incremental = 0;
5800 }
5801
5802 /* Return value of FIELD in pending initializer or zero if the field was
5803    not initialized yet.  */
5804
5805 static tree
5806 find_init_member (tree field)
5807 {
5808   struct init_node *p;
5809
5810   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
5811     {
5812       if (constructor_incremental
5813           && tree_int_cst_lt (field, constructor_unfilled_index))
5814         set_nonincremental_init ();
5815
5816       p = constructor_pending_elts;
5817       while (p)
5818         {
5819           if (tree_int_cst_lt (field, p->purpose))
5820             p = p->left;
5821           else if (tree_int_cst_lt (p->purpose, field))
5822             p = p->right;
5823           else
5824             return p->value;
5825         }
5826     }
5827   else if (TREE_CODE (constructor_type) == RECORD_TYPE)
5828     {
5829       tree bitpos = bit_position (field);
5830
5831       if (constructor_incremental
5832           && (!constructor_unfilled_fields
5833               || tree_int_cst_lt (bitpos,
5834                                   bit_position (constructor_unfilled_fields))))
5835         set_nonincremental_init ();
5836
5837       p = constructor_pending_elts;
5838       while (p)
5839         {
5840           if (field == p->purpose)
5841             return p->value;
5842           else if (tree_int_cst_lt (bitpos, bit_position (p->purpose)))
5843             p = p->left;
5844           else
5845             p = p->right;
5846         }
5847     }
5848   else if (TREE_CODE (constructor_type) == UNION_TYPE)
5849     {
5850       if (!VEC_empty (constructor_elt, constructor_elements)
5851           && (VEC_last (constructor_elt, constructor_elements)->index
5852               == field))
5853         return VEC_last (constructor_elt, constructor_elements)->value;
5854     }
5855   return 0;
5856 }
5857
5858 /* "Output" the next constructor element.
5859    At top level, really output it to assembler code now.
5860    Otherwise, collect it in a list from which we will make a CONSTRUCTOR.
5861    TYPE is the data type that the containing data type wants here.
5862    FIELD is the field (a FIELD_DECL) or the index that this element fills.
5863    If VALUE is a string constant, STRICT_STRING is true if it is
5864    unparenthesized or we should not warn here for it being parenthesized.
5865    For other types of VALUE, STRICT_STRING is not used.
5866
5867    PENDING if non-nil means output pending elements that belong
5868    right after this element.  (PENDING is normally 1;
5869    it is 0 while outputting pending elements, to avoid recursion.)  */
5870
5871 static void
5872 output_init_element (tree value, bool strict_string, tree type, tree field,
5873                      int pending)
5874 {
5875   constructor_elt *celt;
5876
5877   if (type == error_mark_node || value == error_mark_node)
5878     {
5879       constructor_erroneous = 1;
5880       return;
5881     }
5882   if (TREE_CODE (TREE_TYPE (value)) == ARRAY_TYPE
5883       && (TREE_CODE (value) == STRING_CST
5884           || TREE_CODE (value) == COMPOUND_LITERAL_EXPR)
5885       && !(TREE_CODE (value) == STRING_CST
5886            && TREE_CODE (type) == ARRAY_TYPE
5887            && INTEGRAL_TYPE_P (TREE_TYPE (type)))
5888       && !comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (value)),
5889                      TYPE_MAIN_VARIANT (type)))
5890     value = array_to_pointer_conversion (value);
5891
5892   if (TREE_CODE (value) == COMPOUND_LITERAL_EXPR
5893       && require_constant_value && !flag_isoc99 && pending)
5894     {
5895       /* As an extension, allow initializing objects with static storage
5896          duration with compound literals (which are then treated just as
5897          the brace enclosed list they contain).  */
5898       tree decl = COMPOUND_LITERAL_EXPR_DECL (value);
5899       value = DECL_INITIAL (decl);
5900     }
5901
5902   if (value == error_mark_node)
5903     constructor_erroneous = 1;
5904   else if (!TREE_CONSTANT (value))
5905     constructor_constant = 0;
5906   else if (!initializer_constant_valid_p (value, TREE_TYPE (value))
5907            || ((TREE_CODE (constructor_type) == RECORD_TYPE
5908                 || TREE_CODE (constructor_type) == UNION_TYPE)
5909                && DECL_C_BIT_FIELD (field)
5910                && TREE_CODE (value) != INTEGER_CST))
5911     constructor_simple = 0;
5912
5913   if (!initializer_constant_valid_p (value, TREE_TYPE (value)))
5914     {
5915       if (require_constant_value)
5916         {
5917           error_init ("initializer element is not constant");
5918           value = error_mark_node;
5919         }
5920       else if (require_constant_elements)
5921         pedwarn ("initializer element is not computable at load time");
5922     }
5923
5924   /* If this field is empty (and not at the end of structure),
5925      don't do anything other than checking the initializer.  */
5926   if (field
5927       && (TREE_TYPE (field) == error_mark_node
5928           || (COMPLETE_TYPE_P (TREE_TYPE (field))
5929               && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))
5930               && (TREE_CODE (constructor_type) == ARRAY_TYPE
5931                   || TREE_CHAIN (field)))))
5932     return;
5933
5934   value = digest_init (type, value, strict_string, require_constant_value);
5935   if (value == error_mark_node)
5936     {
5937       constructor_erroneous = 1;
5938       return;
5939     }
5940
5941   /* If this element doesn't come next in sequence,
5942      put it on constructor_pending_elts.  */
5943   if (TREE_CODE (constructor_type) == ARRAY_TYPE
5944       && (!constructor_incremental
5945           || !tree_int_cst_equal (field, constructor_unfilled_index)))
5946     {
5947       if (constructor_incremental
5948           && tree_int_cst_lt (field, constructor_unfilled_index))
5949         set_nonincremental_init ();
5950
5951       add_pending_init (field, value);
5952       return;
5953     }
5954   else if (TREE_CODE (constructor_type) == RECORD_TYPE
5955            && (!constructor_incremental
5956                || field != constructor_unfilled_fields))
5957     {
5958       /* We do this for records but not for unions.  In a union,
5959          no matter which field is specified, it can be initialized
5960          right away since it starts at the beginning of the union.  */
5961       if (constructor_incremental)
5962         {
5963           if (!constructor_unfilled_fields)
5964             set_nonincremental_init ();
5965           else
5966             {
5967               tree bitpos, unfillpos;
5968
5969               bitpos = bit_position (field);
5970               unfillpos = bit_position (constructor_unfilled_fields);
5971
5972               if (tree_int_cst_lt (bitpos, unfillpos))
5973                 set_nonincremental_init ();
5974             }
5975         }
5976
5977       add_pending_init (field, value);
5978       return;
5979     }
5980   else if (TREE_CODE (constructor_type) == UNION_TYPE
5981            && !VEC_empty (constructor_elt, constructor_elements))
5982     {
5983       if (TREE_SIDE_EFFECTS (VEC_last (constructor_elt,
5984                                        constructor_elements)->value))
5985         warning_init ("initialized field with side-effects overwritten");
5986
5987       /* We can have just one union field set.  */
5988       constructor_elements = 0;
5989     }
5990
5991   /* Otherwise, output this element either to
5992      constructor_elements or to the assembler file.  */
5993
5994   celt = VEC_safe_push (constructor_elt, gc, constructor_elements, NULL);
5995   celt->index = field;
5996   celt->value = value;
5997
5998   /* Advance the variable that indicates sequential elements output.  */
5999   if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6000     constructor_unfilled_index
6001       = size_binop (PLUS_EXPR, constructor_unfilled_index,
6002                     bitsize_one_node);
6003   else if (TREE_CODE (constructor_type) == RECORD_TYPE)
6004     {
6005       constructor_unfilled_fields
6006         = TREE_CHAIN (constructor_unfilled_fields);
6007
6008       /* Skip any nameless bit fields.  */
6009       while (constructor_unfilled_fields != 0
6010              && DECL_C_BIT_FIELD (constructor_unfilled_fields)
6011              && DECL_NAME (constructor_unfilled_fields) == 0)
6012         constructor_unfilled_fields =
6013           TREE_CHAIN (constructor_unfilled_fields);
6014     }
6015   else if (TREE_CODE (constructor_type) == UNION_TYPE)
6016     constructor_unfilled_fields = 0;
6017
6018   /* Now output any pending elements which have become next.  */
6019   if (pending)
6020     output_pending_init_elements (0);
6021 }
6022
6023 /* Output any pending elements which have become next.
6024    As we output elements, constructor_unfilled_{fields,index}
6025    advances, which may cause other elements to become next;
6026    if so, they too are output.
6027
6028    If ALL is 0, we return when there are
6029    no more pending elements to output now.
6030
6031    If ALL is 1, we output space as necessary so that
6032    we can output all the pending elements.  */
6033
6034 static void
6035 output_pending_init_elements (int all)
6036 {
6037   struct init_node *elt = constructor_pending_elts;
6038   tree next;
6039
6040  retry:
6041
6042   /* Look through the whole pending tree.
6043      If we find an element that should be output now,
6044      output it.  Otherwise, set NEXT to the element
6045      that comes first among those still pending.  */
6046
6047   next = 0;
6048   while (elt)
6049     {
6050       if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6051         {
6052           if (tree_int_cst_equal (elt->purpose,
6053                                   constructor_unfilled_index))
6054             output_init_element (elt->value, true,
6055                                  TREE_TYPE (constructor_type),
6056                                  constructor_unfilled_index, 0);
6057           else if (tree_int_cst_lt (constructor_unfilled_index,
6058                                     elt->purpose))
6059             {
6060               /* Advance to the next smaller node.  */
6061               if (elt->left)
6062                 elt = elt->left;
6063               else
6064                 {
6065                   /* We have reached the smallest node bigger than the
6066                      current unfilled index.  Fill the space first.  */
6067                   next = elt->purpose;
6068                   break;
6069                 }
6070             }
6071           else
6072             {
6073               /* Advance to the next bigger node.  */
6074               if (elt->right)
6075                 elt = elt->right;
6076               else
6077                 {
6078                   /* We have reached the biggest node in a subtree.  Find
6079                      the parent of it, which is the next bigger node.  */
6080                   while (elt->parent && elt->parent->right == elt)
6081                     elt = elt->parent;
6082                   elt = elt->parent;
6083                   if (elt && tree_int_cst_lt (constructor_unfilled_index,
6084                                               elt->purpose))
6085                     {
6086                       next = elt->purpose;
6087                       break;
6088                     }
6089                 }
6090             }
6091         }
6092       else if (TREE_CODE (constructor_type) == RECORD_TYPE
6093                || TREE_CODE (constructor_type) == UNION_TYPE)
6094         {
6095           tree ctor_unfilled_bitpos, elt_bitpos;
6096
6097           /* If the current record is complete we are done.  */
6098           if (constructor_unfilled_fields == 0)
6099             break;
6100
6101           ctor_unfilled_bitpos = bit_position (constructor_unfilled_fields);
6102           elt_bitpos = bit_position (elt->purpose);
6103           /* We can't compare fields here because there might be empty
6104              fields in between.  */
6105           if (tree_int_cst_equal (elt_bitpos, ctor_unfilled_bitpos))
6106             {
6107               constructor_unfilled_fields = elt->purpose;
6108               output_init_element (elt->value, true, TREE_TYPE (elt->purpose),
6109                                    elt->purpose, 0);
6110             }
6111           else if (tree_int_cst_lt (ctor_unfilled_bitpos, elt_bitpos))
6112             {
6113               /* Advance to the next smaller node.  */
6114               if (elt->left)
6115                 elt = elt->left;
6116               else
6117                 {
6118                   /* We have reached the smallest node bigger than the
6119                      current unfilled field.  Fill the space first.  */
6120                   next = elt->purpose;
6121                   break;
6122                 }
6123             }
6124           else
6125             {
6126               /* Advance to the next bigger node.  */
6127               if (elt->right)
6128                 elt = elt->right;
6129               else
6130                 {
6131                   /* We have reached the biggest node in a subtree.  Find
6132                      the parent of it, which is the next bigger node.  */
6133                   while (elt->parent && elt->parent->right == elt)
6134                     elt = elt->parent;
6135                   elt = elt->parent;
6136                   if (elt
6137                       && (tree_int_cst_lt (ctor_unfilled_bitpos,
6138                                            bit_position (elt->purpose))))
6139                     {
6140                       next = elt->purpose;
6141                       break;
6142                     }
6143                 }
6144             }
6145         }
6146     }
6147
6148   /* Ordinarily return, but not if we want to output all
6149      and there are elements left.  */
6150   if (!(all && next != 0))
6151     return;
6152
6153   /* If it's not incremental, just skip over the gap, so that after
6154      jumping to retry we will output the next successive element.  */
6155   if (TREE_CODE (constructor_type) == RECORD_TYPE
6156       || TREE_CODE (constructor_type) == UNION_TYPE)
6157     constructor_unfilled_fields = next;
6158   else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6159     constructor_unfilled_index = next;
6160
6161   /* ELT now points to the node in the pending tree with the next
6162      initializer to output.  */
6163   goto retry;
6164 }
6165 \f
6166 /* Add one non-braced element to the current constructor level.
6167    This adjusts the current position within the constructor's type.
6168    This may also start or terminate implicit levels
6169    to handle a partly-braced initializer.
6170
6171    Once this has found the correct level for the new element,
6172    it calls output_init_element.  */
6173
6174 void
6175 process_init_element (struct c_expr value)
6176 {
6177   tree orig_value = value.value;
6178   int string_flag = orig_value != 0 && TREE_CODE (orig_value) == STRING_CST;
6179   bool strict_string = value.original_code == STRING_CST;
6180
6181   designator_depth = 0;
6182   designator_errorneous = 0;
6183
6184   /* Handle superfluous braces around string cst as in
6185      char x[] = {"foo"}; */
6186   if (string_flag
6187       && constructor_type
6188       && TREE_CODE (constructor_type) == ARRAY_TYPE
6189       && INTEGRAL_TYPE_P (TREE_TYPE (constructor_type))
6190       && integer_zerop (constructor_unfilled_index))
6191     {
6192       if (constructor_stack->replacement_value.value)
6193         error_init ("excess elements in char array initializer");
6194       constructor_stack->replacement_value = value;
6195       return;
6196     }
6197
6198   if (constructor_stack->replacement_value.value != 0)
6199     {
6200       error_init ("excess elements in struct initializer");
6201       return;
6202     }
6203
6204   /* Ignore elements of a brace group if it is entirely superfluous
6205      and has already been diagnosed.  */
6206   if (constructor_type == 0)
6207     return;
6208
6209   /* If we've exhausted any levels that didn't have braces,
6210      pop them now.  */
6211   while (constructor_stack->implicit)
6212     {
6213       if ((TREE_CODE (constructor_type) == RECORD_TYPE
6214            || TREE_CODE (constructor_type) == UNION_TYPE)
6215           && constructor_fields == 0)
6216         process_init_element (pop_init_level (1));
6217       else if (TREE_CODE (constructor_type) == ARRAY_TYPE
6218                && (constructor_max_index == 0
6219                    || tree_int_cst_lt (constructor_max_index,
6220                                        constructor_index)))
6221         process_init_element (pop_init_level (1));
6222       else
6223         break;
6224     }
6225
6226   /* In the case of [LO ... HI] = VALUE, only evaluate VALUE once.  */
6227   if (constructor_range_stack)
6228     {
6229       /* If value is a compound literal and we'll be just using its
6230          content, don't put it into a SAVE_EXPR.  */
6231       if (TREE_CODE (value.value) != COMPOUND_LITERAL_EXPR
6232           || !require_constant_value
6233           || flag_isoc99)
6234         value.value = save_expr (value.value);
6235     }
6236
6237   while (1)
6238     {
6239       if (TREE_CODE (constructor_type) == RECORD_TYPE)
6240         {
6241           tree fieldtype;
6242           enum tree_code fieldcode;
6243
6244           if (constructor_fields == 0)
6245             {
6246               pedwarn_init ("excess elements in struct initializer");
6247               break;
6248             }
6249
6250           fieldtype = TREE_TYPE (constructor_fields);
6251           if (fieldtype != error_mark_node)
6252             fieldtype = TYPE_MAIN_VARIANT (fieldtype);
6253           fieldcode = TREE_CODE (fieldtype);
6254
6255           /* Error for non-static initialization of a flexible array member.  */
6256           if (fieldcode == ARRAY_TYPE
6257               && !require_constant_value
6258               && TYPE_SIZE (fieldtype) == NULL_TREE
6259               && TREE_CHAIN (constructor_fields) == NULL_TREE)
6260             {
6261               error_init ("non-static initialization of a flexible array member");
6262               break;
6263             }
6264
6265           /* Accept a string constant to initialize a subarray.  */
6266           if (value.value != 0
6267               && fieldcode == ARRAY_TYPE
6268               && INTEGRAL_TYPE_P (TREE_TYPE (fieldtype))
6269               && string_flag)
6270             value.value = orig_value;
6271           /* Otherwise, if we have come to a subaggregate,
6272              and we don't have an element of its type, push into it.  */
6273           else if (value.value != 0
6274                    && value.value != error_mark_node
6275                    && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != fieldtype
6276                    && (fieldcode == RECORD_TYPE || fieldcode == ARRAY_TYPE
6277                        || fieldcode == UNION_TYPE))
6278             {
6279               push_init_level (1);
6280               continue;
6281             }
6282
6283           if (value.value)
6284             {
6285               push_member_name (constructor_fields);
6286               output_init_element (value.value, strict_string,
6287                                    fieldtype, constructor_fields, 1);
6288               RESTORE_SPELLING_DEPTH (constructor_depth);
6289             }
6290           else
6291             /* Do the bookkeeping for an element that was
6292                directly output as a constructor.  */
6293             {
6294               /* For a record, keep track of end position of last field.  */
6295               if (DECL_SIZE (constructor_fields))
6296                 constructor_bit_index
6297                   = size_binop (PLUS_EXPR,
6298                                 bit_position (constructor_fields),
6299                                 DECL_SIZE (constructor_fields));
6300
6301               /* If the current field was the first one not yet written out,
6302                  it isn't now, so update.  */
6303               if (constructor_unfilled_fields == constructor_fields)
6304                 {
6305                   constructor_unfilled_fields = TREE_CHAIN (constructor_fields);
6306                   /* Skip any nameless bit fields.  */
6307                   while (constructor_unfilled_fields != 0
6308                          && DECL_C_BIT_FIELD (constructor_unfilled_fields)
6309                          && DECL_NAME (constructor_unfilled_fields) == 0)
6310                     constructor_unfilled_fields =
6311                       TREE_CHAIN (constructor_unfilled_fields);
6312                 }
6313             }
6314
6315           constructor_fields = TREE_CHAIN (constructor_fields);
6316           /* Skip any nameless bit fields at the beginning.  */
6317           while (constructor_fields != 0
6318                  && DECL_C_BIT_FIELD (constructor_fields)
6319                  && DECL_NAME (constructor_fields) == 0)
6320             constructor_fields = TREE_CHAIN (constructor_fields);
6321         }
6322       else if (TREE_CODE (constructor_type) == UNION_TYPE)
6323         {
6324           tree fieldtype;
6325           enum tree_code fieldcode;
6326
6327           if (constructor_fields == 0)
6328             {
6329               pedwarn_init ("excess elements in union initializer");
6330               break;
6331             }
6332
6333           fieldtype = TREE_TYPE (constructor_fields);
6334           if (fieldtype != error_mark_node)
6335             fieldtype = TYPE_MAIN_VARIANT (fieldtype);
6336           fieldcode = TREE_CODE (fieldtype);
6337
6338           /* Warn that traditional C rejects initialization of unions.
6339              We skip the warning if the value is zero.  This is done
6340              under the assumption that the zero initializer in user
6341              code appears conditioned on e.g. __STDC__ to avoid
6342              "missing initializer" warnings and relies on default
6343              initialization to zero in the traditional C case.
6344              We also skip the warning if the initializer is designated,
6345              again on the assumption that this must be conditional on
6346              __STDC__ anyway (and we've already complained about the
6347              member-designator already).  */
6348           if (!in_system_header && !constructor_designated
6349               && !(value.value && (integer_zerop (value.value)
6350                                    || real_zerop (value.value))))
6351             warning (OPT_Wtraditional, "traditional C rejects initialization "
6352                      "of unions");
6353
6354           /* Accept a string constant to initialize a subarray.  */
6355           if (value.value != 0
6356               && fieldcode == ARRAY_TYPE
6357               && INTEGRAL_TYPE_P (TREE_TYPE (fieldtype))
6358               && string_flag)
6359             value.value = orig_value;
6360           /* Otherwise, if we have come to a subaggregate,
6361              and we don't have an element of its type, push into it.  */
6362           else if (value.value != 0
6363                    && value.value != error_mark_node
6364                    && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != fieldtype
6365                    && (fieldcode == RECORD_TYPE || fieldcode == ARRAY_TYPE
6366                        || fieldcode == UNION_TYPE))
6367             {
6368               push_init_level (1);
6369               continue;
6370             }
6371
6372           if (value.value)
6373             {
6374               push_member_name (constructor_fields);
6375               output_init_element (value.value, strict_string,
6376                                    fieldtype, constructor_fields, 1);
6377               RESTORE_SPELLING_DEPTH (constructor_depth);
6378             }
6379           else
6380             /* Do the bookkeeping for an element that was
6381                directly output as a constructor.  */
6382             {
6383               constructor_bit_index = DECL_SIZE (constructor_fields);
6384               constructor_unfilled_fields = TREE_CHAIN (constructor_fields);
6385             }
6386
6387           constructor_fields = 0;
6388         }
6389       else if (TREE_CODE (constructor_type) == ARRAY_TYPE)
6390         {
6391           tree elttype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
6392           enum tree_code eltcode = TREE_CODE (elttype);
6393
6394           /* Accept a string constant to initialize a subarray.  */
6395           if (value.value != 0
6396               && eltcode == ARRAY_TYPE
6397               && INTEGRAL_TYPE_P (TREE_TYPE (elttype))
6398               && string_flag)
6399             value.value = orig_value;
6400           /* Otherwise, if we have come to a subaggregate,
6401              and we don't have an element of its type, push into it.  */
6402           else if (value.value != 0
6403                    && value.value != error_mark_node
6404                    && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != elttype
6405                    && (eltcode == RECORD_TYPE || eltcode == ARRAY_TYPE
6406                        || eltcode == UNION_TYPE))
6407             {
6408               push_init_level (1);
6409               continue;
6410             }
6411
6412           if (constructor_max_index != 0
6413               && (tree_int_cst_lt (constructor_max_index, constructor_index)
6414                   || integer_all_onesp (constructor_max_index)))
6415             {
6416               pedwarn_init ("excess elements in array initializer");
6417               break;
6418             }
6419
6420           /* Now output the actual element.  */
6421           if (value.value)
6422             {
6423               push_array_bounds (tree_low_cst (constructor_index, 0));
6424               output_init_element (value.value, strict_string,
6425                                    elttype, constructor_index, 1);
6426               RESTORE_SPELLING_DEPTH (constructor_depth);
6427             }
6428
6429           constructor_index
6430             = size_binop (PLUS_EXPR, constructor_index, bitsize_one_node);
6431
6432           if (!value.value)
6433             /* If we are doing the bookkeeping for an element that was
6434                directly output as a constructor, we must update
6435                constructor_unfilled_index.  */
6436             constructor_unfilled_index = constructor_index;
6437         }
6438       else if (TREE_CODE (constructor_type) == VECTOR_TYPE)
6439         {
6440           tree elttype = TYPE_MAIN_VARIANT (TREE_TYPE (constructor_type));
6441
6442          /* Do a basic check of initializer size.  Note that vectors
6443             always have a fixed size derived from their type.  */
6444           if (tree_int_cst_lt (constructor_max_index, constructor_index))
6445             {
6446               pedwarn_init ("excess elements in vector initializer");
6447               break;
6448             }
6449
6450           /* Now output the actual element.  */
6451           if (value.value)
6452             output_init_element (value.value, strict_string,
6453                                  elttype, constructor_index, 1);
6454
6455           constructor_index
6456             = size_binop (PLUS_EXPR, constructor_index, bitsize_one_node);
6457
6458           if (!value.value)
6459             /* If we are doing the bookkeeping for an element that was
6460                directly output as a constructor, we must update
6461                constructor_unfilled_index.  */
6462             constructor_unfilled_index = constructor_index;
6463         }
6464
6465       /* Handle the sole element allowed in a braced initializer
6466          for a scalar variable.  */
6467       else if (constructor_type != error_mark_node
6468                && constructor_fields == 0)
6469         {
6470           pedwarn_init ("excess elements in scalar initializer");
6471           break;
6472         }
6473       else
6474         {
6475           if (value.value)
6476             output_init_element (value.value, strict_string,
6477                                  constructor_type, NULL_TREE, 1);
6478           constructor_fields = 0;
6479         }
6480
6481       /* Handle range initializers either at this level or anywhere higher
6482          in the designator stack.  */
6483       if (constructor_range_stack)
6484         {
6485           struct constructor_range_stack *p, *range_stack;
6486           int finish = 0;
6487
6488           range_stack = constructor_range_stack;
6489           constructor_range_stack = 0;
6490           while (constructor_stack != range_stack->stack)
6491             {
6492               gcc_assert (constructor_stack->implicit);
6493               process_init_element (pop_init_level (1));
6494             }
6495           for (p = range_stack;
6496                !p->range_end || tree_int_cst_equal (p->index, p->range_end);
6497                p = p->prev)
6498             {
6499               gcc_assert (constructor_stack->implicit);
6500               process_init_element (pop_init_level (1));
6501             }
6502
6503           p->index = size_binop (PLUS_EXPR, p->index, bitsize_one_node);
6504           if (tree_int_cst_equal (p->index, p->range_end) && !p->prev)
6505             finish = 1;
6506
6507           while (1)
6508             {
6509               constructor_index = p->index;
6510               constructor_fields = p->fields;
6511               if (finish && p->range_end && p->index == p->range_start)
6512                 {
6513                   finish = 0;
6514                   p->prev = 0;
6515                 }
6516               p = p->next;
6517               if (!p)
6518                 break;
6519               push_init_level (2);
6520               p->stack = constructor_stack;
6521               if (p->range_end && tree_int_cst_equal (p->index, p->range_end))
6522                 p->index = p->range_start;
6523             }
6524
6525           if (!finish)
6526             constructor_range_stack = range_stack;
6527           continue;
6528         }
6529
6530       break;
6531     }
6532
6533   constructor_range_stack = 0;
6534 }
6535 \f
6536 /* Build a complete asm-statement, whose components are a CV_QUALIFIER
6537    (guaranteed to be 'volatile' or null) and ARGS (represented using
6538    an ASM_EXPR node).  */
6539 tree
6540 build_asm_stmt (tree cv_qualifier, tree args)
6541 {
6542   if (!ASM_VOLATILE_P (args) && cv_qualifier)
6543     ASM_VOLATILE_P (args) = 1;
6544   return add_stmt (args);
6545 }
6546
6547 /* Build an asm-expr, whose components are a STRING, some OUTPUTS,
6548    some INPUTS, and some CLOBBERS.  The latter three may be NULL.
6549    SIMPLE indicates whether there was anything at all after the
6550    string in the asm expression -- asm("blah") and asm("blah" : )
6551    are subtly different.  We use a ASM_EXPR node to represent this.  */
6552 tree
6553 build_asm_expr (tree string, tree outputs, tree inputs, tree clobbers,
6554                 bool simple)
6555 {
6556   tree tail;
6557   tree args;
6558   int i;
6559   const char *constraint;
6560   const char **oconstraints;
6561   bool allows_mem, allows_reg, is_inout;
6562   int ninputs, noutputs;
6563
6564   ninputs = list_length (inputs);
6565   noutputs = list_length (outputs);
6566   oconstraints = (const char **) alloca (noutputs * sizeof (const char *));
6567
6568   string = resolve_asm_operand_names (string, outputs, inputs);
6569
6570   /* Remove output conversions that change the type but not the mode.  */
6571   for (i = 0, tail = outputs; tail; ++i, tail = TREE_CHAIN (tail))
6572     {
6573       tree output = TREE_VALUE (tail);
6574
6575       /* ??? Really, this should not be here.  Users should be using a
6576          proper lvalue, dammit.  But there's a long history of using casts
6577          in the output operands.  In cases like longlong.h, this becomes a
6578          primitive form of typechecking -- if the cast can be removed, then
6579          the output operand had a type of the proper width; otherwise we'll
6580          get an error.  Gross, but ...  */
6581       STRIP_NOPS (output);
6582
6583       if (!lvalue_or_else (output, lv_asm))
6584         output = error_mark_node;
6585
6586       constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tail)));
6587       oconstraints[i] = constraint;
6588
6589       if (parse_output_constraint (&constraint, i, ninputs, noutputs,
6590                                    &allows_mem, &allows_reg, &is_inout))
6591         {
6592           /* If the operand is going to end up in memory,
6593              mark it addressable.  */
6594           if (!allows_reg && !c_mark_addressable (output))
6595             output = error_mark_node;
6596         }
6597       else
6598         output = error_mark_node;
6599
6600       TREE_VALUE (tail) = output;
6601     }
6602
6603   for (i = 0, tail = inputs; tail; ++i, tail = TREE_CHAIN (tail))
6604     {
6605       tree input;
6606
6607       constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tail)));
6608       input = TREE_VALUE (tail);
6609
6610       if (parse_input_constraint (&constraint, i, ninputs, noutputs, 0,
6611                                   oconstraints, &allows_mem, &allows_reg))
6612         {
6613           /* If the operand is going to end up in memory,
6614              mark it addressable.  */
6615           if (!allows_reg && allows_mem)
6616             {
6617               /* Strip the nops as we allow this case.  FIXME, this really
6618                  should be rejected or made deprecated.  */
6619               STRIP_NOPS (input);
6620               if (!c_mark_addressable (input))
6621                 input = error_mark_node;
6622           }
6623         }
6624       else
6625         input = error_mark_node;
6626
6627       TREE_VALUE (tail) = input;
6628     }
6629
6630   args = build_stmt (ASM_EXPR, string, outputs, inputs, clobbers);
6631
6632   /* Simple asm statements are treated as volatile.  */
6633   if (simple)
6634     {
6635       ASM_VOLATILE_P (args) = 1;
6636       ASM_INPUT_P (args) = 1;
6637     }
6638
6639   return args;
6640 }
6641 \f
6642 /* Generate a goto statement to LABEL.  */
6643
6644 tree
6645 c_finish_goto_label (tree label)
6646 {
6647   tree decl = lookup_label (label);
6648   if (!decl)
6649     return NULL_TREE;
6650
6651   if (C_DECL_UNJUMPABLE_STMT_EXPR (decl))
6652     {
6653       error ("jump into statement expression");
6654       return NULL_TREE;
6655     }
6656
6657   if (C_DECL_UNJUMPABLE_VM (decl))
6658     {
6659       error ("jump into scope of identifier with variably modified type");
6660       return NULL_TREE;
6661     }
6662
6663   if (!C_DECL_UNDEFINABLE_STMT_EXPR (decl))
6664     {
6665       /* No jump from outside this statement expression context, so
6666          record that there is a jump from within this context.  */
6667       struct c_label_list *nlist;
6668       nlist = XOBNEW (&parser_obstack, struct c_label_list);
6669       nlist->next = label_context_stack_se->labels_used;
6670       nlist->label = decl;
6671       label_context_stack_se->labels_used = nlist;
6672     }
6673
6674   if (!C_DECL_UNDEFINABLE_VM (decl))
6675     {
6676       /* No jump from outside this context context of identifiers with
6677          variably modified type, so record that there is a jump from
6678          within this context.  */
6679       struct c_label_list *nlist;
6680       nlist = XOBNEW (&parser_obstack, struct c_label_list);
6681       nlist->next = label_context_stack_vm->labels_used;
6682       nlist->label = decl;
6683       label_context_stack_vm->labels_used = nlist;
6684     }
6685
6686   TREE_USED (decl) = 1;
6687   return add_stmt (build1 (GOTO_EXPR, void_type_node, decl));
6688 }
6689
6690 /* Generate a computed goto statement to EXPR.  */
6691
6692 tree
6693 c_finish_goto_ptr (tree expr)
6694 {
6695   if (pedantic)
6696     pedwarn ("ISO C forbids %<goto *expr;%>");
6697   expr = convert (ptr_type_node, expr);
6698   return add_stmt (build1 (GOTO_EXPR, void_type_node, expr));
6699 }
6700
6701 /* Generate a C `return' statement.  RETVAL is the expression for what
6702    to return, or a null pointer for `return;' with no value.  */
6703
6704 tree
6705 c_finish_return (tree retval)
6706 {
6707   tree valtype = TREE_TYPE (TREE_TYPE (current_function_decl));
6708
6709   if (TREE_THIS_VOLATILE (current_function_decl))
6710     warning (0, "function declared %<noreturn%> has a %<return%> statement");
6711
6712   if (!retval)
6713     {
6714       current_function_returns_null = 1;
6715       if ((warn_return_type || flag_isoc99)
6716           && valtype != 0 && TREE_CODE (valtype) != VOID_TYPE)
6717         pedwarn_c99 ("%<return%> with no value, in "
6718                      "function returning non-void");
6719     }
6720   else if (valtype == 0 || TREE_CODE (valtype) == VOID_TYPE)
6721     {
6722       current_function_returns_null = 1;
6723       if (pedantic || TREE_CODE (TREE_TYPE (retval)) != VOID_TYPE)
6724         pedwarn ("%<return%> with a value, in function returning void");
6725     }
6726   else
6727     {
6728       tree t = convert_for_assignment (valtype, retval, ic_return,
6729                                        NULL_TREE, NULL_TREE, 0);
6730       tree res = DECL_RESULT (current_function_decl);
6731       tree inner;
6732
6733       current_function_returns_value = 1;
6734       if (t == error_mark_node)
6735         return NULL_TREE;
6736
6737       inner = t = convert (TREE_TYPE (res), t);
6738
6739       /* Strip any conversions, additions, and subtractions, and see if
6740          we are returning the address of a local variable.  Warn if so.  */
6741       while (1)
6742         {
6743           switch (TREE_CODE (inner))
6744             {
6745             case NOP_EXPR:   case NON_LVALUE_EXPR:  case CONVERT_EXPR:
6746             case PLUS_EXPR:
6747               inner = TREE_OPERAND (inner, 0);
6748               continue;
6749
6750             case MINUS_EXPR:
6751               /* If the second operand of the MINUS_EXPR has a pointer
6752                  type (or is converted from it), this may be valid, so
6753                  don't give a warning.  */
6754               {
6755                 tree op1 = TREE_OPERAND (inner, 1);
6756
6757                 while (!POINTER_TYPE_P (TREE_TYPE (op1))
6758                        && (TREE_CODE (op1) == NOP_EXPR
6759                            || TREE_CODE (op1) == NON_LVALUE_EXPR
6760                            || TREE_CODE (op1) == CONVERT_EXPR))
6761                   op1 = TREE_OPERAND (op1, 0);
6762
6763                 if (POINTER_TYPE_P (TREE_TYPE (op1)))
6764                   break;
6765
6766                 inner = TREE_OPERAND (inner, 0);
6767                 continue;
6768               }
6769
6770             case ADDR_EXPR:
6771               inner = TREE_OPERAND (inner, 0);
6772
6773               while (REFERENCE_CLASS_P (inner)
6774                      && TREE_CODE (inner) != INDIRECT_REF)
6775                 inner = TREE_OPERAND (inner, 0);
6776
6777               if (DECL_P (inner)
6778                   && !DECL_EXTERNAL (inner)
6779                   && !TREE_STATIC (inner)
6780                   && DECL_CONTEXT (inner) == current_function_decl)
6781                 warning (0, "function returns address of local variable");
6782               break;
6783
6784             default:
6785               break;
6786             }
6787
6788           break;
6789         }
6790
6791       retval = build2 (MODIFY_EXPR, TREE_TYPE (res), res, t);
6792     }
6793
6794   return add_stmt (build_stmt (RETURN_EXPR, retval));
6795 }
6796 \f
6797 struct c_switch {
6798   /* The SWITCH_EXPR being built.  */
6799   tree switch_expr;
6800
6801   /* The original type of the testing expression, i.e. before the
6802      default conversion is applied.  */
6803   tree orig_type;
6804
6805   /* A splay-tree mapping the low element of a case range to the high
6806      element, or NULL_TREE if there is no high element.  Used to
6807      determine whether or not a new case label duplicates an old case
6808      label.  We need a tree, rather than simply a hash table, because
6809      of the GNU case range extension.  */
6810   splay_tree cases;
6811
6812   /* Number of nested statement expressions within this switch
6813      statement; if nonzero, case and default labels may not
6814      appear.  */
6815   unsigned int blocked_stmt_expr;
6816
6817   /* Scope of outermost declarations of identifiers with variably
6818      modified type within this switch statement; if nonzero, case and
6819      default labels may not appear.  */
6820   unsigned int blocked_vm;
6821
6822   /* The next node on the stack.  */
6823   struct c_switch *next;
6824 };
6825
6826 /* A stack of the currently active switch statements.  The innermost
6827    switch statement is on the top of the stack.  There is no need to
6828    mark the stack for garbage collection because it is only active
6829    during the processing of the body of a function, and we never
6830    collect at that point.  */
6831
6832 struct c_switch *c_switch_stack;
6833
6834 /* Start a C switch statement, testing expression EXP.  Return the new
6835    SWITCH_EXPR.  */
6836
6837 tree
6838 c_start_case (tree exp)
6839 {
6840   enum tree_code code;
6841   tree type, orig_type = error_mark_node;
6842   struct c_switch *cs;
6843
6844   if (exp != error_mark_node)
6845     {
6846       code = TREE_CODE (TREE_TYPE (exp));
6847       orig_type = TREE_TYPE (exp);
6848
6849       if (!INTEGRAL_TYPE_P (orig_type)
6850           && code != ERROR_MARK)
6851         {
6852           error ("switch quantity not an integer");
6853           exp = integer_zero_node;
6854           orig_type = error_mark_node;
6855         }
6856       else
6857         {
6858           type = TYPE_MAIN_VARIANT (TREE_TYPE (exp));
6859
6860           if (!in_system_header
6861               && (type == long_integer_type_node
6862                   || type == long_unsigned_type_node))
6863             warning (OPT_Wtraditional, "%<long%> switch expression not "
6864                      "converted to %<int%> in ISO C");
6865
6866           exp = default_conversion (exp);
6867           type = TREE_TYPE (exp);
6868         }
6869     }
6870
6871   /* Add this new SWITCH_EXPR to the stack.  */
6872   cs = XNEW (struct c_switch);
6873   cs->switch_expr = build3 (SWITCH_EXPR, orig_type, exp, NULL_TREE, NULL_TREE);
6874   cs->orig_type = orig_type;
6875   cs->cases = splay_tree_new (case_compare, NULL, NULL);
6876   cs->blocked_stmt_expr = 0;
6877   cs->blocked_vm = 0;
6878   cs->next = c_switch_stack;
6879   c_switch_stack = cs;
6880
6881   return add_stmt (cs->switch_expr);
6882 }
6883
6884 /* Process a case label.  */
6885
6886 tree
6887 do_case (tree low_value, tree high_value)
6888 {
6889   tree label = NULL_TREE;
6890
6891   if (c_switch_stack && !c_switch_stack->blocked_stmt_expr
6892       && !c_switch_stack->blocked_vm)
6893     {
6894       label = c_add_case_label (c_switch_stack->cases,
6895                                 SWITCH_COND (c_switch_stack->switch_expr),
6896                                 c_switch_stack->orig_type,
6897                                 low_value, high_value);
6898       if (label == error_mark_node)
6899         label = NULL_TREE;
6900     }
6901   else if (c_switch_stack && c_switch_stack->blocked_stmt_expr)
6902     {
6903       if (low_value)
6904         error ("case label in statement expression not containing "
6905                "enclosing switch statement");
6906       else
6907         error ("%<default%> label in statement expression not containing "
6908                "enclosing switch statement");
6909     }
6910   else if (c_switch_stack && c_switch_stack->blocked_vm)
6911     {
6912       if (low_value)
6913         error ("case label in scope of identifier with variably modified "
6914                "type not containing enclosing switch statement");
6915       else
6916         error ("%<default%> label in scope of identifier with variably "
6917                "modified type not containing enclosing switch statement");
6918     }
6919   else if (low_value)
6920     error ("case label not within a switch statement");
6921   else
6922     error ("%<default%> label not within a switch statement");
6923
6924   return label;
6925 }
6926
6927 /* Finish the switch statement.  */
6928
6929 void
6930 c_finish_case (tree body)
6931 {
6932   struct c_switch *cs = c_switch_stack;
6933   location_t switch_location;
6934
6935   SWITCH_BODY (cs->switch_expr) = body;
6936
6937   /* We must not be within a statement expression nested in the switch
6938      at this point; we might, however, be within the scope of an
6939      identifier with variably modified type nested in the switch.  */
6940   gcc_assert (!cs->blocked_stmt_expr);
6941
6942   /* Emit warnings as needed.  */
6943   if (EXPR_HAS_LOCATION (cs->switch_expr))
6944     switch_location = EXPR_LOCATION (cs->switch_expr);
6945   else
6946     switch_location = input_location;
6947   c_do_switch_warnings (cs->cases, switch_location,
6948                         TREE_TYPE (cs->switch_expr),
6949                         SWITCH_COND (cs->switch_expr));
6950
6951   /* Pop the stack.  */
6952   c_switch_stack = cs->next;
6953   splay_tree_delete (cs->cases);
6954   XDELETE (cs);
6955 }
6956 \f
6957 /* Emit an if statement.  IF_LOCUS is the location of the 'if'.  COND,
6958    THEN_BLOCK and ELSE_BLOCK are expressions to be used; ELSE_BLOCK
6959    may be null.  NESTED_IF is true if THEN_BLOCK contains another IF
6960    statement, and was not surrounded with parenthesis.  */
6961
6962 void
6963 c_finish_if_stmt (location_t if_locus, tree cond, tree then_block,
6964                   tree else_block, bool nested_if)
6965 {
6966   tree stmt;
6967
6968   /* Diagnose an ambiguous else if if-then-else is nested inside if-then.  */
6969   if (warn_parentheses && nested_if && else_block == NULL)
6970     {
6971       tree inner_if = then_block;
6972
6973       /* We know from the grammar productions that there is an IF nested
6974          within THEN_BLOCK.  Due to labels and c99 conditional declarations,
6975          it might not be exactly THEN_BLOCK, but should be the last
6976          non-container statement within.  */
6977       while (1)
6978         switch (TREE_CODE (inner_if))
6979           {
6980           case COND_EXPR:
6981             goto found;
6982           case BIND_EXPR:
6983             inner_if = BIND_EXPR_BODY (inner_if);
6984             break;
6985           case STATEMENT_LIST:
6986             inner_if = expr_last (then_block);
6987             break;
6988           case TRY_FINALLY_EXPR:
6989           case TRY_CATCH_EXPR:
6990             inner_if = TREE_OPERAND (inner_if, 0);
6991             break;
6992           default:
6993             gcc_unreachable ();
6994           }
6995     found:
6996
6997       if (COND_EXPR_ELSE (inner_if))
6998          warning (OPT_Wparentheses,
6999                   "%Hsuggest explicit braces to avoid ambiguous %<else%>",
7000                   &if_locus);
7001     }
7002
7003   /* Diagnose ";" via the special empty statement node that we create.  */
7004   if (extra_warnings)
7005     {
7006       if (TREE_CODE (then_block) == NOP_EXPR && !TREE_TYPE (then_block))
7007         {
7008           if (!else_block)
7009             warning (0, "%Hempty body in an if-statement",
7010                      EXPR_LOCUS (then_block));
7011           then_block = alloc_stmt_list ();
7012         }
7013       if (else_block
7014           && TREE_CODE (else_block) == NOP_EXPR
7015           && !TREE_TYPE (else_block))
7016         {
7017           warning (0, "%Hempty body in an else-statement",
7018                    EXPR_LOCUS (else_block));
7019           else_block = alloc_stmt_list ();
7020         }
7021     }
7022
7023   stmt = build3 (COND_EXPR, void_type_node, cond, then_block, else_block);
7024   SET_EXPR_LOCATION (stmt, if_locus);
7025   add_stmt (stmt);
7026 }
7027
7028 /* Emit a general-purpose loop construct.  START_LOCUS is the location of
7029    the beginning of the loop.  COND is the loop condition.  COND_IS_FIRST
7030    is false for DO loops.  INCR is the FOR increment expression.  BODY is
7031    the statement controlled by the loop.  BLAB is the break label.  CLAB is
7032    the continue label.  Everything is allowed to be NULL.  */
7033
7034 void
7035 c_finish_loop (location_t start_locus, tree cond, tree incr, tree body,
7036                tree blab, tree clab, bool cond_is_first)
7037 {
7038   tree entry = NULL, exit = NULL, t;
7039
7040   /* If the condition is zero don't generate a loop construct.  */
7041   if (cond && integer_zerop (cond))
7042     {
7043       if (cond_is_first)
7044         {
7045           t = build_and_jump (&blab);
7046           SET_EXPR_LOCATION (t, start_locus);
7047           add_stmt (t);
7048         }
7049     }
7050   else
7051     {
7052       tree top = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
7053
7054       /* If we have an exit condition, then we build an IF with gotos either
7055          out of the loop, or to the top of it.  If there's no exit condition,
7056          then we just build a jump back to the top.  */
7057       exit = build_and_jump (&LABEL_EXPR_LABEL (top));
7058
7059       if (cond && !integer_nonzerop (cond))
7060         {
7061           /* Canonicalize the loop condition to the end.  This means
7062              generating a branch to the loop condition.  Reuse the
7063              continue label, if possible.  */
7064           if (cond_is_first)
7065             {
7066               if (incr || !clab)
7067                 {
7068                   entry = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
7069                   t = build_and_jump (&LABEL_EXPR_LABEL (entry));
7070                 }
7071               else
7072                 t = build1 (GOTO_EXPR, void_type_node, clab);
7073               SET_EXPR_LOCATION (t, start_locus);
7074               add_stmt (t);
7075             }
7076
7077           t = build_and_jump (&blab);
7078           exit = build3 (COND_EXPR, void_type_node, cond, exit, t);
7079           exit = fold (exit);
7080           if (cond_is_first)
7081             SET_EXPR_LOCATION (exit, start_locus);
7082           else
7083             SET_EXPR_LOCATION (exit, input_location);
7084         }
7085
7086       add_stmt (top);
7087     }
7088
7089   if (body)
7090     add_stmt (body);
7091   if (clab)
7092     add_stmt (build1 (LABEL_EXPR, void_type_node, clab));
7093   if (incr)
7094     add_stmt (incr);
7095   if (entry)
7096     add_stmt (entry);
7097   if (exit)
7098     add_stmt (exit);
7099   if (blab)
7100     add_stmt (build1 (LABEL_EXPR, void_type_node, blab));
7101 }
7102
7103 tree
7104 c_finish_bc_stmt (tree *label_p, bool is_break)
7105 {
7106   bool skip;
7107   tree label = *label_p;
7108
7109   /* In switch statements break is sometimes stylistically used after
7110      a return statement.  This can lead to spurious warnings about
7111      control reaching the end of a non-void function when it is
7112      inlined.  Note that we are calling block_may_fallthru with
7113      language specific tree nodes; this works because
7114      block_may_fallthru returns true when given something it does not
7115      understand.  */
7116   skip = !block_may_fallthru (cur_stmt_list);
7117
7118   if (!label)
7119     {
7120       if (!skip)
7121         *label_p = label = create_artificial_label ();
7122     }
7123   else if (TREE_CODE (label) != LABEL_DECL)
7124     {
7125       if (is_break)
7126         error ("break statement not within loop or switch");
7127       else
7128         error ("continue statement not within a loop");
7129       return NULL_TREE;
7130     }
7131
7132   if (skip)
7133     return NULL_TREE;
7134
7135   return add_stmt (build1 (GOTO_EXPR, void_type_node, label));
7136 }
7137
7138 /* A helper routine for c_process_expr_stmt and c_finish_stmt_expr.  */
7139
7140 static void
7141 emit_side_effect_warnings (tree expr)
7142 {
7143   if (expr == error_mark_node)
7144     ;
7145   else if (!TREE_SIDE_EFFECTS (expr))
7146     {
7147       if (!VOID_TYPE_P (TREE_TYPE (expr)) && !TREE_NO_WARNING (expr))
7148         warning (0, "%Hstatement with no effect",
7149                  EXPR_HAS_LOCATION (expr) ? EXPR_LOCUS (expr) : &input_location);
7150     }
7151   else if (warn_unused_value)
7152     warn_if_unused_value (expr, input_location);
7153 }
7154
7155 /* Process an expression as if it were a complete statement.  Emit
7156    diagnostics, but do not call ADD_STMT.  */
7157
7158 tree
7159 c_process_expr_stmt (tree expr)
7160 {
7161   if (!expr)
7162     return NULL_TREE;
7163
7164   if (warn_sequence_point)
7165     verify_sequence_points (expr);
7166
7167   if (TREE_TYPE (expr) != error_mark_node
7168       && !COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (expr))
7169       && TREE_CODE (TREE_TYPE (expr)) != ARRAY_TYPE)
7170     error ("expression statement has incomplete type");
7171
7172   /* If we're not processing a statement expression, warn about unused values.
7173      Warnings for statement expressions will be emitted later, once we figure
7174      out which is the result.  */
7175   if (!STATEMENT_LIST_STMT_EXPR (cur_stmt_list)
7176       && (extra_warnings || warn_unused_value))
7177     emit_side_effect_warnings (expr);
7178
7179   /* If the expression is not of a type to which we cannot assign a line
7180      number, wrap the thing in a no-op NOP_EXPR.  */
7181   if (DECL_P (expr) || CONSTANT_CLASS_P (expr))
7182     expr = build1 (NOP_EXPR, TREE_TYPE (expr), expr);
7183
7184   if (EXPR_P (expr))
7185     SET_EXPR_LOCATION (expr, input_location);
7186
7187   return expr;
7188 }
7189
7190 /* Emit an expression as a statement.  */
7191
7192 tree
7193 c_finish_expr_stmt (tree expr)
7194 {
7195   if (expr)
7196     return add_stmt (c_process_expr_stmt (expr));
7197   else
7198     return NULL;
7199 }
7200
7201 /* Do the opposite and emit a statement as an expression.  To begin,
7202    create a new binding level and return it.  */
7203
7204 tree
7205 c_begin_stmt_expr (void)
7206 {
7207   tree ret;
7208   struct c_label_context_se *nstack;
7209   struct c_label_list *glist;
7210
7211   /* We must force a BLOCK for this level so that, if it is not expanded
7212      later, there is a way to turn off the entire subtree of blocks that
7213      are contained in it.  */
7214   keep_next_level ();
7215   ret = c_begin_compound_stmt (true);
7216   if (c_switch_stack)
7217     {
7218       c_switch_stack->blocked_stmt_expr++;
7219       gcc_assert (c_switch_stack->blocked_stmt_expr != 0);
7220     }
7221   for (glist = label_context_stack_se->labels_used;
7222        glist != NULL;
7223        glist = glist->next)
7224     {
7225       C_DECL_UNDEFINABLE_STMT_EXPR (glist->label) = 1;
7226     }
7227   nstack = XOBNEW (&parser_obstack, struct c_label_context_se);
7228   nstack->labels_def = NULL;
7229   nstack->labels_used = NULL;
7230   nstack->next = label_context_stack_se;
7231   label_context_stack_se = nstack;
7232
7233   /* Mark the current statement list as belonging to a statement list.  */
7234   STATEMENT_LIST_STMT_EXPR (ret) = 1;
7235
7236   return ret;
7237 }
7238
7239 tree
7240 c_finish_stmt_expr (tree body)
7241 {
7242   tree last, type, tmp, val;
7243   tree *last_p;
7244   struct c_label_list *dlist, *glist, *glist_prev = NULL;
7245
7246   body = c_end_compound_stmt (body, true);
7247   if (c_switch_stack)
7248     {
7249       gcc_assert (c_switch_stack->blocked_stmt_expr != 0);
7250       c_switch_stack->blocked_stmt_expr--;
7251     }
7252   /* It is no longer possible to jump to labels defined within this
7253      statement expression.  */
7254   for (dlist = label_context_stack_se->labels_def;
7255        dlist != NULL;
7256        dlist = dlist->next)
7257     {
7258       C_DECL_UNJUMPABLE_STMT_EXPR (dlist->label) = 1;
7259     }
7260   /* It is again possible to define labels with a goto just outside
7261      this statement expression.  */
7262   for (glist = label_context_stack_se->next->labels_used;
7263        glist != NULL;
7264        glist = glist->next)
7265     {
7266       C_DECL_UNDEFINABLE_STMT_EXPR (glist->label) = 0;
7267       glist_prev = glist;
7268     }
7269   if (glist_prev != NULL)
7270     glist_prev->next = label_context_stack_se->labels_used;
7271   else
7272     label_context_stack_se->next->labels_used
7273       = label_context_stack_se->labels_used;
7274   label_context_stack_se = label_context_stack_se->next;
7275
7276   /* Locate the last statement in BODY.  See c_end_compound_stmt
7277      about always returning a BIND_EXPR.  */
7278   last_p = &BIND_EXPR_BODY (body);
7279   last = BIND_EXPR_BODY (body);
7280
7281  continue_searching:
7282   if (TREE_CODE (last) == STATEMENT_LIST)
7283     {
7284       tree_stmt_iterator i;
7285
7286       /* This can happen with degenerate cases like ({ }).  No value.  */
7287       if (!TREE_SIDE_EFFECTS (last))
7288         return body;
7289
7290       /* If we're supposed to generate side effects warnings, process
7291          all of the statements except the last.  */
7292       if (extra_warnings || warn_unused_value)
7293         {
7294           for (i = tsi_start (last); !tsi_one_before_end_p (i); tsi_next (&i))
7295             emit_side_effect_warnings (tsi_stmt (i));
7296         }
7297       else
7298         i = tsi_last (last);
7299       last_p = tsi_stmt_ptr (i);
7300       last = *last_p;
7301     }
7302
7303   /* If the end of the list is exception related, then the list was split
7304      by a call to push_cleanup.  Continue searching.  */
7305   if (TREE_CODE (last) == TRY_FINALLY_EXPR
7306       || TREE_CODE (last) == TRY_CATCH_EXPR)
7307     {
7308       last_p = &TREE_OPERAND (last, 0);
7309       last = *last_p;
7310       goto continue_searching;
7311     }
7312
7313   /* In the case that the BIND_EXPR is not necessary, return the
7314      expression out from inside it.  */
7315   if (last == error_mark_node
7316       || (last == BIND_EXPR_BODY (body)
7317           && BIND_EXPR_VARS (body) == NULL))
7318     return last;
7319
7320   /* Extract the type of said expression.  */
7321   type = TREE_TYPE (last);
7322
7323   /* If we're not returning a value at all, then the BIND_EXPR that
7324      we already have is a fine expression to return.  */
7325   if (!type || VOID_TYPE_P (type))
7326     return body;
7327
7328   /* Now that we've located the expression containing the value, it seems
7329      silly to make voidify_wrapper_expr repeat the process.  Create a
7330      temporary of the appropriate type and stick it in a TARGET_EXPR.  */
7331   tmp = create_tmp_var_raw (type, NULL);
7332
7333   /* Unwrap a no-op NOP_EXPR as added by c_finish_expr_stmt.  This avoids
7334      tree_expr_nonnegative_p giving up immediately.  */
7335   val = last;
7336   if (TREE_CODE (val) == NOP_EXPR
7337       && TREE_TYPE (val) == TREE_TYPE (TREE_OPERAND (val, 0)))
7338     val = TREE_OPERAND (val, 0);
7339
7340   *last_p = build2 (MODIFY_EXPR, void_type_node, tmp, val);
7341   SET_EXPR_LOCUS (*last_p, EXPR_LOCUS (last));
7342
7343   return build4 (TARGET_EXPR, type, tmp, body, NULL_TREE, NULL_TREE);
7344 }
7345
7346 /* Begin the scope of an identifier of variably modified type, scope
7347    number SCOPE.  Jumping from outside this scope to inside it is not
7348    permitted.  */
7349
7350 void
7351 c_begin_vm_scope (unsigned int scope)
7352 {
7353   struct c_label_context_vm *nstack;
7354   struct c_label_list *glist;
7355
7356   gcc_assert (scope > 0);
7357   if (c_switch_stack && !c_switch_stack->blocked_vm)
7358     c_switch_stack->blocked_vm = scope;
7359   for (glist = label_context_stack_vm->labels_used;
7360        glist != NULL;
7361        glist = glist->next)
7362     {
7363       C_DECL_UNDEFINABLE_VM (glist->label) = 1;
7364     }
7365   nstack = XOBNEW (&parser_obstack, struct c_label_context_vm);
7366   nstack->labels_def = NULL;
7367   nstack->labels_used = NULL;
7368   nstack->scope = scope;
7369   nstack->next = label_context_stack_vm;
7370   label_context_stack_vm = nstack;
7371 }
7372
7373 /* End a scope which may contain identifiers of variably modified
7374    type, scope number SCOPE.  */
7375
7376 void
7377 c_end_vm_scope (unsigned int scope)
7378 {
7379   if (label_context_stack_vm == NULL)
7380     return;
7381   if (c_switch_stack && c_switch_stack->blocked_vm == scope)
7382     c_switch_stack->blocked_vm = 0;
7383   /* We may have a number of nested scopes of identifiers with
7384      variably modified type, all at this depth.  Pop each in turn.  */
7385   while (label_context_stack_vm->scope == scope)
7386     {
7387       struct c_label_list *dlist, *glist, *glist_prev = NULL;
7388
7389       /* It is no longer possible to jump to labels defined within this
7390          scope.  */
7391       for (dlist = label_context_stack_vm->labels_def;
7392            dlist != NULL;
7393            dlist = dlist->next)
7394         {
7395           C_DECL_UNJUMPABLE_VM (dlist->label) = 1;
7396         }
7397       /* It is again possible to define labels with a goto just outside
7398          this scope.  */
7399       for (glist = label_context_stack_vm->next->labels_used;
7400            glist != NULL;
7401            glist = glist->next)
7402         {
7403           C_DECL_UNDEFINABLE_VM (glist->label) = 0;
7404           glist_prev = glist;
7405         }
7406       if (glist_prev != NULL)
7407         glist_prev->next = label_context_stack_vm->labels_used;
7408       else
7409         label_context_stack_vm->next->labels_used
7410           = label_context_stack_vm->labels_used;
7411       label_context_stack_vm = label_context_stack_vm->next;
7412     }
7413 }
7414 \f
7415 /* Begin and end compound statements.  This is as simple as pushing
7416    and popping new statement lists from the tree.  */
7417
7418 tree
7419 c_begin_compound_stmt (bool do_scope)
7420 {
7421   tree stmt = push_stmt_list ();
7422   if (do_scope)
7423     push_scope ();
7424   return stmt;
7425 }
7426
7427 tree
7428 c_end_compound_stmt (tree stmt, bool do_scope)
7429 {
7430   tree block = NULL;
7431
7432   if (do_scope)
7433     {
7434       if (c_dialect_objc ())
7435         objc_clear_super_receiver ();
7436       block = pop_scope ();
7437     }
7438
7439   stmt = pop_stmt_list (stmt);
7440   stmt = c_build_bind_expr (block, stmt);
7441
7442   /* If this compound statement is nested immediately inside a statement
7443      expression, then force a BIND_EXPR to be created.  Otherwise we'll
7444      do the wrong thing for ({ { 1; } }) or ({ 1; { } }).  In particular,
7445      STATEMENT_LISTs merge, and thus we can lose track of what statement
7446      was really last.  */
7447   if (cur_stmt_list
7448       && STATEMENT_LIST_STMT_EXPR (cur_stmt_list)
7449       && TREE_CODE (stmt) != BIND_EXPR)
7450     {
7451       stmt = build3 (BIND_EXPR, void_type_node, NULL, stmt, NULL);
7452       TREE_SIDE_EFFECTS (stmt) = 1;
7453     }
7454
7455   return stmt;
7456 }
7457
7458 /* Queue a cleanup.  CLEANUP is an expression/statement to be executed
7459    when the current scope is exited.  EH_ONLY is true when this is not
7460    meant to apply to normal control flow transfer.  */
7461
7462 void
7463 push_cleanup (tree ARG_UNUSED (decl), tree cleanup, bool eh_only)
7464 {
7465   enum tree_code code;
7466   tree stmt, list;
7467   bool stmt_expr;
7468
7469   code = eh_only ? TRY_CATCH_EXPR : TRY_FINALLY_EXPR;
7470   stmt = build_stmt (code, NULL, cleanup);
7471   add_stmt (stmt);
7472   stmt_expr = STATEMENT_LIST_STMT_EXPR (cur_stmt_list);
7473   list = push_stmt_list ();
7474   TREE_OPERAND (stmt, 0) = list;
7475   STATEMENT_LIST_STMT_EXPR (list) = stmt_expr;
7476 }
7477 \f
7478 /* Build a binary-operation expression without default conversions.
7479    CODE is the kind of expression to build.
7480    This function differs from `build' in several ways:
7481    the data type of the result is computed and recorded in it,
7482    warnings are generated if arg data types are invalid,
7483    special handling for addition and subtraction of pointers is known,
7484    and some optimization is done (operations on narrow ints
7485    are done in the narrower type when that gives the same result).
7486    Constant folding is also done before the result is returned.
7487
7488    Note that the operands will never have enumeral types, or function
7489    or array types, because either they will have the default conversions
7490    performed or they have both just been converted to some other type in which
7491    the arithmetic is to be done.  */
7492
7493 tree
7494 build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
7495                  int convert_p)
7496 {
7497   tree type0, type1;
7498   enum tree_code code0, code1;
7499   tree op0, op1;
7500   const char *invalid_op_diag;
7501
7502   /* Expression code to give to the expression when it is built.
7503      Normally this is CODE, which is what the caller asked for,
7504      but in some special cases we change it.  */
7505   enum tree_code resultcode = code;
7506
7507   /* Data type in which the computation is to be performed.
7508      In the simplest cases this is the common type of the arguments.  */
7509   tree result_type = NULL;
7510
7511   /* Nonzero means operands have already been type-converted
7512      in whatever way is necessary.
7513      Zero means they need to be converted to RESULT_TYPE.  */
7514   int converted = 0;
7515
7516   /* Nonzero means create the expression with this type, rather than
7517      RESULT_TYPE.  */
7518   tree build_type = 0;
7519
7520   /* Nonzero means after finally constructing the expression
7521      convert it to this type.  */
7522   tree final_type = 0;
7523
7524   /* Nonzero if this is an operation like MIN or MAX which can
7525      safely be computed in short if both args are promoted shorts.
7526      Also implies COMMON.
7527      -1 indicates a bitwise operation; this makes a difference
7528      in the exact conditions for when it is safe to do the operation
7529      in a narrower mode.  */
7530   int shorten = 0;
7531
7532   /* Nonzero if this is a comparison operation;
7533      if both args are promoted shorts, compare the original shorts.
7534      Also implies COMMON.  */
7535   int short_compare = 0;
7536
7537   /* Nonzero if this is a right-shift operation, which can be computed on the
7538      original short and then promoted if the operand is a promoted short.  */
7539   int short_shift = 0;
7540
7541   /* Nonzero means set RESULT_TYPE to the common type of the args.  */
7542   int common = 0;
7543
7544   /* True means types are compatible as far as ObjC is concerned.  */
7545   bool objc_ok;
7546
7547   if (convert_p)
7548     {
7549       op0 = default_conversion (orig_op0);
7550       op1 = default_conversion (orig_op1);
7551     }
7552   else
7553     {
7554       op0 = orig_op0;
7555       op1 = orig_op1;
7556     }
7557
7558   type0 = TREE_TYPE (op0);
7559   type1 = TREE_TYPE (op1);
7560
7561   /* The expression codes of the data types of the arguments tell us
7562      whether the arguments are integers, floating, pointers, etc.  */
7563   code0 = TREE_CODE (type0);
7564   code1 = TREE_CODE (type1);
7565
7566   /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
7567   STRIP_TYPE_NOPS (op0);
7568   STRIP_TYPE_NOPS (op1);
7569
7570   /* If an error was already reported for one of the arguments,
7571      avoid reporting another error.  */
7572
7573   if (code0 == ERROR_MARK || code1 == ERROR_MARK)
7574     return error_mark_node;
7575
7576   if ((invalid_op_diag
7577        = targetm.invalid_binary_op (code, type0, type1)))
7578     {
7579       error (invalid_op_diag);
7580       return error_mark_node;
7581     }
7582
7583   objc_ok = objc_compare_types (type0, type1, -3, NULL_TREE);
7584
7585   switch (code)
7586     {
7587     case PLUS_EXPR:
7588       /* Handle the pointer + int case.  */
7589       if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7590         return pointer_int_sum (PLUS_EXPR, op0, op1);
7591       else if (code1 == POINTER_TYPE && code0 == INTEGER_TYPE)
7592         return pointer_int_sum (PLUS_EXPR, op1, op0);
7593       else
7594         common = 1;
7595       break;
7596
7597     case MINUS_EXPR:
7598       /* Subtraction of two similar pointers.
7599          We must subtract them as integers, then divide by object size.  */
7600       if (code0 == POINTER_TYPE && code1 == POINTER_TYPE
7601           && comp_target_types (type0, type1))
7602         return pointer_diff (op0, op1);
7603       /* Handle pointer minus int.  Just like pointer plus int.  */
7604       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7605         return pointer_int_sum (MINUS_EXPR, op0, op1);
7606       else
7607         common = 1;
7608       break;
7609
7610     case MULT_EXPR:
7611       common = 1;
7612       break;
7613
7614     case TRUNC_DIV_EXPR:
7615     case CEIL_DIV_EXPR:
7616     case FLOOR_DIV_EXPR:
7617     case ROUND_DIV_EXPR:
7618     case EXACT_DIV_EXPR:
7619       /* Floating point division by zero is a legitimate way to obtain
7620          infinities and NaNs.  */
7621       if (skip_evaluation == 0 && integer_zerop (op1))
7622         warning (OPT_Wdiv_by_zero, "division by zero");
7623
7624       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
7625            || code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
7626           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
7627               || code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE))
7628         {
7629           enum tree_code tcode0 = code0, tcode1 = code1;
7630
7631           if (code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
7632             tcode0 = TREE_CODE (TREE_TYPE (TREE_TYPE (op0)));
7633           if (code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE)
7634             tcode1 = TREE_CODE (TREE_TYPE (TREE_TYPE (op1)));
7635
7636           if (!(tcode0 == INTEGER_TYPE && tcode1 == INTEGER_TYPE))
7637             resultcode = RDIV_EXPR;
7638           else
7639             /* Although it would be tempting to shorten always here, that
7640                loses on some targets, since the modulo instruction is
7641                undefined if the quotient can't be represented in the
7642                computation mode.  We shorten only if unsigned or if
7643                dividing by something we know != -1.  */
7644             shorten = (TYPE_UNSIGNED (TREE_TYPE (orig_op0))
7645                        || (TREE_CODE (op1) == INTEGER_CST
7646                            && !integer_all_onesp (op1)));
7647           common = 1;
7648         }
7649       break;
7650
7651     case BIT_AND_EXPR:
7652     case BIT_IOR_EXPR:
7653     case BIT_XOR_EXPR:
7654       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7655         shorten = -1;
7656       else if (code0 == VECTOR_TYPE && code1 == VECTOR_TYPE)
7657         common = 1;
7658       break;
7659
7660     case TRUNC_MOD_EXPR:
7661     case FLOOR_MOD_EXPR:
7662       if (skip_evaluation == 0 && integer_zerop (op1))
7663         warning (OPT_Wdiv_by_zero, "division by zero");
7664
7665       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7666         {
7667           /* Although it would be tempting to shorten always here, that loses
7668              on some targets, since the modulo instruction is undefined if the
7669              quotient can't be represented in the computation mode.  We shorten
7670              only if unsigned or if dividing by something we know != -1.  */
7671           shorten = (TYPE_UNSIGNED (TREE_TYPE (orig_op0))
7672                      || (TREE_CODE (op1) == INTEGER_CST
7673                          && !integer_all_onesp (op1)));
7674           common = 1;
7675         }
7676       break;
7677
7678     case TRUTH_ANDIF_EXPR:
7679     case TRUTH_ORIF_EXPR:
7680     case TRUTH_AND_EXPR:
7681     case TRUTH_OR_EXPR:
7682     case TRUTH_XOR_EXPR:
7683       if ((code0 == INTEGER_TYPE || code0 == POINTER_TYPE
7684            || code0 == REAL_TYPE || code0 == COMPLEX_TYPE)
7685           && (code1 == INTEGER_TYPE || code1 == POINTER_TYPE
7686               || code1 == REAL_TYPE || code1 == COMPLEX_TYPE))
7687         {
7688           /* Result of these operations is always an int,
7689              but that does not mean the operands should be
7690              converted to ints!  */
7691           result_type = integer_type_node;
7692           op0 = c_common_truthvalue_conversion (op0);
7693           op1 = c_common_truthvalue_conversion (op1);
7694           converted = 1;
7695         }
7696       break;
7697
7698       /* Shift operations: result has same type as first operand;
7699          always convert second operand to int.
7700          Also set SHORT_SHIFT if shifting rightward.  */
7701
7702     case RSHIFT_EXPR:
7703       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7704         {
7705           if (TREE_CODE (op1) == INTEGER_CST && skip_evaluation == 0)
7706             {
7707               if (tree_int_cst_sgn (op1) < 0)
7708                 warning (0, "right shift count is negative");
7709               else
7710                 {
7711                   if (!integer_zerop (op1))
7712                     short_shift = 1;
7713
7714                   if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
7715                     warning (0, "right shift count >= width of type");
7716                 }
7717             }
7718
7719           /* Use the type of the value to be shifted.  */
7720           result_type = type0;
7721           /* Convert the shift-count to an integer, regardless of size
7722              of value being shifted.  */
7723           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
7724             op1 = convert (integer_type_node, op1);
7725           /* Avoid converting op1 to result_type later.  */
7726           converted = 1;
7727         }
7728       break;
7729
7730     case LSHIFT_EXPR:
7731       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
7732         {
7733           if (TREE_CODE (op1) == INTEGER_CST && skip_evaluation == 0)
7734             {
7735               if (tree_int_cst_sgn (op1) < 0)
7736                 warning (0, "left shift count is negative");
7737
7738               else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
7739                 warning (0, "left shift count >= width of type");
7740             }
7741
7742           /* Use the type of the value to be shifted.  */
7743           result_type = type0;
7744           /* Convert the shift-count to an integer, regardless of size
7745              of value being shifted.  */
7746           if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
7747             op1 = convert (integer_type_node, op1);
7748           /* Avoid converting op1 to result_type later.  */
7749           converted = 1;
7750         }
7751       break;
7752
7753     case EQ_EXPR:
7754     case NE_EXPR:
7755       if (code0 == REAL_TYPE || code1 == REAL_TYPE)
7756         warning (OPT_Wfloat_equal,
7757                  "comparing floating point with == or != is unsafe");
7758       /* Result of comparison is always int,
7759          but don't convert the args to int!  */
7760       build_type = integer_type_node;
7761       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
7762            || code0 == COMPLEX_TYPE)
7763           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
7764               || code1 == COMPLEX_TYPE))
7765         short_compare = 1;
7766       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
7767         {
7768           tree tt0 = TREE_TYPE (type0);
7769           tree tt1 = TREE_TYPE (type1);
7770           /* Anything compares with void *.  void * compares with anything.
7771              Otherwise, the targets must be compatible
7772              and both must be object or both incomplete.  */
7773           if (comp_target_types (type0, type1))
7774             result_type = common_pointer_type (type0, type1);
7775           else if (VOID_TYPE_P (tt0))
7776             {
7777               /* op0 != orig_op0 detects the case of something
7778                  whose value is 0 but which isn't a valid null ptr const.  */
7779               if (pedantic && (!integer_zerop (op0) || op0 != orig_op0)
7780                   && TREE_CODE (tt1) == FUNCTION_TYPE)
7781                 pedwarn ("ISO C forbids comparison of %<void *%>"
7782                          " with function pointer");
7783             }
7784           else if (VOID_TYPE_P (tt1))
7785             {
7786               if (pedantic && (!integer_zerop (op1) || op1 != orig_op1)
7787                   && TREE_CODE (tt0) == FUNCTION_TYPE)
7788                 pedwarn ("ISO C forbids comparison of %<void *%>"
7789                          " with function pointer");
7790             }
7791           else
7792             /* Avoid warning about the volatile ObjC EH puts on decls.  */
7793             if (!objc_ok)
7794               pedwarn ("comparison of distinct pointer types lacks a cast");
7795
7796           if (result_type == NULL_TREE)
7797             result_type = ptr_type_node;
7798         }
7799       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
7800                && integer_zerop (op1))
7801         result_type = type0;
7802       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
7803                && integer_zerop (op0))
7804         result_type = type1;
7805       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7806         {
7807           result_type = type0;
7808           pedwarn ("comparison between pointer and integer");
7809         }
7810       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
7811         {
7812           result_type = type1;
7813           pedwarn ("comparison between pointer and integer");
7814         }
7815       break;
7816
7817     case LE_EXPR:
7818     case GE_EXPR:
7819     case LT_EXPR:
7820     case GT_EXPR:
7821       build_type = integer_type_node;
7822       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
7823           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
7824         short_compare = 1;
7825       else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
7826         {
7827           if (comp_target_types (type0, type1))
7828             {
7829               result_type = common_pointer_type (type0, type1);
7830               if (!COMPLETE_TYPE_P (TREE_TYPE (type0))
7831                   != !COMPLETE_TYPE_P (TREE_TYPE (type1)))
7832                 pedwarn ("comparison of complete and incomplete pointers");
7833               else if (pedantic
7834                        && TREE_CODE (TREE_TYPE (type0)) == FUNCTION_TYPE)
7835                 pedwarn ("ISO C forbids ordered comparisons of pointers to functions");
7836             }
7837           else
7838             {
7839               result_type = ptr_type_node;
7840               pedwarn ("comparison of distinct pointer types lacks a cast");
7841             }
7842         }
7843       else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
7844                && integer_zerop (op1))
7845         {
7846           result_type = type0;
7847           if (pedantic || extra_warnings)
7848             pedwarn ("ordered comparison of pointer with integer zero");
7849         }
7850       else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
7851                && integer_zerop (op0))
7852         {
7853           result_type = type1;
7854           if (pedantic)
7855             pedwarn ("ordered comparison of pointer with integer zero");
7856         }
7857       else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
7858         {
7859           result_type = type0;
7860           pedwarn ("comparison between pointer and integer");
7861         }
7862       else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
7863         {
7864           result_type = type1;
7865           pedwarn ("comparison between pointer and integer");
7866         }
7867       break;
7868
7869     default:
7870       gcc_unreachable ();
7871     }
7872
7873   if (code0 == ERROR_MARK || code1 == ERROR_MARK)
7874     return error_mark_node;
7875
7876   if (code0 == VECTOR_TYPE && code1 == VECTOR_TYPE
7877       && (!tree_int_cst_equal (TYPE_SIZE (type0), TYPE_SIZE (type1))
7878           || !same_scalar_type_ignoring_signedness (TREE_TYPE (type0),
7879                                                     TREE_TYPE (type1))))
7880     {
7881       binary_op_error (code);
7882       return error_mark_node;
7883     }
7884
7885   if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE || code0 == COMPLEX_TYPE
7886        || code0 == VECTOR_TYPE)
7887       &&
7888       (code1 == INTEGER_TYPE || code1 == REAL_TYPE || code1 == COMPLEX_TYPE
7889        || code1 == VECTOR_TYPE))
7890     {
7891       int none_complex = (code0 != COMPLEX_TYPE && code1 != COMPLEX_TYPE);
7892
7893       if (shorten || common || short_compare)
7894         result_type = c_common_type (type0, type1);
7895
7896       /* For certain operations (which identify themselves by shorten != 0)
7897          if both args were extended from the same smaller type,
7898          do the arithmetic in that type and then extend.
7899
7900          shorten !=0 and !=1 indicates a bitwise operation.
7901          For them, this optimization is safe only if
7902          both args are zero-extended or both are sign-extended.
7903          Otherwise, we might change the result.
7904          Eg, (short)-1 | (unsigned short)-1 is (int)-1
7905          but calculated in (unsigned short) it would be (unsigned short)-1.  */
7906
7907       if (shorten && none_complex)
7908         {
7909           int unsigned0, unsigned1;
7910           tree arg0 = get_narrower (op0, &unsigned0);
7911           tree arg1 = get_narrower (op1, &unsigned1);
7912           /* UNS is 1 if the operation to be done is an unsigned one.  */
7913           int uns = TYPE_UNSIGNED (result_type);
7914           tree type;
7915
7916           final_type = result_type;
7917
7918           /* Handle the case that OP0 (or OP1) does not *contain* a conversion
7919              but it *requires* conversion to FINAL_TYPE.  */
7920
7921           if ((TYPE_PRECISION (TREE_TYPE (op0))
7922                == TYPE_PRECISION (TREE_TYPE (arg0)))
7923               && TREE_TYPE (op0) != final_type)
7924             unsigned0 = TYPE_UNSIGNED (TREE_TYPE (op0));
7925           if ((TYPE_PRECISION (TREE_TYPE (op1))
7926                == TYPE_PRECISION (TREE_TYPE (arg1)))
7927               && TREE_TYPE (op1) != final_type)
7928             unsigned1 = TYPE_UNSIGNED (TREE_TYPE (op1));
7929
7930           /* Now UNSIGNED0 is 1 if ARG0 zero-extends to FINAL_TYPE.  */
7931
7932           /* For bitwise operations, signedness of nominal type
7933              does not matter.  Consider only how operands were extended.  */
7934           if (shorten == -1)
7935             uns = unsigned0;
7936
7937           /* Note that in all three cases below we refrain from optimizing
7938              an unsigned operation on sign-extended args.
7939              That would not be valid.  */
7940
7941           /* Both args variable: if both extended in same way
7942              from same width, do it in that width.
7943              Do it unsigned if args were zero-extended.  */
7944           if ((TYPE_PRECISION (TREE_TYPE (arg0))
7945                < TYPE_PRECISION (result_type))
7946               && (TYPE_PRECISION (TREE_TYPE (arg1))
7947                   == TYPE_PRECISION (TREE_TYPE (arg0)))
7948               && unsigned0 == unsigned1
7949               && (unsigned0 || !uns))
7950             result_type
7951               = c_common_signed_or_unsigned_type
7952               (unsigned0, common_type (TREE_TYPE (arg0), TREE_TYPE (arg1)));
7953           else if (TREE_CODE (arg0) == INTEGER_CST
7954                    && (unsigned1 || !uns)
7955                    && (TYPE_PRECISION (TREE_TYPE (arg1))
7956                        < TYPE_PRECISION (result_type))
7957                    && (type
7958                        = c_common_signed_or_unsigned_type (unsigned1,
7959                                                            TREE_TYPE (arg1)),
7960                        int_fits_type_p (arg0, type)))
7961             result_type = type;
7962           else if (TREE_CODE (arg1) == INTEGER_CST
7963                    && (unsigned0 || !uns)
7964                    && (TYPE_PRECISION (TREE_TYPE (arg0))
7965                        < TYPE_PRECISION (result_type))
7966                    && (type
7967                        = c_common_signed_or_unsigned_type (unsigned0,
7968                                                            TREE_TYPE (arg0)),
7969                        int_fits_type_p (arg1, type)))
7970             result_type = type;
7971         }
7972
7973       /* Shifts can be shortened if shifting right.  */
7974
7975       if (short_shift)
7976         {
7977           int unsigned_arg;
7978           tree arg0 = get_narrower (op0, &unsigned_arg);
7979
7980           final_type = result_type;
7981
7982           if (arg0 == op0 && final_type == TREE_TYPE (op0))
7983             unsigned_arg = TYPE_UNSIGNED (TREE_TYPE (op0));
7984
7985           if (TYPE_PRECISION (TREE_TYPE (arg0)) < TYPE_PRECISION (result_type)
7986               /* We can shorten only if the shift count is less than the
7987                  number of bits in the smaller type size.  */
7988               && compare_tree_int (op1, TYPE_PRECISION (TREE_TYPE (arg0))) < 0
7989               /* We cannot drop an unsigned shift after sign-extension.  */
7990               && (!TYPE_UNSIGNED (final_type) || unsigned_arg))
7991             {
7992               /* Do an unsigned shift if the operand was zero-extended.  */
7993               result_type
7994                 = c_common_signed_or_unsigned_type (unsigned_arg,
7995                                                     TREE_TYPE (arg0));
7996               /* Convert value-to-be-shifted to that type.  */
7997               if (TREE_TYPE (op0) != result_type)
7998                 op0 = convert (result_type, op0);
7999               converted = 1;
8000             }
8001         }
8002
8003       /* Comparison operations are shortened too but differently.
8004          They identify themselves by setting short_compare = 1.  */
8005
8006       if (short_compare)
8007         {
8008           /* Don't write &op0, etc., because that would prevent op0
8009              from being kept in a register.
8010              Instead, make copies of the our local variables and
8011              pass the copies by reference, then copy them back afterward.  */
8012           tree xop0 = op0, xop1 = op1, xresult_type = result_type;
8013           enum tree_code xresultcode = resultcode;
8014           tree val
8015             = shorten_compare (&xop0, &xop1, &xresult_type, &xresultcode);
8016
8017           if (val != 0)
8018             return val;
8019
8020           op0 = xop0, op1 = xop1;
8021           converted = 1;
8022           resultcode = xresultcode;
8023
8024           if (warn_sign_compare && skip_evaluation == 0)
8025             {
8026               int op0_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op0));
8027               int op1_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op1));
8028               int unsignedp0, unsignedp1;
8029               tree primop0 = get_narrower (op0, &unsignedp0);
8030               tree primop1 = get_narrower (op1, &unsignedp1);
8031
8032               xop0 = orig_op0;
8033               xop1 = orig_op1;
8034               STRIP_TYPE_NOPS (xop0);
8035               STRIP_TYPE_NOPS (xop1);
8036
8037               /* Give warnings for comparisons between signed and unsigned
8038                  quantities that may fail.
8039
8040                  Do the checking based on the original operand trees, so that
8041                  casts will be considered, but default promotions won't be.
8042
8043                  Do not warn if the comparison is being done in a signed type,
8044                  since the signed type will only be chosen if it can represent
8045                  all the values of the unsigned type.  */
8046               if (!TYPE_UNSIGNED (result_type))
8047                 /* OK */;
8048               /* Do not warn if both operands are the same signedness.  */
8049               else if (op0_signed == op1_signed)
8050                 /* OK */;
8051               else
8052                 {
8053                   tree sop, uop;
8054
8055                   if (op0_signed)
8056                     sop = xop0, uop = xop1;
8057                   else
8058                     sop = xop1, uop = xop0;
8059
8060                   /* Do not warn if the signed quantity is an
8061                      unsuffixed integer literal (or some static
8062                      constant expression involving such literals or a
8063                      conditional expression involving such literals)
8064                      and it is non-negative.  */
8065                   if (tree_expr_nonnegative_p (sop))
8066                     /* OK */;
8067                   /* Do not warn if the comparison is an equality operation,
8068                      the unsigned quantity is an integral constant, and it
8069                      would fit in the result if the result were signed.  */
8070                   else if (TREE_CODE (uop) == INTEGER_CST
8071                            && (resultcode == EQ_EXPR || resultcode == NE_EXPR)
8072                            && int_fits_type_p
8073                            (uop, c_common_signed_type (result_type)))
8074                     /* OK */;
8075                   /* Do not warn if the unsigned quantity is an enumeration
8076                      constant and its maximum value would fit in the result
8077                      if the result were signed.  */
8078                   else if (TREE_CODE (uop) == INTEGER_CST
8079                            && TREE_CODE (TREE_TYPE (uop)) == ENUMERAL_TYPE
8080                            && int_fits_type_p
8081                            (TYPE_MAX_VALUE (TREE_TYPE (uop)),
8082                             c_common_signed_type (result_type)))
8083                     /* OK */;
8084                   else
8085                     warning (0, "comparison between signed and unsigned");
8086                 }
8087
8088               /* Warn if two unsigned values are being compared in a size
8089                  larger than their original size, and one (and only one) is the
8090                  result of a `~' operator.  This comparison will always fail.
8091
8092                  Also warn if one operand is a constant, and the constant
8093                  does not have all bits set that are set in the ~ operand
8094                  when it is extended.  */
8095
8096               if ((TREE_CODE (primop0) == BIT_NOT_EXPR)
8097                   != (TREE_CODE (primop1) == BIT_NOT_EXPR))
8098                 {
8099                   if (TREE_CODE (primop0) == BIT_NOT_EXPR)
8100                     primop0 = get_narrower (TREE_OPERAND (primop0, 0),
8101                                             &unsignedp0);
8102                   else
8103                     primop1 = get_narrower (TREE_OPERAND (primop1, 0),
8104                                             &unsignedp1);
8105
8106                   if (host_integerp (primop0, 0) || host_integerp (primop1, 0))
8107                     {
8108                       tree primop;
8109                       HOST_WIDE_INT constant, mask;
8110                       int unsignedp, bits;
8111
8112                       if (host_integerp (primop0, 0))
8113                         {
8114                           primop = primop1;
8115                           unsignedp = unsignedp1;
8116                           constant = tree_low_cst (primop0, 0);
8117                         }
8118                       else
8119                         {
8120                           primop = primop0;
8121                           unsignedp = unsignedp0;
8122                           constant = tree_low_cst (primop1, 0);
8123                         }
8124
8125                       bits = TYPE_PRECISION (TREE_TYPE (primop));
8126                       if (bits < TYPE_PRECISION (result_type)
8127                           && bits < HOST_BITS_PER_WIDE_INT && unsignedp)
8128                         {
8129                           mask = (~(HOST_WIDE_INT) 0) << bits;
8130                           if ((mask & constant) != mask)
8131                             warning (0, "comparison of promoted ~unsigned with constant");
8132                         }
8133                     }
8134                   else if (unsignedp0 && unsignedp1
8135                            && (TYPE_PRECISION (TREE_TYPE (primop0))
8136                                < TYPE_PRECISION (result_type))
8137                            && (TYPE_PRECISION (TREE_TYPE (primop1))
8138                                < TYPE_PRECISION (result_type)))
8139                     warning (0, "comparison of promoted ~unsigned with unsigned");
8140                 }
8141             }
8142         }
8143     }
8144
8145   /* At this point, RESULT_TYPE must be nonzero to avoid an error message.
8146      If CONVERTED is zero, both args will be converted to type RESULT_TYPE.
8147      Then the expression will be built.
8148      It will be given type FINAL_TYPE if that is nonzero;
8149      otherwise, it will be given type RESULT_TYPE.  */
8150
8151   if (!result_type)
8152     {
8153       binary_op_error (code);
8154       return error_mark_node;
8155     }
8156
8157   if (!converted)
8158     {
8159       if (TREE_TYPE (op0) != result_type)
8160         op0 = convert (result_type, op0);
8161       if (TREE_TYPE (op1) != result_type)
8162         op1 = convert (result_type, op1);
8163
8164       /* This can happen if one operand has a vector type, and the other
8165          has a different type.  */
8166       if (TREE_CODE (op0) == ERROR_MARK || TREE_CODE (op1) == ERROR_MARK)
8167         return error_mark_node;
8168     }
8169
8170   if (build_type == NULL_TREE)
8171     build_type = result_type;
8172
8173   {
8174     tree result = build2 (resultcode, build_type, op0, op1);
8175
8176     /* Treat expressions in initializers specially as they can't trap.  */
8177     result = require_constant_value ? fold_initializer (result)
8178                                     : fold (result);
8179
8180     if (final_type != 0)
8181       result = convert (final_type, result);
8182     return result;
8183   }
8184 }
8185
8186
8187 /* Convert EXPR to be a truth-value, validating its type for this
8188    purpose.  */
8189
8190 tree
8191 c_objc_common_truthvalue_conversion (tree expr)
8192 {
8193   switch (TREE_CODE (TREE_TYPE (expr)))
8194     {
8195     case ARRAY_TYPE:
8196       error ("used array that cannot be converted to pointer where scalar is required");
8197       return error_mark_node;
8198
8199     case RECORD_TYPE:
8200       error ("used struct type value where scalar is required");
8201       return error_mark_node;
8202
8203     case UNION_TYPE:
8204       error ("used union type value where scalar is required");
8205       return error_mark_node;
8206
8207     case FUNCTION_TYPE:
8208       gcc_unreachable ();
8209
8210     default:
8211       break;
8212     }
8213
8214   /* ??? Should we also give an error for void and vectors rather than
8215      leaving those to give errors later?  */
8216   return c_common_truthvalue_conversion (expr);
8217 }
8218 \f
8219
8220 /* Convert EXPR to a contained DECL, updating *TC, *TI and *SE as
8221    required.  */
8222
8223 tree
8224 c_expr_to_decl (tree expr, bool *tc ATTRIBUTE_UNUSED,
8225                 bool *ti ATTRIBUTE_UNUSED, bool *se)
8226 {
8227   if (TREE_CODE (expr) == COMPOUND_LITERAL_EXPR)
8228     {
8229       tree decl = COMPOUND_LITERAL_EXPR_DECL (expr);
8230       /* Executing a compound literal inside a function reinitializes
8231          it.  */
8232       if (!TREE_STATIC (decl))
8233         *se = true;
8234       return decl;
8235     }
8236   else
8237     return expr;
8238 }