Home | History | Annotate | Line # | Download | only in lint1
tree.c revision 1.342
      1 /*	$NetBSD: tree.c,v 1.342 2021/08/21 08:29:59 rillig Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1994, 1995 Jochen Pohl
      5  * All Rights Reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *      This product includes software developed by Jochen Pohl for
     18  *	The NetBSD Project.
     19  * 4. The name of the author may not be used to endorse or promote products
     20  *    derived from this software without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     25  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     27  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     31  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     32  */
     33 
     34 #if HAVE_NBTOOL_CONFIG_H
     35 #include "nbtool_config.h"
     36 #endif
     37 
     38 #include <sys/cdefs.h>
     39 #if defined(__RCSID) && !defined(lint)
     40 __RCSID("$NetBSD: tree.c,v 1.342 2021/08/21 08:29:59 rillig Exp $");
     41 #endif
     42 
     43 #include <float.h>
     44 #include <limits.h>
     45 #include <math.h>
     46 #include <signal.h>
     47 #include <stdlib.h>
     48 #include <string.h>
     49 
     50 #include "lint1.h"
     51 #include "cgram.h"
     52 
     53 static	tnode_t	*build_integer_constant(tspec_t, int64_t);
     54 static	void	check_pointer_comparison(op_t,
     55 					 const tnode_t *, const tnode_t *);
     56 static	bool	check_assign_types_compatible(op_t, int,
     57 					      const tnode_t *, const tnode_t *);
     58 static	void	check_bad_enum_operation(op_t,
     59 					 const tnode_t *, const tnode_t *);
     60 static	void	check_enum_type_mismatch(op_t, int,
     61 				         const tnode_t *, const tnode_t *);
     62 static	void	check_enum_int_mismatch(op_t, int,
     63 					const tnode_t *, const tnode_t *);
     64 static	tnode_t	*new_tnode(op_t, type_t *, tnode_t *, tnode_t *);
     65 static	void	balance(op_t, tnode_t **, tnode_t **);
     66 static	void	warn_incompatible_types(op_t, const type_t *, tspec_t,
     67 					const type_t *, tspec_t);
     68 static	void	warn_incompatible_pointers(const mod_t *,
     69 					   const type_t *, const type_t *);
     70 static	bool	has_constant_member(const type_t *);
     71 static	void	check_prototype_conversion(int, tspec_t, tspec_t, type_t *,
     72 					   tnode_t *);
     73 static	void	check_integer_conversion(op_t, int, tspec_t, tspec_t, type_t *,
     74 					 tnode_t *);
     75 static	void	check_pointer_integer_conversion(op_t, tspec_t, type_t *,
     76 						 tnode_t *);
     77 static	void	check_pointer_conversion(tnode_t *, type_t *);
     78 static	tnode_t	*build_struct_access(op_t, tnode_t *, tnode_t *);
     79 static	tnode_t	*build_prepost_incdec(op_t, tnode_t *);
     80 static	tnode_t	*build_real_imag(op_t, tnode_t *);
     81 static	tnode_t	*build_address(tnode_t *, bool);
     82 static	tnode_t	*build_plus_minus(op_t, tnode_t *, tnode_t *);
     83 static	tnode_t	*build_bit_shift(op_t, tnode_t *, tnode_t *);
     84 static	tnode_t	*build_colon(tnode_t *, tnode_t *);
     85 static	tnode_t	*build_assignment(op_t, tnode_t *, tnode_t *);
     86 static	tnode_t	*plength(type_t *);
     87 static	tnode_t	*fold(tnode_t *);
     88 static	tnode_t	*fold_test(tnode_t *);
     89 static	tnode_t	*fold_float(tnode_t *);
     90 static	tnode_t	*check_function_arguments(type_t *, tnode_t *);
     91 static	tnode_t	*check_prototype_argument(int, type_t *, tnode_t *);
     92 static	void	check_null_effect(const tnode_t *);
     93 static	void	check_array_index(tnode_t *, bool);
     94 static	void	check_integer_comparison(op_t, tnode_t *, tnode_t *);
     95 static	void	check_precedence_confusion(tnode_t *);
     96 
     97 extern sig_atomic_t fpe;
     98 
     99 static const char *
    100 op_name(op_t op)
    101 {
    102 	return modtab[op].m_name;
    103 }
    104 
    105 /* Build 'pointer to tp', 'array of tp' or 'function returning tp'. */
    106 type_t *
    107 derive_type(type_t *tp, tspec_t t)
    108 {
    109 	type_t	*tp2;
    110 
    111 	tp2 = getblk(sizeof(*tp2));
    112 	tp2->t_tspec = t;
    113 	tp2->t_subt = tp;
    114 	return tp2;
    115 }
    116 
    117 /*
    118  * Build 'pointer to tp', 'array of tp' or 'function returning tp'.  The
    119  * memory is freed at the end of the current expression.
    120  */
    121 type_t *
    122 expr_derive_type(type_t *tp, tspec_t t)
    123 {
    124 	type_t	*tp2;
    125 
    126 	tp2 = expr_zalloc(sizeof(*tp2));
    127 	tp2->t_tspec = t;
    128 	tp2->t_subt = tp;
    129 	return tp2;
    130 }
    131 
    132 /*
    133  * Create a node for a constant.
    134  */
    135 tnode_t *
    136 build_constant(type_t *tp, val_t *v)
    137 {
    138 	tnode_t	*n;
    139 
    140 	n = expr_zalloc_tnode();
    141 	n->tn_op = CON;
    142 	n->tn_type = tp;
    143 	n->tn_val = expr_zalloc(sizeof(*n->tn_val));
    144 	n->tn_val->v_tspec = tp->t_tspec;
    145 	n->tn_val->v_unsigned_since_c90 = v->v_unsigned_since_c90;
    146 	n->tn_val->v_u = v->v_u;
    147 	free(v);
    148 	return n;
    149 }
    150 
    151 static tnode_t *
    152 build_integer_constant(tspec_t t, int64_t q)
    153 {
    154 	tnode_t	*n;
    155 
    156 	n = expr_zalloc_tnode();
    157 	n->tn_op = CON;
    158 	n->tn_type = gettyp(t);
    159 	n->tn_val = expr_zalloc(sizeof(*n->tn_val));
    160 	n->tn_val->v_tspec = t;
    161 	n->tn_val->v_quad = q;
    162 	return n;
    163 }
    164 
    165 static void
    166 fallback_symbol(sym_t *sym)
    167 {
    168 
    169 	if (fallback_symbol_strict_bool(sym))
    170 		return;
    171 
    172 	if (block_level > 0 && (strcmp(sym->s_name, "__FUNCTION__") == 0 ||
    173 			   strcmp(sym->s_name, "__PRETTY_FUNCTION__") == 0)) {
    174 		/* __FUNCTION__/__PRETTY_FUNCTION__ is a GCC extension */
    175 		gnuism(316);
    176 		sym->s_type = derive_type(gettyp(CHAR), PTR);
    177 		sym->s_type->t_const = true;
    178 		return;
    179 	}
    180 
    181 	if (block_level > 0 && strcmp(sym->s_name, "__func__") == 0) {
    182 		if (!Sflag)
    183 			/* __func__ is a C9X feature */
    184 			warning(317);
    185 		sym->s_type = derive_type(gettyp(CHAR), PTR);
    186 		sym->s_type->t_const = true;
    187 		return;
    188 	}
    189 
    190 	/* '%s' undefined */
    191 	error(99, sym->s_name);
    192 }
    193 
    194 /* https://gcc.gnu.org/onlinedocs/gcc/C-Extensions.html */
    195 static bool
    196 is_gcc_builtin(const char *name)
    197 {
    198 	return strncmp(name, "__atomic_", 9) == 0 ||
    199 	       strncmp(name, "__builtin_", 10) == 0;
    200 }
    201 
    202 /*
    203  * Create a node for a name (symbol table entry).
    204  * follow_token is the token which follows the name.
    205  */
    206 tnode_t *
    207 build_name(sym_t *sym, int follow_token)
    208 {
    209 	tnode_t	*n;
    210 
    211 	if (sym->s_scl == NOSCL) {
    212 		sym->s_scl = EXTERN;
    213 		sym->s_def = DECL;
    214 		if (follow_token == T_LPAREN) {
    215 			if (gflag && is_gcc_builtin(sym->s_name)) {
    216 				/*
    217 				 * Do not warn about these, just assume that
    218 				 * they are regular functions compatible with
    219 				 * non-prototype calling conventions.
    220 				 */
    221 			} else if (Sflag) {
    222 				/* function '%s' implicitly declared to ... */
    223 				warning(215, sym->s_name);
    224 			} else if (sflag) {
    225 				/* function '%s' implicitly declared to ... */
    226 				warning(215, sym->s_name);
    227 			}
    228 			/*
    229 			 * XXX if tflag is set the symbol should be
    230 			 * exported to level 0
    231 			 */
    232 			sym->s_type = derive_type(sym->s_type, FUNC);
    233 		} else {
    234 			fallback_symbol(sym);
    235 		}
    236 	}
    237 
    238 	lint_assert(sym->s_kind == FVFT || sym->s_kind == FMEMBER);
    239 
    240 	n = expr_zalloc_tnode();
    241 	n->tn_type = sym->s_type;
    242 	if (sym->s_scl != CTCONST) {
    243 		n->tn_op = NAME;
    244 		n->tn_sym = sym;
    245 		if (sym->s_kind == FVFT && sym->s_type->t_tspec != FUNC)
    246 			n->tn_lvalue = true;
    247 	} else {
    248 		n->tn_op = CON;
    249 		n->tn_val = expr_zalloc(sizeof(*n->tn_val));
    250 		*n->tn_val = sym->s_value;
    251 	}
    252 
    253 	return n;
    254 }
    255 
    256 tnode_t *
    257 build_string(strg_t *strg)
    258 {
    259 	size_t	len;
    260 	tnode_t	*n;
    261 
    262 	len = strg->st_len;
    263 
    264 	n = expr_zalloc_tnode();
    265 
    266 	n->tn_op = STRING;
    267 	n->tn_type = expr_derive_type(gettyp(strg->st_tspec), ARRAY);
    268 	n->tn_type->t_dim = len + 1;
    269 	n->tn_lvalue = true;
    270 
    271 	n->tn_string = expr_zalloc(sizeof(*n->tn_string));
    272 	n->tn_string->st_tspec = strg->st_tspec;
    273 	n->tn_string->st_len = len;
    274 
    275 	if (strg->st_tspec == CHAR) {
    276 		n->tn_string->st_cp = expr_zalloc(len + 1);
    277 		(void)memcpy(n->tn_string->st_cp, strg->st_cp, len + 1);
    278 		free(strg->st_cp);
    279 	} else {
    280 		size_t size = (len + 1) * sizeof(*n->tn_string->st_wcp);
    281 		n->tn_string->st_wcp = expr_zalloc(size);
    282 		(void)memcpy(n->tn_string->st_wcp, strg->st_wcp, size);
    283 		free(strg->st_wcp);
    284 	}
    285 	free(strg);
    286 
    287 	return n;
    288 }
    289 
    290 /*
    291  * Returns a symbol which has the same name as the msym argument and is a
    292  * member of the struct or union specified by the tn argument.
    293  */
    294 sym_t *
    295 struct_or_union_member(tnode_t *tn, op_t op, sym_t *msym)
    296 {
    297 	struct_or_union	*str;
    298 	type_t	*tp;
    299 	sym_t	*sym, *csym;
    300 	bool	eq;
    301 	tspec_t	t;
    302 
    303 	/*
    304 	 * Remove the member if it was unknown until now, which means
    305 	 * that no defined struct or union has a member with the same name.
    306 	 */
    307 	if (msym->s_scl == NOSCL) {
    308 		/* type '%s' does not have member '%s' */
    309 		error(101, type_name(tn->tn_type), msym->s_name);
    310 		rmsym(msym);
    311 		msym->s_kind = FMEMBER;
    312 		msym->s_scl = MOS;
    313 		msym->s_styp = expr_zalloc(sizeof(*msym->s_styp));
    314 		msym->s_styp->sou_tag = expr_zalloc(
    315 		    sizeof(*msym->s_styp->sou_tag));
    316 		msym->s_styp->sou_tag->s_name = unnamed;
    317 		msym->s_value.v_tspec = INT;
    318 		return msym;
    319 	}
    320 
    321 	/* Set str to the tag of which msym is expected to be a member. */
    322 	str = NULL;
    323 	t = (tp = tn->tn_type)->t_tspec;
    324 	if (op == POINT) {
    325 		if (t == STRUCT || t == UNION)
    326 			str = tp->t_str;
    327 	} else if (op == ARROW && t == PTR) {
    328 		t = (tp = tp->t_subt)->t_tspec;
    329 		if (t == STRUCT || t == UNION)
    330 			str = tp->t_str;
    331 	}
    332 
    333 	/*
    334 	 * If this struct/union has a member with the name of msym, return it.
    335 	 */
    336 	if (str != NULL) {
    337 		for (sym = msym; sym != NULL; sym = sym->s_link) {
    338 			if (sym->s_scl != MOS && sym->s_scl != MOU)
    339 				continue;
    340 			if (sym->s_styp != str)
    341 				continue;
    342 			if (strcmp(sym->s_name, msym->s_name) != 0)
    343 				continue;
    344 			return sym;
    345 		}
    346 	}
    347 
    348 	/*
    349 	 * Set eq to false if there are struct/union members with the same
    350 	 * name and different types and/or offsets.
    351 	 */
    352 	eq = true;
    353 	for (csym = msym; csym != NULL; csym = csym->s_link) {
    354 		if (csym->s_scl != MOS && csym->s_scl != MOU)
    355 			continue;
    356 		if (strcmp(msym->s_name, csym->s_name) != 0)
    357 			continue;
    358 		for (sym = csym->s_link; sym != NULL; sym = sym->s_link) {
    359 			bool w;
    360 
    361 			if (sym->s_scl != MOS && sym->s_scl != MOU)
    362 				continue;
    363 			if (strcmp(csym->s_name, sym->s_name) != 0)
    364 				continue;
    365 			if (csym->s_value.v_quad != sym->s_value.v_quad) {
    366 				eq = false;
    367 				break;
    368 			}
    369 			w = false;
    370 			eq = eqtype(csym->s_type, sym->s_type,
    371 			    false, false, &w) && !w;
    372 			if (!eq)
    373 				break;
    374 			if (csym->s_bitfield != sym->s_bitfield) {
    375 				eq = false;
    376 				break;
    377 			}
    378 			if (csym->s_bitfield) {
    379 				type_t	*tp1, *tp2;
    380 
    381 				tp1 = csym->s_type;
    382 				tp2 = sym->s_type;
    383 				if (tp1->t_flen != tp2->t_flen) {
    384 					eq = false;
    385 					break;
    386 				}
    387 				if (tp1->t_foffs != tp2->t_foffs) {
    388 					eq = false;
    389 					break;
    390 				}
    391 			}
    392 		}
    393 		if (!eq)
    394 			break;
    395 	}
    396 
    397 	/*
    398 	 * Now handle the case in which the left operand refers really
    399 	 * to a struct/union, but the right operand is not member of it.
    400 	 */
    401 	if (str != NULL) {
    402 		if (eq && tflag) {
    403 			/* illegal member use: %s */
    404 			warning(102, msym->s_name);
    405 		} else {
    406 			/* illegal member use: %s */
    407 			error(102, msym->s_name);
    408 		}
    409 		return msym;
    410 	}
    411 
    412 	/*
    413 	 * Now the left operand of ARROW does not point to a struct/union
    414 	 * or the left operand of POINT is no struct/union.
    415 	 */
    416 	if (eq) {
    417 		if (op == POINT) {
    418 			if (tflag) {
    419 				/* left operand of '.' must be struct ... */
    420 				warning(103, type_name(tn->tn_type));
    421 			} else {
    422 				/* left operand of '.' must be struct ... */
    423 				error(103, type_name(tn->tn_type));
    424 			}
    425 		} else {
    426 			if (tflag && tn->tn_type->t_tspec == PTR) {
    427 				/* left operand of '->' must be pointer ... */
    428 				warning(104, type_name(tn->tn_type));
    429 			} else {
    430 				/* left operand of '->' must be pointer ... */
    431 				error(104, type_name(tn->tn_type));
    432 			}
    433 		}
    434 	} else {
    435 		if (tflag) {
    436 			/* non-unique member requires struct/union %s */
    437 			error(105, op == POINT ? "object" : "pointer");
    438 		} else {
    439 			/* unacceptable operand of '%s' */
    440 			error(111, op_name(op));
    441 		}
    442 	}
    443 
    444 	return msym;
    445 }
    446 
    447 tnode_t *
    448 build_generic_selection(const tnode_t *expr,
    449 			struct generic_association *sel)
    450 {
    451 	tnode_t *default_result = NULL;
    452 
    453 	for (; sel != NULL; sel = sel->ga_prev)
    454 		if (expr != NULL &&
    455 		    eqtype(sel->ga_arg, expr->tn_type, false, false, NULL))
    456 			return sel->ga_result;
    457 		else if (sel->ga_arg == NULL)
    458 			default_result = sel->ga_result;
    459 	return default_result;
    460 }
    461 
    462 /*
    463  * Create a tree node. Called for most operands except function calls,
    464  * sizeof and casts.
    465  *
    466  * op	operator
    467  * ln	left operand
    468  * rn	if not NULL, right operand
    469  */
    470 tnode_t *
    471 build_binary(tnode_t *ln, op_t op, tnode_t *rn)
    472 {
    473 	const mod_t *mp;
    474 	tnode_t	*ntn;
    475 	type_t	*rettp;
    476 
    477 	mp = &modtab[op];
    478 
    479 	/* If there was an error in one of the operands, return. */
    480 	if (ln == NULL || (mp->m_binary && rn == NULL))
    481 		return NULL;
    482 
    483 	/*
    484 	 * Apply class conversions to the left operand, but only if its
    485 	 * value is needed or it is compared with null.
    486 	 */
    487 	if (mp->m_left_value_context || mp->m_left_test_context)
    488 		ln = cconv(ln);
    489 	/*
    490 	 * The right operand is almost always in a test or value context,
    491 	 * except if it is a struct or union member.
    492 	 */
    493 	if (mp->m_binary && op != ARROW && op != POINT)
    494 		rn = cconv(rn);
    495 
    496 	/*
    497 	 * Print some warnings for comparisons of unsigned values with
    498 	 * constants lower than or equal to null. This must be done
    499 	 * before promote() because otherwise unsigned char and unsigned
    500 	 * short would be promoted to int. Also types are tested to be
    501 	 * CHAR, which would also become int.
    502 	 */
    503 	if (mp->m_comparison)
    504 		check_integer_comparison(op, ln, rn);
    505 
    506 	/*
    507 	 * Promote the left operand if it is in a test or value context
    508 	 */
    509 	if (mp->m_left_value_context || mp->m_left_test_context)
    510 		ln = promote(op, false, ln);
    511 	/*
    512 	 * Promote the right operand, but only if it is no struct or
    513 	 * union member, or if it is not to be assigned to the left operand
    514 	 */
    515 	if (mp->m_binary && op != ARROW && op != POINT &&
    516 	    op != ASSIGN && op != RETURN && op != INIT) {
    517 		rn = promote(op, false, rn);
    518 	}
    519 
    520 	/*
    521 	 * If the result of the operation is different for signed or
    522 	 * unsigned operands and one of the operands is signed only in
    523 	 * ANSI C, print a warning.
    524 	 */
    525 	if (mp->m_warn_if_left_unsigned_in_c90 &&
    526 	    ln->tn_op == CON && ln->tn_val->v_unsigned_since_c90) {
    527 		/* ANSI C treats constant as unsigned, op %s */
    528 		warning(218, mp->m_name);
    529 		ln->tn_val->v_unsigned_since_c90 = false;
    530 	}
    531 	if (mp->m_warn_if_right_unsigned_in_c90 &&
    532 	    rn->tn_op == CON && rn->tn_val->v_unsigned_since_c90) {
    533 		/* ANSI C treats constant as unsigned, op %s */
    534 		warning(218, mp->m_name);
    535 		rn->tn_val->v_unsigned_since_c90 = false;
    536 	}
    537 
    538 	/* Make sure both operands are of the same type */
    539 	if (mp->m_balance_operands || (tflag && (op == SHL || op == SHR)))
    540 		balance(op, &ln, &rn);
    541 
    542 	/*
    543 	 * Check types for compatibility with the operation and mutual
    544 	 * compatibility. Return if there are serious problems.
    545 	 */
    546 	if (!typeok(op, 0, ln, rn))
    547 		return NULL;
    548 
    549 	/* And now create the node. */
    550 	switch (op) {
    551 	case POINT:
    552 	case ARROW:
    553 		ntn = build_struct_access(op, ln, rn);
    554 		break;
    555 	case INCAFT:
    556 	case DECAFT:
    557 	case INCBEF:
    558 	case DECBEF:
    559 		ntn = build_prepost_incdec(op, ln);
    560 		break;
    561 	case ADDR:
    562 		ntn = build_address(ln, false);
    563 		break;
    564 	case INDIR:
    565 		ntn = new_tnode(INDIR, ln->tn_type->t_subt, ln, NULL);
    566 		break;
    567 	case PLUS:
    568 	case MINUS:
    569 		ntn = build_plus_minus(op, ln, rn);
    570 		break;
    571 	case SHL:
    572 	case SHR:
    573 		ntn = build_bit_shift(op, ln, rn);
    574 		break;
    575 	case COLON:
    576 		ntn = build_colon(ln, rn);
    577 		break;
    578 	case ASSIGN:
    579 	case MULASS:
    580 	case DIVASS:
    581 	case MODASS:
    582 	case ADDASS:
    583 	case SUBASS:
    584 	case SHLASS:
    585 	case SHRASS:
    586 	case ANDASS:
    587 	case XORASS:
    588 	case ORASS:
    589 	case RETURN:
    590 	case INIT:
    591 		ntn = build_assignment(op, ln, rn);
    592 		break;
    593 	case COMMA:
    594 	case QUEST:
    595 		ntn = new_tnode(op, rn->tn_type, ln, rn);
    596 		break;
    597 	case REAL:
    598 	case IMAG:
    599 		ntn = build_real_imag(op, ln);
    600 		break;
    601 	default:
    602 		rettp = mp->m_returns_bool
    603 		    ? gettyp(Tflag ? BOOL : INT) : ln->tn_type;
    604 		lint_assert(mp->m_binary || rn == NULL);
    605 		ntn = new_tnode(op, rettp, ln, rn);
    606 		break;
    607 	}
    608 
    609 	/* Return if an error occurred. */
    610 	if (ntn == NULL)
    611 		return NULL;
    612 
    613 	/* Print a warning if precedence confusion is possible */
    614 	if (mp->m_possible_precedence_confusion)
    615 		check_precedence_confusion(ntn);
    616 
    617 	/*
    618 	 * Print a warning if one of the operands is in a context where
    619 	 * it is compared with null and if this operand is a constant.
    620 	 */
    621 	if (mp->m_left_test_context) {
    622 		if (ln->tn_op == CON ||
    623 		    ((mp->m_binary && op != QUEST) && rn->tn_op == CON)) {
    624 			if (hflag && !constcond_flag &&
    625 			    !ln->tn_system_dependent)
    626 				/* constant in conditional context */
    627 				warning(161);
    628 		}
    629 	}
    630 
    631 	/* Fold if the operator requires it */
    632 	if (mp->m_fold_constant_operands) {
    633 		if (ln->tn_op == CON && (!mp->m_binary || rn->tn_op == CON)) {
    634 			if (mp->m_left_test_context) {
    635 				ntn = fold_test(ntn);
    636 			} else if (is_floating(ntn->tn_type->t_tspec)) {
    637 				ntn = fold_float(ntn);
    638 			} else {
    639 				ntn = fold(ntn);
    640 			}
    641 		} else if (op == QUEST && ln->tn_op == CON) {
    642 			ntn = ln->tn_val->v_quad != 0
    643 			    ? rn->tn_left : rn->tn_right;
    644 		}
    645 	}
    646 
    647 	return ntn;
    648 }
    649 
    650 tnode_t *
    651 build_unary(op_t op, tnode_t *tn)
    652 {
    653 	return build_binary(tn, op, NULL);
    654 }
    655 
    656 tnode_t *
    657 build_member_access(tnode_t *ln, op_t op, sbuf_t *member)
    658 {
    659 	sym_t	*msym;
    660 
    661 	if (ln == NULL)
    662 		return NULL;
    663 
    664 	if (op == ARROW) {
    665 		/* must do this before struct_or_union_member is called */
    666 		ln = cconv(ln);
    667 	}
    668 	msym = struct_or_union_member(ln, op, getsym(member));
    669 	return build_binary(ln, op, build_name(msym, 0));
    670 }
    671 
    672 /*
    673  * Perform class conversions.
    674  *
    675  * Arrays of type T are converted into pointers to type T.
    676  * Functions are converted to pointers to functions.
    677  * Lvalues are converted to rvalues.
    678  *
    679  * C99 6.3 "Conversions"
    680  * C99 6.3.2 "Other operands"
    681  * C99 6.3.2.1 "Lvalues, arrays, and function designators"
    682  */
    683 tnode_t *
    684 cconv(tnode_t *tn)
    685 {
    686 	type_t	*tp;
    687 
    688 	/*
    689 	 * Array-lvalue (array of type T) is converted into rvalue
    690 	 * (pointer to type T)
    691 	 */
    692 	if (tn->tn_type->t_tspec == ARRAY) {
    693 		if (!tn->tn_lvalue) {
    694 			/* XXX print correct operator */
    695 			/* %soperand of '%s' must be lvalue */
    696 			gnuism(114, "", op_name(ADDR));
    697 		}
    698 		tn = new_tnode(ADDR,
    699 		    expr_derive_type(tn->tn_type->t_subt, PTR), tn, NULL);
    700 	}
    701 
    702 	/*
    703 	 * Expression of type function (function with return value of type T)
    704 	 * in rvalue-expression (pointer to function with return value
    705 	 * of type T)
    706 	 */
    707 	if (tn->tn_type->t_tspec == FUNC)
    708 		tn = build_address(tn, true);
    709 
    710 	/* lvalue to rvalue */
    711 	if (tn->tn_lvalue) {
    712 		tp = expr_dup_type(tn->tn_type);
    713 		/* C99 6.3.2.1p2 sentence 2 says to remove the qualifiers. */
    714 		tp->t_const = tp->t_volatile = false;
    715 		tn = new_tnode(LOAD, tp, tn, NULL);
    716 	}
    717 
    718 	return tn;
    719 }
    720 
    721 const tnode_t *
    722 before_conversion(const tnode_t *tn)
    723 {
    724 	while (tn->tn_op == CVT && !tn->tn_cast)
    725 		tn = tn->tn_left;
    726 	return tn;
    727 }
    728 
    729 static bool
    730 is_null_pointer(const tnode_t *tn)
    731 {
    732 	tspec_t t = tn->tn_type->t_tspec;
    733 
    734 	return ((t == PTR && tn->tn_type->t_subt->t_tspec == VOID) ||
    735 		is_integer(t))
    736 	       && (tn->tn_op == CON && tn->tn_val->v_quad == 0);
    737 }
    738 
    739 static bool
    740 typeok_incdec(op_t op, const tnode_t *tn, const type_t *tp)
    741 {
    742 	/* operand has scalar type (checked in typeok) */
    743 	if (!tn->tn_lvalue) {
    744 		if (tn->tn_op == CVT && tn->tn_cast &&
    745 		    tn->tn_left->tn_op == LOAD) {
    746 			/* a cast does not yield an lvalue */
    747 			error(163);
    748 		}
    749 		/* %soperand of '%s' must be lvalue */
    750 		error(114, "", op_name(op));
    751 		return false;
    752 	} else if (tp->t_const) {
    753 		if (!tflag)
    754 			/* %soperand of '%s' must be modifiable lvalue */
    755 			warning(115, "", op_name(op));
    756 	}
    757 	return true;
    758 }
    759 
    760 static bool
    761 typeok_address(const mod_t *mp,
    762 	       const tnode_t *tn, const type_t *tp, tspec_t t)
    763 {
    764 	if (t == ARRAY || t == FUNC) {
    765 		/* ok, a warning comes later (in build_address()) */
    766 	} else if (!tn->tn_lvalue) {
    767 		if (tn->tn_op == CVT && tn->tn_cast &&
    768 		    tn->tn_left->tn_op == LOAD) {
    769 			/* a cast does not yield an lvalue */
    770 			error(163);
    771 		}
    772 		/* %soperand of '%s' must be lvalue */
    773 		error(114, "", mp->m_name);
    774 		return false;
    775 	} else if (is_scalar(t)) {
    776 		if (tp->t_bitfield) {
    777 			/* cannot take address of bit-field */
    778 			error(112);
    779 			return false;
    780 		}
    781 	} else if (t != STRUCT && t != UNION) {
    782 		/* unacceptable operand of '%s' */
    783 		error(111, mp->m_name);
    784 		return false;
    785 	}
    786 	if (tn->tn_op == NAME && tn->tn_sym->s_reg) {
    787 		/* cannot take address of register %s */
    788 		error(113, tn->tn_sym->s_name);
    789 		return false;
    790 	}
    791 	return true;
    792 }
    793 
    794 static bool
    795 typeok_star(tspec_t t)
    796 {
    797 	/* until now there were no type checks for this operator */
    798 	if (t != PTR) {
    799 		/* cannot dereference non-pointer type */
    800 		error(96);
    801 		return false;
    802 	}
    803 	return true;
    804 }
    805 
    806 static bool
    807 typeok_plus(op_t op,
    808 	    const type_t *ltp, tspec_t lt,
    809 	    const type_t *rtp, tspec_t rt)
    810 {
    811 	/* operands have scalar types (checked above) */
    812 	if ((lt == PTR && !is_integer(rt)) || (rt == PTR && !is_integer(lt))) {
    813 		warn_incompatible_types(op, ltp, lt, rtp, rt);
    814 		return false;
    815 	}
    816 	return true;
    817 }
    818 
    819 static bool
    820 typeok_minus(op_t op,
    821 	     const type_t *ltp, tspec_t lt,
    822 	     const type_t *rtp, tspec_t rt)
    823 {
    824 	/* operands have scalar types (checked above) */
    825 	if (lt == PTR && (!is_integer(rt) && rt != PTR)) {
    826 		warn_incompatible_types(op, ltp, lt, rtp, rt);
    827 		return false;
    828 	} else if (rt == PTR && lt != PTR) {
    829 		warn_incompatible_types(op, ltp, lt, rtp, rt);
    830 		return false;
    831 	}
    832 	if (lt == PTR && rt == PTR) {
    833 		if (!eqtype(ltp->t_subt, rtp->t_subt, true, false, NULL)) {
    834 			/* illegal pointer subtraction */
    835 			error(116);
    836 		}
    837 	}
    838 	return true;
    839 }
    840 
    841 static void
    842 typeok_shr(const mod_t *mp,
    843 	   const tnode_t *ln, tspec_t lt,
    844 	   const tnode_t *rn, tspec_t rt)
    845 {
    846 	tspec_t olt, ort;
    847 
    848 	olt = before_conversion(ln)->tn_type->t_tspec;
    849 	ort = before_conversion(rn)->tn_type->t_tspec;
    850 
    851 	/* operands have integer types (checked above) */
    852 	if (pflag && !is_uinteger(olt)) {
    853 		/*
    854 		 * The left operand is signed. This means that
    855 		 * the operation is (possibly) nonportable.
    856 		 */
    857 		if (ln->tn_op != CON) {
    858 			/* bitwise '%s' on signed value possibly nonportable */
    859 			warning(117, mp->m_name);
    860 		} else if (ln->tn_val->v_quad < 0) {
    861 			/* bitwise '%s' on signed value nonportable */
    862 			warning(120, mp->m_name);
    863 		}
    864 	} else if (!tflag && !sflag && !is_uinteger(olt) && is_uinteger(ort)) {
    865 		/*
    866 		 * The left operand would become unsigned in
    867 		 * traditional C.
    868 		 */
    869 		if (hflag && !Sflag &&
    870 		    (ln->tn_op != CON || ln->tn_val->v_quad < 0)) {
    871 			/* semantics of '%s' change in ANSI C; use ... */
    872 			warning(118, mp->m_name);
    873 		}
    874 	} else if (!tflag && !sflag && !is_uinteger(olt) && !is_uinteger(ort) &&
    875 		   portable_size_in_bits(lt) < portable_size_in_bits(rt)) {
    876 		/*
    877 		 * In traditional C the left operand would be extended,
    878 		 * possibly with 1, and then shifted.
    879 		 */
    880 		if (hflag && !Sflag &&
    881 		    (ln->tn_op != CON || ln->tn_val->v_quad < 0)) {
    882 			/* semantics of '%s' change in ANSI C; use ... */
    883 			warning(118, mp->m_name);
    884 		}
    885 	}
    886 }
    887 
    888 static void
    889 typeok_shl(const mod_t *mp, tspec_t lt, tspec_t rt)
    890 {
    891 	/*
    892 	 * C90 does not perform balancing for shift operations,
    893 	 * but traditional C does. If the width of the right operand
    894 	 * is greater than the width of the left operand, then in
    895 	 * traditional C the left operand would be extended to the
    896 	 * width of the right operand. For SHL this may result in
    897 	 * different results.
    898 	 */
    899 	if (portable_size_in_bits(lt) < portable_size_in_bits(rt)) {
    900 		/*
    901 		 * XXX If both operands are constant, make sure
    902 		 * that there is really a difference between
    903 		 * ANSI C and traditional C.
    904 		 */
    905 		if (hflag && !Sflag)
    906 			/* semantics of '%s' change in ANSI C; use ... */
    907 			warning(118, mp->m_name);
    908 	}
    909 }
    910 
    911 static void
    912 typeok_shift(tspec_t lt, const tnode_t *rn, tspec_t rt)
    913 {
    914 	if (rn->tn_op != CON)
    915 		return;
    916 
    917 	if (!is_uinteger(rt) && rn->tn_val->v_quad < 0) {
    918 		/* negative shift */
    919 		warning(121);
    920 	} else if ((uint64_t)rn->tn_val->v_quad ==
    921 		   (uint64_t)size_in_bits(lt)) {
    922 		/* shift equal to size of object */
    923 		warning(267);
    924 	} else if ((uint64_t)rn->tn_val->v_quad > (uint64_t)size_in_bits(lt)) {
    925 		/* shift amount %llu is greater than bit-size %llu of '%s' */
    926 		warning(122, (unsigned long long)rn->tn_val->v_quad,
    927 		    (unsigned long long)size_in_bits(lt),
    928 		    tspec_name(lt));
    929 	}
    930 }
    931 
    932 static bool
    933 is_typeok_eq(const tnode_t *ln, tspec_t lt, const tnode_t *rn, tspec_t rt)
    934 {
    935 	if (lt == PTR && is_null_pointer(rn))
    936 		return true;
    937 	if (rt == PTR && is_null_pointer(ln))
    938 		return true;
    939 	return false;
    940 }
    941 
    942 static bool
    943 typeok_ordered_comparison(op_t op,
    944 			  const tnode_t *ln, const type_t *ltp, tspec_t lt,
    945 			  const tnode_t *rn, const type_t *rtp, tspec_t rt)
    946 {
    947 	if (lt == PTR && rt == PTR) {
    948 		check_pointer_comparison(op, ln, rn);
    949 		return true;
    950 	}
    951 
    952 	if (lt != PTR && rt != PTR)
    953 		return true;
    954 
    955 	if (!is_integer(lt) && !is_integer(rt)) {
    956 		warn_incompatible_types(op, ltp, lt, rtp, rt);
    957 		return false;
    958 	}
    959 
    960 	const char *lx = lt == PTR ? "pointer" : "integer";
    961 	const char *rx = rt == PTR ? "pointer" : "integer";
    962 	/* illegal combination of %s (%s) and %s (%s), op %s */
    963 	warning(123, lx, type_name(ltp), rx, type_name(rtp), op_name(op));
    964 	return true;
    965 }
    966 
    967 static bool
    968 typeok_quest(tspec_t lt, const tnode_t **rn)
    969 {
    970 	if (!is_scalar(lt)) {
    971 		/* first operand must have scalar type, op ? : */
    972 		error(170);
    973 		return false;
    974 	}
    975 	while ((*rn)->tn_op == CVT)
    976 		*rn = (*rn)->tn_left;
    977 	lint_assert((*rn)->tn_op == COLON);
    978 	return true;
    979 }
    980 
    981 static void
    982 typeok_colon_pointer(const mod_t *mp, const type_t *ltp, const type_t *rtp)
    983 {
    984 	type_t *lstp = ltp->t_subt;
    985 	type_t *rstp = rtp->t_subt;
    986 	tspec_t lst = lstp->t_tspec;
    987 	tspec_t rst = rstp->t_tspec;
    988 
    989 	if ((lst == VOID && rst == FUNC) || (lst == FUNC && rst == VOID)) {
    990 		/* (void *)0 handled above */
    991 		if (sflag)
    992 			/* ANSI C forbids conv. of %s to %s, op %s */
    993 			warning(305, "function pointer", "'void *'",
    994 			    mp->m_name);
    995 		return;
    996 	}
    997 
    998 	if (eqptrtype(lstp, rstp, true))
    999 		return;
   1000 	if (!eqtype(lstp, rstp, true, false, NULL))
   1001 		warn_incompatible_pointers(mp, ltp, rtp);
   1002 }
   1003 
   1004 static bool
   1005 typeok_colon(const mod_t *mp,
   1006 	     const tnode_t *ln, const type_t *ltp, tspec_t lt,
   1007 	     const tnode_t *rn, const type_t *rtp, tspec_t rt)
   1008 {
   1009 
   1010 	if (is_arithmetic(lt) && is_arithmetic(rt))
   1011 		return true;
   1012 	if (lt == BOOL && rt == BOOL)
   1013 		return true;
   1014 
   1015 	if (lt == STRUCT && rt == STRUCT && ltp->t_str == rtp->t_str)
   1016 		return true;
   1017 	if (lt == UNION && rt == UNION && ltp->t_str == rtp->t_str)
   1018 		return true;
   1019 
   1020 	if (lt == PTR && is_null_pointer(rn))
   1021 		return true;
   1022 	if (rt == PTR && is_null_pointer(ln))
   1023 		return true;
   1024 
   1025 	if ((lt == PTR && is_integer(rt)) || (is_integer(lt) && rt == PTR)) {
   1026 		const char *lx = lt == PTR ? "pointer" : "integer";
   1027 		const char *rx = rt == PTR ? "pointer" : "integer";
   1028 		/* illegal combination of %s (%s) and %s (%s), op %s */
   1029 		warning(123, lx, type_name(ltp),
   1030 		    rx, type_name(rtp), mp->m_name);
   1031 		return true;
   1032 	}
   1033 
   1034 	if (lt == VOID || rt == VOID) {
   1035 		if (lt != VOID || rt != VOID)
   1036 			/* incompatible types '%s' and '%s' in conditional */
   1037 			warning(126, type_name(ltp), type_name(rtp));
   1038 		return true;
   1039 	}
   1040 
   1041 	if (lt == PTR && rt == PTR) {
   1042 		typeok_colon_pointer(mp, ltp, rtp);
   1043 		return true;
   1044 	}
   1045 
   1046 	/* incompatible types '%s' and '%s' in conditional */
   1047 	error(126, type_name(ltp), type_name(rtp));
   1048 	return false;
   1049 }
   1050 
   1051 static bool
   1052 typeok_assign(op_t op, const tnode_t *ln, const type_t *ltp, tspec_t lt)
   1053 {
   1054 	if (op == RETURN || op == INIT || op == FARG)
   1055 		return true;
   1056 
   1057 	if (!ln->tn_lvalue) {
   1058 		if (ln->tn_op == CVT && ln->tn_cast &&
   1059 		    ln->tn_left->tn_op == LOAD) {
   1060 			/* a cast does not yield an lvalue */
   1061 			error(163);
   1062 		}
   1063 		/* %soperand of '%s' must be lvalue */
   1064 		error(114, "left ", op_name(op));
   1065 		return false;
   1066 	} else if (ltp->t_const || ((lt == STRUCT || lt == UNION) &&
   1067 				    has_constant_member(ltp))) {
   1068 		if (!tflag)
   1069 			/* %soperand of '%s' must be modifiable lvalue */
   1070 			warning(115, "left ", op_name(op));
   1071 	}
   1072 	return true;
   1073 }
   1074 
   1075 /* Check the types using the information from modtab[]. */
   1076 static bool
   1077 typeok_scalar(op_t op, const mod_t *mp,
   1078 	      const type_t *ltp, tspec_t lt,
   1079 	      const type_t *rtp, tspec_t rt)
   1080 {
   1081 	if (mp->m_takes_bool && lt == BOOL && rt == BOOL)
   1082 		return true;
   1083 	if (mp->m_requires_integer) {
   1084 		if (!is_integer(lt) || (mp->m_binary && !is_integer(rt))) {
   1085 			warn_incompatible_types(op, ltp, lt, rtp, rt);
   1086 			return false;
   1087 		}
   1088 	} else if (mp->m_requires_integer_or_complex) {
   1089 		if ((!is_integer(lt) && !is_complex(lt)) ||
   1090 		    (mp->m_binary && (!is_integer(rt) && !is_complex(rt)))) {
   1091 			warn_incompatible_types(op, ltp, lt, rtp, rt);
   1092 			return false;
   1093 		}
   1094 	} else if (mp->m_requires_scalar) {
   1095 		if (!is_scalar(lt) || (mp->m_binary && !is_scalar(rt))) {
   1096 			warn_incompatible_types(op, ltp, lt, rtp, rt);
   1097 			return false;
   1098 		}
   1099 	} else if (mp->m_requires_arith) {
   1100 		if (!is_arithmetic(lt) ||
   1101 		    (mp->m_binary && !is_arithmetic(rt))) {
   1102 			warn_incompatible_types(op, ltp, lt, rtp, rt);
   1103 			return false;
   1104 		}
   1105 	}
   1106 	return true;
   1107 }
   1108 
   1109 /* Check the types for specific operators and type combinations. */
   1110 static bool
   1111 typeok_op(op_t op, const mod_t *mp, int arg,
   1112 	  const tnode_t *ln, const type_t *ltp, tspec_t lt,
   1113 	  const tnode_t *rn, const type_t *rtp, tspec_t rt)
   1114 {
   1115 	switch (op) {
   1116 	case POINT:
   1117 		/*
   1118 		 * Most errors required by ANSI C are reported in
   1119 		 * struct_or_union_member().
   1120 		 * Here we only must check for totally wrong things.
   1121 		 */
   1122 		if (lt == FUNC || lt == VOID || ltp->t_bitfield ||
   1123 		    ((lt != STRUCT && lt != UNION) && !ln->tn_lvalue)) {
   1124 			/* Without tflag we got already an error */
   1125 			if (tflag)
   1126 				/* unacceptable operand of '%s' */
   1127 				error(111, mp->m_name);
   1128 			return false;
   1129 		}
   1130 		/* Now we have an object we can create a pointer to */
   1131 		break;
   1132 	case ARROW:
   1133 		if (lt != PTR && !(tflag && is_integer(lt))) {
   1134 			/* Without tflag we got already an error */
   1135 			if (tflag)
   1136 				/* unacceptable operand of '%s' */
   1137 				error(111, mp->m_name);
   1138 			return false;
   1139 		}
   1140 		break;
   1141 	case INCAFT:
   1142 	case DECAFT:
   1143 	case INCBEF:
   1144 	case DECBEF:
   1145 		if (!typeok_incdec(op, ln, ltp))
   1146 			return false;
   1147 		break;
   1148 	case ADDR:
   1149 		if (!typeok_address(mp, ln, ltp, lt))
   1150 			return false;
   1151 		break;
   1152 	case INDIR:
   1153 		if (!typeok_star(lt))
   1154 			return false;
   1155 		break;
   1156 	case PLUS:
   1157 		if (!typeok_plus(op, ltp, lt, rtp, rt))
   1158 			return false;
   1159 		break;
   1160 	case MINUS:
   1161 		if (!typeok_minus(op, ltp, lt, rtp, rt))
   1162 			return false;
   1163 		break;
   1164 	case SHR:
   1165 		typeok_shr(mp, ln, lt, rn, rt);
   1166 		goto shift;
   1167 	case SHL:
   1168 		typeok_shl(mp, lt, rt);
   1169 	shift:
   1170 		typeok_shift(lt, rn, rt);
   1171 		break;
   1172 	case EQ:
   1173 	case NE:
   1174 		/*
   1175 		 * Accept some things which are allowed with EQ and NE,
   1176 		 * but not with ordered comparisons.
   1177 		 */
   1178 		if (is_typeok_eq(ln, lt, rn, rt))
   1179 			break;
   1180 		/* FALLTHROUGH */
   1181 	case LT:
   1182 	case GT:
   1183 	case LE:
   1184 	case GE:
   1185 		if (!typeok_ordered_comparison(op, ln, ltp, lt, rn, rtp, rt))
   1186 			return false;
   1187 		break;
   1188 	case QUEST:
   1189 		if (!typeok_quest(lt, &rn))
   1190 			return false;
   1191 		break;
   1192 	case COLON:
   1193 		if (!typeok_colon(mp, ln, ltp, lt, rn, rtp, rt))
   1194 			return false;
   1195 		break;
   1196 	case ASSIGN:
   1197 	case INIT:
   1198 	case FARG:
   1199 	case RETURN:
   1200 		if (!check_assign_types_compatible(op, arg, ln, rn))
   1201 			return false;
   1202 		goto assign;
   1203 	case MULASS:
   1204 	case DIVASS:
   1205 	case MODASS:
   1206 		goto assign;
   1207 	case ADDASS:
   1208 	case SUBASS:
   1209 		/* operands have scalar types (checked above) */
   1210 		if ((lt == PTR && !is_integer(rt)) || rt == PTR) {
   1211 			warn_incompatible_types(op, ltp, lt, rtp, rt);
   1212 			return false;
   1213 		}
   1214 		goto assign;
   1215 	case SHLASS:
   1216 		goto assign;
   1217 	case SHRASS:
   1218 		if (pflag && !is_uinteger(lt) && !(tflag && is_uinteger(rt))) {
   1219 			/* bitwise '%s' on signed value possibly nonportable */
   1220 			warning(117, mp->m_name);
   1221 		}
   1222 		goto assign;
   1223 	case ANDASS:
   1224 	case XORASS:
   1225 	case ORASS:
   1226 		goto assign;
   1227 	assign:
   1228 		if (!typeok_assign(op, ln, ltp, lt))
   1229 			return false;
   1230 		break;
   1231 	case COMMA:
   1232 		if (!modtab[ln->tn_op].m_has_side_effect)
   1233 			check_null_effect(ln);
   1234 		break;
   1235 		/* LINTED206: (enumeration values not handled in switch) */
   1236 	case CON:
   1237 	case CASE:
   1238 	case PUSH:
   1239 	case LOAD:
   1240 	case ICALL:
   1241 	case CVT:
   1242 	case CALL:
   1243 	case FSEL:
   1244 	case STRING:
   1245 	case NAME:
   1246 	case LOGOR:
   1247 	case LOGAND:
   1248 	case BITOR:
   1249 	case BITXOR:
   1250 	case BITAND:
   1251 	case MOD:
   1252 	case DIV:
   1253 	case MULT:
   1254 	case UMINUS:
   1255 	case UPLUS:
   1256 	case DEC:
   1257 	case INC:
   1258 	case COMPL:
   1259 	case NOT:
   1260 	case NOOP:
   1261 	case REAL:
   1262 	case IMAG:
   1263 		break;
   1264 	}
   1265 	return true;
   1266 }
   1267 
   1268 static void
   1269 typeok_enum(op_t op, const mod_t *mp, int arg,
   1270 	    const tnode_t *ln, const type_t *ltp,
   1271 	    const tnode_t *rn, const type_t *rtp)
   1272 {
   1273 	if (mp->m_bad_on_enum &&
   1274 	    (ltp->t_is_enum || (mp->m_binary && rtp->t_is_enum))) {
   1275 		check_bad_enum_operation(op, ln, rn);
   1276 	} else if (mp->m_valid_on_enum &&
   1277 		   (ltp->t_is_enum && rtp != NULL && rtp->t_is_enum)) {
   1278 		check_enum_type_mismatch(op, arg, ln, rn);
   1279 	} else if (mp->m_valid_on_enum &&
   1280 		   (ltp->t_is_enum || (rtp != NULL && rtp->t_is_enum))) {
   1281 		check_enum_int_mismatch(op, arg, ln, rn);
   1282 	}
   1283 }
   1284 
   1285 /* Perform most type checks. Return whether the types are ok. */
   1286 bool
   1287 typeok(op_t op, int arg, const tnode_t *ln, const tnode_t *rn)
   1288 {
   1289 	const mod_t *mp;
   1290 	tspec_t	lt, rt;
   1291 	type_t	*ltp, *rtp;
   1292 
   1293 	mp = &modtab[op];
   1294 
   1295 	lint_assert((ltp = ln->tn_type) != NULL);
   1296 	lt = ltp->t_tspec;
   1297 
   1298 	if (mp->m_binary) {
   1299 		lint_assert((rtp = rn->tn_type) != NULL);
   1300 		rt = rtp->t_tspec;
   1301 	} else {
   1302 		rtp = NULL;
   1303 		rt = NOTSPEC;
   1304 	}
   1305 
   1306 	if (Tflag && !typeok_scalar_strict_bool(op, mp, arg, ln, rn))
   1307 		return false;
   1308 	if (!typeok_scalar(op, mp, ltp, lt, rtp, rt))
   1309 		return false;
   1310 
   1311 	if (!typeok_op(op, mp, arg, ln, ltp, lt, rn, rtp, rt))
   1312 		return false;
   1313 
   1314 	typeok_enum(op, mp, arg, ln, ltp, rn, rtp);
   1315 	return true;
   1316 }
   1317 
   1318 static void
   1319 check_pointer_comparison(op_t op, const tnode_t *ln, const tnode_t *rn)
   1320 {
   1321 	type_t	*ltp, *rtp;
   1322 	tspec_t	lst, rst;
   1323 	const	char *lsts, *rsts;
   1324 
   1325 	lst = (ltp = ln->tn_type)->t_subt->t_tspec;
   1326 	rst = (rtp = rn->tn_type)->t_subt->t_tspec;
   1327 
   1328 	if (lst == VOID || rst == VOID) {
   1329 		if (sflag && (lst == FUNC || rst == FUNC)) {
   1330 			/* (void *)0 already handled in typeok() */
   1331 			*(lst == FUNC ? &lsts : &rsts) = "function pointer";
   1332 			*(lst == VOID ? &lsts : &rsts) = "'void *'";
   1333 			/* ANSI C forbids comparison of %s with %s */
   1334 			warning(274, lsts, rsts);
   1335 		}
   1336 		return;
   1337 	}
   1338 
   1339 	if (!eqtype(ltp->t_subt, rtp->t_subt, true, false, NULL)) {
   1340 		warn_incompatible_pointers(&modtab[op], ltp, rtp);
   1341 		return;
   1342 	}
   1343 
   1344 	if (lst == FUNC && rst == FUNC) {
   1345 		if (sflag && op != EQ && op != NE)
   1346 			/* ANSI C forbids ordered comparisons of ... */
   1347 			warning(125);
   1348 	}
   1349 }
   1350 
   1351 static bool
   1352 is_direct_function_call(const tnode_t *tn, const char **out_name)
   1353 {
   1354 
   1355 	if (!(tn->tn_op == CALL &&
   1356 	      tn->tn_left->tn_op == ADDR &&
   1357 	      tn->tn_left->tn_left->tn_op == NAME))
   1358 		return false;
   1359 
   1360 	*out_name = tn->tn_left->tn_left->tn_sym->s_name;
   1361 	return true;
   1362 }
   1363 
   1364 static bool
   1365 is_unconst_function(const char *name)
   1366 {
   1367 
   1368 	return strcmp(name, "memchr") == 0 ||
   1369 	       strcmp(name, "strchr") == 0 ||
   1370 	       strcmp(name, "strpbrk") == 0 ||
   1371 	       strcmp(name, "strrchr") == 0 ||
   1372 	       strcmp(name, "strstr") == 0;
   1373 }
   1374 
   1375 static bool
   1376 is_const_char_pointer(const tnode_t *tn)
   1377 {
   1378 	const type_t *tp;
   1379 
   1380 	/*
   1381 	 * For traditional reasons, C99 6.4.5p5 defines that string literals
   1382 	 * have type 'char[]'.  They are often implicitly converted to
   1383 	 * 'char *', for example when they are passed as function arguments.
   1384 	 *
   1385 	 * C99 6.4.5p6 further defines that modifying a string that is
   1386 	 * constructed from a string literal invokes undefined behavior.
   1387 	 *
   1388 	 * Out of these reasons, string literals are treated as 'effectively
   1389 	 * const' here.
   1390 	 */
   1391 	if (tn->tn_op == CVT &&
   1392 	    tn->tn_left->tn_op == ADDR &&
   1393 	    tn->tn_left->tn_left->tn_op == STRING)
   1394 		return true;
   1395 
   1396 	tp = before_conversion(tn)->tn_type;
   1397 	return tp->t_tspec == PTR &&
   1398 	       tp->t_subt->t_tspec == CHAR &&
   1399 	       tp->t_subt->t_const;
   1400 }
   1401 
   1402 static bool
   1403 is_first_arg_const(const tnode_t *tn)
   1404 {
   1405 	const tnode_t *an;
   1406 
   1407 	an = tn->tn_right;
   1408 	if (an == NULL)
   1409 		return false;
   1410 
   1411 	while (an->tn_right != NULL)
   1412 		an = an->tn_right;
   1413 	return is_const_char_pointer(an->tn_left);
   1414 }
   1415 
   1416 static void
   1417 check_unconst_function(const type_t *lstp,
   1418 		       const tnode_t *rn, const type_t *rstp)
   1419 {
   1420 	const char *function_name;
   1421 
   1422 	if (lstp->t_tspec == CHAR && !lstp->t_const &&
   1423 	    is_direct_function_call(rn, &function_name) &&
   1424 	    is_unconst_function(function_name) &&
   1425 	    is_first_arg_const(rn)) {
   1426 		/* call to '%s' effectively discards 'const' from argument */
   1427 		warning(346, function_name);
   1428 	}
   1429 }
   1430 
   1431 /*
   1432  * Checks type compatibility for ASSIGN, INIT, FARG and RETURN
   1433  * and prints warnings/errors if necessary.
   1434  * If the types are (almost) compatible, 1 is returned, otherwise 0.
   1435  */
   1436 static bool
   1437 check_assign_types_compatible(op_t op, int arg,
   1438 			      const tnode_t *ln, const tnode_t *rn)
   1439 {
   1440 	tspec_t	lt, rt, lst = NOTSPEC, rst = NOTSPEC;
   1441 	type_t	*ltp, *rtp, *lstp = NULL, *rstp = NULL;
   1442 	const mod_t *mp;
   1443 	const	char *lts, *rts;
   1444 
   1445 	if ((lt = (ltp = ln->tn_type)->t_tspec) == PTR)
   1446 		lst = (lstp = ltp->t_subt)->t_tspec;
   1447 	if ((rt = (rtp = rn->tn_type)->t_tspec) == PTR)
   1448 		rst = (rstp = rtp->t_subt)->t_tspec;
   1449 	mp = &modtab[op];
   1450 
   1451 	if (lt == BOOL && is_scalar(rt))	/* C99 6.3.1.2 */
   1452 		return true;
   1453 
   1454 	if (is_arithmetic(lt) && (is_arithmetic(rt) || rt == BOOL))
   1455 		return true;
   1456 
   1457 	if ((lt == STRUCT || lt == UNION) && (rt == STRUCT || rt == UNION))
   1458 		/* both are struct or union */
   1459 		return ltp->t_str == rtp->t_str;
   1460 
   1461 	/* a null pointer may be assigned to any pointer */
   1462 	if (lt == PTR && is_null_pointer(rn))
   1463 		return true;
   1464 
   1465 	if (lt == PTR && rt == PTR && (lst == VOID || rst == VOID)) {
   1466 		/* two pointers, at least one pointer to void */
   1467 		if (sflag && (lst == FUNC || rst == FUNC)) {
   1468 			/* comb. of ptr to func and ptr to void */
   1469 			*(lst == FUNC ? &lts : &rts) = "function pointer";
   1470 			*(lst == VOID ? &lts : &rts) = "'void *'";
   1471 			switch (op) {
   1472 			case INIT:
   1473 			case RETURN:
   1474 				/* ANSI C forbids conversion of %s to %s */
   1475 				warning(303, rts, lts);
   1476 				break;
   1477 			case FARG:
   1478 				/* ANSI C forbids conv. of %s to %s, arg #%d */
   1479 				warning(304, rts, lts, arg);
   1480 				break;
   1481 			default:
   1482 				/* ANSI C forbids conv. of %s to %s, op %s */
   1483 				warning(305, rts, lts, mp->m_name);
   1484 				break;
   1485 			}
   1486 		}
   1487 	}
   1488 
   1489 	if (lt == PTR && rt == PTR && (lst == VOID || rst == VOID ||
   1490 				       eqtype(lstp, rstp, true, false, NULL))) {
   1491 		/* compatible pointer types (qualifiers ignored) */
   1492 		if (!tflag &&
   1493 		    ((!lstp->t_const && rstp->t_const) ||
   1494 		     (!lstp->t_volatile && rstp->t_volatile))) {
   1495 			/* left side has not all qualifiers of right */
   1496 			switch (op) {
   1497 			case INIT:
   1498 			case RETURN:
   1499 				/* incompatible pointer types (%s != %s) */
   1500 				warning(182, type_name(lstp), type_name(rstp));
   1501 				break;
   1502 			case FARG:
   1503 				/* converting '%s' to incompatible '%s' ... */
   1504 				warning(153,
   1505 				    type_name(rtp), type_name(ltp), arg);
   1506 				break;
   1507 			default:
   1508 				/* operands have incompatible pointer type... */
   1509 				warning(128, mp->m_name,
   1510 				    type_name(lstp), type_name(rstp));
   1511 				break;
   1512 			}
   1513 		}
   1514 
   1515 		if (!tflag)
   1516 			check_unconst_function(lstp, rn, rstp);
   1517 
   1518 		return true;
   1519 	}
   1520 
   1521 	if ((lt == PTR && is_integer(rt)) || (is_integer(lt) && rt == PTR)) {
   1522 		const char *lx = lt == PTR ? "pointer" : "integer";
   1523 		const char *rx = rt == PTR ? "pointer" : "integer";
   1524 
   1525 		switch (op) {
   1526 		case INIT:
   1527 		case RETURN:
   1528 			/* illegal combination of %s (%s) and %s (%s) */
   1529 			warning(183, lx, type_name(ltp), rx, type_name(rtp));
   1530 			break;
   1531 		case FARG:
   1532 			/* illegal comb. of %s (%s) and %s (%s), arg #%d */
   1533 			warning(154,
   1534 			    lx, type_name(ltp), rx, type_name(rtp), arg);
   1535 			break;
   1536 		default:
   1537 			/* illegal combination of %s (%s) and %s (%s), op %s */
   1538 			warning(123,
   1539 			    lx, type_name(ltp), rx, type_name(rtp), mp->m_name);
   1540 			break;
   1541 		}
   1542 		return true;
   1543 	}
   1544 
   1545 	if (lt == PTR && rt == PTR) {
   1546 		switch (op) {
   1547 		case RETURN:
   1548 			warn_incompatible_pointers(NULL, ltp, rtp);
   1549 			break;
   1550 		case FARG:
   1551 			/* converting '%s' to incompatible '%s' for ... */
   1552 			warning(153, type_name(rtp), type_name(ltp), arg);
   1553 			break;
   1554 		default:
   1555 			warn_incompatible_pointers(mp, ltp, rtp);
   1556 			break;
   1557 		}
   1558 		return true;
   1559 	}
   1560 
   1561 	switch (op) {
   1562 	case INIT:
   1563 		/* cannot initialize '%s' from '%s' */
   1564 		error(185, type_name(ltp), type_name(rtp));
   1565 		break;
   1566 	case RETURN:
   1567 		/* return value type mismatch (%s) and (%s) */
   1568 		error(211, type_name(ltp), type_name(rtp));
   1569 		break;
   1570 	case FARG:
   1571 		/* passing '%s' to incompatible '%s', arg #%d */
   1572 		warning(155, type_name(rtp), type_name(ltp), arg);
   1573 		break;
   1574 	default:
   1575 		warn_incompatible_types(op, ltp, lt, rtp, rt);
   1576 		break;
   1577 	}
   1578 
   1579 	return false;
   1580 }
   1581 
   1582 /* Prints a warning if a strange operator is used on an enum type. */
   1583 static void
   1584 check_bad_enum_operation(op_t op, const tnode_t *ln, const tnode_t *rn)
   1585 {
   1586 
   1587 	if (!eflag)
   1588 		return;
   1589 
   1590 	/*
   1591 	 * Enum as offset to a pointer is an exception (otherwise enums
   1592 	 * could not be used as array indices).
   1593 	 */
   1594 	if (op == PLUS &&
   1595 	    ((ln->tn_type->t_is_enum && rn->tn_type->t_tspec == PTR) ||
   1596 	     (rn->tn_type->t_is_enum && ln->tn_type->t_tspec == PTR))) {
   1597 		return;
   1598 	}
   1599 
   1600 	/* dubious operation on enum, op %s */
   1601 	warning(241, op_name(op));
   1602 }
   1603 
   1604 /*
   1605  * Prints a warning if an operator is applied to two different enum types.
   1606  */
   1607 static void
   1608 check_enum_type_mismatch(op_t op, int arg, const tnode_t *ln, const tnode_t *rn)
   1609 {
   1610 	const mod_t *mp;
   1611 
   1612 	mp = &modtab[op];
   1613 
   1614 	if (ln->tn_type->t_enum != rn->tn_type->t_enum) {
   1615 		switch (op) {
   1616 		case INIT:
   1617 			/* enum type mismatch between '%s' and '%s' in ... */
   1618 			warning(210,
   1619 			    type_name(ln->tn_type), type_name(rn->tn_type));
   1620 			break;
   1621 		case FARG:
   1622 			/* enum type mismatch, arg #%d (%s != %s) */
   1623 			warning(156, arg,
   1624 			    type_name(ln->tn_type), type_name(rn->tn_type));
   1625 			break;
   1626 		case RETURN:
   1627 			/* return value type mismatch (%s) and (%s) */
   1628 			warning(211,
   1629 			    type_name(ln->tn_type), type_name(rn->tn_type));
   1630 			break;
   1631 		default:
   1632 			/* enum type mismatch: '%s' '%s' '%s' */
   1633 			warning(130, type_name(ln->tn_type), mp->m_name,
   1634 			    type_name(rn->tn_type));
   1635 			break;
   1636 		}
   1637 	} else if (Pflag && mp->m_comparison && op != EQ && op != NE) {
   1638 		if (eflag)
   1639 			/* dubious comparison of enums, op %s */
   1640 			warning(243, mp->m_name);
   1641 	}
   1642 }
   1643 
   1644 /* Prints a warning if the operands mix between enum and integer. */
   1645 static void
   1646 check_enum_int_mismatch(op_t op, int arg, const tnode_t *ln, const tnode_t *rn)
   1647 {
   1648 
   1649 	if (!eflag)
   1650 		return;
   1651 
   1652 	switch (op) {
   1653 	case INIT:
   1654 		/*
   1655 		 * Initialization with 0 is allowed. Otherwise, all implicit
   1656 		 * initializations would need to be warned upon as well.
   1657 		 */
   1658 		if (!rn->tn_type->t_is_enum && rn->tn_op == CON &&
   1659 		    is_integer(rn->tn_type->t_tspec) &&
   1660 		    rn->tn_val->v_quad == 0) {
   1661 			return;
   1662 		}
   1663 		/* initialization of '%s' with '%s' */
   1664 		warning(277, type_name(ln->tn_type), type_name(rn->tn_type));
   1665 		break;
   1666 	case FARG:
   1667 		/* combination of '%s' and '%s', arg #%d */
   1668 		warning(278,
   1669 		    type_name(ln->tn_type), type_name(rn->tn_type), arg);
   1670 		break;
   1671 	case RETURN:
   1672 		/* combination of '%s' and '%s' in return */
   1673 		warning(279, type_name(ln->tn_type), type_name(rn->tn_type));
   1674 		break;
   1675 	default:
   1676 		/* combination of '%s' and '%s', op %s */
   1677 		warning(242, type_name(ln->tn_type), type_name(rn->tn_type),
   1678 		    op_name(op));
   1679 		break;
   1680 	}
   1681 }
   1682 
   1683 /*
   1684  * Build and initialize a new node.
   1685  */
   1686 static tnode_t *
   1687 new_tnode(op_t op, type_t *type, tnode_t *ln, tnode_t *rn)
   1688 {
   1689 	tnode_t	*ntn;
   1690 	tspec_t	t;
   1691 #if 0 /* not yet */
   1692 	size_t l;
   1693 	uint64_t rnum;
   1694 #endif
   1695 
   1696 	ntn = expr_zalloc_tnode();
   1697 
   1698 	ntn->tn_op = op;
   1699 	ntn->tn_type = type;
   1700 	ntn->tn_relaxed = ln->tn_relaxed || (rn != NULL && rn->tn_relaxed);
   1701 	ntn->tn_left = ln;
   1702 	ntn->tn_right = rn;
   1703 
   1704 	switch (op) {
   1705 #if 0 /* not yet */
   1706 	case SHR:
   1707 		if (rn->tn_op != CON)
   1708 			break;
   1709 		rnum = rn->tn_val->v_quad;
   1710 		l = type_size_in_bits(ln->tn_type) / CHAR_SIZE;
   1711 		t = ln->tn_type->t_tspec;
   1712 		switch (l) {
   1713 		case 8:
   1714 			if (rnum >= 56)
   1715 				t = UCHAR;
   1716 			else if (rnum >= 48)
   1717 				t = USHORT;
   1718 			else if (rnum >= 32)
   1719 				t = UINT;
   1720 			break;
   1721 		case 4:
   1722 			if (rnum >= 24)
   1723 				t = UCHAR;
   1724 			else if (rnum >= 16)
   1725 				t = USHORT;
   1726 			break;
   1727 		case 2:
   1728 			if (rnum >= 8)
   1729 				t = UCHAR;
   1730 			break;
   1731 		default:
   1732 			break;
   1733 		}
   1734 		if (t != ln->tn_type->t_tspec)
   1735 			ntn->tn_type->t_tspec = t;
   1736 		break;
   1737 #endif
   1738 	case INDIR:
   1739 	case FSEL:
   1740 		lint_assert(ln->tn_type->t_tspec == PTR);
   1741 		t = ln->tn_type->t_subt->t_tspec;
   1742 		if (t != FUNC && t != VOID)
   1743 			ntn->tn_lvalue = true;
   1744 		break;
   1745 	default:
   1746 		break;
   1747 	}
   1748 
   1749 	return ntn;
   1750 }
   1751 
   1752 /*
   1753  * Performs the "integer promotions" (C99 6.3.1.1p2), which convert small
   1754  * integer types to either int or unsigned int.
   1755  *
   1756  * If tflag is set or the operand is a function argument with no type
   1757  * information (no prototype or variable # of args), converts float to double.
   1758  */
   1759 tnode_t *
   1760 promote(op_t op, bool farg, tnode_t *tn)
   1761 {
   1762 	tspec_t	t;
   1763 	type_t	*ntp;
   1764 	u_int	len;
   1765 
   1766 	t = tn->tn_type->t_tspec;
   1767 
   1768 	if (!is_arithmetic(t))
   1769 		return tn;
   1770 
   1771 	if (!tflag) {
   1772 		/*
   1773 		 * C99 6.3.1.1p2 requires for types with lower rank than int
   1774 		 * that "If an int can represent all the values of the
   1775 		 * original type, the value is converted to an int; otherwise
   1776 		 * it is converted to an unsigned int", and that "All other
   1777 		 * types are unchanged by the integer promotions".
   1778 		 */
   1779 		if (tn->tn_type->t_bitfield) {
   1780 			len = tn->tn_type->t_flen;
   1781 			if (len < size_in_bits(INT)) {
   1782 				t = INT;
   1783 			} else if (len == size_in_bits(INT)) {
   1784 				t = is_uinteger(t) ? UINT : INT;
   1785 			}
   1786 		} else if (t == CHAR || t == UCHAR || t == SCHAR) {
   1787 			t = (size_in_bits(CHAR) < size_in_bits(INT)
   1788 			     || t != UCHAR) ? INT : UINT;
   1789 		} else if (t == SHORT || t == USHORT) {
   1790 			t = (size_in_bits(SHORT) < size_in_bits(INT)
   1791 			     || t == SHORT) ? INT : UINT;
   1792 		} else if (t == ENUM) {
   1793 			t = INT;
   1794 		} else if (farg && t == FLOAT) {
   1795 			t = DOUBLE;
   1796 		}
   1797 	} else {
   1798 		/*
   1799 		 * In traditional C, keep unsigned and promote FLOAT
   1800 		 * to DOUBLE.
   1801 		 */
   1802 		if (t == UCHAR || t == USHORT) {
   1803 			t = UINT;
   1804 		} else if (t == CHAR || t == SCHAR || t == SHORT) {
   1805 			t = INT;
   1806 		} else if (t == FLOAT) {
   1807 			t = DOUBLE;
   1808 		} else if (t == ENUM) {
   1809 			t = INT;
   1810 		}
   1811 	}
   1812 
   1813 	if (t != tn->tn_type->t_tspec) {
   1814 		ntp = expr_dup_type(tn->tn_type);
   1815 		ntp->t_tspec = t;
   1816 		/*
   1817 		 * Keep t_is_enum even though t_tspec gets converted from
   1818 		 * ENUM to INT, so we are later able to check compatibility
   1819 		 * of enum types.
   1820 		 */
   1821 		tn = convert(op, 0, ntp, tn);
   1822 	}
   1823 
   1824 	return tn;
   1825 }
   1826 
   1827 /*
   1828  * Apply the "usual arithmetic conversions" (C99 6.3.1.8).
   1829  *
   1830  * This gives both operands the same type.
   1831  * This is done in different ways for traditional C and C90.
   1832  */
   1833 static void
   1834 balance(op_t op, tnode_t **lnp, tnode_t **rnp)
   1835 {
   1836 	tspec_t	lt, rt, t;
   1837 	int	i;
   1838 	bool	u;
   1839 	type_t	*ntp;
   1840 	static const tspec_t tl[] = {
   1841 		LDOUBLE, DOUBLE, FLOAT,
   1842 #ifdef INT128_SIZE
   1843 		UINT128, INT128,
   1844 #endif
   1845 		UQUAD, QUAD,
   1846 		ULONG, LONG,
   1847 		UINT, INT,
   1848 	};
   1849 
   1850 	lt = (*lnp)->tn_type->t_tspec;
   1851 	rt = (*rnp)->tn_type->t_tspec;
   1852 
   1853 	if (!is_arithmetic(lt) || !is_arithmetic(rt))
   1854 		return;
   1855 
   1856 	if (!tflag) {
   1857 		if (lt == rt) {
   1858 			t = lt;
   1859 		} else if (lt == LCOMPLEX || rt == LCOMPLEX) {
   1860 			t = LCOMPLEX;
   1861 		} else if (lt == DCOMPLEX || rt == DCOMPLEX) {
   1862 			t = DCOMPLEX;
   1863 		} else if (lt == FCOMPLEX || rt == FCOMPLEX) {
   1864 			t = FCOMPLEX;
   1865 		} else if (lt == LDOUBLE || rt == LDOUBLE) {
   1866 			t = LDOUBLE;
   1867 		} else if (lt == DOUBLE || rt == DOUBLE) {
   1868 			t = DOUBLE;
   1869 		} else if (lt == FLOAT || rt == FLOAT) {
   1870 			t = FLOAT;
   1871 		} else {
   1872 			/*
   1873 			 * If type A has more bits than type B it should
   1874 			 * be able to hold all possible values of type B.
   1875 			 */
   1876 			if (size_in_bits(lt) > size_in_bits(rt)) {
   1877 				t = lt;
   1878 			} else if (size_in_bits(lt) < size_in_bits(rt)) {
   1879 				t = rt;
   1880 			} else {
   1881 				for (i = 3; tl[i] != INT; i++) {
   1882 					if (tl[i] == lt || tl[i] == rt)
   1883 						break;
   1884 				}
   1885 				if ((is_uinteger(lt) || is_uinteger(rt)) &&
   1886 				    !is_uinteger(tl[i])) {
   1887 					i--;
   1888 				}
   1889 				t = tl[i];
   1890 			}
   1891 		}
   1892 	} else {
   1893 		/* Keep unsigned in traditional C */
   1894 		u = is_uinteger(lt) || is_uinteger(rt);
   1895 		for (i = 0; tl[i] != INT; i++) {
   1896 			if (lt == tl[i] || rt == tl[i])
   1897 				break;
   1898 		}
   1899 		t = tl[i];
   1900 		if (u && is_integer(t) && !is_uinteger(t))
   1901 			t = unsigned_type(t);
   1902 	}
   1903 
   1904 	if (t != lt) {
   1905 		ntp = expr_dup_type((*lnp)->tn_type);
   1906 		ntp->t_tspec = t;
   1907 		*lnp = convert(op, 0, ntp, *lnp);
   1908 	}
   1909 	if (t != rt) {
   1910 		ntp = expr_dup_type((*rnp)->tn_type);
   1911 		ntp->t_tspec = t;
   1912 		*rnp = convert(op, 0, ntp, *rnp);
   1913 	}
   1914 }
   1915 
   1916 /*
   1917  * Insert a conversion operator, which converts the type of the node
   1918  * to another given type.
   1919  * If op is FARG, arg is the number of the argument (used for warnings).
   1920  */
   1921 tnode_t *
   1922 convert(op_t op, int arg, type_t *tp, tnode_t *tn)
   1923 {
   1924 	tnode_t	*ntn;
   1925 	tspec_t	nt, ot;
   1926 
   1927 	nt = tp->t_tspec;
   1928 	ot = tn->tn_type->t_tspec;
   1929 
   1930 	if (!tflag && !sflag && op == FARG)
   1931 		check_prototype_conversion(arg, nt, ot, tp, tn);
   1932 	if (is_integer(nt) && is_integer(ot)) {
   1933 		check_integer_conversion(op, arg, nt, ot, tp, tn);
   1934 	} else if (nt == PTR && is_null_pointer(tn)) {
   1935 		/* a null pointer may be assigned to any pointer. */
   1936 	} else if (is_integer(nt) && nt != BOOL && ot == PTR) {
   1937 		check_pointer_integer_conversion(op, nt, tp, tn);
   1938 	} else if (nt == PTR && ot == PTR && op == CVT) {
   1939 		check_pointer_conversion(tn, tp);
   1940 	}
   1941 
   1942 	ntn = expr_zalloc_tnode();
   1943 	ntn->tn_op = CVT;
   1944 	ntn->tn_type = tp;
   1945 	ntn->tn_cast = op == CVT;
   1946 	ntn->tn_relaxed |= tn->tn_relaxed;
   1947 	ntn->tn_right = NULL;
   1948 	if (tn->tn_op != CON || nt == VOID) {
   1949 		ntn->tn_left = tn;
   1950 	} else {
   1951 		ntn->tn_op = CON;
   1952 		ntn->tn_val = expr_zalloc(sizeof(*ntn->tn_val));
   1953 		convert_constant(op, arg, ntn->tn_type, ntn->tn_val,
   1954 		    tn->tn_val);
   1955 	}
   1956 
   1957 	return ntn;
   1958 }
   1959 
   1960 /*
   1961  * Print a warning if a prototype causes a type conversion that is
   1962  * different from what would happen to the same argument in the
   1963  * absence of a prototype.
   1964  *
   1965  * Errors/warnings about illegal type combinations are already printed
   1966  * in check_assign_types_compatible().
   1967  */
   1968 static void
   1969 check_prototype_conversion(int arg, tspec_t nt, tspec_t ot, type_t *tp,
   1970 			   tnode_t *tn)
   1971 {
   1972 	tnode_t	*ptn;
   1973 
   1974 	if (!is_arithmetic(nt) || !is_arithmetic(ot))
   1975 		return;
   1976 
   1977 	/*
   1978 	 * If the type of the formal parameter is char/short, a warning
   1979 	 * would be useless, because functions declared the old style
   1980 	 * can't expect char/short arguments.
   1981 	 */
   1982 	/* XXX: what about SCHAR? */
   1983 	if (nt == CHAR || nt == UCHAR || nt == SHORT || nt == USHORT)
   1984 		return;
   1985 
   1986 	/* get default promotion */
   1987 	ptn = promote(NOOP, true, tn);
   1988 	ot = ptn->tn_type->t_tspec;
   1989 
   1990 	/* return if types are the same with and without prototype */
   1991 	if (nt == ot || (nt == ENUM && ot == INT))
   1992 		return;
   1993 
   1994 	if (is_floating(nt) != is_floating(ot) ||
   1995 	    portable_size_in_bits(nt) != portable_size_in_bits(ot)) {
   1996 		/* representation and/or width change */
   1997 		if (!is_integer(ot) ||
   1998 		    portable_size_in_bits(ot) > portable_size_in_bits(INT)) {
   1999 			/* argument #%d is converted from '%s' to '%s' ... */
   2000 			warning(259,
   2001 			    arg, type_name(tn->tn_type), type_name(tp));
   2002 		}
   2003 	} else if (hflag) {
   2004 		/*
   2005 		 * they differ in sign or base type (char, short, int,
   2006 		 * long, long long, float, double, long double)
   2007 		 *
   2008 		 * if they differ only in sign and the argument is a constant
   2009 		 * and the msb of the argument is not set, print no warning
   2010 		 */
   2011 		if (ptn->tn_op == CON && is_integer(nt) &&
   2012 		    signed_type(nt) == signed_type(ot) &&
   2013 		    !msb(ptn->tn_val->v_quad, ot, -1)) {
   2014 			/* ok */
   2015 		} else {
   2016 			/* argument #%d is converted from '%s' to '%s' ... */
   2017 			warning(259,
   2018 			    arg, type_name(tn->tn_type), type_name(tp));
   2019 		}
   2020 	}
   2021 }
   2022 
   2023 /*
   2024  * Print warnings for conversions of integer types which may cause problems.
   2025  */
   2026 static void
   2027 check_integer_conversion(op_t op, int arg, tspec_t nt, tspec_t ot, type_t *tp,
   2028 			 tnode_t *tn)
   2029 {
   2030 
   2031 	if (tn->tn_op == CON)
   2032 		return;
   2033 
   2034 	if (op == CVT)
   2035 		return;
   2036 
   2037 	if (Sflag && nt == BOOL)
   2038 		return;		/* See C99 6.3.1.2 */
   2039 
   2040 	if (Pflag && portable_size_in_bits(nt) > portable_size_in_bits(ot) &&
   2041 	    is_uinteger(nt) != is_uinteger(ot)) {
   2042 		if (aflag > 0 && pflag) {
   2043 			if (op == FARG) {
   2044 				/* conversion to '%s' may sign-extend ... */
   2045 				warning(297, type_name(tp), arg);
   2046 			} else {
   2047 				/* conversion to '%s' may sign-extend ... */
   2048 				warning(131, type_name(tp));
   2049 			}
   2050 		}
   2051 	}
   2052 
   2053 	if (Pflag && portable_size_in_bits(nt) > portable_size_in_bits(ot)) {
   2054 		switch (tn->tn_op) {
   2055 		case PLUS:
   2056 		case MINUS:
   2057 		case MULT:
   2058 		case SHL:
   2059 			/* suggest cast from '%s' to '%s' on op %s to ... */
   2060 			warning(324, type_name(gettyp(ot)), type_name(tp),
   2061 			    op_name(tn->tn_op));
   2062 			break;
   2063 		default:
   2064 			break;
   2065 		}
   2066 	}
   2067 
   2068 	if (portable_size_in_bits(nt) < portable_size_in_bits(ot) &&
   2069 	    (ot == LONG || ot == ULONG || ot == QUAD || ot == UQUAD ||
   2070 	     aflag > 1)) {
   2071 		/* conversion from '%s' may lose accuracy */
   2072 		if (aflag > 0) {
   2073 			if (op == FARG) {
   2074 				/* conv. from '%s' to '%s' may lose ... */
   2075 				warning(298,
   2076 				    type_name(tn->tn_type), type_name(tp), arg);
   2077 			} else {
   2078 				/* conv. from '%s' to '%s' may lose accuracy */
   2079 				warning(132,
   2080 				    type_name(tn->tn_type), type_name(tp));
   2081 			}
   2082 		}
   2083 	}
   2084 }
   2085 
   2086 /*
   2087  * Print warnings for dubious conversions of pointer to integer.
   2088  */
   2089 static void
   2090 check_pointer_integer_conversion(op_t op, tspec_t nt, type_t *tp, tnode_t *tn)
   2091 {
   2092 
   2093 	if (tn->tn_op == CON)
   2094 		return;
   2095 	if (op != CVT)
   2096 		return;		/* We got already an error. */
   2097 	if (portable_size_in_bits(nt) >= portable_size_in_bits(PTR))
   2098 		return;
   2099 
   2100 	if (pflag && size_in_bits(nt) >= size_in_bits(PTR)) {
   2101 		/* conversion of pointer to '%s' may lose bits */
   2102 		warning(134, type_name(tp));
   2103 	} else {
   2104 		/* conversion of pointer to '%s' loses bits */
   2105 		warning(133, type_name(tp));
   2106 	}
   2107 }
   2108 
   2109 static bool
   2110 should_warn_about_pointer_cast(const type_t *nstp, tspec_t nst,
   2111 			       const type_t *ostp, tspec_t ost)
   2112 {
   2113 	/*
   2114 	 * Casting a pointer to 'struct S' to a pointer to another struct that
   2115 	 * has 'struct S' as its first member is ok, see msg_247.c, 'struct
   2116 	 * counter'.
   2117 	 */
   2118 	if (nst == STRUCT && ost == STRUCT &&
   2119 	    nstp->t_str->sou_first_member != NULL &&
   2120 	    nstp->t_str->sou_first_member->s_type == ostp)
   2121 		return false;
   2122 
   2123 	if (is_incomplete(nstp) || is_incomplete(ostp))
   2124 		return false;
   2125 
   2126 	if ((nst == STRUCT || nst == UNION) && nstp->t_str != ostp->t_str)
   2127 		return true;
   2128 
   2129 	if (nst == CHAR || nst == UCHAR)
   2130 		return false;	/* for the sake of traditional C code */
   2131 	if (ost == CHAR || ost == UCHAR)
   2132 		return false;	/* for the sake of traditional C code */
   2133 
   2134 	return portable_size_in_bits(nst) != portable_size_in_bits(ost);
   2135 }
   2136 
   2137 /*
   2138  * Warn about questionable pointer conversions.
   2139  */
   2140 static void
   2141 check_pointer_conversion(tnode_t *tn, type_t *ntp)
   2142 {
   2143 	const type_t *nstp, *otp, *ostp;
   2144 	tspec_t nst, ost;
   2145 	const char *nts, *ots;
   2146 
   2147 	nstp = ntp->t_subt;
   2148 	otp = tn->tn_type;
   2149 	ostp = otp->t_subt;
   2150 	nst = nstp->t_tspec;
   2151 	ost = ostp->t_tspec;
   2152 
   2153 	if (nst == VOID || ost == VOID) {
   2154 		if (sflag && (nst == FUNC || ost == FUNC)) {
   2155 			/* null pointers are already handled in convert() */
   2156 			*(nst == FUNC ? &nts : &ots) = "function pointer";
   2157 			*(nst == VOID ? &nts : &ots) = "'void *'";
   2158 			/* ANSI C forbids conversion of %s to %s */
   2159 			warning(303, ots, nts);
   2160 		}
   2161 		return;
   2162 	} else if (nst == FUNC && ost == FUNC) {
   2163 		return;
   2164 	} else if (nst == FUNC || ost == FUNC) {
   2165 		/* converting '%s' to '%s' is questionable */
   2166 		warning(229, type_name(otp), type_name(ntp));
   2167 		return;
   2168 	}
   2169 
   2170 	if (hflag && alignment_in_bits(nstp) > alignment_in_bits(ostp) &&
   2171 	    ost != CHAR && ost != UCHAR &&
   2172 	    !is_incomplete(ostp)) {
   2173 		/* converting '%s' to '%s' may cause alignment problem */
   2174 		warning(135, type_name(otp), type_name(ntp));
   2175 	}
   2176 
   2177 	if (cflag && should_warn_about_pointer_cast(nstp, nst, ostp, ost)) {
   2178 		/* pointer cast from '%s' to '%s' may be troublesome */
   2179 		warning(247, type_name(otp), type_name(ntp));
   2180 	}
   2181 }
   2182 
   2183 static void
   2184 convert_constant_floating(op_t op, int arg, tspec_t ot, const type_t *tp,
   2185 			  tspec_t nt, val_t *v, val_t *nv)
   2186 {
   2187 	ldbl_t	max = 0.0, min = 0.0;
   2188 
   2189 	switch (nt) {
   2190 	case CHAR:
   2191 		max = TARG_CHAR_MAX;	min = TARG_CHAR_MIN;	break;
   2192 	case UCHAR:
   2193 		max = TARG_UCHAR_MAX;	min = 0;		break;
   2194 	case SCHAR:
   2195 		max = TARG_SCHAR_MAX;	min = TARG_SCHAR_MIN;	break;
   2196 	case SHORT:
   2197 		max = TARG_SHRT_MAX;	min = TARG_SHRT_MIN;	break;
   2198 	case USHORT:
   2199 		max = TARG_USHRT_MAX;	min = 0;		break;
   2200 	case ENUM:
   2201 	case INT:
   2202 		max = TARG_INT_MAX;	min = TARG_INT_MIN;	break;
   2203 	case UINT:
   2204 		max = (u_int)TARG_UINT_MAX;min = 0;		break;
   2205 	case LONG:
   2206 		max = TARG_LONG_MAX;	min = TARG_LONG_MIN;	break;
   2207 	case ULONG:
   2208 		max = (u_long)TARG_ULONG_MAX; min = 0;		break;
   2209 	case QUAD:
   2210 		max = QUAD_MAX;		min = QUAD_MIN;		break;
   2211 	case UQUAD:
   2212 		max = (uint64_t)UQUAD_MAX; min = 0;		break;
   2213 	case FLOAT:
   2214 	case FCOMPLEX:
   2215 		max = FLT_MAX;		min = -FLT_MAX;		break;
   2216 	case DOUBLE:
   2217 	case DCOMPLEX:
   2218 		max = DBL_MAX;		min = -DBL_MAX;		break;
   2219 	case PTR:
   2220 		/* Got already an error because of float --> ptr */
   2221 	case LDOUBLE:
   2222 	case LCOMPLEX:
   2223 		max = LDBL_MAX;		min = -LDBL_MAX;	break;
   2224 	default:
   2225 		lint_assert(/*CONSTCOND*/false);
   2226 	}
   2227 	if (v->v_ldbl > max || v->v_ldbl < min) {
   2228 		lint_assert(nt != LDOUBLE);
   2229 		if (op == FARG) {
   2230 			/* conv. of '%s' to '%s' is out of range, ... */
   2231 			warning(295,
   2232 			    type_name(gettyp(ot)), type_name(tp), arg);
   2233 		} else {
   2234 			/* conversion of '%s' to '%s' is out of range */
   2235 			warning(119,
   2236 			    type_name(gettyp(ot)), type_name(tp));
   2237 		}
   2238 		v->v_ldbl = v->v_ldbl > 0 ? max : min;
   2239 	}
   2240 	if (nt == FLOAT) {
   2241 		nv->v_ldbl = (float)v->v_ldbl;
   2242 	} else if (nt == DOUBLE) {
   2243 		nv->v_ldbl = (double)v->v_ldbl;
   2244 	} else if (nt == LDOUBLE) {
   2245 		nv->v_ldbl = v->v_ldbl;
   2246 	} else {
   2247 		nv->v_quad = (nt == PTR || is_uinteger(nt)) ?
   2248 		    (int64_t)v->v_ldbl : (int64_t)v->v_ldbl;
   2249 	}
   2250 }
   2251 
   2252 static bool
   2253 convert_constant_to_floating(tspec_t nt, val_t *nv,
   2254 			     tspec_t ot, const val_t *v)
   2255 {
   2256 	if (nt == FLOAT) {
   2257 		nv->v_ldbl = (ot == PTR || is_uinteger(ot)) ?
   2258 		    (float)(uint64_t)v->v_quad : (float)v->v_quad;
   2259 	} else if (nt == DOUBLE) {
   2260 		nv->v_ldbl = (ot == PTR || is_uinteger(ot)) ?
   2261 		    (double)(uint64_t)v->v_quad : (double)v->v_quad;
   2262 	} else if (nt == LDOUBLE) {
   2263 		nv->v_ldbl = (ot == PTR || is_uinteger(ot)) ?
   2264 		    (ldbl_t)(uint64_t)v->v_quad : (ldbl_t)v->v_quad;
   2265 	} else
   2266 		return false;
   2267 	return true;
   2268 }
   2269 
   2270 /*
   2271  * Print a warning if bits which were set are lost due to the conversion.
   2272  * This can happen with operator ORASS only.
   2273  */
   2274 static void
   2275 convert_constant_check_range_bitor(size_t nsz, size_t osz, const val_t *v,
   2276 				   uint64_t xmask, op_t op)
   2277 {
   2278 	if (nsz < osz && (v->v_quad & xmask) != 0) {
   2279 		/* constant truncated by conv., op %s */
   2280 		warning(306, op_name(op));
   2281 	}
   2282 }
   2283 
   2284 /*
   2285  * Print a warning if additional bits are not all 1
   2286  * and the most significant bit of the old value is 1,
   2287  * or if at least one (but not all) removed bit was 0.
   2288  */
   2289 static void
   2290 convert_constant_check_range_bitand(size_t nsz, size_t osz,
   2291 				    uint64_t xmask, const val_t *nv,
   2292 				    tspec_t ot, const val_t *v,
   2293 				    const type_t *tp, op_t op)
   2294 {
   2295 	if (nsz > osz &&
   2296 	    (nv->v_quad & bit(osz - 1)) != 0 &&
   2297 	    (nv->v_quad & xmask) != xmask) {
   2298 		/* extra bits set to 0 in conversion of '%s' to '%s', ... */
   2299 		warning(309, type_name(gettyp(ot)),
   2300 		    type_name(tp), op_name(op));
   2301 	} else if (nsz < osz &&
   2302 		   (v->v_quad & xmask) != xmask &&
   2303 		   (v->v_quad & xmask) != 0) {
   2304 		/* constant truncated by conversion, op %s */
   2305 		warning(306, op_name(op));
   2306 	}
   2307 }
   2308 
   2309 static void
   2310 convert_constant_check_range_signed(op_t op, int arg)
   2311 {
   2312 	if (op == ASSIGN) {
   2313 		/* assignment of negative constant to unsigned type */
   2314 		warning(164);
   2315 	} else if (op == INIT) {
   2316 		/* initialization of unsigned with negative constant */
   2317 		warning(221);
   2318 	} else if (op == FARG) {
   2319 		/* conversion of negative constant to unsigned type, ... */
   2320 		warning(296, arg);
   2321 	} else if (modtab[op].m_comparison) {
   2322 		/* handled by check_integer_comparison() */
   2323 	} else {
   2324 		/* conversion of negative constant to unsigned type */
   2325 		warning(222);
   2326 	}
   2327 }
   2328 
   2329 /*
   2330  * Loss of significant bit(s). All truncated bits
   2331  * of unsigned types or all truncated bits plus the
   2332  * msb of the target for signed types are considered
   2333  * to be significant bits. Loss of significant bits
   2334  * means that at least one of the bits was set in an
   2335  * unsigned type or that at least one but not all of
   2336  * the bits was set in a signed type.
   2337  * Loss of significant bits means that it is not
   2338  * possible, also not with necessary casts, to convert
   2339  * back to the original type. A example for a
   2340  * necessary cast is:
   2341  *	char c;	int	i; c = 128;
   2342  *	i = c;			** yields -128 **
   2343  *	i = (unsigned char)c;	** yields 128 **
   2344  */
   2345 static void
   2346 convert_constant_check_range_truncated(op_t op, int arg, const type_t *tp,
   2347 				       tspec_t ot)
   2348 {
   2349 	if (op == ASSIGN && tp->t_bitfield) {
   2350 		/* precision lost in bit-field assignment */
   2351 		warning(166);
   2352 	} else if (op == ASSIGN) {
   2353 		/* constant truncated by assignment */
   2354 		warning(165);
   2355 	} else if (op == INIT && tp->t_bitfield) {
   2356 		/* bit-field initializer does not fit */
   2357 		warning(180);
   2358 	} else if (op == INIT) {
   2359 		/* initializer does not fit */
   2360 		warning(178);
   2361 	} else if (op == CASE) {
   2362 		/* case label affected by conversion */
   2363 		warning(196);
   2364 	} else if (op == FARG) {
   2365 		/* conversion of '%s' to '%s' is out of range, arg #%d */
   2366 		warning(295,
   2367 		    type_name(gettyp(ot)), type_name(tp), arg);
   2368 	} else {
   2369 		/* conversion of '%s' to '%s' is out of range */
   2370 		warning(119,
   2371 		    type_name(gettyp(ot)), type_name(tp));
   2372 	}
   2373 }
   2374 
   2375 static void
   2376 convert_constant_check_range_loss(op_t op, int arg, const type_t *tp,
   2377 				  tspec_t ot)
   2378 {
   2379 	if (op == ASSIGN && tp->t_bitfield) {
   2380 		/* precision lost in bit-field assignment */
   2381 		warning(166);
   2382 	} else if (op == INIT && tp->t_bitfield) {
   2383 		/* bit-field initializer out of range */
   2384 		warning(11);
   2385 	} else if (op == CASE) {
   2386 		/* case label affected by conversion */
   2387 		warning(196);
   2388 	} else if (op == FARG) {
   2389 		/* conversion of '%s' to '%s' is out of range, arg #%d */
   2390 		warning(295,
   2391 		    type_name(gettyp(ot)), type_name(tp), arg);
   2392 	} else {
   2393 		/* conversion of '%s' to '%s' is out of range */
   2394 		warning(119,
   2395 		    type_name(gettyp(ot)), type_name(tp));
   2396 	}
   2397 }
   2398 
   2399 static void
   2400 convert_constant_check_range(tspec_t ot, const type_t *tp, tspec_t nt,
   2401 			     op_t op, int arg, const val_t *v, val_t *nv)
   2402 {
   2403 	int	osz, nsz;
   2404 	int64_t	xmask, xmsk1;
   2405 
   2406 	osz = size_in_bits(ot);
   2407 	nsz = tp->t_bitfield ? tp->t_flen : size_in_bits(nt);
   2408 	xmask = value_bits(nsz) ^ value_bits(osz);
   2409 	xmsk1 = value_bits(nsz) ^ value_bits(osz - 1);
   2410 	/*
   2411 	 * For bitwise operations we are not interested in the
   2412 	 * value, but in the bits itself.
   2413 	 */
   2414 	if (op == ORASS || op == BITOR || op == BITXOR) {
   2415 		convert_constant_check_range_bitor(nsz, osz, v, xmask, op);
   2416 	} else if (op == ANDASS || op == BITAND) {
   2417 		convert_constant_check_range_bitand(nsz, osz, xmask, nv, ot,
   2418 		    v, tp, op);
   2419 	} else if ((nt != PTR && is_uinteger(nt)) &&
   2420 		   (ot != PTR && !is_uinteger(ot)) &&
   2421 		   v->v_quad < 0) {
   2422 		convert_constant_check_range_signed(op, arg);
   2423 	} else if (nv->v_quad != v->v_quad && nsz <= osz &&
   2424 		   (v->v_quad & xmask) != 0 &&
   2425 		   (is_uinteger(ot) || (v->v_quad & xmsk1) != xmsk1)) {
   2426 		convert_constant_check_range_truncated(op, arg, tp, ot);
   2427 	} else if (nv->v_quad != v->v_quad) {
   2428 		convert_constant_check_range_loss(op, arg, tp, ot);
   2429 	}
   2430 }
   2431 
   2432 /*
   2433  * Converts a typed constant to a constant of another type.
   2434  *
   2435  * op		operator which requires conversion
   2436  * arg		if op is FARG, # of argument
   2437  * tp		type in which to convert the constant
   2438  * nv		new constant
   2439  * v		old constant
   2440  */
   2441 void
   2442 convert_constant(op_t op, int arg, const type_t *tp, val_t *nv, val_t *v)
   2443 {
   2444 	tspec_t	ot, nt;
   2445 	int	sz;
   2446 	bool	range_check;
   2447 
   2448 	/*
   2449 	 * TODO: make 'v' const; the name of this function does not suggest
   2450 	 *  that it modifies 'v'.
   2451 	 */
   2452 	ot = v->v_tspec;
   2453 	nt = nv->v_tspec = tp->t_tspec;
   2454 	range_check = false;
   2455 
   2456 	if (nt == BOOL) {	/* C99 6.3.1.2 */
   2457 		nv->v_unsigned_since_c90 = false;
   2458 		nv->v_quad = is_nonzero_val(v) ? 1 : 0;
   2459 		return;
   2460 	}
   2461 
   2462 	if (ot == FLOAT || ot == DOUBLE || ot == LDOUBLE) {
   2463 		convert_constant_floating(op, arg, ot, tp, nt, v, nv);
   2464 	} else if (!convert_constant_to_floating(nt, nv, ot, v)) {
   2465 		range_check = true;	/* Check for lost precision. */
   2466 		nv->v_quad = v->v_quad;
   2467 	}
   2468 
   2469 	if ((v->v_unsigned_since_c90 && is_floating(nt)) ||
   2470 	    (v->v_unsigned_since_c90 && (is_integer(nt) && !is_uinteger(nt) &&
   2471 			    portable_size_in_bits(nt) >
   2472 			    portable_size_in_bits(ot)))) {
   2473 		/* ANSI C treats constant as unsigned */
   2474 		warning(157);
   2475 		v->v_unsigned_since_c90 = false;
   2476 	}
   2477 
   2478 	if (is_integer(nt)) {
   2479 		sz = tp->t_bitfield ? tp->t_flen : size_in_bits(nt);
   2480 		nv->v_quad = convert_integer(nv->v_quad, nt, sz);
   2481 	}
   2482 
   2483 	if (range_check && op != CVT)
   2484 		convert_constant_check_range(ot, tp, nt, op, arg, v, nv);
   2485 }
   2486 
   2487 /*
   2488  * Called if incompatible types were detected.
   2489  * Prints a appropriate warning.
   2490  */
   2491 static void
   2492 warn_incompatible_types(op_t op,
   2493 			const type_t *ltp, tspec_t lt,
   2494 			const type_t *rtp, tspec_t rt)
   2495 {
   2496 	const mod_t *mp;
   2497 
   2498 	mp = &modtab[op];
   2499 
   2500 	if (lt == VOID || (mp->m_binary && rt == VOID)) {
   2501 		/* void type illegal in expression */
   2502 		error(109);
   2503 	} else if (op == ASSIGN) {
   2504 		if ((lt == STRUCT || lt == UNION) &&
   2505 		    (rt == STRUCT || rt == UNION)) {
   2506 			/* assignment of different structures (%s != %s) */
   2507 			error(240, tspec_name(lt), tspec_name(rt));
   2508 		} else {
   2509 			/* cannot assign to '%s' from '%s' */
   2510 			error(171, type_name(ltp), type_name(rtp));
   2511 		}
   2512 	} else if (mp->m_binary) {
   2513 		/* operands of '%s' have incompatible types (%s != %s) */
   2514 		error(107, mp->m_name, tspec_name(lt), tspec_name(rt));
   2515 	} else {
   2516 		lint_assert(rt == NOTSPEC);
   2517 		/* operand of '%s' has invalid type (%s) */
   2518 		error(108, mp->m_name, tspec_name(lt));
   2519 	}
   2520 }
   2521 
   2522 /*
   2523  * Called if incompatible pointer types are detected.
   2524  * Print an appropriate warning.
   2525  */
   2526 static void
   2527 warn_incompatible_pointers(const mod_t *mp,
   2528 			   const type_t *ltp, const type_t *rtp)
   2529 {
   2530 	tspec_t	lt, rt;
   2531 
   2532 	lint_assert(ltp->t_tspec == PTR);
   2533 	lint_assert(rtp->t_tspec == PTR);
   2534 
   2535 	lt = ltp->t_subt->t_tspec;
   2536 	rt = rtp->t_subt->t_tspec;
   2537 
   2538 	if ((lt == STRUCT || lt == UNION) && (rt == STRUCT || rt == UNION)) {
   2539 		if (mp == NULL) {
   2540 			/* illegal structure pointer combination */
   2541 			warning(244);
   2542 		} else {
   2543 			/* incompatible structure pointers: '%s' '%s' '%s' */
   2544 			warning(245, type_name(ltp), mp->m_name, type_name(rtp));
   2545 		}
   2546 	} else {
   2547 		if (mp == NULL) {
   2548 			/* illegal combination of '%s' and '%s' */
   2549 			warning(184, type_name(ltp), type_name(rtp));
   2550 		} else {
   2551 			/* illegal combination of '%s' and '%s', op '%s' */
   2552 			warning(124,
   2553 			    type_name(ltp), type_name(rtp), mp->m_name);
   2554 		}
   2555 	}
   2556 }
   2557 
   2558 /* Return a type based on tp1, with added qualifiers from tp2. */
   2559 static type_t *
   2560 merge_qualifiers(type_t *tp1, const type_t *tp2)
   2561 {
   2562 	type_t *ntp, *nstp;
   2563 
   2564 	lint_assert(tp1->t_tspec == PTR);
   2565 	lint_assert(tp2->t_tspec == PTR);
   2566 
   2567 	bool c1 = tp1->t_subt->t_const;
   2568 	bool c2 = tp2->t_subt->t_const;
   2569 	bool v1 = tp1->t_subt->t_volatile;
   2570 	bool v2 = tp2->t_subt->t_volatile;
   2571 
   2572 	if (c1 == (c1 | c2) && v1 == (v1 | v2))
   2573 		return tp1;
   2574 
   2575 	nstp = expr_dup_type(tp1->t_subt);
   2576 	nstp->t_const |= c2;
   2577 	nstp->t_volatile |= v2;
   2578 
   2579 	ntp = expr_dup_type(tp1);
   2580 	ntp->t_subt = nstp;
   2581 	return ntp;
   2582 }
   2583 
   2584 /*
   2585  * Returns true if the given structure or union has a constant member
   2586  * (maybe recursively).
   2587  */
   2588 static bool
   2589 has_constant_member(const type_t *tp)
   2590 {
   2591 	sym_t *m;
   2592 
   2593 	lint_assert(is_struct_or_union(tp->t_tspec));
   2594 
   2595 	for (m = tp->t_str->sou_first_member; m != NULL; m = m->s_next) {
   2596 		const type_t *mtp = m->s_type;
   2597 		if (mtp->t_const)
   2598 			return true;
   2599 		if (is_struct_or_union(mtp->t_tspec) &&
   2600 		    has_constant_member(mtp))
   2601 			return true;
   2602 	}
   2603 	return false;
   2604 }
   2605 
   2606 /*
   2607  * Create a new node for one of the operators POINT and ARROW.
   2608  */
   2609 static tnode_t *
   2610 build_struct_access(op_t op, tnode_t *ln, tnode_t *rn)
   2611 {
   2612 	tnode_t	*ntn, *ctn;
   2613 	bool	nolval;
   2614 
   2615 	lint_assert(rn->tn_op == NAME);
   2616 	lint_assert(rn->tn_sym->s_value.v_tspec == INT);
   2617 	lint_assert(rn->tn_sym->s_scl == MOS || rn->tn_sym->s_scl == MOU);
   2618 
   2619 	/*
   2620 	 * Remember if the left operand is an lvalue (structure members
   2621 	 * are lvalues if and only if the structure itself is an lvalue).
   2622 	 */
   2623 	nolval = op == POINT && !ln->tn_lvalue;
   2624 
   2625 	if (op == POINT) {
   2626 		ln = build_address(ln, true);
   2627 	} else if (ln->tn_type->t_tspec != PTR) {
   2628 		lint_assert(tflag);
   2629 		lint_assert(is_integer(ln->tn_type->t_tspec));
   2630 		ln = convert(NOOP, 0, expr_derive_type(gettyp(VOID), PTR), ln);
   2631 	}
   2632 
   2633 	ctn = build_integer_constant(PTRDIFF_TSPEC,
   2634 	    rn->tn_sym->s_value.v_quad / CHAR_SIZE);
   2635 
   2636 	ntn = new_tnode(PLUS, expr_derive_type(rn->tn_type, PTR), ln, ctn);
   2637 	if (ln->tn_op == CON)
   2638 		ntn = fold(ntn);
   2639 
   2640 	if (rn->tn_type->t_bitfield) {
   2641 		ntn = new_tnode(FSEL, ntn->tn_type->t_subt, ntn, NULL);
   2642 	} else {
   2643 		ntn = new_tnode(INDIR, ntn->tn_type->t_subt, ntn, NULL);
   2644 	}
   2645 
   2646 	if (nolval)
   2647 		ntn->tn_lvalue = false;
   2648 
   2649 	return ntn;
   2650 }
   2651 
   2652 /*
   2653  * Create a node for INCAFT, INCBEF, DECAFT and DECBEF.
   2654  */
   2655 static tnode_t *
   2656 build_prepost_incdec(op_t op, tnode_t *ln)
   2657 {
   2658 	tnode_t	*cn, *ntn;
   2659 
   2660 	lint_assert(ln != NULL);
   2661 
   2662 	if (ln->tn_type->t_tspec == PTR) {
   2663 		cn = plength(ln->tn_type);
   2664 	} else {
   2665 		cn = build_integer_constant(INT, (int64_t)1);
   2666 	}
   2667 	ntn = new_tnode(op, ln->tn_type, ln, cn);
   2668 
   2669 	return ntn;
   2670 }
   2671 
   2672 /*
   2673  * Create a node for REAL, IMAG
   2674  */
   2675 static tnode_t *
   2676 build_real_imag(op_t op, tnode_t *ln)
   2677 {
   2678 	tnode_t	*cn, *ntn;
   2679 
   2680 	lint_assert(ln != NULL);
   2681 
   2682 	if (ln->tn_op == NAME) {
   2683 		/*
   2684 		 * This may be too much, but it avoids wrong warnings.
   2685 		 * See d_c99_complex_split.c.
   2686 		 */
   2687 		mark_as_used(ln->tn_sym, false, false);
   2688 		mark_as_set(ln->tn_sym);
   2689 	}
   2690 
   2691 	switch (ln->tn_type->t_tspec) {
   2692 	case LCOMPLEX:
   2693 		/* XXX: integer and LDOUBLE don't match. */
   2694 		cn = build_integer_constant(LDOUBLE, (int64_t)1);
   2695 		break;
   2696 	case DCOMPLEX:
   2697 		/* XXX: integer and DOUBLE don't match. */
   2698 		cn = build_integer_constant(DOUBLE, (int64_t)1);
   2699 		break;
   2700 	case FCOMPLEX:
   2701 		/* XXX: integer and FLOAT don't match. */
   2702 		cn = build_integer_constant(FLOAT, (int64_t)1);
   2703 		break;
   2704 	default:
   2705 		/* __%s__ is illegal for type %s */
   2706 		error(276, op == REAL ? "real" : "imag",
   2707 		    type_name(ln->tn_type));
   2708 		return NULL;
   2709 	}
   2710 	ntn = new_tnode(op, cn->tn_type, ln, cn);
   2711 	ntn->tn_lvalue = true;
   2712 
   2713 	return ntn;
   2714 }
   2715 
   2716 /*
   2717  * Create a tree node for the unary & operator
   2718  */
   2719 static tnode_t *
   2720 build_address(tnode_t *tn, bool noign)
   2721 {
   2722 	tspec_t	t;
   2723 
   2724 	if (!noign && ((t = tn->tn_type->t_tspec) == ARRAY || t == FUNC)) {
   2725 		if (tflag)
   2726 			/* '&' before array or function: ignored */
   2727 			warning(127);
   2728 		return tn;
   2729 	}
   2730 
   2731 	/* eliminate &* */
   2732 	if (tn->tn_op == INDIR &&
   2733 	    tn->tn_left->tn_type->t_tspec == PTR &&
   2734 	    tn->tn_left->tn_type->t_subt == tn->tn_type) {
   2735 		return tn->tn_left;
   2736 	}
   2737 
   2738 	return new_tnode(ADDR, expr_derive_type(tn->tn_type, PTR), tn, NULL);
   2739 }
   2740 
   2741 /*
   2742  * Create a node for operators PLUS and MINUS.
   2743  */
   2744 static tnode_t *
   2745 build_plus_minus(op_t op, tnode_t *ln, tnode_t *rn)
   2746 {
   2747 	tnode_t	*ntn, *ctn;
   2748 	type_t	*tp;
   2749 
   2750 	/* If pointer and integer, then pointer to the lhs. */
   2751 	if (rn->tn_type->t_tspec == PTR && is_integer(ln->tn_type->t_tspec)) {
   2752 		ntn = ln;
   2753 		ln = rn;
   2754 		rn = ntn;
   2755 	}
   2756 
   2757 	if (ln->tn_type->t_tspec == PTR && rn->tn_type->t_tspec != PTR) {
   2758 
   2759 		/* XXX: this assertion should be easy to trigger */
   2760 		lint_assert(is_integer(rn->tn_type->t_tspec));
   2761 
   2762 		check_ctype_macro_invocation(ln, rn);
   2763 
   2764 		ctn = plength(ln->tn_type);
   2765 		if (rn->tn_type->t_tspec != ctn->tn_type->t_tspec)
   2766 			rn = convert(NOOP, 0, ctn->tn_type, rn);
   2767 		rn = new_tnode(MULT, rn->tn_type, rn, ctn);
   2768 		if (rn->tn_left->tn_op == CON)
   2769 			rn = fold(rn);
   2770 		ntn = new_tnode(op, ln->tn_type, ln, rn);
   2771 
   2772 	} else if (rn->tn_type->t_tspec == PTR) {
   2773 
   2774 		lint_assert(ln->tn_type->t_tspec == PTR);
   2775 		lint_assert(op == MINUS);
   2776 		tp = gettyp(PTRDIFF_TSPEC);
   2777 		ntn = new_tnode(op, tp, ln, rn);
   2778 		if (ln->tn_op == CON && rn->tn_op == CON)
   2779 			ntn = fold(ntn);
   2780 		ctn = plength(ln->tn_type);
   2781 		balance(NOOP, &ntn, &ctn);
   2782 		ntn = new_tnode(DIV, tp, ntn, ctn);
   2783 
   2784 	} else {
   2785 
   2786 		ntn = new_tnode(op, ln->tn_type, ln, rn);
   2787 
   2788 	}
   2789 	return ntn;
   2790 }
   2791 
   2792 /*
   2793  * Create a node for operators SHL and SHR.
   2794  */
   2795 static tnode_t *
   2796 build_bit_shift(op_t op, tnode_t *ln, tnode_t *rn)
   2797 {
   2798 	tspec_t	t;
   2799 	tnode_t	*ntn;
   2800 
   2801 	if ((t = rn->tn_type->t_tspec) != INT && t != UINT)
   2802 		rn = convert(CVT, 0, gettyp(INT), rn);
   2803 	ntn = new_tnode(op, ln->tn_type, ln, rn);
   2804 	return ntn;
   2805 }
   2806 
   2807 /*
   2808  * Create a node for COLON.
   2809  */
   2810 static tnode_t *
   2811 build_colon(tnode_t *ln, tnode_t *rn)
   2812 {
   2813 	tspec_t	lt, rt, pdt;
   2814 	type_t	*tp;
   2815 	tnode_t	*ntn;
   2816 
   2817 	lt = ln->tn_type->t_tspec;
   2818 	rt = rn->tn_type->t_tspec;
   2819 	pdt = PTRDIFF_TSPEC;
   2820 
   2821 	/*
   2822 	 * Arithmetic types are balanced, all other type combinations
   2823 	 * still need to be handled.
   2824 	 */
   2825 	if (is_arithmetic(lt) && is_arithmetic(rt)) {
   2826 		tp = ln->tn_type;
   2827 	} else if (lt == BOOL && rt == BOOL) {
   2828 		tp = ln->tn_type;
   2829 	} else if (lt == VOID || rt == VOID) {
   2830 		tp = gettyp(VOID);
   2831 	} else if (lt == STRUCT || lt == UNION) {
   2832 		/* Both types must be identical. */
   2833 		lint_assert(rt == STRUCT || rt == UNION);
   2834 		lint_assert(ln->tn_type->t_str == rn->tn_type->t_str);
   2835 		if (is_incomplete(ln->tn_type)) {
   2836 			/* unknown operand size, op %s */
   2837 			error(138, op_name(COLON));
   2838 			return NULL;
   2839 		}
   2840 		tp = ln->tn_type;
   2841 	} else if (lt == PTR && is_integer(rt)) {
   2842 		if (rt != pdt) {
   2843 			rn = convert(NOOP, 0, gettyp(pdt), rn);
   2844 			rt = pdt;
   2845 		}
   2846 		tp = ln->tn_type;
   2847 	} else if (rt == PTR && is_integer(lt)) {
   2848 		if (lt != pdt) {
   2849 			ln = convert(NOOP, 0, gettyp(pdt), ln);
   2850 			lt = pdt;
   2851 		}
   2852 		tp = rn->tn_type;
   2853 	} else if (lt == PTR && ln->tn_type->t_subt->t_tspec == VOID) {
   2854 		tp = merge_qualifiers(rn->tn_type, ln->tn_type);
   2855 	} else if (rt == PTR && rn->tn_type->t_subt->t_tspec == VOID) {
   2856 		tp = merge_qualifiers(ln->tn_type, rn->tn_type);
   2857 	} else {
   2858 		/*
   2859 		 * XXX For now we simply take the left type. This is
   2860 		 * probably wrong, if one type contains a function prototype
   2861 		 * and the other one, at the same place, only an old style
   2862 		 * declaration.
   2863 		 */
   2864 		tp = merge_qualifiers(ln->tn_type, rn->tn_type);
   2865 	}
   2866 
   2867 	ntn = new_tnode(COLON, tp, ln, rn);
   2868 
   2869 	return ntn;
   2870 }
   2871 
   2872 /*
   2873  * Create a node for an assignment operator (both = and op= ).
   2874  */
   2875 static tnode_t *
   2876 build_assignment(op_t op, tnode_t *ln, tnode_t *rn)
   2877 {
   2878 	tspec_t	lt, rt;
   2879 	tnode_t	*ntn, *ctn;
   2880 
   2881 	lint_assert(ln != NULL);
   2882 	lint_assert(rn != NULL);
   2883 
   2884 	lt = ln->tn_type->t_tspec;
   2885 	rt = rn->tn_type->t_tspec;
   2886 
   2887 	if ((op == ADDASS || op == SUBASS) && lt == PTR) {
   2888 		lint_assert(is_integer(rt));
   2889 		ctn = plength(ln->tn_type);
   2890 		if (rn->tn_type->t_tspec != ctn->tn_type->t_tspec)
   2891 			rn = convert(NOOP, 0, ctn->tn_type, rn);
   2892 		rn = new_tnode(MULT, rn->tn_type, rn, ctn);
   2893 		if (rn->tn_left->tn_op == CON)
   2894 			rn = fold(rn);
   2895 	}
   2896 
   2897 	if ((op == ASSIGN || op == RETURN || op == INIT) &&
   2898 	    (lt == STRUCT || rt == STRUCT)) {
   2899 		lint_assert(lt == rt);
   2900 		lint_assert(ln->tn_type->t_str == rn->tn_type->t_str);
   2901 		if (is_incomplete(ln->tn_type)) {
   2902 			if (op == RETURN) {
   2903 				/* cannot return incomplete type */
   2904 				error(212);
   2905 			} else {
   2906 				/* unknown operand size, op %s */
   2907 				error(138, op_name(op));
   2908 			}
   2909 			return NULL;
   2910 		}
   2911 	}
   2912 
   2913 	if (op == SHLASS) {
   2914 		if (portable_size_in_bits(lt) < portable_size_in_bits(rt)) {
   2915 			if (hflag)
   2916 				/* semantics of '%s' change in ANSI C; ... */
   2917 				warning(118, "<<=");
   2918 		}
   2919 	} else if (op != SHRASS) {
   2920 		if (op == ASSIGN || lt != PTR) {
   2921 			if (lt != rt ||
   2922 			    (ln->tn_type->t_bitfield && rn->tn_op == CON)) {
   2923 				rn = convert(op, 0, ln->tn_type, rn);
   2924 				rt = lt;
   2925 			}
   2926 		}
   2927 	}
   2928 
   2929 	ntn = new_tnode(op, ln->tn_type, ln, rn);
   2930 
   2931 	return ntn;
   2932 }
   2933 
   2934 /*
   2935  * Get length of type tp->t_subt.
   2936  */
   2937 static tnode_t *
   2938 plength(type_t *tp)
   2939 {
   2940 	int	elem, elsz;
   2941 
   2942 	lint_assert(tp->t_tspec == PTR);
   2943 	tp = tp->t_subt;
   2944 
   2945 	elem = 1;
   2946 	elsz = 0;
   2947 
   2948 	while (tp->t_tspec == ARRAY) {
   2949 		elem *= tp->t_dim;
   2950 		tp = tp->t_subt;
   2951 	}
   2952 
   2953 	switch (tp->t_tspec) {
   2954 	case FUNC:
   2955 		/* pointer to function is not allowed here */
   2956 		error(110);
   2957 		break;
   2958 	case VOID:
   2959 		/* cannot do pointer arithmetic on operand of unknown size */
   2960 		gnuism(136);
   2961 		break;
   2962 	case STRUCT:
   2963 	case UNION:
   2964 		if ((elsz = tp->t_str->sou_size_in_bits) == 0)
   2965 			/* cannot do pointer arithmetic on operand of ... */
   2966 			error(136);
   2967 		break;
   2968 	case ENUM:
   2969 		if (is_incomplete(tp)) {
   2970 			/* cannot do pointer arithmetic on operand of ... */
   2971 			warning(136);
   2972 		}
   2973 		/* FALLTHROUGH */
   2974 	default:
   2975 		if ((elsz = size_in_bits(tp->t_tspec)) == 0) {
   2976 			/* cannot do pointer arithmetic on operand of ... */
   2977 			error(136);
   2978 		} else {
   2979 			lint_assert(elsz != -1);
   2980 		}
   2981 		break;
   2982 	}
   2983 
   2984 	if (elem == 0 && elsz != 0) {
   2985 		/* cannot do pointer arithmetic on operand of unknown size */
   2986 		error(136);
   2987 	}
   2988 
   2989 	if (elsz == 0)
   2990 		elsz = CHAR_SIZE;
   2991 
   2992 	return build_integer_constant(PTRDIFF_TSPEC,
   2993 	    (int64_t)(elem * elsz / CHAR_SIZE));
   2994 }
   2995 
   2996 /*
   2997  * XXX
   2998  * Note: There appear to be a number of bugs in detecting overflow in
   2999  * this function. An audit and a set of proper regression tests are needed.
   3000  *     --Perry Metzger, Nov. 16, 2001
   3001  */
   3002 /*
   3003  * Do only as much as necessary to compute constant expressions.
   3004  * Called only if the operator allows folding and all operands are constants.
   3005  */
   3006 static tnode_t *
   3007 fold(tnode_t *tn)
   3008 {
   3009 	val_t *v;
   3010 	tspec_t t;
   3011 	bool utyp, ovfl;
   3012 	int64_t sl, sr = 0, q = 0, mask;
   3013 	uint64_t ul, ur = 0;
   3014 	tnode_t *cn;
   3015 
   3016 	v = xcalloc(1, sizeof(*v));
   3017 	v->v_tspec = t = tn->tn_type->t_tspec;
   3018 
   3019 	utyp = t == PTR || is_uinteger(t);
   3020 	ul = sl = tn->tn_left->tn_val->v_quad;
   3021 	if (modtab[tn->tn_op].m_binary)
   3022 		ur = sr = tn->tn_right->tn_val->v_quad;
   3023 
   3024 	mask = value_bits(size_in_bits(t));
   3025 	ovfl = false;
   3026 
   3027 	switch (tn->tn_op) {
   3028 	case UPLUS:
   3029 		q = sl;
   3030 		break;
   3031 	case UMINUS:
   3032 		q = -sl;
   3033 		if (sl != 0 && msb(q, t, -1) == msb(sl, t, -1))
   3034 			ovfl = true;
   3035 		break;
   3036 	case COMPL:
   3037 		q = ~sl;
   3038 		break;
   3039 	case MULT:
   3040 		if (utyp) {
   3041 			q = ul * ur;
   3042 			if (q != (q & mask))
   3043 				ovfl = true;
   3044 			else if ((ul != 0) && ((q / ul) != ur))
   3045 				ovfl = true;
   3046 		} else {
   3047 			q = sl * sr;
   3048 			if (msb(q, t, -1) != (msb(sl, t, -1) ^ msb(sr, t, -1)))
   3049 				ovfl = true;
   3050 		}
   3051 		break;
   3052 	case DIV:
   3053 		if (sr == 0) {
   3054 			/* division by 0 */
   3055 			error(139);
   3056 			q = utyp ? UQUAD_MAX : QUAD_MAX;
   3057 		} else {
   3058 			q = utyp ? (int64_t)(ul / ur) : sl / sr;
   3059 		}
   3060 		break;
   3061 	case MOD:
   3062 		if (sr == 0) {
   3063 			/* modulus by 0 */
   3064 			error(140);
   3065 			q = 0;
   3066 		} else {
   3067 			q = utyp ? (int64_t)(ul % ur) : sl % sr;
   3068 		}
   3069 		break;
   3070 	case PLUS:
   3071 		q = utyp ? (int64_t)(ul + ur) : sl + sr;
   3072 		if (msb(sl, t, -1) && msb(sr, t, -1)) {
   3073 			if (!msb(q, t, -1))
   3074 				ovfl = true;
   3075 		} else if (!msb(sl, t, -1) && !msb(sr, t, -1)) {
   3076 			if (msb(q, t, -1) && !utyp)
   3077 				ovfl = true;
   3078 		}
   3079 		break;
   3080 	case MINUS:
   3081 		q = utyp ? (int64_t)(ul - ur) : sl - sr;
   3082 		if (msb(sl, t, -1) && !msb(sr, t, -1)) {
   3083 			if (!msb(q, t, -1))
   3084 				ovfl = true;
   3085 		} else if (!msb(sl, t, -1) && msb(sr, t, -1)) {
   3086 			if (msb(q, t, -1))
   3087 				ovfl = true;
   3088 		}
   3089 		break;
   3090 	case SHL:
   3091 		q = utyp ? (int64_t)(ul << sr) : sl << sr;
   3092 		break;
   3093 	case SHR:
   3094 		/*
   3095 		 * The sign must be explicitly extended because
   3096 		 * shifts of signed values are implementation dependent.
   3097 		 */
   3098 		q = ul >> sr;
   3099 		q = convert_integer(q, t, size_in_bits(t) - (int)sr);
   3100 		break;
   3101 	case LT:
   3102 		q = (utyp ? ul < ur : sl < sr) ? 1 : 0;
   3103 		break;
   3104 	case LE:
   3105 		q = (utyp ? ul <= ur : sl <= sr) ? 1 : 0;
   3106 		break;
   3107 	case GE:
   3108 		q = (utyp ? ul >= ur : sl >= sr) ? 1 : 0;
   3109 		break;
   3110 	case GT:
   3111 		q = (utyp ? ul > ur : sl > sr) ? 1 : 0;
   3112 		break;
   3113 	case EQ:
   3114 		q = (utyp ? ul == ur : sl == sr) ? 1 : 0;
   3115 		break;
   3116 	case NE:
   3117 		q = (utyp ? ul != ur : sl != sr) ? 1 : 0;
   3118 		break;
   3119 	case BITAND:
   3120 		q = utyp ? (int64_t)(ul & ur) : sl & sr;
   3121 		break;
   3122 	case BITXOR:
   3123 		q = utyp ? (int64_t)(ul ^ ur) : sl ^ sr;
   3124 		break;
   3125 	case BITOR:
   3126 		q = utyp ? (int64_t)(ul | ur) : sl | sr;
   3127 		break;
   3128 	default:
   3129 		lint_assert(/*CONSTCOND*/false);
   3130 	}
   3131 
   3132 	/* XXX does not work for quads. */
   3133 	if (ovfl ||
   3134 	    ((uint64_t)(q | mask) != ~(uint64_t)0 && (q & ~mask) != 0)) {
   3135 		if (hflag)
   3136 			/* integer overflow detected, op %s */
   3137 			warning(141, op_name(tn->tn_op));
   3138 	}
   3139 
   3140 	v->v_quad = convert_integer(q, t, -1);
   3141 
   3142 	cn = build_constant(tn->tn_type, v);
   3143 	if (tn->tn_left->tn_system_dependent)
   3144 		cn->tn_system_dependent = true;
   3145 	if (modtab[tn->tn_op].m_binary && tn->tn_right->tn_system_dependent)
   3146 		cn->tn_system_dependent = true;
   3147 
   3148 	return cn;
   3149 }
   3150 
   3151 /*
   3152  * Fold constant nodes, as much as is needed for comparing the value with 0
   3153  * (test context, for controlling expressions).
   3154  */
   3155 static tnode_t *
   3156 fold_test(tnode_t *tn)
   3157 {
   3158 	bool	l, r;
   3159 	val_t	*v;
   3160 
   3161 	v = xcalloc(1, sizeof(*v));
   3162 	v->v_tspec = tn->tn_type->t_tspec;
   3163 	lint_assert(v->v_tspec == INT || (Tflag && v->v_tspec == BOOL));
   3164 
   3165 	l = constant_is_nonzero(tn->tn_left);
   3166 	r = modtab[tn->tn_op].m_binary && constant_is_nonzero(tn->tn_right);
   3167 
   3168 	switch (tn->tn_op) {
   3169 	case NOT:
   3170 		if (hflag && !constcond_flag)
   3171 			/* constant argument to '!' */
   3172 			warning(239);
   3173 		v->v_quad = !l ? 1 : 0;
   3174 		break;
   3175 	case LOGAND:
   3176 		v->v_quad = l && r ? 1 : 0;
   3177 		break;
   3178 	case LOGOR:
   3179 		v->v_quad = l || r ? 1 : 0;
   3180 		break;
   3181 	default:
   3182 		lint_assert(/*CONSTCOND*/false);
   3183 	}
   3184 
   3185 	return build_constant(tn->tn_type, v);
   3186 }
   3187 
   3188 /*
   3189  * Fold constant nodes having operands with floating point type.
   3190  */
   3191 static tnode_t *
   3192 fold_float(tnode_t *tn)
   3193 {
   3194 	val_t	*v;
   3195 	tspec_t	t;
   3196 	ldbl_t	l, r = 0;
   3197 
   3198 	fpe = 0;
   3199 	v = xcalloc(1, sizeof(*v));
   3200 	v->v_tspec = t = tn->tn_type->t_tspec;
   3201 
   3202 	lint_assert(is_floating(t));
   3203 	lint_assert(t == tn->tn_left->tn_type->t_tspec);
   3204 	lint_assert(!modtab[tn->tn_op].m_binary ||
   3205 	    t == tn->tn_right->tn_type->t_tspec);
   3206 
   3207 	l = tn->tn_left->tn_val->v_ldbl;
   3208 	if (modtab[tn->tn_op].m_binary)
   3209 		r = tn->tn_right->tn_val->v_ldbl;
   3210 
   3211 	switch (tn->tn_op) {
   3212 	case UPLUS:
   3213 		v->v_ldbl = l;
   3214 		break;
   3215 	case UMINUS:
   3216 		v->v_ldbl = -l;
   3217 		break;
   3218 	case MULT:
   3219 		v->v_ldbl = l * r;
   3220 		break;
   3221 	case DIV:
   3222 		if (r == 0.0) {
   3223 			/* division by 0 */
   3224 			error(139);
   3225 			if (t == FLOAT) {
   3226 				v->v_ldbl = l < 0 ? -FLT_MAX : FLT_MAX;
   3227 			} else if (t == DOUBLE) {
   3228 				v->v_ldbl = l < 0 ? -DBL_MAX : DBL_MAX;
   3229 			} else {
   3230 				v->v_ldbl = l < 0 ? -LDBL_MAX : LDBL_MAX;
   3231 			}
   3232 		} else {
   3233 			v->v_ldbl = l / r;
   3234 		}
   3235 		break;
   3236 	case PLUS:
   3237 		v->v_ldbl = l + r;
   3238 		break;
   3239 	case MINUS:
   3240 		v->v_ldbl = l - r;
   3241 		break;
   3242 	case LT:
   3243 		v->v_quad = l < r ? 1 : 0;
   3244 		break;
   3245 	case LE:
   3246 		v->v_quad = l <= r ? 1 : 0;
   3247 		break;
   3248 	case GE:
   3249 		v->v_quad = l >= r ? 1 : 0;
   3250 		break;
   3251 	case GT:
   3252 		v->v_quad = l > r ? 1 : 0;
   3253 		break;
   3254 	case EQ:
   3255 		v->v_quad = l == r ? 1 : 0;
   3256 		break;
   3257 	case NE:
   3258 		v->v_quad = l != r ? 1 : 0;
   3259 		break;
   3260 	default:
   3261 		lint_assert(/*CONSTCOND*/false);
   3262 	}
   3263 
   3264 	lint_assert(fpe != 0 || isnan((double)v->v_ldbl) == 0);
   3265 	if (fpe != 0 || finite((double)v->v_ldbl) == 0 ||
   3266 	    (t == FLOAT &&
   3267 	     (v->v_ldbl > FLT_MAX || v->v_ldbl < -FLT_MAX)) ||
   3268 	    (t == DOUBLE &&
   3269 	     (v->v_ldbl > DBL_MAX || v->v_ldbl < -DBL_MAX))) {
   3270 		/* floating point overflow detected, op %s */
   3271 		warning(142, op_name(tn->tn_op));
   3272 		if (t == FLOAT) {
   3273 			v->v_ldbl = v->v_ldbl < 0 ? -FLT_MAX : FLT_MAX;
   3274 		} else if (t == DOUBLE) {
   3275 			v->v_ldbl = v->v_ldbl < 0 ? -DBL_MAX : DBL_MAX;
   3276 		} else {
   3277 			v->v_ldbl = v->v_ldbl < 0 ? -LDBL_MAX : LDBL_MAX;
   3278 		}
   3279 		fpe = 0;
   3280 	}
   3281 
   3282 	return build_constant(tn->tn_type, v);
   3283 }
   3284 
   3285 
   3286 /*
   3287  * Create a constant node for sizeof.
   3288  */
   3289 tnode_t *
   3290 build_sizeof(const type_t *tp)
   3291 {
   3292 	int64_t size_in_bytes = type_size_in_bits(tp) / CHAR_SIZE;
   3293 	tnode_t *tn = build_integer_constant(SIZEOF_TSPEC, size_in_bytes);
   3294 	tn->tn_system_dependent = true;
   3295 	return tn;
   3296 }
   3297 
   3298 /*
   3299  * Create a constant node for offsetof.
   3300  */
   3301 tnode_t *
   3302 build_offsetof(const type_t *tp, const sym_t *sym)
   3303 {
   3304 	tspec_t t = tp->t_tspec;
   3305 	if (t != STRUCT && t != UNION)
   3306 		/* unacceptable operand of '%s' */
   3307 		error(111, "offsetof");
   3308 
   3309 	// XXX: wrong size, no checking for sym fixme
   3310 	int64_t offset_in_bytes = type_size_in_bits(tp) / CHAR_SIZE;
   3311 	tnode_t *tn = build_integer_constant(SIZEOF_TSPEC, offset_in_bytes);
   3312 	tn->tn_system_dependent = true;
   3313 	return tn;
   3314 }
   3315 
   3316 int64_t
   3317 type_size_in_bits(const type_t *tp)
   3318 {
   3319 	int	elem, elsz;
   3320 	bool	flex;
   3321 
   3322 	elem = 1;
   3323 	flex = false;
   3324 	while (tp->t_tspec == ARRAY) {
   3325 		flex = true;	/* allow c99 flex arrays [] [0] */
   3326 		elem *= tp->t_dim;
   3327 		tp = tp->t_subt;
   3328 	}
   3329 	if (elem == 0) {
   3330 		if (!flex) {
   3331 			/* cannot take size/alignment of incomplete type */
   3332 			error(143);
   3333 			elem = 1;
   3334 		}
   3335 	}
   3336 	switch (tp->t_tspec) {
   3337 	case FUNC:
   3338 		/* cannot take size/alignment of function */
   3339 		error(144);
   3340 		elsz = 1;
   3341 		break;
   3342 	case STRUCT:
   3343 	case UNION:
   3344 		if (is_incomplete(tp)) {
   3345 			/* cannot take size/alignment of incomplete type */
   3346 			error(143);
   3347 			elsz = 1;
   3348 		} else {
   3349 			elsz = tp->t_str->sou_size_in_bits;
   3350 		}
   3351 		break;
   3352 	case ENUM:
   3353 		if (is_incomplete(tp)) {
   3354 			/* cannot take size/alignment of incomplete type */
   3355 			warning(143);
   3356 		}
   3357 		/* FALLTHROUGH */
   3358 	default:
   3359 		if (tp->t_bitfield) {
   3360 			/* cannot take size/alignment of bit-field */
   3361 			error(145);
   3362 		}
   3363 		if (tp->t_tspec == VOID) {
   3364 			/* cannot take size/alignment of void */
   3365 			error(146);
   3366 			elsz = 1;
   3367 		} else {
   3368 			elsz = size_in_bits(tp->t_tspec);
   3369 			lint_assert(elsz > 0);
   3370 		}
   3371 		break;
   3372 	}
   3373 
   3374 	return (int64_t)elem * elsz;
   3375 }
   3376 
   3377 tnode_t *
   3378 build_alignof(const type_t *tp)
   3379 {
   3380 	switch (tp->t_tspec) {
   3381 	case ARRAY:
   3382 		break;
   3383 
   3384 	case FUNC:
   3385 		/* cannot take size/alignment of function */
   3386 		error(144);
   3387 		return 0;
   3388 
   3389 	case STRUCT:
   3390 	case UNION:
   3391 		if (is_incomplete(tp)) {
   3392 			/* cannot take size/alignment of incomplete type */
   3393 			error(143);
   3394 			return 0;
   3395 		}
   3396 		break;
   3397 	case ENUM:
   3398 		break;
   3399 	default:
   3400 		if (tp->t_bitfield) {
   3401 			/* cannot take size/alignment of bit-field */
   3402 			error(145);
   3403 			return 0;
   3404 		}
   3405 		if (tp->t_tspec == VOID) {
   3406 			/* cannot take size/alignment of void */
   3407 			error(146);
   3408 			return 0;
   3409 		}
   3410 		break;
   3411 	}
   3412 
   3413 	return build_integer_constant(SIZEOF_TSPEC,
   3414 	    (int64_t)alignment_in_bits(tp) / CHAR_SIZE);
   3415 }
   3416 
   3417 /*
   3418  * Type casts.
   3419  */
   3420 tnode_t *
   3421 cast(tnode_t *tn, type_t *tp)
   3422 {
   3423 	tspec_t	nt, ot;
   3424 
   3425 	if (tn == NULL)
   3426 		return NULL;
   3427 
   3428 	/*
   3429 	 * XXX: checking for tp == NULL is only a quick fix for PR 22119.
   3430 	 *  The proper fix needs to be investigated properly.
   3431 	 *  See d_pr_22119.c for how to get here.
   3432 	 */
   3433 	if (tp == NULL)
   3434 		return NULL;
   3435 
   3436 	tn = cconv(tn);
   3437 
   3438 	nt = tp->t_tspec;
   3439 	ot = tn->tn_type->t_tspec;
   3440 
   3441 	if (nt == VOID) {
   3442 		/*
   3443 		 * XXX ANSI C requires scalar types or void (Plauger & Brodie).
   3444 		 * But this seems really questionable.
   3445 		 */
   3446 	} else if (nt == UNION) {
   3447 		sym_t *m;
   3448 		struct_or_union *str = tp->t_str;
   3449 		if (!gflag) {
   3450 			/* union cast is a GCC extension */
   3451 			error(328);
   3452 			return NULL;
   3453 		}
   3454 		for (m = str->sou_first_member; m != NULL; m = m->s_next) {
   3455 			if (eqtype(m->s_type, tn->tn_type,
   3456 			    false, false, NULL)) {
   3457 				tn = expr_zalloc_tnode();
   3458 				tn->tn_op = CVT;
   3459 				tn->tn_type = tp;
   3460 				tn->tn_cast = true;
   3461 				tn->tn_right = NULL;
   3462 				return tn;
   3463 			}
   3464 		}
   3465 		/* type '%s' is not a member of '%s' */
   3466 		error(329, type_name(tn->tn_type), type_name(tp));
   3467 		return NULL;
   3468 	} else if (nt == STRUCT || nt == ARRAY || nt == FUNC) {
   3469 		/* Casting to a struct is an undocumented GCC extension. */
   3470 		if (!(gflag && nt == STRUCT))
   3471 			goto invalid_cast;
   3472 	} else if (ot == STRUCT || ot == UNION) {
   3473 		goto invalid_cast;
   3474 	} else if (ot == VOID) {
   3475 		/* improper cast of void expression */
   3476 		error(148);
   3477 		return NULL;
   3478 	} else if (is_integer(nt) && is_scalar(ot)) {
   3479 		/* ok */
   3480 	} else if (is_floating(nt) && is_arithmetic(ot)) {
   3481 		/* ok */
   3482 	} else if (nt == PTR && is_integer(ot)) {
   3483 		/* ok */
   3484 	} else if (nt == PTR && ot == PTR) {
   3485 		if (!tp->t_subt->t_const && tn->tn_type->t_subt->t_const) {
   3486 			if (hflag)
   3487 				/* cast discards 'const' from type '%s' */
   3488 				warning(275, type_name(tn->tn_type));
   3489 		}
   3490 	} else
   3491 		goto invalid_cast;
   3492 
   3493 	tn = convert(CVT, 0, tp, tn);
   3494 	tn->tn_cast = true;
   3495 
   3496 	return tn;
   3497 
   3498 invalid_cast:
   3499 	/* invalid cast from '%s' to '%s' */
   3500 	error(147, type_name(tn->tn_type), type_name(tp));
   3501 	return NULL;
   3502 }
   3503 
   3504 /*
   3505  * Create the node for a function argument.
   3506  * All necessary conversions and type checks are done in
   3507  * build_function_call because build_function_argument has no
   3508  * information about expected argument types.
   3509  */
   3510 tnode_t *
   3511 build_function_argument(tnode_t *args, tnode_t *arg)
   3512 {
   3513 	tnode_t	*ntn;
   3514 
   3515 	/*
   3516 	 * If there was a serious error in the expression for the argument,
   3517 	 * create a dummy argument so the positions of the remaining arguments
   3518 	 * will not change.
   3519 	 */
   3520 	if (arg == NULL)
   3521 		arg = build_integer_constant(INT, 0);
   3522 
   3523 	ntn = new_tnode(PUSH, arg->tn_type, arg, args);
   3524 
   3525 	return ntn;
   3526 }
   3527 
   3528 /*
   3529  * Create the node for a function call. Also check types of
   3530  * function arguments and insert conversions, if necessary.
   3531  */
   3532 tnode_t *
   3533 build_function_call(tnode_t *func, tnode_t *args)
   3534 {
   3535 	tnode_t	*ntn;
   3536 	op_t	fcop;
   3537 
   3538 	if (func == NULL)
   3539 		return NULL;
   3540 
   3541 	if (func->tn_op == NAME && func->tn_type->t_tspec == FUNC) {
   3542 		fcop = CALL;
   3543 	} else {
   3544 		fcop = ICALL;
   3545 	}
   3546 
   3547 	check_ctype_function_call(func, args);
   3548 
   3549 	/*
   3550 	 * after cconv() func will always be a pointer to a function
   3551 	 * if it is a valid function designator.
   3552 	 */
   3553 	func = cconv(func);
   3554 
   3555 	if (func->tn_type->t_tspec != PTR ||
   3556 	    func->tn_type->t_subt->t_tspec != FUNC) {
   3557 		/* illegal function (type %s) */
   3558 		error(149, type_name(func->tn_type));
   3559 		return NULL;
   3560 	}
   3561 
   3562 	args = check_function_arguments(func->tn_type->t_subt, args);
   3563 
   3564 	ntn = new_tnode(fcop, func->tn_type->t_subt->t_subt, func, args);
   3565 
   3566 	return ntn;
   3567 }
   3568 
   3569 /*
   3570  * Check types of all function arguments and insert conversions,
   3571  * if necessary.
   3572  */
   3573 static tnode_t *
   3574 check_function_arguments(type_t *ftp, tnode_t *args)
   3575 {
   3576 	tnode_t	*arg;
   3577 	sym_t	*asym;
   3578 	tspec_t	at;
   3579 	int	narg, npar, n, i;
   3580 
   3581 	/* get # of args in the prototype */
   3582 	npar = 0;
   3583 	for (asym = ftp->t_args; asym != NULL; asym = asym->s_next)
   3584 		npar++;
   3585 
   3586 	/* get # of args in function call */
   3587 	narg = 0;
   3588 	for (arg = args; arg != NULL; arg = arg->tn_right)
   3589 		narg++;
   3590 
   3591 	asym = ftp->t_args;
   3592 	if (ftp->t_proto && npar != narg && !(ftp->t_vararg && npar < narg)) {
   3593 		/* argument mismatch: %d arg%s passed, %d expected */
   3594 		error(150, narg, narg > 1 ? "s" : "", npar);
   3595 		asym = NULL;
   3596 	}
   3597 
   3598 	for (n = 1; n <= narg; n++) {
   3599 
   3600 		/*
   3601 		 * The rightmost argument is at the top of the argument
   3602 		 * subtree.
   3603 		 */
   3604 		for (i = narg, arg = args; i > n; i--, arg = arg->tn_right)
   3605 			continue;
   3606 
   3607 		/* some things which are always not allowed */
   3608 		if ((at = arg->tn_left->tn_type->t_tspec) == VOID) {
   3609 			/* void expressions may not be arguments, arg #%d */
   3610 			error(151, n);
   3611 			return NULL;
   3612 		} else if ((at == STRUCT || at == UNION) &&
   3613 			   is_incomplete(arg->tn_left->tn_type)) {
   3614 			/* argument cannot have unknown size, arg #%d */
   3615 			error(152, n);
   3616 			return NULL;
   3617 		} else if (is_integer(at) &&
   3618 			   arg->tn_left->tn_type->t_is_enum &&
   3619 			   is_incomplete(arg->tn_left->tn_type)) {
   3620 			/* argument cannot have unknown size, arg #%d */
   3621 			warning(152, n);
   3622 		}
   3623 
   3624 		/* class conversions (arg in value context) */
   3625 		arg->tn_left = cconv(arg->tn_left);
   3626 
   3627 		if (asym != NULL) {
   3628 			arg->tn_left = check_prototype_argument(
   3629 			    n, asym->s_type, arg->tn_left);
   3630 		} else {
   3631 			arg->tn_left = promote(NOOP, true, arg->tn_left);
   3632 		}
   3633 		arg->tn_type = arg->tn_left->tn_type;
   3634 
   3635 		if (asym != NULL)
   3636 			asym = asym->s_next;
   3637 	}
   3638 
   3639 	return args;
   3640 }
   3641 
   3642 /*
   3643  * Compare the type of an argument with the corresponding type of a
   3644  * prototype parameter. If it is a valid combination, but both types
   3645  * are not the same, insert a conversion to convert the argument into
   3646  * the type of the parameter.
   3647  */
   3648 static tnode_t *
   3649 check_prototype_argument(
   3650 	int	n,		/* pos of arg */
   3651 	type_t	*tp,		/* expected type (from prototype) */
   3652 	tnode_t	*tn)		/* argument */
   3653 {
   3654 	tnode_t	*ln;
   3655 	bool	dowarn;
   3656 
   3657 	ln = xcalloc(1, sizeof(*ln));
   3658 	ln->tn_type = expr_unqualified_type(tp);
   3659 	ln->tn_lvalue = true;
   3660 	if (typeok(FARG, n, ln, tn)) {
   3661 		if (!eqtype(tp, tn->tn_type,
   3662 		    true, false, (dowarn = false, &dowarn)) || dowarn)
   3663 			tn = convert(FARG, n, tp, tn);
   3664 	}
   3665 	free(ln);
   3666 	return tn;
   3667 }
   3668 
   3669 /*
   3670  * Return the value of an integral constant expression.
   3671  * If the expression is not constant or its type is not an integer
   3672  * type, an error message is printed.
   3673  */
   3674 val_t *
   3675 constant(tnode_t *tn, bool required)
   3676 {
   3677 	val_t	*v;
   3678 
   3679 	if (tn != NULL)
   3680 		tn = cconv(tn);
   3681 	if (tn != NULL)
   3682 		tn = promote(NOOP, false, tn);
   3683 
   3684 	v = xcalloc(1, sizeof(*v));
   3685 
   3686 	if (tn == NULL) {
   3687 		lint_assert(nerr != 0);
   3688 		debug_step("constant node is null; returning 1 instead");
   3689 		v->v_tspec = INT;
   3690 		v->v_quad = 1;
   3691 		return v;
   3692 	}
   3693 
   3694 	v->v_tspec = tn->tn_type->t_tspec;
   3695 
   3696 	if (tn->tn_op == CON) {
   3697 		lint_assert(tn->tn_type->t_tspec == tn->tn_val->v_tspec);
   3698 		if (is_integer(tn->tn_val->v_tspec)) {
   3699 			v->v_unsigned_since_c90 =
   3700 			    tn->tn_val->v_unsigned_since_c90;
   3701 			v->v_quad = tn->tn_val->v_quad;
   3702 			return v;
   3703 		}
   3704 		v->v_quad = tn->tn_val->v_ldbl;
   3705 	} else {
   3706 		v->v_quad = 1;
   3707 	}
   3708 
   3709 	if (required)
   3710 		/* integral constant expression expected */
   3711 		error(55);
   3712 	else
   3713 		/* variable array dimension is a C99/GCC extension */
   3714 		c99ism(318);
   3715 
   3716 	if (!is_integer(v->v_tspec))
   3717 		v->v_tspec = INT;
   3718 
   3719 	return v;
   3720 }
   3721 
   3722 static bool
   3723 is_constcond_false(const tnode_t *tn, tspec_t t)
   3724 {
   3725 	return (t == BOOL || t == INT) &&
   3726 	       tn->tn_op == CON && tn->tn_val->v_quad == 0;
   3727 }
   3728 
   3729 /*
   3730  * Perform some tests on expressions which can't be done in build_binary()
   3731  * and functions called by build_binary(). These tests must be done here
   3732  * because we need some information about the context in which the operations
   3733  * are performed.
   3734  * After all tests are performed and dofreeblk is true, expr() frees the
   3735  * memory which is used for the expression.
   3736  */
   3737 void
   3738 expr(tnode_t *tn, bool vctx, bool tctx, bool dofreeblk, bool is_do_while)
   3739 {
   3740 
   3741 	if (tn == NULL) {	/* in case of errors */
   3742 		expr_free_all();
   3743 		return;
   3744 	}
   3745 
   3746 	/* expr() is also called in global initializations */
   3747 	if (dcs->d_ctx != EXTERN && !is_do_while)
   3748 		check_statement_reachable();
   3749 
   3750 	check_expr_misc(tn, vctx, tctx, !tctx, false, false, false);
   3751 	if (tn->tn_op == ASSIGN) {
   3752 		if (hflag && tctx)
   3753 			/* assignment in conditional context */
   3754 			warning(159);
   3755 	} else if (tn->tn_op == CON) {
   3756 		if (hflag && tctx && !constcond_flag &&
   3757 		    !tn->tn_system_dependent &&
   3758 		    !(is_do_while &&
   3759 		      is_constcond_false(tn, tn->tn_type->t_tspec)))
   3760 			/* constant in conditional context */
   3761 			warning(161);
   3762 	}
   3763 	if (!modtab[tn->tn_op].m_has_side_effect) {
   3764 		/*
   3765 		 * for left operands of COMMA this warning is already
   3766 		 * printed
   3767 		 */
   3768 		if (tn->tn_op != COMMA && !vctx && !tctx)
   3769 			check_null_effect(tn);
   3770 	}
   3771 	debug_node(tn);
   3772 
   3773 	/* free the tree memory */
   3774 	if (dofreeblk)
   3775 		expr_free_all();
   3776 }
   3777 
   3778 static bool
   3779 has_side_effect(const tnode_t *tn) // NOLINT(misc-no-recursion)
   3780 {
   3781 	op_t op = tn->tn_op;
   3782 
   3783 	if (modtab[op].m_has_side_effect)
   3784 		return true;
   3785 
   3786 	if (op == CVT && tn->tn_type->t_tspec == VOID)
   3787 		return has_side_effect(tn->tn_left);
   3788 
   3789 	/* XXX: Why not has_side_effect(tn->tn_left) as well? */
   3790 	if (op == LOGAND || op == LOGOR)
   3791 		return has_side_effect(tn->tn_right);
   3792 
   3793 	/* XXX: Why not has_side_effect(tn->tn_left) as well? */
   3794 	if (op == QUEST)
   3795 		return has_side_effect(tn->tn_right);
   3796 
   3797 	if (op == COLON || op == COMMA) {
   3798 		return has_side_effect(tn->tn_left) ||
   3799 		       has_side_effect(tn->tn_right);
   3800 	}
   3801 
   3802 	return false;
   3803 }
   3804 
   3805 static bool
   3806 is_void_cast(const tnode_t *tn)
   3807 {
   3808 
   3809 	return tn->tn_op == CVT && tn->tn_cast &&
   3810 	       tn->tn_type->t_tspec == VOID;
   3811 }
   3812 
   3813 static bool
   3814 is_local_symbol(const tnode_t *tn)
   3815 {
   3816 
   3817 	return tn->tn_op == LOAD &&
   3818 	       tn->tn_left->tn_op == NAME &&
   3819 	       tn->tn_left->tn_sym->s_scl == AUTO;
   3820 }
   3821 
   3822 static bool
   3823 is_int_constant_zero(const tnode_t *tn)
   3824 {
   3825 
   3826 	return tn->tn_op == CON &&
   3827 	       tn->tn_type->t_tspec == INT &&
   3828 	       tn->tn_val->v_quad == 0;
   3829 }
   3830 
   3831 static void
   3832 check_null_effect(const tnode_t *tn)
   3833 {
   3834 
   3835 	if (!hflag)
   3836 		return;
   3837 	if (has_side_effect(tn))
   3838 		return;
   3839 	if (is_void_cast(tn) && is_local_symbol(tn->tn_left))
   3840 		return;
   3841 	if (is_void_cast(tn) && is_int_constant_zero(tn->tn_left))
   3842 		return;
   3843 
   3844 	/* expression has null effect */
   3845 	warning(129);
   3846 }
   3847 
   3848 /* ARGSUSED */
   3849 void
   3850 check_expr_misc(const tnode_t *tn, bool vctx, bool tctx,
   3851 		bool eqwarn, bool fcall, bool rvdisc, bool szof)
   3852 {
   3853 	tnode_t	*ln, *rn;
   3854 	const mod_t *mp;
   3855 	op_t	op;
   3856 	scl_t	sc;
   3857 	dinfo_t	*di;
   3858 
   3859 	if (tn == NULL)
   3860 		return;
   3861 
   3862 	ln = tn->tn_left;
   3863 	rn = tn->tn_right;
   3864 	mp = &modtab[op = tn->tn_op];
   3865 
   3866 	switch (op) {
   3867 	case ADDR:
   3868 		/* XXX: Taking warn_about_unreachable into account here feels wrong. */
   3869 		if (ln->tn_op == NAME && (reached || !warn_about_unreachable)) {
   3870 			if (!szof)
   3871 				mark_as_set(ln->tn_sym);
   3872 			mark_as_used(ln->tn_sym, fcall, szof);
   3873 		}
   3874 		if (ln->tn_op == INDIR && ln->tn_left->tn_op == PLUS)
   3875 			/* check the range of array indices */
   3876 			check_array_index(ln->tn_left, true);
   3877 		break;
   3878 	case LOAD:
   3879 		if (ln->tn_op == INDIR && ln->tn_left->tn_op == PLUS)
   3880 			/* check the range of array indices */
   3881 			check_array_index(ln->tn_left, false);
   3882 		/* FALLTHROUGH */
   3883 	case PUSH:
   3884 	case INCBEF:
   3885 	case DECBEF:
   3886 	case INCAFT:
   3887 	case DECAFT:
   3888 	case ADDASS:
   3889 	case SUBASS:
   3890 	case MULASS:
   3891 	case DIVASS:
   3892 	case MODASS:
   3893 	case ANDASS:
   3894 	case ORASS:
   3895 	case XORASS:
   3896 	case SHLASS:
   3897 	case SHRASS:
   3898 	case REAL:
   3899 	case IMAG:
   3900 		/* XXX: Taking warn_about_unreachable into account here feels wrong. */
   3901 		if (ln->tn_op == NAME && (reached || !warn_about_unreachable)) {
   3902 			sc = ln->tn_sym->s_scl;
   3903 			/*
   3904 			 * Look if there was a asm statement in one of the
   3905 			 * compound statements we are in. If not, we don't
   3906 			 * print a warning.
   3907 			 */
   3908 			for (di = dcs; di != NULL; di = di->d_next) {
   3909 				if (di->d_asm)
   3910 					break;
   3911 			}
   3912 			if (sc != EXTERN && sc != STATIC &&
   3913 			    !ln->tn_sym->s_set && !szof && di == NULL) {
   3914 				/* %s may be used before set */
   3915 				warning(158, ln->tn_sym->s_name);
   3916 				mark_as_set(ln->tn_sym);
   3917 			}
   3918 			mark_as_used(ln->tn_sym, false, false);
   3919 		}
   3920 		break;
   3921 	case ASSIGN:
   3922 		/* XXX: Taking warn_about_unreachable into account here feels wrong. */
   3923 		if (ln->tn_op == NAME && !szof && (reached || !warn_about_unreachable)) {
   3924 			mark_as_set(ln->tn_sym);
   3925 			if (ln->tn_sym->s_scl == EXTERN)
   3926 				outusg(ln->tn_sym);
   3927 		}
   3928 		if (ln->tn_op == INDIR && ln->tn_left->tn_op == PLUS)
   3929 			/* check the range of array indices */
   3930 			check_array_index(ln->tn_left, false);
   3931 		break;
   3932 	case CALL:
   3933 		lint_assert(ln->tn_op == ADDR);
   3934 		lint_assert(ln->tn_left->tn_op == NAME);
   3935 		if (!szof)
   3936 			outcall(tn, vctx || tctx, rvdisc);
   3937 		break;
   3938 	case EQ:
   3939 		if (hflag && eqwarn)
   3940 			/* operator '==' found where '=' was expected */
   3941 			warning(160);
   3942 		break;
   3943 	case CON:
   3944 	case NAME:
   3945 	case STRING:
   3946 		return;
   3947 		/* LINTED206: (enumeration values not handled in switch) */
   3948 	case BITOR:
   3949 	case BITXOR:
   3950 	case NE:
   3951 	case GE:
   3952 	case GT:
   3953 	case LE:
   3954 	case LT:
   3955 	case SHR:
   3956 	case SHL:
   3957 	case MINUS:
   3958 	case PLUS:
   3959 	case MOD:
   3960 	case DIV:
   3961 	case MULT:
   3962 	case INDIR:
   3963 	case UMINUS:
   3964 	case UPLUS:
   3965 	case DEC:
   3966 	case INC:
   3967 	case COMPL:
   3968 	case NOT:
   3969 	case POINT:
   3970 	case ARROW:
   3971 	case NOOP:
   3972 	case BITAND:
   3973 	case FARG:
   3974 	case CASE:
   3975 	case INIT:
   3976 	case RETURN:
   3977 	case ICALL:
   3978 	case CVT:
   3979 	case COMMA:
   3980 	case FSEL:
   3981 	case COLON:
   3982 	case QUEST:
   3983 	case LOGOR:
   3984 	case LOGAND:
   3985 		break;
   3986 	}
   3987 
   3988 	bool cvctx = mp->m_left_value_context;
   3989 	bool ctctx = mp->m_left_test_context;
   3990 	bool eq = mp->m_warn_if_operand_eq &&
   3991 		  !ln->tn_parenthesized &&
   3992 		  rn != NULL && !rn->tn_parenthesized;
   3993 
   3994 	/*
   3995 	 * values of operands of ':' are not used if the type of at least
   3996 	 * one of the operands (for gcc compatibility) is void
   3997 	 * XXX test/value context of QUEST should probably be used as
   3998 	 * context for both operands of COLON
   3999 	 */
   4000 	if (op == COLON && tn->tn_type->t_tspec == VOID)
   4001 		cvctx = ctctx = false;
   4002 	bool discard = op == CVT && tn->tn_type->t_tspec == VOID;
   4003 	check_expr_misc(ln, cvctx, ctctx, eq, op == CALL, discard, szof);
   4004 
   4005 	switch (op) {
   4006 	case PUSH:
   4007 		if (rn != NULL)
   4008 			check_expr_misc(rn, false, false, eq, false, false,
   4009 			    szof);
   4010 		break;
   4011 	case LOGAND:
   4012 	case LOGOR:
   4013 		check_expr_misc(rn, false, true, eq, false, false, szof);
   4014 		break;
   4015 	case COLON:
   4016 		check_expr_misc(rn, cvctx, ctctx, eq, false, false, szof);
   4017 		break;
   4018 	case COMMA:
   4019 		check_expr_misc(rn, vctx, tctx, eq, false, false, szof);
   4020 		break;
   4021 	default:
   4022 		if (mp->m_binary)
   4023 			check_expr_misc(rn, true, false, eq, false, false,
   4024 			    szof);
   4025 		break;
   4026 	}
   4027 }
   4028 
   4029 /*
   4030  * Checks the range of array indices, if possible.
   4031  * amper is set if only the address of the element is used. This
   4032  * means that the index is allowed to refer to the first element
   4033  * after the array.
   4034  */
   4035 static void
   4036 check_array_index(tnode_t *tn, bool amper)
   4037 {
   4038 	int	dim;
   4039 	tnode_t	*ln, *rn;
   4040 	int	elsz;
   4041 	int64_t	con;
   4042 
   4043 	ln = tn->tn_left;
   4044 	rn = tn->tn_right;
   4045 
   4046 	/* We can only check constant indices. */
   4047 	if (rn->tn_op != CON)
   4048 		return;
   4049 
   4050 	/* Return if the left node does not stem from an array. */
   4051 	if (ln->tn_op != ADDR)
   4052 		return;
   4053 	if (ln->tn_left->tn_op != STRING && ln->tn_left->tn_op != NAME)
   4054 		return;
   4055 	if (ln->tn_left->tn_type->t_tspec != ARRAY)
   4056 		return;
   4057 
   4058 	/*
   4059 	 * For incomplete array types, we can print a warning only if
   4060 	 * the index is negative.
   4061 	 */
   4062 	if (is_incomplete(ln->tn_left->tn_type) && rn->tn_val->v_quad >= 0)
   4063 		return;
   4064 
   4065 	/* Get the size of one array element */
   4066 	if ((elsz = length(ln->tn_type->t_subt, NULL)) == 0)
   4067 		return;
   4068 	elsz /= CHAR_SIZE;
   4069 
   4070 	/* Change the unit of the index from bytes to element size. */
   4071 	if (is_uinteger(rn->tn_type->t_tspec)) {
   4072 		con = (uint64_t)rn->tn_val->v_quad / elsz;
   4073 	} else {
   4074 		con = rn->tn_val->v_quad / elsz;
   4075 	}
   4076 
   4077 	dim = ln->tn_left->tn_type->t_dim + (amper ? 1 : 0);
   4078 
   4079 	if (!is_uinteger(rn->tn_type->t_tspec) && con < 0) {
   4080 		/* array subscript cannot be negative: %ld */
   4081 		warning(167, (long)con);
   4082 	} else if (dim > 0 && (uint64_t)con >= (uint64_t)dim) {
   4083 		/* array subscript cannot be > %d: %ld */
   4084 		warning(168, dim - 1, (long)con);
   4085 	}
   4086 }
   4087 
   4088 /*
   4089  * Check for ordered comparisons of unsigned values with 0.
   4090  */
   4091 static void
   4092 check_integer_comparison(op_t op, tnode_t *ln, tnode_t *rn)
   4093 {
   4094 	tspec_t	lt, rt;
   4095 
   4096 	lt = ln->tn_type->t_tspec;
   4097 	rt = rn->tn_type->t_tspec;
   4098 
   4099 	if (ln->tn_op != CON && rn->tn_op != CON)
   4100 		return;
   4101 
   4102 	if (!is_integer(lt) || !is_integer(rt))
   4103 		return;
   4104 
   4105 	if ((hflag || pflag) && lt == CHAR && rn->tn_op == CON &&
   4106 	    (rn->tn_val->v_quad < 0 ||
   4107 	     rn->tn_val->v_quad > (int)~(~0U << (CHAR_SIZE - 1)))) {
   4108 		/* nonportable character comparison, op %s */
   4109 		warning(230, op_name(op));
   4110 		return;
   4111 	}
   4112 	if ((hflag || pflag) && rt == CHAR && ln->tn_op == CON &&
   4113 	    (ln->tn_val->v_quad < 0 ||
   4114 	     ln->tn_val->v_quad > (int)~(~0U << (CHAR_SIZE - 1)))) {
   4115 		/* nonportable character comparison, op %s */
   4116 		warning(230, op_name(op));
   4117 		return;
   4118 	}
   4119 	if (is_uinteger(lt) && !is_uinteger(rt) &&
   4120 	    rn->tn_op == CON && rn->tn_val->v_quad <= 0) {
   4121 		if (rn->tn_val->v_quad < 0) {
   4122 			/* comparison of %s with %s, op %s */
   4123 			warning(162, type_name(ln->tn_type),
   4124 			    "negative constant", op_name(op));
   4125 		} else if (op == LT || op == GE || (hflag && op == LE)) {
   4126 			/* comparison of %s with %s, op %s */
   4127 			warning(162, type_name(ln->tn_type), "0", op_name(op));
   4128 		}
   4129 		return;
   4130 	}
   4131 	if (is_uinteger(rt) && !is_uinteger(lt) &&
   4132 	    ln->tn_op == CON && ln->tn_val->v_quad <= 0) {
   4133 		if (ln->tn_val->v_quad < 0) {
   4134 			/* comparison of %s with %s, op %s */
   4135 			warning(162, "negative constant",
   4136 			    type_name(rn->tn_type), op_name(op));
   4137 		} else if (op == GT || op == LE || (hflag && op == GE)) {
   4138 			/* comparison of %s with %s, op %s */
   4139 			warning(162, "0", type_name(rn->tn_type), op_name(op));
   4140 		}
   4141 		return;
   4142 	}
   4143 }
   4144 
   4145 /*
   4146  * Return whether the expression can be used for static initialization.
   4147  *
   4148  * Constant initialization expressions must be constant or an address
   4149  * of a static object with an optional offset. In the first case,
   4150  * the result is returned in *offsp. In the second case, the static
   4151  * object is returned in *symp and the offset in *offsp.
   4152  *
   4153  * The expression can consist of PLUS, MINUS, ADDR, NAME, STRING and
   4154  * CON. Type conversions are allowed if they do not change binary
   4155  * representation (including width).
   4156  *
   4157  * C99 6.6 "Constant expressions"
   4158  * C99 6.7.8p4 restricts initializers for static storage duration
   4159  */
   4160 bool
   4161 constant_addr(const tnode_t *tn, const sym_t **symp, ptrdiff_t *offsp)
   4162 {
   4163 	const sym_t *sym;
   4164 	ptrdiff_t offs1, offs2;
   4165 	tspec_t	t, ot;
   4166 
   4167 	switch (tn->tn_op) {
   4168 	case MINUS:
   4169 		if (tn->tn_right->tn_op == CVT)
   4170 			return constant_addr(tn->tn_right, symp, offsp);
   4171 		else if (tn->tn_right->tn_op != CON)
   4172 			return false;
   4173 		/* FALLTHROUGH */
   4174 	case PLUS:
   4175 		offs1 = offs2 = 0;
   4176 		if (tn->tn_left->tn_op == CON) {
   4177 			offs1 = (ptrdiff_t)tn->tn_left->tn_val->v_quad;
   4178 			if (!constant_addr(tn->tn_right, &sym, &offs2))
   4179 				return false;
   4180 		} else if (tn->tn_right->tn_op == CON) {
   4181 			offs2 = (ptrdiff_t)tn->tn_right->tn_val->v_quad;
   4182 			if (tn->tn_op == MINUS)
   4183 				offs2 = -offs2;
   4184 			if (!constant_addr(tn->tn_left, &sym, &offs1))
   4185 				return false;
   4186 		} else {
   4187 			return false;
   4188 		}
   4189 		*symp = sym;
   4190 		*offsp = offs1 + offs2;
   4191 		return true;
   4192 	case ADDR:
   4193 		if (tn->tn_left->tn_op == NAME) {
   4194 			*symp = tn->tn_left->tn_sym;
   4195 			*offsp = 0;
   4196 			return true;
   4197 		} else {
   4198 			/*
   4199 			 * If this would be the front end of a compiler we
   4200 			 * would return a label instead of 0, at least if
   4201 			 * 'tn->tn_left->tn_op == STRING'.
   4202 			 */
   4203 			*symp = NULL;
   4204 			*offsp = 0;
   4205 			return true;
   4206 		}
   4207 	case CVT:
   4208 		t = tn->tn_type->t_tspec;
   4209 		ot = tn->tn_left->tn_type->t_tspec;
   4210 		if ((!is_integer(t) && t != PTR) ||
   4211 		    (!is_integer(ot) && ot != PTR)) {
   4212 			return false;
   4213 		}
   4214 #ifdef notdef
   4215 		/*
   4216 		 * consider:
   4217 		 *	struct foo {
   4218 		 *		unsigned char a;
   4219 		 *	} f = {
   4220 		 *		(u_char)(u_long)(&(((struct foo *)0)->a))
   4221 		 *	};
   4222 		 * since psize(u_long) != psize(u_char) this fails.
   4223 		 */
   4224 		else if (psize(t) != psize(ot))
   4225 			return -1;
   4226 #endif
   4227 		return constant_addr(tn->tn_left, symp, offsp);
   4228 	default:
   4229 		return false;
   4230 	}
   4231 }
   4232 
   4233 /*
   4234  * Concatenate two string constants.
   4235  */
   4236 strg_t *
   4237 cat_strings(strg_t *strg1, strg_t *strg2)
   4238 {
   4239 	size_t	len1, len2, len;
   4240 
   4241 	if (strg1->st_tspec != strg2->st_tspec) {
   4242 		/* cannot concatenate wide and regular string literals */
   4243 		error(292);
   4244 		return strg1;
   4245 	}
   4246 
   4247 	len1 = strg1->st_len;
   4248 	len2 = strg2->st_len + 1;	/* + NUL */
   4249 	len = len1 + len2;
   4250 
   4251 #define COPY(F) \
   4252     do { \
   4253 	strg1->F = xrealloc(strg1->F, len * sizeof(*strg1->F)); \
   4254 	(void)memcpy(strg1->F + len1, strg2->F, len2 * sizeof(*strg1->F)); \
   4255 	free(strg2->F); \
   4256     } while (false)
   4257 
   4258 	if (strg1->st_tspec == CHAR)
   4259 		COPY(st_cp);
   4260 	else
   4261 		COPY(st_wcp);
   4262 
   4263 	strg1->st_len = len - 1; /* - NUL */
   4264 	free(strg2);
   4265 
   4266 	return strg1;
   4267 }
   4268 
   4269 static bool
   4270 is_confusing_precedence(op_t op, op_t lop, bool lparen, op_t rop, bool rparen)
   4271 {
   4272 
   4273 	if (op == SHL || op == SHR) {
   4274 		if (!lparen && (lop == PLUS || lop == MINUS))
   4275 			return true;
   4276 		if (!rparen && (rop == PLUS || rop == MINUS))
   4277 			return true;
   4278 		return false;
   4279 	}
   4280 
   4281 	if (op == LOGOR) {
   4282 		if (!lparen && lop == LOGAND)
   4283 			return true;
   4284 		if (!rparen && rop == LOGAND)
   4285 			return true;
   4286 		return false;
   4287 	}
   4288 
   4289 	lint_assert(op == BITAND || op == BITXOR || op == BITOR);
   4290 	if (!lparen && lop != op) {
   4291 		if (lop == PLUS || lop == MINUS)
   4292 			return true;
   4293 		if (lop == BITAND || lop == BITXOR)
   4294 			return true;
   4295 	}
   4296 	if (!rparen && rop != op) {
   4297 		if (rop == PLUS || rop == MINUS)
   4298 			return true;
   4299 		if (rop == BITAND || rop == BITXOR)
   4300 			return true;
   4301 	}
   4302 	return false;
   4303 }
   4304 
   4305 /*
   4306  * Print a warning if the given node has operands which should be
   4307  * parenthesized.
   4308  *
   4309  * XXX Does not work if an operand is a constant expression. Constant
   4310  * expressions are already folded.
   4311  */
   4312 static void
   4313 check_precedence_confusion(tnode_t *tn)
   4314 {
   4315 	tnode_t *ln, *rn;
   4316 
   4317 	if (!hflag)
   4318 		return;
   4319 
   4320 	debug_node(tn);
   4321 
   4322 	lint_assert(modtab[tn->tn_op].m_binary);
   4323 	for (ln = tn->tn_left; ln->tn_op == CVT; ln = ln->tn_left)
   4324 		continue;
   4325 	for (rn = tn->tn_right; rn->tn_op == CVT; rn = rn->tn_left)
   4326 		continue;
   4327 
   4328 	if (is_confusing_precedence(tn->tn_op,
   4329 	    ln->tn_op, ln->tn_parenthesized,
   4330 	    rn->tn_op, rn->tn_parenthesized)) {
   4331 		/* precedence confusion possible: parenthesize! */
   4332 		warning(169);
   4333 	}
   4334 }
   4335