xref: /src/usr.bin/xlint/lint2/chk.c

/* $NetBSD: chk.c,v 1.72 2025/05/24 07:38:59 rillig Exp $ */

/*
 * Copyright (c) 1996 Christopher G. Demetriou.  All Rights Reserved.
 * Copyright (c) 1994, 1995 Jochen Pohl
 * All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Jochen Pohl for
 *	The NetBSD Project.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif

#include <sys/cdefs.h>
#if defined(__RCSID)
__RCSID("$NetBSD: chk.c,v 1.72 2025/05/24 07:38:59 rillig Exp $");
#endif

#include <ctype.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>

#include "lint2.h"

static void check_used_not_defined(const hte_t *);
static void check_defined_not_used(const hte_t *);
static void check_declared_not_used_or_defined(const hte_t *);
static void check_multiple_definitions(const hte_t *);
static void chkvtui(const hte_t *, const sym_t *, const sym_t *);
static void chkvtdi(const hte_t *, const sym_t *, const sym_t *);
static void chkfaui(const hte_t *, const sym_t *, const sym_t *);
static void chkau(const hte_t *, int, const sym_t *, const sym_t *,
    const pos_t *, const fcall_t *, const fcall_t *,
    const type_t *, const type_t *);
static void check_return_values(const hte_t *, const sym_t *);
static void check_argument_declarations(const hte_t *,
    const sym_t *, const sym_t *);
static void printflike(const hte_t *, const fcall_t *,
    int, const char *, const type_t **);
static void scanflike(const hte_t *, const fcall_t *,
    int, const char *, const type_t **);
static void bad_format_string(const hte_t *, const fcall_t *);
static void inconsistent_arguments(const hte_t *, const fcall_t *, int);
static void too_few_arguments(const hte_t *, const fcall_t *);
static void too_many_arguments(const hte_t *, const fcall_t *);
static bool types_compatible(const type_t *, const type_t *,
    bool, bool, bool, bool *);
static bool prototypes_compatible(const type_t *, const type_t *, bool *);
static bool matches_no_arg_function(const type_t *, bool *);


/*
 * If there is a symbol named "main", mark it as used.
 */
void
mark_main_as_used(void)
{
	hte_t *hte;

	if ((hte = htab_search("main", false)) != NULL)
		hte->h_used = true;
}

/*
 * Performs all tests for a single name
 */
void
check_name(const hte_t *hte)
{
	sym_t *sym, *def, *pdecl, *decl;

	if (!uflag) {
		check_used_not_defined(hte);
		check_defined_not_used(hte);
		if (xflag)
			check_declared_not_used_or_defined(hte);
	}
	check_multiple_definitions(hte);

	/* Get definition, prototype declaration and declaration */
	def = pdecl = decl = NULL;
	for (sym = hte->h_syms; sym != NULL; sym = sym->s_next) {
		if (def == NULL && (sym->s_def == DEF || sym->s_def == TDEF))
			def = sym;
		if (pdecl == NULL && sym->s_def == DECL &&
		    TP(sym->s_type)->t_tspec == FUNC &&
		    TP(sym->s_type)->t_proto) {
			pdecl = sym;
		}
		if (decl == NULL && sym->s_def == DECL)
			decl = sym;
	}

	/* A prototype is better than an old-style declaration. */
	if (pdecl != NULL)
		decl = pdecl;

	chkvtui(hte, def, decl);

	chkvtdi(hte, def, decl);

	chkfaui(hte, def, decl);

	check_return_values(hte, def);

	check_argument_declarations(hte, def, decl);
}

/*
 * Print a warning if the name has been used, but not defined.
 */
static void
check_used_not_defined(const hte_t *hte)
{
	fcall_t *fcall;
	usym_t *usym;

	if (!hte->h_used || hte->h_def)
		return;

	if ((fcall = hte->h_calls) != NULL) {
		/* %s is used in %s but never defined */
		msg(0, hte->h_name, mkpos(&fcall->f_pos));
	} else if ((usym = hte->h_usyms) != NULL) {
		/* %s is used in %s but never defined */
		msg(0, hte->h_name, mkpos(&usym->u_pos));
	}
}

/*
 * Print a warning if the name has been defined, but never used.
 */
static void
check_defined_not_used(const hte_t *hte)
{
	sym_t *sym;

	if (!hte->h_def || hte->h_used)
		return;

	for (sym = hte->h_syms; sym != NULL; sym = sym->s_next) {
		if (sym->s_def == DEF || sym->s_def == TDEF) {
			/* %s is defined in %s but never used */
			msg(1, hte->h_name, mkpos(&sym->s_pos));
			break;
		}
	}
}

/*
 * Print a warning if the variable has been declared, but is not used
 * or defined.
 */
static void
check_declared_not_used_or_defined(const hte_t *hte)
{
	sym_t *sym;

	if (hte->h_syms == NULL || hte->h_used || hte->h_def)
		return;

	sym = hte->h_syms;
	if (TP(sym->s_type)->t_tspec == FUNC)
		return;

	if (sym->s_def != DECL)
		errx(1, "internal error: check_declared_not_used_or_defined");
	/* %s is declared in %s but never used or defined */
	msg(2, hte->h_name, mkpos(&sym->s_pos));
}

/*
 * Print a warning if there is more than one definition for
 * this name.
 */
static void
check_multiple_definitions(const hte_t *hte)
{
	sym_t *sym, *def1;

	if (!hte->h_def)
		return;

	def1 = NULL;
	for (sym = hte->h_syms; sym != NULL; sym = sym->s_next) {
		/*
		 * C90 allows tentative definitions of the same name in only
		 * one compilation unit.
		 */
		if (sym->s_def != DEF && (!sflag || sym->s_def != TDEF))
			continue;
		if (sym->s_inline)
			continue;
		if (def1 == NULL) {
			def1 = sym;
			continue;
		}
		/* %s has multiple definitions in %s and %s */
		msg(3, hte->h_name, mkpos(&def1->s_pos), mkpos(&sym->s_pos));
	}
}

/*
 * Print a warning if the return value assumed for a function call
 * differs from the return value of the function definition or
 * function declaration.
 *
 * If no definition/declaration can be found, the assumed return values
 * are always int. So there is no need to compare with another function
 * call as it's done for function arguments.
 */
static void
chkvtui(const hte_t *hte, const sym_t *def, const sym_t *decl)
{
	fcall_t *call;
	type_t *tp1, *tp2;
	bool dowarn, eq;
	tspec_t t1;

	if (hte->h_calls == NULL)
		return;

	if (def == NULL)
		def = decl;
	if (def == NULL)
		return;

	t1 = (tp1 = TP(def->s_type)->t_subt)->t_tspec;
	for (call = hte->h_calls; call != NULL; call = call->f_next) {
		tp2 = TP(call->f_type)->t_subt;
		eq = types_compatible(tp1, tp2,
		    true, false, false, (dowarn = false, &dowarn));
		if (!call->f_rused) {
			/* no return value used */
			if ((t1 == STRUCT || t1 == UNION) && !eq) {
				/*
				 * If a function returns a struct or union, it
				 * must be declared to return a struct or
				 * union, even if the return value is ignored.
				 * This is necessary because the caller must
				 * allocate stack space for the return value.
				 * If it does not, the return value would
				 * overwrite other data.
				 *
				 * XXX: The following message may be confusing
				 * because it occurs also if the return value
				 * was declared inconsistently. But this
				 * behavior matches pcc-based lint, so it is
				 * accepted for now.
				 */
				/* %s's return type in %s must be decl... */
				msg(17, hte->h_name,
				    mkpos(&def->s_pos), mkpos(&call->f_pos));
			}
			continue;
		}
		if (!eq || (sflag && dowarn)) {
			/* %s has its return value used inconsistently ... */
			msg(4, hte->h_name,
			    mkpos(&def->s_pos), mkpos(&call->f_pos));
		}
	}
}

/*
 * Print a warning if a definition/declaration does not match another
 * definition/declaration of the same name. For functions, only the
 * types of return values are tested.
 */
static void
chkvtdi(const hte_t *hte, const sym_t *def, const sym_t *decl)
{
	if (def == NULL)
		def = decl;
	if (def == NULL)
		return;

	const type_t *tp1 = TP(def->s_type);
	for (sym_t *sym = hte->h_syms; sym != NULL; sym = sym->s_next) {
		if (sym == def)
			continue;
		const type_t *tp2 = TP(sym->s_type);
		bool dowarn = false;
		bool is_func = tp1->t_tspec == FUNC && tp2->t_tspec == FUNC;
		const type_t *xt1 = is_func ? tp1->t_subt : tp1;
		const type_t *xt2 = is_func ? tp2->t_subt : tp2;
		bool eq = types_compatible(xt1, xt2,
		    is_func, false, false, &dowarn);
		if (!eq || (sflag && dowarn)) {
			/* %s %s '%s' at %s, versus '%s' at %s */
			msg(5, hte->h_name,
			    is_func ? "returns" : "has type",
			    type_name(xt1), mkpos(&def->s_pos),
			    type_name(xt2), mkpos(&sym->s_pos));
		}
	}
}

static int
total_args(int n, const type_t **tpp)
{
	for (; *tpp != NULL; tpp++)
		n++;
	return n;
}

/*
 * Print a warning if a function is called with arguments which does
 * not match the function definition, declaration or another call
 * of the same function.
 */
static void
chkfaui(const hte_t *hte, const sym_t *def, const sym_t *decl)
{
	const type_t *tp1, *tp2, **ap1, **ap2;
	const pos_t *pos1p = NULL;
	fcall_t *calls, *call, *call1;
	int n, as;
	arginf_t *ai;

	if ((calls = hte->h_calls) == NULL)
		return;

	/*
	 * If we find a function definition, we use this for comparison,
	 * otherwise the first prototype we can find. If there is no definition
	 * or prototype declaration, the first function call is used.
	 */
	tp1 = NULL;
	call1 = NULL;
	if (def != NULL) {
		if ((tp1 = TP(def->s_type))->t_tspec != FUNC)
			return;
		pos1p = &def->s_pos;
	} else if (decl != NULL && TP(decl->s_type)->t_proto) {
		if ((tp1 = TP(decl->s_type))->t_tspec != FUNC)
			return;
		pos1p = &decl->s_pos;
	}
	if (tp1 == NULL) {
		call1 = calls;
		calls = calls->f_next;
		if ((tp1 = TP(call1->f_type))->t_tspec != FUNC)
			return;
		pos1p = &call1->f_pos;
	}

	n = 1;
	for (call = calls; call != NULL; call = call->f_next) {
		if ((tp2 = TP(call->f_type))->t_tspec != FUNC)
			continue;
		ap1 = tp1->t_args;
		ap2 = tp2->t_args;
		n = 0;
		while (*ap1 != NULL && *ap2 != NULL) {
			if (def != NULL && def->s_check_only_first_args &&
			    n >= def->s_check_num_args)
				break;
			n++;
			chkau(hte, n, def, decl, pos1p, call1, call,
			    *ap1, *ap2);
			ap1++;
			ap2++;
		}
		if (*ap1 == *ap2) {
			/* equal # of arguments */
		} else if (def != NULL && def->s_check_only_first_args &&
		    n >= def->s_check_num_args) {
			/*
			 * function definition with VARARGS; The # of arguments
			 * of the call must be at least as large as the
			 * parameter of VARARGS.
			 */
		} else if (*ap2 != NULL && tp1->t_proto && tp1->t_vararg) {
			/*
			 * prototype with ... and function call with at least
			 * the same # of arguments as declared in the
			 * prototype.
			 */
		} else {
			/* %s has %d parameters in %s, versus %d ... */
			msg(7, hte->h_name, total_args(n, ap1), mkpos(pos1p),
			    total_args(n, ap2), mkpos(&call->f_pos));
			continue;
		}

		/* perform SCANFLIKE/PRINTFLIKE tests */
		if (def == NULL || (!def->s_printflike && !def->s_scanflike))
			continue;
		as = def->s_printflike
		    ? def->s_printflike_arg
		    : def->s_scanflike_arg;
		for (ai = call->f_args; ai != NULL; ai = ai->a_next) {
			if (ai->a_num == as)
				break;
		}
		if (ai == NULL || !ai->a_fmt)
			continue;
		if (def->s_printflike) {
			printflike(hte, call, n, ai->a_fstrg, ap2);
		} else {
			scanflike(hte, call, n, ai->a_fstrg, ap2);
		}
	}
}

/*
 * Check a single argument in a function call.
 *
 *	hte	a pointer to the hash table entry of the function
 *	n	the number of the argument (1..)
 *	def	the function definition or NULL
 *	decl	prototype declaration, old-style declaration or NULL
 *	pos1p	position of definition, declaration of first call
 *	call1	first call, if both def and decl are old-style def/decl
 *	call	checked call
 *	arg1	currently checked argument of def/decl/call1
 *	arg2	currently checked argument of call
 */
static void
chkau(const hte_t *hte,
    int n, const sym_t *def, const sym_t *decl,
    const pos_t *pos1p, const fcall_t *call1, const fcall_t *call,
    const type_t *arg1, const type_t *arg2)
{
	bool promote, asgn, dowarn;
	tspec_t t1, t2;
	arginf_t *ai, *ai1;

	/*
	 * If a function definition is available (def != NULL), we compare the
	 * function call (call) with the definition. Otherwise, if a function
	 * definition is available and it is not an old-style definition (decl
	 * != NULL && TP(decl->s_type)->t_proto), we compare the call with this
	 * declaration. Otherwise we compare it with the first call we have
	 * found (call1).
	 */

	/* arg1 must be promoted if it stems from an old-style definition */
	promote = def != NULL && def->s_old_style_function;

	/*
	 * If we compare with a definition or declaration, we must perform the
	 * same checks for qualifiers in indirected types as in assignments.
	 */
	asgn = def != NULL || (decl != NULL && TP(decl->s_type)->t_proto);

	dowarn = false;
	if (types_compatible(arg1, arg2, true, promote, asgn, &dowarn) &&
	    (!sflag || !dowarn))
		return;

	/*-
	 * Other lint implementations print warnings as soon as the type of an
	 * argument does not match exactly the expected type. The result are
	 * lots of warnings which are really not necessary.
	 * We print a warning only if
	 *	(0) at least one type is not an integer type and types differ
	 *	(1) hflag is set and types differ
	 *	(2) types differ, except in signedness
	 *
	 * If the argument is an integer constant whose msb is not set,
	 * signedness is ignored (e.g. 0 matches both signed and unsigned int).
	 * This is with and without hflag.
	 *
	 * If the argument is an integer constant with value 0 and the expected
	 * argument is of type pointer and the width of the integer constant is
	 * the same as the width of the pointer, no warning is printed.
	 */
	t1 = arg1->t_tspec;
	t2 = arg2->t_tspec;
	if (is_integer(t1) && is_integer(t2) &&
	    !arg1->t_is_enum && !arg2->t_is_enum) {
		if (promote) {
			/*
			 * XXX Here is a problem: Although it is possible to
			 * pass an int where a char/short it expected, there
			 * may be loss in significant digits. We should first
			 * check for const arguments if they can be converted
			 * into the original parameter type.
			 */
			if (t1 == FLOAT) {
				t1 = DOUBLE;
			} else if (t1 == CHAR || t1 == SCHAR) {
				t1 = INT;
			} else if (t1 == UCHAR) {
				t1 = tflag ? UINT : INT;
			} else if (t1 == SHORT) {
				t1 = INT;
			} else if (t1 == USHORT) {
				t1 = INT_MAX < USHRT_MAX || tflag ? UINT : INT;
			}
		}

		if (signed_type(t1) == signed_type(t2)) {

			/*
			 * types differ only in signedness; get information
			 * about arguments
			 */

			/*
			 * treat a definition like a call with variable
			 * arguments
			 */
			ai1 = call1 != NULL ? call1->f_args : NULL;

			/*
			 * if two calls are compared, ai1 is set to the
			 * information for the n-th argument, if this was a
			 * constant, otherwise to NULL
			 */
			for ( ; ai1 != NULL; ai1 = ai1->a_next) {
				if (ai1->a_num == n)
					break;
			}
			/*
			 * ai is set to the information of the n-th arg of the
			 * (second) call, if this was a constant, otherwise to
			 * NULL
			 */
			for (ai = call->f_args; ai != NULL; ai = ai->a_next) {
				if (ai->a_num == n)
					break;
			}

			if (ai1 == NULL && ai == NULL) {
				/* no constant at all */
				if (!hflag)
					return;
			} else if (ai1 == NULL || ai == NULL) {
				/* one constant */
				if (ai == NULL)
					ai = ai1;
				if (ai->a_zero || ai->a_pcon)
					/* same value in signed and unsigned */
					return;
				/* value (not representation) differently */
			} else {
				/*
				 * two constants, one signed, one unsigned; if
				 * the msb of one of the constants is set, the
				 * argument is used inconsistently.
				 */
				if (!ai1->a_ncon && !ai->a_ncon)
					return;
			}
		}

	} else if (t1 == PTR && is_integer(t2)) {
		for (ai = call->f_args; ai != NULL; ai = ai->a_next) {
			if (ai->a_num == n)
				break;
		}
		/*
		 * Vendor implementations of lint (e.g. HP-UX, Digital UNIX)
		 * don't care about the size of the integer argument, only
		 * whether or not it is zero.  We do the same.
		 */
		if (ai != NULL && ai->a_zero)
			return;
	}

	/* %s has argument %d with type '%s' at %s, versus '%s' at %s */
	msg(6, hte->h_name, n, type_name(arg1), mkpos(pos1p),
	    type_name(arg2), mkpos(&call->f_pos));
}

/*
 * Compare the types in the NULL-terminated array ap with the format
 * string fmt.
 */
static void
printflike(const hte_t *hte, const fcall_t *call,
    int n, const char *fmt, const type_t **ap)
{
	const char *fp;
	char fc;
	bool fwidth, prec, left, sign, space, alt, zero;
	tspec_t sz, t1, t2 = NO_TSPEC;
	const type_t *tp;

	fp = fmt;
	fc = *fp++;

	for (;;) {
		if (fc == '\0') {
			if (*ap != NULL)
				too_many_arguments(hte, call);
			break;
		}
		if (fc != '%') {
			bad_format_string(hte, call);
			break;
		}
		fc = *fp++;
		fwidth = prec = left = sign = space = alt = zero = false;
		sz = NO_TSPEC;

		/* Flags */
		for (;;) {
			if (fc == '-') {
				if (left)
					break;
				left = true;
			} else if (fc == '+') {
				if (sign)
					break;
				sign = true;
			} else if (fc == ' ') {
				if (space)
					break;
				space = true;
			} else if (fc == '#') {
				if (alt)
					break;
				alt = true;
			} else if (fc == '0') {
				if (zero)
					break;
				zero = true;
			} else {
				break;
			}
			fc = *fp++;
		}

		/* field width */
		if (ch_isdigit(fc)) {
			fwidth = true;
			do { fc = *fp++; } while (ch_isdigit(fc));
		} else if (fc == '*') {
			fwidth = true;
			fc = *fp++;
			if ((tp = *ap++) == NULL) {
				too_few_arguments(hte, call);
				break;
			}
			n++;
			if ((t1 = tp->t_tspec) != INT && (hflag || t1 != UINT))
				inconsistent_arguments(hte, call, n);
		}

		/* precision */
		if (fc == '.') {
			fc = *fp++;
			prec = true;
			if (ch_isdigit(fc)) {
				do {
					fc = *fp++;
				} while (ch_isdigit(fc));
			} else if (fc == '*') {
				fc = *fp++;
				if ((tp = *ap++) == NULL) {
					too_few_arguments(hte, call);
					break;
				}
				n++;
				if (tp->t_tspec != INT)
					inconsistent_arguments(hte, call, n);
			} else {
				bad_format_string(hte, call);
				break;
			}
		}

		if (fc == 'h') {
			sz = SHORT;
		} else if (fc == 'l') {
			sz = LONG;
		} else if (fc == 'q') {
			sz = LLONG;
		} else if (fc == 'L') {
			sz = LDOUBLE;
		}
		if (sz != NO_TSPEC)
			fc = *fp++;

		if (fc == '%') {
			if (sz != NO_TSPEC || left || sign || space ||
			    alt || zero || prec || fwidth) {
				bad_format_string(hte, call);
			}
			fc = *fp++;
			continue;
		}

		if (fc == '\0') {
			bad_format_string(hte, call);
			break;
		}

		if ((tp = *ap++) == NULL) {
			too_few_arguments(hte, call);
			break;
		}
		n++;
		if ((t1 = tp->t_tspec) == PTR)
			t2 = tp->t_subt->t_tspec;

		if (fc == 'd' || fc == 'i') {
			if (alt || sz == LDOUBLE) {
				bad_format_string(hte, call);
				break;
			}
		int_conv:
			if (sz == LONG) {
				if (t1 != LONG && (hflag || t1 != ULONG))
					inconsistent_arguments(hte, call, n);
			} else if (sz == LLONG) {
				if (t1 != LLONG && (hflag || t1 != ULLONG))
					inconsistent_arguments(hte, call, n);
			} else {
				/*
				 * SHORT is always promoted to INT, USHORT to
				 * INT or UINT.
				 */
				if (t1 != INT && (hflag || t1 != UINT))
					inconsistent_arguments(hte, call, n);
			}
		} else if (fc == 'o' || fc == 'u' || fc == 'x' || fc == 'X') {
			if ((alt && fc == 'u') || sz == LDOUBLE)
				bad_format_string(hte, call);
		uint_conv:
			if (sz == LONG) {
				if (t1 != ULONG && (hflag || t1 != LONG))
					inconsistent_arguments(hte, call, n);
			} else if (sz == LLONG) {
				if (t1 != ULLONG && (hflag || t1 != LLONG))
					inconsistent_arguments(hte, call, n);
			} else if (sz == SHORT) {
				/* USHORT was promoted to INT or UINT */
				if (t1 != UINT && t1 != INT)
					inconsistent_arguments(hte, call, n);
			} else {
				if (t1 != UINT && (hflag || t1 != INT))
					inconsistent_arguments(hte, call, n);
			}
		} else if (fc == 'D' || fc == 'O' || fc == 'U') {
			if ((alt && fc != 'O') || sz != NO_TSPEC || !tflag)
				bad_format_string(hte, call);
			sz = LONG;
			if (fc == 'D') {
				goto int_conv;
			} else {
				goto uint_conv;
			}
		} else if (fc == 'f' || fc == 'e' || fc == 'E' ||
		    fc == 'g' || fc == 'G') {
			if (sz == NO_TSPEC)
				sz = DOUBLE;
			if (sz != DOUBLE && sz != LDOUBLE)
				bad_format_string(hte, call);
			if (t1 != sz)
				inconsistent_arguments(hte, call, n);
		} else if (fc == 'c') {
			if (sz != NO_TSPEC || alt || zero)
				bad_format_string(hte, call);
			if (t1 != INT)
				inconsistent_arguments(hte, call, n);
		} else if (fc == 's') {
			if (sz != NO_TSPEC || alt || zero)
				bad_format_string(hte, call);
			if (t1 != PTR ||
			    (t2 != CHAR && t2 != UCHAR && t2 != SCHAR)) {
				inconsistent_arguments(hte, call, n);
			}
		} else if (fc == 'p') {
			if (fwidth || prec || sz != NO_TSPEC || alt || zero)
				bad_format_string(hte, call);
			if (t1 != PTR || (hflag && t2 != VOID))
				inconsistent_arguments(hte, call, n);
		} else if (fc == 'n') {
			if (fwidth || prec || alt || zero || sz == LDOUBLE)
				bad_format_string(hte, call);
			if (t1 != PTR) {
				inconsistent_arguments(hte, call, n);
			} else if (sz == LONG) {
				if (t2 != LONG && t2 != ULONG)
					inconsistent_arguments(hte, call, n);
			} else if (sz == SHORT) {
				if (t2 != SHORT && t2 != USHORT)
					inconsistent_arguments(hte, call, n);
			} else {
				if (t2 != INT && t2 != UINT)
					inconsistent_arguments(hte, call, n);
			}
		} else {
			bad_format_string(hte, call);
			break;
		}

		fc = *fp++;
	}
}

/*
 * Compare the types in the NULL-terminated array ap with the format
 * string fmt.
 */
static void
scanflike(const hte_t *hte, const fcall_t *call,
    int n, const char *fmt, const type_t **ap)
{
	const char *fp;
	char fc;
	bool noasgn, fwidth;
	tspec_t sz, t1 = NO_TSPEC, t2 = NO_TSPEC;
	const type_t *tp = NULL;

	fp = fmt;
	fc = *fp++;

	for (;;) {
		if (fc == '\0') {
			if (*ap != NULL)
				too_many_arguments(hte, call);
			break;
		}
		if (fc != '%') {
			bad_format_string(hte, call);
			break;
		}
		fc = *fp++;

		noasgn = fwidth = false;
		sz = NO_TSPEC;

		if (fc == '*') {
			noasgn = true;
			fc = *fp++;
		}

		if (ch_isdigit(fc)) {
			fwidth = true;
			do { fc = *fp++; } while (ch_isdigit(fc));
		}

		if (fc == 'h') {
			sz = SHORT;
		} else if (fc == 'l') {
			sz = LONG;
		} else if (fc == 'q') {
			sz = LLONG;
		} else if (fc == 'L') {
			sz = LDOUBLE;
		}
		if (sz != NO_TSPEC)
			fc = *fp++;

		if (fc == '%') {
			if (sz != NO_TSPEC || noasgn || fwidth)
				bad_format_string(hte, call);
			fc = *fp++;
			continue;
		}

		if (!noasgn) {
			if ((tp = *ap++) == NULL) {
				too_few_arguments(hte, call);
				break;
			}
			n++;
			if ((t1 = tp->t_tspec) == PTR)
				t2 = tp->t_subt->t_tspec;
		}

		if (fc == 'd' || fc == 'i' || fc == 'n') {
			if (sz == LDOUBLE)
				bad_format_string(hte, call);
			if (sz != SHORT && sz != LONG && sz != LLONG)
				sz = INT;
		conv:
			if (!noasgn) {
				if (t1 != PTR) {
					inconsistent_arguments(hte, call, n);
				} else if (t2 != signed_type(sz)) {
					inconsistent_arguments(hte, call, n);
				} else if (hflag && t2 != sz) {
					inconsistent_arguments(hte, call, n);
				} else if (tp->t_subt->t_const) {
					inconsistent_arguments(hte, call, n);
				}
			}
		} else if (fc == 'o' || fc == 'u' || fc == 'x') {
			if (sz == LDOUBLE)
				bad_format_string(hte, call);
			if (sz == SHORT) {
				sz = USHORT;
			} else if (sz == LONG) {
				sz = ULONG;
			} else if (sz == LLONG) {
				sz = ULLONG;
			} else {
				sz = UINT;
			}
			goto conv;
		} else if (fc == 'D') {
			if (sz != NO_TSPEC || !tflag)
				bad_format_string(hte, call);
			sz = LONG;
			goto conv;
		} else if (fc == 'O') {
			if (sz != NO_TSPEC || !tflag)
				bad_format_string(hte, call);
			sz = ULONG;
			goto conv;
		} else if (fc == 'X') {
			/*
			 * XXX valid in C90, but in NetBSD's libc implemented
			 * as "lx". That's why it should be avoided.
			 */
			if (sz != NO_TSPEC || !tflag)
				bad_format_string(hte, call);
			sz = ULONG;
			goto conv;
		} else if (fc == 'E') {
			/*
			 * XXX valid in C90, but in NetBSD's libc implemented
			 * as "lf". That's why it should be avoided.
			 */
			if (sz != NO_TSPEC || !tflag)
				bad_format_string(hte, call);
			sz = DOUBLE;
			goto conv;
		} else if (fc == 'F') {
			/* XXX only for backward compatibility */
			if (sz != NO_TSPEC || !tflag)
				bad_format_string(hte, call);
			sz = DOUBLE;
			goto conv;
		} else if (fc == 'G') {
			/*
			 * XXX valid in C90, but in NetBSD's libc not
			 * implemented
			 */
			if (sz != NO_TSPEC && sz != LONG && sz != LDOUBLE)
				bad_format_string(hte, call);
			goto fconv;
		} else if (fc == 'e' || fc == 'f' || fc == 'g') {
		fconv:
			if (sz == NO_TSPEC) {
				sz = FLOAT;
			} else if (sz == LONG) {
				sz = DOUBLE;
			} else if (sz != LDOUBLE) {
				bad_format_string(hte, call);
				sz = FLOAT;
			}
			goto conv;
		} else if (fc == 's' || fc == '[' || fc == 'c') {
			if (sz != NO_TSPEC)
				bad_format_string(hte, call);
			if (fc == '[') {
				if ((fc = *fp++) == '-') {
					bad_format_string(hte, call);
					fc = *fp++;
				}
				if (fc != ']') {
					bad_format_string(hte, call);
					if (fc == '\0')
						break;
				}
			}
			if (!noasgn) {
				if (t1 != PTR) {
					inconsistent_arguments(hte, call, n);
				} else if (t2 != CHAR && t2 != UCHAR &&
				    t2 != SCHAR) {
					inconsistent_arguments(hte, call, n);
				}
			}
		} else if (fc == 'p') {
			if (sz != NO_TSPEC)
				bad_format_string(hte, call);
			if (!noasgn) {
				if (t1 != PTR || t2 != PTR) {
					inconsistent_arguments(hte, call, n);
				} else if (tp->t_subt->t_subt->t_tspec!=VOID) {
					if (hflag)
						inconsistent_arguments(hte, call, n);
				}
			}
		} else {
			bad_format_string(hte, call);
			break;
		}

		fc = *fp++;
	}
}

static void
bad_format_string(const hte_t *hte, const fcall_t *call)
{

	/* %s is called with a malformed format string in %s */
	msg(13, hte->h_name, mkpos(&call->f_pos));
}

static void
inconsistent_arguments(const hte_t *hte, const fcall_t *call, int n)
{

	/* %s is called in %s with argument %d being incompatible with ... */
	msg(14, hte->h_name, mkpos(&call->f_pos), n);
}

static void
too_few_arguments(const hte_t *hte, const fcall_t *call)
{

	/* %s is called in %s with too few arguments for format string */
	msg(15, hte->h_name, mkpos(&call->f_pos));
}

static void
too_many_arguments(const hte_t *hte, const fcall_t *call)
{

	/* %s is called in %s with too many arguments for format string */
	msg(16, hte->h_name, mkpos(&call->f_pos));
}

/*
 * List of functions where we usually don't care about their result.
 * NB: Must be sorted.
 */
static const char ignorelist[][8] = {
	"memcpy",
	"memmove",
	"memset",
	"printf",
	"strcat",
	"strcpy",
	"vprintf",
};

/*
 * Print warnings for return values which are used but not returned,
 * or return values which are always or sometimes ignored.
 */
static void
check_return_values(const hte_t *hte, const sym_t *def)
{
	fcall_t *call;
	bool used, ignored;

	if (def == NULL)
		/* don't know whether or not the functions returns a value */
		return;

	if (hte->h_calls == NULL)
		return;

	if (def->s_function_has_return_value) {
		/*
		 * XXX as soon as we are able to disable single warnings, the
		 * following dependencies from hflag should be removed. But for
		 * now I don't want to be bothered by these warnings which are
		 * almost always useless.
		 */
		if (!hflag)
			return;
		if (hflag && bsearch(hte->h_name, ignorelist,
		    sizeof(ignorelist) / sizeof(ignorelist[0]),
		    sizeof(ignorelist[0]),
		    (int (*)(const void *, const void *))strcmp) != NULL)
			return;

		/* function has return value */
		used = ignored = false;
		for (call = hte->h_calls; call != NULL; call = call->f_next) {
			used |= call->f_rused || call->f_rdisc;
			ignored |= !call->f_rused && !call->f_rdisc;
		}
		if (!used && ignored) {
			/* %s returns a value that is always ignored */
			msg(8, hte->h_name);
		} else if (used && ignored) {
			/* %s returns a value that is sometimes ignored */
			msg(9, hte->h_name);
		}
	} else {
		/* function has no return value */
		for (call = hte->h_calls; call != NULL; call = call->f_next) {
			if (call->f_rused)
				/* %s has its return value used in %s but doesn't return one */
				msg(10, hte->h_name, mkpos(&call->f_pos));
		}
	}
}

/*
 * Print warnings for inconsistent argument declarations.
 */
static void
check_argument_declarations(const hte_t *hte,
    const sym_t *def, const sym_t *decl)
{
	bool osdef, eq, dowarn;
	int n;
	const sym_t *sym1, *sym;
	const type_t **ap1, **ap2, *tp1, *tp2;

	osdef = false;
	if (def != NULL) {
		osdef = def->s_old_style_function;
		sym1 = def;
	} else if (decl != NULL && TP(decl->s_type)->t_proto) {
		sym1 = decl;
	} else {
		return;
	}
	if (TP(sym1->s_type)->t_tspec != FUNC)
		return;

	/*
	 * XXX Prototypes should also be compared with old-style function
	 * declarations.
	 */

	for (sym = hte->h_syms; sym != NULL; sym = sym->s_next) {
		if (sym == sym1 || !TP(sym->s_type)->t_proto)
			continue;
		ap1 = TP(sym1->s_type)->t_args;
		ap2 = TP(sym->s_type)->t_args;
		n = 0;
		while (*ap1 != NULL && *ap2 != NULL) {
			const type_t *xt1, *xt2;
			dowarn = false;
			eq = types_compatible(xt1 = *ap1, xt2 = *ap2,
			    true, osdef, false, &dowarn);
			if (!eq || dowarn) {
				/* %s has parameter %d declared as '%s' ... */
				msg(11, hte->h_name, n + 1,
				    type_name(xt1), mkpos(&sym1->s_pos),
				    type_name(xt2), mkpos(&sym->s_pos));
			}
			n++;
			ap1++;
			ap2++;
		}
		if (*ap1 == *ap2) {
			tp1 = TP(sym1->s_type);
			tp2 = TP(sym->s_type);
			if (tp1->t_vararg == tp2->t_vararg)
				continue;
			if (tp2->t_vararg && sym1->s_check_only_first_args &&
			    sym1->s_check_num_args == n && !sflag) {
				continue;
			}
		}
		/* %s has %d parameters in %s, versus %d in %s */
		msg(12, hte->h_name,
		    total_args(n, ap1), mkpos(&sym1->s_pos),
		    total_args(n, ap2), mkpos(&sym->s_pos));
	}
}


/*
 * Check compatibility of two types. Returns whether types are compatible.
 *
 * ignqual	if set, ignore qualifiers of outermost type; used for
 *		function arguments
 * promote	if set, promote left type before comparison; used for
 *		comparisons of arguments with parameters of old-style
 *		definitions
 * asgn		left indirected type must have at least the same qualifiers
 *		like right indirected type (for assignments and function
 *		arguments)
 * *dowarn	set to true if an old-style declaration was compared with
 *		an incompatible prototype declaration
 */
static bool
types_compatible(const type_t *tp1, const type_t *tp2,
		 bool ignqual, bool promot, bool asgn, bool *dowarn)
{
	tspec_t t, to;
	int indir;

	to = NO_TSPEC;
	indir = 0;

	while (tp1 != NULL && tp2 != NULL) {

		t = tp1->t_tspec;
		if (promot) {
			if (t == FLOAT) {
				t = DOUBLE;
			} else if (t == CHAR || t == SCHAR) {
				t = INT;
			} else if (t == UCHAR) {
				t = tflag ? UINT : INT;
			} else if (t == SHORT) {
				t = INT;
			} else if (t == USHORT) {
				t = INT_MAX < USHRT_MAX || tflag ? UINT : INT;
			}
		}

		if (asgn && to == PTR) {
			if (indir == 1 && (t == VOID || tp2->t_tspec == VOID))
				return true;
		}

		if (t != tp2->t_tspec) {
			/*
			 * Give pointer to types which differ only in
			 * signedness a chance if not sflag and not hflag.
			 */
			if (sflag || hflag || to != PTR)
				return false;
			if (signed_type(t) != signed_type(tp2->t_tspec))
				return false;
		}

		if (tp1->t_is_enum && tp2->t_is_enum) {
			if (tp1->t_istag && tp2->t_istag) {
				return tp1->t_tag == tp2->t_tag;
			} else if (tp1->t_istynam && tp2->t_istynam) {
				return tp1->t_tynam == tp2->t_tynam;
			} else if (tp1->t_isuniqpos && tp2->t_isuniqpos) {
				return (tp1->t_uniqpos.p_line ==
				      tp2->t_uniqpos.p_line &&
				    tp1->t_uniqpos.p_file ==
				      tp2->t_uniqpos.p_file &&
				    tp1->t_uniqpos.p_uniq ==
				      tp2->t_uniqpos.p_uniq);
			} else {
				return false;
			}
		}

		/*
		 * XXX Handle combinations of enum and int if eflag is set. But
		 * note: enum and 0 should be allowed.
		 */

		if (asgn && indir == 1) {
			if (!tp1->t_const && tp2->t_const)
				return false;
			if (!tp1->t_volatile && tp2->t_volatile)
				return false;
		} else if (!ignqual && !tflag) {
			if (tp1->t_const != tp2->t_const)
				return false;
			if (tp1->t_const != tp2->t_const)
				return false;
		}

		if (t == STRUCT || t == UNION) {
			if (tp1->t_istag && tp2->t_istag) {
				return tp1->t_tag == tp2->t_tag;
			} else if (tp1->t_istynam && tp2->t_istynam) {
				return tp1->t_tynam == tp2->t_tynam;
			} else if (tp1->t_isuniqpos && tp2->t_isuniqpos) {
				return (tp1->t_uniqpos.p_line ==
				      tp2->t_uniqpos.p_line &&
				    tp1->t_uniqpos.p_file ==
				      tp2->t_uniqpos.p_file &&
				    tp1->t_uniqpos.p_uniq ==
				      tp2->t_uniqpos.p_uniq);
			} else {
				return false;
			}
		}

		if (t == ARRAY && tp1->t_dim != tp2->t_dim) {
			if (tp1->t_dim != 0 && tp2->t_dim != 0)
				return false;
		}

		if (t == FUNC) {
			if (tp1->t_proto && tp2->t_proto) {
				if (!prototypes_compatible(tp1, tp2, dowarn))
					return false;
			} else if (tp1->t_proto) {
				if (!matches_no_arg_function(tp1, dowarn))
					return false;
			} else if (tp2->t_proto) {
				if (!matches_no_arg_function(tp2, dowarn))
					return false;
			}
		}

		tp1 = tp1->t_subt;
		tp2 = tp2->t_subt;
		ignqual = promot = false;
		to = t;
		indir++;
	}

	return tp1 == tp2;
}

/*
 * Compares arguments of two prototypes
 */
static bool
prototypes_compatible(const type_t *tp1, const type_t *tp2, bool *dowarn)
{

	if (tp1->t_vararg != tp2->t_vararg)
		return false;

	const type_t **a1 = tp1->t_args;
	const type_t **a2 = tp2->t_args;

	for (; *a1 != NULL && *a2 != NULL; a1++, a2++)
		if (!types_compatible(*a1, *a2, true, false, false, dowarn))
			return false;
	return *a1 == *a2;
}

/*
 * Returns whether all parameters of a prototype are compatible with an
 * old-style function declaration.
 *
 * This is the case if the following conditions are met:
 *	1. the prototype must have a fixed number of parameters
 *	2. no parameter is of type float
 *	3. no parameter is converted to another type if integer promotion
 *	   is applied on it
 */
static bool
matches_no_arg_function(const type_t *tp, bool *dowarn)
{
	if (tp->t_vararg && dowarn != NULL)
		*dowarn = true;
	for (const type_t **arg = tp->t_args; *arg != NULL; arg++) {
		tspec_t t = (*arg)->t_tspec;
		if (t == FLOAT)
			return false;
		if (t == CHAR || t == SCHAR || t == UCHAR)
			return false;
		if (t == SHORT || t == USHORT)
			return false;
	}
	return true;
}