xref: /src/tests/usr.bin/xlint/lint1/msg_132.c

/*	$NetBSD: msg_132.c,v 1.18 2022/06/16 16:58:36 rillig Exp $	*/
# 3 "msg_132.c"

// Test for message: conversion from '%s' to '%s' may lose accuracy [132]

/*
 * NetBSD's default lint flags only include a single -a, which only flags
 * narrowing conversions from long.  To get warnings for all narrowing
 * conversions, -a needs to be given more than once.
 *
 * https://gnats.netbsd.org/14531
 */

/* lint1-extra-flags: -aa */

unsigned char u8;
unsigned short u16;
unsigned int u32;
unsigned long long u64;

signed char s8;
signed short s16;
signed int s32;
signed long long s64;

void
unsigned_to_unsigned(void)
{
	/* expect+1: warning: conversion from 'unsigned short' to 'unsigned char' may lose accuracy [132] */
	u8 = u16;
	/* expect+1: warning: conversion from 'unsigned int' to 'unsigned char' may lose accuracy [132] */
	u8 = u32;
	/* expect+1: warning: conversion from 'unsigned long long' to 'unsigned char' may lose accuracy [132] */
	u8 = u64;

	u16 = u8;
	/* expect+1: warning: conversion from 'unsigned int' to 'unsigned short' may lose accuracy [132] */
	u16 = u32;
	/* expect+1: warning: conversion from 'unsigned long long' to 'unsigned short' may lose accuracy [132] */
	u16 = u64;

	u32 = u8;
	u32 = u16;
	/* expect+1: warning: conversion from 'unsigned long long' to 'unsigned int' may lose accuracy [132] */
	u32 = u64;

	u64 = u8;
	u64 = u16;
	u64 = u32;
}

void
unsigned_to_signed(void)
{
	/* expect+1: warning: conversion from 'unsigned short' to 'signed char' may lose accuracy [132] */
	s8 = u16;
	/* expect+1: warning: conversion from 'unsigned int' to 'signed char' may lose accuracy [132] */
	s8 = u32;
	/* expect+1: warning: conversion from 'unsigned long long' to 'signed char' may lose accuracy [132] */
	s8 = u64;

	s16 = u8;
	/* expect+1: warning: conversion from 'unsigned int' to 'short' may lose accuracy [132] */
	s16 = u32;
	/* expect+1: warning: conversion from 'unsigned long long' to 'short' may lose accuracy [132] */
	s16 = u64;

	s32 = u8;
	s32 = u16;
	/* expect+1: warning: conversion from 'unsigned long long' to 'int' may lose accuracy [132] */
	s32 = u64;

	s64 = u8;
	s64 = u16;
	s64 = u32;
}

void
signed_to_unsigned(void)
{
	/* expect+1: warning: conversion from 'short' to 'unsigned char' may lose accuracy [132] */
	u8 = s16;
	/* expect+1: warning: conversion from 'int' to 'unsigned char' may lose accuracy [132] */
	u8 = s32;
	/* expect+1: warning: conversion from 'long long' to 'unsigned char' may lose accuracy [132] */
	u8 = s64;

	u16 = s8;
	/* expect+1: warning: conversion from 'int' to 'unsigned short' may lose accuracy [132] */
	u16 = s32;
	/* expect+1: warning: conversion from 'long long' to 'unsigned short' may lose accuracy [132] */
	u16 = s64;

	u32 = s8;
	u32 = s16;
	/* expect+1: warning: conversion from 'long long' to 'unsigned int' may lose accuracy [132] */
	u32 = s64;

	u64 = s8;
	u64 = s16;
	u64 = s32;
}

void
signed_to_signed(void)
{
	/* expect+1: warning: conversion from 'short' to 'signed char' may lose accuracy [132] */
	s8 = s16;
	/* expect+1: warning: conversion from 'int' to 'signed char' may lose accuracy [132] */
	s8 = s32;
	/* expect+1: warning: conversion from 'long long' to 'signed char' may lose accuracy [132] */
	s8 = s64;

	s16 = s8;
	/* expect+1: warning: conversion from 'int' to 'short' may lose accuracy [132] */
	s16 = s32;
	/* expect+1: warning: conversion from 'long long' to 'short' may lose accuracy [132] */
	s16 = s64;

	s32 = s8;
	s32 = s16;
	/* expect+1: warning: conversion from 'long long' to 'int' may lose accuracy [132] */
	s32 = s64;

	s64 = s8;
	s64 = s16;
	s64 = s32;
}

/*
 * Before tree.c 1.268 from 2021-04-06, lint wrongly warned that conversion
 * to _Bool might lose accuracy.  C99 6.3.1.2 defines a special conversion
 * rule from scalar to _Bool though by comparing the value to 0.
 */
_Bool
to_bool(long a, long b)
{
	/* seen in fp_lib.h, function wideRightShiftWithSticky */
	return a | b;
}

/* ARGSUSED */
const char *
cover_build_plus_minus(const char *arr, double idx)
{
	/* expect+3: error: operands of '+' have incompatible types (pointer != double) [107] */
	/* expect+2: warning: function 'cover_build_plus_minus' expects to return value [214] */
	if (idx > 0.0)
		return arr + idx;
	return arr + (unsigned int)idx;
}

int
non_constant_expression(void)
{
	/*
	 * Even though this variable definition looks like a constant, it
	 * does not fall within C's definition of an integer constant
	 * expression.  Due to that, lint does not perform constant folding
	 * on the expression built from this variable and thus doesn't know
	 * that the conversion will always succeed.
	 */
	const int not_a_constant = 8;
	/* expect+1: warning: conversion from 'unsigned long long' to 'int' may lose accuracy [132] */
	return not_a_constant * 8ULL;
}

typedef unsigned char u8_t;
typedef unsigned short u16_t;
typedef unsigned int u32_t;
typedef unsigned long long u64_t;

/*
 * PR 36668 notices that lint wrongly complains about the possible loss.
 *
 * The expression 'u8_t << 8' is guaranteed to fit into an 'u16_t', and its
 * lower 8 bits are guaranteed to be clear.  'u16_t | u8_t' is guaranteed to
 * fit into 'u16_t'.
 *
 * Since tree.c 1.444 from 2022-05-26, lint tracks simple bitwise and
 * arithmetic constraints across a single expression.
 */
static inline u16_t
be16dec(const void *buf)
{
	const u8_t *p = buf;

	/*
	 * Before tree.c 1.444 from 2022-05-26, lint complained that the
	 * conversion from 'int' to 'unsigned short' may lose accuracy.
	 */
	return ((u16_t)p[0]) << 8 | p[1];
}

/*
 * Since tree.c 1.434 from 2022-04-19, lint infers the possible values of
 * expressions of the form 'integer & constant', see can_represent.
 */
static inline void
be32enc(void *buf, u32_t u)
{
	u8_t *p = buf;

	p[0] = u >> 24 & 0xff;
	p[1] = u >> 16 & 0xff;
	p[2] = u >> 8 & 0xff;
	p[3] = u & 0xff;
}

u32_t
test_ic_shr(u64_t x)
{
	if (x > 3)
		return x >> 32;
	if (x > 2)
		/* expect+1: warning: conversion from 'unsigned long long' to 'unsigned int' may lose accuracy [132] */
		return x >> 31;
	/* expect+1: warning: conversion from 'unsigned long long' to 'unsigned int' may lose accuracy [132] */
	return x;
}


struct bit_fields {
	unsigned bits_32: 32;
	unsigned bits_5: 5;
	unsigned bits_3: 3;
};

unsigned char
test_bit_fields(struct bit_fields s, unsigned long long m)
{
	/* expect+1: warning: conversion from 'unsigned long long' to 'unsigned int' may lose accuracy [132] */
	s.bits_3 = s.bits_32 & m;

	s.bits_5 = s.bits_3 & m;
	s.bits_32 = s.bits_5 & m;

	/* expect+1: warning: conversion from 'unsigned long long' to 'unsigned char' may lose accuracy [132] */
	return s.bits_32 & m;
}