1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include <assert.h>
10#include <cmath>
11#include <cstdint>
12#include <limits>
13#include <type_traits>
14
15#include "test_macros.h"
16
17template<class T>
18struct correct_size_int
19{
20 typedef typename std::conditional<sizeof(T) < sizeof(int), int, T>::type type;
21};
22
23template <class Source, class Result>
24void test_abs()
25{
26 Source neg_val = -5;
27 Source pos_val = 5;
28 Result res = 5;
29
30 ASSERT_SAME_TYPE(decltype(std::abs(neg_val)), Result);
31
32 assert(std::abs(neg_val) == res);
33 assert(std::abs(pos_val) == res);
34}
35
36void test_big()
37{
38 long long int big_value = std::numeric_limits<long long int>::max(); // a value too big for ints to store
39 long long int negative_big_value = -big_value;
40 assert(std::abs(negative_big_value) == big_value); // make sure it doesn't get casted to a smaller type
41}
42
43// The following is helpful to keep in mind:
44// 1byte == char <= short <= int <= long <= long long
45
46int main(int, char**)
47{
48 // On some systems char is unsigned.
49 // If that is the case, we should just test signed char twice.
50 typedef std::conditional<
51 std::is_signed<char>::value, char, signed char
52 >::type SignedChar;
53
54 // All types less than or equal to and not greater than int are promoted to int.
55 test_abs<short int, int>();
56 test_abs<SignedChar, int>();
57 test_abs<signed char, int>();
58
59 // These three calls have specific overloads:
60 test_abs<int, int>();
61 test_abs<long int, long int>();
62 test_abs<long long int, long long int>();
63
64 // Here there is no guarantee that int is larger than int8_t so we
65 // use a helper type trait to conditional test against int.
66 test_abs<std::int8_t, correct_size_int<std::int8_t>::type>();
67 test_abs<std::int16_t, correct_size_int<std::int16_t>::type>();
68 test_abs<std::int32_t, correct_size_int<std::int32_t>::type>();
69 test_abs<std::int64_t, correct_size_int<std::int64_t>::type>();
70
71 test_abs<long double, long double>();
72 test_abs<double, double>();
73 test_abs<float, float>();
74
75 test_big();
76
77 return 0;
78}
79

source code of libcxx/test/std/numerics/c.math/abs.pass.cpp