libcxx/test/std/numerics/c.math/abs.pass.cpp

   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
  17 template<class T>
  18 struct correct_size_int
  19 {
  20     typedef typename std::conditional<sizeof(T) < sizeof(int), int, T>::type type;
  21 };
  22
  23 template <class Source, class Result>
  24 void 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
  36 void 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
  46 int 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 }