1 // Copyright 2017 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "absl/random/internal/traits.h"
16
17 #include <cstdint>
18 #include <type_traits>
19
20 #include "gtest/gtest.h"
21
22 namespace {
23
24 using absl::random_internal::is_widening_convertible;
25
26 // CheckWideningConvertsToSelf<T1, T2, ...>()
27 //
28 // For each type T, checks:
29 // - T IS widening-convertible to itself.
30 //
31 template <typename T>
CheckWideningConvertsToSelf()32 void CheckWideningConvertsToSelf() {
33 static_assert(is_widening_convertible<T, T>::value,
34 "Type is not convertible to self!");
35 }
36
37 template <typename T, typename Next, typename... Args>
CheckWideningConvertsToSelf()38 void CheckWideningConvertsToSelf() {
39 CheckWideningConvertsToSelf<T>();
40 CheckWideningConvertsToSelf<Next, Args...>();
41 }
42
43 // CheckNotWideningConvertibleWithSigned<T1, T2, ...>()
44 //
45 // For each unsigned-type T, checks that:
46 // - T is NOT widening-convertible to Signed(T)
47 // - Signed(T) is NOT widening-convertible to T
48 //
49 template <typename T>
CheckNotWideningConvertibleWithSigned()50 void CheckNotWideningConvertibleWithSigned() {
51 using signed_t = typename std::make_signed<T>::type;
52
53 static_assert(!is_widening_convertible<T, signed_t>::value,
54 "Unsigned type is convertible to same-sized signed-type!");
55 static_assert(!is_widening_convertible<signed_t, T>::value,
56 "Signed type is convertible to same-sized unsigned-type!");
57 }
58
59 template <typename T, typename Next, typename... Args>
CheckNotWideningConvertibleWithSigned()60 void CheckNotWideningConvertibleWithSigned() {
61 CheckNotWideningConvertibleWithSigned<T>();
62 CheckWideningConvertsToSelf<Next, Args...>();
63 }
64
65 // CheckWideningConvertsToLargerType<T1, T2, ...>()
66 //
67 // For each successive unsigned-types {Ti, Ti+1}, checks that:
68 // - Ti IS widening-convertible to Ti+1
69 // - Ti IS widening-convertible to Signed(Ti+1)
70 // - Signed(Ti) is NOT widening-convertible to Ti
71 // - Signed(Ti) IS widening-convertible to Ti+1
72 template <typename T, typename Higher>
CheckWideningConvertsToLargerTypes()73 void CheckWideningConvertsToLargerTypes() {
74 using signed_t = typename std::make_signed<T>::type;
75 using higher_t = Higher;
76 using signed_higher_t = typename std::make_signed<Higher>::type;
77
78 static_assert(is_widening_convertible<T, higher_t>::value,
79 "Type not embeddable into larger type!");
80 static_assert(is_widening_convertible<T, signed_higher_t>::value,
81 "Type not embeddable into larger signed type!");
82 static_assert(!is_widening_convertible<signed_t, higher_t>::value,
83 "Signed type is embeddable into larger unsigned type!");
84 static_assert(is_widening_convertible<signed_t, signed_higher_t>::value,
85 "Signed type not embeddable into larger signed type!");
86 }
87
88 template <typename T, typename Higher, typename Next, typename... Args>
CheckWideningConvertsToLargerTypes()89 void CheckWideningConvertsToLargerTypes() {
90 CheckWideningConvertsToLargerTypes<T, Higher>();
91 CheckWideningConvertsToLargerTypes<Higher, Next, Args...>();
92 }
93
94 // CheckWideningConvertsTo<T, U, [expect]>
95 //
96 // Checks that T DOES widening-convert to U.
97 // If "expect" is false, then asserts that T does NOT widening-convert to U.
98 template <typename T, typename U, bool expect = true>
CheckWideningConvertsTo()99 void CheckWideningConvertsTo() {
100 static_assert(is_widening_convertible<T, U>::value == expect,
101 "Unexpected result for is_widening_convertible<T, U>!");
102 }
103
TEST(TraitsTest,IsWideningConvertibleTest)104 TEST(TraitsTest, IsWideningConvertibleTest) {
105 constexpr bool kInvalid = false;
106
107 CheckWideningConvertsToSelf<
108 uint8_t, uint16_t, uint32_t, uint64_t,
109 int8_t, int16_t, int32_t, int64_t,
110 float, double>();
111 CheckNotWideningConvertibleWithSigned<
112 uint8_t, uint16_t, uint32_t, uint64_t>();
113 CheckWideningConvertsToLargerTypes<
114 uint8_t, uint16_t, uint32_t, uint64_t>();
115
116 CheckWideningConvertsTo<float, double>();
117 CheckWideningConvertsTo<uint16_t, float>();
118 CheckWideningConvertsTo<uint32_t, double>();
119 CheckWideningConvertsTo<uint64_t, double, kInvalid>();
120 CheckWideningConvertsTo<double, float, kInvalid>();
121
122 CheckWideningConvertsTo<bool, int>();
123 CheckWideningConvertsTo<bool, float>();
124 }
125
126 } // namespace
127