1 // Copyright 2023 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 #ifndef ABSL_BASE_INTERNAL_NULLABILITY_IMPL_H_ 16 #define ABSL_BASE_INTERNAL_NULLABILITY_IMPL_H_ 17 18 #include <memory> 19 #include <type_traits> 20 21 #include "absl/base/attributes.h" 22 #include "absl/base/config.h" 23 #include "absl/meta/type_traits.h" 24 25 namespace absl { 26 ABSL_NAMESPACE_BEGIN 27 namespace nullability_internal { 28 29 template <typename T> 30 using NullableImpl 31 #if ABSL_HAVE_CPP_ATTRIBUTE(clang::annotate) 32 [[clang::annotate("Nullable")]] 33 #endif 34 // Don't add the _Nullable attribute in Objective-C compiles. Many Objective-C 35 // projects enable the `-Wnullable-to-nonnull-conversion warning`, which is 36 // liable to produce false positives. 37 #if ABSL_HAVE_FEATURE(nullability_on_classes) && !defined(__OBJC__) 38 = T _Nullable; 39 #else 40 = T; 41 #endif 42 43 template <typename T> 44 using NonnullImpl 45 #if ABSL_HAVE_CPP_ATTRIBUTE(clang::annotate) 46 [[clang::annotate("Nonnull")]] 47 #endif 48 #if ABSL_HAVE_FEATURE(nullability_on_classes) && !defined(__OBJC__) 49 = T _Nonnull; 50 #else 51 = T; 52 #endif 53 54 template <typename T> 55 using NullabilityUnknownImpl 56 #if ABSL_HAVE_CPP_ATTRIBUTE(clang::annotate) 57 [[clang::annotate("Nullability_Unspecified")]] 58 #endif 59 #if ABSL_HAVE_FEATURE(nullability_on_classes) && !defined(__OBJC__) 60 = T _Null_unspecified; 61 #else 62 = T; 63 #endif 64 65 } // namespace nullability_internal 66 ABSL_NAMESPACE_END 67 } // namespace absl 68 69 #endif // ABSL_BASE_INTERNAL_NULLABILITY_IMPL_H_ 70