log/internal/voidify.h

0001 // Copyright 2022 The Abseil Authors.
0002 //
0003 // Licensed under the Apache License, Version 2.0 (the "License");
0004 // you may not use this file except in compliance with the License.
0005 // You may obtain a copy of the License at
0006 //
0007 //      https://www.apache.org/licenses/LICENSE-2.0
0008 //
0009 // Unless required by applicable law or agreed to in writing, software
0010 // distributed under the License is distributed on an "AS IS" BASIS,
0011 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
0012 // See the License for the specific language governing permissions and
0013 // limitations under the License.
0014 //
0015 // -----------------------------------------------------------------------------
0016 // File: log/internal/voidify.h
0017 // -----------------------------------------------------------------------------
0018 //
0019 // This class is used to explicitly ignore values in the conditional logging
0020 // macros. This avoids compiler warnings like "value computed is not used" and
0021 // "statement has no effect".
0022
0023 #ifndef ABSL_LOG_INTERNAL_VOIDIFY_H_
0024 #define ABSL_LOG_INTERNAL_VOIDIFY_H_
0025
0026 #include "absl/base/config.h"
0027
0028 namespace absl {
0029 ABSL_NAMESPACE_BEGIN
0030 namespace log_internal {
0031
0032 class Voidify final {
0033  public:
0034   // This has to be an operator with a precedence lower than << but higher than
0035   // ?:
0036   template <typename T>
0037   void operator&&(const T&) const&& {}
0038 };
0039
0040 }  // namespace log_internal
0041 ABSL_NAMESPACE_END
0042 }  // namespace absl
0043
0044 #endif  // ABSL_LOG_INTERNAL_VOIDIFY_H_