text: /*
   * Copyright 2012 10gen Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  /**
   * // TODO: consider splitting out clang specific functionality
   * Compiler-specific implementations for gcc (and clang).
   *
   * Refer to mongo/platform/compiler.h for usage documentation.
   */
  
  #pragma once
  
  #define MONGO_COMPILER_NORETURN __attribute__((__noreturn__))
  
  #define MONGO_COMPILER_VARIABLE_UNUSED __attribute__((__unused__))
  
  #define MONGO_COMPILER_ALIGN_TYPE(ALIGNMENT) __attribute__((__aligned__(ALIGNMENT)))
  
  #define MONGO_COMPILER_ALIGN_VARIABLE(ALIGNMENT) __attribute__((__aligned__(ALIGNMENT)))
  
  // NOTE(schwerin): These visibility and calling-convention macro definitions assume we're not using
  // GCC/CLANG to target native Windows. If/when we decide to do such targeting, we'll need to change
  // compiler flags on Windows to make sure we use an appropriate calling convention, and configure
  // MONGO_COMPILER_API_EXPORT, MONGO_COMPILER_API_IMPORT and MONGO_COMPILER_API_CALLING_CONVENTION
  // correctly.  I believe "correctly" is the following:
  //
  // #ifdef _WIN32
  // #define MONGO_COMIPLER_API_EXPORT __attribute__(( __dllexport__ ))
  // #define MONGO_COMPILER_API_IMPORT __attribute__(( __dllimport__ ))
  // #ifdef _M_IX86
  // #define MONGO_COMPILER_API_CALLING_CONVENTION __attribute__((__cdecl__))
  // #else
  // #define MONGO_COMPILER_API_CALLING_CONVENTION
  // #endif
  // #else ... fall through to the definitions below.
  
  #define MONGO_COMPILER_API_EXPORT __attribute__((__visibility__("default")))
  #define MONGO_COMPILER_API_IMPORT
  #define MONGO_COMPILER_API_CALLING_CONVENTION
  
  // old versions of gcc and clang don't accept a message
  #ifdef __clang__
  
  // for compatibility with older versions of clang
  #ifndef __has_extension
  #define __has_extension __has_feature
  #endif
  
  // Technically __attribute__(deprecated) is supposed to come at the end of the declaration, but
  // GCC and clang accept it at the start, which eases compatibility with MSVC
  
  #if __has_extension(attribute_deprecated_with_message)
  #define MONGO_COMPILER_API_DEPRECATED(MSG) __attribute__((deprecated(MSG)))
  #else  // older clang doesn't support message
  #define MONGO_COMPILER_API_DEPRECATED(MSG) __attribute__((deprecated))
  #endif
  
  #else  // we are using GCC
  
  #if __GNUC__ > 4 || ((__GNUC__ == 4) && __GNUC_MINOR > 5)  // deprecation messages were added in 4.5
  #define MONGO_COMPILER_API_DEPRECATED(MSG) __attribute__((deprecated(MSG)))
  #else  // Older GCC doesn't support message
  #define MONGO_COMPILER_API_DEPRECATED(MSG) __attribute__((deprecated))
  #endif
  
  #endif
  
  #define MONGO_likely(x) static_cast<bool>(__builtin_expect(static_cast<bool>(x), 1))
  #define MONGO_unlikely(x) static_cast<bool>(__builtin_expect(static_cast<bool>(x), 0))
  