239 lines
11 KiB
C++
239 lines
11 KiB
C++
// Copyright 2019 The Abseil Authors.
|
|
//
|
|
// 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
|
|
//
|
|
// https://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.
|
|
//
|
|
// -----------------------------------------------------------------------------
|
|
// File: options.h
|
|
// -----------------------------------------------------------------------------
|
|
//
|
|
// This file contains Abseil configuration options for setting specific
|
|
// implementations instead of letting Abseil determine which implementation to
|
|
// use at compile-time. Setting these options may be useful for package or build
|
|
// managers who wish to guarantee ABI stability within binary builds (which are
|
|
// otherwise difficult to enforce).
|
|
//
|
|
// *** IMPORTANT NOTICE FOR PACKAGE MANAGERS: It is important that
|
|
// maintainers of package managers who wish to package Abseil read and
|
|
// understand this file! ***
|
|
//
|
|
// Abseil contains a number of possible configuration endpoints, based on
|
|
// parameters such as the detected platform, language version, or command-line
|
|
// flags used to invoke the underlying binary. As is the case with all
|
|
// libraries, binaries which contain Abseil code must ensure that separate
|
|
// packages use the same compiled copy of Abseil to avoid a diamond dependency
|
|
// problem, which can occur if two packages built with different Abseil
|
|
// configuration settings are linked together. Diamond dependency problems in
|
|
// C++ may manifest as violations to the One Definition Rule (ODR) (resulting in
|
|
// linker errors), or undefined behavior (resulting in crashes).
|
|
//
|
|
// Diamond dependency problems can be avoided if all packages utilize the same
|
|
// exact version of Abseil. Building from source code with the same compilation
|
|
// parameters is the easiest way to avoid such dependency problems. However, for
|
|
// package managers who cannot control such compilation parameters, we are
|
|
// providing the file to allow you to inject ABI (Application Binary Interface)
|
|
// stability across builds. Settings options in this file will neither change
|
|
// API nor ABI, providing a stable copy of Abseil between packages.
|
|
//
|
|
// Care must be taken to keep options within these configurations isolated
|
|
// from any other dynamic settings, such as command-line flags which could alter
|
|
// these options. This file is provided specifically to help build and package
|
|
// managers provide a stable copy of Abseil within their libraries and binaries;
|
|
// other developers should not have need to alter the contents of this file.
|
|
//
|
|
// -----------------------------------------------------------------------------
|
|
// Usage
|
|
// -----------------------------------------------------------------------------
|
|
//
|
|
// For any particular package release, set the appropriate definitions within
|
|
// this file to whatever value makes the most sense for your package(s). Note
|
|
// that, by default, most of these options, at the moment, affect the
|
|
// implementation of types; future options may affect other implementation
|
|
// details.
|
|
//
|
|
// NOTE: the defaults within this file all assume that Abseil can select the
|
|
// proper Abseil implementation at compile-time, which will not be sufficient
|
|
// to guarantee ABI stability to package managers.
|
|
|
|
#ifndef ABSL_BASE_OPTIONS_H_
|
|
#define ABSL_BASE_OPTIONS_H_
|
|
|
|
// Include a standard library header to allow configuration based on the
|
|
// standard library in use.
|
|
#ifdef __cplusplus
|
|
#include <ciso646>
|
|
#endif
|
|
|
|
// -----------------------------------------------------------------------------
|
|
// Type Compatibility Options
|
|
// -----------------------------------------------------------------------------
|
|
//
|
|
// ABSL_OPTION_USE_STD_ANY
|
|
//
|
|
// This option controls whether absl::any is implemented as an alias to
|
|
// std::any, or as an independent implementation.
|
|
//
|
|
// A value of 0 means to use Abseil's implementation. This requires only C++11
|
|
// support, and is expected to work on every toolchain we support.
|
|
//
|
|
// A value of 1 means to use an alias to std::any. This requires that all code
|
|
// using Abseil is built in C++17 mode or later.
|
|
//
|
|
// A value of 2 means to detect the C++ version being used to compile Abseil,
|
|
// and use an alias only if a working std::any is available. This option is
|
|
// useful when you are building your entire program, including all of its
|
|
// dependencies, from source. It should not be used otherwise -- for example,
|
|
// if you are distributing Abseil in a binary package manager -- since in
|
|
// mode 2, absl::any will name a different type, with a different mangled name
|
|
// and binary layout, depending on the compiler flags passed by the end user.
|
|
// For more info, see https://abseil.io/about/design/dropin-types.
|
|
//
|
|
// User code should not inspect this macro. To check in the preprocessor if
|
|
// absl::any is a typedef of std::any, use the feature macro ABSL_USES_STD_ANY.
|
|
|
|
#define ABSL_OPTION_USE_STD_ANY 2
|
|
|
|
|
|
// ABSL_OPTION_USE_STD_OPTIONAL
|
|
//
|
|
// This option controls whether absl::optional is implemented as an alias to
|
|
// std::optional, or as an independent implementation.
|
|
//
|
|
// A value of 0 means to use Abseil's implementation. This requires only C++11
|
|
// support, and is expected to work on every toolchain we support.
|
|
//
|
|
// A value of 1 means to use an alias to std::optional. This requires that all
|
|
// code using Abseil is built in C++17 mode or later.
|
|
//
|
|
// A value of 2 means to detect the C++ version being used to compile Abseil,
|
|
// and use an alias only if a working std::optional is available. This option
|
|
// is useful when you are building your program from source. It should not be
|
|
// used otherwise -- for example, if you are distributing Abseil in a binary
|
|
// package manager -- since in mode 2, absl::optional will name a different
|
|
// type, with a different mangled name and binary layout, depending on the
|
|
// compiler flags passed by the end user. For more info, see
|
|
// https://abseil.io/about/design/dropin-types.
|
|
|
|
// User code should not inspect this macro. To check in the preprocessor if
|
|
// absl::optional is a typedef of std::optional, use the feature macro
|
|
// ABSL_USES_STD_OPTIONAL.
|
|
|
|
#define ABSL_OPTION_USE_STD_OPTIONAL 2
|
|
|
|
|
|
// ABSL_OPTION_USE_STD_STRING_VIEW
|
|
//
|
|
// This option controls whether absl::string_view is implemented as an alias to
|
|
// std::string_view, or as an independent implementation.
|
|
//
|
|
// A value of 0 means to use Abseil's implementation. This requires only C++11
|
|
// support, and is expected to work on every toolchain we support.
|
|
//
|
|
// A value of 1 means to use an alias to std::string_view. This requires that
|
|
// all code using Abseil is built in C++17 mode or later.
|
|
//
|
|
// A value of 2 means to detect the C++ version being used to compile Abseil,
|
|
// and use an alias only if a working std::string_view is available. This
|
|
// option is useful when you are building your program from source. It should
|
|
// not be used otherwise -- for example, if you are distributing Abseil in a
|
|
// binary package manager -- since in mode 2, absl::string_view will name a
|
|
// different type, with a different mangled name and binary layout, depending on
|
|
// the compiler flags passed by the end user. For more info, see
|
|
// https://abseil.io/about/design/dropin-types.
|
|
//
|
|
// User code should not inspect this macro. To check in the preprocessor if
|
|
// absl::string_view is a typedef of std::string_view, use the feature macro
|
|
// ABSL_USES_STD_STRING_VIEW.
|
|
|
|
#define ABSL_OPTION_USE_STD_STRING_VIEW 2
|
|
|
|
// ABSL_OPTION_USE_STD_VARIANT
|
|
//
|
|
// This option controls whether absl::variant is implemented as an alias to
|
|
// std::variant, or as an independent implementation.
|
|
//
|
|
// A value of 0 means to use Abseil's implementation. This requires only C++11
|
|
// support, and is expected to work on every toolchain we support.
|
|
//
|
|
// A value of 1 means to use an alias to std::variant. This requires that all
|
|
// code using Abseil is built in C++17 mode or later.
|
|
//
|
|
// A value of 2 means to detect the C++ version being used to compile Abseil,
|
|
// and use an alias only if a working std::variant is available. This option
|
|
// is useful when you are building your program from source. It should not be
|
|
// used otherwise -- for example, if you are distributing Abseil in a binary
|
|
// package manager -- since in mode 2, absl::variant will name a different
|
|
// type, with a different mangled name and binary layout, depending on the
|
|
// compiler flags passed by the end user. For more info, see
|
|
// https://abseil.io/about/design/dropin-types.
|
|
//
|
|
// User code should not inspect this macro. To check in the preprocessor if
|
|
// absl::variant is a typedef of std::variant, use the feature macro
|
|
// ABSL_USES_STD_VARIANT.
|
|
|
|
#define ABSL_OPTION_USE_STD_VARIANT 2
|
|
|
|
|
|
// ABSL_OPTION_USE_INLINE_NAMESPACE
|
|
// ABSL_OPTION_INLINE_NAMESPACE_NAME
|
|
//
|
|
// These options controls whether all entities in the absl namespace are
|
|
// contained within an inner inline namespace. This does not affect the
|
|
// user-visible API of Abseil, but it changes the mangled names of all symbols.
|
|
//
|
|
// This can be useful as a version tag if you are distributing Abseil in
|
|
// precompiled form. This will prevent a binary library build of Abseil with
|
|
// one inline namespace being used with headers configured with a different
|
|
// inline namespace name. Binary packagers are reminded that Abseil does not
|
|
// guarantee any ABI stability in Abseil, so any update of Abseil or
|
|
// configuration change in such a binary package should be combined with a
|
|
// new, unique value for the inline namespace name.
|
|
//
|
|
// A value of 0 means not to use inline namespaces.
|
|
//
|
|
// A value of 1 means to use an inline namespace with the given name inside
|
|
// namespace absl. If this is set, ABSL_OPTION_INLINE_NAMESPACE_NAME must also
|
|
// be changed to a new, unique identifier name. In particular "head" is not
|
|
// allowed.
|
|
|
|
#define ABSL_OPTION_USE_INLINE_NAMESPACE 0
|
|
#define ABSL_OPTION_INLINE_NAMESPACE_NAME head
|
|
|
|
// ABSL_OPTION_HARDENED
|
|
//
|
|
// This option enables a "hardened" build in release mode (in this context,
|
|
// release mode is defined as a build where the `NDEBUG` macro is defined).
|
|
//
|
|
// A value of 0 means that "hardened" mode is not enabled.
|
|
//
|
|
// A value of 1 means that "hardened" mode is enabled.
|
|
//
|
|
// Hardened builds have additional security checks enabled when `NDEBUG` is
|
|
// defined. Defining `NDEBUG` is normally used to turn `assert()` macro into a
|
|
// no-op, as well as disabling other bespoke program consistency checks. By
|
|
// defining ABSL_OPTION_HARDENED to 1, a select set of checks remain enabled in
|
|
// release mode. These checks guard against programming errors that may lead to
|
|
// security vulnerabilities. In release mode, when one of these programming
|
|
// errors is encountered, the program will immediately abort, possibly without
|
|
// any attempt at logging.
|
|
//
|
|
// The checks enabled by this option are not free; they do incur runtime cost.
|
|
//
|
|
// The checks enabled by this option are always active when `NDEBUG` is not
|
|
// defined, even in the case when ABSL_OPTION_HARDENED is defined to 0. The
|
|
// checks enabled by this option may abort the program in a different way and
|
|
// log additional information when `NDEBUG` is not defined.
|
|
|
|
#define ABSL_OPTION_HARDENED 1
|
|
|
|
#endif // ABSL_BASE_OPTIONS_H_
|