123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238 |
- // 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_
|