options.h 12 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258
  1. // Copyright 2019 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. // -----------------------------------------------------------------------------
  16. // File: options.h
  17. // -----------------------------------------------------------------------------
  18. //
  19. // This file contains Abseil configuration options for setting specific
  20. // implementations instead of letting Abseil determine which implementation to
  21. // use at compile-time. Setting these options may be useful for package or build
  22. // managers who wish to guarantee ABI stability within binary builds (which are
  23. // otherwise difficult to enforce).
  24. //
  25. // *** IMPORTANT NOTICE FOR PACKAGE MANAGERS: It is important that
  26. // maintainers of package managers who wish to package Abseil read and
  27. // understand this file! ***
  28. //
  29. // Abseil contains a number of possible configuration endpoints, based on
  30. // parameters such as the detected platform, language version, or command-line
  31. // flags used to invoke the underlying binary. As is the case with all
  32. // libraries, binaries which contain Abseil code must ensure that separate
  33. // packages use the same compiled copy of Abseil to avoid a diamond dependency
  34. // problem, which can occur if two packages built with different Abseil
  35. // configuration settings are linked together. Diamond dependency problems in
  36. // C++ may manifest as violations to the One Definition Rule (ODR) (resulting in
  37. // linker errors), or undefined behavior (resulting in crashes).
  38. //
  39. // Diamond dependency problems can be avoided if all packages utilize the same
  40. // exact version of Abseil. Building from source code with the same compilation
  41. // parameters is the easiest way to avoid such dependency problems. However, for
  42. // package managers who cannot control such compilation parameters, we are
  43. // providing the file to allow you to inject ABI (Application Binary Interface)
  44. // stability across builds. Settings options in this file will neither change
  45. // API nor ABI, providing a stable copy of Abseil between packages.
  46. //
  47. // Care must be taken to keep options within these configurations isolated
  48. // from any other dynamic settings, such as command-line flags which could alter
  49. // these options. This file is provided specifically to help build and package
  50. // managers provide a stable copy of Abseil within their libraries and binaries;
  51. // other developers should not have need to alter the contents of this file.
  52. //
  53. // -----------------------------------------------------------------------------
  54. // Usage
  55. // -----------------------------------------------------------------------------
  56. //
  57. // For any particular package release, set the appropriate definitions within
  58. // this file to whatever value makes the most sense for your package(s). Note
  59. // that, by default, most of these options, at the moment, affect the
  60. // implementation of types; future options may affect other implementation
  61. // details.
  62. //
  63. // NOTE: the defaults within this file all assume that Abseil can select the
  64. // proper Abseil implementation at compile-time, which will not be sufficient
  65. // to guarantee ABI stability to package managers.
  66. #ifndef ABSL_BASE_OPTIONS_H_
  67. #define ABSL_BASE_OPTIONS_H_
  68. // -----------------------------------------------------------------------------
  69. // Type Compatibility Options
  70. // -----------------------------------------------------------------------------
  71. //
  72. // ABSL_OPTION_USE_STD_ANY
  73. //
  74. // This option controls whether absl::any is implemented as an alias to
  75. // std::any, or as an independent implementation.
  76. //
  77. // A value of 0 means to use Abseil's implementation. This requires only C++11
  78. // support, and is expected to work on every toolchain we support.
  79. //
  80. // A value of 1 means to use an alias to std::any. This requires that all code
  81. // using Abseil is built in C++17 mode or later.
  82. //
  83. // A value of 2 means to detect the C++ version being used to compile Abseil,
  84. // and use an alias only if a working std::any is available. This option is
  85. // useful when you are building your entire program, including all of its
  86. // dependencies, from source. It should not be used otherwise -- for example,
  87. // if you are distributing Abseil in a binary package manager -- since in
  88. // mode 2, absl::any will name a different type, with a different mangled name
  89. // and binary layout, depending on the compiler flags passed by the end user.
  90. // For more info, see https://abseil.io/about/design/dropin-types.
  91. //
  92. // User code should not inspect this macro. To check in the preprocessor if
  93. // absl::any is a typedef of std::any, use the feature macro ABSL_USES_STD_ANY.
  94. #define ABSL_OPTION_USE_STD_ANY 2
  95. // ABSL_OPTION_USE_STD_OPTIONAL
  96. //
  97. // This option controls whether absl::optional is implemented as an alias to
  98. // std::optional, or as an independent implementation.
  99. //
  100. // A value of 0 means to use Abseil's implementation. This requires only C++11
  101. // support, and is expected to work on every toolchain we support.
  102. //
  103. // A value of 1 means to use an alias to std::optional. This requires that all
  104. // code using Abseil is built in C++17 mode or later.
  105. //
  106. // A value of 2 means to detect the C++ version being used to compile Abseil,
  107. // and use an alias only if a working std::optional is available. This option
  108. // is useful when you are building your program from source. It should not be
  109. // used otherwise -- for example, if you are distributing Abseil in a binary
  110. // package manager -- since in mode 2, absl::optional will name a different
  111. // type, with a different mangled name and binary layout, depending on the
  112. // compiler flags passed by the end user. For more info, see
  113. // https://abseil.io/about/design/dropin-types.
  114. // User code should not inspect this macro. To check in the preprocessor if
  115. // absl::optional is a typedef of std::optional, use the feature macro
  116. // ABSL_USES_STD_OPTIONAL.
  117. #define ABSL_OPTION_USE_STD_OPTIONAL 2
  118. // ABSL_OPTION_USE_STD_STRING_VIEW
  119. //
  120. // This option controls whether absl::string_view is implemented as an alias to
  121. // std::string_view, or as an independent implementation.
  122. //
  123. // A value of 0 means to use Abseil's implementation. This requires only C++11
  124. // support, and is expected to work on every toolchain we support.
  125. //
  126. // A value of 1 means to use an alias to std::string_view. This requires that
  127. // all code using Abseil is built in C++17 mode or later.
  128. //
  129. // A value of 2 means to detect the C++ version being used to compile Abseil,
  130. // and use an alias only if a working std::string_view is available. This
  131. // option is useful when you are building your program from source. It should
  132. // not be used otherwise -- for example, if you are distributing Abseil in a
  133. // binary package manager -- since in mode 2, absl::string_view will name a
  134. // different type, with a different mangled name and binary layout, depending on
  135. // the compiler flags passed by the end user. For more info, see
  136. // https://abseil.io/about/design/dropin-types.
  137. //
  138. // User code should not inspect this macro. To check in the preprocessor if
  139. // absl::string_view is a typedef of std::string_view, use the feature macro
  140. // ABSL_USES_STD_STRING_VIEW.
  141. #define ABSL_OPTION_USE_STD_STRING_VIEW 2
  142. // ABSL_OPTION_USE_STD_VARIANT
  143. //
  144. // This option controls whether absl::variant is implemented as an alias to
  145. // std::variant, or as an independent implementation.
  146. //
  147. // A value of 0 means to use Abseil's implementation. This requires only C++11
  148. // support, and is expected to work on every toolchain we support.
  149. //
  150. // A value of 1 means to use an alias to std::variant. This requires that all
  151. // code using Abseil is built in C++17 mode or later.
  152. //
  153. // A value of 2 means to detect the C++ version being used to compile Abseil,
  154. // and use an alias only if a working std::variant is available. This option
  155. // is useful when you are building your program from source. It should not be
  156. // used otherwise -- for example, if you are distributing Abseil in a binary
  157. // package manager -- since in mode 2, absl::variant will name a different
  158. // type, with a different mangled name and binary layout, depending on the
  159. // compiler flags passed by the end user. For more info, see
  160. // https://abseil.io/about/design/dropin-types.
  161. //
  162. // User code should not inspect this macro. To check in the preprocessor if
  163. // absl::variant is a typedef of std::variant, use the feature macro
  164. // ABSL_USES_STD_VARIANT.
  165. #define ABSL_OPTION_USE_STD_VARIANT 2
  166. // ABSL_OPTION_USE_STD_ORDERING
  167. //
  168. // This option controls whether absl::{partial,weak,strong}_ordering are
  169. // implemented as aliases to the std:: ordering types, or as an independent
  170. // implementation.
  171. //
  172. // A value of 0 means to use Abseil's implementation. This requires only C++11
  173. // support, and is expected to work on every toolchain we support.
  174. //
  175. // A value of 1 means to use aliases. This requires that all code using Abseil
  176. // is built in C++20 mode or later.
  177. //
  178. // A value of 2 means to detect the C++ version being used to compile Abseil,
  179. // and use an alias only if working std:: ordering types are available. This
  180. // option is useful when you are building your program from source. It should
  181. // not be used otherwise -- for example, if you are distributing Abseil in a
  182. // binary package manager -- since in mode 2, they will name different types,
  183. // with different mangled names and binary layout, depending on the compiler
  184. // flags passed by the end user. For more info, see
  185. // https://abseil.io/about/design/dropin-types.
  186. //
  187. // User code should not inspect this macro. To check in the preprocessor if
  188. // the ordering types are aliases of std:: ordering types, use the feature macro
  189. // ABSL_USES_STD_ORDERING.
  190. #define ABSL_OPTION_USE_STD_ORDERING 2
  191. // ABSL_OPTION_USE_INLINE_NAMESPACE
  192. // ABSL_OPTION_INLINE_NAMESPACE_NAME
  193. //
  194. // These options controls whether all entities in the absl namespace are
  195. // contained within an inner inline namespace. This does not affect the
  196. // user-visible API of Abseil, but it changes the mangled names of all symbols.
  197. //
  198. // This can be useful as a version tag if you are distributing Abseil in
  199. // precompiled form. This will prevent a binary library build of Abseil with
  200. // one inline namespace being used with headers configured with a different
  201. // inline namespace name. Binary packagers are reminded that Abseil does not
  202. // guarantee any ABI stability in Abseil, so any update of Abseil or
  203. // configuration change in such a binary package should be combined with a
  204. // new, unique value for the inline namespace name.
  205. //
  206. // A value of 0 means not to use inline namespaces.
  207. //
  208. // A value of 1 means to use an inline namespace with the given name inside
  209. // namespace absl. If this is set, ABSL_OPTION_INLINE_NAMESPACE_NAME must also
  210. // be changed to a new, unique identifier name. In particular "head" is not
  211. // allowed.
  212. #define ABSL_OPTION_USE_INLINE_NAMESPACE 1
  213. #define ABSL_OPTION_INLINE_NAMESPACE_NAME lts_20240722
  214. // ABSL_OPTION_HARDENED
  215. //
  216. // This option enables a "hardened" build in release mode (in this context,
  217. // release mode is defined as a build where the `NDEBUG` macro is defined).
  218. //
  219. // A value of 0 means that "hardened" mode is not enabled.
  220. //
  221. // A value of 1 means that "hardened" mode is enabled.
  222. //
  223. // Hardened builds have additional security checks enabled when `NDEBUG` is
  224. // defined. Defining `NDEBUG` is normally used to turn `assert()` macro into a
  225. // no-op, as well as disabling other bespoke program consistency checks. By
  226. // defining ABSL_OPTION_HARDENED to 1, a select set of checks remain enabled in
  227. // release mode. These checks guard against programming errors that may lead to
  228. // security vulnerabilities. In release mode, when one of these programming
  229. // errors is encountered, the program will immediately abort, possibly without
  230. // any attempt at logging.
  231. //
  232. // The checks enabled by this option are not free; they do incur runtime cost.
  233. //
  234. // The checks enabled by this option are always active when `NDEBUG` is not
  235. // defined, even in the case when ABSL_OPTION_HARDENED is defined to 0. The
  236. // checks enabled by this option may abort the program in a different way and
  237. // log additional information when `NDEBUG` is not defined.
  238. #define ABSL_OPTION_HARDENED 0
  239. #endif // ABSL_BASE_OPTIONS_H_