All pre-processor switches and configurations are all gathered
+ in the file c++config.h, which is generated during
+ the libstdc++ configuration and build process, and included by
+ files part of the public libstdc++ API. Most of these macros
+ should not be used by consumers of libstdc++, and are reserved
+ for internal implementation use. These macros cannot be
+ redefined. However, a select handful of these macro
+ control libstdc++ extensions and extra features, or provide
+ versioning information for the API, and are able to be used.
+
All library macros begin with _GLIBCXX_ (except for
+ versions 3.1.x to 3.3.x, which use _GLIBCPP_).
+
Below is the macro which users may check for library version + information.
__GLIBCXX__The current version of + libstdc++ in compressed ISO date format, form of an unsigned + long. For details on the value of this particular macro for a + particular release, please consult this + document. +
Below are the macros which users may change with #define/#undef or + with -D/-U compiler flags. The default state of the symbol is + listed.
âConfigurableâ (or âNot configurableâ) means + that the symbol is initially chosen (or not) based on + --enable/--disable options at library build and configure time + (documented here), with the + various --enable/--disable choices being translated to + #define/#undef). +
ABI means that changing from the default value may + mean changing the ABI of compiled code. In other words, these + choices control code which has already been compiled (i.e., in a + binary such as libstdc++.a/.so). If you explicitly #define or + #undef these macros, the headers may see different code + paths, but the libraries which you link against will not. + Experimenting with different values with the expectation of + consistent linkage requires changing the config headers before + building/installing the library. +
_GLIBCXX_DEPRECATED
+ Defined by default. Not configurable. ABI-changing. Turning this off
+ removes older ARM-style iostreams code, and other anachronisms
+ from the API. This macro is dependent on the version of the
+ standard being tracked, and as a result may give different results for
+ -std=c++98 and -std=c++0x. This may
+ be useful in updating old C++ code which no longer meet the
+ requirements of the language, or for checking current code
+ against new language standards.
+
_GLIBCXX_FORCE_NEW
+ Undefined by default. When defined, memory allocation and
+ allocators controlled by libstdc++ call operator new/delete
+ without caching and pooling. Configurable via
+ --enable-libstdcxx-allocator. ABI-changing.
+
_GLIBCXX_CONCEPT_CHECKS
+ Undefined by default. Configurable via
+ --enable-concept-checks. When defined, performs
+ compile-time checking on certain template instantiations to
+ detect violations of the requirements of the standard. This
+ is described in more detail here.
+
_GLIBCXX_DEBUG+ Undefined by default. When defined, compiles + user code using the libstdc++ debug + mode. +
_GLIBCXX_DEBUG_PEDANTIC+ Undefined by default. When defined while + compiling with the libstdc++ debug + mode, makes the debug mode extremely picky by making the use + of libstdc++ extensions and libstdc++-specific behavior into + errors. +
_GLIBCXX_PARALLELUndefined by default. When defined, compiles + user code using the libstdc++ parallel + mode. +