API Evolution and Deprecation History

A list of user-visible changes, in chronological order

Extensions moved to include/ext.

Include files from the SGI/HP sources that pre-date the ISO standard are added. These files are placed into the include/backward directory and a deprecated warning is added that notifies on inclusion (-Wno-deprecated deactivates the warning.)

Deprecated include backward/strstream added.

Removal of include builtinbuf.h, indstream.h, parsestream.h, PlotFile.h, SFile.h, stdiostream.h, and stream.h.

Extensions from SGI/HP moved from namespace std to namespace __gnu_cxx. As part of this, the following new includes are added: ext/algorithm, ext/functional, ext/iterator, ext/memory, and ext/numeric.

Extensions to basic_filebuf introduced: __gnu_cxx::enc_filebuf, and __gnu_cxx::stdio_filebuf.

Extensions to tree data structures added in ext/rb_tree.

Removal of ext/tree, moved to backward/tree.h.

Symbol versioning introduced for shared library.

Removal of include backward/strstream.h.

Allocator changes. Change __malloc_alloc to malloc_allocator and __new_alloc to new_allocator.

For GCC releases from 2.95 through the 3.1 series, defining __USE_MALLOC on the gcc command line would change the default allocation strategy to instead use malloc and free. (This same functionality is now spelled _GLIBCXX_FORCE_NEW, see this page for details.

Error handling in iostreams cleaned up, made consistent.

Large file support.

Extensions for generic characters and char_traits added in ext/pod_char_traits.h.

Support for wchar_t specializations of basic_filebuf enhanced to support UTF-8 and Unicode, depending on host. More hosts support basic wchar_t functionality.

Support for char_traits beyond builtin types.

Conformant allocator class and usage in containers. As part of this, the following extensions are added: ext/bitmap_allocator.h, ext/debug_allocator.h, ext/mt_allocator.h, ext/malloc_allocator.h,ext/new_allocator.h, ext/pool_allocator.h.

This is a change from all previous versions, and may require source-level changes due to allocator-related changes to structures names and template parameters, filenames, and file locations. Some, like __simple_alloc, __allocator, __alloc, and _Alloc_traits have been removed.

Default behavior of std::allocator has changed.

Previous versions prior to 3.4 cache allocations in a memory pool, instead of passing through to call the global allocation operators (i.e., __gnu_cxx::pool_allocator). More recent versions default to the simpler __gnu_cxx::new_allocator.

Previously, all allocators were written to the SGI style, and all STL containers expected this interface. This interface had a traits class called _Alloc_traits that attempted to provide more information for compile-time allocation selection and optimization. This traits class had another allocator wrapper, __simple_alloc<T,A>, which was a wrapper around another allocator, A, which itself is an allocator for instances of T. But wait, there's more: __allocator<T,A> is another adapter. Many of the provided allocator classes were SGI style: such classes can be changed to a conforming interface with this wrapper: __allocator<T, __alloc> is thus the same as allocator<T>.

The class allocator used the typedef __alloc to select an underlying allocator that satisfied memory allocation requests. The selection of this underlying allocator was not user-configurable.

Releases after gcc-3.4 have continued to add to the collection of available allocators. All of these new allocators are standard-style. The following table includes details, along with the first released version of GCC that included the extension allocator.

Debug mode first appears.

Precompiled header support PCH support.

Macro guard for changed, from _GLIBCPP_ to _GLIBCXX_.

Extension ext/stdio_sync_filebuf.h added.

Extension ext/demangle.h added.

TR1 features first appear.

Extension allocator ext/array_allocator.h added.

Extension codecvt specializations moved to ext/codecvt_specializations.h.

Removal of ext/demangle.h.

Removal of cassert from all standard headers: now has to be explicitly included for std::assert calls.

Extensions for policy-based data structures first added. New includes, types, namespace pb_assoc.

Extensions for typelists added in ext/typelist.h.

Extension for policy-based basic_string first added: __gnu_cxx::__versa_string in ext/vstring.h.

Default visibility attributes applied to namespace std. Support for -fvisibility.

TR1 random, complex, and C compatibility headers added.

Extensions for concurrent programming consolidated into ext/concurrence.h and ext/atomicity.h, including change of namespace to __gnu_cxx in some cases. Added types include _Lock_policy, __concurrence_lock_error, __concurrence_unlock_error, __mutex, __scoped_lock.

Extensions for type traits consolidated into ext/type_traits.h. Additional traits are added (__conditional_type, __enable_if, others.)

Extensions for policy-based data structures revised. New includes, types, namespace moved to __pb_ds.

Extensions for debug mode modified: now nested in namespace std::__debug and extensions in namespace __gnu_cxx::__debug.

Extensions added: ext/typelist.h and ext/throw_allocator.h.

C++0X features first appear.

TR1 regex and cmath's mathematical special function added.

Backward include edit.

Header dependency streamlining.

Debug mode for unordered_map and unordered_set.

Parallel mode first appears.

Variadic template implementations of items in tuple and functional.

Default what implementations give more elaborate exception strings for bad_cast, bad_typeid, bad_exception, and bad_alloc.

PCH binary files no longer installed. Instead, the source files are installed.

Namespace pb_ds moved to __gnu_pb_ds.

C++0X features.

Uglification of try to __try and catch to __catch.

Audit of internal mutex usage, conversion to functions returning static local mutex.

Extensions added: ext/pointer.h and ext/extptr_allocator.h. Support for non-standard pointer types has been added to vector and forward_list.

C++0X features.

Profile mode first appears.

Support for decimal floating-point arithmetic, including decimal32, decimal64, and decimal128.

Python pretty-printers are added for use with appropriately-advanced versions of gdb.

Audit for application of function attributes notrow, const, pure, and noreturn.

The default behavior for comparing typeinfo names changed, so in typeinfo, __GXX_MERGED_TYPEINFO_NAMES now defaults to zero.

Extensions modified: ext/throw_allocator.h.