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
. For the 3.2 and 3.3 release series the same
functionality was spelled _GLIBCXX_FORCE_NEW
. From
GCC 3.4 onwards the default allocator uses new
anyway,
but for the optional pooling allocators the functionality is enabled by
setting GLIBCXX_FORCE_NEW
in the environment, see
the mt allocator chapter
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.
Table B.6. Extension Allocators
Allocator (3.4) | Header (3.4) | Allocator (3.[0-3]) | Header (3.[0-3]) |
---|---|---|---|
__gnu_cxx::new_allocator<T> | <ext/new_allocator.h> | std::__new_alloc | <memory> |
__gnu_cxx::malloc_allocator<T> | <ext/malloc_allocator.h> | std::__malloc_alloc_template<int> | <memory> |
__gnu_cxx::debug_allocator<T> | <ext/debug_allocator.h> | std::debug_alloc<T> | <memory> |
__gnu_cxx::__pool_alloc<T> | <ext/pool_allocator.h> | std::__default_alloc_template<bool,int> | <memory> |
__gnu_cxx::__mt_alloc<T> | <ext/mt_allocator.h> | ||
__gnu_cxx::bitmap_allocator<T> | <ext/bitmap_allocator.h> |
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.
Table B.7. Extension Allocators Continued
Allocator | Include | Version |
---|---|---|
__gnu_cxx::array_allocator<T> | <ext/array_allocator.h> | 4.0.0 |
__gnu_cxx::throw_allocator<T> | <ext/throw_allocator.h> | 4.2.0 |
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.
Removed
<algobase.h>
<algo.h>
<alloc.h>
<bvector.h>
<complex.h>
<defalloc.h>
<deque.h>
<fstream.h>
<function.h>
<hash_map.h>
<hash_set.h>
<hashtable.h>
<heap.h>
<iomanip.h>
<iostream.h>
<istream.h>
<iterator.h>
<list.h>
<map.h>
<multimap.h>
<multiset.h>
<new.h>
<ostream.h>
<pair.h>
<queue.h>
<rope.h>
<set.h>
<slist.h>
<stack.h>
<streambuf.h>
<stream.h>
<tempbuf.h>
<tree.h>
<vector.h>
Added
<hash_map>
and <hash_set>
Added in C++11
<auto_ptr.h>
and <binders.h>
Header dependency streamlining.
<algorithm>
no longer includes <climits>
, <cstring>
, or <iosfwd>
<bitset>
no longer includes <istream>
or <ostream>
, adds <iosfwd>
<functional>
no longer includes <cstddef>
<iomanip>
no longer includes <istream>
, <istream>
, or <functional>
, adds <ioswd>
<numeric>
no longer includes <iterator>
<string>
no longer includes <algorithm>
or <memory>
<valarray>
no longer includes <numeric>
or <cstdlib>
<tr1/hashtable>
no longer includes <memory>
or <functional>
<tr1/memory>
no longer includes <algorithm>
<tr1/random>
no longer includes <algorithm>
or <fstream>
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.
Added.
<atomic>
,
<chrono>
,
<condition_variable>
,
<forward_list>
,
<initializer_list>
,
<mutex>
,
<ratio>
,
<thread>
Updated and improved.
<algorithm>
,
<system_error>
,
<type_traits>
Use of the GNU extension namespace association converted to inline namespaces.
Preliminary support for initializer_list
and defaulted and deleted constructors in container classes.
unique_ptr
.
Support for new character types char16_t
and char32_t added
to char_traits
, basic_string
, numeric_limits
,
and assorted compile-time type traits.
Support for string conversions to_string
and to_wstring
.
Member functions taking string arguments were added to iostreams
including basic_filebuf
, basic_ofstream
,
and basic_ifstream
.
Exception propagation support,
including exception_ptr
, current_exception
, copy_exception
,
and rethrow_exception
.
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.
Added.
<functional>
,
<future>
,
<random>
Updated and improved.
<atomic>
,
<system_error>
,
<type_traits>
Add support for explicit operators and standard layout types.
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 nothrow, 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>
.
Use constexpr and nullptr where appropriate throughout the library.
The library was updated to avoid including
<stddef.h>
in order
to reduce namespace pollution.
Reference-count annotations to assist data race detectors.
Added make_exception_ptr
as an alias of
copy_exception
.
Use of noexcept throughout library.
Partial support for C++11 allocators first appears.
monotonic_clock
renamed to
steady_clock
as required by the final C++11
standard.
A new clocale model for newlib is available.
The library was updated to avoid including
<unistd.h>
in order
to reduce namespace pollution.
Debug Mode was improved for unordered containers.
New random number engines and distributions. Optimisations for random.
New --enable-libstdcxx-verbose configure option
The --enable-libstdcxx-time configure option becomes unnecessary given a sufficiently recent glibc.
Implementation of regex
completed.
C++14 library and TS implementations are added.
copy_exception
deprecated.
__gnu_cxx::array_allocator
deprecated.
ABI transition adds new implementations of several components, using the
abi_tag
attribute and the __cxx11
inline
namespace to distinguish the new entities from the old ones.
Use of the new or old ABI can be selected per-translation unit with the Macros.
New non-reference-counted string
implementation.
New list
implementation containing a new
data member in order to provide O(1) size()
.
New ios_base::failure
implementation inheriting
from system_error
.
C++11 support completed (movable iostreams, new I/O manipulators,
Unicode conversion utilities, atomic operations for
shared_ptr
, functions for notifying condition
variables and making futures ready at thread exit).
Changed formatting of floating point types when
ios_base::fixed|ios_base::scientific
is set in a stream's
format flags.
Improved C++14 support and TS implementations.
New random number engines and distributions.
GDB Xmethods for containers and unique_ptr
added.
has_trivial_default_constructor
,
has_trivial_copy_constructor
and
has_trivial_copy_assign
deprecated.
C++14 support completed.
Support for mathematical special functions (ISO/IEC 29124:2010) added.
Assertions to check function preconditions can be enabled by defining the _GLIBCXX_ASSERTIONS macro. The initial set of assertions are a subset of the checks enabled by the Debug Mode, but without the ABI changes and changes to algorithmic complexity that are caused by enabling the full Debug Mode.
The type of exception thrown by iostreams changed to the cxx11
ABI version of std::ios_base::failure
.
Experimental C++17 support added, including most new library features.
The meaning of shared_ptr<T[]>
changed to
match the C++17 semantics.
Macros added.
has_trivial_default_constructor
,
has_trivial_copy_constructor
and
has_trivial_copy_assign
removed.
Calling a std::bind
result as volatile was deprecated for C++17.
Profile Mode was deprecated.
The exceptions thrown by iostreams can now be caught by handlers for either
version of std::ios_base::failure
.
Improved experimental C++17 support. Headers
<charconv>
and
<filesystem>
.
Experimental implementation of the C++17 Filesystem library added.
Experimental C++2a support
(to_address
and endian
).
AddressSanitizer annotations added to std::vector
to detect out-of-range accesses to the unused capacity of a vector.
std::char_traits<char16_t>::to_int_type(u'\uFFFF')
now returns 0xFFFD
, as 0xFFFF
is
used for std::char_traits<char16_t>::eof()
.
The extension allowing arithmetic on
std::atomic<void*>
and types like
std::atomic<R(*)()>
was deprecated.
The std::uncaught_exception
function was deprecated
for C++17 mode.
The nested typedefs std::hash::result_type and std::hash::argument_type were deprecated for C++17 mode.
The deprecated iostream members ios_base::io_state,
ios_base::open_mode, ios_base::seek_dir, and
basic_streambuf::stossc
were removed for C++17 mode.
The non-standard C++0x std::copy_exception
function
was removed.
For -std=c++11
, -std=c++14
, and
-std=c++17
modes the <complex.h>
header no longer includes the C99 <complex.h>
header.
For the non-default --enable-symvers=gnu-versioned-namespace
configuration, the shared library SONAME has been changed to
libstdc++.so.8
.
C++17 header
<memory_resource>
added.
Experimental C++2a support improved, with new headers
<bit>
and
<version>
added.
Support for new character type char8_t added
to char_traits
, basic_string
,
numeric_limits
,
and relevant locale facets and type traits.
Experimental implementation of the Networking TS library added,
with new headers
<experimental/buffer>
,
<experimental/executor>
,
<experimental/internet>
,
<experimental/io_context>
,
<experimental/net>
,
<experimental/netfwd>
,
<experimental/socket>
,
and
<experimental/timer>
.
Deprecated features removed:
__gnu_cxx::array_allocator
The non-standard std::__is_nullptr_t
type trait
was deprecated.
The std::packaged_task
constructors taking
an allocator argument are only defined for C++11 and C++14.
Several members of std::allocator
were removed
for C++20 mode. The removed functionality has been provided by
std::allocator_traits
since C++11 and that should
be used instead.
The type of the std::iterator
base class of
std::istreambuf_iterator
was changed to be
consistent for all -std
modes.
Before GCC 10.1 the base class had one type in C++98 mode and a
different type in C++11 and later modes. The type in C++98 mode
was changed to be the same as for C++11 and later.
Experimental C++2a support improved, with new headers
<concepts>
,
<ranges>
,
<compare>
,
<coroutine>
,
<numbers>
,
<span>
,
and
<stop_token>
added.
The --enable-cheaders=c_std
configuration
was deprecated.
When compiling as C++20, the operator>>
overloads
for extracting strings into character buffers only work with arrays,
not raw pointers.
std::string::reserve(n)
will no longer reduce
the string's capacity.
Calling reserve()
with no arguments is equivalent
to shrink_to_fit()
, but is deprecated.
shrink_to_fit()
should be used instead.
The std::random_shuffle
algorithms are deprecated
for C++14 and later. The C++11 std::shuffle
algorithm
can be used instead.
The std::unexpected
function and related typedef and
accessors for the unexpected handler are deprecated for C++11 and later.
Dynamic exception specifications should be replaced with noexcept
.
C++98 adaptable function utilities
(std::bind1st
, std::unary_function
,
std::ptr_fun
, std::mem_fun_ref
etc.)
were deprecated for C++11.
std::iterator
, std::raw_storage_iterator
,
get_temporary_buffer
, and std::not_fun
were deprecated for C++17.
Non-standard std::pair
constructors were deprecated.
A non-standard default argument for
vector<bool>::insert(const_iterator, const bool&)
was deprecated.
The bitmap
, mt
, and pool
options for --enable-libstdcxx-allocator
were removed.
For the new
option, std::allocator
no longer derives from __gnu_cxx::new_allocator
;
they both derive from std::__new_allocator
instead.
std::condition_variable::wait
changed to be
noexcept(false)
to allow thread cancellation exceptions to
be thrown from pthread_cond_wait
without aborting
the process.