C++0x Language Support in GCC

C++0x is the working name of the next ISO C++ standard, due by the end of this decade, which introduces a host of new features into the standard C++ language and library. This project seeks to implement new C++0x features in GCC and to make it one of the first compilers to bring C++0x to C++ programmers.

C++0x features are available as part of the "mainline" GCC compiler in the trunk of GCC's Subversion repository and in GCC 4.3 and later. To enable C++0x support, add the command-line parameter -std=c++0x to your g++ command line. Or, to enable GNU extensions in addition to C++0x extensions, add -std=gnu++0x to your g++ command line.

Important: because the ISO C++0x draft is still evolving, GCC's support for C++0x is experimental. No attempt will be made to maintain backward compatibility with implementations of C++0x features that do not reflect the final C++0x standard.

C++0x Language Features in GCC

The following table lists new language features that have been accepted into the C++0x draft standard. The "Proposal" column provides a link to the ISO C++ committee proposal that describes the feature, while the "Available in GCC?" column indicates the first version of GCC that contains an implementation of this feature (if it has been implemented). For the most complete and up-to-date information about new language features in C++0x, please see the ISO C++ Committee Papers and look for the most recent "State of C++ Evolution" paper by Alisdair Meridith.

For information about C++0x support in a specific version of GCC, please see:

Language Feature Proposal Available in GCC?
Rvalue references N2118 GCC 4.3
    Rvalue references for *this N2439 No
Variadic templates N2242 GCC 4.3
    Extending variadic template template parameters N2555 GCC 4.4
Initializer lists N2672 GCC 4.4
Static assertions N1720 GCC 4.3
auto-typed variables N1984 No
    Multi-declarator auto N1737 No
    Removal of auto as a storage-class specifier N2546 GCC 4.4
    New function declarator syntax N2541 No
Lambda expressions and closures N2550 Under development
[Branch]
    Constness of lambda functions N2658 No
Declared type of an expression N2343 GCC 4.3
Right angle brackets N1757 GCC 4.3
Default template arguments for function templates DR226 GCC 4.3
Solving the SFINAE problem for expressions DR339 GCC 4.4
Template aliases N2258 No
Extern templates N1987 Yes
Null pointer constant N2431 No
Strongly-typed enums N2347 GCC 4.4
Generalized constant expressions N2235 No
Alignment support N2341 No
Delegating constructors N1986 No
[Patch]
Inheriting constructors N2540 No
Explicit conversion operators N2437 No
New character types N2249 No
Raw and Unicode string literals N2442 No
Extended PODs N2342 No
Initialization of class objects by rvalues N1610 No
Extended friend declarations N1791 No
Extending sizeof N2253 No
Universal character name literals N2170 No
Defaulted and deleted functions N2346 GCC 4.4
Inline namespaces N2535 GCC 4.4
Unrestricted unions N2544 No
Local and unnamed types as template arguments N2657 No
Minimal support for garbage collection and reachability-based leak detection N2670 No
Concurrency
Sequence points N2239 No
Atomic operations N2427 No
Memory model N2429 No
C++ data-dependency ordering: atomics and memory model N2664 No
Copying and rethrowing exceptions N2179 No
Abandoning a process N2440 No
Allow atomics use in signal handlers N2547 No
Thread-local storage N2659 No
Dynamic initialization and destruction with concurrency N2660 No
C99 Features in C++0x
__func__ predefined identifier N2340 GCC 4.3
C99 preprocessor N1653 GCC 4.3
long long N1811 GCC 4.3
Extended integral types N1988 No
Likely C++0x Features
Concepts N2421 Under development
[Branch]

Ongoing C++0x Development in GCC

C++0x Concepts Branch

Support for the Concepts feature, which is a likely candidate for inclusion in C++0x, is under development on a separate development branch, branches/cxx0x-concepts-branch in the GCC Subversion repository. This branch is maintained by Douglas Gregor <doug.gregor@gmail.com> and Jason Merrill <jason@redhat.com>.

Status
At present, the concepts branch provides almost no support for concepts. We are in the process of migrating code from the prototype ConceptGCC.
Commit policy
This branch is limited to support for C++0x concepts. Other C++0x features should be completed elsewhere and submitted for inclusion in mainline GCC. Guidelines for committing changes to this branch:

C++0x Lambda Functions Branch

Support for lambda functions, which is in the working draft of C++0x, is under development in a separate branch, branches/cxx0x-lambdas-branch, in the GCC Subversion repository. This branch is maintained by John Freeman <jfreeman08@gmail.com>.

Status
The branch is freshly created and the migration of an existing partial implementation has only just begun.

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