Chapter 1. Status
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## Chapter 1. Status

## Implementation Status

### C++ 1998/2003

#### Implementation Status

This status table is based on the table of contents of ISO/IEC 14882:2003.

This page describes the C++ support in mainline GCC SVN, not in any particular release.

Table 1.1. C++ 1998/2003 Implementation Status

Section | Description | Status | Comments
--- | --- | --- | ---
18 | Language support
18.1 | Types | Y |
18.2 | Implementation properties | Y |
18.2.1 | Numeric Limits |  |
18.2.1.1 | Class template `numeric_limits` | Y |
18.2.1.2 | `numeric_limits` members | Y |
18.2.1.3 | `float_round_style` | Y |
18.2.1.4 | `float_denorm_style` | Y |
18.2.1.5 | `numeric_limits` specializations | Y |
18.2.2 | C Library | Y |
18.3 | Start and termination | Y |
18.4 | Dynamic memory management | Y |
18.5 | Type identification |  |
18.5.1 | Class type_info | Y |
18.5.2 | Class bad_cast | Y |
18.5.3 | Class bad_typeid | Y |
18.6 | Exception handling |  |
18.6.1 | Class exception | Y |
18.6.2 | Violation exception-specifications | Y |
18.6.3 | Abnormal termination | Y |
18.6.4 | `uncaught_exception` | Y |
18.7 | Other runtime support | Y |
19 | Diagnostics
19.1 | Exception classes | Y |
19.2 | Assertions | Y |
19.3 | Error numbers | Y |
20 | General utilities
20.1 | Requirements | Y |
20.2 | Utility components |  |
20.2.1 | Operators | Y |
20.2.2 | `pair` | Y |
20.3 | Function objects |  |
20.3.1 | Base | Y |
20.3.2 | Arithmetic operation | Y |
20.3.3 | Comparisons | Y |
20.3.4 | Logical operations | Y |
20.3.5 | Negators | Y |
20.3.6 | Binders | Y |
20.3.7 | Adaptors for pointers to functions | Y |
20.3.8 | Adaptors for pointers to members | Y |
20.4 | Memory |  |
20.4.1 | The default allocator | Y |
20.4.2 | Raw storage iterator | Y |
20.4.3 | Temporary buffers | Y |
20.4.4 | Specialized algorithms | Y |
20.4.4.1 | `uninitialized_copy` | Y |
20.4.4.2 | `uninitialized_fill` | Y |
20.4.4.3 | `uninitialized_fill_n` | Y |
20.4.5 | Class template `auto_ptr` | Y |
20.4.6 | C library | Y |
21 | Strings
21.1 | Character traits |  |
21.1.1 | Character traits requirements | Y |
21.1.2 | traits typedef | Y |
21.1.3 | `char_traits` specializations |  |
21.1.3.1 | struct `char_traits<char>` | Y |
21.1.3.2 | struct `char_traits<wchar_t>` | Y |
21.2 | String classes | Y |
21.3 | Class template `basic_string` | Y |
21.4 | Null-terminated sequence utilities | Y | C library dependency
22 | Localization
22.1 | Locales |  |
22.1.1 | Class `locale` | Y |
22.1.2 | `locale` globals | Y |
22.1.3 | Convenience interfaces |  |
22.1.3.1 | Character classification | Y |
22.1.3.2 | Character conversions | Y |
22.2 | Standard locale categories |  |
22.2.1 | `ctype` | Y |
22.2.2 | Numeric |  |
22.2.2.1 | `num_get` | Y |
22.2.2.2 | `num_put` | Y |
22.2.3 | `num_punct` | Y |
22.2.4 | `collate` | Y |
22.2.5 | Time |  |
22.2.5.1 | `time_get` | Y |
22.2.5.2 | `time_get_byname` | Y |
22.2.5.3 | `time_put` | Y |
22.2.5.3 | `time_put_byname` | Y |
22.2.6 | Monetary |  |
22.2.6.1 | `money_get` | Y |
22.2.6.2 | `money_put` | Y |
22.2.6.3 | `money_punct` | Y |
22.2.6.4 | `money_punct_byname` | Y |
22.2.7 | `messages` | Y |
22.2.8 | Program-defined facets | Y |
22.3 | C Library Locales | Y |
23 | Containers
23.1 | Container requirements | Y |
23.2 | Sequence containers |  |
23.2.1 | Class template `deque` | Y |
23.2.2 | Class template `list` | Y |
23.2.3 | Adaptors |  |
23.2.3.1 | Class template `queue` | Y |
23.2.3.2 | Class template `priority_queue` | Y |
23.2.3.3 | Class template `stack` | Y |
23.2.4 | Class template `vector` | Y |
23.2.5 | Class `vector<bool>` | Y |
23.3 | Associative containers |  |
23.3.1 | Class template `map` | Y |
23.3.2 | Class template `multimap` | Y |
23.3.3 | Class template `set` | Y |
23.3.4 | Class template `multiset` | Y |
24 | Iterators
24.1 | Requirements | Y |
24.2 | Header `<iterator>` synopsis | Y |
24.3 | Iterator primitives | Y |
24.4 | Predefined iterators and Iterator adaptors |  |
24.4.1 | Reverse iterators | Y |
24.4.2 | Insert iterators | Y |
24.5 | Stream iterators |  |
24.5.1 | Class template `istream_iterator` | Y |
24.5.2 | Class template `ostream_iterator` | Y |
24.5.3 | Class template `istreambuf_iterator` | Y |
24.5.4 | Class template `ostreambuf_iterator` | Y |
25 | Algorithms
25.1 | Non-modifying sequence operations | Y |
25.2 | Mutating sequence operations | Y |
25.3 | Sorting and related operations | Y |
25.4 | C library algorithms | Y |
26 | Numerics
26.1 | Numeric type requirements | Y |
26.2 | Complex numbers | Y |
26.3 | Numeric arrays |  |
26.3.1 | Header `<valarray>` synopsis | Y |
26.3.2 | Class template `valarray` | Y |
26.3.3 | `valarray` non-member operations | Y |
26.3.4 | Class `slice` | Y |
26.3.5 | Class template `slice_array` | Y |
26.3.6 | Class `gslice` | Y |
26.3.7 | Class template `gslice_array` | Y |
26.3.8 | Class template `mask_array` | Y |
26.3.9 | Class template `indirect_array` | Y |
26.4 | Generalized numeric operations |  |
26.4.1 | `accumulate` | Y |
26.4.2 | `inner_product` | Y |
26.4.3 | `partial_sum` | Y |
26.4.4 | `adjacent_difference` | Y |
26.4.5 | iota | Y |
26.5 | C Library | Y |
27 | Input/output
27.1 | Requirements | Y |
27.2 | Forward declarations | Y |
27.3 | Standard iostream objects | Y |
27.3.1 | Narrow stream objects | Y |
27.3.2 | Wide stream objects | Y |
27.4 | Iostreams base classes | Y |
27.5 | Stream buffers | Y |
27.6 | Formatting and manipulators | Y |
27.7 | String-based streams | Y |
27.8 | File-based streams | Y |
Appendix D | Compatibility features
D.1 | Increment operator with bool operand |  |
D.2 | `static` keyword |  |
D.3 | Access declarations |  |
D.4 | Implicit conversion from const strings |  |
D.5 | C standard library headers |  |
D.6 | Old iostreams members |  |
D.7 | char* streams |  |

#### Implementation Specific Behavior

The ISO standard defines the following phrase:

> `[1.3.5] implementation-defined behavior`

>   Behavior, for a well-formed program construct and correct data, that depends on the implementation and that each implementation shall document.

We do so here, for the C++ library only. Behavior of the compiler, linker, runtime loader, and other elements of "the implementation" are documented elsewhere. Everything listed in Annex B, Implementation Qualities, are also part of the compiler, not the library.

For each entry, we give the section number of the standard, when applicable. This list is probably incomplet and inkorrekt.

[1.9]/11 #3 If `isatty(3)` is true, then interactive stream support is implied.

[17.4.4.5] Non-reentrant functions are probably best discussed in the various sections on multithreading (see above).

[18.1]/4 The type of `NULL` is described under Support.

[18.3]/8 Even though it's listed in the library sections, libstdc++ has zero control over what the cleanup code hands back to the runtime loader. Talk to the compiler people. :-)

[18.4.2.1]/5 (bad_alloc), [18.5.2]/5 (bad_cast), [18.5.3]/5 (bad_typeid), [18.6.1]/8 (exception), [18.6.2.1]/5 (bad_exception): The `what()` member function of class `std::exception`, and these other classes publicly derived from it, returns the name of the class, e.g. `"std::bad_alloc"`.

[18.5.1]/7 The return value of `std::type_info::name()` is the mangled type name. You will need to call `c++filt` and pass the names as command-line parameters to demangle them, or call a runtime demangler function.

[20.1.5]/5 "Implementors are encouraged to supply libraries that can accept allocators that encapsulate more general memory models and that support non-equal instances. In such implementations, any requirements imposed on allocators by containers beyond those requirements that appear in Table 32, and the semantics of containers and algorithms when allocator instances compare non-equal, are implementation-defined." There is experimental support for non-equal allocators in the standard containers in C++98 mode. There are no additional requirements on allocators. It is undefined behaviour to swap two containers if their allocators are not equal.

[21.1.3.1]/3,4, [21.1.3.2]/2, [21.3]/6 basic_string::iterator, basic_string::const_iterator, [23.*]'s foo::iterator, [27.*]'s foo::*_type, others... Nope, these types are called implementation-defined because you shouldn't be taking advantage of their underlying types. Listing them here would defeat the purpose. :-)

[21.1.3.1]/5 I don't really know about the mbstate_t stuff... see the `codecvt` notes for what does exist.

[22.*] Anything and everything we have on locale implementation will be described under Localization.

[26.2.8]/9 I have no idea what `complex<T>`'s `pow(0,0)` returns.

[27.4.2.4]/2 Calling `std::ios_base::sync_with_stdio` after I/O has already been performed on the standard stream objects will flush the buffers, and destroy and recreate the underlying buffer instances. Whether or not the previously-written I/O is destroyed in this process depends mostly on the `--enable-libio` choice: for stdio, if the written data is already in the stdio buffer, the data may be completely safe!

[27.6.1.1.2], [27.6.2.3] The I/O sentry ctor and dtor can perform additional work than the minimum required. We are not currently taking advantage of this yet.

[27.7.1.3]/16, [27.8.1.4]/10 The effects of `pubsetbuf/setbuf` are described in the Input and Output chapter.

[27.8.1.4]/16 Calling `fstream::sync` when a get area exists will... whatever `fflush()` does, I think.

### C++ 2011

This table is based on the table of contents of ISO/IEC JTC1 SC22 WG21 Doc No: N3290 Date: 2011-04-11 Final Draft International Standard, Standard for Programming Language C++

In this implementation the `-std=gnu++11` or `-std=c++11` flag must be used to enable language and library features. See dialect options. The pre-defined symbol `__cplusplus` is used to check for the presence of the required flag.

This page describes the C++11 support in mainline GCC SVN, not in any particular release.

Table 1.2. C++ 2011 Implementation Status

Section | Description | Status | Comments
--- | --- | --- | ---
18 | Language support
18.1 | General | Y |
18.2 | Types | Y |
18.3 | Implementation properties |  |
18.3.2 | Numeric Limits |  |
18.3.2.3 | Class template `numeric_limits` | Y |
18.3.2.4 | `numeric_limits` members | Y |
18.3.2.5 | `float_round_style` | N |
18.3.2.6 | `float_denorm_style` | N |
18.3.2.7 | `numeric_limits` specializations | Y |
18.3.3 | C Library | Y |
18.4 | Integer types |  |
18.4.1 | Header `<cstdint>` synopsis | Y |
18.5 | Start and termination | Partial | C library dependency for quick_exit, at_quick_exit
18.6 | Dynamic memory management | Y |
18.7 | Type identification |  |
18.7.1 | Class type_info | Y |
18.7.2 | Class bad_cast | Y |
18.7.3 | Class bad_typeid | Y |
18.8 | Exception handling |  |
18.8.1 | Class exception | Y |
18.8.2 | Class bad_exception | Y |
18.8.3 | Abnormal termination | Y |
18.8.4 | `uncaught_exception` | Y |
18.8.5 | Exception Propagation | Y |
18.8.6 | `nested_exception` | Y |
18.9 | Initializer lists |  |
18.9.1 | Initializer list constructors | Y |
18.9.2 | Initializer list access | Y |
18.9.3 | Initializer list range access | Y |
18.10 | Other runtime support | Y |
19 | Diagnostics
19.1 | General | Y |
19.2 | Exception classes | Y |
19.3 | Assertions | Y |
19.4 | Error numbers | Y |
19.5 | System error support |  |
19.5.1 | Class `error_category` | Y |
19.5.2 | Class `error_code` | Y |
19.5.3 | Class `error_condition` | Y |
19.5.4 | Comparison operators | Y |
19.5.5 | Class `system_error` | Y |
20 | General utilities
20.1 | General |  |
20.2 | Utility components |  |
20.2.1 | Operators | Y |
20.2.2 | Swap | Y |
20.2.3 | `forward` and `move` helpers | Y |
20.2.4 | Function template `declval` | Y |
20.3 | Pairs |  |
20.3.1 | In general |  |
20.3.2 | Class template `pair` | Y |
20.3.3 | Specialized algorithms | Y |
20.3.4 | Tuple-like access to `pair` | Y |
20.3.5 | Piecewise construction | Y |
20.4 | Tuples |  |
20.4.1 | In general |  |
20.4.2 | Class template `tuple` |  |
20.4.2.1 | Construction | Y |
20.4.2.2 | Assignment | Y |
20.4.2.3 | Swap | Y |
20.4.2.4 | Tuple creation functions | Y |
20.4.2.5 | Tuple helper classes | Y |
20.4.2.6 | Element access | Y |
20.4.2.7 | Relational operators | Y |
20.4.2.8 | Tuple traits | Y |
20.4.2.9 | Tuple specialized algorithms | Y |
20.5 | Class template `bitset` | Y |
20.5.1 | `bitset` constructors | Y |
20.5.2 | `bitset` members | Y |
20.5.3 | `bitset` hash support | Y |
20.5.4 | `bitset` operators | Y |
20.6 | Memory |  |
20.6.1 | In general |  |
20.6.2 | Header `<memory>` synopsis |  |
20.6.3 | Pointer traits | Y |
20.6.4 | Pointer safety | Y |
20.6.5 | Align | Y |
20.6.6 | Allocator argument tag | Y |
20.6.7 | `uses_allocator` | Y |
20.6.8 | Allocator traits | Y |
20.6.9 | The default allocator | Y |
20.6.10 | Raw storage iterator | Y |
20.6.11 | Temporary buffers | Y |
20.6.12 | Specialized algorithms |  |
20.6.12.1 | `addressof` | Y |
20.6.12.2 | `uninitialized_copy` | Y |
20.6.12.3 | `uninitialized_fill` | Y |
20.6.12.4 | `uninitialized_fill_n` | Y |
20.6.13 | C library | Y |
20.7 | Smart pointers |  |
20.7.1 | Class template `unique_ptr` | Y |
20.7.2 | Shared-ownership pointers | Y |
20.7.2.1 | Class `bad_weak_ptr` | Y |
20.7.2.2 | Class template `shared_ptr` | Y | Uses code from boost::shared_ptr.
20.7.2.3 | Class template `weak_ptr` | Y |
20.7.2.4 | Class template `emable_shared_from_this` | Y |
20.7.2.5 | `shared_ptr` atomic access | Y |
20.7.2.6 | Smart pointer hash support | Y |
20.8 | Function objects |  |
20.8.1 | Definitions |  |
20.8.2 | Requirements |  |
20.8.3 | Class template `reference_wrapper` | Y |
20.8.4 | Arithmetic operation | Y |
20.8.5 | Comparisons | Y |
20.8.6 | Logical operations | Y |
20.8.7 | Bitwise operations | Y |
20.8.8 | Negators | Y |
20.8.9 | Function template `bind` | Y |
20.8.10 | Function template `mem_fn` | Y |
20.8.11 | Polymorphic function wrappers |  |
20.8.11.1 | Class `bad_function_call` | Y |
20.8.11.2 | Class template `function` | Partial | Missing allocator support
20.8.12 | Class template `hash` | Y |
20.9 | Metaprogramming and type traits |  |
20.9.1 | Requirements | Y |
20.9.2 | Header `<type_traits>` synopsis |  |
20.9.3 | Helper classes | Y |
20.9.4 | Unary Type Traits | Y |
20.9.4.1 | Primary type categories | Y |
20.9.4.2 | Composite type traits | Y |
20.9.4.3 | Type properties | Y |
20.9.5 | Type property queries | Y |
20.9.6 | Relationships between types | Y |
20.9.7 | Transformations between types |  |
20.9.7.1 | Const-volatile modifications | Y |
20.9.7.2 | Reference modifications | Y |
20.9.7.3 | Sign modifications | Y |
20.9.7.4 | Array modifications | Y |
20.9.7.5 | Pointer modifications | Y |
20.9.7.6 | Other transformations | Y |
20.10 | Compile-time rational arithmetic |  |
20.10.1 | In general |  |
20.10.2 | Header `<ratio>` synopsis |  |
20.10.3 | Class template `ratio` | Y |
20.10.4 | Arithmetic on `ratio`s | Y |
20.10.5 | Comparison of `ratio`s | Y |
20.10.6 | SI types for `ratio` | Y |
20.11 | Time utilities |  |
20.11.3 | Clock requirements | Y |
20.11.4 | Time-related traits |  |
20.11.4.1 | `treat_as_floating_point` | Y |
20.11.4.2 | `duration_values` | Y |
20.11.4.3 | Specializations of `common_type` | Y |
20.11.5 | Class template `duration` | Y |
20.11.6 | Class template `time_point` | Y |
20.11.7 | Clocks |  |
20.11.7.1 | Class `system_clock` | Y |
20.11.7.2 | Class `steady_clock` | Y |
20.11.7.3 | Class `high_resolution_clock` | Y |
20.11.8 | Date and time functions | Y |
20.12 | Scoped allocator adaptor | Y |
20.12.1 | Header `<scoped_allocator>` synopsis |  |
20.12.2 | Scoped allocator adaptor member types | Y |
20.12.3 | Scoped allocator adaptor constructors | Y |
20.12.4 | Scoped allocator adaptor members | Y |
20.12.5 | Scoped allocator operators | Y |
20.13 | Class `type_index` | Y |
21 | Strings
21.1 | General | Y |
21.2 | Character traits |  |
21.2.1 | Character traits requirements | Y |
21.2.2 | traits typedefs | Y |
21.2.3 | `char_traits` specializations |  |
21.2.3.1 | struct `char_traits<char>` | Y |
21.2.3.2 | struct `char_traits<char16_t>` | Y |
21.2.3.3 | struct `char_traits<char32_t>` | Y |
21.2.3.4 | struct `char_traits<wchar_t>` | Y |
21.3 | String classes | Y |
21.4 | Class template `basic_string` | Y |
21.5 | Numeric Conversions | Y |
21.6 | Hash support | Y |
21.7 | Null-terminated sequence utilities | Partial | C library dependency. Missing `<cuchar>`
22 | Localization
22.1 | General | Y |
22.2 | Header `<locale>` synopsis | Y |
22.3 | Locales |  |
22.3.1 | Class `locale` | Y |
22.3.2 | `locale` globals | Y |
22.3.3 | Convenience interfaces |  |
22.3.3.1 | Character classification | Y |
22.3.3.2 | Conversions |  |
22.3.3.2.1 | Character conversions | Y |
22.3.3.2.2 | `string` conversions | Y |
22.3.3.2.3 | Buffer conversions | Y |
22.4 | Standard `locale` categories |  |
22.4.1 | The `ctype` category | Y |
22.4.2 | The numeric category |  |
22.4.2.1 | `num_get` | Y |
22.4.2.2 | `num_put` | Y |
22.4.3 | The numeric punctuation facet | Y |
22.4.4 | The collate category | Y |
22.4.5 | The time category |  |
22.4.5.1 | Class template `time_get` | Y |
22.4.5.2 | Class template `time_get_byname` | Y |
22.4.5.3 | Class template `time_put` | Y |
22.4.5.3 | Class template `time_put_byname` | Y |
22.4.6 | The monetary category |  |
22.4.6.1 | Class template `money_get` | Y |
22.4.6.2 | Class template `money_put` | Y |
22.4.6.3 | Class template `money_punct` | Y |
22.4.6.4 | Class template `money_punct_byname` | Y |
22.4.7 | The message retrieval category | Y |
22.4.8 | Program-defined facets | Y |
22.5 | Standard code conversion facets | Y |
22.6 | C Library Locales | Y |
23 | Containers
23.1 | General |  |
23.2 | Container requirements |  |
23.2.1 | General container requirements | Y |
23.2.2 | Container data races | Y |
23.2.3 | Sequence containers | Y |
23.2.4 | Associative containers | Y |
23.2.5 | Unordered associative containers | Y |
23.3 | Sequence containers |  |
23.3.2 | Class template `array` | Y |
23.3.3 | Class template `deque` | Y |
23.3.4 | Class template `forward_list` | Y |
23.3.5 | Class template `list` | Y |
23.3.6 | Class template `vector` | Y |
23.3.7 | Class `vector<bool>` | Y |
23.4 | Associative containers |  |
23.4.4 | Class template `map` | Y |
23.4.5 | Class template `multimap` | Y |
23.4.6 | Class template `set` | Y |
23.4.7 | Class template `multiset` | Y |
23.5 | Unordered associative containers |  |
23.5.4 | Class template `unordered_map` | Y |
23.5.5 | Class template `unordered_multimap` | Y |
23.5.6 | Class template `unordered_set` | Y |
23.5.7 | Class template `unordered_multiset` | Y |
23.6 | Container adaptors |  |
23.6.1 | Class template `queue` | Y |
23.6.2 | Class template `priority_queue` | Y |
23.6.3 | Class template `stack` | Y |
24 | Iterators
24.1 | General | Y |
24.2 | Iterator requirements | Y |
24.3 | Header `<iterator>` synopsis | Y |
24.4 | Iterator primitives | Y |
24.5 | Iterator adaptors |  |
24.5.1 | Reverse iterators | Y |
24.5.2 | Insert iterators | Y |
24.5.3 | Move iterators | Y |
24.6 | Stream iterators |  |
24.6.1 | Class template `istream_iterator` | Y |
24.6.2 | Class template `ostream_iterator` | Y |
24.6.3 | Class template `istreambuf_iterator` | Y |
24.6.4 | Class template `ostreambuf_iterator` | Y |
24.6.5 | range access | Y |
25 | Algorithms
25.1 | General |  |
25.2 | Non-modifying sequence operations | Y |
25.3 | Mutating sequence operations | Y |
25.4 | Sorting and related operations | Y |
25.5 | C library algorithms | Y |
26 | Numerics
26.1 | General | Y |
26.2 | Numeric type requirements | Y |
26.3 | The floating-point environment | Y |
26.4 | Complex numbers | Y |
26.5 | Random number generation |  |
26.5.1 | Requirements |  |
26.5.2 | Header `<random>` synopsis |  |
26.5.3 | Random number engine class templates |  |
26.5.3.1 | Class template `linear_congruential_engine` | Y |
26.5.3.2 | Class template `mersenne_twister_engine` | Y |
26.5.3.3 | Class template `subtract_with_carry_engine` | Y |
26.5.4 | Random number engine adaptor class templates |  |
26.5.4.2 | Class template `discard_block_engine` | Y |
26.5.4.3 | Class template `independent_bits_engine` | Y |
26.5.4.4 | Class template `shuffle_order_engine` | Y |
26.5.5 | Engines and engine adaptors with predefined parameters | Y |
26.5.6 | Class `random_device` | Y |
26.5.7 | Utilities |  |
26.5.7.1 | Class `seed_seq` | Y |
26.5.7.2 | Function template `generate_canonical` | Y |
26.5.8 | Random number distribution class templates |  |
26.5.8.2 | Uniform distributions |  |
26.5.8.2.1 | Class template `uniform_int_distribution` | Y |
26.5.8.2.2 | Class template `uniform_real_distribution` | Y |
26.5.8.3 | Bernoulli distributions |  |
26.5.8.3.1 | Class `bernoulli_distribution` | Y |
26.5.8.3.2 | Class template `binomial_distribution` | Y |
26.5.8.3.3 | Class template `geometric_distribution` | Y |
26.5.8.3.4 | Class template `negative_binomial_distribution` | Y |
26.5.8.4 | Poisson distributions |  |
26.5.8.4.1 | Class template `poisson_distribution` | Y |
26.5.8.4.2 | Class template `exponential_distribution` | Y |
26.5.8.4.3 | Class template `gamma_distribution` | Y |
26.5.8.4.4 | Class template `weibull_distribution` | Y |
26.5.8.4.5 | Class template `extreme_value_distribution` | Y |
26.5.8.5 | Normal distributions |  |
26.5.8.5.1 | Class template `normal_distribution` | Y |
26.5.8.5.2 | Class template `lognormal_distribution` | Y |
26.5.8.5.3 | Class template `chi_squared_distribution` | Y |
26.5.8.5.4 | Class template `cauchy_distribution` | Y |
26.5.8.5.5 | Class template `fisher_f_distribution` | Y |
26.5.8.5.6 | Class template `student_t_distribution` | Y |
26.5.8.6 | Sampling distributions |  |
26.5.8.6.1 | Class template `discrete_distribution` | Y |
26.5.8.6.2 | Class template `piecewise_constant_distribution` | Y |
26.5.8.6.3 | Class template `piecewise_linear_distribution` | Y |
26.6 | Numeric arrays |  |
26.6.1 | Header `<valarray>` synopsis | Y |
26.6.2 | Class template `valarray` | Y |
26.6.3 | `valarray` non-member operations | Y |
26.6.4 | Class `slice` | Y |
26.6.5 | Class template `slice_array` | Y |
26.6.6 | The `gslice` class | Y |
26.6.7 | Class template `gslice_array` | Y |
26.6.8 | Class template `mask_array` | Y |
26.6.9 | Class template `indirect_array` | Y |
26.6.10 | `valarray` range access | Y |
26.7 | Generalized numeric operations |  |
26.7.1 | Header `<numeric>` synopsis | Y |
26.7.2 | `accumulate` | Y |
26.7.3 | `inner_product` | Y |
26.7.4 | `partial_sum` | Y |
26.7.5 | `adjacent_difference` | Y |
26.7.6 | iota | Y |
26.8 | C Library | Y |
27 | Input/output library
27.1 | General | Y |
27.2 | Iostreams requirements | Y |
27.2.1 | Imbue Limitations | Y |
27.2.2 | Positioning Type Limitations | Y |
27.2.3 | Thread safety | Partial |
27.3 | Forward declarations | Y |
27.4 | Standard iostream objects | Y |
27.4.1 | Overview | Y |
27.4.2 | Narrow stream objects | Y |
27.4.3 | Wide stream objects | Y |
27.5 | Iostreams base classes | Y |
27.6 | Stream buffers | Y |
27.7 | Formatting and manipulators | Y |
27.8 | String-based streams | Y |
27.9 | File-based streams | Y |
28 | Regular expressions
28.1 | General | Y |
28.2 | Definitions | Y |
28.3 | Requirements | Y |
28.4 | Header `<regex>` synopsis | Y |
28.5 | Namespace `std::regex_constants` | Y |
28.6 | Class `regex_error` | Y |
28.7 | Class template `regex_traits` | Partial | `transform_primary` is not correctly implemented |
28.8 | Class template `basic_regex` | Y |
28.9 | Class template `sub_match` | Y |
28.10 | Class template `match_results` | Y |
28.11 | Regular expression algorithms | Y |
28.12 | Regular expression Iterators | Y |
28.13 | Modified ECMAScript regular expression grammar | Y |
29 | Atomic operations
29.1 | General | Y |
29.2 | Header `<atomic>` synopsis | Y |
29.3 | Order and consistency | Partial |
29.4 | Lock-free property | Y |
29.5 | Atomic types | Y |
29.6 | Operations on atomic types | Y |
29.7 | Flag Type and operations | Y |
29.8 | Fences | Y |
30 | Thread support
30.1 | General | Y |
30.2 | Requirements | Y |
30.3 | Threads |  |
30.3.1 | Class `thread` | Partial | `thread::id` comparisons not well-defined
30.3.2 | Namespace `this_thread` | Y |
30.4 | Mutual exclusion |  |
30.4.1 | Mutex requirements |  |
30.4.1.1 | In general |  |
30.4.1.2 | Mutex types |  |
30.4.1.2.1 | Class `mutex` | Y |
30.4.1.2.2 | Class `recursive_mutex` | Y |
30.4.1.3 | Timed mutex types |  |
30.4.1.3.1 | Class `timed_mutex` | Y |
30.4.1.3.2 | Class `recursive_timed_mutex` | Y |
30.4.2 | Locks |  |
30.4.2.1 | Class template `lock_guard` | Y |
30.4.2.2 | Class template `unique_lock` | Y |
30.4.3 | Generic locking algorithms | Y |
30.4.4 | Call once |  |
30.4.4.1 | Struct `once_flag` | Y |
30.4.4.2 | Function `call_once` | Y |
30.5 | Condition variables | Y |
30.5.1 | Class `condition_variable` | Y |
30.5.2 | Class `condition_variable_any` | Y |
30.6 | Futures |  |
30.6.1 | Overview |  |
30.6.2 | Error handling | Y |
30.6.3 | Class `future_error` | Y |
30.6.4 | Shared state | Y |
30.6.5 | Class template `promise` | Y |
30.6.6 | Class template `future` | Y |
30.6.7 | Class template `shared_future` | Y |
30.6.8 | Function template `async` | Y |
30.6.9 | Class template `packaged_task` | Y |
Appendix D | Compatibility features
D.1 | Increment operator with `bool` operand |  |
D.2 | `register` keyword |  |
D.3 | Implicit declaration of copy functions |  |
D.4 | Dynamic exception specifications |  |
D.5 | C standard library headers |  |
D.6 | Old iostreams members |  |
D.7 | `char*` streams |  |
D.8 | Function objects |  |
D.9 | Binders |  |
D.10 | `auto_ptr` |  |
D.11 | Violating exception-specifications |  |

#### Implementation Specific Behavior

For behaviour which is also specified by the 1998 and 2003 standards, see C++ 1998/2003 Implementation Specific Behavior. This section only documents behaviour which is new in the 2011 standard.

17.6.5.12 [res.on.exception.handling] There are no implementation-defined exception classes, only standard exception classes (or classes derived from them) will be thrown.

17.6.5.14 [value.error.codes] The `error_category` for errors originating outside the OS, and the possible error code values for each error category, should be documented here.

18.6.2.2 [new.badlength] `what()` returns `"std::bad_array_new_length"`.

20.6.9.1 [allocator.member]/5 Over-aligned types are not supported by `std::allocator`.

20.7.2.2.1 [util.smartptr.shared.const] When a `shared_ptr` constructor fails `bad_alloc` (or types derived from it) will be thrown, or when an allocator is passed to the constructor then any exceptions thrown by the allocator.

20.7.2.0 [util.smartptr.weakptr] `what()` returns `"bad_weak_ptr"`.

20.8.9.1.3 [func.bind.place]/1 There are 29 placeholders defined and the placeholder types are `CopyAssignable`.

20.11.7.1 [time.clock.system]/3, /4 Time point values are truncated to `time_t` values. There is no loss of precision for conversions in the other direction.

20.15.7 [meta.trans]/2 `aligned_storage` does not support extended alignment.

21.2.3.2 [char.traits.specializations.char16_t], 21.2.3.3 [char.traits.specializations.char32_t] The types `u16streampos` and `u32streampos` are both synonyms for `fpos<mbstate_t>`. The function `eof` returns `int_type(-1)`. `char_traits<char16_t>::to_int_type` will transform the "noncharacter" U+FFFF to U+FFFD (REPLACEMENT CHARACTER). This is done to ensure that `to_int_type` never returns the same value as `eof`, which is U+FFFF.

22.3.1 [locale] There is one global locale for the whole program, not per-thread.

22.4.5.1.2 [locale.time.get.virtuals], 22.4.5.3.2 [locale.time.put.virtuals] Additional supported formats should be documented here.

22.4.7.1.2 [locale.messages.virtuals] The mapping should be documented here.

23.3.2.1 [array.overview] `array<T, N>::iterator` is `T*` and `array<T, N>::const_iterator` is `const T*`.

23.5.4.2 [unord.map.cnstr], 23.5.5.2 [unord.multimap.cnstr], 23.5.6.2 [unord.set.cnstr], 23.5.7.2 [unord.multiset.cnstr] The default minimal bucket count is 0 for the default constructors, range constructors and initializer-list constructors.

25.3.12 [alg.random.shuffle] The two-argument overload of `random_shuffle` uses `rand` as the source of randomness.

26.5.5 [rand.predef] The type `default_random_engine` is a synonym for `minstd_rand0`.

26.5.6 [rand.device] The default `token` argument to the `random_device` constructor is `"default"`. Other valid arguments are `"/dev/random"` and `"/dev/urandom"`, which determine the character special file to read random bytes from. The `"default"` token will read bytes from a hardware RNG if available (currently this only supports the IA-32 RDRAND instruction) otherwise it is equivalent to `"/dev/urandom"`. An exception of type `runtime_error` will be thrown if a `random_device` object cannot open or read from the source of random bytes.

26.5.8.1 [rand.dist.general] The algorithms used by the distributions should be documented here.

26.8 [c.math] Whether the `rand` function introduces data races depends on the C library as the function is not provided by libstdc++.

27.8.2.1 [stringbuf.cons] Whether the sequence pointers are copied by the `basic_stringbuf` move constructor should be documented here.

27.9.1.2 [filebuf.cons] Whether the sequence pointers are copied by the `basic_filebuf` move constructor should be documented here.

28.5.1 [re.synopt], 28.5.2 [re.matchflag] , 28.5.3 [re.err] `syntax_option_type`, `match_flag_type` and `error_type` are unscoped enumeration types.

28.7 [re.traits] The `blank` character class corresponds to the `ctype_base::blank` mask.

29.4 [atomics.lockfree] The values of the `ATOMIC_xxx_LOCK_FREE` macros depend on the target and cannot be listed here.

30.2.3 [thread.req.native]/1 `native_handle_type` and `native_handle` are provided. The handle types are defined in terms of the Gthreads abstraction layer, although this is subject to change at any time. Any use of `native_handle` is inherently non-portable and not guaranteed to work between major releases of GCC.

- `thread`: The native handle type is a typedef for `__gthread_t` i.e. `pthread_t` when GCC is configured with the `posix` thread model. The value of the native handle is undefined for a thread which is not joinable.

- `mutex` and `timed_mutex`: The native handle type is `__gthread_mutex_t*` i.e. `pthread_mutex_t*` for the `posix` thread model.

- `recursive_mutex` and `recursive_timed_mutex`: The native handle type is `__gthread_recursive_mutex_t*` i.e. `pthread_mutex_t*` for the `posix` thread model.

- `condition_variable`: The native handle type is `__gthread_cond_t*` i.e. `pthread_cond_t*` for the `posix` thread model.

30.6.1 [futures.overview]/2 `launch` is a scoped enumeration type with overloaded operators to support bitmask operations. There are no additional bitmask elements defined.

### C++ 2014

In this implementation the `-std=gnu++14` or `-std=c++14` flag must be used to enable language and library features. See dialect options. The pre-defined symbol `__cplusplus` is used to check for the presence of the required flag.

This page describes the C++14 and library TS support in mainline GCC SVN, not in any particular release.

Table 1.3. C++ 2014 Implementation Status

Paper | Title | Status | Comments
--- | --- | --- | ---
N3669 | Fixing constexpr member functions without const | Y |
N3668 | `exchange()` utility function | Y |
N3670 | Wording for Addressing Tuples by Type | Y |
N3656 | `make_unique` | Y |
N3462 | `std::result_of` and SFINAE | Y |
N3545 | An Incremental Improvement to `integral_constant` | Y |
N3642 | User-defined Literals for Standard Library Types | Y |
N3671 | Making non-modifying sequence operations more robust | Y |
N3654 | Quoted Strings Library Proposal | Y |
N3469 | Constexpr Library Additions: chrono | Y |
N3470 | Constexpr Library Additions: containers | Y |
N3471 | Constexpr Library Additions: utilities | Y |
N3658 | Compile-time integer sequences | Y |
N3659 | Shared Locking in C++ | Y |
N3421 | Making Operator Functors greater<> | Y |
N3657 | Adding heterogeneous comparison lookup to associative containers | Y |
N3655 | TransformationTraits Redux | Y |
N3644 | Null Forward Iterators | Partial | Only affects Debug Mode

Table 1.4. C++ Technical Specifications Implementation Status

Paper | Title | Status | Comments
--- | --- | --- | ---
N3662 | C++ Dynamic Arrays | N | Array Extensions TS
N3793 | A proposal to add a utility class to represent optional objects | Y | Library Fundamentals TS
N3804 | Any library proposal | Y | Library Fundamentals TS
N3866 | Invocation type traits, but dropping function_call_operator. | N | Library Fundamentals TS
N3905 | Faster string searching (Boyer-Moore et al.) | Y | Library Fundamentals TS
N3915 | apply() call a function with arguments from a tuple | Y | Library Fundamentals TS
N3916 | Polymorphic memory resources | Partial | Library Fundamentals TS
N3920 | Extending shared_ptr to support arrays | Y | Library Fundamentals TS
N3921 | `string_view`: a non-owning reference to a string | Y | Library Fundamentals TS
N3925 | A sample proposal | Y | Library Fundamentals TS
N3932 | Variable Templates For Type Traits | Y | Library Fundamentals TS
N4100 | File System | Y | Link with `-lstdc++fs`

### C++ 2017

In this implementation the `-std=gnu++17` or `-std=c++17` flag must be used to enable language and library features. See dialect options. The pre-defined symbol `__cplusplus` is used to check for the presence of the required flag.

This section describes the C++17 and library TS support in mainline GCC SVN, not in any particular release.

The following table lists new library features that have been accepted into the C++17 working draft. The "Proposal" column provides a link to the ISO C++ committee proposal that describes the feature, while the "Status" column indicates the first version of GCC that contains an implementation of this feature (if it has been implemented). The "SD-6 Feature Test" column shows the corresponding macro or header from SD-6: Feature-testing recommendations for C++.

Table 1.5. C++ 2017 Implementation Status

Library Feature | Proposal | Status | SD-6 Feature Test
--- | --- | --- | ---
`constexpr std::hardware_{constructive,destructive}_interference_size` | P0154R1 | No | `__cpp_lib_hardware_interference_size >= 201603`
Core Issue 1776: Replacement of class objects containing reference members | P0137R1 | 7.1 | `__cpp_lib_launder >= 201606`
Wording for `std::uncaught_exceptions` | N4259 | 6.1 | `__cpp_lib_uncaught_exceptions >= 201411`
Variant: a type-safe union for C++17 | P0088R3 | 7.1 | `__has_include(<variant>)`, `__cpp_lib_variant >= 201603` (since 7.3, see Note 1)
Library Fundamentals V1 TS Components: `optional` | P0220R1 | 7.1 | `__has_include(<optional>)`, `__cpp_lib_optional >= 201603` (since 7.3, see Note 1)
Library Fundamentals V1 TS Components: `any` | P0220R1 | 7.1 | `__has_include(<any>)`, `__cpp_lib_any >= 201603` (since 7.3, see Note 1)
Library Fundamentals V1 TS Components: `string_view` | P0220R1 | 7.1 | `__has_include(<string_view>)`, `__cpp_lib_string_view >= 201603` (since 7.3, see Note 1)
Library Fundamentals V1 TS Components: `memory_resource` | P0220R1 | No | `__has_include(<memory_resource>)`, `__cpp_lib_memory_resource >= 201603`
Library Fundamentals V1 TS Components: `apply` | P0220R1 | 7.1 | `__cpp_lib_apply >= 201603`
Library Fundamentals V1 TS Components: `shared_ptr<T[]>` | P0220R1 | 7.1 | `__cpp_lib_shared_ptr_arrays >= 201603`
Library Fundamentals V1 TS Components: Searchers | P0220R1 | 7.1 | `__cpp_lib_boyer_moore_searcher >= 201603`
Library Fundamentals V1 TS Components: Sampling | P0220R1 | 7.1 | `__cpp_lib_sample >= 201603`
Constant View: A proposal for a `std::as_const` helper function template | P0007R1 | 7.1 | `__cpp_lib_as_const >= 201510`
Improving pair and tuple | N4387 | 6.1 | N/A
`make_from_tuple`: apply for construction | P0209R2 | 7.1 | `__cpp_lib_make_from_tuple >= 201606`
Removing `auto_ptr`, `random_shuffle()`, And Old `<functional>` Stuff | N4190 | No (kept for backwards compatibility) |
Deprecating Vestigial Library Parts in C++17 | P0174R2 | No (kept for backwards compatibility) |
Making `std::owner_less` more flexible | P0074R0 | 7.1 | `__cpp_lib_transparent_operators >= 201510`
`std::addressof` should be constexpr | LWG2296 | 7.1 | `__cpp_lib_addressof_constexpr >= 201603`
Safe conversions in `unique_ptr<T[]>` | N4089 | 6 |
LWG 2228: Missing SFINAE rule in unique_ptr templated assignment | N4366 | 6 |
Re-enabling `shared_from_this` | P0033R1 | 7.1 | `__cpp_lib_enable_shared_from_this >= 201603`
A proposal to add `invoke` function template | N4169 | 6.1 | `__cpp_lib_invoke >= 201411`
TriviallyCopyable `reference_wrapper` | N4277 | 5.1 |
Adopt `not_fn` from Library Fundamentals 2 for C++17 | P0005R4 | 7.1 | `__cpp_lib_not_fn >= 201603`
Fixes for `not_fn` | P0358R1 | 7.1 |
Fixing a design mistake in the searchers interface in Library Fundamentals | P0253R1 | 7.1 |
Extending memory management tools | P0040R3 | 7.1 | ``
`shared_ptr::weak_type` | P0163R0 | 7.1 | `__cpp_lib_shared_ptr_weak_type >= 201606`
Transformation Trait Alias `void_t` | N3911 | 6.1 | `__cpp_lib_void_t >= 201411`
Wording for `bool_constant`, revision 1 | N4389 | 6.1 | `__cpp_lib_bool_constant >= 201505`
Adopt Type Traits Variable Templates from Library Fundamentals TS for C++17 | P0006R0 | 7.1 | `__cpp_lib_type_trait_variable_templates >= 201510`
Logical Operator Type Traits | P0013R1 | 6.1 | `__cpp_lib_logical_traits >= 201510`
Adding [nothrow-]swappable traits | P0185R1 | 7 (`__is_swappable` available since 6.1) | `__cpp_lib_is_swappable >= 201603`
`is_callable`, the missing INVOKE related trait | P0077R2 | 7.1 | `__cpp_lib_is_callable >= 201603`
has_unique_object_representations | P0258R2 | 7.1 | `__cpp_lib_has_unique_object_representations >= 201606`
Polishing `<chrono>` | P0092R1 | 7.1 | `__cpp_lib_chrono >= 201510`
Adding more constexpr to `<chrono>` | P0505R0 | 7.1 | `__cpp_lib_chrono >= 201611` (since 7.3, see Note 2)
Constexpr for `std::char_traits` | P0426R1 | 8 | `__cpp_lib_constexpr_char_traits >= 201611`
Integrating `std::string_view` and `std::string` | P0254R2 | 7.1 | ``
Give 'std::string' a non-const '.data()' member function | P0272R1 | 7.1 | ``
Cleaning-up noexcept in the Library | N4258 | 6.1 | `__cpp_lib_allocator_traits_is_always_equal >= 201411`
Contiguous Iterators | N4284 | N/A |
Minimal incomplete type support for standard containers | N4510 | 3.0 | `__cpp_lib_incomplete_container_elements >= 201505` (since 6.2, see Note 2)
Emplace return type | P0084R2 | 7.1 |
Improved insertion interface for unique-key maps | N4279 | 6.1 | `__cpp_lib_map_try_emplace >= 201411`, `__cpp_lib_unordered_map_try_emplace >= 201411`
Splicing Maps and Sets | P0083R3 | 7.1 | `__cpp_lib_node_extract >= 201606`
Non-member `size()` and more | N4280 | 6.1 | `__cpp_lib_nonmember_container_access >= 201411`
A Proposal to Add Constexpr Modifiers to `reverse_iterator`, `move_iterator`, `array` and Range Access | P0031R0 | 7.1 | `__cpp_lib_array_constexpr >= 201603`
The Parallelism TS Should be Standardized | P0024R2 | No | `__has_include(<execution>)` , `__cpp_lib_execution >= 201603` , `__cpp_lib_parallel_algorithm >= 201603`
An algorithm to "clamp" a value between a pair of boundary values | P0025R0 | 7.1 | `__cpp_lib_clamp >= 201603`
Adopt Selected Library Fundamentals V2 Components for C++17 | P0295R0 | 7.1 | `__cpp_lib_gcd_lcm >= 201606`
Proposal to Introduce a 3-Argument Overload to `std::hypot` | P0030R1 | 7.1 | `__cpp_lib_hypot >= 201603`
Mathematical Special Functions for C++17 | P0226R1 | 7.1 | `__cpp_lib_math_special_functions >= 201603` (see Note 3)
Adopt the File System TS for C++17 | P0218R1 | 8 | `__has_include(<filesystem>)` , `__cpp_lib_filesystem >= 201603` (requires linking with `-lstdc++fs`)
Relative Paths for Filesystem | P0219R1 | 8 | `__cpp_lib_filesystem >= 201606`
Adapting string_view by filesystem paths | P0392R0 | 8 | `__cpp_lib_filesystem >= 201606`
Directory Entry Caching for Filesystem | P0317R1 | 8 | `__cpp_lib_filesystem >= 201703`
constexpr `atomic<T>::is_always_lock_free` | P0152R1 | 7.1 | `__cpp_lib_atomic_is_always_lock_free >= 201603`
A proposal to add `shared_mutex` (untimed) (Revision 4) | N4508 | 6.1 | `__cpp_lib_shared_mutex >= 201505`
Variadic `lock_guard` (Rev. 5) | P0156R2 | 7.1 | `__cpp_lib_scoped_lock >= 201703`
A byte type definition | P0298R3 | 7.1 | `__cpp_lib_byte >= 201603` (since 7.3, see Note 2)
Elementary string conversions | P0067R5 | 8 (only integral types supported) | `__has_include(<charconv>)` `__cpp_lib_to_chars >= 201611`

Note 1: This feature is supported in GCC 7.1 and 7.2 but before GCC 7.3 the `__cpp_lib` macro is not defined, and compilation will fail if the header is included without using `-std` to enable C++17 support.

Note 2: This feature is supported in older releases but the `__cpp_lib` macro is not defined to the right value (or not defined at all) until the version shown in parentheses.

Note 3: The mathematical special functions are enabled in C++17 mode from GCC 7.1 onwards. For GCC 6.x or for C++11/C++14 define `__STDCPP_WANT_MATH_SPEC_FUNCS__` to a non-zero value and test for `__STDCPP_MATH_SPEC_FUNCS__ >= 201003L`.

Table 1.6. C++ Technical Specifications Implementation Status

Paper | Title | Status | Comments
--- | --- | --- | ---
N4076 | A generalized callable negator | Y | Library Fundamentals 2 TS
N4273 | Uniform Container Erasure | Y | Library Fundamentals 2 TS
N4061 | Greatest Common Divisor and Least Common Multiple | Y | Library Fundamentals 2 TS
N4066 | Delimited iterators | Y | Library Fundamentals 2 TS
N4282 | The World's Dumbest Smart Pointer | Y | Library Fundamentals 2 TS
N4388 | Const-Propagating Wrapper | Y | Library Fundamentals 2 TS
N4391 | `make_array`, revision 4 | Y | Library Fundamentals 2 TS
N4502 | Support for the C++ Detection Idiom, V2 | Y | Library Fundamentals 2 TS
N4519 | Source-Code Information Capture | Y | Library Fundamentals 2 TS
N4521 | Merge Fundamentals V1 into V2 | N | Library Fundamentals 2 TS
P0013R1 | Logical Operator Type Traits (revision 1) | Y | Library Fundamentals 2 TS

#### Implementation Specific Behavior

For behaviour which is also specified by previous standards, see C++ 1998/2003 Implementation Specific Behavior and C++ 2011 Implementation Specific Behavior. This section only documents behaviour which is new in the 2017 standard.

23.6.5 [optional.bad_optional_access] `what()` returns `"bad optional access"`.

23.7.3 [variant.variant] Whether `variant` supports over-aligned types should be documented here.

23.7.10 [variant.bad.access] `what()` returns `"Unexpected index"`.

23.12.5.2 [memory.resource.pool.options] The limits for maximum number of blocks and largest allocation size supported by `pool_options` should be documented here.

23.12.6.1 [memory.resource.monotonic.buffer.ctor] The default `next_buffer_size` and growth factor should be documented here.

23.15.4.3 [meta.unary.prop] The predicate condition for `has_unique_object_representations` is true for all scalar types except floating point types.

23.19.3 [execpol.type], 28.4.3 [algorithms.parallel.exec] There are no implementation-defined execution policies.

24.4.2 [string.view.template] `basic_string_view<C, T>::iterator` is `C*` and `basic_string_view<C, T>::const_iterator` is `const C*`.

28.4.3 [algorithms.parallel.exec] Threads of execution created by `std::thread` provide concurrent forward progress guarantees, so threads of execution implicitly created by the library will provide parallel forward progress guarantees.

29.4.1 [cfenv.syn] The effects of the `<cfenv>` functions depends on whether the `FENV_ACCESS` pragma is supported, and on the C library that provides the header.

29.6.9 [c.math.rand] Whether the `rand` function may introduce data races depends on the target C library that provides the function.

29.9.5 [sf.cmath] The effect of calling the mathematical special functions with large inputs should be documented here.

30.10.2.1 [fs.conform.9945] The behavior of the filesystem library implementation will depend on the target operating system. Some features will not be not supported on some targets.

30.10.5 [fs.filesystem.syn] The clock used for file times is `std::chrono::system_clock`.

30.10.7.1 [fs.path.generic] dot-dot in the root-directory refers to the root-directory itself.

### C++ TR1

This table is based on the table of contents of ISO/IEC DTR 19768 Doc No: N1836=05-0096 Date: 2005-06-24 Draft Technical Report on C++ Library Extensions

In this implementation the header names are prefixed by `tr1/`, for instance `<tr1/functional>`, `<tr1/memory>`, and so on.

This page describes the TR1 support in mainline GCC SVN, not in any particular release.

Table 1.7. C++ TR1 Implementation Status

Section | Description | Status | Comments
--- | --- | --- | ---
2 | General Utilities
2.1 | Reference wrappers |  |
2.1.1 | Additions to header `<functional>` synopsis | Y |
2.1.2 | Class template `reference_wrapper` |  |
2.1.2.1 | `reference_wrapper` construct/copy/destroy | Y |
2.1.2.2 | `reference_wrapper` assignment | Y |
2.1.2.3 | `reference_wrapper` access | Y |
2.1.2.4 | `reference_wrapper` invocation | Y |
2.1.2.5 | `reference_wrapper` helper functions | Y |
2.2 | Smart pointers |  |
2.2.1 | Additions to header `<memory>` synopsis | Y |
2.2.2 | Class `bad_weak_ptr` | Y |
2.2.3 | Class template `shared_ptr` |  | Uses code from boost::shared_ptr.
2.2.3.1 | `shared_ptr` constructors | Y |
2.2.3.2 | `shared_ptr` destructor | Y |
2.2.3.3 | `shared_ptr` assignment | Y |
2.2.3.4 | `shared_ptr` modifiers | Y |
2.2.3.5 | `shared_ptr` observers | Y |
2.2.3.6 | `shared_ptr` comparison | Y |
2.2.3.7 | `shared_ptr` I/O | Y |
2.2.3.8 | `shared_ptr` specialized algorithms | Y |
2.2.3.9 | `shared_ptr` casts | Y |
2.2.3.10 | `get_deleter` | Y |
2.2.4 | Class template `weak_ptr` |  |
2.2.4.1 | `weak_ptr` constructors | Y |
2.2.4.2 | `weak_ptr` destructor | Y |
2.2.4.3 | `weak_ptr` assignment | Y |
2.2.4.4 | `weak_ptr` modifiers | Y |
2.2.4.5 | `weak_ptr` observers | Y |
2.2.4.6 | `weak_ptr` comparison | Y |
2.2.4.7 | `weak_ptr` specialized algorithms | Y |
2.2.5 | Class template `enable_shared_from_this` | Y |
3 | Function Objects
3.1 | Definitions | Y |
3.2 | Additions to `<functional> synopsis` | Y |
3.3 | Requirements | Y |
3.4 | Function return types | Y |
3.5 | Function template `mem_fn` | Y |
3.6 | Function object binders |  |
3.6.1 | Class template `is_bind_expression` | Y |
3.6.2 | Class template `is_placeholder` | Y |
3.6.3 | Function template `bind` | Y |
3.6.4 | Placeholders | Y |
3.7 | Polymorphic function wrappers |  |
3.7.1 | Class `bad_function_call` | Y |
3.7.1.1 | `bad_function_call` constructor | Y |
3.7.2 | Class template `function` |  |
3.7.2.1 | `function` construct/copy/destroy | Y |
3.7.2.2 | `function` modifiers | Y |
3.7.2.3 | `function` capacity | Y |
3.7.2.4 | `function` invocation | Y |
3.7.2.5 | `function` target access | Y |
3.7.2.6 | undefined operators | Y |
3.7.2.7 | null pointer comparison operators | Y |
3.7.2.8 | specialized algorithms | Y |
4 | Metaprogramming and type traits
4.1 | Requirements | Y |
4.2 | Header `<type_traits>` synopsis | Y |
4.3 | Helper classes | Y |
4.4 | General Requirements | Y |
4.5 | Unary Type Traits |  |
4.5.1 | Primary Type Categories | Y |
4.5.2 | Composite type traits | Y |
4.5.3 | Type properties | Y |
4.6 | Relationships between types | Y |
4.7 | Transformations between types |  |
4.7.1 | Const-volatile modifications | Y |
4.7.2 | Reference modifications | Y |
4.7.3 | Array modifications | Y |
4.7.4 | Pointer modifications | Y |
4.8 | Other transformations | Y |
4.9 | Implementation requirements | Y |
5 | Numerical Facilities
5.1 | Random number generation |  |
5.1.1 | Requirements | Y |
5.1.2 | Header `<random>` synopsis | Y |
5.1.3 | Class template `variate_generator` | Y |
5.1.4 | Random number engine class templates | Y |
5.1.4.1 | Class template `linear_congruential` | Y |
5.1.4.2 | Class template `mersenne_twister` | Y |
5.1.4.3 | Class template `subtract_with_carry` | Y |
5.1.4.4 | Class template `subtract_with_carry_01` | Y |
5.1.4.5 | Class template `discard_block` | Y |
5.1.4.6 | Class template `xor_combine` | Y | operator()() per N2079
5.1.5 | Engines with predefined parameters | Y |
5.1.6 | Class `random_device` | Y |
5.1.7 | Random distribution class templates | Y |
5.1.7.1 | Class template `uniform_int` | Y |
5.1.7.2 | Class `bernoulli_distribution` | Y |
5.1.7.3 | Class template `geometric_distribution` | Y |
5.1.7.4 | Class template `poisson_distribution` | Y |
5.1.7.5 | Class template `binomial_distribution` | Y |
5.1.7.6 | Class template `uniform_real` | Y |
5.1.7.7 | Class template `exponential_distribution` | Y |
5.1.7.8 | Class template `normal_distribution` | Y |
5.1.7.9 | Class template `gamma_distribution` | Y |
5.2 | Mathematical special functions | Y |
5.2.1 | Additions to header `<cmath>` synopsis | Y |
5.2.1.1 | associated Laguerre polynomials | Y |
5.2.1.2 | associated Legendre functions | Y |
5.2.1.3 | beta function | Y |
5.2.1.4 | (complete) elliptic integral of the first kind | Y |
5.2.1.5 | (complete) elliptic integral of the second kind | Y |
5.2.1.6 | (complete) elliptic integral of the third kind | Y |
5.2.1.7 | confluent hypergeometric functions | Y |
5.2.1.8 | regular modified cylindrical Bessel functions | Y |
5.2.1.9 | cylindrical Bessel functions (of the first kind) | Y |
5.2.1.10 | irregular modified cylindrical Bessel functions | Y |
5.2.1.11 | cylindrical Neumann functions | Y |
5.2.1.12 | (incomplete) elliptic integral of the first kind | Y |
5.2.1.13 | (incomplete) elliptic integral of the second kind | Y |
5.2.1.14 | (incomplete) elliptic integral of the third kind | Y |
5.2.1.15 | exponential integral | Y |
5.2.1.16 | Hermite polynomials | Y |
5.2.1.17 | hypergeometric functions | Y |
5.2.1.18 | Laguerre polynomials | Y |
5.2.1.19 | Legendre polynomials | Y |
5.2.1.20 | Riemann zeta function | Y |
5.2.1.21 | spherical Bessel functions (of the first kind) | Y |
5.2.1.22 | spherical associated Legendre functions | Y |
5.2.1.23 | spherical Neumann functions | Y |
5.2.2 | Additions to header `<math.h>` synopsis | Y |
6 | Containers
6.1 | Tuple types | Y |
6.1.1 | Header `<tuple>` synopsis | Y |
6.1.2 | Additions to header `<utility>` synopsis | Y |
6.1.3 | Class template `tuple` | Y |
6.1.3.1 | Construction | Y |
6.1.3.2 | Tuple creation functions | Y |
6.1.3.3 | Tuple helper classes | Y |
6.1.3.4 | Element access | Y |
6.1.3.5 | Relational operators | Y |
6.1.4 | Pairs | Y |
6.2 | Fixed size array | Y |
6.2.1 | Header `<array>` synopsis | Y |
6.2.2 | Class template `array` | Y |
6.2.2.1 | `array` constructors, copy, and assignment | Y |
6.2.2.2 | `array` specialized algorithms | Y |
6.2.2.3 | `array` size | Y |
6.2.2.4 | Zero sized `array`s | Y |
6.2.2.5 | Tuple interface to class template `array` | Y |
6.3 | Unordered associative containers | Y |
6.3.1 | Unordered associative container requirements | Y |
6.3.1.1 | Exception safety guarantees | Y |
6.3.2 | Additions to header `<functional>` synopsis | Y |
6.3.3 | Class template `hash` | Y |
6.3.4 | Unordered associative container classes | Y |
6.3.4.1 | Header `<unordered_set>` synopsis | Y |
6.3.4.2 | Header `<unordered_map>` synopsis | Y |
6.3.4.3 | Class template `unordered_set` | Y |
6.3.4.3.1 | `unordered_set` constructors | Y |
6.3.4.3.2 | `unordered_set` swap | Y |
6.3.4.4 | Class template `unordered_map` | Y |
6.3.4.4.1 | `unordered_map` constructors | Y |
6.3.4.4.2 | `unordered_map` element access | Y |
6.3.4.4.3 | `unordered_map` swap | Y |
6.3.4.5 | Class template `unordered_multiset` | Y |
6.3.4.5.1 | `unordered_multiset` constructors | Y |
6.3.4.5.2 | `unordered_multiset` swap | Y |
6.3.4.6 | Class template `unordered_multimap` | Y |
6.3.4.6.1 | `unordered_multimap` constructors | Y |
6.3.4.6.2 | `unordered_multimap` swap | Y |
7 | Regular Expressions
7.1 | Definitions | N |
7.2 | Requirements | N |
7.3 | Regular expressions summary | N |
7.4 | Header `<regex>` synopsis | N |
7.5 | Namespace `tr1::regex_constants` | N |
7.5.1 | Bitmask Type `syntax_option_type` | N |
7.5.2 | Bitmask Type `regex_constants::match_flag_type` | N |
7.5.3 | Implementation defined `error_type` | N |
7.6 | Class `regex_error` | N |
7.7 | Class template `regex_traits` | N |
7.8 | Class template `basic_regex` | N |
7.8.1 | `basic_regex` constants | N |
7.8.2 | `basic_regex` constructors | N |
7.8.3 | `basic_regex` assign | N |
7.8.4 | `basic_regex` constant operations | N |
7.8.5 | `basic_regex` locale | N |
7.8.6 | `basic_regex` swap | N |
7.8.7 | `basic_regex` non-member functions | N |
7.8.7.1 | `basic_regex` non-member swap | N |
7.9 | Class template `sub_match` | N |
7.9.1 | `sub_match` members | N |
7.9.2 | `sub_match` non-member operators | N |
7.10 | Class template `match_results` | N |
7.10.1 | `match_results` constructors | N |
7.10.2 | `match_results` size | N |
7.10.3 | `match_results` element access | N |
7.10.4 | `match_results` formatting | N |
7.10.5 | `match_results` allocator | N |
7.10.6 | `match_results` swap | N |
7.11 | Regular expression algorithms | N |
7.11.1 | exceptions | N |
7.11.2 | `regex_match` | N |
7.11.3 | `regex_search` | N |
7.11.4 | `regex_replace` | N |
7.12 | Regular expression Iterators | N |
7.12.1 | Class template `regex_iterator` | N |
7.12.1.1 | `regex_iterator` constructors | N |
7.12.1.2 | `regex_iterator` comparisons | N |
7.12.1.3 | `regex_iterator` dereference | N |
7.12.1.4 | `regex_iterator` increment | N |
7.12.2 | Class template `regex_token_iterator` | N |
7.12.2.1 | `regex_token_iterator` constructors | N |
7.12.2.2 | `regex_token_iterator` comparisons | N |
7.12.2.3 | `regex_token_iterator` dereference | N |
7.12.2.4 | `regex_token_iterator` increment | N |
7.13 | Modified ECMAScript regular expression grammar | N |
8 | C Compatibility
8.1 | Additions to header `<complex>` | Y |
8.1.1 | Synopsis | Y |
8.1.2 | Function `acos` | Y |
8.1.3 | Function `asin` | Y |
8.1.4 | Function `atan` | Y |
8.1.5 | Function `acosh` | Y |
8.1.6 | Function `asinh` | Y |
8.1.7 | Function `atanh` | Y |
8.1.8 | Function `fabs` | Y |
8.1.9 | Additional Overloads | Y |
8.2 | Header `<ccomplex>` | N | DR 551
8.3 | Header `<complex.h>` | N | DR 551
8.4 | Additions to header `<cctype>` | Y |
8.4.1 | Synopsis | Y |
8.4.2 | Function `isblank` | Y |
8.5 | Additions to header `<ctype.h>` | Y |
8.6 | Header `<cfenv>` | Y |
8.6.1 | Synopsis | Y |
8.6.2 | Definitions | Y |
8.7 | Header `<fenv.h>` | Y |
8.8 | Additions to header `<cfloat>` | Y |
8.9 | Additions to header `<float.h>` | Y |
8.10 | Additions to header `<ios>` | N |
8.10.1 | Synopsis | N |
8.10.2 | Function `hexfloat` | N |
8.11 | Header `<cinttypes>` | Y |
8.11.1 | Synopsis | Y | DR 557
8.11.2 | Definitions | Y |
8.12 | Header `<inttypes.h>` | Y |
8.13 | Additions to header `<climits>` | Y |
8.14 | Additions to header `<limits.h>` | Y |
8.15 | Additions to header `<locale>` | N |
8.16 | Additions to header `<cmath>` | Y |
8.16.1 | Synopsis | Y |
8.16.2 | Definitions | Y |
8.16.3 | Function template definitions | Y |
8.16.4 | Additional overloads | Y | DR 568; DR 550
8.17 | Additions to header `<math.h>` | Y |
8.18 | Additions to header `<cstdarg>` | Y |
8.19 | Additions to header `<stdarg.h>` | Y |
8.20 | The header `<cstdbool>` | Y |
8.21 | The header `<stdbool.h>` | Y |
8.22 | The header `<cstdint>` | Y |
8.22.1 | Synopsis | Y |
8.22.2 | Definitions | Y |
8.23 | The header `<stdint.h>` | Y |
8.24 | Additions to header `<cstdio>` | Y |
8.24.1 | Synopsis | Y |
8.24.2 | Definitions | Y |
8.24.3 | Additional format specifiers | Y | C library dependency
8.24.4 | Additions to header `<stdio.h>` | Y |
8.25 | Additions to header `<cstdlib>` | Y |
8.25.1 | Synopsis | Y |
8.25.2 | Definitions | Y |
8.25.3 | Function `abs` | Y |
8.25.4 | Function `div` | Y |
8.26 | Additions to header `<stdlib.h>` | Y |
8.27 | Header `<ctgmath>` | Y | DR 551
8.28 | Header `<tgmath.h>` | Y | DR 551
8.29 | Additions to header `<ctime>` | Y | C library dependency
8.30 | Additions to header `<cwchar>` | Y |
8.30.1 | Synopsis | Y |
8.30.2 | Definitions | Y |
8.30.3 | Additional wide format specifiers | Y | C library dependency
8.31 | Additions to header `<wchar.h>` | Y |
8.32 | Additions to header `<cwctype>` | Y |
8.32.1 | Synopsis | Y |
8.32.2 | Function `iswblank` | Y |
8.33 | Additions to header `<wctype.h>` | Y |

#### Implementation Specific Behavior

For behaviour which is specified by the 1998 and 2003 standards, see C++ 1998/2003 Implementation Specific Behavior. This section documents behaviour which is required by TR1.

3.6.4 [tr.func.bind.place]/1 There are 29 placeholders defined and the placeholder types are `Assignable`.

### C++ TR 24733

This table is based on the table of contents of ISO/IEC TR 24733 Date: 2009-08-28 Extension for the programming language C++ to support decimal floating-point arithmetic

This page describes the TR 24733 support in mainline GCC SVN, not in any particular release.

Table 1.8. C++ TR 24733 Implementation Status

Section | Description | Status | Comments
--- | --- | --- | ---
0 | Introduction
1 | Normative references
2 | Conventions
3 | Decimal floating-point types
3.1 | Characteristics of decimal floating-point types |  |
3.2 | Decimal Types |  |
3.2.1 | Class `decimal` synopsis | Partial | Missing declarations for formatted input/output; non-conforming extension for functions converting to integral type
3.2.2 | Class `decimal32` | Partial | Missing 3.2.2.5 conversion to integral type; conforming extension for conversion from scalar decimal floating-point
3.2.3 | Class `decimal64` | Partial | Missing 3.2.3.5 conversion to integral type; conforming extension for conversion from scalar decimal floating-point
3.2.4 | Class `decimal128` | Partial | Missing 3.2.4.5 conversion to integral type; conforming extension for conversion from scalar decimal floating-point
3.2.5 | Initialization from coefficient and exponent | Y |
3.2.6 | Conversion to generic floating-point type | Y |
3.2.7 | Unary arithmetic operators | Y |
3.2.8 | Binary arithmetic operators | Y |
3.2.9 | Comparison operators | Y |
3.2.10 | Formatted input | N |
3.2.11 | Formatted output | N |
3.3 | Additions to header `limits` | N |
3.4 | Headers `cfloat` and `float.h` |  |
3.4.2 | Additions to header `cfloat` synopsis | Y |
3.4.3 | Additions to header `float.h` synopsis | N |
3.4.4 | Maximum finite value | Y |
3.4.5 | Epsilon | Y |
3.4.6 | Minimum positive normal value | Y |
3.4.7 | Minimum positive subnormal value | Y |
3.4.8 | Evaluation format | Y |
3.5 | Additions to `cfenv` and `fenv.h` | Outside the scope of GCC |
3.6 | Additions to `cmath` and `math.h` | Outside the scope of GCC |
3.7 | Additions to `cstdio` and `stdio.h` | Outside the scope of GCC |
3.8 | Additions to `cstdlib` and `stdlib.h` | Outside the scope of GCC |
3.9 | Additions to `cwchar` and `wchar.h` | Outside the scope of GCC |
3.10 | Facets | N |
3.11 | Type traits | N |
3.12 | Hash functions | N |
4 | Notes on C compatibility

### C++ IS 29124

This table is based on the table of contents of ISO/IEC FDIS 29124 Doc No: N3060 Date: 2010-03-06 Extensions to the C++ Library to support mathematical special functions

Complete support for IS 29124 is in GCC 6.1 and later releases, when using at least C++11 (for older releases or C++98/C++03 use TR1 instead). For C++11 and C++14 the additions to the library are not declared by their respective headers unless `__STDCPP_WANT_MATH_SPEC_FUNCS__` is defined as a macro that expands to a non-zero integer constant. For C++17 the special functions are always declared (since GCC 7.1).

When the special functions are declared the macro `__STDCPP_MATH_SPEC_FUNCS__` is defined to `201003L`.

In addition to the special functions defined in IS 29124, for non-strict modes (i.e. `-std=gnu++NN` modes) the hypergeometric functions and confluent hypergeometric functions from TR1 are also provided, defined in namespace `__gnu_cxx`.

Table 1.9. C++ Special Functions Implementation Status

Section | Description | Status | Comments
--- | --- | --- | ---
7 | Macro names | Partial | No diagnostic for inconsistent definitions of `__STDCPP_WANT_MATH_SPEC_FUNCS__`
8 | Mathematical special functions | Y |
8.1 | Additions to header `<cmath>` synopsis | Y |
8.1.1 | associated Laguerre polynomials | Y |
8.1.2 | associated Legendre functions | Y |
8.1.3 | beta function | Y |
8.1.4 | (complete) elliptic integral of the first kind | Y |
8.1.5 | (complete) elliptic integral of the second kind | Y |
8.1.6 | (complete) elliptic integral of the third kind | Y |
8.1.7 | regular modified cylindrical Bessel functions | Y |
8.1.8 | cylindrical Bessel functions (of the first kind) | Y |
8.1.9 | irregular modified cylindrical Bessel functions | Y |
8.1.10 | cylindrical Neumann functions | Y |
8.1.11 | (incomplete) elliptic integral of the first kind | Y |
8.1.12 | (incomplete) elliptic integral of the second kind | Y |
8.1.13 | (incomplete) elliptic integral of the third kind | Y |
8.1.14 | exponential integral | Y |
8.1.15 | Hermite polynomials | Y |
8.1.16 | Laguerre polynomials | Y |
8.1.17 | Legendre polynomials | Y |
8.1.18 | Riemann zeta function | Y |
8.1.19 | spherical Bessel functions (of the first kind) | Y |
8.1.20 | spherical associated Legendre functions | Y |
8.1.21 | spherical Neumann functions | Y |
8.2 | Additions to header `<math.h>` | Y |
8.3 | The header `<ctgmath>` | Partial | Conflicts with C++ 2011 requirements.
8.4 | The header `<tgmath.h>` | N | Conflicts with C++ 2011 requirements.

#### Implementation Specific Behavior

For behaviour which is specified by the 2011 standard, see C++ 2011 Implementation Specific Behavior. This section documents behaviour which is required by IS 29124.

7.2 [macro.user]/3 /4 The functions declared in Clause 8 are only declared when `__STDCPP_WANT_MATH_SPEC_FUNCS__ == 1` (or in C++17 mode, for GCC 7.1 and later).

8.1.1 [sf.cmath.Lnm]/1 The effect of calling these functions with `n >= 128` or `m >= 128` should be described here.

8.1.2 [sf.cmath.Plm]/3 The effect of calling these functions with `l >= 128` should be described here.

8.1.3 [sf.cmath.I]/3 The effect of calling these functions with `nu >= 128` should be described here.

8.1.8 [sf.cmath.J]/3 The effect of calling these functions with `nu >= 128` should be described here.

8.1.9 [sf.cmath.K]/3 The effect of calling these functions with `nu >= 128` should be described here.

8.1.10 [sf.cmath.N]/3 The effect of calling these functions with `nu >= 128` should be described here.

8.1.15 [sf.cmath.Hn]/3 The effect of calling these functions with `n >= 128` should be described here.

8.1.16 [sf.cmath.Ln]/3 The effect of calling these functions with `n >= 128` should be described here.

8.1.17 [sf.cmath.Pl]/3 The effect of calling these functions with `l >= 128` should be described here.

8.1.19 [sf.cmath.j]/3 The effect of calling these functions with `n >= 128` should be described here.

8.1.20 [sf.cmath.Ylm]/3 The effect of calling these functions with `l >= 128` should be described here.

8.1.21 [sf.cmath.n]/3 The effect of calling these functions with `n >= 128` should be described here.

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