C++ language support

Apple supports C++ with the Apple Clang compiler (included in Xcode) and the libc++ C++ standard library runtime (included in SDKs and operating systems). The compiler and runtime are regularly updated to offer new functionality, including many leading-edge features specified by the ISO C++ standard.

Supported features

The following tables list support for ISO C++ standard features available on Apple platforms and in the Apple Clang compiler, as well as links to related documentation. While most features are supported by all Apple operating systems, some features depend on specific OS capabilities or require support in the libc++.dylib shared library provided with the OS. Code that uses those features should be guarded by the minimal deployment target check as noted.

C++26 (expected)

Feature Paper Notes
Unevaluated strings P2361R6 Requires Xcode 16.3
constexpr cast from void* P2738R1 Requires Xcode 16.3
On the ignorability of standard attributes P2552R3 Requires Xcode 16.3
User-generated static_assert messages P2741R3 Requires Xcode 16.3
Placeholder variables with no name P2169R4 Requires Xcode 16.3
Template parameter initialization P2308R1 Requires Xcode 16.3
Remove Deprecated Arithmetic Conversion on Enumerations P2864R2 Requires Xcode 16.3
Clarifying rules for brace elision in aggregate initialization P3106R1 Requires Xcode 16.3
Pack Indexing P2662R3 Requires Xcode 16.3
\= delete("should have a reason"); P2573R2 Requires Xcode 16.3
Attributes for Structured Bindings P0609R3 Requires Xcode 16.3
Disallow Binding a Returned Glvalue to a Temporary P2748R5 Requires Xcode 16.3
Trivial infinite loops are not Undefined Behavior P2809R3 Requires Xcode 16.3
Deleting a Pointer to an Incomplete Type Should be Ill-formed P3144R2 Requires Xcode 16.3
Ordering of constraints involving fold expressions P2963R3 Requires Xcode 16.3
Remove undefined behavior from lexing P2621R2 (DR) Requires Xcode 16
Making non-encodable string literals ill-formed P1854R4 (DR) Requires Xcode 16
Add @, ,ドル and ` to the basic character set P2558R2 Requires Xcode 15 or later
Unevaluated strings P2361R6 Requires Xcode 16
Features implemented in the libc++ library
constexpr placement new P2747R2 Requires Xcode 26
A type trait for detecting virtual base classes P2985R0 Requires Xcode 26
Concatenation of strings and string_views P2591R5 Requires Xcode 16.3
Member visit P2637R3 Requires Xcode 16.3
Printing Blank Lines with println P3142R0 Requires Xcode 16.3
Interfacing stringstreams with string_view P2495R3 Requires Xcode 16.3
Add tuple protocol to complex P2819R2 Requires Xcode 16.3
Testing for success or failure of <charconv> functions P2497R0 Requires Xcode 16
ADL-proof std::projected P2538R1 Requires Xcode 16
Native handles and file streams P1759R6 Requires Xcode 16
Interfacing bitset with string_view P2697R1 Requires Xcode 16
Saturation arithmetic P0543R3 Requires Xcode 16
Runtime format strings P2905R2 Requires Xcode 16
Runtime format strings II P2918R2 Requires Xcode 16
Fix formatting of code units as integers (Dude, where’s my char?) P2909R4 Requires Xcode 16
std::span over an initializer list P2447R6 Requires Xcode 16
span.at() P2821R5 Requires Xcode 16
Remove Deprecated std::allocator Typedef From C++26 P2868R3 Requires Xcode 16
Remove basic_string::reserve() From C++26 P2870R3 Requires Xcode 16
Remove Deprecated Unicode Conversion Facets from C++26 P2871R3 Requires Xcode 16

C++23

Feature Paper Notes
Deducing this P0847R7 Requires Xcode 16.3
Change scope of lambda trailing-return-type P2036R3 Requires Xcode 16.3
Relaxing some constexpr restrictions P2448R2 Requires Xcode 16.3
A type trait to detect reference binding to temporary P2255R2 Requires Xcode 16.3
Static and explicit object member functions with the same parameter-type-lists P2797R0 Requires Xcode 16.3
The Equality Operator You Are Looking For P2468R2 Requires Xcode 16
Labels at the end of compound statements P2324R2 Requires Xcode 16
static operator() P1169R4 Requires Xcode 16
char8_t Compatibility and Portability Fix P2513R3 Requires Xcode 16
static operator[] P2589R1 Requires Xcode 16
Permitting static constexpr variables in constexpr functions P2647R1 Requires Xcode 16
consteval needs to propagate up P2564R3(DR) Requires Xcode 16
Referencing The Unicode Standard P2736R2 Requires Xcode 16
De-deprecating volatile compound operations. P2327R1 Requires Xcode 15 or later
Support for #warning P2437R1 Requires Xcode 15 or later
Remove non-encodable wide character literals and multicharacter wide character literals P2362R3 Requires Xcode 15 or later
Delimited escape sequences P2290R3 Requires Xcode 15 or later
Named universal character escapes P2071R2 Requires Xcode 15 or later
Support for UTF-8 as a portable source file encoding P2295R6 Requires Xcode 15 or later
Relax requirements on wchar_t to match existing practices P2460R2 Requires Xcode 15 or later
Multidimensional subscript operator P2128R6 Requires Xcode 14.3 or later
Non-literal variables (and labels and gotos) in constexpr functions P2242R3 Requires Xcode 14.3 or later
auto(x): decay-copy in the language P0849R8 Requires Xcode 14.3 or later
Literal suffix uz, z for size_t, ssize_t P0330R8
Make () in lambdas optional in all cases P1102R2
if consteval P1938R3
Allow duplicate attributes P2156R1
Narrowing contextual conversions to bool P1401R5
Trimming whitespaces before line splicing P2223R2
C++ identifier syntax using unicode standard annex 31 P1949R7
Mixed string literal concatenation P2201R1
Character sets and encodings P2314R4
Consistent character literal encoding P2316R2
Preprocessing directives elifdef and elifndef P2334R1
Extend init-statement to allow alias-declaration P2360R0
Attributes on lambda expressions P2173R1
Make declaration order layout mandated P1847R4
Features implemented in the libc++ library
Relaxing Ranges Just A Smidge P2609R3 Requires Xcode 26
A trait for implicit lifetime types P2674R1 Requires Xcode 26
A Standard flat_map P0429R9 Requires Xcode 26
Pipe support for user-defined range adaptors P2387R3 Requires Xcode 16.3
out_ptr - a scalable output pointer abstraction P1132R8 Requires Xcode 16.3
std::ranges::contains_subrange (std::ranges::contains has been implemented in a previous release) P2302R4 Requires Xcode 16.3
ranges::find_last(), ranges::find_last_if(), and anges::find_last_if_not() P1223R5 Requires Xcode 16.3
Poison Pills are Too Toxic P2602R2 Requires Xcode 16.3
starts_with and ends_with P1659R3 Requires Xcode 16
views::chunk_by P2443R1 Requires Xcode 16
std::ranges::contains P2302R4

Requires Xcode 16

Not supported: std::ranges::contains_subrange
Support exclusive mode for fstreams P2467R1 Requires Xcode 16
Add a conditional noexcept specification to std::apply P2517R1 Requires Xcode 16
Should the output of std::print to a terminal be synchronized with the underlying stream? P2539R4 Requires Xcode 16
Deprecate numeric_limits::has_denorm P2614R2 Requires Xcode 16
Formatting ranges P2286R8 Requires Xcode 15.3 or later
ranges::to : A function to convert any range to a container P1206R7 Requires Xcode 15.3 or later
move_iterator<T*> should be a random access iterator P2520R0 Requires Xcode 15.3 or later
constexpr type_info::operator==() P1328R1 Requires Xcode 15.3 or later
Formatting thread::id P2693R1 Requires Xcode 15.3 or later
Monadic operations for std::expected P2505R5 Requires Xcode 15.3 or later
Making multi-param constructors of views explicit P2711R1 Requires Xcode 15.3 or later
std::invoke_r P2136R3 Requires Xcode 15.3 or later
Relaxing range adaptors to allow for move only types P2494R2 Requires Xcode 15.3 or later
Improving default container formatting P2585R1 Requires Xcode 15.3 or later
std::ranges::views::repeat P2474R2 Requires Xcode 15.3 or later
std::mdspan P0009R18 Requires Xcode 15.3 or later
Formatted output P2093R14 Requires Xcode 15.3 or later
Add the missing empty to mdspan P2613R1 Requires Xcode 15.3 or later
mdspan: rename pointer and contiguous P2604R0 Requires Xcode 15.3 or later
string_view range constructor should be explicit P2499R0 Requires Xcode 15 or later
A more constexpr bitset P2417R2 Requires Xcode 15 or later
forward_like P2445R1 Requires Xcode 15 or later
Making std::unique_ptr constexpr P2273R3 Requires Xcode 15 or later
Add constexpr modifiers to functions to_chars and from_chars for integral types in <charconv> header P2291R3 Requires Xcode 15 or later
std::string::substr() && P2438R2 Requires Xcode 15 or later
std::expected P0323R12 Requires Xcode 15 or later
views::as_rvalue P2446R2 Requires Xcode 15 or later
std::unexpected should have error() as member accessor P2549R1 Requires Xcode 15 or later
Conditionally borrowed ranges P2017R1 Requires Xcode 15 or later
Function to mark unreachable code std::unreachable() P0627R6 Requires Xcode 14.3 or later
Type trait to detect scoped enumerations std::is_scoped_enum P1048R1
contains() function for basic_string and basic_string_view P1679R3
std::to_underlying for enumerations P1682R3
std::visit() for classes derived from std::variant P2162R2
Prevent overconstraining allocators in container deduction guides P1518R2
Prohibit basic_string and basic_string_view construction from nullptr P2166R1
Require span & basic_string_view to be trivially copyable P2251R1

C++20

Feature Paper Notes
Class types as non-type template parameters P0732R2 Requires Xcode 16.3
Immediate functions (consteval) P1073R3 Requires Xcode 16.3
typename optional in more contexts P0634R3 Requires Xcode 16
Structured binding extensions P1091R3 Requires Xcode 16
P1381R1
Parenthesized initialization of aggregates P0960R3 Requires Xcode 16
P1975R0
Concepts P0734R0 Not supported: papers P2103R0, DR1496, DR1734, P0848R3
P1084R2
P1141R2
P1616R1
P1452R2
P1972R0
P1980R0
P2493R0
P2092R0
Immediate functions (consteval) P1073R3 Requires Xcode 15 or later
P1937R2
Default member initializers for bit-fields P0683R1
Fix const-qualified (const&-qualified) pointers to members P0704R1
Allow lambda-capture [=, this] P0409R2
__VA_OPT__ for comma omission and comma deletion P0306R4
P1042R1
Designated initializers P0329R4
Familiar template-parameter-list syntax for generic lambdas P0428R2
Range-based for statements with initializer P0614R1
ADL and function templates that are not visible P0846R0
const mismatch with defaulted copy constructor P0641R2
Consistent comparison (operator<=>) P0515R3
P0905R1
P1120R0
P1185R2
P1186R3
P1630R1
P1946R0
P1959R0
P2085R0
Relaxing access checking on specializations P0692R1
Default constructible and assignable stateless lambdas P0624R2
Allowing lambdas in unevaluated contexts P0315R4 Not supported: [temp.deduct/9]
[[no_unique_address]] attribute P0840R2
[[likely]] and [[unlikely]] attributes P0479R5
Pack expansion in lambda init-capture P0780R2
Relaxations of constexpr restrictions P1064R0
P1002R1
P1327R1
P1330R0
P1331R2
P1668R1
P0784R7
Prohibit aggregates with user-declared constructors P1008R1
Feature test macros P0941R2
explicit(bool): conditionally explicit constructor P0892R2
Signed integers are two’s complement P1236R1
char8_t: A type for UTF-8 characters and strings P0482R6
std::is_constant_evaluated P0595R2
Nested inline namespaces P1094R2
Stronger unicode requirements P1041R4
P1139R2
Coroutines P0912R5
Deprecate comma operator in subscripting expressions like a[b,c] P1161R3
Deprecate some problematic uses of volatile P1152R4
[[nodiscard("with reason")]] P1301R4
using enum P1099R5
Permit conversions to arrays of unknown bound P0388R4
constinit P1143R2
Pseudo-destructors end object lifetimes P0593R6 (DR)
Implicit move for more local objects and rvalue references P1825R0 (DR)
Features implemented in the libc++library
Reviewing Deprecated Facilities of C++17 for C++20 P0619R4 Requires Xcode 26
The Mothership has Landed: Adding <=> to the Library P1614R2 Requires Xcode 16.3
Symmetry for spaceship P0905R1 Requires Xcode 16.3
std::atomic_ref P0019R8 Requires Xcode 16.3
Add wait/notify to atomic_ref<T> P1643R1 Requires Xcode 16.3
Missing constexpr in std::optional and std::variant P2231R1 Requires Xcode 16.3
Floating Point Atomic P0020R6 Requires Xcode 16
Text formatting (std::format) P0645R10 Requires Xcode 15.3 or later
Efficient access to basic_stringbuf’s buffer P0408R7 Requires Xcode 15.3 or later
Utility functions to implement uses-allocator construction P0591R4 Requires Xcode 15 or later
char8_t: A type for UTF-8 characters and strings P0482R6 Requires Xcode 15 or later
nodiscard in the Library P0600R1 Requires Xcode 15 or later
polymorphic_allocator<> as a vocabulary type P0339R6 Requires Xcode 15 or later
Constexpr for std::complex P0415R1 Requires Xcode 15 or later
Adopt source_location for C++20 P1208R6 Requires Xcode 15 or later
Input Range Adaptors P1035R7 Requires Xcode 15 or later
Views should not be required to be default constructible P2325R3 Requires Xcode 15 or later
Smart pointer creation with default initialization P1020R1 Requires Xcode 15 or later
Superior String Splitting P2210R2 Requires Xcode 15 or later
basic_istream_view::iterator should not be copyable P1638R1 Requires Xcode 15 or later
Output std::chrono::days with ‘d’ suffix P1650R0 Requires Xcode 15 or later
Ranges adaptors for non-copyable iterators P1862R1 Requires Xcode 15 or later
Rename "_default_init" Functions, Rev1 P1973R1 Requires Xcode 15 or later
elements_view needs its own sentinel P1994R1 Requires Xcode 15 or later
Fix istream_view P2432R1 Requires Xcode 15 or later
Making std::vector constexpr P1004R2 Requires Xcode 14.3 or later
Consistent stateful allocator propagation for operator+(basic_string) P1165R1 Requires Xcode 14.3 or later
Support arrays in make_shared and allocate_shared P0674R1 Requires Xcode 14.3 or later
Making std::string constexpr P0980R1 Requires Xcode 14.3 or later
Consider ATOMIC_FLAG_INIT undeprecation LWG3659 Requires Xcode 14.3 or later
char8_t backward compatibility remediation P1423R3 Requires Xcode 14.3 or later
Bit-casting object representations P0476R2 Requires Xcode 14.3 or later
Ranges P0896R4 Requires Xcode 14.3 or later
P2415R2 Requires Xcode 14.3 or later
P2281R1 Requires Xcode 14.3 or later
std::endian P0463R1
Add constexpr modifiers to functions in <algorithm> and <utility> headers P0202R3
Make std::memory_order a scoped enumeration P0439R0
String prefix and suffix checking P0457R2
Transformation trait remove_cvref P0550R2
De-pessimize legacy <numeric> algorithms with std::move P0616R0
Utility to convert a pointer to a raw pointer P0653R2
Deprecate is_pod P0767R1
Library support for the spaceship (comparison) operator <=> P0768R1
Treating unnecessary decay P0777R1
<span> P0122R7
Thou shalt not specialize std function templates! P0551R3
<version> P0754R2
Comparing unordered containers P0809R0
Constexpr iterator requirements P0858R0
string::reserve should not shrink P0966R1
Checking for existence of an element in associative containers P0458R2
Guaranteed copy elision for piecewise construction P0475R1
Integral power-of-2 operations P0556R3
Reviewing deprecated facilities of C++17 for C++20 P0619R4 Not supported: P0619, Sections D.4, D.7, D.11, and D.12
Improving the return value of erase-like algorithms P0646R1
Efficient sized delete for variable sized classes P0722R3
Implicit conversion traits and utility functions P0758R1
fpos requirements P0759R1
Add shift to <algorithm> P0769R2
constexpr for swap and swap related functions P0879R0
The identity metafunction P0887R1
Standard library concepts P0898R3
Eradicating unnecessarily explicit default constructors P0935R0
constexpr comparison operators for std::array P1023R0
std::unwrap_ref_decay and std::unwrap_reference P0318R1
Simplified partial function application P0356R5
Supporting Incomplete types In reference_wrapper P0357R3
Fixing operator>>(basic_istream&, CharT*) P0487R1
std::is_constant_evaluated() P0595R2
Variant and optional should propagate copy/move triviality P0602R4
Improving variant’s Converting Constructor/Assignment P0608R3
visit<R>: explicit return type for visit P0655R1
std::function move constructor should be noexcept P0771R1
Heterogeneous lookup for unordered containers P0919R3
<chrono> zero(), min(), and max() should be noexcept P0972R0
constexpr in std::pointer_traits P1006R1
Misc constexpr bits P1032R1
Remove comparison operators of std::span P1085R2
Adopt consistent container erasure from library fundamentals 2 P1209R0
Remove CommonReference requirement from StrictWeakOrdering P1248R1
Making std::underlying_type SFINAE-friendly P0340R3
Well-behaved interpolation for numbers and pointers P0811R3
Usability enhancements for std::span P1024R3
Make create_directory() intuitive P1164R1
signed ssize() functions, unsigned size() functions P1227R2
Traits for [Un]bounded Arrays P1357R1
Mandating the standard library: Clause 16 - Language support library P1458R1
Mandating the standard library Clause 18 - Diagnostics library P1459R1
Mandating the standard library: Clause 20 - Strings library P1462R1
Mandating the standard library: Clause 22 - Iterators library P1464R1
to_array from LFTS with updates P0325R4
Bit operations P0553R4
Math constants P0631R8
More onstexpr containers P0784R7
constexpr invoke P1065R2
Synchronization library (<barrier>, <latch>, <semaphore> and notification functions on std::atomic) P1135R6 Minimum deployment target:
macOS 11.0, iOS 14.0, tvOS 14.0, watchOS 7.0
Exposing a narrow contract for ceil2 P1355R2
Relocate endian’s specification P1612R1
bind_front should not unwrap reference_wrapper P1651R0
Remove dedicated precalculated hash lookup interface P1661R1
Fixing atomic initialization P0883R2
Range constructor for std::string_view P1391R4
Range constructor for std::span P1394R4
constexpr for numeric algorithms P1645R1
Heterogeneous lookup for unordered containers P1690R1
Add max() to latch and barrier P1865R1 Minimum deployment target:
macOS 11.0, iOS 14.0, tvOS 14.0, watchOS 7.0
Concept traits should be named after concepts P1871R1
span should have size_type, not index_type P1872R0
Remove std::weak_equality and std::strong_equality P1959R0
Safe integral comparisons P0586R2
Improving the return value of erase-like algorithms II: free erase/erase if P1115R3
On the names of low-level bit manipulation functions P1956R1
Wording for boolean-testable P1964R2
Fixed-size span construction from dynamic range P1976R2
Remove tuple-like protocol support from fixed-extent span P2116R0
Missing constexpr in std::optional and std::variant P2231R1 Not supported: changes to std::variant

C++17

Feature Paper Notes
static_assert with no message N3928
Removing trigraphs N4086
typename in a template template parameter N4051
New auto rules for direct-list-initialization N3922
Fold expressions N4295
P0036R0
u8 character literals P0036R0
Nested namespace definition N4230
Attributes for namespaces and enumerators N4266
Allow constant evaluation for all non-type template arguments N4268
Remove deprecated register storage class P0001R1
Remove deprecated bool increment P0002R1
Make exception specifications part of the type system P0012R1
__has_include in preprocessor conditionals P0061R1
[[fallthrough]] attribute P0188R1
[[nodiscard]] attribute P0189R1
P1771R1 (DR)
[[maybe_unused]] attribute P0212R1
Aggregate initialization of classes with base classes P0017R1
constexpr lambda expressions P0170R1
Differing begin and end types in range-based for P0184R0
Lambda capture of *this P0018R3
Direct-list-initialization of enums P0138R2
Hexadecimal floating-point literals P0245R1
Using attribute namespaces without repetition P0028R4
Dynamic memory allocation for over-aligned data P0035R4
Template argument deduction for class templates P0091R3
P0512R0
P0620R0 (DR)
P0702R1 (DR)
Non-type template parameters with auto type P0127R2
Guaranteed copy elision P0135R1
Stricter expression evaluation order P0145R3
P0400R0
Requirement to ignore unknown attributes P0283R2
constexpr if statements P0292R2
Inline variables P0386R2
Structured bindings P0217R3
P0961R1 (DR)
P0969R0 (DR)
Separate variable and condition for if and switch P0305R1
Matching of template template-parameters to arguments P0522R0 This feature can be source breaking. Should be enabled explicitly with the compiler flag -frelaxed-template-template-args
Removing deprecated dynamic exception specifications P0003R5
Features implemented in the libc++library
<memory_resource> P0220R1

Requires Xcode 15

Minimum deployment target: iOS 17.0, macOS 14.0, watchOS 10.0 and tvOS 17.0.
Filesystem library P0219R1 Minimum deployment target:
macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0
P0218R1
P0392R0
P0317R1
P0492R2
TransformationTrait Alias void_t. N3911
Invoke function template N4169
std::uncaught_exceptions N4259
TriviallyCopyable reference_wrapper. N4277
Improved insertion interface for unique-key maps. N4279
std::size(), std::empty() and std::data() N4280
Contiguous Iterators N4284
Cleanup for exception-specification and throw-expression. N4285
Improving std::pair and std::tuple N4387
bool_constant N4389
shared_mutex N4508

Pass -fno-exceptions compiler flag to back deploy to older OSes. Note that methods that throw exceptions on failure will abort in this mode.
LWG 2228 missing SFINAE rule N4366
Minimal incomplete type support for standard containers N4510
Remove deprecated iostreams aliases. P0004R1
Adopt type traits variable templates for C++17 P0006R0
Polishing <chrono> P0092R1
Constant view: std::as_const helper function template. P0007R1
Making std::owner_less more flexible P0074R0
Logical type traits rev 2 P0013R1
Re-enabling shared_from_this P0033R1
Adopt not_fn from library fundamentals 2 for C++17 P0005R4
constexpr atomic::is_always_lock_free P0152R1
[nothrow-]swappable traits P0185R1
Fixing a design mistake in the searchers interface P0253R1
An algorithm to clamp a value between a pair of boundary values P0025R0
3-argument overload to std::hypot P0030R1
Constexpr modifiers for reverse_iterator, move_iterator, array and Range Access P0031R0
Give std::string a non-const .data() member function P0272R1
is_callable, the missing INVOKE related trait P0077R2
Homogeneous interface for variant, any and optional P0032R3
Extending memory management tools P0040R3
C++17 should refer to C11 instead of C99 P0063R3
Splicing maps and sets P0083R3
Emplace return type P0084R2
Variant: a type-safe union for C++17 P0088R3

Minimum deployment target:
bad_variant_access and methods that throw it: get and visit require macOS 10.13, iOS 11.0, tvOS 11.0, watchOS 4.0

Pass -fno-exceptions compiler flag to back deploy to older OSes. Note that methods that throw exceptions on failure will abort in this mode.
Replacement of class objects containing reference members P0137R1
shared_ptr::weak_type P0163R0
Synopses for the c library P0175R1
Reserve a new library namespace for future standardization P0180R2
make_from_tuple: apply for construction P0209R2
Integrating std::string_view and std::string P0254R2
has_unique_object_representations P0258R2
Adopt selected library fundamentals V2 components for C++17 P0295R0
Adopt library fundamentals V1 TS components for C++17 (optional, string_view, any) P0220R1

Minimum deployment target:
bad_optional_access and bad_any_cast, and methods that throw them: optional::value and any_cast require macOS 10.13, iOS 12.0, tvOS 12.0, watchOS 5.0

Pass -fno-exceptions compiler flag to back deploy to older OSes. Note that methods that throw exceptions on failure will abort in this mode.
Removing allocator support in std::function P0302R1
Making optional greater equal again P0307R2
Better names for parallel execution policies in C++17 P0336R1
Delete operator= for polymorphic_allocator P0337R0
A <random> nomenclature tweak P0346R1
Fixes for not_fn P0358R1
Temporarily discourage memory_order_consume P0371R1
Making variant greater equal P0393R3
Removing deprecated exception specifications from C++17 P0003R5
Elementary string conversions std::to_chars, std::from_chars P0067R5

Minimum deployment target:
For integral types, macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0

For floating-point types, macOS 13.3, iOS 16.3, tvOS 16.3, watchOS 9.3
Literal suffixes for basic_string_view P0403R1
Merging shared_ptr changes from Library Fundamentals to C++17 P0414R2
Constexpr for std::char_traits P0426R1
Resolving LWG Issues re common_type P0435R1
Correcting library usage of "literal type" P0503R0
Revisiting in-place tag types for any/optional/variant P0504R0
Wording for GB 50 - constexpr for chrono P0505R0
Updating "Restrictions on exception handling" P0509R1
Disallowing references, incomplete types, arrays, and empty variants P0510R0
Poisoning the hash P0513R0
Clarify that shared_future’s copy operations have wide contracts P0516R0
Make future_error constructible P0517R0
shared_ptr use_count/unique P0521R0
Variadic lock guard(rev 5) P0156R2
A byte type definition P0298R3
File system library on non-POSIX-like operating systems P0430R2
Integrating template deduction for class templates into the standard library P0433R2
common_type and duration P0548R1
Resolving atomic<T> named base class inconsistencies P0558R1
noexcept for hash functions P0599R1
Resolving GB 55, US 84, US 85, US 86 P0604R0
Some improvements to class template argument deduction integration into the standard library P0739R0

C++14

Feature Paper Notes
Tweak to certain c++ contextual conversions N3323
Binary literals N3472
decltype(auto) N3638
Return type deduction for normal functions
Initialized lambda captures N3648
Generic lambdas N3649
Variable templates N3651
Relaxing requirements on constexpr functions N3652
Member initializers and aggregates N3653
Clarifying memory allocation N3664
[[deprecated]] attribute N3760
Single quotation mark as digit separator N3781
Sized deallocation (delete and delete[]) N3778
Features implemented in the libc++library
Terminology for container element requirements - Rev 1 N3346
Making operator functors greater<> N3421
std::result_of and SFINAE N3462
integral_constant improvements N3545
Null forward iterators N3644
std::exchange() N3668
Compile-time integer sequences N3658
Addressing tuples by type N3670
Making non-modifying sequence operations more robust N3671
make_unique N3656
Quoted Strings N3654
User-defined Literals N3642
TransformationTraits Redux (excluding part 4) N3655
Heterogeneous comparison lookup N3657
Fixing constexpr member functions without const N3669
Shared locking N3659
User-defined literals for std::complex N3779
Discouraging rand() N3924
Consistent metafunction aliases N3887
Rename shared_mutex to shared_timed_mutex N3891
Constexpr library additions: chrono, containers, utilities, complex numbers, functional N3469
N3470
N3471
N3302
N3789

C++11

Feature Paper Notes
Rvalue references N2118
P1825R0 (DR)
Rvalue references for *this N2439
Initialization of class objects by rvalues N1610
Non-static data member initializers N2756
Variadic templates N2242
Extending variadic template template parameters N2555
Initializer lists N2672
P1009R2 (DR)
P1957R2 (DR)
Static assertions N1720
auto-typed variables N1984
Multi-declarator auto N1737
Removal of auto as a storage-class specifier N2546
New function declarator syntax N2541
Declared type of an expression N2343
Incomplete return types N3276
Right angle brackets N1757
Default template arguments for function templates DR226
Solving the SFINAE problem for expressions DR339
Alias templates N2258
Extern templates N1987
Null pointer constant N2431
Strongly-typed enums N2347
Forward declarations for enums N2764
DR1206
Standardized attribute syntax N2761
ConstExpr: generalized constant expressions N2235
P0859R0 (DR)
Alignment support N2341
Conditionally-support behavior N1627
Changing undefined behavior into diagnosable errors N1727
Delegating constructors N1986
Inheriting constructors N2540
P0136R1 (DR)
Explicit conversion operators N2437
New character types N2249
Unicode string literals N2442
Raw string literals N2442
Universal character names in literals N2170
User-defined literals N2765
Standard Layout Types N2342
Defaulted functions N2346
P1286R2 (DR)
Deleted functions N2346
Extended friend declarations N1791
Extending sizeof N2253
DR850
Inline namespaces N2535
Unrestricted unions N2544
Local and unnamed types as template arguments N2657
Range-based for N2930
P0962R1 (DR)
Explicit virtual overrides N2928
N3206
N3272
Allowing move constructors to throw [noexcept] N3050
Defining move special member functions N3053
Concurrency
Sequence points N2239
Atomic operations N2427
Strong compare and exchange N2748
Bidirectional fences N2752
Memory model N2429
Data-dependency ordering: atomics and memory model N2664
Propagating exceptions N2179
Allow atomics use in signal handlers N2547
Thread-local storage N2659
Dynamic initialization and destruction with concurrency N2660
C99 Features in C++11
__func__ predefined identifier N2340
C99 preprocessor N1653
long long N1811

C++98/03

Clang and libc++ supports all features of the ISO C++ 1998 standard and the defects addressed in the ISO C++ 2003 standard.

C++ standard library hardening

Starting in Xcode 16, the C++ standard library supports hardening. Turning on hardening enables checks for common cases of misuse of the standard library; if a check fails, the program is reliably terminated, helping prevent security vulnerabilities and diagnose some cases of undefined behavior.

Hardening can be turned on via Xcode Build Settings (Apple Clang - Language - C++ > Enable C++ Standard Library Hardening):

  • "No" — don’t enable any hardening checks.
  • "Yes (fast)" — enable low-overhead security-critical checks at runtime. We recommend most applications to adopt this setting in the production environment.
  • "Yes (extensive)" — enable all available low-overhead checks at runtime, including general logic errors in addition to security vulnerabilities. This setting has a higher overhead compared to "Yes" but is still intended to be usable in production by applications that would benefit from the increased level of correctness checking.
  • "Yes (debug)" — enable all available checks, including heuristic checks that might have significant performance overhead, as well as internal library assertions. We recommend most applications to use this setting in non-production environments (such as test suites and CI, as well as for local development). This setting should not be used in production due to the overhead.

Note that the Debug configuration enables debug hardening mode by default. When enabling hardening, make sure not to accidentally override the stricter debug mode with a less-strict production-capable mode in the Debug configuration. Turning on hardening might expose latent bugs and cause the application to terminate at runtime. We recommend testing your code thoroughly in a development environment.

For more information about hardening, refer to the libc++ documentation.