C++17

This section is incomplete

The following features were merged into C++17:

• From the File System TS : the filesystem library .
• From the Library fundamentals v1 TS : features, including std::any , std::optional , std::string_view , std::apply , polymorphic allocators , searchers .
• From Library fundamentals v2 TS : std::void_t , std::conjunction , std::disjunction , std::negation , std::not_fn , std::gcd , std::lcm .
• From Parallelism v1 TS : features, including execution policies , std::reduce , std::inclusive_scan , std::exclusive_scan , but removing exception_list .
• From Mathematical special functions IS : mathematical special functions .
• From C11: std::aligned_alloc , std::timespec_get .

Obsolete

Removed:

• std::auto_ptr ,
• deprecated function objects ,
• std::random_shuffle ,
• std::unexpected ,
• the obsolete iostream s aliases ,
• trigraphs ,
• the register keyword,
• bool increment ,
• dynamic exception specification

Deprecated:

• std::iterator ,
• std::raw_storage_iterator ,
• std::get_temporary_buffer ,
• std::is_literal_type ,
• std::result_of ,
• all of <codecvt>

New language features

• u8 character literal
• made noexcept part of type system
• new order of evaluation rules
• lambda capture of * this

• constexpr

  compile-time if constexpr

  constexpr lambda

• Variables

  inline variables

  structured bindings

  initializers for if and switch

  guaranteed copy elision

  temporary materialization

• Templates

  fold-expressions ( ... )

  class template argument deduction tuple t ( 4 , 3 , 2.5 )

  non-type template parameters declared with auto

• Namespaces

  simplified nested namespaces

  using -declaration declaring multiple names

  attribute namespaces don't have to repeat

• new attributes :
  • [[ fallthrough ]]
  • [[ maybe_unused ]]
  • [[ nodiscard ]]
• __has_include

New headers

• <any>
• <charconv>
• <execution>
• <filesystem>
• <memory_resource>
• <optional>
• <string_view>
• <variant>

New library features

Utility types

• std::tuple :
  • std::apply
  • std::make_from_tuple
  • deduction guides
• std::any
• std::optional
• std::variant
• searchers
• std::as_const
• std::not_fn

Memory management

• uninitialized memory algorithms
  • std::destroy_at
  • std::destroy
  • std::destroy_n
  • std::uninitialized_move
  • std::uninitialized_value_construct
• weak_from_this
• std::pmr::memory_resource and std::polymorphic_allocator
• std::aligned_alloc
• transparent std::owner_less
• array support for std::shared_ptr
• allocation functions with explicit alignment

Compile-time programming

• std::byte
• std::conjunction / std::disjunction / std::negation
• type trait variable templates ( xxx _+v )
• std::is_swappable
• std::is_invocable
• std::is_aggregate
• std::has_unique_object_representations

Algorithms

• std::clamp
• parallel algorithms and execution policies
• std::inclusive_scan
• std::exclusive_scan
• std::gcd
• std::lcm
• std::reduce

Iterators and containers

• map/set extract and map/set merge
• map/unordered_map try_emplace and insert_or_assign
• contiguous iterators ( LegacyContiguousIterator )
• non-member std::size / std::empty / std::data

Numerics

• mathematical special functions
• 3D std::hypot

Others

• cache line interface
• std::launder
• std::uncaught_exceptions
• std::to_chars / std::from_chars
• std::atomic<T>::is_always_lock_free
• std::scoped_lock
• std::timespec_get
• rounding functions for std::chrono::duration and std::chrono::time_point

Defect reports

Compiler support

C++17 core language features

C++17 feature	Paper(s)	GCC	Clang	MSVC	Apple Clang	EDG eccp	Intel C++	IBM XL C++	IBM Open XL C++ for AIX	IBM Open XL C++ for z/OS	Sun/Oracle C++	Embarcadero C++ Builder	Cray	Nvidia HPC C++ (ex PGI)*	Nvidia nvcc
DR11: New auto rules for direct-list-initialization	N3922	5	3.8	19.0 (2015)*	Yes	4.10.1	17.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
static_assert with no message	N3928	6	2.5	19.10*	Yes	4.12	18.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
typename in a template template parameter	N4051	5	3.5	19.0 (2015)*	Yes	4.10.1	17.0		17.1.0	1.1.0		10.3	11.0	17.7	Yes*
Removing trigraphs	N4086	5	3.5	16.0*	Yes	5.0			17.1.0	1.1.0		10.3	11.0	19.1	11.0
Nested namespace definition	N4230	6	3.6	19.0 (Update 3)*	Yes	4.12	17.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
Attributes for namespaces and enumerators	N4266	4.9 (partial)* 6	3.6	19.0 (2015)*	Yes	4.11	17.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
u8 character literals	N4267	6	3.6	19.0 (2015)*	Yes	4.11	17.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
Allow constant evaluation for all non-type template arguments	N4268	6	3.6	19.12*	Yes	5.0	19.0.1		17.1.0	1.1.0		10.3	11.0	19.1	11.0
Fold Expressions	N4295	6	3.6	19.12*	Yes	4.14	19.0		17.1.0	1.1.0		10.3	11.0	18.1	11.0
Unary fold expressions and empty parameter packs	P0036R0	6	3.9	19.12*	Yes	4.14	19.0		17.1.0	1.1.0		10.3	11.0	19.1	11.0
Remove Deprecated Use of the register Keyword	P0001R1	7	3.8	19.11*	Yes	4.13	18.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
Remove Deprecated operator++(bool)	P0002R1	7	3.8	19.11*	Yes	4.13	18.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
Make exception specifications part of the type system	P0012R1	7	4	19.12*	Yes	4.14	19.0		17.1.0	1.1.0		10.3	11.0	19.1	11.0
Aggregate classes with base classes	P0017R1	7	3.9	19.14*	Yes	5.0	19.0.1		17.1.0	1.1.0		10.3	11.0	19.1	11.0
__has_include in preprocessor conditionals	P0061R1	5	Yes	19.11*	Yes	4.13	18.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
DR11: New specification for inheriting constructors (DR1941 et al)	P0136R1	7	3.9	19.14 (partial)*	Yes	6.1			17.1.0	1.1.0		10.3	11.0	19.1	11.0
Lambda capture of *this	P0018R3	7	3.9	19.11*	Yes	4.14	19.0		17.1.0	1.1.0		10.3	11.0	18.1	11.0
Direct-list-initialization of enumerations	P0138R2	7	3.9	19.11*	Yes	4.14	18.0		17.1.0	1.1.0		10.3	11.0	19.1	11.0
constexpr lambda expressions	P0170R1	7	5	19.11*	Yes	4.14	19.0		17.1.0	1.1.0		10.3	11.0	18.1	11.0
Differing begin and end types in range-based for	P0184R0	6	3.9	19.10*	Yes	4.12	18.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
[[ fallthrough ]] attribute	P0188R1	7	3.9	19.10*	Yes	4.13	18.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
[[ nodiscard ]] attribute	P0189R1	7	3.9	19.11*	Yes	4.13	18.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
[[ maybe_unused ]] attribute	P0212R1	7	3.9	19.11*	Yes	4.13	18.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
Hexadecimal floating-point literals	P0245R1	3.0	Yes	19.11*	Yes	4.13	18.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
Using attribute namespaces without repetition	P0028R4	7	3.9	19.11*	Yes	4.13	18.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
Dynamic memory allocation for over-aligned data	P0035R4	7	4	19.12*	10.0.0*	4.14	19.0		17.1.0	1.1.0		10.3	11.0	19.1	11.0
Class template argument deduction	P0091R3	7	5	19.14*	Yes	5.0	19.0.1		17.1.0	1.1.0		10.3	11.0	19.1	11.0
Non-type template parameters with auto type	P0127R2	7	4	19.14*	Yes	5.0	19.0.1		17.1.0	1.1.0		10.3	11.0	19.1	11.0
Guaranteed copy elision	P0135R1	7	4	19.13*	Yes	5.0	19.0.1		17.1.0	1.1.0		10.3	11.0	19.1	11.0
Replacement of class objects containing reference members	P0137R1	7	6	19.14*	Yes	5.0			17.1.0	1.1.0		10.3	11.0	19.1	11.0
Stricter expression evaluation order	P0145R3	7	4	19.14*	Yes	5.0	19.0.1		17.1.0	1.1.0		10.3	11.0	19.1	11.0
Structured Bindings	P0217R3	7	4	19.11*	Yes	4.14	19.0		17.1.0	1.1.0		10.3	11.0	18.1	11.0*
Ignore unknown attributes	P0283R2	Yes	3.9	19.11*	Yes	4.13	18.0		17.1.0	1.1.0		10.3	11.0	17.7	11.0
constexpr if statements	P0292R2	7	3.9	19.11*	Yes	4.14	19.0		17.1.0	1.1.0		10.3	11.0	18.1	11.0
init-statements for if and switch	P0305R1	7	3.9	19.11*	Yes	4.14	18.0		17.1.0	1.1.0		10.3	11.0	18.1	11.0
Inline variables	P0386R2	7	3.9	19.12*	Yes	4.14	19.0		17.1.0	1.1.0		10.3	11.0	18.1	11.0
Removing dynamic exception specifications	P0003R5	7	4	19.10*	Yes	4.14	19.0		17.1.0	1.1.0		10.3	11.0	19.1	11.0
Pack expansions in using-declarations	P0195R2	7	4	19.14*	Yes	5.0	19.0		17.1.0	1.1.0		10.3	11.0	19.1	11.0
DR98: Matching of template template-arguments excludes compatible templates	P0522R0	7	4	19.12*	Yes	5.0	19.0.1		17.1.0	1.1.0		10.3	11.0	19.1	11.0
C++17 feature	Paper(s)	GCC	Clang	MSVC	Apple Clang	EDG eccp	Intel C++	IBM XL C++	IBM Open XL C++ for AIX	IBM Open XL C++ for z/OS	Sun/Oracle C++	Embarcadero C++ Builder	Cray	Nvidia HPC C++ (ex PGI)*	Nvidia nvcc

C++17 library features

C++17 feature	Paper(s)	GCC libstdc++	Clang libc++	MSVC STL	Apple Clang*	IBM Open XL C/C++ for AIX*	Intel Parallel STL	Sun/Oracle C++*	Embarcadero C++ Builder*
std::void_t	N3911	6	3.6	19.0 (2015)*	Yes	17.1.0	N/A		10.3
std::uncaught_exceptions()	N4259	6	3.7	19.0 (2015)*	Yes	17.1.0	N/A		10.3
std::size() , std::empty() and std::data()	N4280	6	3.6	19.0 (2015)*	Yes	17.1.0	N/A		10.3
Improving std::pair and std::tuple	N4387	6	4	19.0 (Update 2)*	Yes	17.1.0	N/A		10.3
std::bool_constant	N4389	6	3.7	19.0 (2015)*	Yes	17.1.0	N/A		10.3
std::shared_mutex (untimed)	N4508	6	3.7	19.0 (Update 2)*	Yes	17.1.0	N/A		10.3
Type traits variable templates	P0006R0	7	3.8	19.0 (Update 2)*	Yes	17.1.0	N/A		10.3
Logical operator type traits	P0013R1	6	3.8	19.0 (Update 2)*	Yes	17.1.0	N/A		10.3
Parallel algorithms and execution policies	P0024R2	9*	17 (partial)*	19.14*			18.0*
std::clamp()	P0025R1	7	3.9	19.0 (Update 3)*	10.0.0*	17.1.0	N/A		10.3
Hardware interference size	P0154R1	12	15 (partial)* 19	19.11*			N/A		10.3
(nothrow-)swappable traits	P0185R1	7	3.9	19.0 (Update 3)*	10.0.0*	17.1.0	N/A		10.3
File system library ( std::filesystem )	P0218R1	8	7	19.14*	11.0.0*	17.1.1	N/A		10.3
std::string_view	N3921 P0220R1	7	4	19.10*	10.0.0*	17.1.0	N/A		10.3
std::any	P0220R1	7	4	19.10*	10.0.0*	17.1.0	N/A		10.3
std::optional	P0220R1	7	4	19.10*	10.0.0*	17.1.0	N/A		10.3
Polymorphic memory resources	P0220R1	9	16	19.13*	15.0.0*		N/A		10.3
Mathematical special functions	P0226R1	7		19.14*			N/A		10.3
Major portion of C11 standard library	P0063R3	9	7	19.0 (2015)* (partial)*	10.0.0*	17.1.1	N/A
Splicing Maps and Sets	P0083R3	7	8	19.12*	10.0.0*	17.1.1	N/A
return type of emplace * functions of some containers changed from void to reference	P0084R2	7.1	4.0	19.11*	Yes	17.1.0	N/A
std::variant	P0088R3	7	4	19.10*	10.0.0*	17.1.0	N/A		10.3
std::make_from_tuple()	P0209R2	7	3.9	19.10*	Yes	17.1.0	N/A		10.3
std::has_unique_object_representations	P0258R2	7	6	19.11*	Yes	17.1.1	N/A		10.3
std::gcd() and std::lcm()	P0295R0	7	4	19.11*	Yes	17.1.0	N/A		10.3
std::not_fn	P0005R4 P0358R1	7	3.9	19.12*	Yes	17.1.0	N/A		10.3
Elementary string conversions : std:: to_chars / std:: from_chars	P0067R5	8* 11	7* 14* 20*	19.14* * 19.24*	10.0.0* *	17.1.1*	N/A		10.3*
std::shared_ptr and std::weak_ptr with array support	P0414R2	7	11	19.12*	12.0.0*	17.1.1	N/A		10.3
std::scoped_lock	P0156R2	7	5	19.11*	Yes	17.1.1	N/A		10.3
std::byte	P0298R3	7	5	19.11*	Yes	17.1.1	N/A		10.3
std::is_aggregate	LWG2911	7	5	19.15*	Yes	17.1.1	N/A		10.3
DR17: std::hash<std::filesystem::path>	LWG3657	11.4	17	19.32*			N/A
C++17 feature	Paper(s)	GCC libstdc++	Clang libc++	MSVC STL	Apple Clang*	IBM Open XL C/C++ for AIX*	Intel Parallel STL	Sun/Oracle C++*	Embarcadero C++ Builder*

Notes

• As of 2020-11-20, the latest release of Oracle Developer Studio is 12.6 . Its documentation does not mention C++17.
• Cray compiler may have support for some features earlier than 11.0. That version is when it became a derivative of Clang, gaining all of the attendant language feature support of the base compiler. See Cray/HPE document S-2179 .

* - hover over a cell marked with the star * to see additional pop-up notes.
DR nn - the number nn after "DR" denotes target C++ revision the Defect Report is applied to, e.g., DR20 → C++20.

External links

Working C++17 examples